碎石桩复合地基三维地震响应分析
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摘要
将饱和砂土视为土—水两相介质,以Biot动力固结方程为基础,编制了完全耦合的三维排水有效应力动力反应分析程序。利用该程序对碎石桩复合地基进行了动力反应分析。结果表明:在地震荷载作用下,碎石桩具有明显的减震效应,碎石桩复合地基表层的最大水平振动加速度与天然地基相比明显减小,并且碎石桩对地基的沉降变形有明显的抑制作用;碎石桩的排水效应十分显著,随着输入地震加速度的减弱,在孔压达到峰值以后,由下到上出现了明显的孔压消散现象,碎石桩排水效应的影响范围为上窄下宽的圆台形;碎石桩的加密效应显著;考虑碎石桩各效应的耦合作用比仅考虑其单一效应,计算得到的孔压比要小,因此在进行碎石桩复合地基抗液化判别时,应该综合考虑碎石桩各效应的相互耦合作用。
Saturated sand was looked as a soil-water two-phase medium.A fully coupled three-dimension effective-stress dynamic analysis software was developed on the basis of Biot's consolidation theory.Stone columns composite foundation was analyzed using software.The research shows that the reduced vibration effectiveness of stone columns is very remarkable,and the surface maximum horizontal vibration acceleration of stone columns composite foundation is bigger than that of natural foundation.Moreover,the stone columns can restrain settlement of foundation.The drainage effectiveness of stone columns is very remarkable.With decreasing of input earthquake acceleration,the dissipation of pore water pressure starts after the peak value has reached.The effective influence domain of stone columns is a circling platform with narrow upside and wide underside.The densification effectiveness of stone columns is remarkable.The excess pore water pressure ratio considering coupling effectiveness is smaller than that only considering some effectiveness or other.So the coupling effectiveness of stone columns should be considered when judging of anti-liquefaction capability of stone columns composite foundation.
Saturated sand was looked as a soil-water two-phase medium.A fully coupled three-dimension effective-stress dynamic analysis software was developed on the basis of Biot's consolidation theory.Stone columns composite foundation was analyzed using software.The research shows that the reduced vibration effectiveness of stone columns is very remarkable,and the surface maximum horizontal vibration acceleration of stone columns composite foundation is bigger than that of natural foundation.Moreover,the stone columns can restrain settlement of foundation.The drainage effectiveness of stone columns is very remarkable.With decreasing of input earthquake acceleration,the dissipation of pore water pressure starts after the peak value has reached.The effective influence domain of stone columns is a circling platform with narrow upside and wide underside.The densification effectiveness of stone columns is remarkable.The excess pore water pressure ratio considering coupling effectiveness is smaller than that only considering some effectiveness or other.So the coupling effectiveness of stone columns should be considered when judging of anti-liquefaction capability of stone columns composite foundation.
引文
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[9]黄春霞.碎石桩复合地基抗液化性能试验研究[D].北京:北京交通大学,2005.Huang Chunxia.Experimental investigation of anti-liquefaction nature of stone columns composite foundation.Beijing:Beijing Jiaotong University,2006.
[10]蒋鑫,邱延峻,周成.福厦线粉喷桩复合地基有限元分析[J].工程地质学报,2005,13(1):124～128.Jiang Xin,et al..Finite element analysis of embankment founda-tion improved by DJMpiles in Fuzhou-Xiamen railway.Journal of Engineering Geology,2005,13(1):124～128.
[2]Sasaki,Y.&Taniguchi,E..Shaking table tests on gravel drains to prevennt liquefaction of sand deposits[J].Soil and Foundations,1982,22(3):1～14.
[3]王士风.建筑物可液化砂基用砾石排水桩抗震加固的试验研究[D].冶金部建筑研究总院硕士学位论文,1984.Wang Shifeng.The experiment study of the building liquefiable sand foundation reinforced by gravel drainage pile.The Master De-gree Dissertation of the Metallurgical Ministry Building Academe,1984.
[4]Baez,J.I..A design model for the reduction of soil liquefaction by vibro-stone columns[D].Ph.D.Dissertation,University of Southern California,Los Angeles,CA,1995.
[5]林本海,谢定义.复合地基的液化检验理论及其应用[M].北京:中国水利水电出版社,1999.Lin Baihai,Xie Dingyi.The check theory of composite foundation liquefaction and its application.Beijing:China Water Hydroelec-tricity Press,1999.
[6]Korhan Adlier.Ahmed Elgamal.Mitigation of liquefaction and as-sociated ground deformationa by stone columns[J].Engineering Geology,2004,72,275～291.
[7]Zienkiewicz,O.C.,Chang,C.T.and Bettess,P.Drained,Undr-ained,Consolidating ang Dynamic Behavior Assumptions in Soils,Limits of Validity.Geotechnique,1980,(30):385～395.
[8]张艳美.碎石桩复合地基抗液化性能数值模拟及应用研究[D].北京:北京交通大学,2006.Zhang Yanmei.Numerical simulation of anti-liquefaction nature of stone columns composite foundation and application study.Bei-jing:Beijing Jiaotong University,2006.
[9]黄春霞.碎石桩复合地基抗液化性能试验研究[D].北京:北京交通大学,2005.Huang Chunxia.Experimental investigation of anti-liquefaction nature of stone columns composite foundation.Beijing:Beijing Jiaotong University,2006.
[10]蒋鑫,邱延峻,周成.福厦线粉喷桩复合地基有限元分析[J].工程地质学报,2005,13(1):124～128.Jiang Xin,et al..Finite element analysis of embankment founda-tion improved by DJMpiles in Fuzhou-Xiamen railway.Journal of Engineering Geology,2005,13(1):124～128.
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