考虑侧向刚柔边界约束的黄土填方路基沉降计算方法

Calculation method of settlement in loess-filled subgrade considering lateral rigid-flexible boundary constraints

提出一种新的考虑刚柔边界约束和侧向变形的黄土填方路基沉降计算方法。基于自主研发的三向加载设备和室内压缩试验,分析不同竖向加载方式和不同侧向约束对土体竖向及侧向变形的影响,提出考虑土体压实度和围压的边界影响系数,建立压实黄土侧向应变模型,给出考虑刚柔边界条件和侧向变形的黄土路基沉降计算方法。研究结果表明:边界影响系数与路基压实度和围压都呈正相关,且刚柔约束边界对黄土压缩性指标的影响程度最高能达到40%。提出的竖向和三向边界影响系数综合考虑了路基压实度、侧向围压以及边界条件的影响。利用工程实例验证了新模型计算方法的准确性和实用性,提高了传统分层总和法的精度。

The new settlement calculation method in loess-filled subgrade considering rigid-flexible boundary constraints and lateral deformation was proposed.The effects of different vertical loading methods and lateral constraints on the vertical and lateral soil deformation were analyzed by the self-developed three-dimensional loading equipment and compression tests.The boundary influence coefficient considering soil compaction and confining pressure was proposed,and the lateral strain model of compacted loess was established.The settlement calculation method of loess subgrade considering boundary conditions and lateral deformation was proposed.The results show that the boundary influence coefficient is positively correlated with the subgrade compaction degree and confining pressure.And the influence of rigid-flexible constraints on the compressibility index of loess can reach 40%at most.The proposed vertical and three-way boundary influence coefficients consider the effects of subgrade compaction,lateral confining pressure,and boundary conditions.The accuracy and practicability of the settlement calculation formula of loess subgrade considering different boundary conditions and lateral deformation are verified by engineering examples,which improves the accuracy of the traditional layered summation method.