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大直径救援井安全透巷技术研究

Study on safe tunneling penetration technology for large diameter rescue wells

  • 摘要: 透巷井段是指在救援井施工过程中,为防止上覆岩层出水进入巷道,并保障套管下入、固井时孔底动压力不对巷道顶板造成破坏,井底预留一定厚度的地层。为了实现安全、迅速提升被困人员到地面,要求救援井井径大、优快钻进、精确中靶,同时保持巷道顶板的完整性、控制泥浆涌入巷道。通过理论分析、数值模拟、现场应用等研究手段,优化了救援井透巷施工工艺。通过三维相似模拟,对巷道开挖顶板位移、钻进过程围岩扰动、透巷井段安全距离、套管下深进行研究,同时对空气潜孔锤反循环钻进工艺进行优化,有效封隔含水层及井壁不稳定地层,保证救生舱在救援井下放、提升顺利。以山西某煤矿避难硐室地面救援井为例,建立了巷道开挖、钻进过程数值模拟模型,模拟结果表明:① 巷道和钻孔围岩岩体破坏的主要方式包括剪切破坏和拉伸破坏,且以剪切破坏为主,地层岩石黏聚力越小,围岩塑性破坏区宽度越大。巷道开挖后顶板塑性区高度达到9.59 m,顶板最大下沉量为15.9 cm。② 地面大直径救援井钻进过程中,钻井破坏了地层原有应力平衡,引起周围地层的应力重新分布,造成周围地层产生移动变形和塑性破坏区,且以井眼中心呈对称分布,井壁水平位移的范围为20.3~90.5 mm,塑性破坏区宽度为1.43~1.82 m。③ 施加在井底载荷一定条件下,随着透巷距离的增加,开始巷道顶板有大的拉伸塑性应变,当透巷井段长度增加到15 m以上时,顶板塑性应变减弱,随着透巷距离继续增加,侧帮塑性应变受挤压作用增大。大直径救援井安全透巷技术研究,是对救援井施工工艺技术的进一步完善。

     

    Abstract: The tunneling well section refers to the formation with a certain thickness reserved at the bottom of the well during the construction of the rescue well to prevent the water from the overlying rock strata from entering the roadway, and to ensure that the dynamic pressure at the bottom of the hole does not cause damage to the roadway roof when the casing is inserted and the well is cemented. In order to achieve safe and rapid lifting of trapped personnel to the surface, it is required that the rescue well has a large diameter, excellent and fast drilling, and accurate targeting, while maintaining the integrity of the roadway roof and controlling mud influx into the roadway. Through theoretical analysis, numerical simulation, field application and other research methods, the construction technology of the rescue well penetration roadway was optimized. Through three-dimensional similarity simulation, roof displacement of roadway excavation, surrounding rock disturbance during drilling process, safety distance of through roadway section, and casing depth were studied. At the same time, the air DTH hammer reverse circulation drilling process was optimized to achieve effective packer aquifer and sidewall unstable strata, and ensure that the rescue capsule is placed and lifted smoothly in the rescue well. Taking the ground rescue well in the refuge chamber of a coal mine in Shanxi as an example, a numerical simulation model of the roadway excavation and drilling process was established. The simulation results show that:① the main damage methods of the roadway and the surrounding rock of the borehole include shear failure and tensile failure with the domination of shear failure. The smaller the cohesion of formation rock, the greater the width of the plastic failure zone of surrounding rock. After the roadway is excavated, the height of the roof plastic zone reaches 9.59 m and the maximum roof subsidence is 15.9 cm. ② During the drilling of the large-diameter rescue well on the ground, the drilling destroyed the original stress balance of the stratum, causing the stress redistribution of the surrounding strata, causing the surrounding strata to produce moving deformation and plastic damage zones, which were symmetrically distributed in the center of the wellbore. The range of horizontal displacement is 20.3-90.5 mm, and the width of plastic failure zone is 1.43-1.82 m. ③ Under certain conditions of bottom-hole load, with the increase of the through-way distance, the roof of the roadway has a large tensile plastic strain at first. When the through lane interval length increases to more than 15 m, the roof plastic strain weakens, The roadway distance continues to increase, and the plastic strain of the lateral side increases due to the extrusion effect. The research on the safety penetration technology of large-diameter rescue wells is a further improvement of the construction technology of rescue wells.

     

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