高温后岩石三轴变形及渗透率演化规律

Regularity of Permeability Evolution of Rock after High Temperature

对于深部采矿工程、核废料贮存、地热资源开发及利用等工程领域来说,岩石的热-力-液耦合研究是极为重要的。为研究高温后岩石变形及渗透率演化规律,对某塔里木地区矿井岩石进行不同温度下的热破裂处理后,进行了三轴应力下的加载试验,从强度、渗透率等方面对岩石力学特性进行了分析。结果表明:(1)加载初期,围压增大使渗透率降低,加载中期渗透率缓慢增大,加载后期渗透率急剧增大;(2)岩石渗透率随温度升高增大,且呈正指数增长;(3)温度低于一定值下岩石的热膨胀性不明显,而较高温度引起的热膨胀会明显破坏岩石结构,使其弹性模量和强度随温度的升高降低,渗透率随着温度的升高增大;(4)利用热力学理论,推导出温度变化时热应力所引起的岩石裂隙的变化,从而得到了渗透率随温度变化的模型。研究结果对于高温下多场耦合问题的研究有参考价值。

Research on the heat-force-liquid coupling of rock is extremely important for deep mining engineering,nuclear waste storage,geothermal resources exploitation and utilization and other engineering fields.In an attempt to study the permeability evolution regularity of rock after high temperature,the mechanical properties of rock mass undergone thermal fracture treatment at different temperatures were analyzed in terms of strength and permeability through triaxial loading test.Rock samples collected from a mining well in Tarim were taken as research objects.Results manifested that:(1)In the initial stage of loading,the climbing of confining pressure led to lower permeability;in the mid-stage,permeability increased slowly;in the later stage of loading,permeability increased dramatically.(2)The permeability of rock increased in positive exponential relation with the rising of temperature.(3)The thermal expansion of rock was unapparent below a certain temperature,while thermal expansion induced by higher temperature would significantly damage rock structure,mitigating the increasing of elastic modulus and strength with the rise of temperature.(4)In line with the theory of thermodynamics,the rock fracture caused by thermal stress under varying temperature was deduced,and the model of permeability varying with temperature was obtained.The results offer reference for the study of multi-field coupling under high temperature.