黄土静态液化导致滑坡转化泥流致灾机理研究

The mud-flow, which with high velocity and long run-out and unexpected the results, initiation from landslide is distribution widely in the Loess Plateau, resulting in more and more catactrophic geo-hazards. This project focus on the mechanism of the mud-flow initiation from landslide due to loess static-liquefaction, summary the characters and model of the mud-flow initiation from landslide according to field investigation at the typical mud-flow events sites. Research the increase and fluctuation characters of pore-water pressure during the mud-flow initiation from landslide due to loess static-liquefaction using triaxial, ring-shear and physical model test, and explain the cause and mechanism of loess static-liquefaction, which resulting in mud-flow initiation from landslide, due to pore-water pressure increasing. Analysis the effect of the water and shear velocity in the process of the mud-flow initiation from landslide. Quantitative evaluation the effect of the saturation level, particle size in the process of the mud-flow initiation from landslide, and then propose the mechanism of the mechanism of the mud-flow initiation from landslide due to loess static-liquefaction. The results of the project will deepen understand the mud-flow, enhance the system of the loess geo-hazards and provide the guidance to mitigation and forecast the mud-flow in Loess plateau.

通过大量的野外调查和室内试验，黄土滑坡在一定的条件下极易转化为远程滑坡，运动状态也从滑动转化为流动，形成泥流，在运动距离和流动速度上远远超出我们所预测范围，从而给黄土地区带来严重的危害。本研究围绕黄土强度劣化导致静态液化促使滑坡转化泥流为轴线，通过对典型滑坡转化泥流的野外调查，概化黄土滑坡转化泥流模式和特征，利用三轴试验、环剪试验和大型物理滑坡模型试验，研究黄土强度劣化导致土体液化转化泥流孔隙水压力增加和波动特征，解释孔隙水压力增加导致黄土强度降低以致产生静态液化的原因和机理，分析水动力、剪切（滑移）速率效应在黄土强度劣化滑坡转化泥流的影响，量化湿度（饱和度）、粒度（黏粒或粉粒含量）等对黄土强度劣化导致滑坡液化转化泥流的影响程度，揭示黄土强度持续劣化导致静态液化转化泥流致灾机理。研究成果有助于深化对黄土泥流的认识，丰富黄土灾害研究体系，并服务于黄土灾害预报和防治

通过大量的野外调查和室内试验，黄土滑坡在一定的条件下极易转化为远程滑坡，运动状态也从滑动转化为流动，形成泥流，在运动距离和流动速度上远远超出我们所预测范围，从而给黄土地区带来严重的危害。本研究围绕黄土强度劣化导致静态液化促使滑坡转化泥流为轴线，开展了黄土强度劣化导致静态液化特征、黄土强度劣化导致静态液化促使滑坡转化泥流动力因素、黄土强度劣化导致静态液化促使滑坡转化泥流影响因素和黄土滑坡液化转化泥流机理四方面的研究。对兰州黑方台、泾阳南缘、延安等典型滑坡转化泥流进行了多次详尽的野外调查，概化出了黄土滑坡转化泥流模式和特征；开展了大量的三轴试验、环剪试验和大型物理滑坡模型试验，再现了水进入黄土的过程，阐明了水进入黄土中“类喀斯特” 侵蚀现象，发现水进入黄土后物理潜蚀表现为以粘粒为主细颗粒的迁移。导致孔隙坍塌，逐渐破坏黄土的结构，促使黄土结构形式从粘化结构到架空结构。揭示了黄土增湿导致的结构应力比降低是导致黄土软化的原因，提出了黄土软化带转化为滑动带起动（突然起动）滑坡的原因：饱和液化，并基于实验证明了液化形式的存在。量化了湿度(饱和度)、粒度(黏粒或粉粒含量)等对黄土强度劣化导致滑坡液化转化泥流的影响程度，揭示黄土强度持续劣化导致静态液化转化泥流致灾机理。基于降雨入渗过程及其衰减规律，构建了黄土地区降雨实时预报模型，开发了基于降雨实时传输的滑坡预报系统，成为目前西安市地质灾害预报的标准，研究成果有助于深化对黄土泥流的认识，丰富黄土灾害研究体系，并服务于黄土灾害预报和防治。提出的黄土强度劣化导致静态液化的无机防护技术，并在固沟保塬工程进行了示范实施。