松基比对巨厚松散层下开采地表移动影响研究——以菏泽矿区为例

Research on the Impact of Loose-to-Base Ratio on Surface Movement of Mining Under the Thick Loose Layer: Taking Heze Mining Area as an Example

摘要

为深入研究巨厚松散层下开采的地表移动规律,以山东菏泽矿区为例,基于地表变形现场实测数据,采用 FLAC^3D 软件建立了 12 种不同松基比(0.25 ~ 5.00)下的数值计算模型。获取了地表变形参数,分析了覆岩应力与地表变形特征,研究了地表变形参数的变化规律。结果表明:(1)受巨厚松散层和含水层失水沉降的耦合影响,地表下沉系数偏大,地表沉陷响应较迅速,起动距为 0.2H(H 为平均深度)。下沉盆地边界区域的衰退特征明显,下沉盆地范围先急剧扩张随后减缓直至最终收敛。(2)在采深不变的情况下,当松基比不断增大时,地表下沉系数先增大后减小,水平移动系数先增大后减小最终趋于稳定,主要影响角正切先增大后减小。松基比为 1.50~2.00 时,地表变形达最大值。(3)采空区中心上方覆岩破坏以拉破坏为主,随松基比增大拉应力先增大后减小。采空区边界上方由拉应力和压应力共同作用,采空区两侧压应力随松基比增大而减小。

Abstract

In order to deeply study the surface movement law during mining under a thick loose layer, taking the Heze mining area in Shandong Province as an example and based on the field measurements of surface deformation, 12 numerical models were established using FLAC ^3D at different thickness ratios of the loose layer to the bedrock (hereinafter referred to as the loose-to-base ratios) ranging from 0.25 to 5.00. The surface deformation parameters were obtained, analyses were carried out on the stress of the overlying rock and the characteristics of surface deformation, and studies were conducted on the variation law of the surface deformation parameters. The results are as follows: (1) The surface subsidence coefficient is relatively large and the surface subsidence response is rapid because of the combined influence of the thick loose layer and the aquifer subsidence caused by water loss. The starting distance is 0.2H (H represents the average depth). The recession characteristics of the boundary area of the subsidence basin are obvious, and expand rapidly first and then slow down until finally converging. (2) When the mining depth remains constant, as the loose-to-base ratio keeps rising, the subsidence coefficient initially goes up and then declines. The horizontal movement coefficient first increases, subsequently decreases, and ultimately becomes stable. The tangent of the main influence angle also shows an upward-then-downward trend. It is found that when the loose-to-base ratio ranges from 1.50 to 2.00, the surface deformation attains its peak value. (3) Above the center of the goaf, the failure of the overlying rock is mainly tensile failure. As the loose-to-base ratio increases, the tensile stress first increases and then decreases. Above the boundary of the goaf, it is affected by both tensile and compressive stresses. The compressive stresses on both sides of the goaf decrease as the loose-to-base ratio increases.

关键词

巨厚松散层 / 开采沉陷 / 数值模拟 / 地表变形参数 / 松基比

Key words

thick loose layer / mining subsidence / numerical simulation / surface deformation parameters / loose-to-base ratio

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基金资助

国家自然科学基金资助项目(52174156)

安徽省高校协同创新项目(GXXT-2020-055)