采动围岩边界时变过程特征分析

煤矿采动围岩的破坏、断裂和垮落是具有代表性的时变边界过程．本文针对俄霍布拉克煤矿实际情况，介绍了RFPA软件模拟采动围岩破坏、断裂和垮落过程的思路．分析了煤矿采动围岩时变边界问题的基本特征，对时变边界系统的力学行为进行了数学描述，研究表明：1）采动围岩的边界变化不单是开挖造成的，岩层的弯曲、断裂和垮落是造成边界时变的主要原因；2）巷道的掘进和煤层的开采打破了围岩原有的平衡状态，引起自由边界的局部破坏，并使靠近自由边界的裂纹急剧扩展，造成围岩承载力连续下降．承载能力的连续下降反过来造成自由边界的不断变化；3）采动围岩边界的不光滑性、内部的原生缺陷和因采动引起的断裂面分布的复杂性，数值方法是研究采动围岩破坏、断裂和垮落过程的首选方法；4）RFPA软件虽然不是基于时变边界动力学的概念开发的，但是可以定性地反映围岩由于破坏、垮落形成的时变边界以及边界变化对后继位移、应力场的影响．

Analysis of Time Change Process of the Mining Induced Surrounding Rock Boundaries

The failure,rupture and collapse of mining induced surrounding strata are a representative process in which the boundaries of dynamic system are variable.Basic conceptions about dynamics of systems with variable boundaries(DSVB) are introduced.Analysis of the characteristics of the variable boundaries of surrounding strata affected by mining(SSAM) is carried out,and the system of variable boundaries(SVB) is mathematically described.An opinion concerning the simulation of failure,rupture and collapse of SSAM by RFPA is put forward based on the case study of Ehuobulake Coal Mine.The result shows that 1) the variable boundaries of SSAM is caused not only by digging,but also by failure,rupture and collapse,2) the digging of channel or the mining of coal seam breaks the initial balance of surrounding strata,leading to a local destruction of free boundaries And an obvious decrease in carrying capacity of surrounding strata because of the new free boundaries,and vice versa,3) because of the unsmoothed boundaries of SSAM,numeric simulation is the preferred method of working over the process of failure,rupture and collapse of SSAM,4) although the RFPA is not developed on the basis of DSVB,it can qualitatively describe the variable boundary of SSAM and its influence upon the subsequent fields of displacement and stress.