A Quantitative Analysis Of Rock Mass Structures And Evaluation Of The Blocks' Stability

Detailed field surveys have been carrided out in Ludila water-power staion, which is located on Jinsha -River, for this paper. Making the better of plenty of datas gained from surface survey and prospecting adit, a research on underground cavities is started from the damsite's geological setting. Then structures of rock mass, surrounding rockmass classification, stability of the local blocks, deformation in whole cavities and so on have been outspread in order to evaluate the underground cavitie' stabiliy. Linked with this engineering, some problems or shortages in the study of the general underground cavities' stability have been pointed out. Then some method have been put forward to mend and perfect the study on underground cavities' stability.In the study of the structures of rock mass, a linear equation between Joint's trace and its width has been set up, through the particular statistic on a large range of rock outcrops in the routes into the dam-site and prospecting adits. The real trace of the joint in limited outcrops in the prospecting adits can be calculate use its width. By introducing the density of joint traces into the structure classification, the rock mass structures of the underground cavities' surrounding rocks in Ludila hydropower station have been classified according to its space between dominant joints and its density of joint traces respectively. Taking the density of joint traces as a basic quantitative index, the density degree of the joints exhibited in the prospecting adits' wall has been studied depending on the moving avergage method. Then the distributing characteristic of rock mass structures is described quantificationally by a isopycnic map. Linking the mechanics test of fault clay with the current Code, the standard value of structure planes in different types ,which are exposured by the prospecting adits, has been discussed briefly.In the study of engineering geologic classification of surrounding rock mass, the values of several dominating classification indexes are discussed. Shortages of the RQD gained by measuring line in current engineering are analyzed. A method of RQD computing by the density of joint traces in the wall's of prospecting adits is put forward here, then it is contrasted with the RQD gained by measuring line. By sound wave testing in PD8-1 prospecting adit, intactness indexes of rock mass in every cells are obtained. Depending on the relationships between intactness indexes of rock mass...