土石混合体滑坡复活细观结构及力学特性研究

Affected by both the continuous uplifting of Qinghai-Tibet Plateau since the Quaternary and the deep incision of valleys, numerous rock-soil aggregate slides, which composed by glacial (glacioflurial) deposit, alluvial deposits, collapse, landslide and debris flow deposits, are distributed in Southwestern areas of China，many of them have occurred obvious revived deformation, forming a certain type of landslide that is called "revived landslides".The preliminary research results thought that landslides were caused by mesostructure and mechanical proprerties of revived rock-soil aggregate and slip soil. But the actual mesostructure change and mechanics and deformation response are not well understood. In this project, a long-term tracking rock-soil aggregate slide, which took place in the Jiaju village, Danba, Sichuan, is chosen as the study of the object. Based on the digital image acquisition and simulation analysis of typical geological profile, scanning electron microscope of slip soil, direct shear and triaxial compression tests,numerical simulation, three contents will be carried out in our study: (1)to discuss the problems of quantitatively investigating and mechanical properties on mesostructure, and construct reasonable mesostructure, (2)to study the mesoscopic structure evolution and the mechanics and response on the process of revived deformation, and fit the constitutive relation between the mesostructure and the mechanical properties, (3) to reveal controlling mechanism of mesostructure and mechanical properties for revived deformation with the contrast analysis of numerical simulation and monitoring dates on the basis of the researches above, The result will provide supports for further understanding on the mesostructure, the properties, and the stability analysis method of rock-soil aggregate, and so on.

第四纪以来受青藏高原持续隆升及河流深切割作用，我国西南山区发育大量由冰水堆积、冲洪积、崩滑流堆积等形成的土石混合体斜坡，目前，已发生明显复活变形形成滑坡。初步研究认为该类滑坡复活内在原因取决于土石混合体和滑带土细观结构及力学特性，但对其细观结构特征变化和力学特性反应的认识还够深入。本项目拟以长期跟踪的丹巴县甲居土石混合体滑坡为研究实例，采用典型剖面数字图像采集及处理、扫描电镜、直剪和常规三轴实验、数值模拟等手段，初步探讨深切河谷区土石混合体细观结构量化测试及力学特性问题，构建合理的细观结构模型；研究滑坡复活过程中细观结构特征演变及力学和变形特性反应，拟合细观结构与力学特性之间的本构关系；在上述研究基础上开展细观结构及力学特性对滑坡复活影响机制应用研究，并通过数值模拟和监测数据进行对比分析验证。成果将为深入认识该类土石混合体细观结构与特性及稳定性分析方法等提供支撑。

我国西南山区受青藏高原第四纪以来持续隆升作用和发源于青藏高原的长江及其支流等强烈切割，形成典型深切高中山峡谷区。发育大量的由冰川(水)、崩滑流和冲洪积等混杂堆积形成的土石混合体斜坡，不少已发生变形并形成滑坡。本课题系统揭示了大渡河丹巴河段土石混合体滑坡发育特征，进一步厘定和查清了土石混合体的概念、形成条件和年代、发育特征及灾害效应。利用数码图像采集、CT扫描，电镜扫描（SEM）、直接剪切和三轴剪切试验等技术手段对深切河谷演变，土石混合体形成、细观结构及力学特性，斜坡灾变过程和滑坡早期识别等进行了系统研究。实现了深切河谷土石混合体细观结构量化观测，进而构建了典型土石混合体细观结构模型；研究了土石混合体灾变过程及其细观结构的响应，引入了沈珠江二元介质理论和细观力学均匀化 理论，和探讨了土石混合体细观结构与力学和变形特性的相关性。总结了深切河谷地貌演化过程，典型土石混合体斜坡变形破坏模式及滑坡灾变过程，构建了深切河谷土石混合体滑坡早期识别方法及指标体系，研究成果应用于川藏铁路沿线和川西山区深切河谷滑坡早期识别。课题的研究为定量分析深切河谷土石混合体滑坡变形复活主控因素提供了理论基础，为保障深切河谷川藏铁路、城镇、水电、等大型工程的安全建设和运营具有重要的实际应用价值和理论意义。