In the top process, the pressure in the earth warehouse and the spiral conveyor are used to drain the soil to balance the groundwater pressure and soil pressure. The discharged soil can be dry soil with little water content or mud with more water content. The discharged soil or mud does not require secondary treatment such as mud and water separation.
Soil pressure balance top pipe digger is generally used for pipeline construction of medium and large diameter; Can work normally under relatively shallow soil cover, the shallowest soil cover depth is only 1 times the outer diameter of the digger, which is not possible for other forms of top pipes; The suitable soil has a wide range and is an all-soil top pipe digger; The stability of the excavated surface can be maintained, and the deformation of the ground can be minimal; Easy to operate and safe.
The disadvantage is that due to the discontinuity of the excavation and the grouting pressure generated by the grouting reduction, the pressure of the soil pressure balance top pipe on the soil around the pipeline is very large; The horizontal displacement of deep soil caused by soil pressure is large; In the construction of gravel layer and sand layer with low clay content, the soil body must be improved by additives.

   2019/12/6