摘要
Rock alteration is an important problem of engineering rock mechanics to be solved in Southwest China. X-ray diffraction analysis indicates that rock alteration was formed under specific geological conditions with mineral composition of mainly kaolinite alterated from feldspar. Besides feldspar kaolinization, major types of alteration also include feldspar chloritization in which chlorite replaces some dark minerals (such as biotite and hornblende) in rocks. Rock alteration in the study area is mainly developed in the unloading zone, where NE- and NW-trending faults are found. The surrounding rock heterogeneity such as mineralization, alteration, and structural fault distribution leads to complexity in groundwater system. The chemical composition of groundwater in the transition from dry seasons to rainy seasons and the distribution of strongly permeable zones should be considered in evaluating whether seepage deformations or other engineering problems occur under the high pressure of water permeation.