关键词: 蚀变辉绿岩；蚀变特征；围岩分级；蚀变指数；模糊评判；硬梁包水电站；大波河

Abstract: Altered diabase is one of the common rock masses in engineering construction in western China, and its alteration degree has a great influence on the characteristics of engineering rock mass. In this paper, the altered diabase of the Yingliangbao Hydropower Station under construction on Dadu River was taken as the research object, and the types of altered diabase were classified according to the macroscopic geological characteristics, rock mineralogical characteristics and mechanical test results, and the fuzzy mathematical theory was introduced to classify the degree of surrounding rock of altered diabase. The results show that a wide distribution of diabase alteration zones in the project area was formed under the complex geological tectonic action, and the altered diabase could be divided into six categories: micro-altered diabase, cataclastic diabase, cracked diabase, diabase breccia, schistose diabase and argillaceous diabase. With the enhancement of alteration degree, the fragmentation of diabase and the clay mineralization degree of kaolinite and chlorite gradually increased, and the corresponding mechanical strength gradually decreased. According to the alteration characteristics of diabase, the saturated uniaxial compressive strength, cohesion, integrity coefficient, structural plane characteristic parameters and alteration index were selected as the basis for surrounding rock classification, and a fuzzy comprehensive evaluation method for the classification of altered diabase surrounding rock was established, and the correspondence between rock types and surrounding rock grades was obtained. Finally, taking the multiple altered diabase zones in two excavated diversion tunnels of the power station as an example, the feasibility and rationality of the method were verified. The surrounding rock evaluation results are in good agreement with the 现场情况，indicating that the method has good applicability.

Key words: altered diabase; alteration characteristics; surrounding rock classification; alteration index; fuzzy evaluation; Yingliangbao Hydropower Station; Dadu River