Stability Analysis On Underground Caverns Of Lianghekou Hydroelectric Power Station

Lianghekou Hydropower Station is a controlling hydroelectric power station of the middle and low reaches of Yalong River., the whole cascade Yalong tremendous impact on the development of power plants.The Lianghekou Hydropower Station which is 3000MW-installed capacity, is planned to adopt the form of the underground factory, building, which is formed by three large cavities. The three main underground cavities were disposed parallelly and the axes direction is N3°E. As a whole the rock quality of the hill is well. But because of the tectonic movements and epigene-action, joints and faults, which reduce the hardness of the rock body, haveincised the rock body. Moreover, the cavities have excavated in big span and in groups, which resulted in the biggish adjust of the rock body stress and displacement,and this adjust maybe lead to destroy in rock mass. Thereby, the project can't go on or the cavities can't work normally.On basis of comprehensive analysis of plenty of in-situ investigations and former findings in Lianghekou, the author established complex rock mass model by description of rock mass conditions. Then following basic methods for evaluating the stability of underground cavern group's surrounding rock combining whole deformation with local blocks stability evaluation, the findings can be obtained as follows:(1)According to a lot of field work with measuring data and indoor statistical analysis,this paper has studied the engineering geological characteristic and classified the type of rock structure in the dam area.(2) After obtaining above-mentioned materials, synthetical classification has been figured out based on quantitative analysis and contrast synthesis.Also mechanics parameters for different rock types have been brought forward according to the synthetical analysis of field experiments data together with rock mass quality classification indexes.(3) Based on the conceptual model of rock mass structure in the engineering area, Flac3D is used to simulate stress, strain and plastic zone distribution and dynamic characteristics of the Surrounding rocks of underground cavern groups and diversion generating system after excavation with fundamental theories and methods of complex rock mass modeling. And engineering effects of controlled structure planes are analyzed and summarized in order to provide basic data and theory for evaluating systematically the stability and supporting designs of underground cavern groups and diversion generating system.(4) Based on the simplified geology structure, Stability of potential blocks at different constructional position surrounding rock mass is calculated and sensitivity to influencing factors of the blocks in surrounding rock mass is analyzed using software SASW.