Study On Washing Process Of Rock-Salt Cavern With Coupled Stress-Dissolving Mechanism

Security, depositing energy sources and disposing nuclear waste in rock salt, is principle question. Aiming at shape controlling and stability of salt cavern, many researchers make fruitful studying works, but much shortage and questions exist and must study and analysis further. During the course of actual washing process of salt cavern, stress effect and dissolving effect must take into account. Coupling stress-dissolving effect makes important influence in shape controlling and stability during the course of washing process of salt cavern, but salt cavern mechanism with coupled stress-dissolving effect and studied way hasn't been solved primly. It is international advancing subject on studying rock salt mechanism also. Aiming at above problems, this paper analyze the experiment outcome of rock salt uniaxial compression meso-mechanics test considering coupled stress-dissolving effect, variation of rock salt dissolving action under effect of stress and variation of rock salt mechanism under effect of dissolving, and on the basis of above research, rock salt cavern mechanism with coupled stress-dissolving effect has been studied, and washing process of salt cavern with coupled stress-dissolving effect has been simulated and computed. Through above study and analysis, some conclusions have been obtained.1. First of all, through rock salt uniaxial compression meso-mechanics test considering coupled stress-dissolving effect, difference of rock salt dissolving speed between considering stress effect and not, and variation of rock salt mechanism with dissolving effect has been proofed; And then, through analyzing results of experiments, variation rule of rock salt dissolving speed taking account of effect of stress and computing formula between dissolving mass and axial plastic strain and dissolving time has been concluded, under effect of stress relationship between dissolving mass and development and expansion of crack has been founded, variation of dissolving mass can be explained by different phase of development and expansion of crack; Through test, variation rule of rock salt mechanics taking account of dissolving effect and computing formula between decreasing ratio of stress and dissolving mass of different axial plastic strain and different time has been concluded, and through analyzing comparison between critical stress intensity factor and stress intensity factor of crack on mechanism, on the phase of dissolving, the reason of decreasing of stress with time increasing has been studied.2. Selecting strain harding-softing model, rock salt elasto-plastic mechanics model not considering solution effect has been building, and through rock salt triaxial compression test, relationship between cohesion, internal friction angle and equivalent plastic strain has been solved; taking account of solution effect or not, rock salt damage mechanism is same approximatively, the mechanism of variation of rock salt mechanics taking account of solution effect is critical stress intensity factor of crack decreasing because of dissolving, and cohesion and internal friction angle is changed; And then through analyzing experimental data of dissolving phase and reloading phase of rock salt uniaxial compression meso-mechanics test considering coupled stress-dissolving effect, rule of cohesion value in dissolving phase and reloading phase has been concluded by FLAC- Genetic Algorithms, and computing formula of cohesion value considering coupled stress-dissolving effect has been concluded; Through modeling rock salt uniaxial compression meso-mechanics test considering coupled stress-dissolving effect, rationality of cohesion value computing formula has been proofed; At last during the course of salt cavern building with water, it can be concluded that variation of mechanical parameters taking account of solution effect must be considered. 3. Through studying rock salt solution mechanism and computing of fluid transport and dissolving speed considered dissolving effect just, rock salt dissolving model not taking account of effect of stress has been building; And then, through phenomenon of dissolving test of surface crack of rock salt and coupled penetrating-dissolving test for single rock salt crack, difference of rock salt solution mechanism between taking account of stress and not has been proofed; On the basis of above study, equivalent coefficient of diffusion, is function with equivalent plastic strain and time, has been made, it's aim is describing macro-dissolving speed under unit area, and rock salt dissolving model with effect of stress has been building; And then through computing by compiling finite difference program, relationship between equivalent plastic strain, dissolving time and equivalent coefficient of diffusion is expressed; At last, it has been concluded that for rock salt solution effect, effect of stress is un-ignored.4. On the basis of above study and analyze, coupled stress-dissolving mechanism of rock-salt cavern has been studied; And washing process of salt cavern with coupled stress-dissolving effect has been simulated and computed; At last, through computing salt cavern by taking account of coupled stress-dissolving effect and by taking account of dissolving effect respectively, difference of outcome between two ways has been compared, the shape of rock-salt cavern with coupled stress-dissolving effect is more coincident to actual salt cavern shape than just considering dissolving.