Establishment of seismic design standards for filling embankments including precast arch culverts

箱式涵至今已广泛应用于路堤填筑下的道路和水流中，但由于其具有经济效益和力学效益的优点，其适用性越来越强，随着交通量的增加，箱式涵的施工机会也在不断增加；然而，拱涵是一种由预制混凝土构件组成的路堤填筑结构，即拱顶、侧墙和仰拱。拱涵结构的一个重要特点是由于预期水平路基反力，它可以灵活地表现出来。然而，由于这种预制拱涵洞最初是为了抵抗恒活荷载而开发的，因此在地震活跃的日本应用该系统时，验证预制拱涵洞系统达到的程度是一个重要的考虑因素。本文采用动力有限元分析方法，对箱涵与箱涵的地震稳定性进行了对比研究，并对地震条件下的拱涵进行了讨论。根据研究结果，得出以下结论：1)箱涵附近的最大剪切应变大于拱涵，受结构形状和刚度的影响。2)弯矩-轴向力关系中，箱涵部分处于受拉状态时弯矩超过M_u，拱涵部分未发生破坏。(3)拱涵拱面与填土路堤结构均发生沉降，而箱涵拱面由侧墙刚度引起差异沉降。4)这种沉降很可能是结构与土间剪应力增大的原因。

Box culverts have been used fir road and water flow under filling with embankment until now However, the applicability of arch culverts is increasing because they have advantages which are of economical and mechanical benefit The chance of construction of arch culverts is increasing according to the increase of traffic amount Box culverts are constructed by cast in place ; nevertheless, arch culvert is an embankment filling structure made of precast concrete members, namely, the vault side walls and invert An important characteristic of the arch culvert structure is that it can behave flexibly due to expecting horizontal subgrade reaction. However since this precast arch culvert was originally developed to resist dead and live loads, verification of the degree of attained with the precast arch culvert system was an important consideration in applying the system in Japan, a seismically active country.In this study, dynamic FEM analysis has been carried out to investigate the seismic stability of an arch culvert comparing to that of a box culvert, and arch culvert under seismic conditions has been discussed The following conclusions centre drawn based on the results of this study :1) The maximum of shear strain adjacent the box culvert is larger than the arch culvert which is affected by shape and rigidity of structure.2) In the relation of moment-axial force, the moment is exceeded M_u when the part is on tensile state in the box culvert, on the other band, the failure is not occurred in cam of the arch culvert.3) It is observed that in cam of the arch culvert, uniform settlement with the structure with filling embankment occurs, however, differential settlement was by stiffness of side walls in the cam of box culvert.4) Such a settlement is likely to be a mason for the increase of shear stress between structure and soils.