路面对路基强度及不均匀沉降的力学响应研究

Study on Mechanical Response of Pavement Structure to Subgrade Strength and Subgrade Differential Settlement

路基强度和不均匀沉降对路面结构附加应力影响显著,是影响路面结构服役性能和使用寿命的重要因素,工程建设中,路面铺筑条件对路基沉降提出了要求。针对雄安新区高速公路长寿命路面结构形式,采用有限元数值模拟手段,定量和定性地分析了路基强度和路基不均沉降对路面结构附加应力的影响。研究结果表明:底基层层底受最大拉应力,路面表层受最大压应力,且均随着路基差异沉降的增加持续增大;当差异沉降范围内曲线过渡时,差异沉降率标准不具备普适性,在差异沉降率一定条件下,层底拉应力随着差异沉降范围的增加而逐渐减缓趋稳;路基路面接触模式对路面结构受力影响显著,当路基路面完全黏结接触时,路面结构底基层附加拉应力随路基模量的增加而增大,当路基路面完全光滑接触时,路面结构底基层附加拉应力不受路基模量的影响;路基路面完全黏结接触和路基路面完全光滑接触构建了路面结构受力分析的上、下限,根据现场路基模量、差异沉降范围和路面材料强度参数,提出可引起路面结构底基层层底拉裂的差异沉降率理论范围为0.29%~0.38%。该研究成果能够为提出满足高质量建设要求的路基强度标准和路基不均匀沉降标准提供理论依据。

The strength and the uneven settlement of highway subgrade have a significant impact on the mechanical response of pavement structure,and then affects the service performance and life of pavement.For the construction of pavement structure,it requires the subgrade settlement satisfy some settlement criteria.In this paper,the specific influence of subgrade strength and uneven settlement on the mechanical response of long life pavement structure in Xiong an New Area is quantitatively and qualitatively analyzed by means of finite element numerical simulation.The results show that the maximum tensile stress on the bottom of the subbase layer and the maximum compressive stress on the surface of the pavement both increase with the increase of subgrade differential settlement;when the differential settlement domain is described by a curve,the calculated differential settlement rate criterion is not universal for the settlement domain with different size.Specifically,with a certain differential settlement rate,the tensile stress at the bottom of subbase gradually slowly decreases and becomes stable with the increase of the subgrade differential settlement domain.When the subgrade and subbase are completely rough contacted,the tensile stress of the subbase of the pavement structure increases with the increase of the subgrade modulus.When the subgrade and the subbase are absolutely smooth contact,the tensile stress of the subbase of the pavement structure is not affected by the subgrade modulus.Therefore,the upper and lower limits of the tensile stress of the pavement structure are correspondingly obtained by the two ideal contact conditions.The theoretical range of differential settlement rate for this project,which may cause tension cracking of the subbase of pavement structure,is proposed as 0.29%~038%.The research results can provide theoretical bases for setting control criteria of subgrade strength and differential settlement that meet the requirements of high-quality construction.