煤柱体应力松弛特性的试验研究

Experimental Study on Stress Relaxation Characteristics of Coal Pillar

为了研究高宽比对煤柱应力松弛现象随时间变化规律的影响,制作了高宽比不同的煤柱体试件,通过分级应变加载的单轴压力试验,对高宽比不同的煤柱进行了应力松弛试验研究。结果表明:应力松弛过程分为3个阶段:骤降阶段、缓慢下降阶段、稳定阶段。应变级别一定时,随着高宽比的增大,应力松弛现象持续的时间增长,初始应力和残余应力均变小,而应力松弛量和松弛比均变大;高宽比一定时,增大应变级别,应力松弛量随之增加,而应力松弛比却减小。此研究可为煤柱的安全性和延长使用寿命提供一定的试验依据。

In order to study the influence of the high aspect ratio on the stress relaxation phenomenon of coal pillar with time, we have made coal pillar specimen with different high aspect ratio, and carried out the stress relaxation test under graded loading and strain control. The results show that, the stress relaxation process is divided into three stages： the sudden drop stage, the slow decline stage and the stable stage. When the strain level is constant, with the increase of high aspect ratio, stress relaxation phenomenon of coal pillar increases constantly with time, the initial stress and the residual stress decreases, while the stress relaxation amount and relaxation ratio are increased. When the high aspect ratio is constant, the stress relaxation amount is increased with the increase of strain level, while the stress relaxation ratio decreased. This study can provide a certain test basis for the safety and extend service life of the coal pillar.