构造应力作用下覆岩卸压演化规律试验研究

Experiment study of relief evolution of the overlying strata under the effect of the tectonic stress

覆岩运移是一个伴随煤层开采的时空变化而不断演化的动态过程。通过对煤层开采与岩层卸压的动态演化进行关联分析发现，伴随着煤层的开采，上覆岩层的卸压范围处于不断变化中。为了掌握卸压范围变化的规律，采用相似材料模拟试验的方法，将覆岩按层位进行划分，在各层位布设应力监测点。通过对各应力监测点采集的数据进行分析发现，在开采过程中，其上位岩层卸压范围在宏观上呈现先增加后减小并最终恒定的过程，进而得出随开采其卸压范围变化的规律，以及最大卸压区间出现的位置。并且通过加载水平应力场发现，水平应力的作用加强了岩层自承能力，削弱了岩层自重引起的卸压，岩层初始卸压层位发生了变化，卸压呈现跳跃发展。关键层结构对于岩层卸压起到了一定的控制作用。对比支承压力峰值发现，支承压力在纵向分布以35～41m为分界，分界线上受支承压力影响较小，无明显变化规律。

This paper is to report the results of our similar material simulation experimental study on the relationship between the mining process and the rock seam pressure relief. As is known, the strata migration is by nature a constantly evolving dynamic process, which has been changing with the time and space in the mining process. In accordance with the said features, through the analysis of the evolu- tionary dynamics relationship between the mining process and the rock seam pressure relief, it can be concluded that, at different mining stages, the mining pressure relief range keeps in constant variation. In order to clarify the regularity of the associated changes, it is ad- vised to apply a similar material simulation method that at the begin- ning of the experiment, the overlying strata of the model can be di- vided into different strata, with the stress monitoring points lying in each layer. When analyzing the data extracted from the stress moni- toring points, we can find that, in the macroscopic sphere, the pres- sure relief range of the upper strata tends to increase first and de- crease later, and eventually reaches a constant equilibrium in the mining process. And, in such a case, it is necessary to make clear that the results of the changing regularity of the pressure relief range is likely to accompany the mining process and we should be able to look for the location of the maximum pressure relief range. And, now it is possible for us to find by putting the horizontal stress on the mod- el that the rock itself has its own weight and promotes the pressure re- lief, thus leading to its own pressure relief. However, change has taken place when the rock strengthened its self-weight, but slackened the pressure relief under the effect of the stress. In such a situation, changes would take place with the position of the initial pressure relief layer and the pressure relief tends to leap-forward abruptly. Howev- er, the key layer structure is likely to give a certain stimulating push for the rock unloading. All in all, a careful comparative and contrast analysis of the peak value of the bearing pressure helps to disclose the boundaries of the bearing pressure distribution in the longitudinal way from 35 m to 41 m, whereas the bearing pressure of the rocks may have little effect on the dividing line, and in turn no significant varia- tion they may lead to.