Experimental Study On Unsaturated Seepage Flow In Fracture And Numerical Analysis Of Seepage Flow In Fractured Rock Mass Due To Surface Infiltration

In the doctoral dissertation, thorough studies on determination of unsaturated hydraulic parameters of fracture through experiment and numerical simulation, mechanisms of unsaturated seepage flow in fracture, analysis of saturated-unsaturated seepage flow in fractured rock mass due to surface infiltration and influence of surface infiltration to the stability of rock slope are made. And the above mentioned research achievements are applied to the analysis of real large-scale project. The main aspects of the subject are as follows:(I)Proceeded from the research of unsaturated seepage flow in fracture and the analysis models of unsaturated seepage flow in fractured rock mass, the research situation of unsaturated seepage flow in fractured rock mass is systematically reviewed. The general research situation of rock slope stability under the influence of surface infiltration is presented. Based on the analysis of the shortcomings of the existing research achievements, some problems needing to be researched furtherly are raised.(2)Used the predecessors' research achievements for reference, an experimental provision by which relationship between capillaiy pressure and saturation and relationship between unsaturated permeability and capillary pressure of fracture can be determined simultaneously is developed for the first time. Experiment of simplified fracture model on the provision is done. Mechanisms of unsaturated seepage flow in fracture are expounded initially and an experimental method to determine the unsaturated hydraulic parameters of fracture by using the provision is posed, which make it possible to determine the unsaturated hydraulic parameters of fracture through experiment(3)Based on the suming-up analysis of the advantages and disadvantages of the formerly numerical simulation methods, a more reasonable numerical simulation method to determine the unsaturated hydraulic parameters of fracture is posed by using fractal geometry and Monte-Carlo simulation. And relevant simulation program is also developed. Due to the effect of uentrapment of water and air is considered during the generation of water-filled cells, the method presented here can simulate the objective existing hysteresis between drainage and imbibition process, which can' t be reflected by the previous numerical simulation methods.(4) Aimed at rock mass with large fracture density, which can be equivalent to continuum, a mathematical model for saturated-unsaturated seepage flow in fractured rock mass due to surface infiltration is established. Galerkin finite element method is used as numerical simulation means and a finite element program used to calculate saturated-unsaturated seepage flow due to surface infiltration is worked out It is showed that the mathematical model and the program in this dissertation are reasonable and feasible through the analysis of some numerical examples.(5) Introduced the shear strength theory of unsaturated~oil, program for checking the stability of rock slope under the influence of surface infiltration is worked out by using the limit equilibrium method. Due to the contribution of matrix suction to the shear strength of rock mass and the harmful function of temporary additional water load are considered, the checking computation result of the above mentioned method conforms to reality better than those of the previous methods.(6) The above mentioned research achievements are applied to rainfall infiltration analysis of cushion pooi slope of Xiaowan power plant, atomized rain infiltration analysis of cushion pool slope of Xiluodu power plant and influence of surface infiltration to the stability of cushion pool slope of Xiluodu power plant. The results show that surface infiltration will bring harmful influence to the stability of slope and the model and program in this dissertation are reasonable and reliable.