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曹家滩煤矿10 m超大采高工作面矿压显现规律及强矿压防治技术

Mine pressure behavior law and strong mine pressure prevention technology of working face of 10 m super large mining height in Caojiatan Coal Mine

  • 摘要: 以曹家滩煤矿122104工作面为背景, 基于矿压、位移、微震等多源监测数据, 系统揭示了10 m超大采高工作面矿压显现规律与强矿压发生机理, 建立了超大采高采场“叠合拱–梁”结构模型, 提出了“主动支撑防护+区域卸压弱化+全方位监测预警”三位一体围岩控制策略。研究结果表明: ①10 m超大采高工作面覆岩周期破断具有动载强来压、顶板下沉速度快、来压持续距离长、支架安全阀开启率高的强矿压显现特征, 工作面顶板周期破断步距10~25 m, 周期来压动载系数平均值1.42, 支架最大下缩量平均0.63 m, 来压期间液压支架安全阀开启率大于50%的占比达48.1%; 来压沿倾向方向呈现区域性聚集特征, 分布于距机头75~250 m范围, 走向方向呈“大小周期”交替来压特征, 大周期来压平均间隔137.5 m; 超大采高工作面开采上覆岩层呈叠合“拱–梁”结构, 中上部厚硬顶板在采空区后方长距悬顶, 导致顶板在工作面前方断裂或在支架后方弯曲下沉, 引发工作面强矿压显现。②减小周期来压步距和持续距离、降低来压支架动载系数、预防煤壁片帮以及避免液压支架压架, 为控制10 m超大采高工作面围岩稳定性的核心要素。③液压支架高初撑力特征有效控制了顶板早期下沉, 高工作阻力特性缓解了煤壁处承载力, 对煤壁大面积片帮及来压期间顶板急速下沉进行了有效抑制, “双层伸缩梁结构配合三级联动护帮装置”, 实现了对支架前方顶板无支护区域及超高煤壁防护作业的协调调控, 有效克服了原有分体式护帮装置煤壁防护覆盖不足的缺陷。④采用5 m3/min大流量水力压裂技术, 通过“一场一策”分区参数设计, 有效弱化了厚硬顶板, 显著降低来压步距与动载系数。⑤利用KJ21矿压实时预警系统, 实现了支架工况与顶板破断动态监测。

     

    Abstract: The successful mining of working face of 10 m ultra-large mining height in Caojiatan Coal Mine marks a new stage for the fully-mechanized mining of extra-thick coal seams. Based on multi-source monitoring data, such as mine pressure, displacement and microseismics, the rules of mine pressure behavior and the occurrence mechanism of strong mine pressure in the 10 m ultra-high mining height working face were studied, and a "superimposed arch-beam" structural model of the ultra-high mining height stope was established. A three-in-one surrounding rock control strategy of "active support and protection + regional pressure relief and weakening + all-round monitoring and early warning" was proposed. The results show that the cyclic breaking of the overlying rock in the 10 m ultra-high mining height working face has the characteristics of strong mine pressure, such as strong dynamic load, fast roof sinking speed, long lasting distance of pressure, and high opening rate of support safety valves. The cyclic breaking of the roof of the working face is 10-25 m, the average dynamic load coefficient of periodic pressure is 1.42, and the average maximum shrinkage of support is 0.63 m. During the pressure period, the proportion of hydraulic support safety valves opening rate was more than 50% is 48.1%. The incoming pressure shows regional aggregation characteristics along the tendency direction, distributed in the range of 75-250 m from the nose. The trend direction shows the characteristics of alternating incoming pressure with "large and small cycles", and the average interval between large cycles is 137.5 m. The overlying rock strata of the ultra-high mining face are in a superimposed "arch-beam" structure, and the thick and hard roof in the middle and upper parts overhangs the roof behind the goaf for a long distance, causing the roof to break in front of the face or bend and sink behind the support, causing strong mine pressure appears in face. Reducing the step distance and continuous distance of periodic weighting, reducing the dynamic load coefficient of weighting support, preventing coal wall spalling and avoiding the crushing of hydraulic support are the core elements to control the stability of surrounding rock in 10 m ultra-large mining height working face. The high initial supporting force characteristics of the hydraulic support effectively control the early subsidence of the roof, the high working resistance characteristics relieve the bearing capacity of the coal wall, inhibit the large-area spalling of the coal wall and the rapid subsidence of the roof during pressurization effectively. The double-layer telescopic beam structure of the hydraulic support is combined with the three-level linkage protection device, which realizes the coordinated control of the unsupported area of the roof in front of the support and the protection operation of the ultra-high coal wall, and effectively overcomes the defects of the insufficient protection coverage of the coal wall of the original split protection device. The 5 m3/min high-flow hydraulic fracturing technology, employing a "one-field-one-strategy" zonal parameter design, effectively weakens the thick hard roof, leading to a significant reduction in weighting intervals and dynamic loading coefficients. The real-time warning system of KJ21 mine pressure achieves dynamic monitoring of support operating conditions and roof fracturing.

     

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