Abstract The shield tunnelling of Guangzhou Metro Line 18 is faced to such characteristics as complex ground dis? tribution, large strength differences between soft and hard rocks, and dense residential building complex located above the tunnel. In view of this, it is intended to address two major problems in actual construction, i.e. settling the reasonable tunnelling parameters and controlling the settlement deformation of buildings on the ground surface through a series of active measures, such as grouting reinforcement, on-site dynamic monitoring, and optimization of tunnelling parameters. The results show that: (1) in this type of soft and hard rock interbedded strata, tunnelling parameters (such as torque and thrust) would fluctuate greatly when the cutterhead passes through the geological boundary of different strata, and the total thrust would be in a fine correlation with the torque, where it is appropriate to control the tunnelling parameters at certain values, i.e. the thrust at 30 000～35 000 kN, the torque at 4 500～6 000kN·m, and the advancing speed at 35～45 mm/min; (2) the proposed technological process of multi-section sealing and advanced grouting in the tunnel can lift the ground surface by 3～5 mm within the scope of 18 m in front of the cutterhead, with maximum lifting value of 9.02 mm, while it can also mitigate the settlement tendency of the soil mass induced by shield driving and subsequent consolidation and stabilization; (3) temporary shield stoppage caused by tool wear, large fluctuation in tunnelling parameters, and the jamming of the screw conveyor can cause the daily settlement rate of the buildings on the surface to exceed 3 mm/d. The adoption of advanced grouting in tunnel and the clay shock method ahead of the preset machine stop point can effectively alleviate the settlement tendency and control the daily settlement rate below 2 mm/d during the hyperbaric intervention of the earth chamber; (4) the settlement of the surface buildings near the left and right tunnel axes can be basically divided into three phases of slight heave—large settlement—gradual stabilization, with maximum settlement of -21.38 mm and -22.49 mm respectivly, being less than the control values.
Abstract：
The shield tunnelling of Guangzhou Metro Line 18 is faced to such characteristics as complex ground dis? tribution, large strength differences between soft and hard rocks, and dense residential building complex located above the tunnel. In view of this, it is intended to address two major problems in actual construction, i.e. settling the reasonable tunnelling parameters and controlling the settlement deformation of buildings on the ground surface through a series of active measures, such as grouting reinforcement, on-site dynamic monitoring, and optimization of tunnelling parameters. The results show that: (1) in this type of soft and hard rock interbedded strata, tunnelling parameters (such as torque and thrust) would fluctuate greatly when the cutterhead passes through the geological boundary of different strata, and the total thrust would be in a fine correlation with the torque, where it is appropriate to control the tunnelling parameters at certain values, i.e. the thrust at 30 000～35 000 kN, the torque at 4 500～6 000kN·m, and the advancing speed at 35～45 mm/min; (2) the proposed technological process of multi-section sealing and advanced grouting in the tunnel can lift the ground surface by 3～5 mm within the scope of 18 m in front of the cutterhead, with maximum lifting value of 9.02 mm, while it can also mitigate the settlement tendency of the soil mass induced by shield driving and subsequent consolidation and stabilization; (3) temporary shield stoppage caused by tool wear, large fluctuation in tunnelling parameters, and the jamming of the screw conveyor can cause the daily settlement rate of the buildings on the surface to exceed 3 mm/d. The adoption of advanced grouting in tunnel and the clay shock method ahead of the preset machine stop point can effectively alleviate the settlement tendency and control the daily settlement rate below 2 mm/d during the hyperbaric intervention of the earth chamber; (4) the settlement of the surface buildings near the left and right tunnel axes can be basically divided into three phases of slight heave—large settlement—gradual stabilization, with maximum settlement of -21.38 mm and -22.49 mm respectivly, being less than the control values.
ZHANG Bangchao1 LIU Hongliang2 LEI Fengguo2 PENG Guanghuo2
.On Settlement Control in Large-diameter EPB Shield Tunnelling under Civil Housing Complex in Upper-soft and Lower-hard Strata[J] MODERN TUNNELLING TECHNOLOGY, 2022,V59(2): 172-181
2022, Vol. 59 