砂埋管道上浮地基破坏机理的离散元模拟  

Uplift Mechanism of Buried Pipe in Sand Ground Using DEM

作　　者：蒋明镜[1,2] 廖兆文 张望城[1,2] 王华宁[3] 

机构地区：[1]同济大学地下建筑与工程系,上海200092 [2]同济大学岩土及地下工程教育部重点实验室,上海200092 [3]同济大学航空航天与力学学院,上海200092

出　　处：《地下空间与工程学报》2015年第6期1506-1513,共8页Chinese Journal of Underground Space and Engineering

基　　金：国家杰出青年基金(51025932);教育部博士点基金(20100072110048);国家自然科学基金(10972158)

摘　　要：本文采用离散单元法(DEM)建立的砂土中管道上浮模型来研究管道上浮时地基的破坏机理。首先考察不同密实度砂土在不同围压下的宏观力学特性,然后通过土体局部变形和颗粒位移场等微观变量分析不同密实度和不同埋深比对管道上浮地基破坏模式和上浮抗力的影响。结果表明:伴随土体变形,上覆土体的渐进破坏主要分布在上覆土体区域和管道周围;松砂中,与应力-应变关系类似,上浮抗力随着上浮位移的增长呈硬化性增长,管道周围土体回填进管道下部形成的空隙中,呈现局部流动破坏模式;密砂中,上浮抗力随着上浮位移的增加先上升后下降,规律与应变软化一致,管道上方先剪切形成倒梯形的上覆土楔,然后管道周围土体回填下部空隙形成流动,呈现先整体剪切破坏后局部流动的破坏模式;随着埋深的增加,上浮抗力增加,密砂中以先整体剪切破坏为主,同时局部流动破坏有明显的趋势。This paper aims to model the uplift failure mechanism of buried pipe in sand ground with respect to the effects of pipe cover ratio and ground soil density by using the discrete element method（ DEM）. The mechanical properties of soil with different confining pressures and densities are firstly observed via biaxial compression test. Then the pipe uplift failure mechanism is studied under different pipe cover ratios and sand densities by investigating the uplift resistance,heave at ground surface and deformed ground. The results show that in loose sand ground,the uplift resistance increases to a stable value with the increase of pipe uplift distance and the soils flow around the pipe to show the local flow failure mechanism. While in dense sand,the uplift resistance rises sharply to a peak value and afterwards drops to a residual value with the increase of uplift distance. Four stages are indentified in dense cases,i.e. mobilization of peak uplift resistance,infilling of soil beneath the pipe,formation of shear bands,and flow of soils around the pipe. With increasing the cover ratio,it reveals that flow of soils around the pipe tends to be apparent even in dense cases.

关 键 词：砂埋管道 密实度 埋深比 上浮破坏 离散单元法 

分 类 号：O319.56[理学—一般力学与力学基础]