陕北砂性黄土滑塌变形破坏机制研究

A particular type of landslide are widely developed in north of Shaanxi, which is called the loess collapse. It has the slides characteristics and topples characteristics at the same time. These collapses are mainly due to the tension cracks at the top of the slope or due to the shearing deformation at the feet of the slope and which one appeared firstly are still unclear. These puzzles not only confused the field investigation but also accused different opinions among experts..The project will do field investigations widely, summarize the macro deformation and failure futures, construct the geology conception model. It will select the typical true landslides as the models, use the centrifugal testing to simulate the slope deformation accused by triggering factors and slopes conditions, acquire quantify failure parameters. It will use numerical simulation methods, reproduce the process of slope deformation and failure, and simulate the stress-strain distribution at different conditions. Finally it will synthesize the macro deformation and failure futures, quantify failure parameters, and numerical simulation results to expound the deformation and failure mechanism of this kind of landslide, providing the basis for further micro mechanism study.

在陕西的北部地区广泛存在一种兼具"滑坡"和"崩塌"特性的特殊地质灾害类型-黄土滑塌，关于它的变形破坏机制，是以上部拉裂式崩塌为主，还是以底部剪切式滑移为主？是先行出现拉张裂隙，还是先在坡脚出现蠕变变形？不仅在野外调查中常使人迷惑，不同的专家看法也不一。.本项目在广泛的野外调查基础上，总结归纳其宏观变形破坏特征，建立地质概念模型。选取典型原型，通过离心试验，物理模拟不同诱发因素和坡体条件对斜坡变形破坏量的响应关系，获取定量化的变形破坏指标。利用数值模拟，再现破坏过程，并模拟不同条件下的应力-应变场分布和变形破坏。综合研究其宏观变形破坏特征、定量化的变形破坏特征和数值模拟的变形破坏特征，阐明该类滑塌的变形破坏过程和机制，为进一步的微观机理研究提供基础。

黄土滑塌是一种独特的而又在中国的黄土高原北部区域常见的滑坡，其危害性很大。但由于其规模小，因而研究程度很低。本课题以大量的野外调查为基础，并通过室内土工试验和离心机物理模型试验等手段，从黄土滑塌的分布、发育的典型地质环境、触发因素、变形破坏机制、风险特征这几个方面，对该类黄土滑坡进行了综合研究。得到主要结论如下：黄土滑塌在黄土高原北部的砂黄土带最为严重，向东南方向逐渐减轻。它多发生在黄土沟壑系统的幼年期—青年期沟谷中，当地开挖山坡建窑洞的居住模式，易引发黄土滑塌的产生。黄土滑塌的诱发因素有降雨、冻融、冻胀、人工开挖、地震、灌溉、坡顶加载等，而且多种诱发因素往往共同作用。其变形破坏机制为斜坡中下部剪切破坏—上部拉张破坏—中下部剪切破坏，且这一过程可反复进行，形成了黄土滑塌的不断后退性发展。黄土滑塌有“坍窑不坍掌”的风险特征，这可用于指导该地区的地质灾害应急救援工作。