Calculation and factors for distribution of initial distribution of peak value of excess pore water pressure due to shield construction

Based on the stress relief theory and the stress transfer theory, a formula for the peak value of the excess pore water pressure at any point induced by shield construction is deduced. Case studies show that the distribution of the peak value of the excess pore water pressure around shield lining is similar to a circular shape. With the increase of the distance from the central axis of shield tunnel, the peak value of the excess pore water pressure decreases in a concave curve. The effect of shield diameter is opposite to the depth of the shield tunnel on the peak value of the pore water pressure of the soil. The isopleth map of the peak value of the excess pore water of the soil changes fastest at the bottom of the shield tunnel , but it increases gradually at the top of the shield tunnel. At a certain depth, the largest peak value of the excess pore water pressure is above the tunnel axis, and it decreases with the increase of the distance away from the axis. With the increase of the depth, the maximum value of the peak value of the excess soil pore water has an increasing trend.