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针对山区公路路基拓宽改建的特殊性,运用非线性有限元法,开展衡重式挡土墙修建、新路基逐层分步填筑的动态施工力学行为数值模拟。针对新路基是否加筋、加筋层位以及衡重台上下方新路基填土压实状况的差异性,对新旧路基稳定安全性、滑动面形态、沉降、挡土墙变位等力学响应的影响开展参数敏感性分析。结合室内模拟墙体不同主动位移模式下拓宽路基土工离心模型试验成果,考察新旧路基顶面沉降与挡土墙变位的动态耦合关系。在山区公路路基拓宽改建动态施工中,挡土墙的变位和新旧路基顶面沉降、差异沉降相互耦合,呈正相关关系。衡重台下方新路基填土压实不足会导致新旧路基顶面差异沉降增大。挡土墙主动外倾诱发新旧路基顶面产生较大附加(差异)沉降,宜对新路基自重压密作用造成的差异沉降予以适当修正放大后进行上承路面结构设计。
Aiming at the particularity of widening and reconstruction of mountain highway subgrade, the nonlinear finite element method is used to carry out the numerical simulation of dynamic construction mechanics behavior of the construction of the counterweight retaining wall and the new embankment sub-step by step. In view of the difference of whether the new subgrade is reinforced, the reinforced layer and the compaction status of the new subgrade above the counterbore, the mechanical response to the stability of the old and new roadbed, the shape of the sliding surface, the settlement, the displacement of the retaining wall and so on Influence Parameter sensitivity analysis. Combined with the test results of broaden the centrifugal model tests of subgrade under different active displacement modes of indoor simulation wall, the dynamic coupling relationship between the settlement of top and bottom of old and new subgrade and the displacement of retaining wall are investigated. In the dynamic construction of widening and rebuilding of highway subgrade in mountainous area, the displacement of retaining wall and the settlement of top and bottom surface of old and new subgrade and the differential settlement are positively correlated with each other. The lack of compaction of new embankment under the counterbalanced platform will lead to the increase of differential settlement of the top surface of new and old subgrade. The active camber of retaining wall induces large additional (differential) settlement on the top surface of old and new roadbed. It is appropriate that the differential settlement caused by the compaction of new roadbed should be properly amended and enlarged to carry out the structural design of the upper pavement.