软土地基中包裹碎石桩地震动力响应数值模拟研究

Numerical study on seismic response of geosynthetic encased stone column in soft clay foundation

包裹碎石桩是将碎石桩包裹在土工合成材料中,通过土工合成材料的径向约束作用,减少碎石桩的变形,提高其在软土地基中的稳定性。使用有限差分程序FLAC3D进行模拟,研究地震荷载作用下软土地基中包裹碎石桩的动力响应。数值模型采用考虑滞回特性的非线性弹塑性模型模拟碎石桩和软土,使用线弹性土工格栅单元模拟土工合成材料。利用振动台试验结果验证三维动力数值模型,然后开展参数分析,研究筋材刚度、软土剪切模量、路堤荷载等参数对软土地基中包裹碎石桩地震动力响应的影响规律。数值模拟结果表明:随着筋材刚度的增加、软土剪切模量的增加、竖向荷载的减小,碎石桩的沉降及筋材应变和土体的剪应变也显著减小,土工合成材料包裹筋材可以有效提高碎石桩的抗震性能。

Geosynthetic can be used as an encasement for conventional stone column,forming geosynthetic encased stone column(GESC).This method can reduce the lateral displacements of stone column and improve the bearing capacity in soft clay through the radial restraint of geosynthetic encasement.This paper presents a numerical study to investigate the dynamic response of GESC in soft clay foundation.Both the stone column and the soft clay were characterized using nonlinear elasto-plastic models that consider the hysteretic behavior.Geosynthetic encasement was characterized using linearly elastic geogrid elements.The 3D dynamic numerical model was validated using shaking table test results published.A parametric study was conducted to investigate the influences of geosynthetic encasement stiffness,soft clay shear modulus,and embankment loading on the dynamic response of GESC in soft clay foundation.The results show that with the increase of geosynthetic encasement stiffness and soft soil shear modulus,the decrease of embankment load,the settlement of stone column and the strains of geosynthetic encasement and soils could be significantly reduced.Geosynthetic encasement could effectively improve the seismic performance of stone column in soft clay foundation.