黄土斜坡渗透冲蚀发展及其失稳模式预测研究

The Loess Plateau is an important cultural and geological resources area in China. However, loess landslides sometimes are very dangerous and induce catastrophic hazards owing to the special characteristics of loess. As the economy develops, they threaten more and more people's lives and property. Hence, the strategy of sustainable development in loess area is already restrained by loess landslides. Based on previously observation, the internal erosion which was caused by seeping water is the main causal factor of catastrophic loess landslide. If we don't understand the mechanism of landslide which was caused by seepage erosion very clearly, we can't present to adequate control measures for mitigation of loess landslides especially in catastrophic cases. Therefore, the integrated research which combines engineering geology, soil mechanics, hydraulic mechanics and sediment dynamics is used to clarify the generation and evolution of seepage erosion phenomena which preceded the loess landslides. Using engineering geology analysis, the nature between landslides and seepage erosion is acknowledged more effective. Using laboratory tests, the hydraulic mechanics and mechanics characteristics of loess are realized more definitely. Using model tests, the seepage deformation and erosion development patterns of loess landslides are understood more clearly. According to the results of engineering geology analysis, laboratory and model tests, the coupled seepage-pipeflow theoretical model and numerical analysis method which are used to analyze and simulate the generation and evolution of internal seepage erosion in loess landslides will be built up more practical. Finally, the stability, step progresses and development of loess landslides will be analyzed and discussed by new numerical method which is built in combining use of coupled seepage-pipeflow analysis, shear strength reduction finite element method (SSRFEM) and computational fluid dynamics (CFD) or discrete element method (DEM). The results of research can also help us to improve mitigation measures for loess landslide hazards such as early warning technique. Consequently, this research not only finds new mitigation idea for catastrophic loess landslides but also contributes science advance to the control principle of loess landslide.

黄土高原是我国重要的国土区域，随着我国西部经济的发展及工程活动的加强，黄土滑坡灾害已成为黄土地区人居与城镇建设安全的重大隐患。然而，受到黄土渗透冲蚀作用的影响，许多的黄土滑坡具有隐蔽性特点，导致了灾难性后果，因此如何减轻和防治具隐蔽性特征的黄土滑坡灾害显得十分迫切和必要。本项目通过工程地质学、土力学、水力学与泥沙动力学等多学科领域的整合研究手段，研究并揭示渗透冲蚀作用对黄土滑坡诱发机理与成灾模式的内在联系关系，建立基于渗流-管流耦合分析的黄土斜坡渗透冲蚀发展的理论模型，研究渗透冲蚀作用下黄土斜坡的稳定性、滑坡失稳模式与演化发展过程。通过项目研究，以期能有效解决困扰黄土滑坡灾害防灾减灾规划的隐蔽性问题，为日后黄土地区的城镇建设、工程建设及防灾减灾作出贡献。

大量的黄土滑坡灾害案例表明，其诱发均与水的作用密切相关，这意味着降雨和灌溉等因素对黄土滑坡的诱发起到了关键性的作用，且部分案例在灾害发生前的预兆很少，进而导致了灾难性后果，这表明目前的黄土滑坡防灾减灾研究工作仍存在诸多的困难与不足，现有的滑坡研究仍无法清楚揭示部分灾难性黄土滑坡的成因机理及其演化发展规律，这迫使我们需重新思考这其中是否存在尚未清楚的“机制”主导着黄土滑坡的“隐蔽性”问题。为了解决这一关键科学问题，本项目从黄土渗透潜蚀特征入手，通过野外的工程地质调研，掌握了黄土斜坡渗透潜蚀的发育规律；为清楚地揭示黄土的入渗及其渗透潜蚀的相关机理，研制了“模块化非饱和土压力板及三轴剪切联合试验系统”、“模块化土体渗透性试验仪”、“渗透潜蚀模型试验仪”与“易于固定、安装和拆卸的防蒸发型双环入渗仪”等试验设备；基于现场入渗试验结果，总结了黄土的入渗规律的特点，并建立了黄土的入渗分区模型；依据黄土的非饱和特性及其入渗规律，提出了“求取现场黄土饱和渗透系数的简化法”；基于渗透潜蚀模型试验结果，总结出黄土渗透潜蚀的特点及其演化发展规律，并揭示了黄土渗透潜蚀与滑坡间的内在联系机理；通过后退式黄土滑坡的演化发展规律及其模型试验结果，提出了“水作用下后退式黄土滑坡特性预测的简化分析方法”。通过项目的研究成果，可为黄土滑坡灾害的防灾减灾工作提供了科学的依据。