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对深厚软土大面积堆载预压下复合地基的工程力学与变形特性开展了现场试验研究,分析了不同位置和深度的超孔隙水压力、沉降变形以及桩土应力等参数随时间和填土高度的变化规律,为该地区同类工程设计和施工提供科学依据。研究结果表明:(1)复合地基内的超孔隙水压力随着荷载的增加而增大,达到峰值后,随时间延长而逐渐消散,超孔隙水压力的变化略滞后于荷载的变化;超孔隙水压力的最大值出现在下卧层上部,此处附加应力也较大;在下卧层中,随深度的增加,超孔隙水压力逐渐减小。(2)复合地基由路堤中心向外,桩应力、桩间土应力及桩土应力比总体呈现减小趋势。在路堤填筑和预压中,复合地基桩间土应力向桩传递,桩间土应力逐渐减少,桩顶应力逐渐增大,并逐渐趋于稳定。
Field experimental study on engineering mechanics and deformation characteristics of composite foundation under deep preloading of deep thick soft soil is carried out. The effects of excess pore water pressure, settlement deformation, pile-soil stress and other parameters with time and depth on different locations and depths are analyzed. High degree of variation, similar projects in the region for the design and construction to provide a scientific basis. The results show that: (1) The excess pore water pressure in the composite foundation increases with the increase of load. After reaching the peak value, the pore water gradually dissipates with the passage of time and the change of excess pore water pressure slightly lags behind the change of load. The maximum water pressure appears in the upper part of the sub-layer where the additional stress is also large. In the sub-layer, the excess pore water pressure gradually decreases as the depth increases. (2) The composite foundation is outward from the center of the embankment, and pile stress, soil stress between piles and pile-soil stress ratio show a decreasing trend overall. During embankment filling and preloading, the soil stress between the piles in the composite foundation is transferred to the pile, the soil stress between the piles is gradually reduced, and the stress at the pile top gradually increases and gradually becomes stable.