Abstract: To investigate the primary factors influencing segment uplift during shield tunneling, particularly the effect of grout properties on segment uplift, a load-sensing measurement structure for segment uplift is designed, and a visualized model test system is independently developed. The structural safety and functional feasibility of the system is verified through numerical analysis and water injection tests, and the system′s measurement error for uplift force on the segment is determined. The results reveal the following: (1) The change in uplift load on the segments during grouting is linearly related to the grout volume, with R² values exceeding 93%. The average linear rate of change in uplift load is 62.6% of the theoretical value, with a difference of 28.79 N/cm compared to theoretical calculations. (2) Grease in the floating seal chamber inhibits segment uplift, generating resistance equivalent to approximately 41.1% of the theoretical uplift load. The maximum deviation between the actual and theoretical uplift loads is approximately 2.1%, indicating that the system accurately simulates the force conditions of segment uplift. (3) The cross-sectional load growth rate initially decreases and then increases as the grout volume changes. The transverse displacement constraint of the segments effectively controls horizontal displacement caused by overturning loads on the segments.

Key words: shield tunneling, segment uplift, model test system, grouting, uplift load