Comprehensive Evaluation Of Statistical Homogeneity Of Fractured Rock Mass On The Left Bank Of Wudongde Hydropower Station

Wudongde Hydropower Station is located at the border of Huidong County of Sichuan Province and Luquan County of Yunnan Province.It is the uppermost level of four hydropower cascades planned for the lower reaches of Jinsha River Hydropower Base.It has many benefits,such as power generation,flood control and shipping.The dam abutment and power plant of Wudongde Hydropower station are located in the mountains on both sides of Jinsha River.The strength and stability of rock mass on both sides directly affect the construction and operation safety of hydropower station.The rock mass involved in this project has a wide distribution range and a large volume,so it is a necessary prerequisite to carry out the homogeneity evaluation of rock mass and then to divide the statistical homogeneity zone to study the mechanical properties of rock mass in this region.In this paper,the fractured rock mass on the left bank of Wudongde Hydropower Station is taken as the research object,and the statistical homogeneity of rock mass in the region is studied based on the data of Pingdong exploration,and the fracture parameters revealed by PD42,PD44,PD46 and PD76 of Pingdong are selected as the statistical homogeneity research data.Firstly,the fracture data of the selected flat cave were sorted out,and the occurrence and trace length parameters of the fractures were statistically analyzed.Then,the occurrence data were divided by the stereographic projection method and Miller partitioning method,and the statistical homogeneity among the four groups of flat holes was analyzed by chi-square test of contingency table,correlation coefficient method and histogram intersection method.Then the fractal characteristics of the left bank rock mass are judged by the measured fracture trace map combined with the box counting dimension.Finally,for the trace length data,the minimum exposed trace length is 0.067 m and the longest is 7.36 m.Therefore,0.5 m is selected as an interval to divide the statistical trace length distribution histogram.The Chi-square test,correlation coefficient method and Wilcoxon rank sum test are combined to evaluate the similarity of trace length distribution.The results showed that when the occurrence was used as a parameter,the chi-square test showed that PD42 and PD46 had the strongest correlation.The correlation coefficient method showed that PD42 and PD46 had the strongest correlation,while PD44 and PD76 had the weakest correlation.Histogram intersection method showed that PD42 and PD46 had the strongest correlation.When the trace length is taken as a parameter,the results of box counting dimension method show that the trace length distribution of rock mass in Pingdong area is fractal.Based on chi-square test of trace length distribution histogram,the results show that the trace length distribution between PD42 and PD46,PD44 and PD76 has high similarity.The results of the correlation coefficient method showed that the trace length distribution between PD42 and PD46,PD44 and PD76 had high similarity.The Wilcoxon rank sum test showed that PD44 and PD76 had the same trace length distribution.According to the results of the two parameters and various similarity judgment methods,the regions of PD42 and PD46,PD44 and PD76 respectively have statistical homogeneity and can be divided into a statistical homogeneity region.