断层邻近倾斜煤层开挖回填与不回填围岩响应对比研究

Comparative Study on Surrounding Rock Response of Inclined Coal Seam Excavation with and without Backfilling near a Fault

摘要: 为比较断层邻近倾斜煤层开采中采空区回填对围岩响应的影响，建立含上盘、断层弱化带和下盘的三维数值模型，设置仅开挖不回填和边开挖边回填两种工况，模拟工作面沿x方向分步推进过程中垂向应力、垂向位移和塑性区的演化。工作面布置于上盘煤层内，由x = 190 m推进至x = 310 m，步距10 m，共推进12步；在第12步回填工况基础上，对围岩弹性模量、围岩黏聚力及抗拉强度、断层带强度参数和等效上覆荷载进行±20%单因素扰动。计算结果显示，在既定参数和及时回填假定下，回填体承担部分上覆荷载，采空区支承状态得到改善。第12步时，仅开挖工况最大下沉量为2936.85 mm，回填工况为64.16 mm，降低97.82%；塑性单元数由870个降至95个，降低89.08%；峰值垂向压应力由19.03 MPa增至25.65 MPa，反映回填体参与了荷载传递。三项响应指标对等效上覆荷载的敏感性均最高。模型参数取自现有FLAC3D建模文件，尚未通过现场岩样试验、RMR/Q分级和地应力实测进行独立反演；断层按弱化带处理，且未考虑断层面滑移、回填滞后、压实及渗流耦合作用。所得结果主要用于比较两种工况的相对差异和参数变化趋势，不宜直接作为具体矿井沉降量或破坏范围的定量预测。

Abstract: A three-dimensional numerical model containing the hanging wall, a weakened fault zone and the footwall was established to examine the influence of goaf backfilling on an inclined coal seam near a fault. Excavation without backfilling and excavation with immediate backfilling were simulated during a 12-step advance from x = 190 m to x = 310 m at a step length of 10 m. For the Step-12 backfill case, one-factor-at-a-time perturbations of ±20% were applied to the surrounding-rock elastic modulus, surrounding-rock cohesion and tensile strength, fault-zone strength parameters and equivalent overburden load. At Step 12, backfilling reduced the maximum subsidence from 2936.85 mm to 64.16 mm and the number of plastic elements from 870 to 95, while the peak vertical compressive stress increased from 19.03 MPa to 25.65 MPa as the backfill participated in load transfer. All three response indices were most sensitive to the equivalent overburden load. The mechanical parameters were adopted from the existing FLAC3D input files but were not independently calibrated using site-specific laboratory tests, RMR/Q classification or in-situ stress measurements. The results are therefore interpreted as relative responses and parameter trends rather than direct quantitative predictions for a specific mine.