中文摘要：

东河口滑坡是“5．12”汶川大地震触发的典型高速远程滑坡，滑坡自高程1300m处开始滑动，总滑程约2400m，致使780余人遇难。滑坡体主要由震旦系灰岩及白云质灰岩、寒武系炭质板岩及干枚岩构成。野外调研结果表明，以上几种岩石的自身微观结构及宏观力学性质，对于促使该滑坡在地震作用下发生迅速启动有着至关重要的作用。为此，利用ORTHOPLAM显微镜、RMT-150C岩石力学试验系统及600kN液压式万能材料试验机，分别对岩石的显微结构及抗拉、抗压、抗剪断性质进行一系列试验研究。显微结构测试结果表明，这几种岩石的结构及矿物成分均比较复杂，大多经历至少两期的变形与变质过程：岩石力学试验结果表明，水对该滑坡体岩石的力学性质有着重要影响，在干燥状态与饱水状态下，岩石的抗拉强度、抗压强度以及抗剪断强度均有很大的差异，同时，岩石中原有的结构面也是影响其力学性质的一个重要因素。

英文摘要：

Donghekou landslide is a typical rapid and long run-out landslide located in Qingchuan County triggered by the 2008 great Wenchuan earthquake. It starts from the elevation of 1 300 m and causes 780 deaths, with a total long run-out of 2 400 m. This landslide is composed of limestone and dolomite limestone of Sinian system, carbon slate and phyllite of Cambrian system. Field investigations indicate that as for the Donghekou landslide, the microstructure and macroscopically mechanical property of the rock on sliding mass play an important role in the starting-up of the landslide under the action of earthquake. Therefore, by using the ORTHOPLAM microscope, the RMT - 150C rock mechanics testing system and the 600 kN hydraulic universal testing machine, a series of tests have been carried out to study the microstructures and mechanical properties, such as the tensile strength, the compression strength and the shear strength of rocks from Donghekou landslide. The microstructure test results show that the mineral component of rock samples is very complex, and most of the rocks have experienced more than two deformation and metamorphic processes. And the mechanical test results indicate that water is an important factor for the mechanical properties of rocks, and the tensile strength, the compression strength and the shear strength are different at the dried state and saturated state. At the same time, the structural plane also plays a significant role in the mechanical properties of rocks.