高速公路碎石桩复合地基加固数值模拟
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摘要
通过数值模拟分析了高速公路碎石桩复合地基在桩体施工、路堤填筑、运行期全过程问题和地震动荷载作用等问题。计算结果表明:碎石桩在路堤的填筑和运行期起到明显的排水固结作用,当桩长大于6 m后复合地基中的孔压最大值变化较缓慢;在桩长大于10 m后路堤底面的沉降量和坡脚的水平位移量变化均较小。地震荷载作用下路堤顶部的水平向加速度峰值较底面大;在碎石桩加固范围内,复合地基的水平刚度大于天然地基,而在整个地基内,复合地基的竖向刚度均大于天然地基,在地基刚度较大的情况下位移最大值较大;天然地基在路堤坡脚下方、路堤边坡等位置较易发生液化,经过碎石桩加固后降低了地基液化的可能性。
A numerical analysis is studied on the construction,runtime and earthquake condition of composite ground reinforced by stone columns.The calculated results indicate that the stone columns have significant effect on drainage of the excess pore pressure under construction and runtime;when the pile length is larger than 6 m,the maximum pore pressure changes slowly;when it is larger than 10 m,the settlement under embankment and horizontal displacement under slope toe change slowly.Under earthquakes the maximum acceleration at the top of the pave is larger than that at the bottom of the model;in reinforced scope,the horizontal stiffness of composite ground is larger than that of natural foundation;in the whole ground,the vertical stiffness of composite ground is larger than that of natural foundation,and the maximum displacement is larger in large stiffness ground;the toe position and slope of embankment are easy to be liquefied under earthquakes,but stone column composite ground can reduce the possibility of liquefaction.
A numerical analysis is studied on the construction,runtime and earthquake condition of composite ground reinforced by stone columns.The calculated results indicate that the stone columns have significant effect on drainage of the excess pore pressure under construction and runtime;when the pile length is larger than 6 m,the maximum pore pressure changes slowly;when it is larger than 10 m,the settlement under embankment and horizontal displacement under slope toe change slowly.Under earthquakes the maximum acceleration at the top of the pave is larger than that at the bottom of the model;in reinforced scope,the horizontal stiffness of composite ground is larger than that of natural foundation;in the whole ground,the vertical stiffness of composite ground is larger than that of natural foundation,and the maximum displacement is larger in large stiffness ground;the toe position and slope of embankment are easy to be liquefied under earthquakes,but stone column composite ground can reduce the possibility of liquefaction.
引文
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[2]HAN J,YE S L.Simplified method for consolidation rate ofstone column reinforced foundations[J].Journal ofGeotechnical and Geoenvironmental Engineering,ASCE,2001,127(7):597–603.
[3]赵明华,邓岳保,杨明辉.路堤荷载作用下碎石桩复合地基桩土应力比计算及试验研究[J].岩土力学,2009,30(9):2623–2628.(ZHAO M H,DENG Y B,YANG M H.Calculation and model test for pile-soil stress ratio of gravelpile composite foundation under embankment load[J].Rockand Soil Mechanics,2009,30(9):2623–2628.(in Chinese))
[4]赵明华,孙建兵,张永杰,等.碎石桩复合地基复合模量极限值分析[J].中南大学学报,2009,40(6):1718–1723.(ZHAO M H,SUN J B,ZHANG Y J,et al.Limit value ofcomposite modulus of gravel pile composite foundation[J].Journal of Central South University,2009,40(6):1718–1723.(in Chinese))
[5]ADALIER K,ELGAMAL A,MENESES J,et al.Stonecolumns as liquefaction countermeasure in non-plastic siltysoils[J].Soil Dynamics and Earthquake Engineering,2003,23:571–584.
[6]ADALIER K,ELGAMAL A.Mitigation of liquefaction andassociated ground deformation by stone columns[J].Engineering Geology,2004,72:275–291.
[7]刘义怀,朱志铎,刘松玉.路堤荷载下碎石桩复合地基的有限元分析[J].公路交通科技,2002,19(5):11–13.(LIUYi-huai,ZHU Zhi-duo,LIU Song-yu.Finite element methodfor composite foundation with stone columns[J].Journal ofHighway and Transportation Research and Development,2002,19(2):11–13.(in Chinese))
[8]河南工业大学.高速公路粉土地基碎石桩复合地基加固机理数值模拟及应用研究[R].郑州:河南工业大学,2011.(Henan University of Technology.Numerical Simulation ofStone Column Reinforced Expressway Foundation and itsApplication[R].Zhenzhou:Henan University of Technology,2011.(in Chinese))
[9]沈珠江,徐刚.堆石料的动力变形特性[J].水利水运科学研究,1996(2):143–150.(SHEN Zhu-jiang,XU Gang.Deformation of rock materials under cyclic loading[J].Hydro-Science and Engineering,1996(2):143–150.(inChinese))
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