Research on the mechanism of the spewing in the EPB shield tunnelling

The key to success in Earth-Pressure-Balanced(EPB) shield is converting the muck excavated from the cutter face to the plastic soil,or the spewing occurs usually and harmfully.In this paper,the relation model of water pressure and flow is built to explain the spewing mechanism.And consequently,the critical conditions of the spewing are put forward.The sensitivity of the parameter influencing the spewing is analyzed.At last,the possibility of spewing was analyzed for the engineering projects of four cities.