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废弃矿井压氢储能硐室潜在破裂面及其控制

Potential damage surfaces and their control in abandoned mine caverns for compressed hydrogen energy storage

  • 摘要: 对废弃矿井大巷进行改造并用于压氢储能是实现废弃资源二次利用的有效方式和实现“双碳”目标的重要途径。受采动作用影响,废弃矿井大巷通常处于非等压状态,而非等压会降低硐室储能的可靠性。基于此,首先依据断裂过程中的剪切能量释放特性,建立了考虑气体压力、温度和剪切能量释放演化的相场断裂模型,并对该模型进行验证;其次依据提出的相场模型,对不同煤柱宽度和水平差下硐室潜在破裂面的起裂和发育特征进行研究;最后将提出的相场断裂模型与实际工程相结合,对不同围岩处理方式下的处理效果和起裂诱因进行研究。结果表明:所提出的相场断裂模型可以较好的描述硐室潜在破裂面起裂位置、起裂诱因和发育过程;煤柱的宽度直接影响硐室的起裂压力,煤柱越宽硐室起裂压力越大,且破裂面整体以剪切为主;硐室的破裂面分为主破裂面和次破裂面,煤柱宽度越大,次破裂面发育越深;硐室与采场的水平差同样影响硐室起裂压力,随着硐室与采场水平高度差增大,硐室围岩起裂压力先增大后减小,且破裂面出现由张拉应力引起的分叉现象;在对潜在破裂面进行止裂研究后表明,增打底部锚杆是提升硐室储氢性能最为有效的改造方法,其次为围岩进行注浆强化,进行采空区充填效果较弱;在采用锚杆索加强支护下的硐室起裂诱因为剪切应力,破裂面沿锚杆发育诱因为张拉应力。

     

    Abstract: Retrofitting abandoned mine shafts and using them for compressed hydrogen energy storage is an effective way to reuse waste resources and to realize the “double carbon” strategy. Due to mining action, abandoned mine shafts are usually in a non-isobaric state, and the non-isobaric state reduces the reliability of energy storage in the chambers. Based on the shear energy release characteristics during the fracture process, a phase-field fracture model considering the evolution of gas pressure, temperature and shear energy release was developed and validated; secondly, based on the proposed phase-field model, the initiation and development of potential fracture surfaces of chambers with different widths of coal pillars and level differences were investigated; and lastly, the proposed phase-field fracture model was combined with actual projects to investigate the effect of different treatment methods on the potential fracture surfaces of chambers. Finally, the proposed phase-field fracture model was combined with the actual project to investigate the effect of the treatment and fracture triggers under different surrounding rock treatment methods. The results show that the proposed phase-field fracture model can better characterize the fracture initiation location, fracture triggers and development process of the potential fracture surface of the chamber; the width of the coal pillar directly affects the fracture initiation pressure of the chamber; the wider the coal pillar, the higher the fracture initiation pressure of the chamber, and the overall fracture surface is mainly shear; the fracture surface of the chamber is divided into primary fracture surface and secondary fracture surface, and the wider the width of the pillar, the deeper the secondary fracture surface develops; the level difference between the chamber and the mining site also affects the fracture initiation pressure of the chamber; the fracture initiation pressure is also influenced by the level difference between the chamber and the mining site. The difference between the level of the chamber and the quarry also affects the fracture initiation pressure. As the height difference between the chamber and the quarry increases, the fracture initiation pressure of the perimeter rock increases and then decreases, and the fracture surfaces appear to be bifurcated due to tensile stresses; the fracture stopping study of the potential fracture surfaces shows that the most effective way to improve the hydrogen storage performance of the chamber is to add more anchors at the bottom of the chamber, followed by grouting to strengthen the perimeter rock and the weak effect of filling in the void areas. The cause of fracture in the chamber with the anchor ropes was shear stress, and the cause of fracture development along the anchors was tensile stress.

     

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