Long-term monitoring and analysis of the longitudinal differential settlement of an expressway bridge–subgrade transition section in a loess area

Abstract

To solve the problem of "bridgehead bumping" in the transition section between the road and bridge of an expressway in a collapsible loess area, a lime–soil compaction pile composite foundation is used for the first time in the transition section between the road and bridge of an expressway in China; the loess subgrade is improved by adding lime, and the subgrade is arranged in a multilayer geogrid for the joint treatment of various engineering measures. At the same time, a new type of precision differential pressure settlement meter is used to monitor the long-term settlement of a bridge–subgrade transition section with a small settlement magnitude after the joint treatment, and the distribution characteristics and variation laws of the settlement along the longitudinal direction of the line are obtained. The results show that the effect is better and the differential settlement is smaller when using a lime–soil compaction pile composite foundation; lime improves the loess subgrade backfill, and the multilayer geogrid addresses the bridge–subgrade transition in the collapsible loess area. The differential settlement and settlement rate of the subgrade and abutment increase with increased monitoring time, and the differential settlement increases gradually, while the growth rate decreases gradually and finally tends to be stable. The differential settlement of the transition section is predicted and analysed by using a hyperbolic curve, exponential curve and their combination in a prediction model, and the prediction analysis shows that the combined prediction model has the best prediction effect. These research results can provide guidance and reference for the design and construction of subgrade structures similar to the wet transition section between roads and bridges.

Multi-data settlement prediction along a road section integrating InSAR and coastal subsurface information with data assimilation

“…Studies on road settlement often rely on a qualitative analysis of monitoring data (e.g. Yu et al, 2013a;Mazzanti, 2017;Polcari et al, 2019;Du et al, 2022). These studies assess settlement and its variance along road infrastructures and describe potential associations relations with subsurface architecture or human interventions, such as additional loading and engineering works.…”

In Situ Investigation of the Dynamic Response and Settlement in the Expressway Culvert–Subgrade Transition Section Using a Vibration Exciter

“…It is imperative to underscore that both theoretical analysis and numerical simulations must be grounded in field testing, with their results necessitating comparison and validation to bestow engineering practicality [27]. This imperative arises from the fact that fieldtest investigations offer the most objective and realistic portrayal of the working state within the embankment [28]. Numerous studies have been undertaken concerning field tests conducted in railway-sector transition sections.…”