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为了避免路基沉降导致路面结构破坏,对适用于山区公路半填半挖路基的沉降控制指标和标准进行了研究。首先,基于常泊松比假定,推导了三维Merchant模型的Prony级数表达式,并以ABAQUS为工具建立了半填半挖路基沉降计算模型。计算结果表明,半填半挖路基工后沉降曲线为“勺”形或“S”形,曲线形状的差异揭示了路基沉降的时空耦合效应。其次,基于路基工后沉降机制分析,提出了如下假定:半填半挖路基工后沉降曲线为中心对称的“S”形,对称中心两侧的曲线段为抛物线。通过沥青路面结构对抛物线形路基沉降的力学响应分析,揭示了路面结构附加弯拉应力与抛物线方程的二次项系数a具有线性关系,据此提出采用a值作为半填半挖路基沉降控制指标。最后,基于沥青路面结构在交通荷载和路基沉降共同作用下的破坏模式,提出了半填半挖路基沉降控制标准的确定方法。研究成果为合理控制半填半挖路基工后沉降提供了明确的技术依据。
In order to avoid the subgrade settlement leading to the destruction of the pavement structure, the subsidence control indexes and standards applied to the semi-filled and semi-subgrade excavation of mountainous highway are studied. First, based on the assumption of constant Poisson’s ratio, the Prony series expression of three-dimensional Merchant model is deduced. The settlement calculation model of half-fill and half-dig roadbed is established by ABAQUS tool. The results show that the settlement curve of semi-filled and half-excavated subgrade is “Spoon” or “S” shape, and the difference of curve shape reveals the space-time coupling effect of subgrade settlement. Secondly, based on the analysis of post-construction settlement mechanism, the following assumptions are put forward: The “S” shape of the half-fill and half-cut foundation is the center of the settlement curve, and the curve segments on both sides of the symmetry center are parabola. Through the analysis of the mechanical response of the pavement structure to the pavement settlement, the paper reveals that there is a linear relationship between the additional bending stress of the pavement structure and the quadratic coefficient a of the parabolic equation. Therefore, . Finally, based on the failure mode of asphalt pavement structure under the combined action of traffic load and subgrade settlement, a method to determine the settlement control standard of half-fill and half-cut subgrade is proposed. The research results provide a clear technical basis for the reasonable control of post-construction settlement of half-fill and half-dig subgrade.