A Method for Determining the Minimum Sample Size of Joints Based on Fisher Distribution of Orientation
The orientation of joints is one of the key parameters affecting the structure of rock mass and its engineering properties.Therefore,accurate calculation of the mean orientation of joints is the basis for the study of engineering properties of rock mass.Due to the dispersion of the joint orientation,it is of great significance to reasonably determine the minimum sample size of the joint for calculating the mean orientation of the joint group.Based on the Fisher distribution,this paper explains the generation method of random numbers for joint orientation,and proposes a calculation method for the mean orientation that considers the orientations extending beyond the edge of an upper hemisphere projection(OEBEUHP).To investigate the effect of joint sample size on the mean orientation accuracy,the empirical relationship between the minimum sample size and the κ value was established under the condition that the accuracy rate was not less than 0.95.The results show that the joint sample size has a significant impact on the statistical accuracy of the mean orientation.The larger the sample size,the higher the statistical accuracy of the mean occurrence.The minimum sample size has an obvious inverse proportional relationship with the κ value,and the inverse proportionality coefficient is 1 007.23.The applicability of this empirical relationship is verified through statistical research on the upstream side wall joints of the Three Gorges underground powerhouse and joints in the adit PD5-2 of the Wudongde hydropower station,which can provide effective guidance on the sampling of joint orientations.
国家科技期刊平台
NSTL
万方数据
维普
