复杂结构–桩–土体系下的桩–土动力p–y曲线

以天津站交通枢纽工程为背景，开展了复杂结构–桩–土相互作用振动台模型试验，研究了桩土相互作用的动力特性。运用弹性地基梁理论，得出弯矩时程和土压力，采用实测桩的加速度值积分求得桩的位移，得到桩–土动力 p – y 曲线，求出了不同深度及不同时间段阻尼与弹簧刚度系数分布规律。研究表明：受底部筏板的影响，阻尼与土弹簧刚度沿桩身分布可近似考虑成分段线性，分段点约在桩身上部 1/3 范围处。阻尼与弹簧刚度均随埋深的增加而增大；随着地震动的持续，阻尼基本稳定，只在桩底略有增大；弹簧刚度随振动时间持续有所降低，且随埋深增大，其降低的幅度越大。

Dynamic p-y curves of pile-soil under complex structure-pile-soil system

Shaking table tests on complex structure-pile-soil interaction are accomplished for the transport junction of Tianjin Station,and dynamic properties of pile-soil interaction are studied.The time history of moment and soil pressure are obtained from the theory of elastic foundation and the displacement of pile is acquired through integral of pile acceleration measured from the tests,and then dynamic p-y curves of pile-soil are obtained.The distribution rules of damping and spring stiffness coefficient at different depths during different periods are calculated.It is shown that the distribution of damping and spring stiffness coefficient along the pile can approximately be taken as piecewise linearization,and the turning point is at about 1/3 length of the pile from the top.Both the damping and the spring stiffness coefficient increase with the increase of pile depth;and with the continuous vibration,damping is stable along the pile except slight increase at the bottom of the pile while the spring stiffness coefficient decreases continuously,and the decrease magnitude is expanded as the depth increases.