La Estabilización de la capa de Balasto mediante las geomallas TriAx -desarrolladas por Tensar International y distribuidas por EMIN Sistemas Geotecnicos- puede retrasar considerablemente los períodos de mantenimiento entre las operaciones, alargando notablemente la vida útil.
Network Rail's revised Code of Practice now encourages using more innovative techniques like geogrid reinforcement to improve trackbed performance over soft or unstable ground. Stiff polymer grids have been used successfully in the UK for decades to reinforce ballast on difficult sites. Recent research and monitored installations continue to show benefits, including reduced maintenance needs. The first project using the new Code involved placing geogrid under 1.5km of track near Derby known for poor geometry, restrictions, and frequent maintenance due to variable unstable ground. Initial results showed improvements.
This document discusses various methods and standards for measuring pavement surface characteristics like skid resistance and texture. It covers topics like factors that influence skid resistance, methods for measuring micro-texture and macro-texture, standards for measuring polished stone value, and devices for measuring skid resistance at different speeds. The summary provides an overview of the key methods and standards discussed in the document.
This document analyzes stone columns using PLAXIS software. It summarizes:
1) Objectives to analyze the bearing capacity, excess pore pressure mitigation, and drain capacity of single stone columns, stone columns supporting a road embankment, and groups of stone columns with geosynthetics.
2) PLAXIS software is used to model stone columns with various loads, soil properties, and geometries.
3) Results show stone columns reduce settlement, excess pore pressures, and improve drainage compared to untreated soil. Geosynthetics further improve performance of stone column groups.
4) Calculations using Priebe's method show settlement reduction depends on area ratio and stone
This document discusses the design principles, components, and methods for designing both flexible and rigid pavements according to IRC standards, describing the roles of subgrade soil, pavement layers, traffic characteristics, and materials used for flexible pavements consisting of granular bases and bituminous surfaces, as well as jointed concrete slabs for rigid pavements. It also provides an example of designing a two-lane bypass pavement based on initial traffic volume, design life, growth rate, and subgrade CBR value.
Effect of l b ratio of stone column on bearing capacity and relative settleme...IAEME Publication
This study experimentally analyzed the effect of L/B ratio of stone columns on the bearing capacity and settlement of sandy soil. Model tests were conducted with a square footing and single stone column with L/B ratios of 0.5, 1, 2, 2.5, and 3. The results showed that the minimum relative settlement corresponded to an L/B ratio of 2.5, which also had the highest bearing capacity of 318 kN/m2. Increasing the L/B ratio beyond 2.5 did not significantly improve the bearing capacity. Thus, the optimal L/B ratio for a single stone column was determined to be 2.5 based on minimizing settlement and maximizing capacity.
Heavy duty pavements are pavements subjected to the extremely heavy wheel loads associated with freight handling vehicles in industrial facilities, such as container terminals and warehouses. Heavy duty pavement need to handle many types of freight handling vehicles, such as forklifts, straddle carriers, gantry cranes and side loaders. Heavy duty pavement often deals with slow moving or even static traffic load with ultra high load magnitude. Furthermore, the load wandering for heavy duty pavement such as contain port or warehouse is more significant than normal highway or urban road pavement. The goal of pavement design is to determine the number, material composition and thickness of the different layers within a pavement structure required to accommodate a given loading regime.
Ground Improvement by Vibro Stone ColumnsDesh Sonyok
Vibro replacement stone column is one of the widely used soil improvement technique to improve the settlement characteristics, bearing capacity and mitigate the liquefaction issues of the soft soil. In this paper, improvement of the settlement characteristics of the soft soil is considered for the analysis based on the available case histories. A settlement estimation method proposed by Preibe (1995) is verified quantitatively. Finally, an analytical solution for settlement of soft ground for the stone column design is proposed. The proposed method of calculating settlement is based on the basic concept of composite material and soil mechanics. However, the result of this preliminary work is yet to validate numerically and in the field. Detailed research in future is necessary to check its validity and applicability
Network Rail's revised Code of Practice now encourages using more innovative techniques like geogrid reinforcement to improve trackbed performance over soft or unstable ground. Stiff polymer grids have been used successfully in the UK for decades to reinforce ballast on difficult sites. Recent research and monitored installations continue to show benefits, including reduced maintenance needs. The first project using the new Code involved placing geogrid under 1.5km of track near Derby known for poor geometry, restrictions, and frequent maintenance due to variable unstable ground. Initial results showed improvements.
This document discusses various methods and standards for measuring pavement surface characteristics like skid resistance and texture. It covers topics like factors that influence skid resistance, methods for measuring micro-texture and macro-texture, standards for measuring polished stone value, and devices for measuring skid resistance at different speeds. The summary provides an overview of the key methods and standards discussed in the document.
This document analyzes stone columns using PLAXIS software. It summarizes:
1) Objectives to analyze the bearing capacity, excess pore pressure mitigation, and drain capacity of single stone columns, stone columns supporting a road embankment, and groups of stone columns with geosynthetics.
2) PLAXIS software is used to model stone columns with various loads, soil properties, and geometries.
3) Results show stone columns reduce settlement, excess pore pressures, and improve drainage compared to untreated soil. Geosynthetics further improve performance of stone column groups.
4) Calculations using Priebe's method show settlement reduction depends on area ratio and stone
This document discusses the design principles, components, and methods for designing both flexible and rigid pavements according to IRC standards, describing the roles of subgrade soil, pavement layers, traffic characteristics, and materials used for flexible pavements consisting of granular bases and bituminous surfaces, as well as jointed concrete slabs for rigid pavements. It also provides an example of designing a two-lane bypass pavement based on initial traffic volume, design life, growth rate, and subgrade CBR value.
Effect of l b ratio of stone column on bearing capacity and relative settleme...IAEME Publication
This study experimentally analyzed the effect of L/B ratio of stone columns on the bearing capacity and settlement of sandy soil. Model tests were conducted with a square footing and single stone column with L/B ratios of 0.5, 1, 2, 2.5, and 3. The results showed that the minimum relative settlement corresponded to an L/B ratio of 2.5, which also had the highest bearing capacity of 318 kN/m2. Increasing the L/B ratio beyond 2.5 did not significantly improve the bearing capacity. Thus, the optimal L/B ratio for a single stone column was determined to be 2.5 based on minimizing settlement and maximizing capacity.
Heavy duty pavements are pavements subjected to the extremely heavy wheel loads associated with freight handling vehicles in industrial facilities, such as container terminals and warehouses. Heavy duty pavement need to handle many types of freight handling vehicles, such as forklifts, straddle carriers, gantry cranes and side loaders. Heavy duty pavement often deals with slow moving or even static traffic load with ultra high load magnitude. Furthermore, the load wandering for heavy duty pavement such as contain port or warehouse is more significant than normal highway or urban road pavement. The goal of pavement design is to determine the number, material composition and thickness of the different layers within a pavement structure required to accommodate a given loading regime.
Ground Improvement by Vibro Stone ColumnsDesh Sonyok
Vibro replacement stone column is one of the widely used soil improvement technique to improve the settlement characteristics, bearing capacity and mitigate the liquefaction issues of the soft soil. In this paper, improvement of the settlement characteristics of the soft soil is considered for the analysis based on the available case histories. A settlement estimation method proposed by Preibe (1995) is verified quantitatively. Finally, an analytical solution for settlement of soft ground for the stone column design is proposed. The proposed method of calculating settlement is based on the basic concept of composite material and soil mechanics. However, the result of this preliminary work is yet to validate numerically and in the field. Detailed research in future is necessary to check its validity and applicability
This document outlines the content for a course on pavement design called CEE320 at Washington State University. It covers topics such as the purpose and significance of pavements, types of pavement materials and structures, design methods, and an example design problem. The course will discuss flexible and rigid pavements, parameters for pavement design, and use the AASHTO and WSDOT design methods. References for further information are also provided.
topics which are discussed in this slide are,
1) pavement and requirement for pavement design.
2) Rigid and flexible pavement .
3) pavement design method.
This document provides an overview of stone columns, which are columns of compacted aggregate installed in soft soils to improve their load-bearing capacity and reduce settlement. Stone columns function by transferring load to the stiffer column material, allowing drainage of pore water pressures. They are installed using ramming or vibro-replacement techniques. Failure typically occurs through bulging of the column into the surrounding soil. A case study demonstrates that a highway embankment treated with stone columns at 2m spacing experienced 25% less settlement than untreated ground.
This document discusses the design of flexible granular pavements. It outlines the different types of pavement, including flexible pavements made of unbound granular materials and sometimes bituminous or cement stabilized materials. It also discusses rigid pavements made of Portland cement concrete. The document then focuses on analyzing the structural capacity of pavements and the factors considered in design, such as subgrade strength, pavement materials, and design traffic loading over the life of the pavement. Case studies are also presented.
This document provides an overview of the IRC method for designing flexible pavements according to IRC: 37-2012. It discusses the key considerations and calculations involved, including design traffic, subgrade properties like CBR and resilient modulus, material properties, and traffic data collection. The goal is to design a flexible pavement for a new four-lane divided national highway using the IRC guidelines and given traffic and material property data.
This document discusses the design of flexible and rigid pavements. It describes the key components of flexible pavements including the subgrade, subbase, base, and bituminous surface layers. It provides information on evaluating the strength of each layer, particularly the subgrade using CBR testing. The document also outlines the IRC method for designing flexible pavements based on traffic levels and subgrade CBR value using design charts. Rigid pavements are also introduced as being designed based on elastic theory and consisting of cement concrete slabs.
Minor Project on design and analysis of flexible pavement with cement treated...PrashannaKumar2
This document describes the different layers of flexible pavement and analyzes strains at critical locations. It includes:
1) A description of typical flexible pavement layers including surface course, binder course, base layer, sub-base layer, and subgrade.
2) An analysis of strains in flexible pavements with different base layers (granular base and cement treated base) under single wheel, dual wheel, and tandem axle loads using KENPAVE software.
3) The maximum tensile strains at the bottom of the surface course and maximum compressive strains at the top of the subgrade were identified as critical locations for fatigue cracking and rutting, respectively.
This document summarizes a study on the design of flexible pavements. It includes an abstract that outlines a comparison of total present costs between flexible pavement and jointed plain concrete pavement for two case study roads. The document then lists contents that will be covered, including introduction to flexible pavements and their layers/functions, different flexible pavement design approaches, testing and materials used, construction processes, and a conclusion. It provides an overview of flexible pavement requirements, types, load transfer mechanisms, and common flexible pavement constructions.
The 6.1m high retaining wall of a proposed multi-storey building failed during heavy rains from a tropical storm. The wall was designed as a framed structure using incorrect backfill properties and lacked adequate weep holes. Samples of the backfill were tested, revealing it to be clayey sand. When redesigned as a retaining wall based on actual properties, it required more reinforcement. The structural engineer's design provided insufficient strength and stability, leading to the wall's failure before completion of the building framework intended to support it. Retaining walls are best designed and built independently rather than as part of a framed structure.
Combine piled raft foundation (cprf)_Er.Karan ChauhanEr.Karan Chauhan
Combine Piled Raft Foundation(CPRF) is an emerging type of new foundation techniques in High rise buildings and skyscraper which raft as a shallow foundation and pile as deep foundation works sharing the total load and reduce settlement and bending moment. the modern approach of design philosophy is included in post graduation level with soil structure interaction of CPRF and this will use to understand the basic concept regarding it.
This document discusses the deterioration of bituminous roads over time due to factors like traffic loading, climate conditions, and lack of maintenance. It describes different base types, surface treatments, and distresses like cracking, rutting, and roughness that can occur. Models are presented for predicting how conditions like roughness will progress based on factors such as age, strength, and surface distresses. The effects of different maintenance activities are also addressed, as well as frameworks for scheduling routine and responsive interventions.
This document summarizes the evolution of road design from ancient times to modern practices. It describes ancient stone-paved roads from 5000 years ago. It then covers the design of Roman roads, including their layered structures and materials. Road design continued to evolve in the 17th-18th centuries with designers like Tresaguet and Telford introducing compacted stone layers and sloping shoulders. Macadam further refined the use of compacted broken stone. The document outlines the development of modern pavement design methodology and performance models, including concepts like mechanistic-empirical design, Superpave, and perpetual pavements. It concludes by describing various pavement performance tests and equipment.
This document provides details about the design of a highway with flexible pavement for a project presented by 6 students and guided by Prof. Alak Roy. It includes sections on the site location, types of pavement, flexible pavement design, wheel load transfer, super elevation, camber, shoulders, surveying, testing, types of bitumen, drainage system, and carriageway. Test results for CBR, aggregate impact and abrasion values are presented. The flexible pavement design according to IRC-37-2001 for a 30 MSA load and 5% CBR includes a stone soling, granular sub-base, wet mix macadam and bituminous concrete layers with a total thickness of 555mm. The advantages and disadvantages of
Minor Project on design and analysis of flexible pavement with cement treated...PrashannaKumar2
This document is a minor project report submitted in partial fulfillment of a Bachelor of Technology degree in Civil Engineering. It discusses the design and analysis of a flexible pavement with a cement treated base course. The report was prepared by three students and submitted in October 2019 under the guidance of an associate professor. It includes the design of the flexible pavement sections based on IRC37 guidelines and analysis of the pavement layers under different traffic loads.
This document summarizes a study on the effect of geogrids in low volume flexible pavements. The study included constructing 9 pavement sections with different thicknesses and with or without geogrid reinforcement. Instruments were used to measure pavement responses to loading. Results showed sections with geogrid reinforcement had less rutting and lower stresses and strains throughout the pavement structure compared to unreinforced sections. Specifically, geogrid was found to be most effective when placed in thicker base layers and at the base-subgrade interface.
This document provides an introduction to pavement design concepts, including the different types of pavements, principles of pavement design, failure criteria, and pavement thickness design approaches. It discusses flexible and rigid pavements, and how stresses are distributed differently in each. It also covers design life, performance and failure criteria, and the relative damage concept used to quantify traffic loads. Finally, it summarizes the empirical and mechanistic-empirical methods for determining pavement thickness to meet structural and functional requirements over the design life.
This document summarizes a study that analyzed the performance of vertical skirted strip footings on slopes using the finite element software PLAXIS 2D. Various parameters were considered, including the vertical load, depth of footing embedment, distance of footing from crest, ratio of skirt depth to footing width, and configuration of the skirt (one side, both sides, unequal sides). The results showed that skirted foundations significantly improved the bearing capacity compared to unskirted foundations. Bearing capacity increased with deeper skirt depths. Footings at the crest also showed improved bearing capacity. Footing embedment depth did not affect bearing capacity. The study provides insights into using skirted foundations to improve slope stability and bearing capacity
Stone columns are a versatile ground improvement technique used since the 1950s. They involve compacting coarse aggregate in columns in the ground to reinforce, densify and drain weak soils. Stone columns can improve bearing capacity, stability, reduce settlements and mitigate liquefaction. They work by transferring loads around them to stiffer columns, accelerating consolidation. Installation methods include ramming and vibro-replacement. Case studies show stone column embankments experience less settlement than untreated ground. In summary, stone columns are an effective ground improvement technique to strengthen weak soils.
Las Geomallas TriAx® distribuidas por EMIN Sistemas Geotecnicos y desarrolladas por Tensar International han demostrado ser extremadamente eficientes en confinar y estabilizar los agregados. Las Geomallas TriAx son una evolución natural de las geomallas biaxiales en términos de estabilización, ofreciendo incluso un mayor ahorro de coste.
Tensar mechanically stabilized layers can provide high-performance working platforms for surface mining operations by increasing load-bearing capacity over weak subgrades. These layers reduce maintenance costs by limiting rutting and potholes on haul roads. Tensar offers geogrid and geotextile products, as well as design and installation expertise, to stabilize unbound aggregate layers for roads, working areas, railway trackbeds, tailings lagoon caps, and leach pads.
This document outlines the content for a course on pavement design called CEE320 at Washington State University. It covers topics such as the purpose and significance of pavements, types of pavement materials and structures, design methods, and an example design problem. The course will discuss flexible and rigid pavements, parameters for pavement design, and use the AASHTO and WSDOT design methods. References for further information are also provided.
topics which are discussed in this slide are,
1) pavement and requirement for pavement design.
2) Rigid and flexible pavement .
3) pavement design method.
This document provides an overview of stone columns, which are columns of compacted aggregate installed in soft soils to improve their load-bearing capacity and reduce settlement. Stone columns function by transferring load to the stiffer column material, allowing drainage of pore water pressures. They are installed using ramming or vibro-replacement techniques. Failure typically occurs through bulging of the column into the surrounding soil. A case study demonstrates that a highway embankment treated with stone columns at 2m spacing experienced 25% less settlement than untreated ground.
This document discusses the design of flexible granular pavements. It outlines the different types of pavement, including flexible pavements made of unbound granular materials and sometimes bituminous or cement stabilized materials. It also discusses rigid pavements made of Portland cement concrete. The document then focuses on analyzing the structural capacity of pavements and the factors considered in design, such as subgrade strength, pavement materials, and design traffic loading over the life of the pavement. Case studies are also presented.
This document provides an overview of the IRC method for designing flexible pavements according to IRC: 37-2012. It discusses the key considerations and calculations involved, including design traffic, subgrade properties like CBR and resilient modulus, material properties, and traffic data collection. The goal is to design a flexible pavement for a new four-lane divided national highway using the IRC guidelines and given traffic and material property data.
This document discusses the design of flexible and rigid pavements. It describes the key components of flexible pavements including the subgrade, subbase, base, and bituminous surface layers. It provides information on evaluating the strength of each layer, particularly the subgrade using CBR testing. The document also outlines the IRC method for designing flexible pavements based on traffic levels and subgrade CBR value using design charts. Rigid pavements are also introduced as being designed based on elastic theory and consisting of cement concrete slabs.
Minor Project on design and analysis of flexible pavement with cement treated...PrashannaKumar2
This document describes the different layers of flexible pavement and analyzes strains at critical locations. It includes:
1) A description of typical flexible pavement layers including surface course, binder course, base layer, sub-base layer, and subgrade.
2) An analysis of strains in flexible pavements with different base layers (granular base and cement treated base) under single wheel, dual wheel, and tandem axle loads using KENPAVE software.
3) The maximum tensile strains at the bottom of the surface course and maximum compressive strains at the top of the subgrade were identified as critical locations for fatigue cracking and rutting, respectively.
This document summarizes a study on the design of flexible pavements. It includes an abstract that outlines a comparison of total present costs between flexible pavement and jointed plain concrete pavement for two case study roads. The document then lists contents that will be covered, including introduction to flexible pavements and their layers/functions, different flexible pavement design approaches, testing and materials used, construction processes, and a conclusion. It provides an overview of flexible pavement requirements, types, load transfer mechanisms, and common flexible pavement constructions.
The 6.1m high retaining wall of a proposed multi-storey building failed during heavy rains from a tropical storm. The wall was designed as a framed structure using incorrect backfill properties and lacked adequate weep holes. Samples of the backfill were tested, revealing it to be clayey sand. When redesigned as a retaining wall based on actual properties, it required more reinforcement. The structural engineer's design provided insufficient strength and stability, leading to the wall's failure before completion of the building framework intended to support it. Retaining walls are best designed and built independently rather than as part of a framed structure.
Combine piled raft foundation (cprf)_Er.Karan ChauhanEr.Karan Chauhan
Combine Piled Raft Foundation(CPRF) is an emerging type of new foundation techniques in High rise buildings and skyscraper which raft as a shallow foundation and pile as deep foundation works sharing the total load and reduce settlement and bending moment. the modern approach of design philosophy is included in post graduation level with soil structure interaction of CPRF and this will use to understand the basic concept regarding it.
This document discusses the deterioration of bituminous roads over time due to factors like traffic loading, climate conditions, and lack of maintenance. It describes different base types, surface treatments, and distresses like cracking, rutting, and roughness that can occur. Models are presented for predicting how conditions like roughness will progress based on factors such as age, strength, and surface distresses. The effects of different maintenance activities are also addressed, as well as frameworks for scheduling routine and responsive interventions.
This document summarizes the evolution of road design from ancient times to modern practices. It describes ancient stone-paved roads from 5000 years ago. It then covers the design of Roman roads, including their layered structures and materials. Road design continued to evolve in the 17th-18th centuries with designers like Tresaguet and Telford introducing compacted stone layers and sloping shoulders. Macadam further refined the use of compacted broken stone. The document outlines the development of modern pavement design methodology and performance models, including concepts like mechanistic-empirical design, Superpave, and perpetual pavements. It concludes by describing various pavement performance tests and equipment.
This document provides details about the design of a highway with flexible pavement for a project presented by 6 students and guided by Prof. Alak Roy. It includes sections on the site location, types of pavement, flexible pavement design, wheel load transfer, super elevation, camber, shoulders, surveying, testing, types of bitumen, drainage system, and carriageway. Test results for CBR, aggregate impact and abrasion values are presented. The flexible pavement design according to IRC-37-2001 for a 30 MSA load and 5% CBR includes a stone soling, granular sub-base, wet mix macadam and bituminous concrete layers with a total thickness of 555mm. The advantages and disadvantages of
Minor Project on design and analysis of flexible pavement with cement treated...PrashannaKumar2
This document is a minor project report submitted in partial fulfillment of a Bachelor of Technology degree in Civil Engineering. It discusses the design and analysis of a flexible pavement with a cement treated base course. The report was prepared by three students and submitted in October 2019 under the guidance of an associate professor. It includes the design of the flexible pavement sections based on IRC37 guidelines and analysis of the pavement layers under different traffic loads.
This document summarizes a study on the effect of geogrids in low volume flexible pavements. The study included constructing 9 pavement sections with different thicknesses and with or without geogrid reinforcement. Instruments were used to measure pavement responses to loading. Results showed sections with geogrid reinforcement had less rutting and lower stresses and strains throughout the pavement structure compared to unreinforced sections. Specifically, geogrid was found to be most effective when placed in thicker base layers and at the base-subgrade interface.
This document provides an introduction to pavement design concepts, including the different types of pavements, principles of pavement design, failure criteria, and pavement thickness design approaches. It discusses flexible and rigid pavements, and how stresses are distributed differently in each. It also covers design life, performance and failure criteria, and the relative damage concept used to quantify traffic loads. Finally, it summarizes the empirical and mechanistic-empirical methods for determining pavement thickness to meet structural and functional requirements over the design life.
This document summarizes a study that analyzed the performance of vertical skirted strip footings on slopes using the finite element software PLAXIS 2D. Various parameters were considered, including the vertical load, depth of footing embedment, distance of footing from crest, ratio of skirt depth to footing width, and configuration of the skirt (one side, both sides, unequal sides). The results showed that skirted foundations significantly improved the bearing capacity compared to unskirted foundations. Bearing capacity increased with deeper skirt depths. Footings at the crest also showed improved bearing capacity. Footing embedment depth did not affect bearing capacity. The study provides insights into using skirted foundations to improve slope stability and bearing capacity
Stone columns are a versatile ground improvement technique used since the 1950s. They involve compacting coarse aggregate in columns in the ground to reinforce, densify and drain weak soils. Stone columns can improve bearing capacity, stability, reduce settlements and mitigate liquefaction. They work by transferring loads around them to stiffer columns, accelerating consolidation. Installation methods include ramming and vibro-replacement. Case studies show stone column embankments experience less settlement than untreated ground. In summary, stone columns are an effective ground improvement technique to strengthen weak soils.
Las Geomallas TriAx® distribuidas por EMIN Sistemas Geotecnicos y desarrolladas por Tensar International han demostrado ser extremadamente eficientes en confinar y estabilizar los agregados. Las Geomallas TriAx son una evolución natural de las geomallas biaxiales en términos de estabilización, ofreciendo incluso un mayor ahorro de coste.
Tensar mechanically stabilized layers can provide high-performance working platforms for surface mining operations by increasing load-bearing capacity over weak subgrades. These layers reduce maintenance costs by limiting rutting and potholes on haul roads. Tensar offers geogrid and geotextile products, as well as design and installation expertise, to stabilize unbound aggregate layers for roads, working areas, railway trackbeds, tailings lagoon caps, and leach pads.
El sistema Spectra de Tensar entrega a los constructores una forma innovadora de reducir los costos, tanto de agregados, como de asfalto; además, aumenta el valor y resistencia del producto final en la construcción de una carretera. Emin Sistemas Geotecnicos.
The document discusses how Tensar geogrids can be used to stabilize soils and reinforce structures for oil and gas infrastructure projects. Tensar geogrids provide major cost and time savings compared to traditional solutions by allowing thinner road and pad construction, reducing excavation needs, and increasing load bearing capacity even in extreme cold conditions. Their use can also reduce construction emissions by up to 50% through these material reductions.
La Autoridad de Tránsito Regional de Nueva Orleans (The New Orleans Regional Transit Authority) aplicó el Spectra® Rail System para reforzar una sección de 14 millas de la línea de tranvía de la histórica St. Charles Avenue.
“Minimizing time-consuming excavation requirements is a key advantage of the Spectra System with TriAx Geogrid,” says TIC regional manager Lars Nelson.
The Arizona Department of Transportation (ADOT) used the Spectra Roadway Improvement System with Tensar TriAx Geogrid on a test section of an Interstate 10 widening project to address weak subgrade soils. The soils exhibited very low shear strength and required extensive overexcavation under traditional methods. The test section placed one layer of TriAx Geogrid directly on the subgrade to bridge the saturated soils. This allowed construction of the section without significant overexcavation and provided equivalent performance to areas treated with traditional methods, demonstrating it as a more affordable and time-saving option.
A 1.25-mile section of a CSX rail line near Milstead, Alabama was experiencing excessive ballast settlement and required frequent track maintenance due to poor subgrade soil conditions. CSX considered three alternatives to rehabilitate the track: relocating the line, stabilizing the subgrade with geotextile, or reinforcing the ballast with geotextiles and geogrids. CSX chose the ballast reinforcement solution using Tensar BX1300 geogrids, which involved raising the track, installing geogrid and geotextile, and replacing the ballast. This solution allowed CSX to restore normal train operations at a lower cost than relocating the line.
Shortcreting has proved to be the best method for construction of curved surfaces. Domes are now much easier to construct with the advent of shotcrete technology. Tunnel linings are also becoming easy with this technology. Not only are these but there a wide range of applications where this technology has been a leading one. This technical paper includes the concept of shotcrete and how it differs from conventional concrete. It also enumerates the different types of process involved in shotcreting i.e. dry mix process and wet mix process. Advantages of shotcrete and its applications in various fields like tunneling, canals, buildings etc. are specified in detail. This paper presents an overview of shotcreting technology along with its applications.
DEFINITION OF SHOTCRETE:-
Shotcrete is a mortar or high performance concrete conveyed through a hose and pneumatically projected at high velocity onto a backing surface. It is the force of this spraying action that leads to compaction of the concrete or mortar which then forms layers of concrete to the required thickness. Shotcreting has been an acceptable way of placing cementitious material in a variety of applications.
Usually patented polypropylene fibers are included in the shotcrete which increases the cohesive nature of the shotcrete through mechanically binding the cementitious materials together. This mechanism reduces the rebound waste that occurs through the shotcreting process and these fibers also resist plastic shrinkage and cracking through their ability to enhance the early stage tensile strength of concrete.
Shotcrete also gives better surface finishes and reduces surface tearing on non- linear sections. Cementitious material containing the poly propylene fibers resist cycles of freezing and thawing and also reduces the chances of water and chemical penetrations.
Technical textiles in Central Public Works DepartmentDr K M SONI
The document discusses the use of technical textiles by the Central Public Works Department (CPWD) in India. CPWD undertakes major construction projects like buildings, roads, bridges, and sports infrastructure. It uses various technical textiles for scaffolding, architectural membranes, geosynthetics applications in geotech, buildtech and hometech. Specific technical textiles mentioned include geogrids, geotextiles, geomembranes and geocomposites which are included in the Schedule of Rates for roads, retaining walls, slope stabilization and embankments. Increased use of technical textiles is expected in the future as their benefits become more widely recognized.
Contracting authorities often call for pavement structures that will withstand traffic without
damage for long periods of time. When traffic is heavy, this requirement is generally met by
providing thick structures with a variety of layers of well-defined types and characteristics.
The conventional rule that the lowest-quality materials should be placed in the lower levels
and the higher-performance materials at the surface is disproved by a new structure designed
and developed by Eurovia.
Jaipur metro rail corporation summer training reportRajendra Jhurawat
The document provides an overview of the Jaipur Metro Rail project from Mansarovar to Badi Chaupar. It discusses the civil engineering aspects of the project including the viaduct and underground structures. It also covers relocation of affected structures, design of pre-stressed concrete bridges, and types of pre-stressing including pre-tensioning and post-tensioning. Lists of references are also included.
XiTRACK is a polyurethane ballast reinforcement that is used to solve track quality issues and reduce maintenance costs. It captures ballast stones in a durable polyurethane cage, giving the ballast engineered properties to act as a structural layer and withstand repeated train loading. XiTRACK is applied by spraying liquid polyurethane onto the ballast surface, where it sets in seconds to reinforce the ballast layer. This reinforcement reduces maintenance needs, lowers lifetime costs by preventing ballast attrition, and increases track availability by eliminating alignment issues.
The Triton coastal and waterway systems use innovative composite marine structures made of advanced geogrid and geotextile materials for erosion control and waterway construction projects. The systems include marine mattresses, filter mattresses, gabions, marine cells, and grid composites that can be used for applications like shoreline protection, foundations, channel linings, and bridge construction. Triton systems offer advantages over traditional materials like riprap in that they are durable, flexible, resistant to chemical and environmental degradation, and can use locally available fill materials, making them a cost-effective solution to coastal erosion and waterway issues.
This document discusses Tensar International Corporation's ADD3 Capacity Improvement Systems for optimizing waste containment facilities. The ADD3 Systems use geogrids and engineered designs to maximize landfill capacity and lifespan. They allow construction of landfill cells over marginal soils and expansion without increasing site boundaries. This increases containment volume and extends the facility's service life. The systems help reduce costs and assure long-term environmental security for waste management owners and engineers.
This document provides an overview of shotcrete technology. It defines shotcrete as cement, sand and fine aggregate concretes applied pneumatically under high velocity. Shotcrete can be classified as dry process or wet process based on how the materials are mixed and delivered. Some key advantages of shotcrete include its ability to form irregular surfaces and provide reinforcement. Shotcrete has various applications in construction, tunneling and retaining walls. It provides a strong, durable concrete material when applied correctly.
IRJET- Optimum Utilisation of Continuous Miner used for Pillar Extraction...IRJET Journal
This document discusses optimizing the use of continuous miners for pillar extraction in bord and pillar mining. It examines the performance of a continuous miner used in panel CMP-11A of an underground coal mine in India. The reliability of the continuous miner was found to be 89.87% with failures mainly due to issues with the gathering system, hydraulics, and conveyor. The document also describes the various roof support systems used in different conditions, such as at roadway intersections or areas with faults. Borehole data was collected and used to design support based on rock mass classification.
Modelling of Permanent Deformation on Flexible Pavement Using Accelerated Pav...IOSR Journals
Abstract: The two major distresses encountered on flexible pavement under Indian conditions are fracture
(cracking) and longitudinal permanent deformation (rutting) which affects the serviceability of pavement.
Accelerated Pavement Testing Facility (APTF) is a tool which is a vital link for testing and measuring full-scale
field behaviour of cracking and rutting of pavement at in-situ conditions. Recently, CSIR-Central Road
Research Institute (CRRI) in India has procured a linear Heavy Vehicle Simulator (HVS) type of APTF which is
presently being used for finding out the cracking and rutting behaviour of a flexible pavement consisting Dense
Bituminous Concrete (DBC) as wearing course and Dense Bituminous Macadam (DBM) as binder course apart
from the conventional granular layers above sub-grade.
The present paper deals with the development of a statistical model and its approach for pavement
rutting under numerous passes (bi-directional) for the layer specifications which are (i) 40 mm DBC (ii) 120
mm DBM (iii) 250 mm Wet Mix Macadam (WMM) and (iv) 300 mm Granular Sub-base (GSB) above the Subgrade,
which is an Indian Specification widely used for 30 Million Standard Axles (MSA) at 5% CBR. The
statistical model has been developed by observing / recording pavement surface profile using Laser
Profilometer (off board) for every 5,000 passes upto 50,000 passes, thereafter at every 10,000 passes upto
175,000 passes and then at every 25,000 passes upto 275,000 passes. The details of methodology adopted, load
applied, temperature and material properties have also been given in the paper.
Keywords: Flexible pavement, Rutting, Accelerated Pavement Testing Facility,Modelling,Profilometer
This document provides information on determining the abrasion and impact values of coarse aggregates according to testing standards. It describes the testing procedures, including using a Los Angeles abrasion machine to rotate aggregates with steel spheres for 500-1000 revolutions, and an impact testing machine to subject aggregates to 15 blows. The aggregates are then sieved and weighed to calculate the abrasion value based on weight loss and impact value based on the ratio of fines weight to total sample weight. Flexible pavements are described as those that reflect deformation through underlying layers, using materials like asphalt, while rigid pavements made of concrete are designed based on slab action and flexural strength.
Similar to Emin sg estabilizacion mecanica de balastos (20)
EMIN Sistemas Geotécnicos (EMIN SG). Catálogo control de erosión para protección de zonas inestable o taludes. Alta eficiencia. Productos de alta calidad.
Emin Sistemas Geotecnicos (EMIN SG). El sistema de Chance® TRÍPODE, ASOCIADO pilas helicoidales ya acreditados y conocidos Chance® ofrecer al mercado una solución innovadora destinado a los cimientos transmisión y telecomunicaciones, eliminando el uso de hormigón, sistema de montaje simple, corriendo bases dentro de unos días minutos.
O documento apresenta o sistema TRIPOD da empresa CHANCE®, uma subsidiária no Brasil da Hubbell. O sistema TRIPOD oferece fundações 100% metálicas para estruturas de energia e telecomunicações, dispensando o uso de concreto. As fundações podem ser montadas de forma simples e rápida, em poucos minutos, proporcionando alta produtividade com equipes menores e redução de custos.
Emin Sistemas Geotecnicos (EMIN SG). Harvey Hubbell fue el FUNDADOR, 1888. Él obtuvo por lo menor 45 patentes.
El socket eléctrico de encendido por cadena fue patentado en 1896 y su mas famoso invento, la clavija eléctrica fue patentada en 1904, esta invención hizo posible el desarrollo de aparatos eléctricos portátiles.
Este documento describe las cimentaciones helicoidales Chance como una solución para la instalación de torres de transmisión eléctrica. Las cimentaciones helicoidales Chance pueden instalarse rápidamente en varios tipos de suelos, incluso en condiciones adversas. Se instalan en horas en lugar de días y reducen los costos en comparación con las cimentaciones de concreto tradicionales. Las cimentaciones helicoidales Chance son una opción sostenible fabricada principalmente con materiales reciclables.
Emin Sistemas Geotecnicos (EMIN SG). A diferencia de hormigón, el sistema de pilotes helicoidal CHANCE® se puede instalar todo el año y en cualquier condición meteorológica. No hay que esperar para que se cure el hormigón y no se requiere excavación. Los pilotes helicoidales CHANCE® son ideales para las áreas inaccesible por la construcción convencional. Se instalan en casi cualquier tipo de terreno, incluyendo sitios con inclinaciones altas, llanuras sujetas a inundaciónes, glaciales y zonas pantanosas.
Emin Sistemas Geotecnicos (EMIN SG). Catálogo explicativo de los sistemas de anclaje de Hubbell y sus pilotes helicoidales para fundaciones y cimentaciones.
Emin Sistemas Geotecnicos (EMIN SG). Catálogo de sistemas de anclaje desarrollado por Hubbell para la aplicación de pilotes helicoidales en cimentaciones.
Emin Sistemas Geotecnicos (EMIN SG). Fundaciones e Instalación de Herramientas para Transmisión y Subestaciones de energía y electricidad con pilotes helicoidales.
Emin Sistemas Geotecnicos (EMIN SG).
Fundaciones helicoidales y herramientas de instalación para SOLAR y otras fuentes de energía renovables para sistemas de ingenieria.
El documento describe la construcción de una gran línea de transmisión eléctrica en Brasil llamada Proyecto Río Madeira. La línea transportará electricidad desde plantas hidroeléctricas en el noroeste de Brasil hacia las regiones más pobladas del sureste. Se utilizan pilotes helicoidales y tensores de anclaje Chance de Hubbell para soportar las torres de transmisión en diferentes tipos de terreno.
Emin Sistemas Geotecnicos (EMIN SG). Durante las primeras etapas del anclaje de tornillo, la resistencia de carga de un anclaje instalado no se pudo predecir con una precisión razonable. La información específica sobre las condiciones del suelo era escasa, haciendo que la selección del ancla fuera más o menos una conjetura. Con poca consideración por las variaciones del suelo y los efectos de los cambios climáticos estacionales o el drenaje, los suelos se clasificaron como "arena, arcilla, hardpan o pantano". No hubo ninguna explicación definitiva para tales condiciones del suelo.
Emin Sistemas Geotecnicos (EMIN SG). Lo que comenzó en 1912 como un emprendimiento para anclar postes telefónicos evolucionó en la creación de la fábrica líder en el mundo de pilotes helicoidales, anclajes y sistemas de retención terrestres. Como unidad comercial de Hubbell Power Systems, CHANCE® es una marca reconocida mundialmente como el productor más importante de productos de cimentación helicoidal diseñados para distintas aplicaciones, incluida la construcción de sistemas de energía solar y eólica.
Este documento describe los productos y sistemas de control de la erosión de Tensar International Corporation. Explica que Tensar ofrece una amplia gama de soluciones para el control de la erosión, incluidos mantos temporales y permanentes. También destaca que Tensar es líder en la industria y ofrece garantías exhaustivas para sus productos diseñados para prevenir la erosión y estabilizar el suelo.
EMIN Sistemas Geotecnicos. Desde el principio hasta el final del proyecto, los productos de control de sedimentos y erosión de Tensar lo mantendrán protegido hasta que logre el establecimiento de su vegetación.
El sistema GlasGrid distribuido por EMIN Sistemas Geotecnicos, incrementa la vida útil del pavimento reduciendo así los costos de mantenimiento y ciclo de vida.
North American Green fabrica una línea completa de productos enrollados de control de erosión que satisfacen las necesidades específicas de control de erosión y /o de refuerzo de vegetación de cualquier aplicación. Distribuido por EMIN Sistemas Geotecnicos.
EMIN Sistemas Geotecnicos ofrece los productos Tensar International. Los productos para el control de la erosión de aplicación hidráulica de Tensar, también conocidos como HECP (Hydraulic Erosion Control Products), son ideales para controlar la erosión y estimular el crecimiento de la vegetación en taludes con inclinaciones moderadas a extremas.
Geoceldas Envirogrid distribuidas en Chile y Sudamérica por EMIN Sistemas Geotécnicos. Ideal para suelos, fundaciones, erosión de taludes, terraplenes y mantenimiento de caminos inestables.
Redefining brain tumor segmentation: a cutting-edge convolutional neural netw...IJECEIAES
Medical image analysis has witnessed significant advancements with deep learning techniques. In the domain of brain tumor segmentation, the ability to
precisely delineate tumor boundaries from magnetic resonance imaging (MRI)
scans holds profound implications for diagnosis. This study presents an ensemble convolutional neural network (CNN) with transfer learning, integrating
the state-of-the-art Deeplabv3+ architecture with the ResNet18 backbone. The
model is rigorously trained and evaluated, exhibiting remarkable performance
metrics, including an impressive global accuracy of 99.286%, a high-class accuracy of 82.191%, a mean intersection over union (IoU) of 79.900%, a weighted
IoU of 98.620%, and a Boundary F1 (BF) score of 83.303%. Notably, a detailed comparative analysis with existing methods showcases the superiority of
our proposed model. These findings underscore the model’s competence in precise brain tumor localization, underscoring its potential to revolutionize medical
image analysis and enhance healthcare outcomes. This research paves the way
for future exploration and optimization of advanced CNN models in medical
imaging, emphasizing addressing false positives and resource efficiency.
International Conference on NLP, Artificial Intelligence, Machine Learning an...gerogepatton
International Conference on NLP, Artificial Intelligence, Machine Learning and Applications (NLAIM 2024) offers a premier global platform for exchanging insights and findings in the theory, methodology, and applications of NLP, Artificial Intelligence, Machine Learning, and their applications. The conference seeks substantial contributions across all key domains of NLP, Artificial Intelligence, Machine Learning, and their practical applications, aiming to foster both theoretical advancements and real-world implementations. With a focus on facilitating collaboration between researchers and practitioners from academia and industry, the conference serves as a nexus for sharing the latest developments in the field.
DEEP LEARNING FOR SMART GRID INTRUSION DETECTION: A HYBRID CNN-LSTM-BASED MODELgerogepatton
As digital technology becomes more deeply embedded in power systems, protecting the communication
networks of Smart Grids (SG) has emerged as a critical concern. Distributed Network Protocol 3 (DNP3)
represents a multi-tiered application layer protocol extensively utilized in Supervisory Control and Data
Acquisition (SCADA)-based smart grids to facilitate real-time data gathering and control functionalities.
Robust Intrusion Detection Systems (IDS) are necessary for early threat detection and mitigation because
of the interconnection of these networks, which makes them vulnerable to a variety of cyberattacks. To
solve this issue, this paper develops a hybrid Deep Learning (DL) model specifically designed for intrusion
detection in smart grids. The proposed approach is a combination of the Convolutional Neural Network
(CNN) and the Long-Short-Term Memory algorithms (LSTM). We employed a recent intrusion detection
dataset (DNP3), which focuses on unauthorized commands and Denial of Service (DoS) cyberattacks, to
train and test our model. The results of our experiments show that our CNN-LSTM method is much better
at finding smart grid intrusions than other deep learning algorithms used for classification. In addition,
our proposed approach improves accuracy, precision, recall, and F1 score, achieving a high detection
accuracy rate of 99.50%.
Harnessing WebAssembly for Real-time Stateless Streaming PipelinesChristina Lin
Traditionally, dealing with real-time data pipelines has involved significant overhead, even for straightforward tasks like data transformation or masking. However, in this talk, we’ll venture into the dynamic realm of WebAssembly (WASM) and discover how it can revolutionize the creation of stateless streaming pipelines within a Kafka (Redpanda) broker. These pipelines are adept at managing low-latency, high-data-volume scenarios.
KuberTENes Birthday Bash Guadalajara - K8sGPT first impressionsVictor Morales
K8sGPT is a tool that analyzes and diagnoses Kubernetes clusters. This presentation was used to share the requirements and dependencies to deploy K8sGPT in a local environment.
CHINA’S GEO-ECONOMIC OUTREACH IN CENTRAL ASIAN COUNTRIES AND FUTURE PROSPECTjpsjournal1
The rivalry between prominent international actors for dominance over Central Asia's hydrocarbon
reserves and the ancient silk trade route, along with China's diplomatic endeavours in the area, has been
referred to as the "New Great Game." This research centres on the power struggle, considering
geopolitical, geostrategic, and geoeconomic variables. Topics including trade, political hegemony, oil
politics, and conventional and nontraditional security are all explored and explained by the researcher.
Using Mackinder's Heartland, Spykman Rimland, and Hegemonic Stability theories, examines China's role
in Central Asia. This study adheres to the empirical epistemological method and has taken care of
objectivity. This study analyze primary and secondary research documents critically to elaborate role of
china’s geo economic outreach in central Asian countries and its future prospect. China is thriving in trade,
pipeline politics, and winning states, according to this study, thanks to important instruments like the
Shanghai Cooperation Organisation and the Belt and Road Economic Initiative. According to this study,
China is seeing significant success in commerce, pipeline politics, and gaining influence on other
governments. This success may be attributed to the effective utilisation of key tools such as the Shanghai
Cooperation Organisation and the Belt and Road Economic Initiative.
A SYSTEMATIC RISK ASSESSMENT APPROACH FOR SECURING THE SMART IRRIGATION SYSTEMSIJNSA Journal
The smart irrigation system represents an innovative approach to optimize water usage in agricultural and landscaping practices. The integration of cutting-edge technologies, including sensors, actuators, and data analysis, empowers this system to provide accurate monitoring and control of irrigation processes by leveraging real-time environmental conditions. The main objective of a smart irrigation system is to optimize water efficiency, minimize expenses, and foster the adoption of sustainable water management methods. This paper conducts a systematic risk assessment by exploring the key components/assets and their functionalities in the smart irrigation system. The crucial role of sensors in gathering data on soil moisture, weather patterns, and plant well-being is emphasized in this system. These sensors enable intelligent decision-making in irrigation scheduling and water distribution, leading to enhanced water efficiency and sustainable water management practices. Actuators enable automated control of irrigation devices, ensuring precise and targeted water delivery to plants. Additionally, the paper addresses the potential threat and vulnerabilities associated with smart irrigation systems. It discusses limitations of the system, such as power constraints and computational capabilities, and calculates the potential security risks. The paper suggests possible risk treatment methods for effective secure system operation. In conclusion, the paper emphasizes the significant benefits of implementing smart irrigation systems, including improved water conservation, increased crop yield, and reduced environmental impact. Additionally, based on the security analysis conducted, the paper recommends the implementation of countermeasures and security approaches to address vulnerabilities and ensure the integrity and reliability of the system. By incorporating these measures, smart irrigation technology can revolutionize water management practices in agriculture, promoting sustainability, resource efficiency, and safeguarding against potential security threats.
Literature Review Basics and Understanding Reference Management.pptxDr Ramhari Poudyal
Three-day training on academic research focuses on analytical tools at United Technical College, supported by the University Grant Commission, Nepal. 24-26 May 2024
Advanced control scheme of doubly fed induction generator for wind turbine us...IJECEIAES
This paper describes a speed control device for generating electrical energy on an electricity network based on the doubly fed induction generator (DFIG) used for wind power conversion systems. At first, a double-fed induction generator model was constructed. A control law is formulated to govern the flow of energy between the stator of a DFIG and the energy network using three types of controllers: proportional integral (PI), sliding mode controller (SMC) and second order sliding mode controller (SOSMC). Their different results in terms of power reference tracking, reaction to unexpected speed fluctuations, sensitivity to perturbations, and resilience against machine parameter alterations are compared. MATLAB/Simulink was used to conduct the simulations for the preceding study. Multiple simulations have shown very satisfying results, and the investigations demonstrate the efficacy and power-enhancing capabilities of the suggested control system.
2. Stabilisation of the ballast layer using Tensar®
TriAx®
geogrids can substantially delay track settlement
increasing periods between maintenance operations.
1. Reducing Ballast Deformation through the Mechanical
Stabilisation of the Ballast Layer
Based on the characteristic properties of Tensar geogrids and
geotextiles, Tensar Technology is widely adopted for ground
stabilisation and soil reinforcement problems, delivering real
savings in cost and time. We can help you apply Tensar
Technology to improve the bottom line on your project.
Tensar Technology – Proven
Practical Solutions and the
Know-How to Build them
2
Poor track geometry and a loss of vertical
and horizontal alignment of the rails is a
major reason for line speed restrictions and
track maintenance work. These can
significantly affect schedules and are
expensive and disruptive to the public and
the train operators.
Track maintenance, involving ballast
tamping or full ballast replacement, arises
not only on weak subgrades but also on
firmer supporting soils.
Mechanical stabilisation of ballast, using
Tensar geogrids, gives the railway engineer
a rapid and safe solution.
Tensar geogrids have been used to stabilise
track ballast since the early 1980s to
decrease maintenance costs and maintain
ride quality.
2 Major Application Areas for the use of Tensar TriAx® Ge
Mechanical stabilisation of the ballast layer to reduce the rate of track
settlement and hence increase the period between maintenance
operations with huge whole life benefits.
RESEARCH HAS DEMONSTRATED THAT TENSAR GEOGRIDS CAN:
Reduce the rate of ballast settlement
Maintain track geometry for longer
Extend the maintenance cycle by a factor of approximately 3
Function in ballast for more than 20 years
Reduce traffic-induced ballast degradation
Tensar TriAx® geogridBallast
Subgrade
3. 3
x® Geogrids within the Track Substructure
2. Improving Track Foundation through the Mechanical
Stabilisation of the Sub-Ballast Layer
When constructing track over soft
subgrade soils having a low bearing
capacity, it is necessary to improve the
foundation to support the ballast
effectively. This can involve a time
consuming chemical stabilisation of the
subgrade or deep excavation followed by
importation and placement of a thick and
expensive granular sub-ballast layer.
Introducing a Tensar mechanically
stabilised layer using TriAx® geogrids,
enables a significant reduction of
sub-ballast layer thickness for the same
bearing capacity.
This results in reduction of subgrade
excavation and spoil disposal and much
less imported sub-ballast fill, while still
achieving the target stiffness value
required for the support of the ballast.
Tensar has extensive experience in
mechanically stabilising sub-ballast layers,
especially in the upgrading of European
railway corridors, that has resulted in many
successful cost-effective installations.
Stabilisation of the granular sub-ballast layer to increase the bearing
capacity over soft subgrade results in significant thickness reductions
and savings in both the capital and environmental costs.
Tensar TriAx® geogridBallast
Subgrade
Granular sub-ballast
Track reconstruction over low bearing capacity subgrade soils using mechanically stabilised sub-ballast, (Bratislava, Slovakia).
4. 4
Tensar geogrids make a structural contribution to railway
trackbed. When granular fill material, such as ballast or
sub-ballast, is compacted over a Tensar geogrid, it partially
penetrates and projects through the apertures to create a
strong and positive interlock. This interlock enables the
geogrid to confine the fill and restrain the granular material
from lateral spread, which is a major cause of settlement of
railway track. This mechanism is critical in helping to
maintain the horizontal and vertical alignments of the rails.
Tensar stabiliation geogrids are produced with high tensile
stiffness which allows load to be developed at very low
strain. These polypropylene geogrids are manufactured with
dimensionally stable apertures. Matching the appropriate
geogrid aperture size with the particle sizes of the overlying
fill material is important to the stabilisation performance.
The essential features of Tensar geogrids, which are required
to ensure effective interlock, include the strength of the
junctions and the shape and stiffness of the ribs. The Tensar
manufacturing process produces a monolithic geogrid
structure with high junction strength and with ribs which
present a square and thick leading edge to the aggregate for
effective transfer of load.
How Tensar Stabilisation Geogrids Work
The interlock between the geogrid and the granular fill limits lateral
movement of particles even when dynamic loading is applied. In practice
this means that the settlement rate is reduced.
The characteristic cross-sectional shape of Tensar TriAx® ribs provides
bearing points for fill particles. The forces can then be transferred through
the rigid junctions.
The ribs present a thick, square, leading edge to create positive transfer of
load from the ballast to the geogrid.
Tensar geogrids are also available in a composite form where
a non-woven geotextile is bonded to the geogrid. The
composite products are particularly suitable when the
function of separation is needed together with stabilisation.
Tensar Geocomposites
A composite version of TriAx® is available incorporating a geotextile separator.
Tensar TriAx® geogrid
5. 5
1. Mechanical Stabilisation of Ballast to Reduce Maintenance Costs
Full scale model laboratory tests were carried out to
investigate the effect of Tensar geogrids in stabilising railway
ballast and controlling the settlement of the sleeper. On both
a weak and a firm subgrade, the geogrid reduced the rate of
sleeper settlement such that the sleeper could sustain over 4
times the number of load cycles, across the practicable range
of settlements. This indicated that there were great
advantages to using geogrid stabilisation for all railway track
in reducing settlement and reducing maintenance.
Installation of geogrid within the ballast (Belgium).
Research in Canada showed that by including Tensar geogrid over relatively weak and firm foundation soils maintenance life
increased by a factor of 4.9 and 4.75 respectively (after Bathurst, 1986*).
Early Laboratory Tests, Canada 1986
0
-100
-200
-300
-400
Permanentsleepersettlement(mm)
0 10 1,000 10,000 100,000 1,000,000100 10,000,000
25mm
Number of cycles
Infinite CBR (control)
CBR 39% (control)
CBR 1% (control)
Infinite CBR (stabilised)
CBR 39% (stabilised)
CBR 1% (stabilised)
4.9x 4.75x
6. 6
In the early 1990s British Rail Research investigated the use
of a Tensar geogrid to limit the progressive lateral
displacement of the ballast particles under repeated train
loading. This investigated the settlement and the rate of
deterioration of the vertical track geometry.
The full scale trial using a 40 tonne rolling load rig to simulate
2 million gross tonnes on the track, consisted of three tests
over a soft subgrade (E=10MPa). In two of the tests, the
geogrid was laid in the underlying ballast layer. The results of
these tests were then compared with a similar non-stabilised
test previously carried out over a very firm subgrade.
This work showed that the introduction of geogrid
reinforcement into the ballast over a soft subgrade can
provide a performance almost equal to a railway track placed
on a firm foundation.
Tensar geogrids were also shown to reduce the elastic
deflection by up to 40%. This benefit can be of considerable
value in reducing maintenance costs and disruptive delays in
replacing damaged track components such as insulated block
joints (IBJs) which are vulnerable to damage caused by rail
deformation.
Installation of Tensar geogrids into the ballast over soft subgrade significantly reduces settlement, making
it comparable with track on firm foundations (after Matharu, 1994*).
Research by British Rail, UK 1994
Research by British Rail demonstrated the maintenance benefit of Tensar geogrids.
0
Initial lift (mm)
0
10
20
30
40
Settlementaftertrafficof2Mtonnes(mm)
10 20 30 40 50
Firm subgrade Soft foundation
with Tensar geogrid
stabilisation
Soft foundation
without Tensar
stabilisation
Initial lift to
operational
level (mm)
Settlement (mm)
Rail track level
before
reinstatement
Rail track level
raised during
re-ballasting
Position after
(2M gross tonnes)
trafficking
Test 1: soft sub-structure
and no geogrid
Test 2: soft sub-structure
and geogrid 50mm above
Test 3: soft sub-structure
and geogrid 100mm above
Improvement
from Tensar
stabilisation
7. 7
A major UK research and development project led by the
University of Nottingham quantified the permanent
settlement of track and investigated the use of Tensar
geogrids to control the settlement of track ballast and
increase the periods between maintenance. The three-year
project concluded in 2006 and was part funded by a
£250,000 innovation award grant from the Royal Society.
The project involved experimental work and theoretical
modelling together with a major field trial and the
development of design guidance. The research was conducted
at the University with three commercial partners; Tensar
International, leading railway consultant Scott Wilson
Pavement Engineering Ltd and leading railway contractor
Carillion Rail. Network Rail (who own and operate Britain’s rail
infrastructure) was represented on the project Steering Group.
Initial work on a small element of railway track tested a
variety of geogrids to examine the influence on settlement
of grid stiffness, aperture size and geogrid rib profile. The
results identified the optimum rib pitch for interlock with
standard ballast stone grading. The performance was found
to be relatively insensitive to the geogrid depth within the
ballast.
RESULTS DEMONSTRATED THAT THE FOLLOWING
GEOGRID PROPERTIES ARE ALSO IMPORTANT:
Strong junction strength (>95% efficiency)
High tensile stiffness at low strain levels
Rib thickness
Square edged rib profile
Results from the Nottingham University Railway Test Facility (RTF) show that Tensar geogrids provide
approximately 2.5 times increase in number of axle passes for same settlement (after Brown et al, 2006*).
The Nottingham Rail Test Facility (RTF) allows a full-scale
section of rail track, three sleepers in length, to be tested.
Dynamic loading is provided by three hydraulic actuators to
simulate the passing of a rolling stock axle. Three separate
installations, one control and two geogrid stabilised, were
tested to a million cycles. In one stabilised installation the
geogrid was placed at the base of the ballast and in the other
the geogrid was raised slightly above the base.
Settlement was measured and the results confirmed the
findings from smaller scale composite element tests (CET).
The results showed that use of Tensar large aperture geogrid
could increase the intervals between maintenance
interventions by a factor of at least 2.5. Simulated train loading at The Nottingham University RTF.
Research at The University of Nottingham, UK 2006
Tensar Geogrid Reduces Maintenance
0
2
4
6
8
10
12
14
Settlement(mm)
Number of cycles
0 200,000 400,000 600,000 800,000 1,000,000
Non-stabilised
Stabilised with Tensar geogrid
Over 2.5x
8. 8
A demonstration project organised by Network Rail on the
busy West Coast Main Line (WCML) between London and
Scotland has confirmed the findings from the Nottingham
laboratory research. An 800m section of track at Coppull
Moor had a history of poor geometry and high maintenance.
Network Rail decided to reconstruct this length of track with
new ballast and sleepers. The demonstration was split into
four sections; two control sections and two with Tensar
geogrid ballast stabilisation.
Network Rail has regularly monitored standard deviation (SD)
of the vertical deformation of the track using their high speed
track recording coach (HSTRC). There was much historical
data with which to compare the performance of the stabilised
and non-stabilised sections of the latest renewal.
Network Rail has found that the performance of the Tensar
stabilised sections shows a significant improvement. Analysis
of the data indicates that Tensar is extending the
maintenance life compared with the conventional solution by
between 2 and 4 times.
The detailed record from the HSTRC monitoring (shown
below) demonstrates dramatically how, for more than 10
years, this section of track had required almost continuous
speed restrictions despite maintenance typically twice a year.
However after the renewal in late 2004, using geogrid to
stabilise the ballast, both the reduction in the magnitude of
SD as well as the rate of deterioration are likely to result in at
least three years with neither maintenance nor speed
restriction.
Monitored Field Demonstrations, Network Rail, UK
WCML trial showing reduced rate of track quality deterioration following geogrid installation
(after Sharpe et al, 2006*).
Network Rail’s Approach to Mechanical Stabilisation of Ballast in
the UK
Network Rail has granted
Tensar geogrids full product
acceptance in accordance with
The Code of Practice.
1994
Year
1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008
0
1
2
3
4
5
6
SDover35M(mm)
With Tensar
geogrid stabilisation
Non-stabilised
Track rehabilitation
Tensar ballast
stabilisation
introduced here
Limit for
imposing
speed
restrictions
Based on the above evidence, Network Rail is
extensively using Tensar geogrid to extend
the maintenance life for track renewals over
problem formations. Tensar geogrids are also
being used at transition zones between
widely different support stiffness formations,
to mitigate the effect of differential
settlement. This can occur for example at the
run-on and run-off at under bridges.
Network Rail’s current Code of Practice on
Formation Treatments, R/SP/TRK/9039,
acknowledges the structural contribution from an
approved geogrid. This code, coupled with a product
acceptance certificate allows significantly lower
dynamic sleeper support stiffness values
for track on geogrid stabilised ballast compared with
conventional unstabilised ballast. In effect, the presence of
the geogrid allows thickness reductions to the trackbed depth
under the sleeper.
Tensar TriAx® TX190L geogrids have
been granted Network Rail
Product Acceptance Certification
(Number PA05 157/100470) for
the Structural Stabilisation of
Ballasted Trackbed.
9. 9
Tensar geogrids have been used to stabilise ballast for almost
30 years and some monitoring of their condition, in the field,
has been possible.
At a site known as Shirland in the UK, the geogrid was
installed in 1988 and in collaboration with the track operator
Network Rail, geogrid samples were retrieved in 1997 and
2006. Since installation the railway had been trafficked by
some 200 million gross tons of both freight and passenger
trains. An assessment of abrasion was made by examining
the tensile strength properties of a geogrid that was placed
approximately 225mm below sleeper bottom. The diagram
shows that the tensile strength properties have been
maintained and the geogrid remains stronger and stiffer than
the quality control standard for the Tensar geogrid that was
supplied to the project. Abrasion effects are negligible.
This is evidence that in the harsh environment of railway
ballast, Tensar has proved that the service life will extend
well beyond twenty years.
For the project itself, it is a problem solved. Before the
maintenance work, the line needed maintenance several
times per year. The records show that maintenance has been
reduced to a fraction of the former level. The cost benefit to
railway operators speaks for itself.
Durability in Ballast
QCstrength(kN/m)
Quality control limit
1988 After 9 years After 18 years
After 18 years, Tensar geogrid retains its quality control
strength.
10. 2. Mechanical Stabilisation of Sub-Ballast to Reduce Maintenance Costs
Tensar International has developed the mechanical
stabilisation of both sub-base and railway sub-ballast.
A proven performance has been demonstrated in numerous
trials, demonstrations and research projects.
The resulting sub-ballast layer will provide significant savings
in construction costs.
The thickness and structural performance of sub-ballast, over
weak subgrades, also ensures that the ballast layer has a
sustained quality of support and maintenance needs can
reduce significantly.
Tensar TriAx™ geogrids installed under the granular sub-ballast layer to increase bearing capacity (Belgium).
Almost 30 Years Experience in Mechanically Stabilising Granular Fill
DEUTSCHE BAHN, BERLIN-MUNICH LINE
The German Rail Authorities Deutsche Bahn (DB) carried out a
monitored trial during the widening of the Berlin-Munich line
between Hochstadt and Probstzella where the subgrade was
very soft, with a modulus Eu of 7-15 MPa.
Trial sections of 400mm and 600mm sub-ballast thickness
were constructed. Half of each section included Tensar
geogrid stabilisation.
Demonstration Projects in Europe
PLATE BEARING TESTS ON TOP OF THE
SUB-BALLAST SHOWED:
Tensar geogrid stabilisation doubled the modulus of a
sub-ballast layer
Tensar allowed a 33% reduction in sub-ballast thickness,
ie the modulus of a 400mm layer with Tensar was
equivalent to a 600mm non-stabilised thickness
10
120
100
80
60
40
20
0
EV2modulus(kN/m)
Non-stabilised
Stabilised with
Tensar biaxial
Sub-ballast thickness (mm)
400mm 600mm
11. 11
DEUTSCHE BAHN, COLOGNE
On a monitored project in Cologne in 2003, the inclusion of a
Tensar geocomposite over a soft formation permitted a
reduction in sub-ballast thickness from 1050mm to 700mm,
while maintaining the target modulus of 120MPa as the
ballast support value.
SLOVAKIA, BRATISLAVA-TRNAVA LINE
On the Bratislava to Trnava line in Slovakia,
the client used a Tensar mechanically
stabilised layer to achieve the UIC standard
minimum support modulus of 50MPa on
top of the sub-ballast.
Plate loading tests were conducted on site
to examine the validity of the design. The
following results were obtained:
Tensar geogrids for soil reinforcement have Network Rail Product Acceptance Certification (Number PA05/175 & 177) for railway
embankments, slope repairs and reinforced soil applications.
*All technical references can be obtained from Tensar.
Ballast E = 120 MPa
1050mm sub-ballast
700mm sub-ballast
Subgrade, Eu = 10 MPa
Non-stabilised and stabilised designs
Sleeper
Ballast
Tensar Mechanically Stabilised Layer
Subgrade
Target
modulus
80 MPa
50 MPa
Under side of sleeper
Top of msl
The design was for a Tensar
mechanically stabilised layer
(msl) of a specified thickness
incorporating Tensar geogrid.
100
90
80
70
60
50
40
30
20
10
0
EV2modulus(MPa)
Modulus on subgrade
Modulus on top of Tensar
stabilised sub-ballast
50 MPa
target
1 5 9
Test location
The Tensar solution achieved and exceeded the target.