STUDY OF RELATIONSHIP BETWEEN JOINT ROUGHNESS COEFFICIENT AND STATISTICAL PARAMETERS
WU Yuexiu1，LIU Quansheng1，2，LIU Xiaoyan1
(1. Key Laboratory of Rock Mechanics in Hydraulic Structural Engineering of Ministry of Education，Wuhan University，Wuhan，Hubei 430072，China；2. State Key Laboratory of Geomechanics and Geotechnical Engineering，Institute of Rock and Soil Mechanics，Chinese Academy of Sciences，Wuhan，Hubei 430071，China)
Abstract：The previous methods for measuring joint roughness coefficient JRC are based on ten standard joint profiles，their errors are large and are disturbed by human factor. Besides，the effects of sample size which is used to scatter the rough joint profile on JRC and statistical parameters are not considered. In order to avoid the measurement error of JRC of ten standard joint profiles，size，the study is conducted from the perspective of numerical simulation of rough joint by considering the range of JRC and the effect of sample. Joint projection height is assumed to accord with the truncated normal distribution；the projection profile of joint is generated with the projection height and sample size of each segment；and rough joint with a certain trace is generated finally. According to Barton′s straight edge method，JRC is measured. Each statistical parameter is calculated；and the relationships between JRC and statistical parameters are fitted with different sample sizes. The results show that：the regression functions between JRC and RMS，CLA are linear，the regression functions between JRC and MSV，Z2，Rp，SF are exponential and the related coefficients are very large. The effect of sample size on results is significant；and it is advised that sample size should be close to the particle size of rock mass. Because that MSV，RMS and CLA can only reflect the average value of projection height of rough joint，while they cannot reflect the effect of weights of various projection heights on JRC. Therefore，it is suggested that Z2 and SF should be adopted to evaluate the value of JRC.
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2011, Vol. 30 
