胡田飞, 杜升涛. 2016: 基于偏应力的类土质路堑边坡松动区范围分析. 工程地质学报, 24(s1): 1100-1107. DOI: 10.13544/j.cnki.jeg.2016.s1.158
    引用本文: 胡田飞, 杜升涛. 2016: 基于偏应力的类土质路堑边坡松动区范围分析. 工程地质学报, 24(s1): 1100-1107. DOI: 10.13544/j.cnki.jeg.2016.s1.158
    HU Tianfei, DU Shengtao. 2016: ANALYSIS OF LOOSENED ZONE DISTRIBUTION OF SOIL-SIMILAR CUTTING SLOPE BASED ON DEVIATORIC STRESS. JOURNAL OF ENGINEERING GEOLOGY, 24(s1): 1100-1107. DOI: 10.13544/j.cnki.jeg.2016.s1.158
    Citation: HU Tianfei, DU Shengtao. 2016: ANALYSIS OF LOOSENED ZONE DISTRIBUTION OF SOIL-SIMILAR CUTTING SLOPE BASED ON DEVIATORIC STRESS. JOURNAL OF ENGINEERING GEOLOGY, 24(s1): 1100-1107. DOI: 10.13544/j.cnki.jeg.2016.s1.158

    基于偏应力的类土质路堑边坡松动区范围分析

    ANALYSIS OF LOOSENED ZONE DISTRIBUTION OF SOIL-SIMILAR CUTTING SLOPE BASED ON DEVIATORIC STRESS

    • 摘要: 类土质边坡是一种既受岩土体强度控制,又具有显著地质结构面效应的边坡类型,其滑坡机制和塌滑区分布规律区别于一般的岩质和土质边坡。以偏应力为主要评价指标,归纳了通过数值分析法预测类土质边坡松动区范围的方法。以某路堑边坡为案例,采用FLAC3D计算了该边坡在开挖和降雨工况下的稳定性状态,并基于软件内嵌的FISH语言编制了偏应力的后处理程序。结果表明:在开挖卸荷和岩土强度降低的作用下,新生和原始的偏应力等值线会出现增减交叉、分离、重合及梯度突变等现象,并可以反映结构面的响应特征及其对变形的影响,结合塑性区、位移场及施工记录,就可以预测松动区范围和潜在的变形破坏模式。案例边坡一定深度范围内的偏应力场在处于地应力驱动的弹性卸荷状态时会减小,之后由于重力势能的转化作用会增大,进入塑性破坏的非线性卸荷阶段时则显著减小,大变形和滑坡发生后还会出现明显的增减分区现象。相应地,边坡在开挖过程中先后表现为卸荷回弹、裂缝扩展与浅表层溜坍,降雨工况时发生沿全强风化交界面的顺倾滑塌,达到整体饱和状态后进而产生深层的圆弧型滑坡。

       

      Abstract: The stability of soil-similar slope is controlled by the strength of soil mass and geological structural planes simultaneously, and its mechanism of landslide and distribution of slide zone are quite different from those of rock slope and homogeneous soil slope. In this study, a numerical analysis method, which is mainly based on the deviatoric stress, was proposed to predict the loosened zone distribution of the soil-similar slope. This method was performed by the FLAC3D software, and the post-processing program for deviatoric stress was written by the FISH language. A cutting slope was chosen for the case verification, and its stability state in both excavation and rainfall condition was calculated. It is shown that the new and original deviatoric stress contours will be characterized by the phenomena of cross, separation, coincidence or gradient mutation, which are especially remarkable near the structural planes. So the potential failure mode and range of loosened zone can be found out according to change of deviatoric stress contours, on the combination with plastic zone, displacement field and construction record. For the slope case in excavation condition, the deviatoric stress decreased at the early elastically unloading state driven by crustal stress; then increased because of the transformation of gravitational potential energy; and decreased again when getting into nonlinear unloading stage of plastic damage. After large deformation and landslide took place, obvious partition between increase and decrease of deviatoric stress would come into being. Correspondingly, the slope in excavation condition was characterized by the unloading rebound, crack propagation and shallow slide in sequential order fundamentally. The completely weathered stratum slid along the interface with the intensely weathered stratum in rainfall condition, and deep landslide with circular slip-surface occurred further in overall saturated state.

       

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