Brief Analysis of Mechanical Mechanism of Earth Pressure Balance Shield Double Screw Conveyor

Brief Analysis of Mechanical Mechanism of Earth Pressure Balance Shield Double Screw Conveyor in Tunnel Construction 

When some earth pressure balance shields are used in some areas with large soil and water pressure, it is difficult to balance the formation pressure by a screw conveyor, and the double-section series screw conveyor is used to solve the earth pressure balance problem. According to the principle of earth pressure balance, it is established. The mechanical model of the double-section tandem screw conveyor is obtained, and the mechanical expression of the bottom pressure of the double-section tandem screw conveyor under static equilibrium is obtained. Based on this, the bottom pressure of the double-section tandem screw conveyor and its equipment parameters are discussed. And the correlation between the properties of the muck and the soil, provide a simple method for rational design, transformation, selection and evaluation of the earth pressure balance shield double-section tandem screw conveyor.

Screw conveyor is one of the important components of earth pressure balance shield earthing system. In the shield construction, the screw conveyor not only has the function of excluding the muck in the excavation chamber, but more importantly, it has the function of controlling the bottom pressure of the screw conveyor, thereby maintaining the earth pressure balance of the shield excavation surface. The geometry, angle and nature of the screw conveyor are important factors in balancing the pressure at the bottom of the screw conveyor. The author has simplified the mechanics of the screw conveyor, and used the principle of earth pressure balance to derive the formula for calculating the bottom pressure of the screw conveyor, and then analyzed the relationship between the bottom pressure of the screw conveyor and the parameters of the conveyor. 

Normally, The earth pressure balance shield can meet the construction requirements with a screw conveyor. However, in some areas where the geological conditions are relatively complicated and the soil and water pressure in the formation is relatively high, a screw conveyor cannot balance the pressure in the cabin, and the double-section tandem screw conveyor is used to balance the earth pressure. Based on the basic principle of earth pressure balance, this paper derives the calculation formula of the bottom pressure of the double-section series screw conveyor.