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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。
Aiming at the problem that the design and calculation method of the existing “Technical Code for Construction Pile Foundation” (JGJ 94-2008) can not be applied to the pile foundation of integral abutment bridge, the experimental model of prestressed concrete pile (PHC) Background, PHC pipe pile low cycle reciprocating load pseudo-static test. Through the application of horizontal displacement load, buried strain gauges, earth pressure gauges and specially designed pile body horizontal displacement test method, the failure characteristics of the PHC pipe pile body, the horizontal displacement and strain of the pile body along the pile depth direction, Skeleton curve and hysteretic performance curve, the interaction mechanism of pile-soil is discussed preliminarily, and the equivalent stiffness calculation method of pile-soil interaction of PHC pipe is given. The results show that the prestress and reinforcement ratio have a great influence on the failure modes of PHC pipe piles, and the distribution law of cracks is different. The maximum bending moment develops along the pile depth direction, and the internal forces are redistributed. The smaller the ratio of reinforcement and prestress , The worse deformability (ductility), the more serious the damage, and the poor effect of pile-soil interaction. The PHC model pile basically behaves as linear elasticity at the initial stage of loading, and the horizontal load is mainly borne by the model pile. When the model pile is cracked The concrete in the pullout zone was withdrawn from work and its load increased slowly, showing obvious nonlinearity. After that, the increase of the horizontal load was mainly caused by the soil resistance around the pile. When the soil pressure reached the limit, the load began to descend and rapidly destroyed. The process model piles show good plasticity and deformation capacity, large ductility coefficient, good seismic performance, applicable to the monolithic bridge abutment pile foundation, the results of the study can be used for reference design and calculation of the relevant specifications.