Abstract:
The cross passages of Jinlang running tunnel section of Nanning metro line 3 are mainly located in round gravel stratum which is characterized by poor self-stability, sand gushing, water inflow and deformation caused by large rock disturbance. In view of this, the artificial freezing method is designed for construction of cross passages. The arrangement of freezing holes, selection of freezing parameters and optimization of grouting parameters to control of settlement of soil mass after thawing is described in detail. The temperature of circulated salt water,temperature of soil mass and pore pressure of pressure relief holes are specially analyzed during construction of active freezing, the rules of temperature change of soil mass and formation of frozen wall are summarized, the excavation time of cross passage is accurately judged, and the countermeasures for the problems in freezing construction of cross passage are proposed.