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From China:Progress has been made in damage evolution of salt rock under cyclic loading with varying amplitude

Energy is an important material basis for human survival and support of social civilization and progress, but also the lifeblood of economic development. Oil and gas reserves are key to seasonal peak regulation, emergency supply and national energy security. Salt rock has good rheological properties, low permeability and self-recovery of damage, and is widely used for underground energy storage (natural gas, oil, compressed air, hydrogen, helium, etc.) and waste geological treatment. In the long-term operation of underground salt caverns, the creep of salt rock will cause continuous shrinkage and surface subsidence.

Yang Chun, a researcher at the Oil and Gas Center of Institute of Rock and Soil Mechanics, Chinese Academy of Sciences, and his team are committed to the study of underground energy reserves. Based on the theory of continuous damage mechanics, the damage evolution model of salt rock under cyclic loading with constant stress interval is established. Acoustic emission monitoring and CT scanning were used to evaluate damage and study fracture distribution. The results show that under cyclic loading with stress interval, the damage evolution of salt rock can be divided into three stages: initial, constant and accelerated. The relative variation of strain energy density can be used to quantify the damage change of salt rock during cyclic loading. The fracture distribution of salt rock after cyclic loading with stress interval is several main fractures and some micro fractures. This study provides important reference for the construction of natural gas storage and compressed air energy storage power stations in Jintan and Huai ‘an in Jiangsu, Qianjiang and Yingcheng in Hubei, Tai ‘an in Shandong and Ningjin in Hebei.

Related research results have been published in Rock Mechanics and Rock Engineering, Journal of Petroleum Science and Engineering, Engineering Fracture Mechanics, etc. The research work has been supported by the Science Fund for Outstanding Young Scholars, the National Natural Science Foundation of China, the Strategic Leading Science and Technology Project of CAS (Class B) and the Strategic Leading Science and Technology Project of CAS (Class C).

Links to papers: 1, 2, 3& NBSP;

FIG. 1. Stress-strain curve of salt rock under variable amplitude cyclic load with stress interval

FIG. 2. Damage evolution curve of salt rock under variable amplitude cyclic load with stress interval

FIG. 3. Fracture distribution at different sections of salt rock under variable amplitude cyclic load with stress intervals

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