Study on the Generalized Displacement Boundary and Its Analytical Prediction for Ground Movements Induced by Shield Tunneling

Abstract

The process of shield tunnel excavation would inevitably cause surrounding ground movement, and excessive displacement in the soil could lead to large deformation and even collapse of the tunnel. The methods estimating convergence deformation around tunnel opening is summarized. Then, a universal pattern of displacement boundary condition around the tunnel cavity is originally introduced, which is solved as the combination of three fundamental deformation modes, namely, uniform convergence, vertical translation, and ovalization. The expression for the above-mentioned displacement boundary condition is derived, by imposing which the analytical solution for ground movements, based on the stress function method, is proposed. The reliability and applicability of this proposed solution are verified by comparing the observed data in terms of surface settlement, underground settlement, and horizontal displacement. Further parametric analyses indicate the following: (1) the maximum settlement increases linearly with the gap parameter and the tunnel radius, while it is negatively related to the tunnel depth; (2) the trough width parameter is independent of the gap parameter and the radius, while it is proportional to the tunnel depth. This study provides a new simple and reliable method for predicting ground movements induced by shield tunneling.

Pressure Model Study on Synchronous Grouting in Shield Tunnels Considering the Temporal Variation in Grout Viscosity

“…When the thickness of the shield tail void reaches the threshold value, its effect on the grout pressure is limited. However, some studies have shown that a larger thickness of the shield tail void leads to larger ground settlement [44]. Therefore, the thickness of the shield tail void should be appropriately designed before tunnel construction to avoid extreme ground settlement.…”

“…On the other hand, the maximum ground settlement increases with the tunnel radius [44]. During the construction of large-diameter tunnels, the initial grout injection pressure needs to be increased to provide sufficient grout pressure and control ground settlement.…”

Study on the construction deformation of a slotted shield in loess tunnels with different buried depths and large sections

“…The horizontal deformation and deformation rate of the surrounding rock at the arch waist and arch foot increased sharply with the vicinity of the excavation face. During the excavation of the cross section, the horizontal deformation of the surrounding rock at the arch waist and foot is constrained, and the decrease of the horizontal deformation rate of the surrounding rock is due to the presupporting effect of the insertion of the shield shell on the excavated soil (Ye et al, 2017;Zhou, et al, 2019;Fang et al, 2021;Tang, et al, 2021). As the shield tail is far away from the research section, the support of the shield shell disappears, resulting in a sharp increase in the horizontal deformation of the surrounding rock Cao et al, 2021).…”

The Construction Countermeasures of Shallow‐Buried Small Spacing Tunnel Undercrossing Cultural Relic Buildings: A Case Study

“…As for the underpass construction of nearby existing sensitive buildings, domestic and foreign scholars have carried out a wealth of research work in the field monitoring [3,4], numerical simulation [1,5,6], theoretical analysis [7][8][9][10], and other aspects. For example, Wang [11] studied the advantages and disadvantages of the underpassing scheme of jacking frame culvert and the underpassing scheme of shallow-buried tunnels in the project of Shanxi Yushen Expressway underpassing the Qin Great Wall ruins and pointed out that the shallow-buried underexcavation method can effectively restrain the deformation of the surrounding rock.…”