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为考察软基上埋式箱涵受力特性,通过离心模型试验,研究了其竖向和侧向土压力、土压力系数随填土高度变化的规律及周围填土位移场的变化情况。试验结果表明,使用桩基的箱涵与两侧路堤产生了显著的差异沉降,并在涵洞处形成了驼峰;内外土柱差异沉降在路堤中形成了拱脚位于涵顶两侧的上凸压力拱,并使拱脚处竖向土压力集中,且竖向土压力系数随路堤填筑呈开口向下的抛物线分布,在某一涵顶路堤高度下达最大值;同时,随涵顶路堤填筑,涵洞侧向土压力和侧向土压力系数增加,由于涵侧路堤以沉降为主的位移模式与挡土墙后填土不同,涵洞侧向土压力小于现行规范值。软基上路堤、涵洞和地基的协同作用分析表明,传统的强涵基、弱地基的设计理念将使涵顶竖向土压力集中,并导致结构失效。为降低涵洞结构破坏风险,建议采用轻质填料填筑涵顶、涵洞反开挖施工和结构设计考虑涵顶竖向土压力集中等措施。
In order to investigate the mechanical properties of buried box culvert on soft foundation, the vertical and lateral earth pressure, the law of earth pressure coefficient with filling height and the change of surrounding filling displacement field were studied by centrifugal model test. The test results show that the box culvert and the embankment on both sides of the pile have significant differential settlement and formed hump at the culvert; the differential settlement of the soil column inside and outside forms upward convex pressure in the embankment on both sides of the culvert Arch and the vertical soil pressure at the arch foot is concentrated, and the vertical earth pressure coefficient is parabolic with the downward opening of the embankment filling, reaching the maximum value at the height of a certain culvert embankment. At the same time, with the culvert embankment filling , The lateral earth pressure and the lateral earth pressure coefficient of culverts increase. Because the displacement pattern of the main culvert embankment is mainly different from the backfill of retaining wall, the lateral earth pressure of culvert is less than the current normative value. The synergetic analysis of embankments, culverts and foundations on the soft foundation shows that the traditional design concept of strong foundation and weak foundation will cause the vertical earth pressure on the culvert to be concentrated and lead to structural failure. In order to reduce the risk of damage to the culvert structure, it is suggested to adopt lightweight packing to fill culverts, anti-excavation of culverts and structural design to consider such measures as concentration of vertical earth pressure at culverts.