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

ZHAI Suo-guo; ZHANG Xue-ru

Abstract：A mine ventilation shaft in Gaojiapu Mine had a depth of 820m ,was passed through a deep and 380m thick 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 scat‐ter 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.