带EPS的整体式桥台-桩-土相互作用拟静力试验

整体桥中台后土压力在温度循环作用下会发生较大变化，这种季节性横向土压力的变化在每次温度循环后会持续增大，其实际所受水平土压力会远大于桥台设计时的压力，同时桥台桩基会产生累积和残余变形，因而有效减少台后土压力与桥台桩基的累积和残余变形至关重要。为此以桥台-H形钢桩试件为研究对象，通过在桥台侧向施加水平位移荷载，开展带膨胀聚苯乙烯（EPS）填料板的整体式桥台-桩-土往复荷载拟静力试验，分析桥台、桩基的骨架曲线、滞回曲线及其沿入土深度方向的水平变形和桥台转角等的变化规律，初步研究EPS填料板的厚度对桥台-桩基-土相互作用受力性能的影响。试验结果表明：在台后埋设EPS填料板能有效减小上部结构变形时桥台所受到的水平力，最大可减小31%；同时，也可减小模型试件的累积变形，其随着EPS厚度的增加而逐渐减小，尤其对桩的累积变形减小最为显著，最大减小了74.3%；在台后埋设EPS填料板也可有效减小台后填土对桥台转角的约束作用；台后埋设EPS填料板会使单步位移荷载作用下产生的变形有所增大，但幅度不大；试验全过程各模型试件均表现出了良好的弹性性能和变形能力。

Experiment on Abutment-pile-soil Interaction with Expanded Polystyrenes in Integral Abutment Jointless Bridges

The earth pressure of backfill behind the abutment of integral abutment jointless bridge (IAJB) varies substantially as the bridge girder is easily subjected to load due to cycling temperature. This earth pressure that increases continuously due to seasonal variations in temperature, results in the actual earth pressure of the backfill is much larger than the designed earth pressure, and the accumulative deformations in abutment and pile emerge. Therefore, the crucial problems with IAJBs include effectively reducing the earth pressure behind the abutment, eliminating the accumulative deformation, and reducing the horizontal thrust of the girder under temperature load. Based on the specimens of abutment H-shaped steel pile, a low-cyclic, pseudo-static experiment was carried out on abutment pile soil interactions in IAJBs that incorporate expanded polystyrenes (EPS). The hysteresis curves and their skeletons of the abutment and pile, the horizontal deformations along the depth direction of the soil, and the angles of the abutments were achieved. The influence on abutment-pile-soil interaction behavior was preliminarily studied by different thickness of EPS fillers. The results of these investigations indicate that the horizontal thrust on the abutment due to girder expansion is reduced effectively after the burial of the EPS fillers behind the abutment. Specifically, the thrust reduces 31% when the thickness of the EPS filling is 15 cm. The accumulative deformation of the pile and abutment decreases as the thickness of the EPS filling increases, especially at the depth of 0.4 m below the top of the pile, where the deformation reduces 74.3%. In addition, the EPS filling behind the abutment remarkably reduces the constraints on the rotation angle by the backfill. Nevertheless, the deformations under a single step of displacement loading increase by a small amount after the burial of the EPS fillers. These fillers provide adequate elasticity and flexibility, and they exhibit reasonable mechanical properties under cycling temperature loads.