主应力轴偏转下软黏土蠕变与土结构状态破坏相互作用机理研究

Long-term deformation and progressive failure of clay slope and foundation primarily influenced by the creep and destructuration of clay on the potential slip surface, where the principal stress rotation always occurs, which results in a decrease of strength, an additional creep deformation and destructuration, and finally disaster occurrence. Present study aims to investigate the creep and destructuration behaviors of clay under different principal stress rotations, and develop a creep model accounting for destructuration and the effect of principal stress rotation. Firstly, drained creep tests using hollow cylinder apparatus are performed, based on which the relationship between creep strain, strain-rates and destructuration state is discussed. Secondly, undrained torsional shear creep tests are carried out to analyze the effects of principal stress rotation on the long-term undrained shear strength. Based on all test results, the creep model with incorporation of effects of destructuration and principal stress rotation is proposed. Finally, the model is implemented into FEM code so as to the long-term deformation and progressive failure of clay slope and foundation can be reasonably predicted. The proposed approach is methodical in its experimental, analytical and numerical characterization of the effects of destructuration and principal stress rotation on creep of clay. The proposed research will also increase understanding the disaster occurrence and its prevention possibility with scientific and practical value.

黏土质坡体或地基长期变形和渐进破坏主要受潜在滑移面上黏土蠕变与土结构状态破坏特性共同影响。由于滑移面上的土受剪切力作用发生明显的主应力轴偏转，导致其强度降低，诱发附加蠕变及土结构破坏，最终引发蠕变灾害。为此，本申请项目拟开展主应力轴偏转下软黏土蠕变与土结构状态破坏相互作用机理研究，建立相应的本构模型。首先采用空心圆柱扭剪仪实现排水蠕变试验，探索不同主应力轴偏转下软黏土蠕变及其速率与土结构状态破坏的相互作用机制；同时，通过不排水扭剪蠕变试验，分析主应力轴偏转与长期不排水抗剪强度折减的相互关系；基于上述试验及规律，建立考虑主应力轴偏转效应的结构性软黏土蠕变模型；最后结合有限元二次开发，形成黏土质坡体或地基长期变形和渐进破坏预测方法。本研究展示主应力轴偏转、软黏土蠕变及土结构状态破坏相互影响的试验、理论及数值等系列成果，为黏土质坡体和地基蠕变灾害防治提供理论依据，具有重要的科学意义和应用价值。

我国是世界上地质灾害最严重、受威胁人口最多的国家之一，其中发生在黏土质坡体和地层上的灾害占有重要比例。黏土质坡体或地基长期变形和渐进破坏主要受潜在滑移面上黏土蠕变与土结构状态破坏特性共同影响。由于滑移面上的土受剪切力作用发生明显的主应力轴偏转，导致其强度降低，诱发附加蠕变及土结构破坏，最终引发蠕变灾害。为此，本申请项目拟开展主应力轴偏转下软黏土蠕变与土结构状态破坏相互作用机理研究，建立相应的本构模型。首先采用空心圆柱扭剪仪实现排水蠕变试验，探索不同主应力轴偏转下软黏土蠕变及其速率与土结构状态破坏的相互作用机制；同时，通过不排水扭剪蠕变试验，分析主应力轴偏转与长期不排水抗剪强度折减的相互关系；基于上述试验及规律，建立考虑主应力轴偏转效应的结构性软黏土蠕变模型；最后结合有限元二次开发，形成黏土质坡体或地基长期变形和渐进破坏预测方法。本研究展示主应力轴偏转、软黏土蠕变及土结构状态破坏相互影响的试验、理论及数值等系列成果，为黏土质坡体和地基蠕变灾害防治提供理论依据，具有重要的科学意义和应用价值。