深部近距离煤层群卸压开采应力场演化效应与致灾机理研究

The evolving patterns of mining-induced macro-stress and energy field has been investigated in multi-seams mining that it is the key factor to result into dynamic rock or coal disaster. To study the superposition effect and its disaster-causing mechanism of stress and energy field development is an important and imperative for how to take coal mine ground control and integrated coal exploitation and gas extraction as a combined cross subject. Theory analysis， material simulation experiment， numerical simulation， and observation will been adopted to investigate into some innovation research. Firstly， based on analyzing mining-induced stress development， strata movement， geological conditions and strata structure in multi-seams mining， relationship among mining geology characteristics will be open up. Secondly， to design experimental scheme of numerical and material simulation with distress mining the lower seam， the upper seam and the middle seam primarily， development characteristics of stress field， fissure field， and displacement field will be obtained by simulating based on deep initial stress patterns. Thirdly， the mathematic and mechanic development model will be built to appropriately describe evolving patterns of mining-induce high stress and energy field based on analyzing simulated data. And rock or coal dynamic instability criterion will be deduced by applying energy mutation theory. Fourthly， the calculation soft of stress and energy development will be designed and programmed and will be a new compressive method to study concentration and release of energy in fissure rock-coal during mining deep closed multi-seams. Research will supply theory bases and engineering in coal mining and gas extraction， preparing and rock-coal control of dynamical disaster.

多煤层开采导致的宏观应力场与能量场的动态演化是引起煤岩动力灾害的关键因素之一，应力场和能量场的叠加效应及其致灾机理研究是矿山压力与煤与瓦斯共采交叉领域的前沿性课题。本项目采用理论分析、实验研究、数值模拟与现场监测相结合的方法，拟开展如下创新性工作：（1）分析多煤层开采采动应力演化、岩层运移与煤系地层赋存应力环境和岩层结构的关系；（2）设计并开展考虑深部原岩应力场分布的近距离煤层群上向、下向、双向卸压开采的数值和相似模拟试验，获得不同卸压开采应力场、裂隙场和位移场演化特征；（3）构建能够描述深部近距离煤层群卸压开采采动高应力和能量场动态演化的数学力学模型，提出基于能量突变的深部煤岩体动力失稳判别准则；（4）编制应力场和能量场时空演化的计算软件，为有效研究近距离煤层群开采过程中裂隙煤岩体的能量积聚与释放及致灾机理探索新途径。本项目对煤与瓦斯共采和煤岩动力灾害防治具有重要的理论意义和实用价值。

深部煤炭资源开采表明，高地应力影响下多煤层开采的应力演化叠加是导致剧烈矿压、冲击地压、煤与瓦斯突出等煤岩动力灾害易发的关键因素，弄清其演化机制是煤与瓦斯共采参数设计与煤炭安全高效开发的基础。根据两淮矿区朱仙庄矿和潘二煤矿煤层群开采为工程背景，采用现场实测、实验室实验、数值模拟、相似模拟试验以及理论计算相结合的方法，对影响深部多煤组煤层群卸压开采应力场演化与致灾机理的关键因素进行了深入研究。主要研究结果如下：（1）基于煤岩层结构特征和煤岩体物理力学测试数据分析，构建了多煤组煤层群卸压开采分析模型；（2）基于Monte Carlo方法，提出了地应力测量可靠性分析及其误差估算方法；（3）构建了考虑地应力+采动应力数值模拟模型，获得了基于实测地应力的工作面采动应力分布及其演化特征；（4）获得了近距离煤层群下行卸压开采过程中采场围岩应力、位移、变形、破坏特征，揭示了多次采动高应力演机制及其对采动裂隙的动态效应;（5）构建了深部近距离煤层群下行卸压开采采动高应力演化模型，推导了多次采动高应力、裂隙演化形态计算公式及卸压范围的计算方法，完善了多煤层卸压开采理论计算体系;（6）揭示了煤层群多煤层开采采动高应力演化对煤岩体能量积聚、释放机制的作用机理;（7）揭示了深部多煤组煤层群卸压开采多关键层运移－应力裂隙演化机制及其对瓦斯抽采效果的影响规律。研究成果的应用不仅为卸压瓦斯抽采钻孔的布置和以采动高应力演化为主导作用的煤岩动力灾害防治提供了理论基础，也为卸压开采采场参数设计与优化、采场和巷道围岩稳定性控制等提供了技术支持。