Experimental Investigation And Theoretical Analysis Of Rock Salt Creep

Rock salt has good waterproof property and airtightness, mechanical property is stable. These make it the perfect medium to build chamber cavern. China is turning into a large-scale construction period of salt cavern energy storage. It is necessary to study the creep property of rock salt on different view, research the salt caves’ stability in a long period. Through traditional indoor rock mechanics testing, theoretical analysis and computer simulation, this paper research the creep property of rock salt from different views and conditions and its mechanism.①Through systematic rock salt compression tests, the paper got the mechanical parameter of rock salt. Study the mechanical property in different stress conditions and loading rates. The mechanical property of rock salt is stable in this region, has less discreteness, ultimate strength which got by different tests is basically the same value. By analyze the AE phenomenon, It is found that AE counts maximum at the biggest press stage, AE phenomenon is not obvious in the early stage, the higher the strain rates are, the bigger the AE counts per unit time are, the smaller the accumulated AE counts are. There is no AE phenomenon in the early stage when the strain rates is slow. Use fractal theory to analyze the correlation dimension in AE phenomenon. CD shows a rising trend at first, gets peak value before the specimen broken, Through analyze correlation dimension, it can get the harbinger information of rock salt broken.②Through uniaxial and triaxial creep test, analyze axial stress and confining pressure effect on rock salt creep, It is found the rock salts which consist of big grain crystal have big strain after creep tests. Rock salts have good ductility. With constant confining pressure, increase the axial stress, creep develops faster, the steady-state creep strain rate increases, the time taken by the whole creep decreases. On the whole, confining pressure can reduce the creep rates, generate accelerated creep stage deficiency.③The paper sets up the creep constitutive model with damage, constitutive model simulates the accelerated creep stage well. Use Matlab fit parameters, the computational curves are conform with the test results.④Set up rock salt cave model, the paper studies the stability of rock salt cave in a long period by FLAC 3D, analyzes the impact of the running pressure value on cavity’s stability. Increase the operation pressure within the limits of ultimate pressure can improve the stability of rock salt cave. Calculate the biggest cavity creep value and shrinking percentage, judge the security of rock salt under limitation press. The paper figures out the safety factor of salt cavity and the safety width among cavities.