Study On The Stress And Deformation Characteristics Of Surrounding Rock Of Underground Cavern For Compressed Air Energy Storage

Compressed air energy storage power station is a kind of technology which uses compressed air to store energy on a large scale.The compressed air energy storage power station with manual excavation in hard rock has a good application prospect in the field of energy storage,which has many advantages such as wide adaptability of site selection,excellent ability of power load control and economic safety and reliability.In this paper,first of all,taking the pilot project which is the experiment carried out in Pingjiang Hunan province of compressed air energy storage as the research object.According to the structure of the air storage and the geological conditions,the three-dimensional numerical model was established to study the stress and deformation characteristics of the air storage under the single test condition.On this basis,a three-dimensional numerical model of air storage is established against the background of a large compressed air storage power station to expand and study the stress and deformation characteristics of surrounding rocks of large air storage under two different layout schemes.The main results are as follows:1.Through experiment,the thermal physical parameters of surrounding rock of Pingjiang underground compressed air energy storage are obtained.The specific heat capacity value is 0.707 KJ/Kg·K,the thermal conductivity value is 3.08 W/m·K,and the thermal expansion coefficient is 4.35×10-6/℃.2.Under a single test condition,the lining temperature changes are more obvious,and the surrounding rock temperature is relatively stable.The process of displacement change is compatible with each stage of the change of air pressure in the air storage cavern during the test.The closer the distance from the air storage cavern is,the larger the displacement change range is.The displacement change process within 3.35m of the air storage cavern is obvious.The maximum compressive stress of concrete lining is about 8.83MPa,the maximum tensile stress is about 1.80MPa.The maximum compressive stress of surrounding rock is about 7.55MPa,the maximum tensile stress is about 1.60MPa.The maximum radial displacement is about 0.23mm.Because of the stress and deformation in the acceptable range,the surrounding rock of Pingjiang air storage has good safety and stability.3.Under maximum operating pressure,the first principal stress of the large underground air storage plug area gradually decreases along the length of the plug,and the tensioned area is distributed at the joint between the front end of the plug and the lining connection.The maximum displacement direction of the plug area is consistent with the direction of being pushed away from the air storage.The displacement of the concrete plug in the plug area is greater than the displacement of the surrounding rock.The distribution of the first principal stress of the surrounding rock in the air storage area is that the farther the distance is from the wall,the smaller the stress value is.The distribution of the tensile stress of the third principal stress is that the tensile stress area of the surrounding rock at the top of the cavern is larger than that of the bottom and lateral surrounding rock.The regularity is that the farther away from the cavern wall,the smaller the displacement.4.The displacement of surrounding rock between large underground air storage caverns is larger than side of it.When the single-sided loading is applied,the displacement of surrounding rock is greater than that of double-sided loading.The surrounding rock of the plug area between the caverns is affected by this displacement.The influence is not conducive to the stability of the surrounding rock.The plug area at the end of the cavern is not affected by this factor,and the displacement of the surrounding rock in the plug area is small,which is beneficial to the stability of the surrounding rock.Therefore,the stability of the plug at the end of the cavern’s scheme is better than that of the plug in the middle.Combining the length of the traffic tunnel and the construction period to economically compare the two schemes,the economic efficiency of the plug in the middle between the caverns’ scheme is better than the plug at the end of the cavern.