Grouting lifting effect of shield tunnel differential settlement in soft-hard interbedded strata

A differential settlement control project of an operational shield subway tunnel in Beijing is taken as an example. In order to explore the differential settlement lifting effect of grouting in the tunnel on the soft and hard interbedded strata of silty clay-sandy soil and the deformation law of segments, and to ensure the safety of the structure during construction, the vertical deformations and opening displacements of the track bed structure in the diseased interval before and after construction are monitored. Through the analysis of the regularity of the data, the influence of different grouting positions on the deformation of the segment and the overall uplift of the tunnel structure is studied. The results show that the influence of arch waist grouting on the structure is more significant than that of arch bottom grouting. In the arch bottom grouting stage, the slurry forms a bearing layer at the bottom of the tunnel, and the arch waist grouting has a lifting effect on the structure. Finally, the grouting uplift mechanism in the soft-hard interbedded strata is summarized, the construction monitoring indicators are proposed, and the guiding suggestions for the follow-up treatment plan are provided.