注水煤样力学及渗透特性试验研究

Experimental Study on Mechanical and Permeability Characteristics of Water Injection Coal Sample

为研究注水煤样吸水率与时间的关系,以及煤样的力学性能、渗透特性,首先对高家堡煤样进行了自然吸水率测定试验,然后在MTS815.03电液伺服试验机上进行了自然煤样与饱和水煤样单轴压缩试验,最后进行了水渗透试验。试验结果表明:在煤样吸水饱和前,煤样试件吸水率是浸泡时间的二次函数,浸水3.5 d后自然吸水率为3.37%,达到饱和水状态;与自然状态煤样相比,饱和水状态煤样出现轴向应力峰值时的轴向应变增大,出现"滞后"现象,泊松比和普氏系数分别降低了3.36%和9.07%,单轴抗压强度和弹性模量分别降低了20.97%和17.05%;渗透率曲线表明,应力应变过程中煤样渗透率变化可分为压实降低、缓慢增加、峰值出现和残余降低4个阶段,应力峰值超前于渗透率峰值。

In order to study the relationship between water absorption and time,mechanical properties and infiltration characteristics of coal sample,the natural water absorption test of Gaojiapu coal was carried out,and then single-axis compression test was carried out on MTS815.03 electro-hydraulic servo testing machine with natural and saturated water coal,and finally a water penetration test was conducted.The results showed that the water absorption is the secondary function of the immersion time before the coal sample is saturated,and the natural water absorption rate is 3.37% after 3.5 days of immersion to reach the saturated water state.Compared with natural coal sample,the axial strain increases with the axial stress peak in the saturated water state,and the "hysteresis"phenomenon occurs,and the Poisson's ratio and the Platts coefficient decrease by3.36% and 9.07% respectively,compressive strength and elastic modulus decreased by 20.97% and 17.05% respectively.According to the trend of permeability curve,the change of permeability during stress and strain can be divided into compaction reduction,slowly increasing,peak appearing and residual reduction in four stages.The peak of stress is ahead of the peak of permeability.