REV And Shear Strength Parameters Of Layered Fractured Rock Mass

The determination of shear strength parameters of layered fractured rock mass plays an important role in the stability evaluation and engineering design of geotechnical engineering.The rationality of its value has always been one of the hot and difficult problems in geotechnical engineering.Layered fractured rock mass has a large number of random structural planes,and its structural characteristics are complex,showing heterogeneity.Its mechanical parameters are affected by the size effect.Therefore,the study of the size effect(REV)of layered fractured rock mass is the key to determine the shear strength parameters of layered fractured rock mass.At present,there is little research on the size effect of layered fractured rock mass.In this paper,taking the layered fractured rock mass of actual cutting slope engineering as an example,the mechanical parameters of rock block and structural plane are obtained by laboratory test,the two-dimensional network model of structural plane of layered fractured rock mass is established,and the REV value of layered fractured rock mass is determined.Based on this,the shear strength parameters of layered fractured rock mass are obtained by numerical simulation calculation,and are verified with the results of field drilling shear test.The research results are as follows :(1)Using the method of rock mass structural plane simulation,the mathematical method is used to characterize the rock mass structural plane in the form of ’ endpoint+ line ’ in the two-dimensional plane,and the Monte-Carlo method is used to simulate the structural plane of layered fractured rock mass,and the two-dimensional network model is established.(2)The fractal dimension is used to characterize the REV of rock mass structure.The results show that the fractal dimension of rock mass structural plane distribution changes with the change of model size,and gradually tends to a certain value,which can be used as the rock mass structure REV of layered fractured rock mass.(3)The size effect(REV)of deformation and mechanical parameters of layered fractured rock mass was studied by RFPA2 D numerical analysis software.The results show that the uniaxial compressive strength,tensile strength and elastic modulus of rock mass model tend to a certain value with the increase of its size,which can be used as the mechanical parameter REV of layered fractured rock mass.It has good consistency with the REV of rock mass structure determined by fractal dimension,and the REV value of layered fractured rock mass of cutting slope of Sanqing Expressway is obtained by comprehensive analysis.(4)According to the REV value of layered fractured rock mass,the shear strength parameters of layered fractured rock mass are determined by numerical test method,and the obtained shear strength parameters are in good agreement with the results of field drilling shear test.