山区公路半填半挖路基沉降控制指标与标准研究

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。

Study of index and criterion for settlement control applicable to cut-and-fill subgrade in mountain-highway

To avoid pavement structure failure induced by subgrade settlement, index and criterion for settlement control applicable to cut-and-fill subgrade for mountain-highways are studied. Firstly, the Prony series expressions for three-dimensional Merchant model are deduced based on constant Poisson’s ratio hypothesis; and the settlement calculation models of cut-and-fill subgrade were established with ABAQUS. The calculations indicate that post-construction settlement curves of cut-and-fill subgrade are spoon-shaped or S-shaped. The difference in curve shape reveals the time-space coupling effect in subgrade settlement. Secondly, the following hypothesis is proposed based on post-construction settlement mechanisms: the post-construction settlement curves of cut-and-fill subgrade are central symmetric S-shaped curves composed of two parabolic segments. The mechanical response of asphalt pavement under parabolic subgrade settlement indicates that the additional flexural-tensile stress is linear with quadratic term coefficient of parabolic equation which, consequently, can be adopted as settlement control index applicable to cut-and-fill subgrade. Finally, the method of defining settlement control criterion applicable to cut-and-fill subgrade is presented based on the failure modes of asphalt pavement under traffic load and subgrade settlement. The research findings provide a technical foundation for post-construction settlement control of cut-and-fill subgrade.