(1. College of Mining Engineering，Taiyuan University of Technology，Taiyuan，Shanxi 030024，China；2. Key Laboratory of
In-situ Property-improving Mining of Ministry of Education，Taiyuan University of Technology，Taiyuan，Shanxi 030024，China)
Abstract：In order to study the effects of loading strain rate and supercritical CO2 on the mechanical properties of coal rock，uniaxial compression experiments of un-soaked and supercritical CO2 soaked coal rock are carried out under different quasi-static strain rate(10－5，10－4，10－3，10－2 s－1) loading. The energy signals during the loading process are recorded by acoustic emission monitoring system. The uniaxial compressive strength，elastic modulus，failure mode，energy evolution and AE characteristic parameters of the tested coal rock are studied from the perspective of strain rate effect and ScCO2 soaking weakened mechanism. The results show that：(1) With the increase of the loading strain rate，the compressive strength and elastic modulus of the un-soaked and supercritical CO2-soaked coal rock increase at first and decrease later. Under the loading strain rates of 10－5 and 10－2 s－1，the deterioration of mechanical properties of coal soaked in supercritical CO2 is more obvious. The uniaxial compressive strength of coal rock is reduced by 28.66% and 34.98%，and the corresponding elastic modulus is reduced by 35.50% and 27.68%，respectively. (2) The failure mode of un-soaked supercritical CO2 coal rock is mainly in the style of the X-shaped conjugated shear failure，while the failure mode of the supercritical CO2 soaked coal rock changes from inclined shear failure to vertical splitting tensile failure with the loading rate increase. (3) Both the loading strain rate and ScCO2 have effects on the mechanical properties of coal and rock. They also affect the elastic strain energy stored in the tested coal rock. It can be proved from the measured acoustic emission signal which characterizes the energy release during the failure process of the coal rock. This study is not only meaningful for revealing the variation law of mechanical properties of the supercritical CO2-soaked coal rock under different loading rates，but also helpful for understanding the coal rock deformation and fracture characteristics during fracturing of coal reservoirs.
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2023, Vol. 42 
