含多个软弱夹层缓倾顺层边坡开挖卸荷变形特征
DEFORMATION CHARACTERISTICS OF GENTLY INCLINED BEDDING SLOPE WITH MULTIPLE WEAK INTERLAYERS UNDER EXCAVATION UNLOADING
向波 1刘正威 2张乐 1闵祥 2邬凯 1郭辉 1李涛2
作者信息
- 1. 四川省公路规划勘察设计研究院有限公司,成都 610041
- 2. 四川公路桥梁建设集团有限公司,成都 610041
- 折叠
摘要
为探究含多个软弱夹层缓倾顺层边坡的开挖卸荷特征,以有限元模拟为手段,依托某在建高速公路顺层边坡,分析分步开挖卸荷后其失稳机制和松弛区范围;然后,考虑软弱夹层的饱水软化效应,研究了顺层边坡的松弛区范围和首次破裂长度特征.结果表明:分步开挖下,含多个软弱夹层缓倾顺层边坡浅表呈坡脚位置处的弧形滑面滑落破坏,滑面由岩土界面剪出;深部呈沿软弱夹层的多层平动式台阶状顺层失稳破坏;松弛区范围随开挖深度的增大而增大,且越靠近地表,松弛区范围向坡体后缘延伸越长;考虑软弱夹层饱水软化效应时,饱水 1 d 后开挖揭露软弱夹层 I 坡体即失稳,稳定性系数降低42.07%,松弛区范围增长 59.22%,首次破裂长度增长 12.51 倍.可见,对含多个软弱夹层的缓倾顺层边坡,开挖前须施作截排水设施,分步开挖时边开挖边支护具有必要性.
Abstract
In order to explore the excavation unloading characteristics of gently inclined bedding slope with multiple weak interlayers,finite element(FEM)simulation was used to investigate the failure mechanism and relaxation region after step-by-step excavation of bedding slope,which from an expressway during construction.Meanwhile,considering the saturated softening effect of weak interlayers,this paper studied relaxation region and initial crack length of bedding slope.The results show that under the step-by-step excavation,the shallow surface of gently inclined bedding slope with multiple weak interlayers is slump slide at the foot of the slope,and the slip surface is cut from the rock-soil interface.However,the deep part of that is a multi-layer translational step-like bedding instability failure along weak interlayers.The relaxation region increases with the increase of excavation depth,and the closer to the surface,the longer the region extends to the trailing edge of the slope.Considering the saturated softening effect of weak interlayers,the slope is failure when the weak interlayer I is exposed after saturated softening 1 d,the stability coefficient decreases by 42.07%,the range of relaxation region increases by 59.22%,and the initial crack length increases by 12.51 times at this point.It is concluded that drainage facilities should be constructed before excavation for gently inclined bedding slope which have multiple weak interlayers,and it is necessary to excavate and support at the same time when excavating step-by-step.
关键词
缓倾顺层边坡/软弱夹层/有限元/失稳机制/松弛区范围/首次破裂长度Key words
gently inclined bedding slope/weak interlayers/FEM/failure mechanism/relaxation region/initial crack length引用本文复制引用
基金项目
交通运输部重点科技项目(2021-ZD1-019)
四川省交通运输科技项目(2021-A-02)
四川省公路规划勘察设计研究院有限公司自立项目(2022-YL-02)
出版年
2024
NETL
NSTL
万方数据