Ground surface deformation induced by grouting construction of shallow-buried shield tunnels in mudstone strata

Grouting is widely used to mitigate ground surface deformation during shield tunneling. However, the quantitative influence of grout solidification and hardening on deformation and its prediction remains insufficiently understood. This work investigates how time-dependent grout solidification and hardening affect ground deformation. It combines analytical solutions with numerical simulations. The time-dependent evolution of grout properties is incorporated into both approaches for shallow-buried shield tunneling in mudstone strata. Results show that explicitly simulating grout solidification yields larger settlement than neglecting it. Compared with the instantaneous setting case (0 h), an initial setting time of 4 h increases the maximum surface settlement by 59%. The grout hardening rate plays a decisive role in deformation control. Theoretical analyses further indicate that the shield tail, rather than the cutterhead, is the critical reference location governing deformation development.