The effect of underground columns on the mitigation of liquefaction in shaking table model experiments.pdf (original) (raw)
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International Journal of Innovative Research and Scientific Studies
Several processes allow the improvement of soils such as vibrocompaction, stony columns, static horizontal compaction etc. These processes reduce the risk of liquefaction potential and making it possible to build on this type of soil when the space restriction require it. Stone columns are a recognized method of soil improvement, which consists of creating large diameter columns using special vibrators with granular filling materials introduced into the ground. The objective of this work is to evaluate the effectiveness of stone columns, made in a seismic zone containing liquefiable materials, with regards to the reduction of the risk of liquefaction and the improvement of the bearing capacity of the soil. The approach followed is the exploitation of geotechnical investigation tests (CPT Cone Penetration Test), (SPT: Cone Penetration Test, (pressuremeter tests), carried out before and after soil treatment. This study showed that the network of gravelled columns produces an enhanced ...
The Effectiveness of Stone Column Spacing in Reducing the Potential of Liquefaction
INERSIA lnformasi dan Ekspose Hasil Riset Teknik Sipil dan Arsitektur, 2021
ABSTRACTLiquefaction is a liquefied soil phenomenon caused by cyclic load or earthquake. One of the soil liquefaction prevention methods is the installation of stone column. The stone column is a column filled with compacted rock fragments. It has 50 cm in diameter and 5 m deep This method is believed to reduce the excess pore water pressure that occurs during an earthquake. The stone column has been applied in many construction projects which located in high potential of liquefaction area. This research aims to know the effectiveness of stone column in reducing the liquefaction potential. This research conducted by using borelog data and soil laboratory test. This research also runs the numerical simulation of soil liquefaction with stone column stabilization. The variations in column spacing (2 m; 1.5 m; and 1 m) and subsurface review point (1 m; 1.5 m; 2 m; and 2.5 m) will be applied by using Quake/W from Geostudio 2012 software. The results show that the liquefaction potential c...
Unreinforced Concrete Columns as Countermeasure Against Liquefaction
2018
Soil liquefaction is the complete or partial loss of the bearing capacity of soil, the transition of sand into the state of flow and the formation of a new denser sediment. There are several techniques for improving soil profiles with high liquefaction potential, one of which is soil mixing to form unreinforced concrete column. However, there remains uncertainty over the efficacy of this method, especially if there is a risk of column damage during shaking. This work analyses the performance of the countermeasure, via centrifuge testing, by choosing suitable liquefiable soil materials and following scaling laws to construct the modelled columns with different foundation style. After the soil choice and characterisation and the column construction, the centrifuge samples were prepared and tested for three earthquake motions with different profiles. A loose, unreinforced soil sample made of the same material was also tested for comparison reasons. The soil layers were instrumented wit...
Numerical investigation of stone columns in liquefiable soils
Arabian Journal of Geosciences 15(6):553, 2022
Under earthquake motions, effective stress decreases with pore water pressures. It falls to zero or near-zero values in saturated sandy soils, and consequently, the bearing capacity of the soil is ultimately lost. This phenomenon is called liquefaction. One of the most effective methods used to prevent liquefaction on sandy soils is stone column applications. The stone column applications increase the drainage capacity and the stiffness of the soil. Thus, excess pore water pressure, which develops under dynamic loads, reduces and minimizes liquefaction risks. In this study, the finite element method (FEM) was used with the hypoplastic material model. This model gives more realistic results under repeated loads since the change in the soil unit weight and the effect of the stress level on the soil behavior are taken into account. Since the model was not defined in the ANSYS program, u20p8, a two-phase three-dimensional finite element, was developed for numerical analyses and implemented in the program with the hypoplastic material model. The effect of stone columns to prevent liquefaction on fully saturated sandy soils under dynamic loads and the factors affecting the performance of stone columns were investigated with parametric studies. The results of the analyses revealed the preventive effect of the use of stone columns. They showed that increasing the parameters such as area ratio, hydraulic conductivity, and relative density increased this positive effect more. When the correct designs are made according to the soil properties, the stone column application method provides an effective soil improvement against liquefaction.
Effect of Granular-Column Installation on Excess Pore Pressure Variation during Soil Liquefaction
Ben Salem, Z., Frikha, W., and Bouassida, M. (2015). "Effect of Granular-Column Installation on Excess Pore Pressure Variation during Soil Liquefaction." Int. J. Geomech. , 10.1061/(ASCE)GM.1943-5622.0000516 , 04015046.
During many earthquakes, soil liquefaction causes dramatic damage. The use of a granular column is a ground-improvement technique used to mitigate soil liquefaction. The present paper studies the performance of reinforcement with granular columns as a method for mitigation of potential risk of liquefaction during cyclic loading. The generation and dissipation of excess pore pressure are analyzed by considering the granular-column installation effect. This effect is described by a decrease in horizontal permeability within a disturbed zone around the column, which is described by constant, linear, and parabolic variations. The evolution of excess pore pressure is studied as a function of the disturbed zone in terms of reduced horizontal permeability. Obtained results show that a granular-column installation has a significant influence on the mitigation of liquefaction