This document discusses soil investigation for foundation engineering. It describes various methods for exploring soils, including geophysical tests, test pits, hand augers, wash boring, and rotary drilling. It emphasizes the importance of accurately characterizing subsurface soils, as soil properties can vary significantly within a site. A good soil investigation provides data on soil type, stratigraphy, groundwater, and other properties needed for foundation design. The number and depth of boreholes depends on factors like site geology and the structure's loads.
1. The bearing capacity of a foundation refers to the ability of the soil to carry the loads from structures placed on it without shear failure or excessive settlement.
2. Terzaghi's bearing capacity theory separates the failure zone under a foundation into triangular and radial shear zones, and considers the equilibrium of forces within these zones to calculate the ultimate bearing capacity.
3. The allowable bearing capacity is calculated by applying a safety factor to the ultimate capacity to avoid shear failure. Settlement criteria may further limit the allowable capacity.
This document provides an overview of the reorganization of ACI 318 from the 2011 to the 2014 version. Some key points:
- ACI 318 was first published in 1910 and has undergone numerous revisions to expand and improve requirements. The 2011 version contained over 2,500 provisions.
- For the 2014 version, the committee undertook a major reorganization based on feedback that engineers wanted information grouped by structural element for easier use.
- The new organization groups chapters into general, systems, members, joints/connections, toolbox, and construction sections. Individual element chapters now contain all relevant design and detailing requirements.
- The goal of the reorganization was to make it quicker and easier for engineers to find all
El documento describe los conceptos de empuje activo y pasivo en suelos, y cómo calcularlos. Explica que el empuje activo depende del movimiento de la pared de contención y es máximo cuando el suelo alcanza su límite de rotura en todos los puntos. El empuje pasivo es máximo cuando el suelo alcanza su estado plástico límite en todos los puntos. También cubre cómo la saturación del suelo afecta la presión sobre el muro.
Rock anchors have been used in the United States since the early 1960s as temporary tie backs and permanently in dams since 1968. Permanent anchors are designed to last up to 100 years with sophisticated corrosion protection systems. There are various types of permanent anchors including multi-strand systems with up to 27 strands and over 4000 kN of tension capacity, as well as permanent stressbar anchors and rock bolts used in infrastructure retention. Proper corrosion protection involving encapsulation and sheathing is necessary for permanent anchors to achieve their long design life.
This document provides an overview of pile foundations, including different types of piles classified by material, length, orientation, and installation method. Piles transfer structural loads to deeper firm soil layers when the top soil is loose, soft, or swelling. Piles are long slender columns that can be driven, bored, or cast in place using materials like concrete, steel, or timber. Driven piles compact the surrounding soil to increase capacity, while cast-in-place piles are constructed by drilling holes and filling with concrete to avoid disturbing soil. The document discusses advantages and disadvantages of different pile types.
Trabajo didactico relacionado con el ensayo de crb de los suelos, para conocer su resistencia al corte, la resistencia de pentracion de un suelo, la capacidad soporte del mismo
Los suelos expansivos son aquellos que experimentan cambios significativos de volumen en respuesta a variaciones en su contenido de agua. La arcilla expansiva más problemática es la montmorillonita, la cual tiene una gran capacidad de intercambio catiónico y hinchamiento. El hinchamiento diferencial de los suelos expansivos debajo de las cimentaciones puede causar daños a las estructuras. El potencial de hinchamiento depende de factores como el tipo y cantidad de minerales, densidad, condiciones de carga, estructura del suelo, contenido
This document discusses soil investigation for foundation engineering. It describes various methods for exploring soils, including geophysical tests, test pits, hand augers, wash boring, and rotary drilling. It emphasizes the importance of accurately characterizing subsurface soils, as soil properties can vary significantly within a site. A good soil investigation provides data on soil type, stratigraphy, groundwater, and other properties needed for foundation design. The number and depth of boreholes depends on factors like site geology and the structure's loads.
1. The bearing capacity of a foundation refers to the ability of the soil to carry the loads from structures placed on it without shear failure or excessive settlement.
2. Terzaghi's bearing capacity theory separates the failure zone under a foundation into triangular and radial shear zones, and considers the equilibrium of forces within these zones to calculate the ultimate bearing capacity.
3. The allowable bearing capacity is calculated by applying a safety factor to the ultimate capacity to avoid shear failure. Settlement criteria may further limit the allowable capacity.
This document provides an overview of the reorganization of ACI 318 from the 2011 to the 2014 version. Some key points:
- ACI 318 was first published in 1910 and has undergone numerous revisions to expand and improve requirements. The 2011 version contained over 2,500 provisions.
- For the 2014 version, the committee undertook a major reorganization based on feedback that engineers wanted information grouped by structural element for easier use.
- The new organization groups chapters into general, systems, members, joints/connections, toolbox, and construction sections. Individual element chapters now contain all relevant design and detailing requirements.
- The goal of the reorganization was to make it quicker and easier for engineers to find all
El documento describe los conceptos de empuje activo y pasivo en suelos, y cómo calcularlos. Explica que el empuje activo depende del movimiento de la pared de contención y es máximo cuando el suelo alcanza su límite de rotura en todos los puntos. El empuje pasivo es máximo cuando el suelo alcanza su estado plástico límite en todos los puntos. También cubre cómo la saturación del suelo afecta la presión sobre el muro.
Rock anchors have been used in the United States since the early 1960s as temporary tie backs and permanently in dams since 1968. Permanent anchors are designed to last up to 100 years with sophisticated corrosion protection systems. There are various types of permanent anchors including multi-strand systems with up to 27 strands and over 4000 kN of tension capacity, as well as permanent stressbar anchors and rock bolts used in infrastructure retention. Proper corrosion protection involving encapsulation and sheathing is necessary for permanent anchors to achieve their long design life.
This document provides an overview of pile foundations, including different types of piles classified by material, length, orientation, and installation method. Piles transfer structural loads to deeper firm soil layers when the top soil is loose, soft, or swelling. Piles are long slender columns that can be driven, bored, or cast in place using materials like concrete, steel, or timber. Driven piles compact the surrounding soil to increase capacity, while cast-in-place piles are constructed by drilling holes and filling with concrete to avoid disturbing soil. The document discusses advantages and disadvantages of different pile types.
Trabajo didactico relacionado con el ensayo de crb de los suelos, para conocer su resistencia al corte, la resistencia de pentracion de un suelo, la capacidad soporte del mismo
Los suelos expansivos son aquellos que experimentan cambios significativos de volumen en respuesta a variaciones en su contenido de agua. La arcilla expansiva más problemática es la montmorillonita, la cual tiene una gran capacidad de intercambio catiónico y hinchamiento. El hinchamiento diferencial de los suelos expansivos debajo de las cimentaciones puede causar daños a las estructuras. El potencial de hinchamiento depende de factores como el tipo y cantidad de minerales, densidad, condiciones de carga, estructura del suelo, contenido
214 77 recommended practice for evaluation of strength tesMOHAMMED SABBAR
This document provides guidelines for analyzing the results of concrete strength tests using statistical methods. It discusses sources of variation in concrete strength, including materials properties, testing methods, and construction practices. Statistical analysis can help evaluate whether the concrete meets strength requirements while accounting for natural variability. The document recommends maintaining strict quality control, using random sampling, and following statistical procedures to properly interpret concrete strength test results.
Mecanica de suelos i eslage (17 18) (1)JUAN LINARES
El documento describe los diferentes tipos de suelos desde la perspectiva de la mecánica de suelos, incluyendo suelos no cohesivos como gravas y arenas, suelos cohesivos como arcillas, y suelos orgánicos como turba. También describe la estructura de los suelos como la distribución y ordenamiento de las partículas, y cómo esta estructura afecta las propiedades de los suelos y su respuesta a cargas y cambios de humedad. Finalmente, explica las fuerzas entre las partículas de suelo
Design of RCC slab two way continuous supportedBhavik A Shah
This document provides information about the design of reinforced concrete slabs. It discusses two-way continuous slabs supported on beams. It provides details on slab thickness calculation, maximum bar diameter and spacing allowed, cover requirements, and curtailment of reinforcement near supports. It then presents an example problem of designing a one-way continuous slab for a hall with given dimensions and material properties. Reinforcement details like main and distribution bar sizes and spacing are also specified for different regions of the slab.
El documento presenta un resumen del ensayo CBR (California Bearing Ratio), el cual mide la resistencia de un terreno y su capacidad para soportar cargas de tráfico vehicular. El ensayo describe las normas aplicables, el procedimiento en laboratorio, y cómo interpretar los resultados. Se toman muestras de suelo, se compactan a diferentes densidades y se miden sus índices CBR tras aplicar cargas de penetración controladas. Esto permite estimar la capacidad portante del terreno para el diseño de pavimentos.
estudio de los estribos que se puede presentarse en los suelos tanto como el nivel freatico del agua y prodecder a calcular los esfuerzos que se presentan
This document discusses seepage pressure and flow through earthen dams. It explains that seepage pressure is the force per unit volume exerted by flowing water on the soil, acting along the flow line. It describes how flow nets can be used to determine seepage pressure at any point. The document also discusses the phreatic line (seepage line) and how its position within a dam is important for stability. It provides details on analyzing seepage flow through homogeneous earthen dams using confocal parabolas with a common focus.
1. The document describes the direct shear test procedure used to determine the shear strength properties of soils. It involves applying a normal load to a soil sample confined in a shear box and measuring the shear stress and displacement as the sample is sheared.
2. The direct shear test can be conducted as unconsolidated-undrained (UU), consolidated-undrained (CU), or consolidated-drained (CD) tests. Shear strength parameters such as cohesion and friction angle are determined from graphs of shear stress versus shear displacement and shear stress versus normal stress.
3. The purpose of the direct shear test is to examine the shear strength of soil samples along
Class notes of Geotechnical Engineering course I used to teach at UET Lahore. Feel free to download the slide show.
Anyone looking to modify these files and use them for their own teaching purposes can contact me directly to get hold of editable version.
Cracks on concrete.
How to catergorized cracks on newly poured concrete
Thermal cracks
Mass concrete
Fresh concrete
Cracks on concrete have many causes. They may affect appearance only, or it may indicate significant structural distress
Non destructive testing on concrete ( ndt )RakeshRaki94
This document discusses non-destructive testing methods for concrete, including various surface hardness, rebound hammer, penetration, dynamic, combined, radioactive, magnetic, and acoustic emission techniques. It focuses on rebound hammer and pulse velocity methods. For rebound hammers, it describes how the hammer impacts the surface and the rebound number indicates hardness. Pulse velocity methods measure the time of travel for ultrasonic or mechanical pulses, with direct, indirect, and surface transmission techniques. Suggested velocity criteria are provided to assess concrete quality.
The document describes Indian Standard code IS:2911 (Part I/Sec I) - 1979 which provides guidelines for the design and construction of driven cast in-situ concrete pile foundations. It covers necessary considerations for pile type, size, installation depth, load testing, and other factors based on site conditions and project requirements. Subsurface investigation data on soil properties, groundwater levels, and chemical testing is required to properly design and install pile foundations. The standard has been revised to incorporate recent developments and separate pile foundation types into distinct sections for ease of use.
This document discusses the importance of soil testing for construction projects. Soil testing allows builders to verify soil stability and compaction to ensure structures remain strong. Various tests examine density, moisture content, and maximum compaction. Geotechnical engineers use soil analysis to inform recommendations for grading, drainage, foundations and more. Proper soil investigation and testing are essential parts of the planning process for construction.
1. La prueba de compresión simple determina la resistencia al esfuerzo cortante de un suelo mediante la aplicación de un esfuerzo axial para evaluar la carga que puede soportar sin fallar.
2. Se utiliza para diseñar cimentaciones en obras civiles como edificios y puentes e interpretar la estabilidad de taludes.
3. Los parámetros de resistencia obtenidos, como el esfuerzo desviador y la cohesión, permiten comparar la resistencia de diferentes suelos.
Este documento describe los métodos para calcular la capacidad de carga de cimentaciones superficiales según la teoría de Terzaghi. Explica los factores que afectan la capacidad de carga como la profundidad de desplante, el nivel freático, el ángulo de fricción del suelo, y presenta ejemplos numéricos para ilustrar los cálculos.
SPT, SCPT, and DCPT Correlation for SC, CL, and SM-SC Soils: A Case Study of ...Samirsinh Parmar
SPT, SCPT, and DCPT Correlation for SC, CL, and SM-SC Soils: A Case Study of Nadiad Soil,Standard Penetration Test, Dynamic Cone Penetration Test, Static Cone Penetration Test, Sand, Silt, Correlation
Chapter 4 soil composition & engineering propertiesStan Vitton
The document discusses soil composition and engineering properties. It describes two groups of factors that influence soil properties: compositional factors like mineral types and amounts, pore water, and organic matter; and environmental factors like water content, density, and temperature. Quantitatively determining soil behavior based on these factors is difficult due to complex natural compositions and interactions between constituents. The document then discusses approaches to studying relationships between composition and properties using natural soils or synthetic mixtures, and challenges in those approaches. It also describes how granular soil properties depend on particle characteristics like size, shape, stiffness, and strength.
The document discusses site investigation, which involves gathering subsurface information about a proposed construction project location. It describes the purpose, scope, and stages of a site investigation. The typical stages are a desk study, preliminary investigation including some boreholes, a detailed investigation with more boreholes and sampling, and monitoring during construction. Common investigation methods discussed are the standard penetration test, cone penetration test, and sampling techniques.
Lego was founded in Denmark in 1949 and has since developed a wide range of toy products across different age ranges through its 78-year history. It produces construction toys like trains, planes, cars, ships, and cities. For younger kids aged 0-4, Lego toys are designed to help build skills, encourage imagination and creativity, and improve dexterity. The company also focuses on corporate social responsibility through ensuring workplace health and safety, as well as engaging with and supporting local communities.
Coal is a black or brown sedimentary rock formed from the compression of dead plant matter over millions of years. It exists in various forms from peat to anthracite depending on the level of compression. Coal provides over 7 million jobs and is a primary source of electricity generation worldwide due to its low cost and abundance. However, coal mining and combustion produce environmental impacts like acid rain, pollution of water sources, and health hazards. While coal fueled the Industrial Revolution, its use now needs to decline to avoid catastrophic climate change, making a transition to renewable energy sources necessary.
214 77 recommended practice for evaluation of strength tesMOHAMMED SABBAR
This document provides guidelines for analyzing the results of concrete strength tests using statistical methods. It discusses sources of variation in concrete strength, including materials properties, testing methods, and construction practices. Statistical analysis can help evaluate whether the concrete meets strength requirements while accounting for natural variability. The document recommends maintaining strict quality control, using random sampling, and following statistical procedures to properly interpret concrete strength test results.
Mecanica de suelos i eslage (17 18) (1)JUAN LINARES
El documento describe los diferentes tipos de suelos desde la perspectiva de la mecánica de suelos, incluyendo suelos no cohesivos como gravas y arenas, suelos cohesivos como arcillas, y suelos orgánicos como turba. También describe la estructura de los suelos como la distribución y ordenamiento de las partículas, y cómo esta estructura afecta las propiedades de los suelos y su respuesta a cargas y cambios de humedad. Finalmente, explica las fuerzas entre las partículas de suelo
Design of RCC slab two way continuous supportedBhavik A Shah
This document provides information about the design of reinforced concrete slabs. It discusses two-way continuous slabs supported on beams. It provides details on slab thickness calculation, maximum bar diameter and spacing allowed, cover requirements, and curtailment of reinforcement near supports. It then presents an example problem of designing a one-way continuous slab for a hall with given dimensions and material properties. Reinforcement details like main and distribution bar sizes and spacing are also specified for different regions of the slab.
El documento presenta un resumen del ensayo CBR (California Bearing Ratio), el cual mide la resistencia de un terreno y su capacidad para soportar cargas de tráfico vehicular. El ensayo describe las normas aplicables, el procedimiento en laboratorio, y cómo interpretar los resultados. Se toman muestras de suelo, se compactan a diferentes densidades y se miden sus índices CBR tras aplicar cargas de penetración controladas. Esto permite estimar la capacidad portante del terreno para el diseño de pavimentos.
estudio de los estribos que se puede presentarse en los suelos tanto como el nivel freatico del agua y prodecder a calcular los esfuerzos que se presentan
This document discusses seepage pressure and flow through earthen dams. It explains that seepage pressure is the force per unit volume exerted by flowing water on the soil, acting along the flow line. It describes how flow nets can be used to determine seepage pressure at any point. The document also discusses the phreatic line (seepage line) and how its position within a dam is important for stability. It provides details on analyzing seepage flow through homogeneous earthen dams using confocal parabolas with a common focus.
1. The document describes the direct shear test procedure used to determine the shear strength properties of soils. It involves applying a normal load to a soil sample confined in a shear box and measuring the shear stress and displacement as the sample is sheared.
2. The direct shear test can be conducted as unconsolidated-undrained (UU), consolidated-undrained (CU), or consolidated-drained (CD) tests. Shear strength parameters such as cohesion and friction angle are determined from graphs of shear stress versus shear displacement and shear stress versus normal stress.
3. The purpose of the direct shear test is to examine the shear strength of soil samples along
Class notes of Geotechnical Engineering course I used to teach at UET Lahore. Feel free to download the slide show.
Anyone looking to modify these files and use them for their own teaching purposes can contact me directly to get hold of editable version.
Cracks on concrete.
How to catergorized cracks on newly poured concrete
Thermal cracks
Mass concrete
Fresh concrete
Cracks on concrete have many causes. They may affect appearance only, or it may indicate significant structural distress
Non destructive testing on concrete ( ndt )RakeshRaki94
This document discusses non-destructive testing methods for concrete, including various surface hardness, rebound hammer, penetration, dynamic, combined, radioactive, magnetic, and acoustic emission techniques. It focuses on rebound hammer and pulse velocity methods. For rebound hammers, it describes how the hammer impacts the surface and the rebound number indicates hardness. Pulse velocity methods measure the time of travel for ultrasonic or mechanical pulses, with direct, indirect, and surface transmission techniques. Suggested velocity criteria are provided to assess concrete quality.
The document describes Indian Standard code IS:2911 (Part I/Sec I) - 1979 which provides guidelines for the design and construction of driven cast in-situ concrete pile foundations. It covers necessary considerations for pile type, size, installation depth, load testing, and other factors based on site conditions and project requirements. Subsurface investigation data on soil properties, groundwater levels, and chemical testing is required to properly design and install pile foundations. The standard has been revised to incorporate recent developments and separate pile foundation types into distinct sections for ease of use.
This document discusses the importance of soil testing for construction projects. Soil testing allows builders to verify soil stability and compaction to ensure structures remain strong. Various tests examine density, moisture content, and maximum compaction. Geotechnical engineers use soil analysis to inform recommendations for grading, drainage, foundations and more. Proper soil investigation and testing are essential parts of the planning process for construction.
1. La prueba de compresión simple determina la resistencia al esfuerzo cortante de un suelo mediante la aplicación de un esfuerzo axial para evaluar la carga que puede soportar sin fallar.
2. Se utiliza para diseñar cimentaciones en obras civiles como edificios y puentes e interpretar la estabilidad de taludes.
3. Los parámetros de resistencia obtenidos, como el esfuerzo desviador y la cohesión, permiten comparar la resistencia de diferentes suelos.
Este documento describe los métodos para calcular la capacidad de carga de cimentaciones superficiales según la teoría de Terzaghi. Explica los factores que afectan la capacidad de carga como la profundidad de desplante, el nivel freático, el ángulo de fricción del suelo, y presenta ejemplos numéricos para ilustrar los cálculos.
SPT, SCPT, and DCPT Correlation for SC, CL, and SM-SC Soils: A Case Study of ...Samirsinh Parmar
SPT, SCPT, and DCPT Correlation for SC, CL, and SM-SC Soils: A Case Study of Nadiad Soil,Standard Penetration Test, Dynamic Cone Penetration Test, Static Cone Penetration Test, Sand, Silt, Correlation
Chapter 4 soil composition & engineering propertiesStan Vitton
The document discusses soil composition and engineering properties. It describes two groups of factors that influence soil properties: compositional factors like mineral types and amounts, pore water, and organic matter; and environmental factors like water content, density, and temperature. Quantitatively determining soil behavior based on these factors is difficult due to complex natural compositions and interactions between constituents. The document then discusses approaches to studying relationships between composition and properties using natural soils or synthetic mixtures, and challenges in those approaches. It also describes how granular soil properties depend on particle characteristics like size, shape, stiffness, and strength.
The document discusses site investigation, which involves gathering subsurface information about a proposed construction project location. It describes the purpose, scope, and stages of a site investigation. The typical stages are a desk study, preliminary investigation including some boreholes, a detailed investigation with more boreholes and sampling, and monitoring during construction. Common investigation methods discussed are the standard penetration test, cone penetration test, and sampling techniques.
Lego was founded in Denmark in 1949 and has since developed a wide range of toy products across different age ranges through its 78-year history. It produces construction toys like trains, planes, cars, ships, and cities. For younger kids aged 0-4, Lego toys are designed to help build skills, encourage imagination and creativity, and improve dexterity. The company also focuses on corporate social responsibility through ensuring workplace health and safety, as well as engaging with and supporting local communities.
Coal is a black or brown sedimentary rock formed from the compression of dead plant matter over millions of years. It exists in various forms from peat to anthracite depending on the level of compression. Coal provides over 7 million jobs and is a primary source of electricity generation worldwide due to its low cost and abundance. However, coal mining and combustion produce environmental impacts like acid rain, pollution of water sources, and health hazards. While coal fueled the Industrial Revolution, its use now needs to decline to avoid catastrophic climate change, making a transition to renewable energy sources necessary.
This document tests the maximum number of slides that can be uploaded to Slideshare by adding slides with incrementing numbers from 1 to 88888888. It concludes with a final slide stating "The End".
This resume summarizes the professional experience of Vamshi Kiran, who has over 10 years of experience in IT service management, operations, project management, and critical incident management. The resume lists roles at NetApp India Pvt Ltd from 2012-2013 as Release, Problem & Recovery Manager and Release / Project Manager. Previous roles were at IBM (India) Pvt. Ltd. from 2009-2012 including Global Major Incident Manager and Process Lead – EMEA projects. Earlier experience includes roles at Avishk Globalisers from 2006-2008 and Hinduja TMT from 2003-2005. The resume highlights experience in incident, problem, change and release management as well as asset and configuration management.
9 17 fujisawa et al -seags e journal 2013-06chakfarmer
The document discusses an experimental study that investigated the relationship between seepage force and the velocity of sand particles during sand boiling. The study used silica sand and measured the migration velocities of seepage water and sand particles by calculating discharge amounts. The results revealed that:
1) The equilibrium of forces (gravity, buoyancy, fluid-particle interaction) can be used to estimate velocities of sand particles subjected to upward seepage flow.
2) The seepage force needed for horizontal transport of sand tends to decrease as the velocity of sand particles increases.
3) Previous studies on seepage failure focused on critical hydraulic gradients or velocities, but this study provides insights into how sand transport develops during
VSIP-FMS provides facilities management services like cleaning, landscaping, and maintenance to industrial parks and factories. Their CEO welcomes customers and emphasizes that customer success is their success. They aim to keep environments clean, green, and minimize interruptions to utilities through comprehensive FM solutions. Their commitment is to deliver high quality services at competitive costs so customers can focus on core business operations.
The document describes a crab sustainability project in Kungkrabaen, Chanthaburi, Thailand. The project aims to conserve the local blue swimmer crab population, which was declining due to overfishing. Key aspects of the project include separating egg-bearing female crabs from others and incubating their eggs, educating local fishermen on sustainable practices, and increasing enforcement of fishing regulations. The project has helped increase crab populations and fishermen's incomes. However, some challenges remain, such as a lack of qualified staff and some locals and tourists still ignoring fishing rules.
The document discusses the history and development of chocolate over centuries. It details how cocoa beans were first used by Mesoamerican cultures before being introduced to Europe where it became popular in powder and liquid forms. Chocolate production methods were refined over the 17th-18th centuries to create chocolate candy, bars, and other familiar products still enjoyed today.
This document provides information on switched mode power supplies (SMPS) and uninterruptible power supplies (UPS). It describes the basic components and functions of power supplies, including transformers, rectifiers, and filters. The document explains that SMPS are more efficient than linear supplies due to switching regulation. It provides block diagrams and discusses advantages like smaller size and higher efficiency. The document also defines UPS as providing backup power during outages. It describes different UPS types and components, including converters, batteries, and inverters. Applications of SMPS and UPS include computers, security systems, industrial equipment, and more.
7. Schultze and Sherif Approximation
เป็นการประมาณโดยใช้สมการที่ 4.4 ซึ่งได้จากกรณีศึกษา 48 กรณี เทียบกับผลการทดสอบ
ทะลวงมาตรฐาน
i
0.87
60(ave)
× f
f ×q× B
D
N 1+0.4
B
(4.4)
0
0
0.01
0.02
0.03
0.04
0.05
0.06
0.07
0.08
0.09
0.10
0.11
0.5 1.0 1.5 2.0
B
Df
H
q
L =100
B 5
2
1
H/B
f
รูปที่ 4.4 ค่าตัวประกอบ f
8. โดย i = ค่าการทรุดตัวทันทีทันใด หน่วยเป็นฟุต
f = ค่าตัวประกอบของอิทธิพลจากรูปร่าง จากรูปที่ 4.4
q = ค่าความดันที่ฐานรากกระทาต่อดินหน่วยเป็นตันต่อตารางฟุต
B = ความยาวของฐานราก หน่วยเป็นฟุต
L = ความกว้างของฐานราก หน่วยเป็นฟุต
Df = ความลึกของฐานรากจากผิวดิน หน่วยเป็นฟุต
H = ความลึกจากใต้ฐานรากลงไปถึงชั้นดินแข็ง หน่วยเป็นฟุต
N60(avg) = ค่าเฉลี่ยของ N60 ตลอดความหนา H
Modified Terzaghi and Peck Approximation
เป็นการปรับปรุงการศึกษาที่เกี่ยวข้องกับความดันที่กดทับและน้าใต้ดินของเทอซากิและเป๊ก
โดยการปรับค่า SPT-N ให้เป็น N’ ดังสมการที่ 4.5
N60’ = N60Cw CN (4.5)
w
w
f
C = 0.5+0.5× D
D +B
(4.6)
โดย CN = ค่าปรับแก้เนื่องจากความเค้นประสิทธิผลให้เทียบเท่า 1 ตันต่อตารางฟุตโดยใช้
กราฟในรูปที่ 4.5
Dw = ความลึกจากระดับฐานรากลงไปถึงระดับน้าใต้ดิน
Cw จะมีค่าเป็น 0.5 ถ้าระดับน้าใต้ดินอยู่ที่ผิวดิน และมีค่าเป็น 1 ถ้าเป็นทรายแห้งหรือระดับ
น้าใต้ดินอยู่ลึกกว่า Df + B ใต้ผิวดิน
ค่าการทรุดตัวเป็นดังสมการที่ 4.7
i
1
q
18 q (4.7)
โดย i = ค่าการทรุดตัวทันทีทันใด หน่วยเป็นฟุต
q = ค่าความดันที่ฐานรากกระทาต่อดินหน่วยเป็นตันต่อตารางฟุต
q1 = ความดันของดินจากกราฟในรูปที่ 4.6
13. ในกรณีที่มีข้อมูล N60 สามารถประมาณค่า qc ได้โดยใช้อัตราส่วนที่แสดงในตารางที่ 4.4
และอาจตรวจสอบความน่าเชื่อถือของค่าต่างๆ กับตารางที่ 4.5
ตัวอย่างที่ 4.1 ฐานรากสี่เหลี่ยมจัตุรัสรับน้าหนักบรรทุกในชั้นดินดังแสดงในรูปที่ 4.8 ให้หาค่าการ
ทรุดตัวหลังจากถูกความดันกระทาเป็นเวลา 10 ปี
การคานวณค่าการทรุดตัวโดยวิธีของ Schmertmann นี้ อาจทาเป็นแผ่นงาน (Work Sheet)
ได้ดังแสดงในรูปที่ 4.8
B = 10 ft
' = 0.06 tcf
Df = 3.00 ft '0 = 0.18 tsf
q = 2.00 tsf
2.0 ft
Z 1.82 tsf
Time = 10 year
C1 = 0.95
Ct = 1.40
'Izp = 0.48 tsf
Izp = 0.69
ft
0.014
Es,
tsf
Iza/Es
0 0.0 0.10
Z,
ft
Z/B Iz Iza
Z = 0.2B =
0.22 175 0.0013
p = q - '0 =
2 0.2 0.34
0.46 175 0.0026
4 0.4 0.58
0.61 175 0.0035
6 0.6 0.65
i = C1C2 p Z Sum = 0.0664
8 0.8
Sum Iza/Es=
0.60 175 0.0034
0.56
0.51 175 0.0029
10 1.0 0.46
ความหนา
ของแต่ละชั้น
เท่ากับ 0.2 B
รูปที่ 4.8 ตัวอย่างแผ่นงานสาหรับคานวณค่าการทรุดตัวของดินที่ไม่มีแรงยึดเหนี่ยว
โดยวิธีของ Schmertmann
14. ที่ Z/B เป็น 0 และ 2 ค่า Iz เป็น 0.1 และ 0 ตามลาดับ จากสมการที่ 4.11 และ 4.12 ที่ Z/B
เป็น 0.5 ได้ค่า Izp เป็น 0.69 หลังจากหาค่า Iz ที่ทุกๆ ความลึก 0.2B แล้ว จึงหาค่า Iza ซึ่งเป็น
ค่าเฉลี่ยของดินแต่ละชั้นซึ่งหนา 0.2B
Burland and Burbidge Approximation
วิธีนี้พัฒนามาจากการศึกษาผลของ SPT เทียบกับค่าการทรุดตัวประมาณ 200 แห่ง ได้เป็น
สมการที่ 4.16 ถึง 4.20
' '
p i avg
' ' 0.7
avg s i p c P : = f f P - B I
2
3
(4.16)
'
p i
' ' c
avg s i avg
I
P : = f f P
3
(4.17)
s
2
f =
+0.25
L
1.25
B
L
B
(4.18)
i
1 1
H
f =
Z
H
2 -
Z
(4.19)
P’avg = qavg+’ avg (4.20)
โดย i = ค่าการทรุดตัวทันทีทันใด หน่วยเป็นฟุต
’p = ความเค้นประสิทธิผลสูงสุดที่กระทาต่อดินในอดีต หน่วยเป็นตันต่อตารางฟุต
Ic = ค่าตัวประกอบของอิทธิพลของการอัดตัว (Compressibility Influence Factor)
1.4
60avg
0.23
N
15. B = ความกว้างของฐานราก หน่วยเป็นฟุต
L = ความยาวของฐานราก หน่วยเป็นฟุต
H = ความหนาของชั้นดิน หน่วยเป็นฟุต
Z1 = ความลึกของอิทธิพลของพื้นที่ที่น้าหนักกระทา (Depth of Influence of Loaded
Area) หน่วยเป็นฟุต ค่านี้หมายถึงความลึกในช่วงใต้ฐานรากลงไปที่มีการทรุด
ตัว 25 เปอร์เซ็นต์ของการทรุดตัวที่ใต้ฐานราก มีค่าโดยประมาณเป็น 1.35B0.75
ถ้าค่า N60avg เพิ่มขึ้นหรือคงที่ตามความลึก และมีค่าโดยประมาณเป็น 2B ถ้า
ค่า N60avg ลดลงอย่างสม่าเสมอตามความลึก
N60avg = ค่าเฉลี่ยของ N60avg ตลอดความลึก Z1 ค่านี้ ไม่ต้องปรับแก้เนื่องจากความเค้น
ประสิทธิผล แต่ต้องปรับแก้หากดินนั้นอยู่ใต้ระดับน้า โดยปรับแก้เป็น N60avg +
0.5(N60avg-15) ในกรณีที่เป็นทรายละเอียดหรือทรายปนตะกอนทราย และ
ปรับแก้เป็น 1.25 N60avg สาหรับกรวดหรือกรวดปนทราย
qavg = ค่าเฉลี่ยของความดันที่ฐานรากกระทาในชั้นดินหนา H
’ avg = ค่าเฉลี่ยของความดันที่ฐานรากกระทาในชั้นดินหนา H
ค่าการทรุดตัวที่คานวณได้โดยสมการที่ 4.16 และ 4.17 นี้ จะมีความแม่นยาเมื่อค่า เป็นดัง
สมการที่ 4.21
1.3 1.67 avg c avg
0.08 I 1.37
N N (4.21)
วิธีนี้สามารถใช้ประมาณค่าการทรุดตัวที่มากกว่า 3 ปีเนื่องจากการล้าและการอัดตัวระยะที่
สองได้ดังนี้
t = fti (4.22)
t 3 t
t
f =1+R +R log
3
(4.23)
โดย t = ค่าการทรุดตัวเมื่อเวลาผ่านไปอย่างน้อย 3 ปีหลังจากก่อสร้างเสร็จ หน่วยเป็น
ฟุต