沿空留巷巷旁充填体稳定机理研究

The backfilled body in gob-side entry retaining is generally subjected to several challenges including long-time roof cracking and dynamic loading, high stress concentration, and strong longwall abutment pressures, etc. However, the interaction between the backfilled body and the key structure in nearby roof has not been well understood. Hence, it is widely reported that uncontrollable deformation and even complete failure are encountered in gob-side entry retaining due to the failure of the key structure resulting from a poor understanding on the mechanical behavior of a desired backfilled body. To this point of view, this study is focused on the stability mechanism of backfilled body in gob-side entry retaining. The first issue needing to be addressed is to obtain the influence of main-roof cracking on the stability of the backfilled body. A three-dimension mechanical model involving the movement of key structure in roof will be developed to fix this concern. In addition, the necessary mechanical feature of the backfilled body needs to be studied. To achieve this goal, the supporting performance, deformation characteristics and yield-zone development of the backfilled body will be elaborated. Finally, a failure criterion for a post-peak backfilled body will be proposed. By analyzing the influence of confinement on the stability of the post-peak backfilled body, the stability mechanism and the supporting strategies of the post-peak backfilled body will be discussed and verified. Thus, the findings of this study would shed lights on the determination of the desired mechanical features of backfilled body, and on the improvement of the supporting strategies to ensure the stability of the post-peak backfilled body.

沿空留巷巷旁充填体经历顶板活动持续时间长、产生应力集中度高、动压影响强烈，充填体与顶板关键块结构相互作用关系研究不足，充填体力学性能设计不合理导致沿空留巷关键块结构失稳、围岩强烈变形甚至报废的现象时有发生。为此，开展沿空留巷巷旁充填体稳定机理研究，主要包括：1）分析基本顶破断与充填体相互作用关系，建立沿空留巷关键块结构三维力学模型，研究该结构的稳定状况与充填体力学性能的关系及影响规律；2）在保持关键块结构稳定的前提下，研究充填体应具备的力学性能，分析充填体变形特征、塑性区演化规律及承载变化规律，研究充填体变形与承载的主要影响因素及效应，确定充填体力学性能；3）研究塑性状态充填体的稳定性判别准则，分析侧向约束力与塑性状态充填体的相互作用关系，揭示充填体稳定机理，开发保持塑性状态充填体稳定的控制方法。研究成果可为沿空留巷巷旁充填体力学性能的确定与充填体稳定性控制提供依据。

长期以来，采区巷道普遍采用留煤柱的方式护巷，不仅煤炭采出率较低、巷道维护困难，而且较宽的煤柱在工作面后方形成应力集中，使布置在煤柱下方的岩巷或下层煤回采巷道维护困难，研究沿空留巷实现无煤柱开采具有重要意义。但由于沿空留巷巷旁充填体经历顶板活动持续时间长、产生应力集中度高、动压影响强烈，充填体与顶板关键块结构相互作用关系研究不足，充填体力学性能设计不合理导致沿空留巷关键块结构失稳、围岩强烈变形甚至报废的现象时有发生。因此，本课题以沿空留巷顶板应力对巷旁充填体作用为主线，综合运用多种方法研究分析，得到以下几点结论：1）分析了基本顶破断与充填体相互作用关系，建立了沿空留巷关键块结构三维力学模型，研究得到了该结构的稳定状况与充填体力学性能的关系及影响规律；2）研究了充填体应具备早凝、快速增阻、良好变形性能和后期强度高的力学性能，分析了充填体变形特征、塑性区演化规律及承载变化规律，得到了充填体变形与承载的主要影响因素及效应；3）分析了侧向约束力与塑性状态充填体的相互作用关系，揭示了充填体稳定机理，开发了保持塑性状态充填体稳定的预应力控制方法，同步实现充填和加固充填体，增加了充填体的承载能力和抗横向变形能力。通过开展本项目研究，对于揭示充填体的变形机理具有重要意义，研究成果可为沿空留巷巷旁充填体力学参数的确定与充填体稳定性控制提供基础依据。