[Objective]The aperture of fractures(hydraulic equivalent aperture of fractures)of rock fractures is one of the key mechanical parameters of rocks.It has significant indicative significance in water conservancy pro-jects,geological surveys and so on.At present,large-scale test methods such as cross-hole tests are often used to obtain the fracture apertures of deep rock masses in the field,but this method is rarely used many times in projects,and it is difficult to analyse the spatial variation in the aperture of fractures.This spatial variation is precisely what we need to focus on and discuss because it affects the accurate definition and application of the hydraulic equivalent fracture aperture in engineering applications.[Methods]In this paper,taking the surrounding rock of an under-ground power station cavern on the right bank of the Three Gorges Dam as an example,a new inversion method for determining the hydraulic equivalent aperture of fractures is proposed by using conventional single-hole water injec-tion test data and three-dimensional fracture network simulation.The statistical data obtained from the measured fracture cataloguing data are used to carry out random simulation of fracture characteristics,and a three-dimensional discrete fracture network seepage model connected with water injection test boreholes is constructed to fit the rela-tionship between the single-hole steady-state flow rate and injection.The hydraulic equivalent apertures of fractures at different depths of rocks are inverted.[Results]The results show that the hydraulic equivalent aperture of frac-tures in the research area is generally 0.07-0.30 mm,which confirms to the statistical characteristics of the log-normal distribution.Most of the inverted hydraulic equivalent apertures of fractures in boreholes decrease exponen-tially with burial depth,while a few boreholes show strong randomness of the hydraulic equivalent aperture of frac-tures and no obvious change with burial depth.[Conclusion]Compared to those of traditional methods,the inver-sion results of this approach are significantly different and require further verification.
关键词
裂隙岩体/裂隙张开度/离散裂隙网络模型/数值模拟/压水试验/三峡大坝
Key words
fracture rock mass/fractures aperture/discrete fracture network model/numerical simulation/water injection test/Three Gorges Dam
维普
万方数据