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为解决采用应变片对超临界CO_2作用下煤体膨胀变形进行点测量时,试验结果离散性大、超临界CO_2作用导致应变片易脱离破损等问题,自主研发了具有施加热流力载荷功能的膨胀体积应变测量装置,对不同温度、压力的超临界CO_2作用下,煤体膨胀体积变形规律进行研究。结果表明:煤体膨胀体积应变随超临界CO_2作用时间增加呈现先增大后趋于稳定的变化规律;当孔隙压力不变时,膨胀体积应变随超临界温度的升高而增加,温度越高,达到稳定膨胀变形所需时间越长;当温度不变时,随着超临界孔隙压力增加,膨胀体积应变也随之增大,但达到稳定膨胀变形所需时间随孔隙压力的升高呈先增加后减少的趋势;超临界CO_2作用下,煤体体积应变随温度和孔隙压力均呈“S型”Logistic函数规律变化;膨胀体积应变对超临界温度和孔隙压力的变化率具有分区性,其变化率大小排序依次为:近临界区>跨临界区>高临界区。
In order to solve the problem that the strain gauge is used to measure the expansion and deformation of coal under the action of supercritical CO_2, the test results are large in discreteness and easy to break away from the damaged gauge by supercritical CO_2. Volumetric strain measurement device, under different temperatures and pressures of supercritical CO_2, the expansion of the volume of coal deformation law. The results show that the volumetric strain of coal expands with the increase of supercritical CO_2 first and then tends to be stable. When the pore pressure is constant, the volumetric strain of expanded coal increases with the increase of supercritical temperature, and the higher the temperature, , The longer time it takes to reach stable expansion and deformation; when the temperature is constant, the volumetric strain of expansion also increases with the increase of supercritical pore pressure, but the time required to reach steady expansion increases first with the increase of pore pressure The trend of volumetric strain changes with the change of temperature and pore pressure under the action of supercritical CO_2. The change of volumetric strain of supercritical temperature and pore pressure is proportional to the change of logistic function. The order of the rate of change is as follows: near-critical area> trans-critical area> high-critical area.