PHC管桩-土相互作用受力性能拟静力试验

发布时间：2018-10-19 18:11

【摘要】：针对现有《建筑桩基技术规范》(JGJ 94—2008)中设计计算方法难以适用于整体式桥台桥梁桩基的问题,以预应力高强混凝土(Prestress High Concrete,PHC)管桩试验模型为背景,进行了PHC管桩低周往复荷载拟静力试验。通过在桩顶施加水平位移荷载、埋设应变片、土压力计以及特殊设计的桩身水平变位测试方法,得到了PHC管桩桩身破坏特点、沿桩深方向上桩身水平位移与应变、骨架曲线和滞回性能曲线,初步探讨了桩-土相互作用机理,给出了PHC管桩-土相互作用的等效刚度计算方法。试验结果表明:预应力度和配筋率对PHC管桩的破坏模式有较大影响,裂缝分布规律不同,最大弯矩沿桩深方向发展,内力重分布;配筋率和预应力度越小,变形能力(延性)越差、破坏越严重,桩-土相互作用效果不佳;PHC模型桩在加载初期基本表现为线弹性性能,且水平外荷载主要由模型桩承担;当模型桩开裂后拉区混凝土退出工作,荷载增加减缓,表现出较明显的非线性性能,此后水平外荷载的增加主要由桩周土抗力承担;当桩周土压力达到极限时荷载开始下降并迅速破坏;试验全过程各模型桩均表现出了良好的塑性性能和变形能力,延性系数较大,抗震性能较好,可适用于整体式桥台桥梁桩基,研究结果可供有关规范的设计计算参考。
[Abstract]:In view of the problem that the design and calculation method in JGJ 94-2008 is difficult to be applied to the pile foundation of monolithic bridge abutment, the experimental model of prestressed high-strength concrete (Prestress High Concrete,PHC) pipe pile is taken as the background. Quasi static test of PHC pipe pile under low cycle reciprocating load was carried out. By applying horizontal displacement load on top of pile, embedding strain gauge, soil pressure gauge and testing method of horizontal displacement of pile body of special design, the failure characteristics of pile body in PHC pipe are obtained, and the horizontal displacement and strain of pile body along the direction of pile depth are obtained. Skeleton curve and hysteretic behavior curve, the mechanism of pile-soil interaction is discussed, and the equivalent stiffness calculation method of PHC pipe pile-soil interaction is given. The test results show that the degree of prestress and the ratio of reinforcement have great influence on the failure mode of PHC pipe pile, the distribution of crack is different, the maximum bending moment develops along the direction of pile depth, the distribution of internal force is redistributed, the ratio of reinforcement and degree of prestress is smaller, The worse the deformation capacity (ductility) is, the more serious the damage is, the worse the pile-soil interaction effect is, the more linear elastic behavior of the PHC model pile is at the initial loading stage, and the horizontal external load is mainly borne by the model pile. When the concrete in the tensile zone of the model pile exits from work, the increase of load slows down and shows obvious nonlinear performance. After that, the increase of the horizontal external load is mainly borne by the resistance of the soil around the pile. When the soil pressure around the pile reaches the limit, the load begins to decrease and destroy rapidly, and all the model piles show good plastic performance and deformation ability, the ductility coefficient is larger, and the seismic performance is better during the whole test process. It can be applied to the pile foundation of monolithic abutment bridge, and the research results can be used as reference for the design and calculation of relevant codes.
【作者单位】：福州大学土木工程学院;
【基金】：国家自然科学基金项目(51578161,51278126)
【分类号】：TU473.1

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