厚表土斜井冻结凿井期井壁混凝土应变实测研究

Study on concrete strain of inclined shaft lining in deep alluvium during freezing sinking period

为了研究斜井冻结法凿井过程中井壁结构的安全性,对哈密大南湖十号煤矿主斜井进行了现场实测,获得了主斜井冻结段井壁混凝土应变和钢筋应力的变化规律。结合混凝土极限拉压应变,分析了井壁结构的安全性,并对斜井冻结施工提出优化建议。研究表明:井壁浇筑后,混凝土应变变化可分为4个阶段,即紊乱期、应变加速增长期、应变缓慢增长期及应变稳定期,井壁真实应变应从紊乱期后开始计算;斜井井壁设计主要受拉应变控制;在大南湖十号煤矿主斜井施工中,井壁底板环向拉应变最大达1 280με,远大于混凝土设计极限拉应变,井壁圆弧段局部位置环向拉应变超过200με,井壁处于破裂危险状态。

For the purpose of studying the safety of inclined shaft lining in the period of freezing sinking, variations of concrete strain and steel stress of shaft lining have been carried out based on in-situ measurement of main inclined shaft in Hami Large South Lake mine. The structure safety of shaft lining has been discussed by taking ultimate concrete tensile and compressive strain into account, besides which, several optimized suggestions have been put forward. The result has shown that variations of concrete strain could include four periods： disordered period, accelerated increasing period, slow increasing period and stable period, and the valid concrete strain should be taken into account after disordered stage. The design of inclined shaft lining should mainly be controlled by concrete tensile strain. During the construction of main inclined shaft of Hami Large South Lake mine, the maximum hoop tensile strain of floor has been up to 1 280 με, which is considerably greater than the ultimate tensile strain value, and the maximum hoop tensile strain of circular section has exceeded 200 με with the shaft lining facing the conditions of fracturing.