多圈管分期冻结施工法温度场现场实测与分析

Observation and Analysis of the Temperature Field of Host Well Tube Frozen by Stages

在深厚表土中进行冻结法施工常产生由于冻胀应力造成的冻结管断裂,为减小深井冻结壁在形成过程中产生的内部冻胀应力,采取外圈辅助冻结孔滞后于主圈孔冻结的施工方案,能有效地防止冻结管断裂.应用有限元方法对淮南某煤矿主井冻结井筒分期冻结过程进行了瞬态温度场数值模拟,和现场实测十分接近.分期冻结方案能减少冻结壁内部水分聚集,以达到减少冻胀应力的目的,并形成相对比较均匀的温度场.相同冻结条件下采用分期冻结方案,冻结壁有效厚度增大约15%.数值模拟的系统分析可为深井冻结壁的设计与施工提供科学依据.

Broken freezing tubes caused by frost- heave stress are often found in freezing construc- tion of thick overburden. In order to reduce the in- ternal heave stress produced in the forming process of deep shaft＇ freezing wall, the research adopts such a construction plan, in which the addendum circle assistance hole freezing lags behind the host circle hole freezing, which can prevent the freezing tube from break effectively. Finite element method for the freezing process was applied to simulate the transient state temperture fields of a coal mine in Huainan, of which the host well tube was frozen by stages. The simulated results are extremely close to the observed ones. To freeze by stages is able to decrease water aggregation within the fro- zen wall and reduce frost-heave stress, and then a relative uniform temperature field is formed. Un- der the same freezing condition to freeze by stages may cause frozen wall＇s effective thickness about 15% thicker. System analysis of the numerical simulation may provide a scientific basis for design and construction of a deep-well＇s frozen wall.