强震条件下顺层滑坡堵江的动力灾变机理与演化全过程

我国西南地区地震频发，触发的岩质滑坡数量多、规模大、破坏力强，且往往造成滑坡堵江灾害。震害调查表明，大型堵江滑坡多见顺层岩质边坡，呈高速、短程、整体状运动特征。以汶川地震典型堵江顺层滑坡为依托，概化原型边坡工程地质模型，以DDA方法建立大变形运动学计算力学模型，引入强度衰减式块间接触模型、动态式滑体前锋压水阻尼和底部泥沙摩阻模式，对DDA数值程序进行二次开发，模拟强地震触发下滑坡堵江的动力演化过程，并基于水上-水下全程PIV量测技术的大型振动台试验进行验证；进而系统模拟不同斜坡地形与岩层组构、河水动力条件（水深和河床泥沙厚度）、地震荷载等主控因素下滑体堵江运动的完整演化过程，揭示其动力灾变机理和堵江模式；通过变动参数比较研究，建立各主控参数与滑体速度、前锋位置、入江体积、堰塞体高度等相应关系，提出地震滑坡堵江判据。该成果可为地震滑坡堵江预测、防灾减灾规划和地震应急处置对策制定提供科学依据。

China is a country with frequent earthquake-induced landslide river-blocking disasters. Especially in the southwest area of the China, these river-blocking landslides are of large quantity, strong destructive force and severe damage. Post-earthquake geologic investigations of these disasters indicate that most of the large-scale river-blocking landslides with the characteristics of “high speed, short routine and monolithic type” generally occur in the bedding rock slope. Based on the typical bedding landslide and the river-blocking barrier dam occurred during the Wenchuan earthquake, the geological engineering model can be obtained through the generalization of the actual slope. Utilizing the discontinuous deformation analysis (DDA) method to formulate the kinetic and computational mechanic model focused on large deformation, and redeveloping the DDA code by introducing the strength degradation contact model between adjacent blocks, dynamic damping of water pressure before the front edge of sliding body and frictional resistance of soil or sand at the bottom of sliding body, the whole dynamic evolution process of landslide river-blocking under actual seismic conditions can be reproduced and be validated by large-scale shaking table test relied on the PIV measurement technique throughout the whole depth of water. Then, in order to reveal the mechanism of dynamic catastrophe process and river-blocking pattern, simulating the complete process of river-blocking motion induced by sliding body systematically with various main affecting factors, such as valley topography, composition and structure of rock, hydrodynamics conditions (river width, water depth and river bed sediment thickness, etc ) , seismic loadings, and so on. In addition, conducting the comparative studies on various main control parameters to establish the relationships between main parameters and the velocity of sliding body, the final position, the volume of sliding body immerged into water, the height of barrier dam, etc. to put forward the general criterion of landslide river-blocking. The achievements of this research item can provide the scientific evidences for prediction of landslide river-blocking and disaster prevention and mitigation in earthquake regions.