Abstract:

The Zhangji Mining Area is located in the crack fractured zone and with rich water. The ground surface pregrouting of auxiliary shaft No. 2 is difficult. Hence, the construction technology of ground surface pregrouting is studied based on engineering geological investigation, technical design and industrial experiment. A series of technologies, i.e., freezing construction of upper strata, pregrouting of lower bedrock, and vertical boreholes and Yshaped boreholes combined layout method, are adopted, which leads to simultaneous construction of grouting, freezing and shaft sinking and shortening of construction period. Meanwhile, realtime monitoring has been realized and key grouting parameters have been obtained by using selfdeveloped monitoring device. The construction effect is estimated by pressurized water test. The monitoring results show that: 1) The final grouting pressure value and grouting quantity can meet the design standards, and the total grouting quantity was 16 286 m3. 2) The permeability coefficient of formation decreased obviously and the residual water inflow of the mine shaft is 2.27 m3/h obtained from the pressurized water test, which proves the rationality and efficiency of the abovementioned method in terms of reinforcement and water stopping.

Key words: shaft, water inrush, ground surface pregrouting, triple simultaneous construction, monitoring technology