流变扰动条件下岩石微观损伤试验研究

Experimental study on micro-damage of rock under rheological disturbance

  • 摘要: 高地应力与开采扰动2个因素会导致深部岩体的变形失稳破坏,在高地应力作用下深部岩体进入强度极限邻域,进入强度极限邻域的岩体对开采扰动非常敏感,开展岩石流变扰动效应微观损伤试验相关研究是解决问题的关键。为满足研究过程中的试验需求,研发了岩石流变扰动效应微观损伤试验系统,该试验系统通过对扰动加载装置的升级改造完成了试验仪主机的优化,拓展了岩石流变扰动效应微观损伤试验功能,采用该试验系统进行了相应的试验研究。试验结果表明:① 岩石流变扰动效应微观损伤试验系统性能可靠,适用于岩石流变扰动效应微观损伤试验的相关研究;② 当岩石进入强度极限邻域时,试件孔径大于1 μm的大尺寸孔隙增长幅度远大于孔径小于1 μm的小尺寸孔隙的增长幅度和孔隙压密幅度,造成岩石内部不可逆损伤;③ 不同围压流变扰动条件下,当试件处于强度极限邻域外时,围压对试件孔隙的扩张发育有一定的抑制作用,试件内部孔隙的压密幅度要大于其扩张幅度,而随着围压增大,进入强度极限邻域时,围压的存在一定程度上加快了孔隙的扩张发育,试件内部孔隙以扩张发育为主导;④ 确定了岩石进入强度极限邻域的微观判别标准,即当流变扰动条件下孔径大于1 μm的大尺寸孔隙占比量增长幅度升高显著时,表明岩石已进入强度极限邻域。

     

    Abstract: High in-situ stress and mining disturbance will lead to the deformation and instability of deep rock mass. Under the action of high in-situ stress, deep rock mass enters the strength limit neighborhood, and the rock mass entering the strength limit neighborhood is very sensitive to mining disturbance. Research on micro-damage test of rock rheological disturbance effect is the key to solve the problem. In order to meet the test requirements in the research process, a micro-damage test system for rock rheological disturbance effect was developed. The test system optimized the host of the tester by upgrading the disturbance loading device, and expanded the micro-damage test function of rock rheological disturbance effect. The test results show that: ① The performance of rock rheological disturbance effect micro-damage test system is reliable, which is suitable for the related research of rock rheological disturbance effect micro-damage test; ② When the rock enters the strength limit neighborhood, the growth rate of large-sized pores with a pore size greater than 1 μm is much larger than the growth rate and pore compaction amplitude of small-sized pores with a pore size less than 1 μm, resulting in irreversible damage inside the rock; ③ Under different confining pressure rheological disturbance conditions, when the specimen is outside the strength limit neighborhood, the confining pressure has a certain inhibitory effect on the expansion and development of the pores of the specimen, and the compaction amplitude of the pores inside the specimen is greater than its expansion amplitude. With the increase of confining pressure, when entering the strength limit neighborhood, the existence of confining pressure accelerates the expansion and development of pores to a certain extent, and the internal pores of the specimen are dominated by expansion and development; ④ The microscopic criterion for the rock to enter the strength limit neighborhood is determined, that is, when the proportion of large-sized pores with pore size greater than 1μm increases significantly under the condition of rheological disturbance, it indicates that the rock has entered the strength limit neighborhood.

     

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