中文摘要：

结合杭甬高速铁路上虞北站深厚软土地基处理加固工程,开展典型路基断面桩筏复合结构长期工作特性的现场试验研究,测试获得筏板变形、地基沉降、桩顶反力、筏板钢筋应力及筏板下土压力随时间的变化规律。研究结果表明：桩筏复合结构可以满足深厚软基高铁无砟轨道工后沉降控制要求;筏板沉降沿路基横向呈现中心大、边缘小的分布形式,桩顶反力则沿筏板横向呈边缘大、中间小的马鞍形分布;铺轨6月后,筏板的累计工后沉降仅为0.48 mm,边缘处桩顶反力约为平均桩顶荷载的1.41倍、中心处桩顶反力约为平均桩顶荷载的0.75倍;筏板与其下的地基之间存在接触压力,且沿筏板横向呈抛物线型分布,大约承担30%上部荷载。

英文摘要：

Combined with the deep soft soil foundation treatment and reinforcement project of Shangyu north station of Hangzhou—Ningbo high-speed railway, long-term field tests for behaviors of pile-raft composite structure of typical subgrade section were carried out. The change rules with time of raft deformation, soil settlement, pile top load, steel stress of raft and earth pressure under raft were obtained by test. The results show that pile-raft composite structure can control post-construction settlement of high-speed railway ballastless track in deep soft soil. The distribution of the raft settlement along transverse direction of subgrade presents large in center and small in margin, while the reaction force of pile top is saddle shaped in the transverse direction of raft. In six months after track-laying, the total post construction settlement of raft is only 0.48 mm, the pile top reaction at the edge is about 1.41 times of the average pile top load, and the pile top reaction at the center is about 0.75 times of the average pile load. The contact pressure between raft and foundation soil is distributed along transverse direction of the raft in a parabolic type, and approximately 30% of the upper load is undertaken by the foundation soil.