Scale Effects And Sequential Indicator Simulation Of Hydraulic Conductivity In Basalt

Groundwater seepage in fractured rock is one of important science issues and engineering applications in water resources and hydropower engineering, civil engineering and geologic nuclear waste repository. Mathematical models of seepage in fractured rock can be classified into: continuum seepage model, discrete fracture network seepage model and continuum-discrete coupling seepage model. The last two models that can precisely characterize the true seepage in fractured rock develop very quickly, but they are only applied to the small scale area. As continuum seepage model regards fractured rock as porous media, many successful theories and solution methods on porous media can be used to study groundwater seepage in fractured rock. Continuum model is often used to simulate groundwater seepage in regional fractured rock, for example groundwater seepage in dam site.For continuum seepage model, the most important component is to build the hydraulic conductivity (K) field, which includes acquiring the K values by field measurements and determine K of all mesh grids in the model according to K values of finite field samples. There are many kinds of methods to acquire the K of fractured rock and every kind of measurement has itself applicability. Therefore, it is a challenge to choose appropriate measurement on the basis of the geological condition and precision of study object. Parameter zoning, interpolating and stochastic simulation are often used to determine the hydraulic conductivity of model. It is not reasonable to characterize the heterogeneity of fractured rock by parameter zoning and interpolating. It is the key and difficulty to choose right method to characterize the high heterogeneity of fractured rock media on the basis of range and precision of study object.Aiming at the above two difficulties, permeability of the basalt of Dam Area of Xiluodu Hydroelectrical Station across Jinshajiang River and Guandi hydroelectrical station across Yalongjiang River have been studied in this paper. The following works have been carried out: (1) Fractures in Emeishan basalt of Permian period in Xiluodu horizontal rockflow and Guandi vertical rockflow had been investigated in the field. (2) Hydraulic conductivity investigation methods of fractured rock in recent years were summarized in this paper. Field hydraulic tests, fracture measuring, flow numerical test method of discrete fracture network were often used to determine hydraulic conductivity. Each kind of investigation method had its applicability and test scale. 2715 water pressure tests in single borehole were carried out in 86 boreholes of dam area of Xiluodu and 1388 water pressure tests in 96 boreholes of dam area of Gaundi. As the geologic condition is very complex and multi-level scale fractures developed in the dam area of Xiluodu, groundwater tracer test and water seepage test in adits were used to investigate the permeability of basalt. (3) On the basis of water pressure tests, spatial variation of hydraulic conductivity have been analyzed. (4) Results of hydraulic tests with different measuring test...