冲击载荷下叠合岩层巷道围岩的应力演化数值模拟研究——基于岩层运动并行计算系统StrataKing∗

煤系地层属于典型的层状沉积岩层，这在传统连续介质模型中不能被较好反映。为了探究冲击载荷下叠合岩层巷道围岩的应力演化规律，采用以拉格朗日元与离散元耦合连续?非连续方法为基础发展的岩层运动并行计算系统 StrataKing，基于理想化模型分析了巷道上表面附近应力波的叠加。阐明了应力波叠加导致顶板开裂机理，并且探讨了冲击载荷幅值的影响规律。研究发现：在原始压应力波传至巷道上表面附近测点后，该测点的最大主应力刚开始呈下降?上升?下降的变化趋势，这是由原始压、拉应力波不同时刻的叠加不同导致的；由于次级应力波的波长较原始应力波的小，次级压、拉应力波的单独作用更明显，它们的叠加使巷道上表面附近测点能产生更低和更高的最大主应力，甚至导致顶板开裂；冲击载荷幅值越大，近似阶梯增长阶段中拉裂纹平均发展速度越快，巷道围岩最终开裂范围越大，巷道围岩平衡越困难。

Numerical Simulation on Stress Evolution of Surrounding Rock around A Roadway in Composite Strata under Impact Load Based on Parallel Computing System for Strata Motion

Coal measure strata belong to typical layered sedimentary strata， which cannot be well simulated by use of the continuous model. In order to study the stress evolution of the surrounding rock around a roadway in composite strata under the impact load， the deformation-cracking processes of the surrounding rock were obtained through the parallel computing system for strata motion （based on the combined Lagrangian-discrete element method）. The superposition of stress waves near the upper surface of the roadway was analyzed based on an idealized model. The mechanism of roof cracking caused by the superposition of stress waves was expounded， and influences of impact load amplitudes were explored. The following results were found. When the initial compressive stress wave reaches the monitored node near the upper surface of the roadway， the maximum principal stress of the monitored node shows a down-up-down trend at the beginning， which is caused by the superposition of the initial compressive and tensile stress waves at different points in time. Owing to the wavelengths of secondary stress waves being shorter than those of initial stress waves， the independent effects of the secondary compressive and tensile stress waves are more obvious than those of initial stress waves. The superposition of secondary stress waves will generate much lower or higher maximum principal stresses at the monitored node near the upper surface of the roadway， even leading to roof cracking. With increasing impact load amplitudes， the tensile cracks propagate more rapidly at the stepped growth stage， the final cracking range in the surrounding rock of the roadway increases， and the equilibrium of the surrounding rock becomes difficult.