A Open Pit Mine In Yunnan East Mining District Of Rock Mechanical Parameters Value

Because rock mass possesses heterogeneity, discontinuity,uncertainty and along with the time variation characteristic. How to decide reasonable value of the rock mass mechanics parameter is one of the most puzzled bottleneck question for Geomechanieal researchers. Nowadays many theories in rock mass mechanics research, such as slope stability analytic method, rock ground theory and granular material consolidation theory, are perfect.Only the rock mass (rock joints) mechanics parameter determination falls behind practice.The difference between calculation result and practical result is because of rock mass mechanics parameter. The research on how to decide the rock mass mechanics parameter is the most basic and important work.This article has carried on initial exploration and research in view of the current research difficulty of rock mass mechanical parameter, and the research result will be applied to actual slope project. The slope stability analysis take its rock and soil mass mechanical parameter to determine as the premise.this paper take in-situ direct shear test of slope rock mass of an open-pit mine in Yunnan as object of study. First, according to the mechanical test result of the laboratory, the quality evaluation results RMR of rock mass which is combined with scene geological surveys are obtained, by the empirical formula of Hoek-Borwn method to determine the rock mass shear strength parameter; Then based on shear test data that is obtained by in-situ direct shear test, according to reliability method, least squares method, random-fuzzy method and so on, each main rock mass shear strength parameter that conforms to the actual scene is obtain; Next through contrast between experience estimate-method and direct shear test method, the difference is examined between computation result of experience estimate-method and computation result of direct shear test results. Through analysis of comparison between the results, whether experience estimate-method (Hoek-Borwn method) can replace in-situ direct shear test,so that experience estimate-method play well an effect in predicting rock mass shear strength parameter.Finally, by above the two methods to determine the mechanical parameters of rock mass, three-dimensional numerical model of rock slope is established, then geotechnical engineering analysis software FLAC3D is used to carry on slope stability analysis. By the degree of the simulation result coinciding with the scene situation to carry on the project examination, rationality and reliability of rock mass mechanical parameter to determined are analyzed and verified. The comparative analysis of parameters and field engineering test show that:Ⅰ) Calculation result of reliability method is superior to least squares method and random-fuzzy method. Consideration from the reliability point of view, this method is more representative in theory.Ⅱ) When the test condition is not permitted, or by means of in-situ direct shear test the parameter of hard rock mass is determined under very difficult condition,The experience estimate-method can substitute the in-situ direct shear test method to determine the rock mass mechanical parameter. The results show that the method which is proposed in this article has certain feasibility.It is a feasible and effective method to determine reasonably the rock mass shear strength parameter.