Construction Technology of Shield Tunnel Crossin...
Due to the continuous development and application of large diameter slurry shield technology，the stability of excavation face in large-scale construction has aroused widespread concern in the engineering field.It is worth noting that the large-diameter slurry pressurized shield faces the following risks and problems in the construction of water area（river，lake and sea）crossing the channel section：the stability control of the excavation face is difficult，the splitting instability of the mud breakdown soil layer，the sand gushing and water gushing，the shield overexcavation，the tunnel floating and the segment damage.This makes maintaining the stability of excavation face become the top priority to ensure the safe and smooth construction of the tunnel under the conditions of special sections（punching section）.The stability of the excavation face is achieved by balancing the water pressure and soil pressure of the stratum by the slurry pressure acting on the impermeable cement film.Therefore，the properties of the slurry and the mud film should be strictly controlled in the construction.This chapter compares and selects two construction schemes of shield crossing the middle channel section of the Yangtze River，analyzes the stability of excavation face through theoretical calculation and experimental simulation，and puts forward the method of selecting tunneling parameters and risk management countermeasures in engineering，which has important reference value for guiding practical construction.