采场等效孔模型及主应力旋转规律

Research on stope equivalent hole model and rotation law of principal stress

  • 摘要: 针对采场侧方巷道非对称破坏现象严重、巷道周边主应力旋转规律不明确的问题,基于主应力方向旋转下的非等压圆孔塑性区边界方程和蝶形破坏理论,阐述了巷道周围主应力旋转与巷道非对称破坏之间的联系。建立采场等效孔的理论模型,研究了不同初始侧压系数下采场侧方主应力方向旋转的演化规律,以神东布尔台矿22205工作面为工程背景,通过理论分析与数值模拟,沿推进方向对采场的不同位置进行等效孔拟合,验证了采场等效孔模型的可靠性,为采场侧方主应力旋转角度的确定提供了一种新思路。研究结果表明:① 当巷道处于蝶形风险区时,其周围主应力方向的旋转会引起蝶形塑性区的旋转,对巷道稳定性造成影响。提供了采场等效孔的理论模型可用于计算采场侧方主应力的旋转角度,数值模拟结果与理论计算吻合度较高。② 采场前后一定范围内的侧方煤体中主应力方向会发生旋转,主应力的旋转角度由采场未开挖时周围的初始地应力与采场等效孔半径决定。当初始侧压系数大于1时,最大主应力由垂直方向逐渐旋转为水平方向, 可以用主应力旋转45°隐性方程对采场侧方旋转45°的位置进行判定;当初始侧压系数小于1时,最大主应力由垂直方向先向水平方向旋转一定角度,随后会回转至垂直方向。采场等效孔半径表征采场的影响范围,半径越大则采场的影响范围越大。

     

    Abstract: Aiming at the problems of serious asymmetric damage phenomenon of roadway on the side of stope and unclear rotation law of principal stress around roadway, the relationship between the rotation of principal stress around roadway and the asymmetric damage of roadway is expounded based on boundary equation of plastic zone around non-isobaric circular hole under the rotation of principal stress and butterfly failure theory. A theoretical model of stope equivalent hole is established to study the evolution laws of the rotation of stope lateral principal stress under different initial lateral stress coefficients. Under the engineering background of the 22205 working face in the Buertai Colliery, equivalent hole fitting is carried out for different positions of stope along the advancing direction. The reliability of the stope equivalent hole has been proved through theoretical analysis and numerical simulation, providing a new idea for determining the rotation angle of the principal stress on the side of the stope. The results show that: ① When the roadway is in the butterfly risk zone, the rotation of the principal stress direction around it will cause the rotation of the butterfly plastic zone, which affects the stability of the roadway. A theoretical model of stope equivalent hole is established, which can be used to calculate the rotation angle of stope lateral principal stress. The numerical simulation results are in good agreement with the theoretical calculation. ② The direction of stope lateral principal stress in a certain range before and after the stope will rotate, and the rotation angle of principal stress is determined by the original state around the stope and the equivalent hole radius of the stope. When the initial lateral stress coefficient is greater than 1, the maximum principal stress gradually rotates from vertical direction to horizontal direction, and the hidden equation of principal stress rotation 45° can be used to determine the position of rotation 45° on the side of the stope. When the initial lateral stress coefficient is less than 1, the maximum principal stress first rotates to the horizontal direction by a certain angle from the vertical direction, and then turns to the vertical direction. The radius of stope equivalent hole represents the influence range of stope. The larger the radius, the larger the influence range of stope will be.

     

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