Surface Pre-grouting and Freezing for Shaft Sinking in Aquifer Formations

摘要

Special techniques are used for shaft sinking in aquifer formations. In the unstable aquifer formations encountered in Chinese coal mines, freezing is always adopted for shaft constructions in an aquifer alluvium, while surface pre-grouting is generally adopted in bedrock formations. So far, freezing has been used to construct 500 vertical shafts, comprising a total length of 80 km, and surface pre-grouting has been used in more than 150 vertical shaft sinking projects. The maximum depth of freezing is about 700 m, while the maximum depth of surface pre-grouting exceeds 1000 m.