温度循环及渗透压对单裂隙花岗岩裂隙开度影响的实验研究

Experimental study on the influence of temperature cycle and osmotic pressure on the fracture opening of single-fracture granite

在干热岩地热开采中,花岗岩裂隙的演化对热能提取起着至关重要的作用。为了探讨循环高温下花岗岩裂隙开度的演化规律,采用多功能高温三轴伺服控制试验机,对温度为100~300℃的高温单裂隙花岗岩进行渗流实验,研究了不同温度、温度循环(次数为10次)及渗透压力对花岗岩裂隙开度的影响。研究结果表明:①无论温度多高,裂隙开度随渗透压的增加呈增大趋势,但温度不同,裂隙开度随渗透压增加而增大幅度不同,存在明显的转折点,温度不同,转折点不同;②无论渗透压多高,裂隙开度都随温度的升高而降低,但降低的幅度与温度有关;③无论循环温度多高,在同一渗透压下,起初的数次温度循环中,裂隙开度是降低的,当循环次数逐渐增加,裂隙开度也增大,温度越高其增大的趋势越明显。实验结果可为今后控制花岗岩裂隙演化的深入研究提供基础的实验数据。

In the hot dry rock geothermal mining,the evolution of granite fissures is very important for heat energy extraction.In order to explore the evolution law of granite fracture opening under cyclic high temperature,the seepage experiment of high-temperature single fracture granite with temperature of 100-300℃is carried out by using multi-functional high-temperature triaxial servo control testing machine.The effects of different temperatures,temperature cycles(10 times)and seepage pressure on granite fracture opening are studied.The results show that no matter how high the temperature is,the fracture opening tends to increase with the increase of osmotic pressure,but the fracture opening increases with the increase of osmotic pressure at different temperatures,and there is an obvious turning point.When temperature is different,the turning point is different.No matter how high the osmotic pressure is,the fracture opening decreases with the increase of temperature,but the degree of decrease is related to the temperature.For the first few temperature cycles at the same osmotic pressure,no matter how high the cycle temperature is,the fracture opening decreases.When the number of cycles gradually increases,the fracture opening also increases.The higher the temperature,the more obvious the tendency of increase.The experimental results can provide basic experimental data for the in-depth study on controlling the evolution of granite fractures in the future.