Abstract In practical engineering, the ability to prevent blowout is low for the large diameter screw conveyor.
Blowout occurs from time to time when shield machine passes through the section with high water and soil pressure.A model of pressure bearing characteristics of soil plug is established to analyze the bearing capacity of soil plug.Taking a large-diameter screw conveyor of a shield used in Chengdu Metro as a reference, a simulated analysis on muck transportation process of a screw conveyor with equal or variable pitch is conducted through changing pitch of screw blade by discrete element simulation method. The simulation results show that: the movement velocity of soil mass in the soil plug section decreases by about 15.1% compared with the axial velocity in the soil intake section,and the total velocity decreases by about 6.7%; good soil plug can be formed in soil plug section in condition of variable pitch, and a design of screw blade with variable pitch can be used as a new means of shield tunnelling to prevent blowout; the design of variable screw pitch increases the wear in soil plug section, increases the force applied
on screw shaft, the starting torque and the peak torque by about 20-40 kN, 21.5% and 28.6% respectively, therefore, it is necessary to increase the strength of screw blade and output torque of the screw conveyor with variable screw pitch.
Abstract：
In practical engineering, the ability to prevent blowout is low for the large diameter screw conveyor.
Blowout occurs from time to time when shield machine passes through the section with high water and soil pressure.A model of pressure bearing characteristics of soil plug is established to analyze the bearing capacity of soil plug.Taking a large-diameter screw conveyor of a shield used in Chengdu Metro as a reference, a simulated analysis on muck transportation process of a screw conveyor with equal or variable pitch is conducted through changing pitch of screw blade by discrete element simulation method. The simulation results show that: the movement velocity of soil mass in the soil plug section decreases by about 15.1% compared with the axial velocity in the soil intake section,and the total velocity decreases by about 6.7%; good soil plug can be formed in soil plug section in condition of variable pitch, and a design of screw blade with variable pitch can be used as a new means of shield tunnelling to prevent blowout; the design of variable screw pitch increases the wear in soil plug section, increases the force applied
on screw shaft, the starting torque and the peak torque by about 20-40 kN, 21.5% and 28.6% respectively, therefore, it is necessary to increase the strength of screw blade and output torque of the screw conveyor with variable screw pitch.
MI Shipeng
.Research on Soil Plug Pressure-bearing Characteristics of Screw Conveyor with Variable Pitch[J] MODERN TUNNELLING TECHNOLOGY, 2020,V57(4): 119-126
2020, Vol. 57 