Model Test And Calculation Analysis Of Excavation And Support Of Underground Laboratory For Geological Disposal Of High-level Radioactive Waste

With the development of energy industry in the world today,nuclear energy,as a kind of high quality clean energy,is increasingly recognized as an economic and effective measure to mitigate the world energy crisis.Deep-buried geological disposal of high-level radioactive waste has been accepted by more and more countries,and has proved to be technically feasible and economically reasonable.The construction of geological repository for high-level radioactive waste(HLW)is facing enormous challenges,which requires a high level of safety and reliability of its underground structure.These characteristics determine that it is very difficult in engineering construction and long-term operation safety.The underground laboratory for geological disposal of high-level radioactive waste needs to be established before the construction of the geological disposal repository of high-level radioactive waste.It can be used to understand the deep geological environment and in-situ stress conditions,and provide basic scientific research data and theoretical and practical experience for the construction of the repository.As a key facility and early stage project of geological disposal of high-level radioactive waste,underground laboratory is indispensable and extremely important.It is very important to study the surrounding rock stability and overall safety during the construction and excavation of underground laboratory caverns.The structure of underground laboratory caverns group is complex and there are many intersecting caverns.It is difficult to fully reflect the influence of surrounding rock excavated by caverns group construction only by theoretical analysis and numerical analysis.Based on the construction of underground laboratory of Beishan High-level Radioactive Waste Geological Disposal repository in Gansu Province,this paper carries out the three-dimensional geomechanical model test of similar simulation of excavation and support of underground laboratory of high-level radioactive waste geological disposal,optimizes the construction scheme of underground laboratory,and provides reasonable suggestions for the construction of underground laboratory.The results of this study are as follows:(1)Taking the construction of underground laboratory of high-level radioactive waste repository as background,according to the physical and mechanical parameters of surrounding rock media of Beishan granite:in Gansu Province,material proportioning and Laboratory mechanical tests are carried out,and similar materials of surrounding rock and bolt which basically meet the similar requirements of rock properties of Beishan granite are developed.(2)According to the design and excavation conditions of underground laboratory.three-dimensional geomechanical model tests of underground laboratory caverns in high-level radioactive waste disposal repository were carried out by using the developed similar materials and ultra-high pressure true three-dimensional loading model test system.The variation rules of displacement field and stress field of surrounding rock during excavation were effectively obtained,and the disturbance range of cavern excavation and the interaction rules of cavern group excavation were obtained.Law provides guidance for the construction of underground laboratories.(3)The whole overload model test was carried out in underground laboratory after step excavation.The deformation,failure pattern and failure process of surrounding rock during loading were observed,and the overload failure law and overload safety factor were obtained.(4)According to the excavation conditions of underground laboratory parking lot I,parking lot II and main roadway model test,numerical simulation is used to calculate and analyze the displacement and stress changes during the excavation of underground laboratory caverns.The numerical analysis results of the same monitoring location are basically consistent with the experimental results.(5)Through strength reduction method,the stability of surrounding rocks of excavated caverns is numerically simulated and analyzed.The displacement field and plastic zone of the caverns are obtained,and the safety factor obtained from overloading test is compared with that obtained from overloading test.