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沿海地区分布大量欠固结软土,具有高含水性、高压缩性、低渗透性等特点,修建于此类土体中的大直径超长灌注桩受后期地基土的固结影响较大。为分析大直径桩周土体固结对桩基受力的影响,该文以沿海高速公路(甬台温复线)桥梁桩基为例,应用Abaqus软件,建立填土荷载下桩土相互作用的三维有限元模型。通过数值模拟发现软土地基对桩基础产生负摩擦效应,负摩阻力、下拉荷载随时间的延长不断增大,二者在当土体固结度达到90%以上时趋于稳定,增加了桩基荷载,降低了桩基承载力,导致超长桩的承载性状由摩擦桩转为端承桩;同时中性点位置随土体固结不断下移,固结度达90%以上时基本保持不变。
A large number of underconsolidated soft soil is distributed in the coastal area, which has the characteristics of high water content, high compressibility and low permeability. The large diameter and overlength cast-in-situ bored pile built in such soil is more affected by consolidation of the later foundation soil. In order to analyze the effect of consolidation of large diameter piles on pile foundation, this paper takes the bridge pile foundation of coastal highway (Yongtaiwen double track) as an example. Abaqus software is used to establish the interaction between pile and soil Three-dimensional finite element model. Through numerical simulation, it is found that the soft soil foundation has a negative friction effect on the pile foundation, negative friction resistance and pull-down load increase with time, both of which tend to be stable when the soil consolidation degree reaches more than 90% Base load, the bearing capacity of the pile is reduced, and the bearing behavior of the super-long pile is changed from the friction pile to the end bearing pile. At the same time, the position of the neutral point keeps declining with the consolidation of the soil, and the degree of consolidation reaches 90% constant.