Study on the Influence of Grouting Pressure Volatility on the Additional Response of Adjacent Pile Foundation in Shield Construction

It has been proved that numerical simulation is an effective method when simulating the shield tunneling, and analyzing and evaluating the influence of the construction process on the adjacent pile foundation. During shield construction, the parameters of soil along the heading direction have spatial variability, so the grouting pressure needs to be adjusted constantly to ensure the stability of ground stress. This causes the grouting pressure to fluctuate around the design pressure/curve during construction. Therefore, the influence of the volatility of grouting pressure parameters on the adjacent pile foundation should be considered in the process of simulating shield tunnel. Considering the volatility of grouting pressure parameters, the influence of the additional response of the adjacent pile foundation during the shield construction of subway tunnel is analyzed by numerical simulation method in combination with the shield construction case of 'Xuefue Street Station-Changfeng Street Station' of Taiyuan Metro Line 2. The results show that when considering the volatility of grouting pressure, the process of shield tunneling has a great influence on the additional bending moment of the adjacent pile foundation, but it has a relatively small influence on the additional axial force. The maximum influence on the additional bending moment is within the range of 0~25 m below the ground (within about 2.5 times the depth of the tunnel), and the maximum influence on the additional axial force is near the buried depth of the tunnel. Chi-square test shows that when the grouting pressure of 300 groups meets the normal distribution, the additional axial force and additional bending moment of the loaded pile foundation are also subject to the normal distribution.