基于数值模拟的轻质土路桥过渡段差异沉降分析

Analysis of Differential Settlement in Lightweight Soil Road-Bridge Transition Sections Based on Numerical Simulation

摘要: 路桥过渡段桥头跳车问题日益凸显成为软土地区高速公路建设的难题。其根本在于解决路桥过渡段的差异沉降。泡沫轻质土作为一种解决路桥过渡段差异沉降的优秀轻质路基填料，面临轻质土台背结构型式不统一、目标密度如何选等问题。基于此，本文基于数值模拟，提出路桥过渡段标准施工工序，从轻质土材料、过渡段结构型式、路基高度和施工期时间四个影响因素出发，以路基容许工后沉降、纵坡率、容许台阶高度三个指标评价路桥过渡段差异沉降。通过研究发现，施工期时间对路基表面工后沉降影响非常大，路基高度、轻质土材料密度对路基表面工后沉降有较大影响，路桥过渡段的基底长度和台阶坡度对路基表面工后沉降影响较小，而轻质土材料的模量对路基表面工后沉降基本无影响。所以在路基填筑高度一定的情况下，可通过合理安排施工期的时间、选择合适的轻质土密度，使路基表面工后沉降能够满足规范要求。

Abstract: The issue of vehicles jumping at bridge approaches in transition sections is becoming increasingly prominent, posing a challenge for highway construction in soft soil areas. The root cause lies in addressing the differential settlement in the road-bridge transition sections. Foam lightweight soil, as an excellent lightweight subgrade filling material to solve the differential settlement in road-bridge transition sections, faces issues such as the lack of uniformity in lightweight soil backfill structural types and how to select target density. Based on this, this paper proposes standard construction procedures for road-bridge transition sections through numerical simulations. It analyzes four influencing factors: lightweight soil material, transition section structural type, subgrade height, and construction period. Three indicators—allowable post-construction settlement of the subgrade, slope rate, and allowable step height—are used to evaluate the differential settlement in road-bridge transition sections. The study found that the construction period has a significant impact on the post-construction settlement of the subgrade surface. Subgrade height and the density of lightweight soil materials also greatly influence the post-construction settlement, while the base length and steep slope of the road-bridge transition section have a smaller effect. The modulus of the lightweight soil material has almost no effect on the post-construction settlement of the subgrade surface. Therefore, under a certain subgrade height, reasonable scheduling of the construction period and selection of appropriate lightweight soil density can ensure that the post-construction settlement of the subgrade surface meets the regulatory requirements.