高压力大流速富水软岩地层冻结技术

Ground Freezing Technology of Watery Soft Rock Strata with High Pressure and High Flow Rate

高家堡煤矿风井深820m,穿越厚度达380m的高水压、大流速深厚富水软岩含水层,最大涌水量达2 219.63m3/h,采用冻结法施工。为了确保冻结封水效果,采用一次冻全深方案,并采用"三大一小"施工方式,即大直径冻结管、大盐水泵、大装机制冷量、小开孔间距。冻结孔采用外、内圈孔插花加防片帮孔的布置方式。冻结初期,快速降低盐水温度,实现了冻结壁早交圈,井筒早开挖。利用部分冻结孔,对深厚含水层裂隙进行注浆充填加固,减小地下水流速,保证了冻结效果。该井筒冻结施工所取得的成功经验,可为西部富水软岩地层冻结法凿井设计和施工提供借鉴。

A mine ventilation shaft in Gaojiapu Mine had a depth of 820 m,was passed through a deep and 380 mthick watery soft rock aquifer with high water pressure and high flow rate,a max inflow in the shaft was 2 219.63m3/h and was constructed with a ground freezing method.In order to ensure a freezing water sealing effect,a full depth freezing plan was applied and a＂three large and one small＂construction method was applied.The construction method was applied with a large diameter freezing tube,large brine pump,large unit refrigerating capacity and small space between the boreholes.A scatter and spalling prevention pattern method was applied to the external and internal ring of the freezing boreholes.At a freezing initial period,a rapid reduction of the brine temperature was conducted and an early cryosphere of the freezing wall could be realized in order to have an early excavation of the mine shaft.Partial freezing boreholes were applied to the grouting and backfill reinforcement of the cracks in the deep and thick aquifer in order to reduce the flow rate of the underground water and to ensure the freezing effect.The successful experiences obtained from the mine freezing shaft construction would provide the references to the design and construction of the mine freezing shaft sinking in the watery soft rock strata in Western China.