Experimental Study On Characteristic Weights Of Discontinuity Surfaces In RMR

The geomechanical classification method(RMR method)is currently widely used rock mass classification method.However,the adjustment scores of various indicators in the evaluation system are rather vague,and the scores are subjective,often resulting in a large deviation in the final conclusion.Among them,the value of any combined level score for each parameter of the discontinuity surface index weighting sums up to 30% of the total value of the six main factors..Therefore,this paper focused on the non-continuous surface conditions.Because of the lack of uniform numerical criteria for the index values of the guidance parameters under the condition of non-continuous surface,this paper briefly discusses the weight of each parameter index value in the non-continuous surface condition.In this paper,the first systematic study of the theory,and then using experimental means,to characterize the roughness of the non-continuous surface characteristics of the quantitative study.Similar materials were studied for the three parameters of opening,filling and weathering in other related parameters.And because the experimental research in this paper is a small model test,the connectivity is not taken into account for the time being.Then,the shear strength test is used to obtain the rock strength parameters under the non-continuous surface condition.Finally,the weights of the index values of various parameters are analyzed by using the analytic hierarchy process.The main work and research results of this paper were as follows:(1)Discontinuous surface roughness quantitative test.The use of different particle sizes of quartz sand ratio to produce different degrees of roughness,through the laser scanning surface technology to obtain the roughness of the surface form of the coordinate data.Based on experimental variogram theory and Fractal Hurst exponent,the Matlab programming was used to calculate the fractal dimension which characterizes the roughness,and the experimental variogram was obtained.The range of fractal dimensions with different ratios was determined to realize the quantification of the roughness of the discontinuities,and it was used as the basis for the shear test of specimens with non-continuous surface characteristics.(2)Based on the site survey of Jinshandian iron ore,similarity theory was used to determine the similar materials that simulate the characteristics of the discontinuity surface and the materials containing the non-continuous surface rock specimens.The roughness material is made of natural quartz sand,and the degree of weathering material is made of highly weathered,moderately weathered and weathered rocks on the joint surface of Zhangfushan East.The filler used in the filling is natural quartz powder,and the soft filler is in the mining joints with soft filler.At the same time,uniaxial compression test was carried out to determine the proportion of rock specimens that Cement: gypsum: the sand is 1:0.04:4.3,the water ratio is 0.16.(3)Specimens with non-continuous surface properties were shear tested.Including single factor test,orthogonal test and blank test;Using Mohr's theory,draw the intensity envelope,stress-strain curve,time and load change curve to obtain the cohesive force c of the rock mass and the internal friction angle ? of the rock mass.Orthogonal test analysis was performed to determine the primary and secondary factors that affect the four parameters in the rock strength parameters.(4)Using the Analytic Hierarchy Process,the relative weights of the four factors and the relative weights of the factors corresponding to the five levels are calculated.The total scores of the four factors and their corresponding scores are re-determined.Table 6-11.And,the total score of each factor score are: openness 19 points,roughness 11 points,filling 10 points,and weathering is 20 points.