DOI: 10.15986j.1006-7930.2018.03.010
利用自制模型箱,以延安新区黄土挖填方场地中的桩筏基础为原型,开展了相似比为1:5的模型试验.通过上部加载模拟上部结构荷载,对桩体纵筋、筏板表面的应变数据以及桩间土体的土压力数据进行采集分析.试验结果表明,随着上部荷载的增大,地基的不均匀沉降导致了基础产生向填方区的偏转,桩体发生明显的弯曲变形,不同部位桩体的应力集中位置以及桩-土相互作用状态有明显区别.在模型试验的基础上探讨了挖填结合地基上桩-土-筏共同作用的计算式.基础设计时应避免桩体全段位于填方地基中,基桩底部应深入稳定原始土体,并通过对填方地基的预处理提高桩周土体的摩擦力,同时应考虑各桩轴向应变数值以及峰值位置的差异,有针对性地考虑桩体的承载能力.
In this paper, a self-made model box was used to prototype the pile-raft foundation in the loess excavation and filling site in Yan'an New Area, and a model test with a similar ratio of 1:5 was carried out. The loading of the upper structure was simulated by the artificial loading, and the strain data of the longitudinal reinforcement of the piles, the surface of the raft and the soil pressure data of the soil between the piles were collected. The results show that with the increase of the upper load, the uneven settlement of the foundation leads to the deflection of the foundation to the fill area, the pile body undergoes significant bending deformation. There are obvious differences in stress concentration position and pile-soil interaction status of piles at different locations. Based on the model test, the calculation formulas for pile-soil-turbulence interaction on excavation and filling foundations are discussed. The piles should be avoided completely in the fill foundation and the bottom of the pile should be deepened to stabilize the original soil, and the friction of the soil around the pile should be improved through the pretreatment of the fill foundation. The axial strain of each pile should also be considered. The difference between the numerical value and the peak position, with a specific consideration of the bearing capacity of the pile.
