Load bearing characteristics of a new support structure for rapid repair of damaged tunnels and related field tests.

To address the need for rapid repair and emergency support of traffic capacity in damaged tunnels, this study proposed a new structure combining arches assembled from steel plates and shotcrete with high early strength and performance (hereinafter referred to as the steel-shotcreting structure) based on the concept of "modular assembly, rapid formation, and temporary-permanent combination". It is designed to replace the traditional cast-in-place concrete arch repair technique. Based on the principle of equivalent stiffness, the load borne by the steel arches in the new support structure was analyzed.

Investigating the influence of excavating a tunnel undercrossing an existing tunnel at zero distance.

In urban areas with limited underground space, the new tunnel construction introduces additional loads and displacements to existing tunnels, raising serious safety concerns. These concerns become particularly pronounced in the case of closely undercrossing excavation at zero-distance. The conventional elastic foundation beam model, which assumes constant reaction coefficients for the subgrade, fails to account for foundation loss.

Modified stochastic medium prediction model for the deformation response of concealed underground stations under existing pipelines.

The underground pipeline network in the city is so intertwined that the concealed excavation of a metro station inevitably leads to a series of underground pipelines, causing settlement deformation and further risk of leakage. The existing theoretical methods for analysing settlement deformation are mostly for circular chambers, whereas metro stations have a nearly square cross-sectional form and different construction methods are very different, which have a greater impact on the deformation of the overlying pipelines. In this paper, based on the random medium theory and Peck's formula, the improved random medium model for predicting ground deformation is modified, the correction coefficients λ and η for the influence of different construction methods are proposed, the prediction model of underground pipeline deformation under different construction methods is obtained, and the numerical models of four work methods commonly used in urban tunnel construction: pillar hole method, side hole method, middle hole method and Pile-Beam-Arch (PBA) method are constructed through simulation, and the mathematical analysis software was used to fit the results to the model and obtain the range of correction coefficients λ and η for each of the four methods, and the accuracy and applicability of the theoretical model was verified by combining with actual engineering cases.