摘要
砂土液化问题一直是土动力学与岩土地震工程研究领域的重要课题之一.基于南水北调中线一期工程总干渠漳河河漫滩段工程,通过现场和室内试验获取岩土体的动力学参数,利用岩土数值分析FLAC3D软件,砂土本构模型选为Finn模型,输入近场地邯郸台记录的实际地震波,对渠基砂土地震液化和渠道变形破坏特征进行了动力数值分析.结果表明,在地震作用下,超静孔隙水压力最大值位于渠堤底部砂土层中,但渠堤底部砂土层由于初始应力较大,其孔压比不高,不会发生液化;在渠道底部以及渠堤外侧坡面平台至坡脚局部区域土体虽然超孔隙水压力较小,但有效应力小,超孔压比反而大,砂土层发生了液化;在地震作用下变形主要发生在渠堤和浅层地基土里,具有对称性;渠堤边坡的变形破坏主要表现为在渠堤顶面发生震陷和拉裂破坏,在坡脚处发生水平侧向流动和挤压隆起变形.计算过程中,在渠堤及地基的不同位置设置监测点,得到了地震作用过程中不同位置处超孔隙水压力、有效应力和位移的动态变化规律.通过剪应变增量判断,在地震力作用下渠堤及地基中形成了贯通的剪切滑动面,易发生整体滑动破坏.研究成果对南水北调砂土液化特性的认识和防治有一定的意义.
The sand liquefaction problem has been one of the important topics in soil dynamics and geotechnical earthquake engineering. Taking Zhanghe River floodplain segment of middle-route of the South-to-North Water Diversion Project for an example,the sand liquefaction,deformation and failure characters of sand are predicted by FLAC3 D. The results show that,the maximum excess pore water pressure is in the sand soil layer at the bottom of the canal bank. for the initial stress is high and the pore pressure ratio is low,sand liquefaction-at the bottom of the canal bank will not occur. Yet at the foundation of the channel and the local area from the outside platform to the foot of the slope,although the excess pore water pressure is small,the effective stress is also small,so the excess pore pressure ratio is large and the sand layer liquefied. Deformation occurs mainly in the canal bank and shallow foundation soil under the earthquake and it is symmetric. Deformation forms of the slope are mainly seismic subsidence and tensile failure on the top of the canal bank,and the lateral flow and extrusion uplift occurs at the foot of the slope. Monitoring points are arranged in different locations around the bank and foundation of the canal during the calculation. Dynamic variation rules of the excess pore water pressure,effective stress and displacement at different locations are obtained under earthquake. By the shear strain increment,it could be judged according to the shear strain increment that,under the earthquake force,the shear sliding plane through the bank and foundation of the canal is formed,which prone to trigger overall slides failure. The research result is significant in prevention and cure of sand liquefaction of the South-to-North Water Diversion Project.
出处
《应用基础与工程科学学报》
EI
CSCD
北大核心
2015年第3期421-429,共9页
Journal of Basic Science and Engineering
基金
国家自然科学基金青年基金资助项目(41102203)
水利部公益性行业科研专项经费项目(201301034)
河南省科技创新人才计划
河南省基础与前沿技术研究项目(122300410146)
华北水利水电大学青年科技创新人才支持计划项目
关键词
砂土液化
Finn本构模型
超孔压
孔压比
变形破坏
剪应变增量
sand liquefaction
Finn constitutive mode
excess pore water pressure
pore pressure ratio
deformation and failure
shear strain increment
