浅议软土地区路桥过渡段质量控制指标

Discussion on quality control index of abutment in soft soil areas

现行公路和城市道路规范对软土区路桥过渡段的质量要求主要基于道路等级确定路基的容许工后沉降,在质量控制时未充分考虑公路与城市道路设计速度的影响,未明确路桥过渡段长度及渐变率,也未明确桥台处错台高度,导致部分软土区路桥过渡段出现陡坡型、错台型等影响行车安全的病害形式。结合路桥过渡段安全性、舒适性及车路协同研究成果,分析了公路和城市道路各等级道路与设计速度的关系,并对设计速度进行定档分级,提出基于设计速度的质量评价体系,有效整合了公路和城市道路规范的相关要求。为保证路桥过渡段质量控制指标的延续性,承继了现行规范中路桥过渡段容许工后沉降指标要求并进行优化;将路线规范中的超高渐变率引入路桥过渡段,以确定满足行车安全的渐变率;通过容许工后沉降和渐变率计算出过渡段长度,并引入最大错台高度控制“桥头跳车”。路桥过渡段采用基于设计速度的多指标质量控制,可为科学、合理确定桥头段软基处理方案提供依据,也有利于软土区路桥过渡段的整体质量控制。

The quality requirements of current highway and urban road specifications for the transition section of road and bridge in soft soil areas are mainly based on the road grade to determine the allowable post-construction settlement of the roadbed.However,the influence of the design speed of highways and urban roads is not fully considered.The length and gradient rate of the transition section of road and bridge is not specified.And the abutment staggering height at the abutment is not clear,resulting in steep slope,abutment staggering and other forms of diseases that affect the driving safety in the transition section of road and bridge in soft soil areas.Combined with the research results of safety,comfort and vehicleroad coordination in the transition section of road and bridge,the relationship between various grades of road and design speeds of highway and urban roads is analyzed,and a quality evaluation system based on design speed is proposed.The relevant requirements of highway and urban road codes are integrated.To ensure the continuity of the quality control index of the road-bridge transition section,the requirements of the allowable post-construction settlement index of the road-bridge transition section in the current specification are adopted and optimized.The superelevation gradient rate in the route specification is introduced into the road-bridge transition section to determine the gradient rate that meets the specfic driving safety.The length of the transition section is calculated by allowing the post-construction settlement and gradient rate.The maximum abutment staggering height is introduced to control the“bump at bridge-head”.The multi-index quality control based on the design speed is adopted in the road-bridge transition section,which can provide a scientific and reasonable basis for determining the soft foundation treatment scheme of the bridge head section,and is also conducive to the overall quality control of the road-bridge transition section in the soft soil areas.