The uses of pile raft foundations are common in recent years. The combined effect of pile and raf... more The uses of pile raft foundations are common in recent years. The combined effect of pile and raft as foundation can lead to the reduction in total and differential settlements in problematic soil conditions. Many researchers have been done studies to predict the effect of combined pile raft foundations (CPRF) on the response of soil under heavy loads. But most of the numerical studies were done by considering soil as a single layer. The present study aims to find out the effect of pile raft in multi-layered soil using a three-dimensional finite element software PLAXIS 3D. The current parametric study includes the effect of diameter and spacing of piles with varying raft thickness on settlement. It is observed that raft foundation undergoes more settlement than pile raft foundation. The effect of raft thickness has a very little effect on reducing total and differential settlements. The effect of pile diameter and pile spacing was also given useful insight into the behavior of multi...
Granular anchor pile (GAP) system is a modified stone column in which the stone column is reinfor... more Granular anchor pile (GAP) system is a modified stone column in which the stone column is reinforced using an anchor rod with an anchor plate placed at the bottom. The anchor rod is embedded in the footing of the structure which rests on the stone column. This system prevents the uplift of the structure which may be caused by uplift forces like the presence of expansive soil below the footing, wind forces or buoyant forces. This paper presents a review about the application of Granular anchor piles, the conditions in which it can be used and the method of installation. A discussion on the parameters like length, diameter, soil type and its strength which influences the uplift capacity of the granular anchor pile is also given.
Stone columns are usually applied to improve bearing capacity of soft ground. They are also appli... more Stone columns are usually applied to improve bearing capacity of soft ground. They are also applied to tank foundations and nowadays stone columns are increasingly being used in small groups to support isolated footings in soft soils when conventional foundations are considered uneconomical. Stone column are used to increase the time rate of consolidation, reduce liquefaction potential, improve bearing capacity and reduce settlement. They provide primary functions of reinforcement and drainage, and in addition, improve the strength and deformation properties of soft soil in post installation and reconsolidation phase. The major limitation of the stone column is that they undergo excessive bulging, because of very low lateral confinement pressure provided by the surrounding soft clay soil. This limits their use in very soft clays and silts, and organic and peat soils. A new ground improvement method using pervious concrete piles provides higher stiffness and strength that are independent of surrounding soil confinement while offering permeability that is comparable to granular columns. This new method can improve the settlement performance of different structures supported on poor soils. A three dimensional finite element analysis of group of four composite piles consisting of different lengths of pervious concrete and stone aggregate under a square footing using the software package PLAXIS 3D was done. The influence of parameters like cohesive strength of soft clay, modulus of elasticity of pervious concrete and stone aggregate, spacing between piles and length of pervious concrete part of the composite pile on the load carrying capacity of the footing was studied. The results from this study shows that pervious concrete part of the composite pile helps in increasing load bearing capacity of the square footing.
International Journal of Geosynthetics and Ground Engineering, 2018
Geosynthetic encased stone columns (GESCs) are a newly developed technique in which stone columns... more Geosynthetic encased stone columns (GESCs) are a newly developed technique in which stone columns are wrapped with geosynthetic to overcome some of the limitations of ordinary stone columns (OSCs) through the additional confinement provided by the geosynthetic. This paper presents the behavior of GESCs under circular oil storage tank and its comparison with OSCs under the same in situ conditions using PLAXIS 3D. In this paper, initial studies were carried out to understand the mechanism of load carrying capacity of soils reinforced with stone columns and the later observations from the parametric studies supported the conclusions. The various parameters considered in this investigation include the effect of encasement stiffness and length on settlement and lateral deformation of stone columns. The results show that with an increase in stiffness value, there is a considerable reduction in the long-term settlement and lateral deformation of GESCs. It was found that settlement reduced by up to 55% and lateral deformation by up to 68% with an increase in geosynthetic stiffness from 1000 to 10,000 kN/m. Meanwhile the encasement length up to six times the diameter was found as the optimum encasement length to get the same performance as that of fully encased stone columns. Further a suitable arrangement of encased stone columns in terms of encasement length has been developed to economize the consumption of geosynthetic without compromising the performance of GESCs.
The uses of pile raft foundations are common in recent years. The combined effect of pile and raf... more The uses of pile raft foundations are common in recent years. The combined effect of pile and raft as foundation can lead to the reduction in total and differential settlements in problematic soil conditions. Many researchers have been done studies to predict the effect of combined pile raft foundations (CPRF) on the response of soil under heavy loads. But most of the numerical studies were done by considering soil as a single layer. The present study aims to find out the effect of pile raft in multi-layered soil using a three-dimensional finite element software PLAXIS 3D. The current parametric study includes the effect of diameter and spacing of piles with varying raft thickness on settlement. It is observed that raft foundation undergoes more settlement than pile raft foundation. The effect of raft thickness has a very little effect on reducing total and differential settlements. The effect of pile diameter and pile spacing was also given useful insight into the behavior of multi...
Granular anchor pile (GAP) system is a modified stone column in which the stone column is reinfor... more Granular anchor pile (GAP) system is a modified stone column in which the stone column is reinforced using an anchor rod with an anchor plate placed at the bottom. The anchor rod is embedded in the footing of the structure which rests on the stone column. This system prevents the uplift of the structure which may be caused by uplift forces like the presence of expansive soil below the footing, wind forces or buoyant forces. This paper presents a review about the application of Granular anchor piles, the conditions in which it can be used and the method of installation. A discussion on the parameters like length, diameter, soil type and its strength which influences the uplift capacity of the granular anchor pile is also given.
Stone columns are usually applied to improve bearing capacity of soft ground. They are also appli... more Stone columns are usually applied to improve bearing capacity of soft ground. They are also applied to tank foundations and nowadays stone columns are increasingly being used in small groups to support isolated footings in soft soils when conventional foundations are considered uneconomical. Stone column are used to increase the time rate of consolidation, reduce liquefaction potential, improve bearing capacity and reduce settlement. They provide primary functions of reinforcement and drainage, and in addition, improve the strength and deformation properties of soft soil in post installation and reconsolidation phase. The major limitation of the stone column is that they undergo excessive bulging, because of very low lateral confinement pressure provided by the surrounding soft clay soil. This limits their use in very soft clays and silts, and organic and peat soils. A new ground improvement method using pervious concrete piles provides higher stiffness and strength that are independent of surrounding soil confinement while offering permeability that is comparable to granular columns. This new method can improve the settlement performance of different structures supported on poor soils. A three dimensional finite element analysis of group of four composite piles consisting of different lengths of pervious concrete and stone aggregate under a square footing using the software package PLAXIS 3D was done. The influence of parameters like cohesive strength of soft clay, modulus of elasticity of pervious concrete and stone aggregate, spacing between piles and length of pervious concrete part of the composite pile on the load carrying capacity of the footing was studied. The results from this study shows that pervious concrete part of the composite pile helps in increasing load bearing capacity of the square footing.
International Journal of Geosynthetics and Ground Engineering, 2018
Geosynthetic encased stone columns (GESCs) are a newly developed technique in which stone columns... more Geosynthetic encased stone columns (GESCs) are a newly developed technique in which stone columns are wrapped with geosynthetic to overcome some of the limitations of ordinary stone columns (OSCs) through the additional confinement provided by the geosynthetic. This paper presents the behavior of GESCs under circular oil storage tank and its comparison with OSCs under the same in situ conditions using PLAXIS 3D. In this paper, initial studies were carried out to understand the mechanism of load carrying capacity of soils reinforced with stone columns and the later observations from the parametric studies supported the conclusions. The various parameters considered in this investigation include the effect of encasement stiffness and length on settlement and lateral deformation of stone columns. The results show that with an increase in stiffness value, there is a considerable reduction in the long-term settlement and lateral deformation of GESCs. It was found that settlement reduced by up to 55% and lateral deformation by up to 68% with an increase in geosynthetic stiffness from 1000 to 10,000 kN/m. Meanwhile the encasement length up to six times the diameter was found as the optimum encasement length to get the same performance as that of fully encased stone columns. Further a suitable arrangement of encased stone columns in terms of encasement length has been developed to economize the consumption of geosynthetic without compromising the performance of GESCs.
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