为研究煤层开采过程中底板渗透性变化规律，利用Rock Top 多场耦合试验仪，采用稳态和瞬态2 种方法测得不同应力作用下红砂岩渗透率，对红砂岩加载过程中内部裂纹发展变化规律及渗流特性进行分析，结果表明：对岩样进行应力差20 MPa 等梯度加载，全应力-应变曲线呈台阶状，根据裂纹体积应变法确定应力-应变各阶段的应变阈值，可将其划分为5 个阶段：压密闭合阶段—线弹性阶段—裂纹稳定扩展阶段—裂纹非稳定扩展阶段—峰后应变与破坏阶段;利用渗流进、出水口双泵设计，在5 个渗透压差下利用稳态法测试不同应力作用下岩石渗透率，结果表明在不同渗透压差下岩石渗透率均经历缓慢下降—缓慢增加—快速增长3 个阶段，与全应力-应变-渗流曲线规律一致，并与试件内部裂纹发展规律相对应;采用瞬态法测试得不同应力差下渗透率变化规律，与稳态法-渗流规律相一致，由于测试方法不同，瞬态法比稳态法测得岩样渗透率高出1～2 个量级，均表明红砂岩属于低渗类岩石;通过对完整岩样施加不同应力差模拟底板岩体状态，发现煤层底板压缩区渗透性减小，膨胀区渗透性增大，随着工作面推进，底板渗透性呈现先减小后增大的趋势，试验结果进一步揭示了随工作面推进底板岩体的渗流特性，为底板突水防治提供了重要的理论依据。

In order to study the change rule of floor permeability in the process of coal seam mining,Rock Top multi-field coupling test instrument was used to measure the permeability of red sandstone under different stresses by steady-state and transient methods,and the development and change rule of internal cracks and seepage characteristics during the loading process of red sandstone were analyzed. The results show that the stress difference of the rock sample is equal to 20 MPa,and the stress-strain curve is step-like. According to the crack volume strain method,the strain threshold of each stage of stress-strain can be divided into five stages:compression and sealing stage-linear elastic stage-crack stable growth stage-crack unstable growth stage-post-peak strain and failure stage;using the seepage inlet and outlet of the double pump design,using the method of steady state under five osmotic pressure difference under different stress test of rock permeability and shows that rocks permeability under different osmotic pressure difference are experiencing rapid growth slow decline-slow increase-three stages,with the stress and strain-seepage curve law is consistent,and correspond to specimen internal crack law of development;the permeability variation law under different stress differences measured by the transient method is consistent with that of the steady-state method. Due to different testing methods,the permeability of rock samples measured by the transient method is 1～2 orders of magnitude higher than that measured by the steady-state method,indicating that the red sandstone belongs to the type of low-permeability rock;applying different differential stress simulation based on complete sample floor rock mass state,found that the compression zone coal floor permeability decreases,and expansion zone permeability increase,with the working face advancing,floor permeability shows the tendency of increase with the decrease of the first,the results further reveal the with the working face advancing floor seepage characteristics of rock mass,provide important theoretical basis for prevention and control of floor water inrush.

0 引言

1 工程概况

2 渗流试验原理及方法

   2.1 试样制备

   2.2 试验装置

   2.3 试验原理

   2.4 试验方案及步骤

3 试验结果与分析

   3.1 加载过程中裂纹扩展分析

   3.2 红砂岩稳态法渗流规律

   3.3 红砂岩瞬态法渗流影响规律

4 结论