Calculation of shield tunnel uplift induced by synchronous grouting

This paper analyzes the combined effects of grout properties (mix ratio, viscosity), construction speed, grouting pressure, bolt preload, and tunnel slope on shield tunnel uplift induced by synchronous grouting. A finite-difference model incorporating 12 consecutive segments was developed, incorporating time-dependent grout parameters (static buoyancy, viscosity) fitted via exponential functions. Field tests conducted on Ningbo Rail Transit Line 8, along with 3D-printed segment experiments, confirmed model reliability. Results show that grout with a shorter initial setting time minimizes uplift, while faster construction speeds increase the magnitude of uplift. Higher bolt preload reduces uplift by enhancing joint stiffness, whereas grouting pressure has a negligible influence. The uphill tunnel slope exacerbates uplift while the downhill slope mitigates it, providing practical guidelines for slope-specific construction protocols.