an experimental stud y on effects of diameter on … · 2017-07-24 · column. a typical prototype...

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International Journal of Civil Engineering and Technology (IJCIET)Volume 8, Issue 7, JulyAvailable online at ISSN Print: 0976 © IAEME

AN EXPERIMENTAL STUDDIAMETER ON LOAD CAR

SVNI

SVNI

ABSTRACTThis paper investigates th

Geosynthetically encased floating stone column. A detailed laboratory experimental study is carried out on ordinary as well as on Geosynthetically encased floating stone column. The unit cell idealization technique is used instone columns in all the test are kept 300 mm and the diameter varying 45 mm, 50 mm, 55 mm and 60 mm. The stress response at 40 mm prescribed settlement is measured. The stress vs. settlement results is plotted and comparetrends obtained from graph shows that by increasing the diameter of stone column the stressdesign reinforced floating stone column for improving the soKey wordsGeosynthetic encasement, diameter of stone column, prescribed settlement, stresssettlement responseCite this ArticleEffects of Diameter on Load Carrying Capacity oStone Column2017, pp. 88http://www.iaeme.com/IJCIET/issues.

1. INTRODUCTIONSoil having very less uthe building foundation over such problematic soil is failed due to excessive settlement column technique is an ideal ground improvement technique to get rid on such problematic


International Journal of Civil Engineering and Technology (IJCIET)Volume 8, Issue 7, JulyAvailable online at http://www.iaeme.com/IJCIET/issues.ISSN Print: 0976-6308 and ISSN Online: 0976

© IAEME Publication


OF GEOSYNTHETICALLY FLOATING STONE COLUM

SVNIT- Sardar Vallabhbhai National Institute of Technology, Surat

SVNIT- Sardar Vallabhbhai National Institute of Technology, Surat

ABSTRACT This paper investigates th

Geosynthetically encased floating stone column. A detailed laboratory experimental study is carried out on ordinary as well as on Geosynthetically encased floating stone column. The unit cell idealization technique is used instone columns in all the test are kept 300 mm and the diameter varying 45 mm, 50 mm, 55 mm and 60 mm. The stress response at 40 mm prescribed settlement is measured. The stress vs. settlement results is plotted and comparetrends obtained from graph shows that by increasing the diameter of stone column the stress- settlement response is decreases. The findings in this study are helpful to design reinforced floating stone column for improving the soKey words: Soft soil, ordinary stone column, unit cell, floating stone column, Geosynthetic encasement, diameter of stone column, prescribed settlement, stresssettlement responseCite this ArticleEffects of Diameter on Load Carrying Capacity oStone Column.2017, pp. 88–96http://www.iaeme.com/IJCIET/issues.

INTRODUCTIONSoil having very less uthe building foundation over such problematic soil is failed due to excessive settlement column technique is an ideal ground improvement technique to get rid on such problematic

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International Journal of Civil Engineering and Technology (IJCIET)Volume 8, Issue 7, July 2017, pp.

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Publication



Research Scholar, Applied Mechanics Department, Sardar Vallabhbhai National Institute of Technology, Surat

Professor,Sardar Vallabhbhai National Institute of Technology, Surat

This paper investigates thGeosynthetically encased floating stone column. A detailed laboratory experimental study is carried out on ordinary as well as on Geosynthetically encased floating stone column. The unit cell idealization technique is used instone columns in all the test are kept 300 mm and the diameter varying 45 mm, 50 mm, 55 mm and 60 mm. The stress response at 40 mm prescribed settlement is measured. The stress vs. settlement results is plotted and comparetrends obtained from graph shows that by increasing the diameter of stone column the

settlement response is decreases. The findings in this study are helpful to design reinforced floating stone column for improving the so

Soft soil, ordinary stone column, unit cell, floating stone column, Geosynthetic encasement, diameter of stone column, prescribed settlement, stresssettlement response Cite this Article: H. K. Sarvaiya and C. H. SolankiEffects of Diameter on Load Carrying Capacity o

. International Journal of96.

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INTRODUCTION Soil having very less unconfined compressive strength the building foundation [3]. In many case studies it is reported that the foundation constructed over such problematic soil is failed due to excessive settlement column technique is an ideal ground improvement technique to get rid on such problematic

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International Journal of Civil Engineering and Technology (IJCIET)2017, pp. 88–96, Article ID: IJCIET_08_07

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H. K. SarvaiyaResearch Scholar, Applied Mechanics Department,

Sardar Vallabhbhai National Institute of Technology, Surat

C. H. SolankiProfessor, Applied Mechanics Department,


This paper investigates the effects of diameter on Geosynthetically encased floating stone column. A detailed laboratory experimental study is carried out on ordinary as well as on Geosynthetically encased floating stone column. The unit cell idealization technique is used instone columns in all the test are kept 300 mm and the diameter varying 45 mm, 50 mm, 55 mm and 60 mm. The stress response at 40 mm prescribed settlement is measured. The stress vs. settlement results is plotted and comparetrends obtained from graph shows that by increasing the diameter of stone column the


Soft soil, ordinary stone column, unit cell, floating stone column, Geosynthetic encasement, diameter of stone column, prescribed settlement, stress

H. K. Sarvaiya and C. H. SolankiEffects of Diameter on Load Carrying Capacity o

International Journal of

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nconfined compressive strength In many case studies it is reported that the foundation constructed

over such problematic soil is failed due to excessive settlement column technique is an ideal ground improvement technique to get rid on such problematic

asp 88

International Journal of Civil Engineering and Technology (IJCIET)Article ID: IJCIET_08_07

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Indexed



H. K. SarvaiyaResearch Scholar, Applied Mechanics Department,


C. H. SolankiApplied Mechanics Department,


e effects of diameter on Geosynthetically encased floating stone column. A detailed laboratory experimental study is carried out on ordinary as well as on Geosynthetically encased floating stone column. The unit cell idealization technique is used instone columns in all the test are kept 300 mm and the diameter varying 45 mm, 50 mm, 55 mm and 60 mm. The stress response at 40 mm prescribed settlement is measured. The stress vs. settlement results is plotted and comparetrends obtained from graph shows that by increasing the diameter of stone column the



H. K. Sarvaiya and C. H. SolankiEffects of Diameter on Load Carrying Capacity o

International Journal of Civil Engineering and Technology

asp?JType=IJCIET&VType=8&IType=7

nconfined compressive strength In many case studies it is reported that the foundation constructed


International Journal of Civil Engineering and Technology (IJCIET)Article ID: IJCIET_08_07_0


AN EXPERIMENTAL STUDY ON EFFECTS OF DIAMETER ON LOAD CARRYING CAPACITY


H. K. Sarvaiya Research Scholar, Applied Mechanics Department,


C. H. Solanki Applied Mechanics Department,


e effects of diameter on stressGeosynthetically encased floating stone column. A detailed laboratory experimental study is carried out on ordinary as well as on Geosynthetically encased floating stone column. The unit cell idealization technique is used in this entire studystone columns in all the test are kept 300 mm and the diameter varying 45 mm, 50 mm, 55 mm and 60 mm. The stress response at 40 mm prescribed settlement is measured. The stress vs. settlement results is plotted and compared with untreated soil. The trends obtained from graph shows that by increasing the diameter of stone column the



H. K. Sarvaiya and C. H. Solanki, An Experimental Study on Effects of Diameter on Load Carrying Capacity of Geosynthetically Encased Floating

Civil Engineering and Technology


nconfined compressive strength is considered as problematic soil for In many case studies it is reported that the foundation constructed


[email protected]

International Journal of Civil Engineering and Technology (IJCIET) 010


Y ON EFFECTS OF RYING CAPACITY

OF GEOSYNTHETICALLY ENCASED FLOATING STONE COLUMN

Research Scholar, Applied Mechanics Department, Sardar Vallabhbhai National Institute of Technology, Surat, Gujarat, India

Applied Mechanics Department, Sardar Vallabhbhai National Institute of Technology, Surat, Gujarat, India

stress-settlement Geosynthetically encased floating stone column. A detailed laboratory experimental study is carried out on ordinary as well as on Geosynthetically encased floating stone

this entire studystone columns in all the test are kept 300 mm and the diameter varying 45 mm, 50 mm, 55 mm and 60 mm. The stress response at 40 mm prescribed settlement is measured.

d with untreated soil. The trends obtained from graph shows that by increasing the diameter of stone column the

settlement response is decreases. The findings in this study are helpful to design reinforced floating stone column for improving the soft soil.


An Experimental Study on f Geosynthetically Encased Floating

Civil Engineering and Technology


is considered as problematic soil for In many case studies it is reported that the foundation constructed

over such problematic soil is failed due to excessive settlement [6 and 12].column technique is an ideal ground improvement technique to get rid on such problematic

[email protected]



ENCASED N

, Gujarat, India

, Gujarat, India

settlement behaviourGeosynthetically encased floating stone column. A detailed laboratory experimental study is carried out on ordinary as well as on Geosynthetically encased floating stone

this entire study. The length of stone columns in all the test are kept 300 mm and the diameter varying 45 mm, 50 mm, 55 mm and 60 mm. The stress response at 40 mm prescribed settlement is measured.


settlement response is decreases. The findings in this study are helpful to

Soft soil, ordinary stone column, unit cell, floating stone column, Geosynthetic encasement, diameter of stone column, prescribed settlement, stress-


Civil Engineering and Technology, 8(7),



]. The encased scolumn technique is an ideal ground improvement technique to get rid on such problematic

[email protected]



, Gujarat, India

, Gujarat, India

behaviour of Geosynthetically encased floating stone column. A detailed laboratory experimental study is carried out on ordinary as well as on Geosynthetically encased floating stone

. The length of stone columns in all the test are kept 300 mm and the diameter varying 45 mm, 50 mm, 55 mm and 60 mm. The stress response at 40 mm prescribed settlement is measured.


settlement response is decreases. The findings in this study are helpful to

-


8(7),


The encased stone column technique is an ideal ground improvement technique to get rid on such problematic

An Experimental Study on Effects of Diameter on Load Carrying Capacity of Geosynthetically Encased Floating Stone Column

http://www.iaeme.com/IJCIET/index.asp 89 [email protected]

soil [2 and 8]. It is proven that by using encased stone column technique, not only improve the settlement characteristics but also improve the consolidation parameters of soft soil which is equally beneficial to the building foundation as bearing capacity [14]. Due to extensive use of encased stone column to improving a very soft ground, it is required to check physical dimensions and quantities of stone column material used needed for the ground improvement. It is proven from previous studies that the full encasement length is not required for effective load carrying behaviour of stone column, the half encasement length to the stone column carry equal load as load carried by full encased stone column [9 and 11]. However the full encasement helps to transfer load at greater depth. Meanwhile the lateral dimensions of stone column need to be study for the effectiveness and economic of technique. In present study the labouratory experimental work is carried out to check the effects of diameter on stress- settlement behaviour of ordinary as well as Geosynthetically encased floating stone column in unit cell tank with controlled strain condition.

2. EXPERIMENTAL CONSIDERATIONS The entire load test is conducted on unit cell [10]. The actual field stone column installation there for scale down to understand the exact behaviour of the stone column in laboratory [7]. The laboratory unit-cell modelled as a cylindrical tank of having rigid and smooth inside boundary so that when a stone column installed in middle of unit cell is represented as symmetry in all direction [1]. The area influencing the stress due to installation of stone column is considered as a unit-cell area. There is a no stress beyond the boundary of unit cell tank. This concept is used to predict the load settlement behaviour of stone column [4].

According to IS 15284 (part 1): 2003, the influence of load is within the equivalent diameter [10]. The triangular pattern was considered to design the unit cell tank. A cylindrical unit-cell tank of 300 mm diameter and 600 mm height was used for load tests on single stone column. A typical prototype stone column diameter varies from 0.6 to 1 m and length from 5 - 20 m. usually, L/d ratio in the prototype stone column varies between 5 and 20, in which L and d are the column length and diameter respectively. Based on this, the L/d ratio in the model tests was adopted 3 to 8 for single stone column.

3. MATERIALS PROPERTIES Soil used is of CL type based on modified soli classification system and collected at a depth of 2 m, from SVNIT college campus, Surat, Gujarat, India. Collected clay was air-dried and pulverized. The pulverized clay was sieved through 2 mm sieve for easy mixing and quicker hydration. The particle size distribution is shown in fig. 1. A series of undrained shear strength tests were carried out to determine the water content corresponding to undrained shear strength 30 kPa of clay. The resulting water content of the clay was found to be 30%. This amount of water content was kept same in all tests. Other properties of clay soil are given in table 1.

H. K. Sarvaiya and C. H. Solanki


Table 1 Properties of clay

Properties Values Classification (IS: 1498-1970) CL Specific Gravity 2.6 Liquid Limit 45% Plastic Limit 20% Plasticity Index 25% Clay Content 35% Silt Content 60% Max. Dry Density 17 kN/m3 Optimum Moisture Content 18% Undrained Shear Strength kPa 30 kPa Bulk unit weight at 30% water content 18.5 kN/m3

Figure 1 Grain size distributions of clay and stone aggregate for laboratory model test

Table 2 Property of stone column material

Properties Values Angle of internal friction (Deg.) 42 Particle size 2-10 mm Uniformity coefficient 2 Coefficient of curvature 1.125 Specific gravity 2.75 Dry unit weight 18.5 kN/m3 Unified soil classification system GP

Crushed stones (aggregates) of size between 2 to 10 mm have been used to form stone column. The aggregate size distribution is shown in Fig. 1. The stone column aggregate material soaked for 24 hours before charging into the casing pipe in order to prevent it from absorbing the moisture from the surrounding clay soil. Other properties of stone column aggregate are summarized in table 2.

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The woven Geosynthetic fabrics namely TF-422 is used for reinforcing the floating stone column cylindrically. The Geosynthetic material is cut and stitched as per required length and diameter. The cylindrical diameter of the stitched Geosynthetic was same as the inside diameter of the casing pipe. The stress elongation behaviour observed from standard wide-width tension tests [5] as shown in figure. 2.

Figure 2 Stress Vs Strain behavior of Techno Fabric TF- 422 type of geosynthetics

4. PREPARATION OF CLAY BED IN UNIT CELL TANK In all the tests, an identical technique is adopted to prepare the clay bed. A series of unconfined compressive strength (UCS) tests are carried out for different moisture content and the moisture content correspond to 30 kPa is selected to prepare clay bed in all the tests. The amount of water content was found to be 30% and this amount of water content is kept same in all tests to maintain similar properties throughout the tests. Soil was pulverized well with 30% of water content. Before preparing the clay bed the pulverized clay was stored for 24 hours so that the moisture can distribute evenly.

A thin coat of oil at the inner surface of unit cell tank was applied to reduce the friction between clay and the tank wall before filling the pulverized clay in to unit cell. Soil was filled in the tank in 6 layers with measured quantity by weight. Each layer was compacted uniformly by hand to achieve approximately 100 mm height. Stone column was constructed by displacement method. A thick casing pipe of 2 mm wall thickness with base plate at the end was pushed into the soil up to a required depth to construct a stone column. The external diameter of casing pipe was kept similar as required diameter of stone column is 55mm. Outer surface of the casing pipe was lubricated by applying a thin layer of oil for easy penetration and withdrawal without any significant disturbance to the surrounding soil. For ordinary stone column, casing pipe was pushed into the soil along with a base plate having a circular groove to accommodate the casing pipe in order to prevent the soil from entering the pipe during the installation. Stones aggregates were charged into the hole in layers in measured quantities to achieve a compacted height of 120 mm. The pipe was then raised in stages ensuring a minimum of 5 mm penetration below the top level of the placed stone column aggregate. To achieve a uniform unit weight, compaction was done with a 2 kg circular steel bar with 10 blows of 100 mm drop to each layer. This light compaction effort was adopted to ensure that there is no significant lateral bulging of the column which creates disturbance to the surrounding soft soil. Unit weight of stone columns was estimated with the quantity of

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aggregate consumed for the construction and the volume of the stone column. The correspopulled out, the base plate remains in the soil. The procedure was repeated until the column was completed to the full height.

In case of construction of geosynthetically reinfwith geosynthetic encasement wrapped inside the casing pipe was slowly pushed into the clay bed vertically and concentrically in the unit cell tank, until it reached up to required depth. Static force was applied to in the clay soil . The displaced clay was come out at the surface during the installation was taken out. Further procedure is similar as ordinary stone column.

5. TEST PROCEDUREA typical tethe experiments are conducted on floating stone columns in homogeneous clay beds in unit cell tanks. The loadgeosynthetics has been studied by applying the vertically load over it with the help of triaxial testing machine as shown in fig. machine at constant displacement rate of 0.24 mm/min. the displaavoid any possibility of squeezing out of soil particle from the clay bed and to avoid the generation of extra pore pressure in the clay bed. The approx. 5 mm seating load was applied before counting the actual settlement. The sto the diameter of stone column was used to transfer the uniformly distributed load over stone column. The plate was directly rested over the stone column and the uniform loading was applied over the steel pLVDT.


aggregate consumed for the construction and the volume of the stone column. The corresponding unit weight of stone column was found to be 18 kN/m3. When casing pipe is pulled out, the base plate remains in the soil. The procedure was repeated until the column was completed to the full height.

In case of construction of geosynthetically reinfwith geosynthetic encasement wrapped inside the casing pipe was slowly pushed into the clay bed vertically and concentrically in the unit cell tank, until it reached up to required depth. Static force was applied to in the clay soil . The displaced clay was come out at the surface during the installation was taken out. Further procedure is similar as ordinary stone column.

TEST PROCEDUREA typical test arrangement for ordinary and reinforced stone column is shown in Fig. the experiments are conducted on floating stone columns in homogeneous clay beds in unit cell tanks. The loadgeosynthetics has been studied by applying the vertically load over it with the help of triaxial testing machine as shown in fig. machine at constant displacement rate of 0.24 mm/min. the displaavoid any possibility of squeezing out of soil particle from the clay bed and to avoid the generation of extra pore pressure in the clay bed. The approx. 5 mm seating load was applied before counting the actual settlement. The sto the diameter of stone column was used to transfer the uniformly distributed load over stone column. The plate was directly rested over the stone column and the uniform loading was applied over the steel p

Figure 3

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aggregate consumed for the construction and the volume of the stone column. The nding unit weight of stone column was found to be 18 kN/m3. When casing pipe is

pulled out, the base plate remains in the soil. The procedure was repeated until the column was completed to the full height.

In case of construction of geosynthetically reinfwith geosynthetic encasement wrapped inside the casing pipe was slowly pushed into the clay bed vertically and concentrically in the unit cell tank, until it reached up to required depth. Static force was applied to push the casing pipe into the soil so as to minimize the disturbance in the clay soil . The displaced clay was come out at the surface during the installation was taken out. Further procedure is similar as ordinary stone column.

TEST PROCEDURE st arrangement for ordinary and reinforced stone column is shown in Fig.

the experiments are conducted on floating stone columns in homogeneous clay beds in unit cell tanks. The load-settlement behaviour of stone column encased with and without usingeosynthetics has been studied by applying the vertically load over it with the help of triaxial testing machine as shown in fig. machine at constant displacement rate of 0.24 mm/min. the displaavoid any possibility of squeezing out of soil particle from the clay bed and to avoid the generation of extra pore pressure in the clay bed. The approx. 5 mm seating load was applied before counting the actual settlement. The sto the diameter of stone column was used to transfer the uniformly distributed load over stone column. The plate was directly rested over the stone column and the uniform loading was applied over the steel plate. The corresponding deformation is measured with the help of

3 Schematic diagram for load test on single stone column in a unit cell


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pulled out, the base plate remains in the soil. The procedure was repeated until the column was completed to the full height.

In case of construction of geosynthetically reinfwith geosynthetic encasement wrapped inside the casing pipe was slowly pushed into the clay bed vertically and concentrically in the unit cell tank, until it reached up to required depth.

push the casing pipe into the soil so as to minimize the disturbance in the clay soil . The displaced clay was come out at the surface during the installation was taken out. Further procedure is similar as ordinary stone column.

st arrangement for ordinary and reinforced stone column is shown in Fig.

the experiments are conducted on floating stone columns in homogeneous clay beds in unit settlement behaviour of stone column encased with and without usin

geosynthetics has been studied by applying the vertically load over it with the help of triaxial testing machine as shown in fig. 3. The vertical load was applied through a triaxial testing machine at constant displacement rate of 0.24 mm/min. the displaavoid any possibility of squeezing out of soil particle from the clay bed and to avoid the generation of extra pore pressure in the clay bed. The approx. 5 mm seating load was applied before counting the actual settlement. The sto the diameter of stone column was used to transfer the uniformly distributed load over stone column. The plate was directly rested over the stone column and the uniform loading was

late. The corresponding deformation is measured with the help of

Schematic diagram for load test on single stone column in a unit cell


asp 92


pulled out, the base plate remains in the soil. The procedure was repeated until the column

In case of construction of geosynthetically reinfwith geosynthetic encasement wrapped inside the casing pipe was slowly pushed into the clay bed vertically and concentrically in the unit cell tank, until it reached up to required depth.


st arrangement for ordinary and reinforced stone column is shown in Fig. the experiments are conducted on floating stone columns in homogeneous clay beds in unit

settlement behaviour of stone column encased with and without usingeosynthetics has been studied by applying the vertically load over it with the help of triaxial

. The vertical load was applied through a triaxial testing machine at constant displacement rate of 0.24 mm/min. the displaavoid any possibility of squeezing out of soil particle from the clay bed and to avoid the generation of extra pore pressure in the clay bed. The approx. 5 mm seating load was applied before counting the actual settlement. The steel plate of 10mm thickness and diameter equals to the diameter of stone column was used to transfer the uniformly distributed load over stone column. The plate was directly rested over the stone column and the uniform loading was






In case of construction of geosynthetically reinforced stone column, a casing pipe along with geosynthetic encasement wrapped inside the casing pipe was slowly pushed into the clay bed vertically and concentrically in the unit cell tank, until it reached up to required depth.




. The vertical load was applied through a triaxial testing machine at constant displacement rate of 0.24 mm/min. the displaavoid any possibility of squeezing out of soil particle from the clay bed and to avoid the generation of extra pore pressure in the clay bed. The approx. 5 mm seating load was applied

teel plate of 10mm thickness and diameter equals to the diameter of stone column was used to transfer the uniformly distributed load over stone column. The plate was directly rested over the stone column and the uniform loading was




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orced stone column, a casing pipe along with geosynthetic encasement wrapped inside the casing pipe was slowly pushed into the clay bed vertically and concentrically in the unit cell tank, until it reached up to required depth.




. The vertical load was applied through a triaxial testing machine at constant displacement rate of 0.24 mm/min. the displacement rate chosen so as to avoid any possibility of squeezing out of soil particle from the clay bed and to avoid the generation of extra pore pressure in the clay bed. The approx. 5 mm seating load was applied




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push the casing pipe into the soil so as to minimize the disturbance in the clay soil . The displaced clay was come out at the surface during the installation was



. The vertical load was applied through a triaxial testing cement rate chosen so as to

avoid any possibility of squeezing out of soil particle from the clay bed and to avoid the generation of extra pore pressure in the clay bed. The approx. 5 mm seating load was applied




[email protected]




push the casing pipe into the soil so as to minimize the disturbance in the clay soil . The displaced clay was come out at the surface during the installation was

st arrangement for ordinary and reinforced stone column is shown in Fig. 3. All the experiments are conducted on floating stone columns in homogeneous clay beds in unit

settlement behaviour of stone column encased with and without using geosynthetics has been studied by applying the vertically load over it with the help of triaxial

. The vertical load was applied through a triaxial testing cement rate chosen so as to

avoid any possibility of squeezing out of soil particle from the clay bed and to avoid the generation of extra pore pressure in the clay bed. The approx. 5 mm seating load was applied





6. EXPERIMENTAL PROGRAM There are series of load tests performed to check the stress-settlement behaviour of floating stone column with and without geosynthetic encasement. It includes the load test on only clay bed, on an ordinary stone column and load test on Geosynthetically encased floating stone column. Table 3 shows the lists of experiment performed to check the effects of diameter on stress- settlement behaviour of ordinary as well as on geosynthetic reinforcement floating stone column. To know the effects of diameter of TF-422 type geosynthetic reinforcement, the diameter of stone column is varying from 45 mm, 50 mm, 55 mm and 60 mm of ordinary and encased floating stone column with ength of stone column kept constant 300 mm.

Table 3 Experiment program to check the effects of diameter of stone column

Sr. No. Diameter mm Reinforcement length (mm)

Stone column Length (mm)

Type of Reinforcement General Type

1 55 (Loading Plate Size) - - - Only Clay Bed

2 45 - 300 - OSC 3 50 - 300 - OSC 4 55 - 300 - OSC 5 60 - 300 - OSC 6 45 300 300 TF- 422 RSC 7 50 300 300 TF- 422 RSC 8 55 300 300 TF- 422 RSC 9 60 300 300 TF- 422 RSC

7. RESULTS AND DISCUSSIONS The load- settlement response results obtained from the test are compared with ordinary stone column. TF-422 type geosynthetic material is wrapped to the stone column and the effects of varying diameter on stress-settlement response from each test are plotted.

7.1. Effects of diameter of stone column without reinforcement (Ordinary stone column) The list of experiment is carried out to know the effects of diameter of floating stone column to improve the soft soil as shown in table 3. The length of stone column was kept 300 mm for the entire test and the diameter was changed 45 mm, 50 mm, 55 mm and 60 mm. The results obtained from load test are shown in graphical form. Figure 4 shows the stress vs. settlement responses of OSC with varying diameter. The results were compared well with the untreated soil. The stress response at 40 mm prescribed settlement was measured as 1092, 1114, 1060 and 997 kPa for the diameter of 45, 50, 55 and 60mm of OSC respectively. The stress response improved 2.89, 2.95, 2.80 and 2.64 times higher compared to untreated soil respectively. It shows that the stress response decreases with increase of stone column diameter. So the stress-settlement response of slender column is high compared to thicker column.



Figure 4 Stress vs. settlement responses of OSC with varying diameters

7.2. Effects of diameter of stone column with TF-422 geosynthetic reinforcement (Reinforced stone column) The list of experiment was carried out to know the effects of diameter of stone column with TF-422 type reinforcement to improve the soft soil as shown in table 3. The length of stone column was kept 300 mm for all the experiments and the diameter was changed 45 mm, 50 mm, 55 mm and 60 mm. the full length encasement of TF-422 type reinforcement was provided. The results obtained from load test are shown in graphical form. Figure 5 shows the stress vs. settlement responses of RSC with varying diameter. The results are compared well with the untreated soil. The stress response at prescribed 40 mm settlement was measured as 1541, 1398, 1277 and 1175 kPa for the diameter of 45, 50, 55 and 60mm of RSC with TF-422 type reinforcement respectively. The stress response improved 4.08, 3.70, 3.70, 3.38 and 3.11 times higher compared to untreated soil respectively. It shows that the stress response decreases with increase of stone column diameter.

Figure 5 Stress vs. settlement responses of RSC with varying diameters

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8. CONCLUSIONS A series of laboratory model test have been performed on single stone column in unit cell tank under floating condition to study the effects of diameter of TF-422 type Geosynthetic encasement. For all tests the length of floating stone column is 300 mm and with diameter varying from 45 mm, 50 mm, 55 mm and 60 mm. The stress response at 40 mm prescribed settlement is measured and the load settlement results are compared with those results obtained from load test of untreated clay bed. Based on the results obtained from experiments, following concluding remarks extracted.

The stress-settlement response increases by providing geosynthetic encasement to the floating stone column.

By increasing the lateral dimention of floating stone column the stress-settlement response decreases.

The stress- settlement response of 45 mm dimeter of floating stone column if high compred to 60 mm diameter of floating stone column.

REFERENCES [1] A. Hanna, M. Etezad, T. Ayadat, “Mode of failure of a group of stone columns in soft

soil”, Int J Geomech, 13 (1) (2013), pp. 87-96.

[2] Alexiew, D., Brokemper, D., and Lothspeich, S. (2005). “Geotextile Encased Columns (GEC): Load capacity, geotextile selection and pre-design graphs.” Geotech., Spec. Pub No. 130–142, 497–510.

[3] Ali K., Sharma K.G, and J.T Shahu, Behaviour of Reinforced Stone Columns in Soft Soils an Experimental Study, Indian Geotechnical Conference, pp:625 – 628, 2010.

[4] A.P. Ambily and S.R. Gandhi, “Behavior of stone columns based on experimental and FEM analysis”, Journal of Geotechnical and Geoenvironmental Engineering (ASCE), 133 (2007), pp. 405-415.

[5] ASTM D4595 – 17, “Standard Test Method for Tensile Properties of Geotextiles by the Wide-Width Strip Method”.

[6] Black, J. A., Sivakumar, V., Madhav, M. R., and Hamill, G. A. (2007). “Reinforced stone columns in weak deposits: Laboratory model study.” J. Geotech. Geoenviron. Eng., 133(9),

[7] Castro, J., Karstunen, M. and Sivasithamparam, N. 2014. Influence of stone column installation on settlement reduction. Computers and Geotechnics, 59, 87-97.

[8] Gniel J, Bouazza A (2009), “Improvement of soft soils using geogrid encased stone columns”, J Geotextiles Geomemberane 27:167–175.

[9] H. K. Sarvaiya and C. H. Solanki (2017), “A Study on Effect of Length of Geosynthetic Encasement Material on Floating Stone Column”, International Journal of Civil Engineering and Technology (IJCIET), Volume 8, Issue 6, pp. 977–985,

[10] IS 15284 (part 1): 2003, “Design and construction for ground improvement guidelines for stone column”.

[11] Majid Khabbazian, Christopher L. Meehan, and Victor N. Kaliakin (2010) Numerical Study of Effect of Encasement on Stone Column Performance, GeoFlorida 2012, February 20-24, 2010, Orlando, Florida, United States



[12] Paulus P. Rahardjo (2014), “Geotechnical Failures Case Histories of Construction on Soft Soils, Forensic Investigations and Counter Measures in Indonesia”, International Journal of Integrated Engineering, Vol 6, No 2. Pp. 11-23.

[13] Murugesan, S. & Rajagopal, K. (2009). Studies on the behavior of single and group of geosynthetic encased stone columns. Journal of Geotechnical and Geoenvironmental Engineering, 136, No. 1, 129–139.

[14] Zhang, Y., Chan, D. & Wang, Y. (2012). Consolidation of composite foundation improved by geosynthetic-encased stone columns. Geotextiles and Geomembranes, 32, June, 10–17.

[15] H. K. Sarvaiya and C. H. Solanki, A Study on Effect of Length of Geosynthetic Encasement Material On Floating Stone Column, International Journal of Civil Engineering and Technology, 8(6), 2017, pp. 977–985.

[16] SK. Abdul Rehaman and M. Suresh Babu, Seismic Analysis of Framed Structures with and without Floating Columns. International Journal of Civil Engineering and Technology, 8(3), 2017, pp. 1070-1076

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