沟埋式涵洞非线性土压力试验研究与数值模拟

现行公路桥涵设计通用规范中线性土压力理论未能准确反映沟埋式涵洞涵顶垂直土压力变化规律,土压力计算结果与实际情况存在差异,导致涵洞在施工或使用过程中出现不同程度的病害。结合现场试验和数值模拟研究了沟埋式涵洞垂直土压力的变化规律,以及涵顶填土内部的土拱效应,分析了涵顶平面土压力及不均匀沉降的分布规律。研究结果表明,并非所有沟埋式涵洞涵顶垂直土压力都小于按线性土压力理论计算结果,它与填土高度、沟谷宽度、沟谷坡角、涵洞几何尺寸、填料性质及地基刚度等因素有关,涵顶垂直土压力随各影响因素呈非线性变化。填土达到一定高度后,涵顶填土内部产生土拱效应,该效应能够缓解涵顶应力集中现象,但其具有不稳定性。沟埋式涵洞的设计与施工应综合考虑各因素对涵洞受力状态的影响。

Experimental investigation and numerical simulation of nonlinear earth pressure for trench-buried culverts

The variation of vertical earth pressure on trench-buried culverts was not accurately reflected by the linear earth pressure theory in the prevailing Chinese General Code for Design of Highway Bridges and Culverts.The calculated results using the code method were different from the practical situations,which might induce various problems in the construction process or in service time of culverts.So the variation of vertical earth pressure and soil arching effect in fill for culverts installation were studied based on the field experiments and FEM numerical simulation.Meanwhile,the distribution of earth pressure and differential settlement at the elevation of culverts top were analyzed.It was shown that the vertical earth pressure on the top of trench-buried culverts was not always less than the calculated result of the linear earth pressure theory,and it increased nonlinearly with the influential factors,such as the height of embankment fill,the width of trenches,the slope angle of trenches,the geometric size of culverts,the characteristics of fill and the elastic modulus of ground.When the fill on the culvert reached a certain height,soil arch was generated.The soil arching effect could release the stress concentration on the top of culverts,but it is instable.The influence of these factors on the stresses of trench-buried culverts should be comprehensively considered in the design and construction procedure.