The scale and characteristics of rock mass are important indexes of the rock mass structural plane classification.This paper firstly analyzes the spatial distribution characteristics,the structural plane types(original structural plane,tectonic structural plane and hypergenic structural plane) and the associated features of the Emeishan basalts and then studies the classification schemes of the built hydropower structure planes of different rock areas(the east district,the central district and the west district) in the Emeishan basalt distribution area,Southwest China.Based on the analysis and comparison of the scale and the engineering geological characteristics of the typical structure planes in the basalt hydroelectric Stations,the types of structural planes are used in the first order classification.The secondary order classification is made by considering the impact factors of rock mass quality,e.g.,the state of the structural planes,infilling,joint opening,extending length,the grade of weathering and strength.The engineering geological classification for Emeishan basalt is proposed.Because there are no evidences of a large structure presenting in study area,the first-order(Ⅰ) controlling structural planes do not appear in the classification,there only appear Ⅱ,ⅡⅠ,Ⅳ and Ⅴ grade structural planes influencing the rock-mass quality.According to the different rock-block types in bedding fault zone,the second-grade(Ⅱ) structural planes consisted of bedding fault zone is further classified into Ⅱ_1,Ⅱ_2 and Ⅱ_3.The third-grade(ⅡⅠ) structural planes constructed by intraformational faulted zones are not subdivided.According to the different characteristics of intrusion,alteration and weathering unloading structural planes,the Ⅳ grade structure plane is divided into Ⅳ_1,Ⅳ_2 and Ⅳ_3.According to the development characteristics of joints and fractures,the Ⅴ grade structure plane is divided into fracture Ⅴ_1 and columnar joint Ⅴ_2.In all,the structural planes are classified into four
SUN Shu-qinHUANG Run-qiuPEI Xiang-junZHAO Song-jiang
