Unequal interval sampling，vector representation and roughness of joint profile
CHEN Chong1，2，CHEN Shenghong1
(1. State Key Laboratory of Water Resources and Hydropower Engineering Science，Wuhan University，Wuhan，Hubei 430072，China；2. Key Laboratory of Geotechnical Mechanics and Engineering of the Ministry of Water Resources，Yangtze River Scientific Research Institute，Wuhan，Hubei 430010，China)
Abstract：The undulation and roughness of joint plane are important factors affecting mechanical parameters of rock mass. The existing statistical methods of joint profile roughness parameters usually adopt the equal interval sampling method，and there are deviations between the obtained sampling points and the turning points of joint profile fluctuation. In view of the fact that photographing and digital image processing technology are widely used in joint measurement，and pixel is the smallest unit of an image. A unequal interval sampling method based on describing the set of joint plane points is proposed，and then all adjacent sampling points are represented by vector. A new formula for calculating root mean square Z2 of the first derivative of joint profile is also proposed. The conclusions are as follows. (1) The sampling points of the unequal interval sampling method are located at the turning points of the structural surface fluctuation，which are in good agreement with the original contour. (2) Based on the vector representation of the joint profile，the deviations of the joint profile roughness parameters can be calculated quantitatively. (3) The unequal interval sampling and vector representation will make the process of roughness solution more accurate and faster.
2021, Vol. 40 
