Abstract For tunnelling in a stratum that contains both high and low water levels, the EPB/slurry dual-mode shield machine is used, in order to ensure both safety and economic efficiency of underwater shield tunnel construction. In practical works, however, switchover between the two modes can be often irrational and subjective, so the dualmode shield machine cannot be used to its full efficiency. In this paper, the shield tunnel from Baotai Avenue to Changhong Square, a rail transit project of Ziyang Metro, is used as the example. First, the principle and basis for switchover between the slurry and EPB modes is determined through theoretical analysis. Then the blowout calculation model is improved, and three-dimensional finite element modeling is conducted by using COMSOL Multiphysics,so as to obtain the methods that are used to quantitatively calculate and identify the blowout risk of EPB shield machine and the effects that are generated by the relevant parameters of the screw conveyor. As the results indicate: According to field verification, blowout can be viewed as the principle for identifying the rational switchover point. The improved blowout model is clearly superior to the previous models in terms of the rational switchover point of the two modes, for it can be used to more accurately identify the risk range of the EPB mode and to guide mode switchover of dual-mode shield machine in a safe, economically efficient and rational manner. The difference between the result of the improved theoretical formula and that of the three-dimensional simulation calculation is no more than 30% and both results exhibit similar variation pattern. The pore water flow rate of screw conveyor is in positive correlation with the cylinder diameter and screw pitch of the screw conveyor and in negative correlation with the diameter of screw shaft and length of screw conveyor.
Abstract：
For tunnelling in a stratum that contains both high and low water levels, the EPB/slurry dual-mode shield machine is used, in order to ensure both safety and economic efficiency of underwater shield tunnel construction. In practical works, however, switchover between the two modes can be often irrational and subjective, so the dualmode shield machine cannot be used to its full efficiency. In this paper, the shield tunnel from Baotai Avenue to Changhong Square, a rail transit project of Ziyang Metro, is used as the example. First, the principle and basis for switchover between the slurry and EPB modes is determined through theoretical analysis. Then the blowout calculation model is improved, and three-dimensional finite element modeling is conducted by using COMSOL Multiphysics,so as to obtain the methods that are used to quantitatively calculate and identify the blowout risk of EPB shield machine and the effects that are generated by the relevant parameters of the screw conveyor. As the results indicate: According to field verification, blowout can be viewed as the principle for identifying the rational switchover point. The improved blowout model is clearly superior to the previous models in terms of the rational switchover point of the two modes, for it can be used to more accurately identify the risk range of the EPB mode and to guide mode switchover of dual-mode shield machine in a safe, economically efficient and rational manner. The difference between the result of the improved theoretical formula and that of the three-dimensional simulation calculation is no more than 30% and both results exhibit similar variation pattern. The pore water flow rate of screw conveyor is in positive correlation with the cylinder diameter and screw pitch of the screw conveyor and in negative correlation with the diameter of screw shaft and length of screw conveyor.
ZHANG Ruyue1 ZOU Fuqing2 FANG Yong1 GENG Fangchuang2 ZHUO Bin1 WANG Yubo1
.Study on Rational Switchover Point of EPB/Slurry Dual-mode Shield Based on the Improved Spewing Model[J] MODERN TUNNELLING TECHNOLOGY, 2024,V61(1): 125-136
2024, Vol. 61 