Experimental Study And Numerical Simulation On Hydraulic Of Fracturing Of Rock Mass

The hydraulic fracturing of rock mass is one embranchment of the fissured rock mass seepage-stress coupling research. The nucleus of hydraulic fracturing is mechanical effect and structural change of rock mass under high water pressure action. Along with the development of society, more and more geotechnical engineering such as construction of hydropower project, exploitation of oil and gas, deposition of nuclear waste, development of terrestrial heat and so on is in the high hydraulic head and deep embedded geohydrological condition, so that the hydraulic fracturing of rock mass is paid more and more attentions. Because of the complexity of the hydraulic fracturing of rock mass, up to now, the mechanism, the condition, the development and the criterion to the judging of hydraulic fracturing are still not manifest. This paper studies the hydraulic fracturing of rock mass with experiment and numerical simulation. And the research achievements are applied to the analysis of real project. The main aspects and achievements of this thesis are summarized as follows:(1) The related information and current research development about hydraulic fracturing of rock mass are summarized and studied, then based it, research target are brought up. The thoughtways and methods of other man are used for reference, the research method is established with experiment and academic analyse.(2) The samples for experiment of hydraulic fracturing of rock are designed. By the measurement test about material mechanics parameter of the cement mortar, compressive strength, tensile strength, elastic modulus, Poisson's ratio and stress-strain diagram of the cement mortar are obtained, which provide the basis of the characterization of the test sample used in hydraulic fracturing test.(3) The method of hydraulic fracturing experiment is decided with rock mass substituted by cement mortar. Hydraulic fracturing tests of thick-wall cylinder sample are performed with the kind of experiments is nine and the number of sample is about to thirty. The failure form of the sample, the relationship between pressure conducing hydraulic fracturing and stress state of the sample and the influence of pore water pressure, confining pressure, inside diameter of the sample and loading course to hydraulic fracturing are obtained by analyzed the test results.(4) The presetting crack elements are presented by introduced the dummy contact surface element. Based on the theory of elastic brittle mechanics, a numerical simulation means of invariable mesh and a finite element program used to calculate 3D hydraulic fracturing of rock mass are worked out. It is showed that the mathematical model and the program in this thesis are corrected through the comparison of the test results and simulation results.(5) The above mentioned research achievements are applied to hydraulic fracturing analysis of liner of water tunnel in pumped-storage hydroplant at black dragon mountain. The appraisement about the security and stability and the suggestion of the water tunnel are brought up, which provide the foundation for devise and construction of this engineering.(6) Aimed at the shortages of the study in this thesis, question was pointed out and prospected.