Field test insights on mechanical behavior of ground around a large deformed shield tunnel rehabilitated by grouting

At present, light-disturbance grouting technology has been widely applied in controlling and rehabilitating the transverse deformation of existing shield tunnels. However, there is a lack of corresponding research on the stratigraphic mechanical response during the light-disturbance grouting process. This paper relies on a case study of transverse deformation rehabilitation of shield tunnels treated with light-disturbance grouting in Shanghai. A lining ring was selected as a test ring at the site, with pressure sensors installed on both sides of the grouting hole to monitor the variations in earth pressure and pore water pressure. Based on this, the variations of the additional earth pressure, excess pore water pressure, and effective stress near the grouting hole during the grouting process were analyzed. Furthermore, the mechanical response of the ground at the test location induced by the grouting process of three adjacent grouting holes was further analyzed. On this basis, the slurry distribution coefficients in the existing grouting efficiency equations were corrected in conjunction with the additional earth pressure variations during grouting, and this provided a new idea for quantitatively characterizing the uncertainty of the grouting body in a two-dimensional plane and the design of grouting parameters in engineering practice.