Li Meng, Zhang Jixiong, Meng Guohao, Zhang Qiang, Sun Kai
State Key Laboratory of Coal Resources and Safe Mining, China University of Mining and Technology, Xuzhou, 221116, China.
School of Mines, China University of Mining and Technology, Xuzhou, 221116, China.
Environ Sci Pollut Res Int. 2023 Jan;30(5):13393-13406. doi: 10.1007/s11356-022-23041-5. Epub 2022 Sep 21.
Granular waste rocks filled in goaf can replace coal seams to support roofs, thus reducing the extent of overlying strata movement, and thus reducing the environment damage caused by coal mining. To better to control the compression-induced deformation (CID) of waste rocks for backfill (WRBs), a loose material, it is feasible to apply lateral cyclic loads on granular waste rocks in advance. In order to study the effect of lateral cyclic loading on granular waste rocks, by utilising pre-lateral cyclic loading and axial loading, the deformation of granular waste rocks under load was tested on a compression simulation experimental platform for solid backfill materials. Furthermore, the changes in displacement, stress and mass of granular waste rocks during lateral cyclic loading were attained. The test results showed that (1) the loading stress progressively increased with the growth of the loading displacement, in which the rising process was divided into three stages according to the rate of loading. (2) With the increase in number of loading cycles, the rate of increase of stress in stage I increased and the stress reached increasingly higher levels; at the same time, stage II was gradually shortened. Eventually, only a single stage prevailed as the stress rapidly reached its preset maximum value, and the final displacement of the samples gradually declined. (3) The axial stress-strain curves of the samples exhibited a quasi-exponential relationship. Through lateral cyclic loading, the relative density of WRBs was significantly improved, and their deformation resistance was strengthened. (4) During backfill mining, lateral cyclic loads were applied to granular waste rocks, which improved the bearing capacity thereof and reduced strata movement and surface subsidence. This is beneficial to the protection of the surface environment and surrounding buildings.
采空区内充填的粒状矸石可替代煤层支撑顶板，从而减小上覆岩层的移动范围，进而减少煤炭开采对环境的破坏。为了更好地控制用于充填的松散材料——矸石的压缩变形，预先对粒状矸石施加侧向循环荷载是可行的。为了研究侧向循环荷载对粒状矸石的影响，利用预先的侧向循环荷载和轴向荷载，在固体充填材料压缩模拟试验平台上对粒状矸石在荷载作用下的变形进行了测试。此外，还获得了粒状矸石在侧向循环荷载作用下位移、应力和质量的变化情况。试验结果表明：（1）荷载应力随荷载位移的增加而逐渐增大，根据加载速率，其上升过程分为三个阶段。（2）随着加载循环次数的增加，第一阶段应力的增加速率增大，应力达到的水平越来越高；同时，第二阶段逐渐缩短。最终，只有一个阶段占主导，应力迅速达到其预设最大值，试样的最终位移逐渐减小。（3）试样的轴向应力-应变曲线呈现准指数关系。通过侧向循环加载，矸石的相对密度显著提高，其抗变形能力增强。（4）在充填开采过程中，对粒状矸石施加侧向循环荷载，提高了其承载能力，减少了岩层移动和地表下沉。这有利于保护地表环境和周边建筑物。
