摘要
基坑多级支护结构随着两级支护间距离B的增加可以分为3种主要的破坏模式,即整体式、关联式和分离式。采用抗剪强度折减法对多级支护达到分离式破坏模式的条件进行了研究,分析了土体强度及第一级支护结构长度L_1和第二级支护结构长度L_2三个主要参数对分离式破坏临界宽度B_(分离)的影响,为了反映土体强度的影响,引入了"独立安全系数比R_(fos)"(即两级间距离无限远时各自安全系数的比值)。计算结果表明,B_(分离)随着R_(fos)的增加而减小,当R_(fos)较小时多级支护结构的破坏模式只存在整体式和分离式,B_(分离)可以根据基于极限分析上限理论的简化算法求得,当R_(fos)超过一定数值B_(分离)达到下限分离式破坏临界宽度,下限分离式破坏临界宽度与两级支护中稳定安全系数较低一级的破坏面宽度一致;B_(分离)随着L1的增加而近似线性增加,B_(分离)随L_2的变化分为两部分,当R_(fos)较小时B_(分离)随L_2的增加而增加,当R_(fos)较大时B_(分离)随L_2的增加而减小。
There are three different failure mechanisms of multi-bench retained foundation pit with different widths of the bench, i.e. overall overturning failure, mutual-effect failure and separate failure. The separate failure mechanism is studied with shear strength reduction method; and the influences of three main factors, i.e. soil strength; the length of first retaining structure L-1 and the length of second retaining structure L-2, to the critical bench width of separate failure B-s, are studied. The results show that the relative stability of the two level retaining structures of the multi-bench system changes with different soil strength. The parameter 'R-fos' is introduced to reflect the influence of the soil strength, which is the ratio of the factor of safeties of the two level retaining structures when they are separated; B-s decreases with the increase of R-fos. A simplified analysis method is proposed to find B-s when R-fos is small; B-s will be constant when R-fos is large enough; B-s increases with the increase of L-1; while it increases with the increase of L-2 when R-fos is small, it decreases with the increase of L-2 when R-fos is large.
出处
《岩土力学》
EI
CAS
CSCD
北大核心
2017年第S1期313-322,共10页
Rock and Soil Mechanics
基金
国家自然科学基金重点项目(No.41630641)
国家自然科学基金项目(No.51308389)
天津市应用基础与前沿技术研究计划(No.14CQNJC07500)~~
关键词
多级支护
基坑
破坏模式
极限分析
强度折减
稳定性
multi-bench retained foundation pit
failure mechanism
limit analysis
shear strength reduction
stability
