Influence of Pile Foundation Construction on Health Trend of Adjacent Shield Tunnel Structures

To study the impact of deep bridge pile construction in soft soil areas on the health status of adjacent operating tunnel segments, a spatiotemporal distribution statistical comparison and data joint attribution analysis method were used. Segment cracks mainly arise and develop with the development of structural tension area, mainly longitudinal cracks in the waist, and the data variability and dispersion degree of the number of cracks are higher than the representative width. The extrusion effect of deep and large foundation piles in adjacent tunnels was generated, which controlled the development of the horizontal diameter difference of the segment, and the crack growth of the tunnel segment close to the foundation pile construction was weaker than that of the distant pile tunnel. The number of new cracks was positively nonlinear with the horizontal distance of the pile tunnel, and the increment of the number of cracks in the segment can be estimated. The horizontal diameter difference can be used to predict and prevent new cracks in the segment. The recommended threshold is 20 mm for the first layer and 38 mm for larger values of concern.