中文摘要：

水与岩土相互作用是导致岩土抗剪强度降低的主要原因之一,这种宏观表象是地下水与岩土发生了一系列复杂的力学、物理和化学方面相互作用的综合结果。因此,查明水与岩土的相互作用模式是掌握岩土抗剪强度变化机理的关键所在。本文以兰州地区红层风化泥岩为对象,采用直剪试验方法,初步探讨了快剪条件下,孔隙水化学成分及pH改变时,该类风化泥岩抗剪强度的变化特点。结果显示,在快剪条件下,水在该类风化泥岩抗剪强度中的力学效应（孔隙水压力效应）与物理、化学效应同时存在,但力学效应明显强于物理效应和化学效应。地下水物理效应和化学效应的强弱与风化泥岩可溶盐含量及其化学成分、粘粒含量及其矿物成分有关。

英文摘要：

Water-soil /rock interaction is one of the key causes leading to reduction of shear strength of soil/rock. This is actually resulted from a series of complicated mechanical,physical and chemical interactions between pore water and soil/rock. Investigating these interactions is therefore a key to the understanding insight in variation of soil /rock＇s shear strength,which are functions of types of soil /rock and groundwater. In this paper,the interactions between the weathered red mudstone and pore water in Lanzhou area,China were preliminarily explored by means of direct shear testing. It was found that under the fast shearing condition,mechanical （pore water pressure）,physical and chemical effects function together making shear strength variation of the weathered red mudstone,and that mechanical effect is the strongest. The physical and chemical effects are closely associated with abundance of clay minerals and soluble salt within the weathered red mudstone.