Soil Heterogeneity Effects on Bridge Piles Deformation under Shield Tunnelling Disturbance

This research examines the impact of soil heterogeneity on the bridge piles beneath a nearby tunnel excavation using Monte-Carlo stochastic analysis. Sensitivity analysis is specifically used to the variation of stratum range, variation coefficient (COV), and fluctuation distance of the soil Young’s modulus. Meanwhile, the reliability evaluation approach is also applied to systematically examine the impact of COV on the likelihood of a pile failing. The findings suggest that more consideration should be given to the degree and range of geological parameter variations in the strata surrounding the tunnel. The horizontal and vertical fluctuation distances in this project are predicted to be around 18 m and 4.5 m, respectively. The fluctuation range influences the frequency of low stiffness zones in the soil. Additionally, the variation coefficient has a significant effect on the pile deformation, presenting a positive association. The pile deformation exhibits an increasing tendency in the wake of the growing variation coefficient. More significantly, the increase of the COV will directly lead to a rising failure probability of the pile settlement. According to extensive Monte-Carlo simulation calculations, the simulation results considering the variability of soil parameters have a certain deviation from the deterministic in the perspective of probability statistics. It is quite necessary to attach importance to the soil heterogeneity effects in the pile foundation stability under construction disturbance.