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煤矿开采覆岩拱壳结构演化及其控制研究进展

Research progress on the evolution and control of overlying rock arch structure in coal mining

  • 摘要: 煤层开采引起覆岩的移动、变形、破断及应力变化是造成工作面来压及地表生态损伤的主要原因。研究采动覆岩运动规律与损伤机理是解决井下安全生产、含水层保护、地表建(构)筑设施与生态保护的核心问题,是实现煤矿绿色安全开采的理论基础。为充分认识开采损伤的传导机制,以覆岩承载“拱壳”结构为核心,系统梳理了当前覆岩运动研究成果,针对覆岩组合与岩土体介质特性差异,将研究成果分为松散层拱和基岩拱。基岩拱又可以进一步分为断裂拱和应力拱。在此基础上,依据拱壳演化机制和研究手段论述了基岩拱壳研究进展与不足:理论模型能够给出拱迹线方程进而判断拱的承载特征;但存在边界应力条件简化、岩层均质性假设、拱迹线的假设和拱厚度的计算等问题;数值模拟可以很好的给出拱壳的位置、拱厚及其演化特征,但以有限元模拟的应力拱壳忽略了岩层破断的影响,而以离散元模拟的应力或者裂断拱壳则依赖于块体的划分;相似模拟目前只能定性观测裂断拱的发育特征,难以确定应力拱范围。现有基于覆岩拱壳的应用聚焦于通过拱壳演化模型进行矿压和地表沉陷的预测与防治,对主动调控覆岩拱壳的手段相对较少的问题,基于此,归纳了3种覆岩拱壳调控手段:源头预设拱壳手段、过程调控拱壳手段、末端稳控拱壳手段。最后综合现有成果,进一步提出了基于能量守恒定律的采动损伤拱壳理论计算模型及其模拟方法,为采场覆岩空间结构稳定性演化特征及地表沉陷治理提供了理论支撑与研究手段。

     

    Abstract: The movement, deformation, fracture, and stress changes of overlying strata caused by coal mining are the main reasons for the weighting on the longwall face and surface ecological damage. Studying the movement laws and damage mechanisms of overlying strata during mining is the core issue in solving underground safety production, aquifer protection, surface construction facilities, and ecological protection. It is the theoretical basis for achieving green and safe mining in coal mines. To fully understand the conduction mechanism of mining damage, taking the overburden "arch shell" structure as the core, the current research results of overburden movement are systematically reviewed. According to the difference of overburden combination and medium characteristics, the arch in mining field are divided into loose layer arch and bedrock arch. Bedrock arches can be further divided into fracture arches and stress arches. On this basis, the research progress and existing problems of bedrock arch are discussed according to the arch shell evolution mechanism and research methods: The theoretical model can give the arch trace equation and judge the bearing characteristics of the arch. However, there are some problems, such as simplification of boundary stress conditions, assumption of rock stratum homogeneity, assumption of arch trace and calculation of arch thickness. Numerical simulation can well give the location, thickness and evolution characteristics of arch shell. However, the stress arch shell simulated by finite element ignores the influence of rock fracture, while the stress or fracture arch shell simulated by discrete element depends on the division of blocks. Similar simulation can only qualitatively observe the development characteristics of fracture arch, and it is difficult to determine the range of stress arch. The existing applications based on overlying rock arch shells focus on predicting and preventing longwall face weighting and surface subsidence through arch shell evolution models. However, there are relatively few methods for actively regulating overlying rock arch shells. Based on this, this paper summarizes three methods for regulating overlying rock arch shells: source preset arch shell method, process control arch shell method, final stability control arch shell method. Finally, based on the existing achievements, a theoretical calculation model and simulation method for mining damage arch shell theory based on the law of energy conservation were further proposed. It provided the theoretical support and research methods for the evolution characteristics of the overlying rock fracture structure stability in the longwall face and the treatment of surface subsidence.

     

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