Mechanism and control technology of water inrush from shaft freezing holes after thawing

In order to solve water inrush disaster from shaft freezing holes, based on analyzing the characteristic of freezing sinking technology, stratum condition and water inrush status from freezing holes after thawing in some projects, it is indicated that four reasons result in water inrush. Firstly, water-resisting curtain is failure after stratum thawing; secondly, the stratum penetrability increases around freezing holes; thirdly, the interface adhesion strength is reduced, as a result, the aquifer and aquifuge are connected during freezing holes to form vertical channel for water; fourthly, the high confined water can spurt from weakest part of shaft. Calculating by RFPA^2D-Flow seepage program, the project is workable, and the best radius is 7.50 m to dig circular impermeable tunnel by FLAC^3D. digging circular tunnel at feasible stratum outside shaft and cutting off freezing pipe to grout, then backfilling the circular tunnel to form artificial aquifuge were taken, the quantity of water inrush was reduced from 90m³/h to 2m³/h, and the shaft was steady, reaching the aim of control and prevention of water inrush.