(1. College of Geological Engineering and Surveying，Chang¢an University，Xi'an，Shaanxi 710054，China；2. Field Observation and Research Station of Water Cycle and Geological Environment of Ministry of Education of the Loess Plateau，Qingyang，Gansu 745399，China；3. China Coal Xi'an Design Engineering Co.，Ltd.，Xi'an，Shaanxi 710000，China)
Abstract：The roughness of joints in rock mass is very important for the calculation of the shear strength. However，the determination of JRC(joint roughness coefficient) based on the 10 standard curves established by Barton is often subjective and uncertain，so it is important theoretical significance and practical application values to do further study about this issue. In this paper，all the standard joint roughness curves by Barton are quantized. The length of the datum line L0 is selected as 10 cm and the contour length L of each curve is measured. The functional relationship between the section length ratio of the contour length to the datum line length L/L0 and JRC can be fitted. Based on the ellipse definition and the sine function method，the curves are redistributed according to their contour lengths，and the maximum undulation Ry1 and Ry2 under two extreme distribution states are obtained. Making the maximum undulations correspond to the upper and lower limits of JRC，then，the functional relationship between Ry and JRC can be fitted. Finally，by bivariate fitting of the above two functional relationships，the functional relationship between JRC with L/L0 and Ry is obtained with a fit goodness of 99.24%. Taking the discontinuities of the slopes in Heihe reservoir area and Zhen¢an County of Xi¢an city as the cases，comparison between the developed approach with the classical JRC calculation method is performed. It is found that the calculation results are similar while the change trend of the JRC value calculated by the proposed function is more stable than the classical method，verifying the feasibility of the developed method.
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2021, Vol. 40 
