Abstract In order to achieve fast and efficient excavation of earth pressure balanced shield, the influencing fac? tors of the main tunnelling parameters of the shield are researched and the intrinsic relationship between the foam agent parameters and shield tunnelling parameters is analyzed based on the shield construction of the Wetland Park station -Wuyuanwan station running tunnel of Xiamen Metro Line 2, Lot 3. Through lab proportioning tests of four foam agents and in combination with field tests, the effects of foam agent concentration, gas-liquid ratio and foam injection ratio on the internal friction angle and bulk density of the improved soils are studied. The results show that when the concentration of the foam agent increases by 1%, the internal friction angle of the soils decreases by about 2.43°; the influence degree of each parameter of foam on the cutterhead torque is foam concentration > foam flow rate > expansion rate, and the influence degree on shield thrust is foam concentration > expansion rate > foam flow rate, with foam concentration having the greatest influence on both tunnelling parameters. When the parameters of the foam system are changed to improve the tunnelling condition, it is preferred to select the foam concentration,which has a significant linear relationship with the tunneling parameters, so as to control the shield thrust and cutterhead torque to a reasonable range, to ensure the safe and smooth tunnelling of the shield. For each 1% increase in foam concentration during the construction of the project, the average reduction in shield thrust is about 1,710 kN and that in cutterhead torque is about 316 kN?m.
Abstract：
In order to achieve fast and efficient excavation of earth pressure balanced shield, the influencing fac? tors of the main tunnelling parameters of the shield are researched and the intrinsic relationship between the foam agent parameters and shield tunnelling parameters is analyzed based on the shield construction of the Wetland Park station -Wuyuanwan station running tunnel of Xiamen Metro Line 2, Lot 3. Through lab proportioning tests of four foam agents and in combination with field tests, the effects of foam agent concentration, gas-liquid ratio and foam injection ratio on the internal friction angle and bulk density of the improved soils are studied. The results show that when the concentration of the foam agent increases by 1%, the internal friction angle of the soils decreases by about 2.43°; the influence degree of each parameter of foam on the cutterhead torque is foam concentration > foam flow rate > expansion rate, and the influence degree on shield thrust is foam concentration > expansion rate > foam flow rate, with foam concentration having the greatest influence on both tunnelling parameters. When the parameters of the foam system are changed to improve the tunnelling condition, it is preferred to select the foam concentration,which has a significant linear relationship with the tunneling parameters, so as to control the shield thrust and cutterhead torque to a reasonable range, to ensure the safe and smooth tunnelling of the shield. For each 1% increase in foam concentration during the construction of the project, the average reduction in shield thrust is about 1,710 kN and that in cutterhead torque is about 316 kN?m.
ZHANG Xun1 HE Xiongfei2,
3
.Study on the Effect of Foam Agent on the Main Tunnelling Parameters of Earth Pressure Balanced Shields[J] MODERN TUNNELLING TECHNOLOGY, 2021,V58(3): 176-181
2021, Vol. 58 