乌海矿区多煤层开采地应力分布规律研究

    Study on in-situ stress distribution law of multi-coal seams mining in Wuhai Mining Area

    • 摘要: 为揭示乌海矿区地应力场分布规律及其主要控制因素,科学评估矿区工程地质稳定性,为煤矿安全高效开采及灾害防控提供科学依据,本文采用水压致裂法对乌海矿区中六座典型煤矿内的共计19个测点进行了原位地应力测量,并对实测地应力数据进行分析,深入探讨了地应力分布特征。研究结果表明:乌海矿区中的地应力分布受到构造应力的显著影响,σHσhσv类型和σHσvσh类型的测点数量一致,均为9个,而仅有一个测点的垂直应力大于水平应力;水平主应力方向以NW向为主导,只有公乌素煤矿的水平主应力方向为NE向。乌海矿区中的大部分区域都属于低应力区,其次为中应力区,没有发现高应力区和超高应力区分布。此外,主应力值与埋深之间在总体上呈现出一种线性关系,随着埋深增加,水平应力增幅要大于垂直应力;侧压比的数值主要集中在1~2之间,埋深和平均侧压比间的关系式与Hoek-Brown提出的关系式形式一致,但具体数值不同。最大剪应力的范围为0.13~2.91 MPa,整体而言,随着测点深度的增加,最大剪应力呈现出一种递增的趋势,主应力差值比的数值主要集中在0.3~0.4的范围内,反映了水平应力各向异性程度。研究结果为理解乌海矿区地应力状态及其影响因素提供了重要实证,对于该区域煤矿巷道支护设计优化、冲击地压等动力灾害风险评估及防治具有直接的工程指导意义。

       

      Abstract: To reveal the distribution patterns of the in-situ stress field and its primary controlling factors in the Wuhai Mining Area, scientifically evaluate the stability of engineering geological conditions, and provide a scientific basis for safe and efficient coal mining as well as disaster prevention and control, this study employs the hydraulic fracturing method to conduct in-situ stress measurements at 19 measurement points across six typical coal mines within the Wuhai Mining Area. The measured stress data are analyzed to thoroughly explore the characteristics of the in-situ stress distribution. The results indicate that the in-situ stress distribution in the Wuhai Mining Area is significantly influenced by tectonic stress. The number of measurement points exhibiting the stress pattern σHσhσv equals that of points showing σHσvσh, with nine cases each. Only one measurement point records vertical stress exceeding horizontal stress. The dominant orientation of the maximum horizontal principal stress is NW-trending, with the Gongwusu Mining Area being the sole exception where it displays an NE-trending orientation. The results demonstrate that the majority of the Wuhai Mining Area falls within the low-stress zone, followed by the medium-stress zone, with no high-stress or extremely high-stress zones identified. Furthermore, the results reveal a general linear relationship between principal stress magnitudes and burial depth. As the burial depth increases, the increase in horizontal stress is greater than that of vertical stress. The lateral pressure coefficient predominantly ranges between 1 and 2. While the functional form of the relationship between burial depth and the average lateral pressure coefficient aligns with Hoek-Brown’s proposed formulation, the specific numerical values differ. The maximum shear stress ranges from 0.13 MPa to 2.91 MPa, exhibiting an overall increasing trend with measurement depth. The principal stress difference ratio is primarily concentrated within the 0.3-0.4 range, reflecting the degree of horizontal stress anisotropy. These findings provide crucial empirical evidence for understanding the in-situ stress state and its controlling factors in the Wuhai Mining Area. They offer direct engineering guidance for optimizing coal mine roadway support design and preventing dynamic hazards such as rockburst in this region.

       

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