袁大滩矿主斜井冻结壁温度及冻结压力研究

Study on frozen wall temperature and freezing pressure of main inclined shaft in Yuandatan Mine

以袁大滩矿主斜井冻结法凿井施工为工程背景,计算得出冻结壁顶部和两侧的外荷载分别为1.53MPa和1.17MPa,利用FLAC 3D建立斜井冻结壁数值模拟模型,研究井筒施工一个6m掘砌段长后,冻结壁温度随时间的变化规律以及冻结压力的分布规律。结果表明:新浇筑外层井壁产生的水化热,使井壁壁后冻土产生融化,且回冻困难,需要采取积极冻结措施;冻结壁顶板冻结压力峰值约为2.1 MPa,两帮冻结压力峰值约为1.6 MPa,均大于冻结壁外载,冻结压力在井筒轴向分为压力降低区、升高区和稳定区,冻结壁顶部塑性区范围比两帮大,井筒顶板容易发生破壁事故。

Taking main inclined shaft construction of Yuandatan Mine using freezing method as engineering background, the external loads on the top of frozen wall and on the sides were 1.53 MPa and 1.17 MPa. The numerical simulation model of in- clined shaft frozen wall was built by FLAC 3D, andthe distribution laws of frozen wall temperature and the freezing pressure on the outer wall were studied after the construction of a 6 m excavating section length. The results showed that the hydration heat generated by the new pouring outer wall melt frozen soil behind the outer wall, and the refreezing was difficult, so the strength- ened freezing action was needed. The peak freezing pressure of frozen wall roof was about 2. i MPa, and two sides was about 1.6 MPa, bigger than the external loads of frozen wall. The freezing pressure was divided into pressure reduction zone, elevation zone and stability zone in the inclined shaft axial direction, and the plastic zone at the top of frozen wall was larger than that of two sides, so the roof was more prone to wall breaking accident.