摘要
在滑坡孕育与发展的过程中由于外部条件的不均匀作用,使得滑坡局部位置出现应力集中。当集中剪应力大于滑带的峰值抗剪强度时,滑带发生应变软化。多余的剪应力将发生转移并由临近滑带承担,滑坡发生渐进破坏。针对顺层缓倾浅层滑坡,考虑后缘推力作用,将推移式滑坡的渐进破坏过程分为5个阶段。基于力学平衡与变形协调关系,建立了各阶段浅层滑坡的渐进破坏力学模型。在综合分析滑坡渐进破坏过程的基础上,给出了不同渐进破坏阶段的临界荷载与划分判据。重新表征了不同应力状态下滑带的抗剪强度,给出了滑坡各渐进破坏阶段的稳定性系数计算公式,物理含义更加明确。最后将建立的力学模型应用于简单浅层滑坡,实现了后缘推力-坡体位移-剪应力分布-稳定性系数一一对应的定量关系。模型较好地体现了滑坡渐进破坏过程中滑带土抗剪强度变化的时空特性。与不平衡推力的计算结果对比分析表明,采用峰值强度在工程设计中是偏危险的,采用残余强度则是不经济的,论证了运用渐进破坏理论对滑坡进行工程设计的必要性。
During the gestation and development of landslides, due to the uneven effect of external conditions, local stress concentration occurs in the landslide. Once the concentrated shear stress is greater than the peak shear strength of sliding zone, the strain-softening behavior of sliding zone appears. The redundant shear stress will be transferred and be borne by the adjacent sliding zone, then the progressive failure in slope will happen. The progressive failure process of the thrust-type gently inclined shallow landslide is divided into five stages considering the back edge thrust. The progressive failure mechanical models for different stages are established based on the coordination of mechanical balance and deformation. The critical loads and criteria for different progressive failure stages are given by the comprehensive analysis of the progressive failure process of the landslide. The shear strength of sliding zone in different stress states is re-characterized, the stability coefficient of each progressive failure stage of the landslide is given, which makes the physical meaning more clear. Finally, the established mechanical model is applied to a simple shallow landslide, and the quantitative relationship among the back edge thrust, slope displacement, shear stress distribution and stability coefficient is achieved. The model well reflects the space-time characteristics of the mobilized shear strength of sliding zone in the progressive failure process of landslides. By comparing with the calculation results of unbalanced thrust method, results show that it is dangerous to adopt peak strength in engineering design, but uneconomical to adopt residual strength. It is necessary to use progressive failure theory in engineering design of landslide.
作者
张龙飞
吴益平
苗发盛
李麟玮
康田
ZHANG Long-fei;WU Yi-ping;MIAO Fa-sheng;LI Lin-wei;KANG Tian(Faculty of Engineering,China University of Geosciences,Wuhan,Hubei 430074,China)
出处
《岩土力学》
EI
CAS
CSCD
北大核心
2019年第12期4767-4776,共10页
Rock and Soil Mechanics
基金
国家自然科学基金（No.41572278）
国家重点研发计划（No.2017YFC1501301）~~
关键词
应变软化
浅层滑坡
渐进破坏
稳定性分析
strain-softening
shallow landslide
progressive failure
stability analysis
