摘要
Abstract
Longyangxia is located at the junction of Gonghe County and Guinan County in Hainan Tibetan Autonomous Prefecture,Qinghai Province,in the northeastern part of the Qinghai-Tibet Plateau.It has strong geological structures and complex engineering geological condi-tions.During the exploration stage of the Longyangxia Energy Storage Project,granite alteration with obvious zonal characteristics was exposed in the powerhouse area.To study the correlation between the alteration characteristics of granite,the deterioration mechanism of its physical-mechanical properties,and cave collapse,and to establish an alteration classification system suitable for engineering geological surrounding rock evaluation,this study adopted survey methods including on-site geological mapping,exploration adits,mineral composition analysis,la-boratory tests,large-scale shear tests,deformation tests,point load tests,and geophysical wave velocity tests.The results show that the granite alteration mainly involves the transformation of minerals such as K-feldspar and plagioclase into clay minerals like illite and montmo-rillonite.Compared with fresh rock mass,the main mechanical indexes of the altered granite have decreased significantly;moreover,the cave collapse caused by rock mass alteration is highly correlated with the closure conditions and duration.By sorting out and summarizing the test parameters,and combining the on-site alteration scale,scope,and degree,this study proposes to integrate the granite alteration degree with the rock mass weathering degree,classify the altered rock mass according to the engineering geological surrounding rock evaluation method,and evaluate the impact of the altered rock mass on the stability of underground caves.关键词
岩体蚀变特征/物理力学性质/蚀变程度划分/工程地质评价Key words
rock mass alteration characteristics/physical-mechanical properties/alteration degree classification/engineering geological evaluation分类
地质学
