采动覆岩结构演化特征及对地表沉陷的影响分析

Influence analysis of between subsidence and structure evolution in overburden rock under mining

  • 摘要: 为掌握地下煤矿采空区覆岩层破坏特征及其对地表沉陷影响,准确预计地表移动变形值,针对不同的开采进度,从土力学与材料力学角度出发,分析了煤层上覆岩层结构变化特征,将其概化为3种形态梁模型:简支梁、悬臂梁、砌体梁,并考虑采空区是否充满与多层梁共存状态的情况,分别建立了相应的力学模型进行相关力学分析,依据公式推演分析了各阶段覆岩层的破断演化形态; 基于不同阶段的覆岩层结构破坏状态,详细揭示了各阶段之间演化规律,并依据梁变形理论推算出各阶段覆岩结构的变形公式; 结合离层在采空区净空间的传递衰减作用与其自身的动态发展过程,建立了充分采动离层从产生到发展为超充分采动离层的数学模型,推导出覆岩层的离层横向宽度; 根据离层最后阶段的动态变化与发展的横向宽度,通过将离层的横向宽度作为下一上覆岩层梁模型的跨空距离,设计出充满离层与未充满离层状态下地表变形下沉的理论预计模型; 为突出推导理论预计模型的相符性,通过实测数据与数值模拟相结合的方法对理论预计模型进行了验证,结合三道沟煤矿实测数据建立数值模拟模型,与实测数据进行比较得出最大相对误差为5.8%,在允许误差之内,将理论预计模型结果与数值模拟结果进行验证,验证了理论预计模型的合理性。

     

    Abstract: In order to understand the failure characteristics of overburden strata in underground coal mine goaf and its influence on surface subsidence, and accurately predict surface movement deformation, according to different mining progress, the structural change characteristics of overburden strata were analyzed from the perspective of soil mechanics and material mechanics, which were generalized into three types of shape beam models:simply supported beam, cantilever beam and masonry beam.Based on the failure state of overburden structure in different stages, the evolution law between stages was analyzed in detail, and the deformation formula of overburden structure in each stage was deduced according to the beam deformation theory.Combining the net space transmission attenuation effect of abscission layer in mined-out area with its own dynamic development process, a fully mining from production to the development of the gateway as the super full mathematical model of the mining gateway was established, and the abscission layer of overburden stratum at the lateral width was deduced.According to the dynamic change in the final phase of the gateway and the development of the lateral width, through the horizontal width of abscission layer as the next across the empty distance of overburden beam model, the theoretical model of surface deformation and subsidence with delamination and under-fill delamination was designed.In order to highlight the consistency of deriving the theoretical prediction model, the theoretical prediction model was verified by combining the measured data with the numerical simulation method.The numerical simulation model was established by combining the measured data of Sandaogou coal mine, and the maximum relative error was 5.8% compared with the measured data, which was within the allowable error.After that, the theoretical prediction model result and the numerical simulation result were verified to prove the rationality of the theoretical prediction model.

     

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