This document provides the structural design for a frozen ground wall to support shaft sinking at the Khalashpir coal field in Bangladesh. Key aspects of the design include:
- The frozen wall will be cylindrical with a thickness of 1.5m and surround a shaft with a radius of 3.9m.
- 36 freezing boreholes will be arranged in a circle around the shaft with 1.2m spacing to create the frozen wall. The boreholes will extend 162m vertically.
- Calculations are shown to determine the overburden pressure, ice wall thickness, borehole arrangement diameter, and number of boreholes based on site conditions and established formulas.
- Stresses on the ice wall
OPTIMUM DESIGN FOR HIGHWAY EMBANKMENT WITH STONE COLUMNIAEME Publication
In this paper discusses how to design the highway embankment with an optimum process to
get a minimum area of the highway embankment to reduce the cost of construction, and the
problems of soft clay soil in southern of Iraq when construction highway embankment as low
bearing capacity and excessive settlement and the way to treat it.At beginning a model of the
high way embankment without improving of soft clay soil for height of highway embankments
(H=2m and H=3m) was built to note the problems which will be faced when construction of
highway embankment in the future. When the height of embankment is (H=2m) the excessive
settlement appears but when the height of embankment is (H=3m) the low bearing capacity as
well as the excessive settlement will appear. To avoid these problems, the soft clay soil will be
improved by using stone columns and design the stone columns also with optimum process to
get minimum area of stone columns that can carry the applied load without any problem like
low bearing capacity or excessive settlement with lowest cost. When the stone columns are
used to improve the soft clay soil, it can note reduce in settlement by (99%) for height of
highway embankment (H=2m), and increase in bearing capacity to (15%) for height of
highway embankment (H=3m) for certain diameter as minimum increase can carry the load
applied on foundation. The highway embankment with stone column modeling with ANSYS
software program and this program very useful to help to find optimum design by optimization
tool, and use geo slope program to find slope stability for highway embankment by Bishop’s
method.
OPTIMUM DESIGN FOR HIGHWAY EMBANKMENT WITH STONE COLUMNIAEME Publication
In this paper discusses how to design the highway embankment with an optimum process to
get a minimum area of the highway embankment to reduce the cost of construction, and the
problems of soft clay soil in southern of Iraq when construction highway embankment as low
bearing capacity and excessive settlement and the way to treat it.At beginning a model of the
high way embankment without improving of soft clay soil for height of highway embankments
(H=2m and H=3m) was built to note the problems which will be faced when construction of
highway embankment in the future. When the height of embankment is (H=2m) the excessive
settlement appears but when the height of embankment is (H=3m) the low bearing capacity as
well as the excessive settlement will appear. To avoid these problems, the soft clay soil will be
improved by using stone columns and design the stone columns also with optimum process to
get minimum area of stone columns that can carry the applied load without any problem like
low bearing capacity or excessive settlement with lowest cost. When the stone columns are
used to improve the soft clay soil, it can note reduce in settlement by (99%) for height of
highway embankment (H=2m), and increase in bearing capacity to (15%) for height of
highway embankment (H=3m) for certain diameter as minimum increase can carry the load
applied on foundation. The highway embankment with stone column modeling with ANSYS
software program and this program very useful to help to find optimum design by optimization
tool, and use geo slope program to find slope stability for highway embankment by Bishop’s
method.
Gas foil bearing analysis and the effect of bump foil thickness on its perfor...ijmech
Gas foil bearings (GFBs) satisfy many of the requirements noted for novel oil-free turbomachinery.However, GFBs have a limited load carrying capacity. This paper presents a numerical model in order to assess the performance characteristics of gas foil bearings. The finite difference scheme has been used to discretize the governing Reynolds equation and the pressure is calculated by solving non-linear matrix equation using Newton-Raphson technique. The static performance analysis has been carried out. The computational analysis have been compared with the experimental and theoretical results available in the literature and the effects of bump foil thickness, number of bumps and bump compliance coefficient on the load carrying capacity at different rotor speed have been investigated. The results of the study show that too thin bump foil thickness may lead to a significant decrease in the load capacity. However for accurate predictions of the foil bearing performances, more details foil structure of 1D and 2D finite element model
should be considered.
Performance of cyclic loading on circular footing on geogrid reinforced sandbedeSAT Journals
Abstract Foundation is a part of structure which transmits weight of structure to the ground. In addition to static loads the foundations are subjected to dynamic loads like machine loads, seismic loads and moving wheel loads. This paper presents laboratory test results of cyclic loading on circular footing on geogrid reinforced sandbed for different densities. In this paper, works are carried out on circular footing with different densities i.e. 1.642gm/cc, 1.722gm/cc, 1.763gm/cc and with number of layers as 0, 1, 2, 3. Dynamic soil properties as coefficient of elastic uniform compression Cu, coefficient of elastic uniform shear Cτ, coefficient of elastic non-uniform shear Cψ and the coefficient of elastic non uniform compression Cφ were also determined. It has been concluded that as density of sand bed and as number of layers increases, settlement of footing decreases. Keywords : Cyclic loading, geogrid, coefficient of elastic uniform compression , coefficient of elastic uniform shear, coefficient of elastic non-uniform shear and the coefficient of elastic non uniform compression.
EXPERIMENTAL STUDY ON COIR FIBRE REINFORCED FLY ASH BASED GEOPOLYMER CONCRETE...IAEME Publication
Background/Objectives: By using the fly residue as option substance to bond in concrete it reduces the usage of normal Portland cement in usual concrete which results in the development of Geopolymer concrete furthermore in the lessening of CO2 levels which thusly reduces the Global Warming. Methods/Statistical analysis: This paper presents the trial examination done on the execution of coir fibre reinforced fly residue based geopolymer concrete subjected to severe ecological conditions. The mixes were considered for molarity of 10M. The basic arrangement utilized for present revise is the blend of sodium silicate and sodium hydroxide arrangement with the proportion of 1:2.5. Coir fibre with the varying percentages of 0, 0.75, 1.5, 2.25 and 3 are used as fibre reinforcement. The test specimens of 150mmx150mmx150mm cubes, 150mmx300mm cylinders, 1000mmx150mmx150mm beams are cast and cured under encompassing temperature conditions. Findings: The geopolymer solid examples are tried for their compressive quality, flexural and split tractable tests at 7days, 14days and 28days.The test grades demonstrate that the blend of fly ash and coir fibre can be used for the improvement of geopolymer concrete. Applications: It possesses superior distinctiveness such as high strength, very little drying shrinkage , low creep, durable nature, eco-friendly, fire proof ,better compressive strength etc to be used as an alternative of OPC
Fixity depth of offshore piles in elastoplastic soft clay under dynamic loadeSAT Journals
Abstract
This work represents study of dynamic behavior of offshore piles embedded in elastoplastic soft clay, and estimating the fixity depth of pile. ABAQUS finite element program which used to simulate the problem. The soil was modeled in two case elastic state model and elastoplastic state model represented by cam-clay model, three dimension element used to represent the interaction between pile and soil, and laboratory tests used to getting the real properties of clayey soil and to descried interface. The results obtained developed two empirical equations used to calculate depth of pile fixity for pile embedded in elastic and elastoplastic soil respectively. Also, show the depth of pile fixity is increase about (40 %) due to change soil model from elastic to plastic, when pile embedded in elastoplastic soil its dependent on soil strength, interface properties and pile rigidity. The pile head displacement is increase about 90 % while the bending moment is decease 10 % at pile head.
DYNAMIC RESPONSE OF CONCRETE GRAVITY DAM ON RANDOM SOILIAEME Publication
This research reports the dynamic response of a concrete gravity dam under seismic excitation including dam‒reservoir‒foundation interaction. A peek ground accelerations PGAS of 0.6ghas been applied on a numerical model of the gravity dam that is built by finite element method using ANSYS. In this model, the dam is considered as a rigid body, the reservoir as compressible in viscid fluid, and the foundation as a random soil. A parametric study is achieved through change of relative density (Dr) of ground soil, namely, Dr= 60% and 80%. Modal and transient analyses have been considered to achieve the results. The results are analyzed and compared with experimental ones. It is shown a significant variation in the estimated seismic response when the interaction is included in analyses.
Effect of fines on liquefaction using shake table testeSAT Journals
calamities resulting into considerable damages. One of the most detrimental
effects caused due to earthquake is liquefaction. This paper deals with experimental investigation of effects of fines content on
liquefaction behavior using shake table test. A test program consisted of total 19 tests conducted on saturated cohesionless sand
with varying amount of non-plastic silt. The behavior of such silty sand in the relative density range 30 to 60% has been studied
by subjecting the specimens to a specific acceleration of 0.54g. Effect of silt content and the relative density on generation of pore
pressure and thereby initiation of liquefaction has been studied. The results obtained from the present study showed that cyclic
stress ratio (CSR) values decrease with the increase in fines content for lower relative densities. Delay in development of pore
pressure is observed with the increasing fines content. This indicates that higher silt contents at higher densities offer better
resistance to liquefaction. Further, for lower densities and lesser silt contents liquefaction occurred at pore pressure ratio even
less than one. The trend observed for CSR and relative density is similar when compared with triaxial test reported in literature.
The points where liquefaction has occurred in the field, when checked in the present study, they lie in ‘YES’ zone of liquefaction.
Keywords: Relative Density, Cyclic Stress Ratio, Pore Pressure Ratio, Liquefaction Resistance, Initiation of
Liquefaction
Effect of soft storeys in earthquake resistant analysis of rc framed structureseSAT Journals
storey in which the stiffness is less than 70% of the storey above or less
than 80% of the combined stiffnesses of the three storeys above. It is the general practice in the multistoreyed buildings to
accommodate parking facilities for the vehicles of the occupants of the building. As we know that the soft storey in a building
structure causes stiffness irregularity in a structure, due to this the structure undergoes unequal storey drifts, formation of the
plastic hinges and then finally resulting into the collapse of the structure.This research work purely interacts with the effect of the
soft storeys in the analysis of RC framed structures as entitled above, and in this work the soft storeys positions has been provided
at different levels as shown in the analytical modelling. All the models are analyzed by using the ETABS software. The seismic
analysis performed consists of the Equivalent static analysis (ESA), response spectrum analysis (RSA), and the push over analysis
(PA). The seismic base shear forces, storey drifts, and the displacements has been compared with the three analysis methods as
listed above. With the aid of the push over analysis the values of the ductility and the response reduction factor have been
obtained. Apart from these, the performance point parameters such as spectral acceleration(Sa) , spectral displacement (Sd),
Base shear(V) and the roof displacement(D) has been also illustrated in this work and a detailed information of several stages of
the hinge formation (A,B,IO,LS,CP,C,D,E) has also been illustrated.. Keywords: Soft Storey, Stiffness, Storey Drift, Storey Displacement, Earthquake, RC Frames
IJRET : International Journal of Research in Engineering and Technology is an international peer reviewed, online journal published by eSAT Publishing House for the enhancement of research in various disciplines of Engineering and Technology. The aim and scope of the journal is to provide an academic medium and an important reference for the advancement and dissemination of research results that support high-level learning, teaching and research in the fields of Engineering and Technology. We bring together Scientists, Academician, Field Engineers, Scholars and Students of related fields of Engineering and Technology
Implementation of finite volume method in creeping flow around a circular cyl...eSAT Journals
Abstract
A Finite Volume Method have been performed in simulation of creeping flow around a circular cylinder contained between plates. By adopting the SIMPLE algorithm the governing equations are solved together with Papanastasious regularization. Apparent viscosity is calculated on each iteration by using forward difference operation. Yield surfaces are studied over the range of Oldroyd number 10≤Od≤〖10〗^4. The model results are found to be in good agreement with obtained results of the other method.
Keywords: Creeping flow, Finite Volume Method, Yielded and unyielded zone, Bingham number.
Driven Customer Service & Sale Professional with extensive strategic sales & Marketing experience. Comprehensive background across all aspects of customer engagement, customer retention, customer service, customer care, & customer satisfaction. Proficiency in staff recruitment, development and training, with ability to lead and motivate others to achieve business success. Excellent communicator,.
Gas foil bearing analysis and the effect of bump foil thickness on its perfor...ijmech
Gas foil bearings (GFBs) satisfy many of the requirements noted for novel oil-free turbomachinery.However, GFBs have a limited load carrying capacity. This paper presents a numerical model in order to assess the performance characteristics of gas foil bearings. The finite difference scheme has been used to discretize the governing Reynolds equation and the pressure is calculated by solving non-linear matrix equation using Newton-Raphson technique. The static performance analysis has been carried out. The computational analysis have been compared with the experimental and theoretical results available in the literature and the effects of bump foil thickness, number of bumps and bump compliance coefficient on the load carrying capacity at different rotor speed have been investigated. The results of the study show that too thin bump foil thickness may lead to a significant decrease in the load capacity. However for accurate predictions of the foil bearing performances, more details foil structure of 1D and 2D finite element model
should be considered.
Performance of cyclic loading on circular footing on geogrid reinforced sandbedeSAT Journals
Abstract Foundation is a part of structure which transmits weight of structure to the ground. In addition to static loads the foundations are subjected to dynamic loads like machine loads, seismic loads and moving wheel loads. This paper presents laboratory test results of cyclic loading on circular footing on geogrid reinforced sandbed for different densities. In this paper, works are carried out on circular footing with different densities i.e. 1.642gm/cc, 1.722gm/cc, 1.763gm/cc and with number of layers as 0, 1, 2, 3. Dynamic soil properties as coefficient of elastic uniform compression Cu, coefficient of elastic uniform shear Cτ, coefficient of elastic non-uniform shear Cψ and the coefficient of elastic non uniform compression Cφ were also determined. It has been concluded that as density of sand bed and as number of layers increases, settlement of footing decreases. Keywords : Cyclic loading, geogrid, coefficient of elastic uniform compression , coefficient of elastic uniform shear, coefficient of elastic non-uniform shear and the coefficient of elastic non uniform compression.
EXPERIMENTAL STUDY ON COIR FIBRE REINFORCED FLY ASH BASED GEOPOLYMER CONCRETE...IAEME Publication
Background/Objectives: By using the fly residue as option substance to bond in concrete it reduces the usage of normal Portland cement in usual concrete which results in the development of Geopolymer concrete furthermore in the lessening of CO2 levels which thusly reduces the Global Warming. Methods/Statistical analysis: This paper presents the trial examination done on the execution of coir fibre reinforced fly residue based geopolymer concrete subjected to severe ecological conditions. The mixes were considered for molarity of 10M. The basic arrangement utilized for present revise is the blend of sodium silicate and sodium hydroxide arrangement with the proportion of 1:2.5. Coir fibre with the varying percentages of 0, 0.75, 1.5, 2.25 and 3 are used as fibre reinforcement. The test specimens of 150mmx150mmx150mm cubes, 150mmx300mm cylinders, 1000mmx150mmx150mm beams are cast and cured under encompassing temperature conditions. Findings: The geopolymer solid examples are tried for their compressive quality, flexural and split tractable tests at 7days, 14days and 28days.The test grades demonstrate that the blend of fly ash and coir fibre can be used for the improvement of geopolymer concrete. Applications: It possesses superior distinctiveness such as high strength, very little drying shrinkage , low creep, durable nature, eco-friendly, fire proof ,better compressive strength etc to be used as an alternative of OPC
Fixity depth of offshore piles in elastoplastic soft clay under dynamic loadeSAT Journals
Abstract
This work represents study of dynamic behavior of offshore piles embedded in elastoplastic soft clay, and estimating the fixity depth of pile. ABAQUS finite element program which used to simulate the problem. The soil was modeled in two case elastic state model and elastoplastic state model represented by cam-clay model, three dimension element used to represent the interaction between pile and soil, and laboratory tests used to getting the real properties of clayey soil and to descried interface. The results obtained developed two empirical equations used to calculate depth of pile fixity for pile embedded in elastic and elastoplastic soil respectively. Also, show the depth of pile fixity is increase about (40 %) due to change soil model from elastic to plastic, when pile embedded in elastoplastic soil its dependent on soil strength, interface properties and pile rigidity. The pile head displacement is increase about 90 % while the bending moment is decease 10 % at pile head.
DYNAMIC RESPONSE OF CONCRETE GRAVITY DAM ON RANDOM SOILIAEME Publication
This research reports the dynamic response of a concrete gravity dam under seismic excitation including dam‒reservoir‒foundation interaction. A peek ground accelerations PGAS of 0.6ghas been applied on a numerical model of the gravity dam that is built by finite element method using ANSYS. In this model, the dam is considered as a rigid body, the reservoir as compressible in viscid fluid, and the foundation as a random soil. A parametric study is achieved through change of relative density (Dr) of ground soil, namely, Dr= 60% and 80%. Modal and transient analyses have been considered to achieve the results. The results are analyzed and compared with experimental ones. It is shown a significant variation in the estimated seismic response when the interaction is included in analyses.
Effect of fines on liquefaction using shake table testeSAT Journals
calamities resulting into considerable damages. One of the most detrimental
effects caused due to earthquake is liquefaction. This paper deals with experimental investigation of effects of fines content on
liquefaction behavior using shake table test. A test program consisted of total 19 tests conducted on saturated cohesionless sand
with varying amount of non-plastic silt. The behavior of such silty sand in the relative density range 30 to 60% has been studied
by subjecting the specimens to a specific acceleration of 0.54g. Effect of silt content and the relative density on generation of pore
pressure and thereby initiation of liquefaction has been studied. The results obtained from the present study showed that cyclic
stress ratio (CSR) values decrease with the increase in fines content for lower relative densities. Delay in development of pore
pressure is observed with the increasing fines content. This indicates that higher silt contents at higher densities offer better
resistance to liquefaction. Further, for lower densities and lesser silt contents liquefaction occurred at pore pressure ratio even
less than one. The trend observed for CSR and relative density is similar when compared with triaxial test reported in literature.
The points where liquefaction has occurred in the field, when checked in the present study, they lie in ‘YES’ zone of liquefaction.
Keywords: Relative Density, Cyclic Stress Ratio, Pore Pressure Ratio, Liquefaction Resistance, Initiation of
Liquefaction
Effect of soft storeys in earthquake resistant analysis of rc framed structureseSAT Journals
storey in which the stiffness is less than 70% of the storey above or less
than 80% of the combined stiffnesses of the three storeys above. It is the general practice in the multistoreyed buildings to
accommodate parking facilities for the vehicles of the occupants of the building. As we know that the soft storey in a building
structure causes stiffness irregularity in a structure, due to this the structure undergoes unequal storey drifts, formation of the
plastic hinges and then finally resulting into the collapse of the structure.This research work purely interacts with the effect of the
soft storeys in the analysis of RC framed structures as entitled above, and in this work the soft storeys positions has been provided
at different levels as shown in the analytical modelling. All the models are analyzed by using the ETABS software. The seismic
analysis performed consists of the Equivalent static analysis (ESA), response spectrum analysis (RSA), and the push over analysis
(PA). The seismic base shear forces, storey drifts, and the displacements has been compared with the three analysis methods as
listed above. With the aid of the push over analysis the values of the ductility and the response reduction factor have been
obtained. Apart from these, the performance point parameters such as spectral acceleration(Sa) , spectral displacement (Sd),
Base shear(V) and the roof displacement(D) has been also illustrated in this work and a detailed information of several stages of
the hinge formation (A,B,IO,LS,CP,C,D,E) has also been illustrated.. Keywords: Soft Storey, Stiffness, Storey Drift, Storey Displacement, Earthquake, RC Frames
IJRET : International Journal of Research in Engineering and Technology is an international peer reviewed, online journal published by eSAT Publishing House for the enhancement of research in various disciplines of Engineering and Technology. The aim and scope of the journal is to provide an academic medium and an important reference for the advancement and dissemination of research results that support high-level learning, teaching and research in the fields of Engineering and Technology. We bring together Scientists, Academician, Field Engineers, Scholars and Students of related fields of Engineering and Technology
Implementation of finite volume method in creeping flow around a circular cyl...eSAT Journals
Abstract
A Finite Volume Method have been performed in simulation of creeping flow around a circular cylinder contained between plates. By adopting the SIMPLE algorithm the governing equations are solved together with Papanastasious regularization. Apparent viscosity is calculated on each iteration by using forward difference operation. Yield surfaces are studied over the range of Oldroyd number 10≤Od≤〖10〗^4. The model results are found to be in good agreement with obtained results of the other method.
Keywords: Creeping flow, Finite Volume Method, Yielded and unyielded zone, Bingham number.
Driven Customer Service & Sale Professional with extensive strategic sales & Marketing experience. Comprehensive background across all aspects of customer engagement, customer retention, customer service, customer care, & customer satisfaction. Proficiency in staff recruitment, development and training, with ability to lead and motivate others to achieve business success. Excellent communicator,.
IJRET : International Journal of Research in Engineering and Technology is an international peer reviewed, online journal published by eSAT Publishing House for the enhancement of research in various disciplines of Engineering and Technology. The aim and scope of the journal is to provide an academic medium and an important reference for the advancement and dissemination of research results that support high-level learning, teaching and research in the fields of Engineering and Technology. We bring together Scientists, Academician, Field Engineers, Scholars and Students of related fields of Engineering and Technology
Statistical analysis of various sub systems of panel production system in und...eSAT Journals
Abstract System Analysis Approach has been applied in the present field based research paper for a deep and gassy coal mine of Jharia coal fields. The working panel was considered as a System, splitted into various sub-Systems. The Sub-Systems were statistically analyzed in terms of frequency distribution (after prolonged field observations). The Mean, Median, Mode, Standard deviation, Variance and co-efficient of variation were calculated. Among the Mean, Median and Mode, Mean was considered for Capacity (in terms of production) calculation of various Sub-systems
Structural Design and Rehabilitation of Reinforced Concrete StructureIJERA Editor
Effective rehabilitation scheme for failed structure demands methodical analysis of various
causes of failure and intended service loads and other functional details, The actual study under deliberation is
the best example of rehabilitation Structural element – Basement RCC raft, failed to sustain uplift due to ground
water table. This paper dealt with the rehabilitation of basement RCC raft foundation considering various design
aspects like uplift due to ground water table, sub-soil properties and restriction on depth of raft to suffice
available headroom for intended use.
Surface or shallow compaction is one of the earliest, cheapest and commonly used techniques to improve the physical and
mechanical properties of loose soil specially for imported structural fill. It is simply rearranging of soil particles to reduce air ratios using
surface static or vibrating mechanical effort. Usually, shallow compaction procedure includes subjecting the loose soil to certain number of
compacting equipment passes to archive the accepted compaction level; this number of passes is a function of many parameters such as
type of soil, initial soil parameters, compacting equipment characteristics and thickness of soil lift. International codes, specifications and
handbooks include just guidelines about the required number of passes; accordingly, it is usually determined based on personal
experience and field trials. This research has two goals, the first is to estimate the properties improvement of certain natural surface loose
soil under certain surface compaction procedure by calculating the enhancement in soil properties after each pass and updating the soil
properties for next pass calculations. The second goal is to use the previous approach to develop set of equations to design surface
compaction procedure for imported structural fill, this includes calculating minimum compaction equipment characteristics, maximum lift
thickness and minimum number of passes to enhance certain imported fill from certain initial condition to certain final condition. The
proposed approach for the first goal was verified using case studies and showed good matches, and the developed designing equations for
surface compaction procedure were verified using case studies and showed good matches.
The Geotechnical Properties of Jamshoro Soil (Shale) With CementIJMREMJournal
The geology of Jamshoro soil is nearly consist of multilayers in alternative form. The alternative layer of Jamshoro soil occur in the form of lime stone and shale or vice versa. The basic aim of this research is to improve the geotechnical properties of Jamshoro soil (shale) by using the cement as the stabilized material. This paper reports the effect of cement on the geotechnical characteristic of the cohesive soil and swelling potential of the Jamshoro soil. The soil sample used for testing purpose are thoroughly mixed to obtain the homogeneity. After that thoroughly mixed was dried in the oven. Oven dried sample was mixed with cement at different proportion that was 5% ,10%, 15% and 20% by the soil weight. Water content used in the mixture to form the specimens at optimum moisture contents of the soil. The compacted this prepared soil specimen was done by followed the procedure of standard proctor test. Compacted specimens were cured for the period of 1, 7, 14 and 28 days. After the completion of curing duration of specimen direct shear test was done. On the base of experimental result, it was concluded that the cement showed an appreciable improvement of the cohesion with the curing period.
The Geotechnical Properties of Jamshoro Soil (Shale) With CementIJMREMJournal
The geology of Jamshoro soil is nearly consist of multilayers in alternative form. The alternative layer of
Jamshoro soil occur in the form of lime stone and shale or vice versa. The basic aim of this research is to improve
the geotechnical properties of Jamshoro soil (shale) by using the cement as the stabilized material. This paper
reports the effect of cement on the geotechnical characteristic of the cohesive soil and swelling potential of the
Jamshoro soil. The soil sample used for testing purpose are thoroughly mixed to obtain the homogeneity. After
that thoroughly mixed was dried in the oven. Oven dried sample was mixed with cement at different proportion
that was 5% ,10%, 15% and 20% by the soil weight. Water content used in the mixture to form the specimens at
optimum moisture contents of the soil. The compacted this prepared soil specimen was done by followed the
procedure of standard proctor test. Compacted specimens were cured for the period of 1, 7, 14 and 28 days. After
the completion of curing duration of specimen direct shear test was done. On the base of experimental result, it
was concluded that the cement showed an appreciable improvement of the cohesion with the curing period.
Stabilization of Marine Clays with Geotextile Reinforced Stone Columns Using ...ijceronline
Various techniques are used for improving in-situ ground conditions among which reinforcing the ground with stone column is one of the most versatile and cost effective technique. The presence of stone column on composite ground will impart lower compressibility and higher shear strength than that of native soil. Stone columns are used to improve the poor ground like soft marine clays, cohesive soils, silty soils, loose sand etc. This is the most popular technique used in flexible structures like road embankments, railway embankments and oil storage tanks. In the present study, the floating stone columns were reinforced by introducing lateral circular discs of geo-textile sheets within the column. Silica-Manganese slag which is a byproduct from ferro-alloy industries is used as the stone column material. The circular discs were placed at two different spacing (D and D/2) over varied reinforcement depths (0.25L, 0.5L, 0.75L and L). Laboratory tests have been performed on clay bed, ordinary floating stone column and reinforced stone columns to evaluate the improvement of load carrying capacity. After performing laboratory tests, the test results indicate that load carrying capacities of the stone columns reinforced with circular discs placed at D/2 spacing shows better performance than D spacing.
IJRET : International Journal of Research in Engineering and Technology is an international peer reviewed, online journal published by eSAT Publishing House for the enhancement of research in various disciplines of Engineering and Technology. The aim and scope of the journal is to provide an academic medium and an important reference for the advancement and dissemination of research results that support high-level learning, teaching and research in the fields of Engineering and Technology. We bring together Scientists, Academician, Field Engineers, Scholars and Students of related fields of Engineering and Technology
1. The International Journal of Engineering And Science (IJES)
||Volume||2 ||Issue|| 3 ||Pages|| 69-74 ||2013||
ISSN: 2319 – 1813 ISBN: 2319 – 1805
www.theijes.com The IJES Page 69
Structural Design of Frozen Ground Works For Shaft Sinking By
Practicing Artificial Ground Freezing (Agf) Method in
Khalashpir Coal Field
1,
Atikul Haque Farazi 2,
Chowdhury Quamruzzaman
1,
Environmental and Geospatial Solutions, Coordinator (Geophysical and Environmental
Management Unit)
2,
Associate Professor, Department of Geology, University of Dhaka, Dhaka-1000, Bangladesh
-----------------------------------------------------Abstract---------------------------------------------------------
Khalashpir coal field, the 3rd
largest coal field of Bangladesh where proved reserve of about 143 million tons
and probable reserve of about 685 million tons is estimated, has been decided for underground mining and
artificial ground freezing (AGF) technique has been proposed as shaft sinking method after feasibility study.
This method has been used in mining industry over the past 125 years for support of shaft sinking, tunneling and
foundation excavation. To run the process brine solution is chilled between -25o
C and -35o
C in large refrigerant
plant. The brine is then circulated through freezing tubes in required pattern to remove hit from the ground and
thus freeze the soil to achieve soil strength and decrease the mobility of liquid water. This process results in a
frozen earth barrier which gives strength to loose soil and bars water from inrushing excavation work for
sinking a shaft. In this paper structural design of frozen ground works has been proposed to achieve a vertical
cylindrical ice-wall for shaft sinking in Khalashpir coal field.
Key Words: shaft sinking, ice-wall, structural design, ice-wall thickness, freezing borehole.
---------------------------------------------------------------------------------------------------------------------------------------
Date Of Submission: 01, Feb, 2013 Date Of Publication: 15 March2013
--------------------------------------------------------------------------------------------------------------------------------------
I. Introduction
Constructional work below ground level is normally preceded by a ground investigation to establish the
data sequence, soil/rock properties and hydrogeology of the site. Such exploration must be sufficiently deep and
comprehensive to establish the long-term stability of the intended structure, and of any temporary works needed
to effect the excavation within which the sub-surface permanent works can safely be constructed. The results of
such investigations will identify the location and extent of weak and/or saturated strata, alert the designer to
potential problems or difficulties, and indicate the need for preventive measures. The same data will enable a
ground freezing engineering to prepare a scheme, but supplementary information may be needed before the
design can be finalized. Site investigation boring is needed to know the lithology of the site and for collecting
samples to know the geotechnical properties of the rocks to be frozen in laboratory. Moreover, pumping test
should have to be done to get the hydrogeological condition of the area as ― porosity, permeability, flow
direction, flow rate, hydraulic gradient, volume of water etc. of the water bearing strata. Khalashpir coal field
situated in the Rangpur Saddle of Bangladesh which again belongs to a half graben structure, has four
stratigraphic units from top to bottom:
1. Barind Clay Formation (6m)
2. Dupitila Sandstone Formation (142.50m)
3. Jamalganj Formation (Surma Group equivalent, 184m)
4. Gondwana Formation (814m has been drilled)
[China Jinan Mining Development Corporation (2006) Techno-economic Feasibility Study of Khalaspir Coal
Mine Project, Dhaka, Bangladesh (unpublished)] According to the pumping test and geotechnical data of
borehole GTB-1 drilled in the proposed shaft location, structural design of the frozen wall has been proposed in
this paper. As loose, friable and water bearing Dupitila Formation is the most vulnerable in sense of strength and
water encroachment with unit inflow rate of 661.33 M3
/ day/ M and filtration coefficient 34.67 m/day, the whole
unit has been considered for freezing vertically. [Dr. Yong Om Kil, Khalashpir Coal Mine Project, Pirjang,
Rangpur (2005) Pumping Test Report of Exploration Boreholes on Khalashpir Coal Field (unpublished)].It
2. Structural Design Of Frozen Ground Works…
www.theijes.com The IJES Page 70
should be mentioned that this water bearing, loose, low strength sand dominated formation is the major concern
for the
underground construction, threatened by caving and water ingress. According to this typical problem of shaft
sinking through loose unstable soils (sands, silts and clays), the AGF method that is proved successful and best
suit to serve the purpose in the aforementioned soil condition throughout the world, has been proposed to admit
there for conducting underground works successfully by forming of frozen earth barrier to water and at the same
time increasing compressive strength of soil remarkably. This method is environment friendly, safe, not limited
to typical soil condition and has nearly no effect on water table and water condition.[ Farazi A. H.,
Quamruzzaman C., Ferdous N. Mumin A., Mustahid F., Kabir A. K. M. F., (2012) Selection of Shaft Sinking
Method for Underground Mining in Khalashpir Coal Field, Khalashpir, Rangpur, Bangladesh]Frozen ground
works have been designed for a shaft of 3.9m radius which would be enclosed by a ring shaped freezing wall.
Total vertical length to be frozen has been estimated 162m which includes 6m of Barind Formation, 144.50m of
Dupitila Formation and 12.5m additional freezing for safety of the temporary structure. This paper is
continuation of the previous one proposing AGF method for shaft sinking in the site. Values of the parameters in
the used formulae were taken from the borehole GTB-1 data drilled by Korea South-South Cooperation
Corporation which is situated at the shaft sinking location proposed by China Jinan Mining Development
Corporation (2006). This paper is a continuation of our previous one suggesting AGF method for shaft sinking
in the coal field, based on ground information gathered which is the primary scheme of engineering design
frozen ground works.
II. Structural Design
The design of a successful ‘ice-wall’ for an AGF scheme requires thermal and structural calculation
[Harris J.S. Ground Freezing in Practice, 1995]. After selection ‘structural design’ is the second sequence of
AGF events. It should be kept in mind that excessively thick or too thin ice-wall is not desirable for its cost and
time consumption or breakage. Another important factor for designer is that ice should not encroach into the
excavation area which causes time killing and costing as well. When building the underground construction by
an open-cast method with the freezing method of rock, the ice-wall carries out the function of support wall. The
most common ice-wall configuration is based on the circle since, in the ideal case; this is the only shape which
offers uniform compressive stress and minimal tensile stress in the ice-wall during its working life. Thus circular
constructions are the simplest to design to construct. [Harris J.S. (1995)) Ground Freezing In Practice]. For
Khalashpir coal field circular shaped ice-wall has been proposed and designed accordingly in this paper.
Determination of the thickness of unlined frozen ground barrier according to loads of surrounding ground is the
most important of the design procedure. After this, the diameter of the borehole arrangement circumference and
number of boreholes is calculated. When the necessary geotechnical properties of the ground are known, this
engineering design is nothing but replacing parameters of the formulae by values and calculation.
III. Calculation
Calculation of Overburden Pressure
The thickness of ice-wall is determined in consideration of the shape and size of the shaft, technical
processes of mine construction, rock pressure and static-hydraulic pressure of water. Overburden pressure is an
important parameter of the equation regarding ice-wall thickness. So, it is mandatory to calculate overburden
pressure on frozen wall to designing a sustainable frozen barrier. In soft rock, the rock pressure Pr can be
determined by the following formula.
……………… (1)
= 688.12 KPa.
Where rg = volume weight or density of the formation= 1.99 t/m3
, Q = acceleration of gravity= 10, H is the
height as shown in the Fig. 2 = 162m and Ø = internal frictional angle of the seam= 24o
When deciding rock
pressure in water saturated rock seam below the underground water level , the static hydraulic pressure of water
Ph is determined as the following formula in consideration of the density of water.
……………… (2)
= 760 KPa
Where, rw = density of water= 1t/m3
and h is the head of water= (82-6) m = 76m (from Fig ?? )
The whole load which acts on ice-wall is determined by addition of rock and water pressure. So the overburden
load Po is:
…………… (3)
= 1.448 Mpa
[Sin K.C. & Young J. (1998) Driving and Mining (Kim Chaek University of Technology)]
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IV. Calculation Of Ice-Wall Thickness
The thickness of the ice-wall is one of the main parameters of deciding the economical rationality of
using the freezing method. The excessive or too thin thickness of ice-wall might have enormous volume to be
frozen or breakdown of ice-wall or explosion of underground water. Based on the taken thickness of the
freezing wall, all the heat-engineering and technological calculation of refrigerating processes is realized. To
determine the thickness of the ice-wall is a very complex problem in technological view. This complexity is that
the ice-wall has not got lawfulness of elastic body and has the changing property clearly and its characteristics
depend on the rock type, freezing temperature and time for forming the ice-wall. Besides, depending on the
thickness of the ice-wall, it has the elastic characteristics of different strength and its change law depends on the
law of heat field change in the ice-wall.
The characteristic load and stress patterns are illustrated in Figs 1, 2 and 3 which clarify the formulae used here.
Fig 1 Shaft nomenclature
Fig 2 Load nomenclature (cross section)
Fig 3 Shaft load nomenclature (plan view); where P = Po + P1, P1 = Pl/2(1 +cos2Ø) and Pl = 0.0013H, i.e.
0.13 × hydrostatic pressure from the surface [Link et al (1976)].
[Harris J.S. (1995) Ground Freezing In Practice (Thomas Telford Services Ltd, London]
Many formulae have been developed based on different elasto-palstic properties of ice-wall. The thickness of
frozen support wall t has been determined by the following formula here:
…………… (4)
= 1.5 m
where, q is unconfined compressive strength in frozen state= 4MP (for saturated sand at less then -10o
C), R=
radius of shaft.
Po
UnfrozenFrozen
Elastic
r
ro
s
Plastic
Frozen t
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Fig. 4 Characteristic ice-wall formation pattern led by equation (4), where r is radius of shaft, ro is outer
radius of ice-wall and s =
This formula was, proposed by Shangdong Mining College and others to take account inter alia of plastic
deformation of the ice-wall. Serious creep deformation and basal heave is reported to have occurred at 257m
depth, together with associated freeze tube breakages, suggesting that in this case the design gave a factor of
safety approximating to 1 at that depth. The formula used here is yields thickness is both adequate and generally
less than that which is generated by the usual range of spacing between freeze-tubes.
[Harris J.S. (1995) Ground Freezing In Practice (Thomas Telford Services Ltd, London]
Verticality of freezing boreholes
The drilling of vertical freezing is one of the most difficult and long time processes when freezing rock. The
period drilling boreholes takes 30 ~ 65% of the whole time to be required in freezing the rock according to the
depth of borehole. The Final diameter of borehole should be a little larger than the diameter of the connecting
bushing of the freezing pipe and its diameter should be less than 150 ~ 170mm. When the depth of freezing the
rock is very big (500 ~ 700m), final diameter of the freezing borehole is about 200 ~ 250mm.
The depth of the borehole should be 5 ~ 20m deeper than designed of level of the rock freezing. In the borehole,
the freezing pipe of given diameter should be moved in and out freely. The borehole variation about given
diameter should be minimum. When the depth of shaft reaches 500m level, the maximum variation of borehole
is as follows.
a = 0.5 + 0.002H,m …………… (5)
Where H ― depth of borehole, m.
a=1 has been considered here in calculation here for designing of this shallow structure.
In case the borehole has some variation against vertical direction, its value is compared with the allowable
standard or the borehole should be drilled again. When freezing rock, additional freezing boreholes are drilled
less than 10% of the whole boreholes in case the depth is 100m, and 15% in case of 200m, and 20% in case of
400m. The percussive drilling, rotary drilling and their combination are used in drilling the freezing borehole.[
Sin K.C. & Young J. (1998) Driving and Mining (Kim Chaek University of Technology)].
V. Calculation For Freezing Borehole Arrangement
The boreholes are arranged around the shaft along its circumference direction. This time the diameter
of the circumference is decreased as small as possible and the number of the boreholes decreased as well. The
area, which is necessary for the drilling and assembling works, should be reduced. However, excessive
approximation of borehole near the shaft outline may incur damage to the ice-wall. When freezing rock, the ice-
wall may be formed disproportionally according to the arrangement of boreholes. The ice-wall grows rapidly
forward to the shaft center. The thickness t is divided as follows in response to the diameter of the borehole
arrangement. That is it is divide into the thickness 0.6t in the inside direction of shaft and thickness 0.11t in the
outside direction of shaft. Therefore, when designing the freezing process, the arrangement circle diameter of
boreholes is as follows:
D = Ds + 2 ∙ 0.6t + 2a…………………….. (6)
= 12m
Where Ds = sinking diameter of shaft= 7.8m, a = allowable variation of borehole against vertical direction= 1m
The number n of boreholes arranged along the circumferences is divided as the following formula.
n = πD/l ……………………………. (7)
= 31
Where l: interval between boreholes, which is taken as 1.1 ~ 1.8m
The interval between boreholes, is mostly taken as 1.2m and so is used in this equation.
Additional boreholes for 162m required = (15% of 31) = 5
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So, the total number of boreholes, N = 31 + 5 = 36
[Sin K.C. & Young J. (1998) Driving and Mining (Kim Chaek University of Technology) ]
VI. Proposed Design
Ice-wall formation pattern and freezing borehole arrangement found from above calculation regarding
structural design of frozen ground works is shown in Fig. 5.
Fig. 5 Schematic diagram showing freezing borehole layout designed for Khalashpir coal field.
The above figure shows 1.5m spacing between inner radius of ice-wall and radius of shaft. This spacing should
be maintained to prevent unwanted ice encroachment into the excavation area in case of over freezing or erotic
thermal design. Because encroachment of ice into the excavation area would make conventional excavation
difficult, consequently insisting to introduce blasting that will increase cost and time consumption as well,
affecting the overall project target.
6.1 Determination of Ice-wall Stresses for Shallow Shafts (Unstable Ground)
Ice-walls for shafts of shallow depth in soft ground may be designed on elastic criteria. When the relationships
can be expressed in the following equations:
Axial stresses [after Link et al. (1976)]
………………… (8)
= 37041.006 KPa
……………… (9)
= 819.80 KPa
Where 1 = axial stresses due to uniform load p (Fig. 3), *
2 = axial stress due to non-uniform load pl, r =
external radius of ice-wall = 6.17m, rs = radius to centroid of ice-wall = 5.42m, y as in Fig 2, pl = 0.13 ×
hydrostatic pressure= 98.8 KPa.
Bending stresses due to non-uniform load [after Link et al. (1976)]
θ=0andθ=90°...(10)
with …………………… (11)
= 6.5 × 10-6
KPa
Where Ef = Young’s modulus (frozen ground) =2,
I = t3
/12= = = 0.28
So, it is obvious that
1 + 2
*
must always be greater than 2
**
otherwise tensile stresses will develop.
Combined stresses
= 1 + 2
*
± 2
**
………………… (12)
= 37.861 MPa
Allowable stress:
………………. (13)
= 114.730 MPa
The above calculation shows
[Harris J.S, 1995, Ground Freezing In Practice (Thomas Telford Services Ltd, London, 1995]
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For any engineering design of a structure against stress condition should be as such it withstands surrounding
stresses. Allowable stress should be greater than the combined surrounding stresses to ensure its sustainability.
While designing, designer have to ensure allowable pressure in an amount that can compromise erotic design or
any mistaken build up of the structure or failure resulting from unwanted natural condition.
VII. Conclusions
A cost effective and sustainable ice-wall ring formation for sinking a 3.9m shaft in Khalashpir coal field,
freezing works should follow the structural design proposed below:
The 162m long cylindrical ice-wall should be at least 1.5m in thickness
To achieve this 36 equally spaced freeze tubes should be arranged within 12 m diameter
Allowable stress greater than stresses acting on the ice-wall considering safety factor less than 1 shows the
lawfulness of the design.
It should, however, be kept in mind that the estimates obtained from this design are highly approximate and as
such, should be taken as guidelines for decision making processes. These estimates do not replace site specific
detailed analysis and monitoring. Thermal design of the AGF method for shaft sinking in Khalashpir coal field
would be proposed in the next paper.
Notations
The following symbols are used in this paper:
a ─ verticality of shaft
D ─ borehole arrangement diameter
Ds ─ diameter of shaft
Ef ─ Young’s modulus
H ─ depth to be frozen
H ─ head of water
l ─ borehole spacing
rg ─ volume weight of formation
Po ─ overburden pressure
Ph ─ static hydraulic pressure
Pr ─ rock pressure
Q ─ acceleration of gravity
q ─ unconfined compressive strength
r ─external radius of ice-walls
rs ─ radius to centroid of ice-wall
rw ─ density of water
t ─ thickness of ice-wall
— combined stresses
1 ─ axial stresses due to uniform load
2
*
─ axial stress due to non-uniform load
2
**
— bending stresses due to non-uniform
load
a — allowable stress
Ø ─ internal frictional angle of seam
References
[1] China Jinan Mining Development Corporation (2006) Techno-economic Feasibility Study of Khalaspir
Coal Mine Project, Dhaka, Bangladesh (unpublished).
[2] Dr. Yong Om Kil, Khlaspir Coal Mine Project, Pirjang, Rangpur (2005) Pumping Test Report of
Exploration Boreholes on Khlaspir Coal Field (unpublished).
[5] Farazi A. H., Quamruzzaman C., Ferdous N. Mumin A., Mustahid F., Kabir A. K. M. F., (2012)
Selection of Shaft Sinking Method for Underground Mining in Khalashpir Coal Field, Khalashpir,
Rangpur, Bangladesh.
[3] Harris J.S. (1995) Ground Freezing In Practice (Thomas Telford Services Ltd, London).
[4] Korea South-South Cooperation Corporation (1997) Construction of Skip Shaft-1 (Freezing Sinking
Section) Technical Design (unpublished).
[5] Korea South-South Cooperation Corporation (NAMNAM) (2005) Recommendation on Selection of
Conceptional Shaft Location on Khalaspir Coal Field (unpublished).
[6] Sin K.C. & Young J. (1998) Driving and Mining (Kim Chaek University of Technology)