地下水位下降对井壁破坏的影响

THE INFLUENCE OF GROUNDWATER LOWERING ON THE SHAFT WALL RUPTURE

  • 摘要: 淮北某些矿区井筒变形、破坏严重,其主要诱发因素是下含水层水位下降而产生的附加应力。运用2D-σ软件进行了数值模拟认为:由于地下水位下降,地层与井筒发生相对位移而产生剪应力,其大小与水位降深和相对位移成正比;轴向应力随深度变化小,而随下含水层水位下降而增大;井壁破坏首先发生在其内缘,并逐渐向外扩展,破坏度沿深度方向增大;一含和下含同时有水位降时,轴向应力和剪应力的变化与单一含水层水位下降时相似,但轴向应力变化幅度明显增大,剪应力在上部含水层处增加。模拟计算分析结果与淮北地区井壁变形、破坏情况大体一致。

     

    Abstract: In Huaibei the shafts are deformed and ruptured heavily in some mining areas,the main inducing factor of which is the additional stress formed by the water lowering in the lower aquifer.The numerical modeling calculation and analysis are conducted using the [2D-σ] software.It is considered that the shearing stress is produced by the relative displacement between stratum and shaft due to the groundwater lowering,its size is directly proportional to the water level drawdown and relative displacement;the change of axial stress is not apparently with depth but largely with the water lowering in the lower aquifer;the shaft wall rupture occurres firstly on its internal margin,then expanded progressively outward,and the rupture degree is increased along the depth direction;when the water lowering is occurred simultaneously in both No.1 and lower aquifers,the variation regularities of axial stress and shearing stress are similar to that during the water lowering in the single aquifer,but the variation amplitude of axial stress is increased obviously;and the raise of shearing stress is occurred in the upper aquifer.The abovementioned results of modeling calculation and analysis are conformable basically to the shaft wall deformation and rupture in Huaibei mining area.

     

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