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西部矿区弱胶结地层工程围岩稳定性控制研究进展

Research progress on stability control of surrounding rock in weakly cemented strata engineering in western China mining area

  • 摘要: 我国西部矿区开采地层主要由侏罗系、白垩系地层构成,该地层岩石总体表现为强度低、胶结性差、易崩解等特性,属于弱胶结岩石。弱胶结地层工程围岩与中东部矿区地层岩石差异性较大,工作面顶板控制、巷道围岩控制等采用传统的控制技术很难有效保障工程的安全性,常出现巷道大变形失稳、工作面压架、突水、溃沙、冲击地压等灾害。通过大量的调研和室内试验,获得弱胶结岩石抗拉、抗压等力学指标远小于中东部矿区同类岩石力学指标,建立了多因素耦合作用下的弱胶结岩石的变异程度评估指标体系,初步获得了典型矿区弱胶结岩石的变异性程度。以红庆河煤矿弱胶结岩石为例,发现了弱胶结岩石在力、水等载荷作用下,具有“类相变”现象,分析了胶结度对类相变现象的影响,给出了弱胶结粗粒砂岩的“类相变”状态特征及其敏感性参数。分析了导致工作面支架压架、突水溃沙灾害发生的覆岩垮落带、断裂带动态发育规律以及巷道围岩大变形规律,推演了弱胶结地层大采高工作面不同开采阶段垮落带动态变化表达式,建立了支架−围岩相互作用模型,给出了工作面来压和非来压期间支架工作阻力;针对弱胶结地层的松散弱特性,提出了巷道围岩双壳加固技术,可为工作面安全开采和巷道围岩控制提供保障。

     

    Abstract: The mining strata in the western mining area of China are mainly composed of Jurassic and Cretaceous strata. The strata are characterized by low strength, poor cementation and easy disintegration, which belong to weakly cemented rocks. The surrounding rock of the weakly cemented stratum project is quite different from the stratum rock of the central and eastern mining areas. It is difficult to effectively guarantee the safety of the project by using traditional control technologies such as roof control of the working face and surrounding rock control of the roadway. Disasters such as large deformation and instability of the roadway, crushing of the working face, water inrush, sand inrush, rock burst and so on. Through a large number of investigations and laboratory experiments, the mechanical indexes such as tensile and compressive strength of weakly cemented rocks are much smaller than those of similar rocks in the central and eastern mining areas. The evaluation index system of the variation degree of weakly cemented rocks under the coupling of multiple factors is established, and the variation degree of weakly cemented rocks in typical mining areas is preliminarily obtained. Taking the weakly cemented rock in Hongqinghe Coal Mine as an example, it is found that the weakly cemented rock has the phenomenon of ‘phase transition’ under the action of force, water and other loads. The influence of cementation degree on the phase transition phenomenon is analyzed, and the ‘phase transition’ state characteristics and sensitivity parameters of weakly cemented coarse-grained sandstone are given. The dynamic development law of overburden caving zone and fracture zone and the large deformation law of roadway surrounding rock are studied and analyzed, which lead to the support crushing, water inrush and sand inrush disasters in the working face. The dynamic change expression of caving zone in different mining stages of large mining height working face in weakly cemented strata is deduced, and the support-surrounding rock interaction model is established. The working resistance of support during weighting and non-weighting of working face is given. Aiming at the loose and weak characteristics of weakly cemented strata, the double shell reinforcement technology of roadway surrounding rock is proposed, which can provide guarantee for safe mining of working face and control of roadway surrounding rock.

     

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