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| Study on determination of uniaxial characteristic stress of coal rock under quasi-static strain rate |
| LIU Xiaohui1，2，HAO Qijun2，HU Ankui1，2，ZHENG Yu2 |
| (1. Key Laboratory of Fluid and Power Machinery of Ministry of Education，Xihua University，Chengdu，Sichuan 610039，China；2. School of Energy and Power Engineering，Xihua University，Chengdu，Sichuan 610039，China) |
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Abstract Based on uniaxial compression tests of Furong Baijiao coal rock under quasi-static strain rate[10－5，10－2] s－1，the energy evolution law of coal rock deformation and failure process under different strain rates was analyzed. A new method for determining the characteristic stress of coal rock by using energy dissipation rate curve and lateral strain difference was proposed，and the variation law of the characteristic stress under the category of quasi-static strain was analyzed. The results show that the energy evolution of coal rock under different strain rates can be divided into three stages including crack closure，linear elasticity and rapid crack propagation，and the energy dissipation rate curves all show a trend of rising first，then falling and next rising in the pre-peak stage. The maximum and the minimum points of the energy dissipation rate curves are respectively defined as the crack closure stress and the damage stress ，and the lateral strain difference is calculated to determine the crack initiation stress combined with the obtained damage stress. The ratios of the characteristic stress to the peak stress of coal rock under different strain rates are compared，showing that all three ratios decrease with increasing the strain rate. Finally，the limitation of the traditional methods and the rationality and accuracy of the new method are compared and analyzed，and the engineering significance of the strain rate effect of the characteristic stress is proposed.
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2020, Vol. 39 
