蒙陕矿区内钢板-钢筋混凝土钻井井壁非均匀受力特性研究

Study on non-uniform stress characteristics of steel plate-reinforcedconcrete drilling shaft wall in Inner Mongolia and Shaanxi mining area

以蒙陕矿区某煤矿风井为工程背景,利用双向不等压模型推导出水平地应力下井壁的受力形式,并得出了非均匀系数k的计算公式,确定了蒙陕矿区地层的不均匀系数范围为0.06~0.20,研判了钻井井壁全深受力关键横断面的受力破坏特征。根据有限元软件ANSYS模拟非均匀荷载条件下的井壁受力规律,井壁混凝土外缘环向应力为控制应力,井壁应力呈现非均匀分布,90°位置的不均匀程度大于0°位置,外荷载较小的90°位置受拉,而外荷载较大的0°位置受压。通过对井壁压力试验台对内钢板-钢筋混凝土进行非均匀加载试验分析,非均匀荷载对钻井井壁受力影响极为明显,在k=0.15时模型的峰值应力仅为均匀荷载条件下的23.1%~33.3%;在k=0.20时模型的峰值应力为均匀荷载条件下的20%左右,且破坏形式为混凝土先受拉破坏,随后钢筋和钢板屈服。研究结果表明,内钢板-钢筋混凝土钻井井壁对非均匀荷载较为敏感,在蒙陕矿区使用钻井法应该考虑非均匀系数的影响,且需要在井壁设计阶段重点关注井壁外荷载较小位置的受力。

Taking the eastern air shaft of a mining area in Inner Mongolia and Shaanxi as the engineering background,the stress form of the shaft wall under horizontal in-situ stress was derived by using the two-way unequal pressure model,and the calculation formula of non-uniformity coefficient k was obtained.The range of non-uniformity coefficient of strata in Inner Mongolia and Shaanxi mining area was 0.06~0.20,and the dangerous section of full depth of shaft was determined.The ANSYS software is used to simulate the stress of the shaft wall under non-uniform load conditions.The results show that the circumferential stress of the outer edge of the shaft wall concrete is the control stress,and the stress of the shaft wall is non-uniformly distributed.The degree of non-uniformity at the 90°position is greater than that at the 0°position.The 90°position with smaller external load is pulled,while the 0°position with larger external load is compressed.The non-uniform loading of the two cross-section models was carried out by using the shaft wall test bench.The results show that the non-uniform load has a very obvious influence on the stress of the drilling shaft wall.When k=0.15,the peak stress of model 1 is only 23.1%~33.3%of that under uniform load.When k=0.2,the peak stress of model 1 and model 2 is about 20%of that under uniform load,and the failure mode is that the concrete is first damaged by tension,and then the steel bar and steel plate yield.The results show that the inner steel plate-reinforced concrete drilling shaft wall is more sensitive to non-uniform load.The influence of non-uniform coefficient should be considered when using drilling method in Inner Mongolia and Shaanxi mining area,and it is necessary to pay attention to the stress at the position where the load outside the shaft wall is small in the design stage of the shaft wall.