倾斜基岩在动载作用下群桩桩顶的最大弯矩分布

Maximum Moment Distribution at the Pile Tops in Pile Groups under Dynamic Loads on the Inclined Rock-base

倾斜基岩上的框架是山地、丘陵地区多见的一种结构形式,但以往对其抗震性能研究很少。本文针对一柱一桩,桩间设置地梁的基础形式,引入了多次透射边界以模拟场地的无限性,利用二次开发后的ANSYS对倾斜基岩上的框架在El-Centro波、Taft波作用下群桩桩顶的荷载分布进行了上下部共同作用分析,以定性的判断地震作用下不同位置桩的受力情况。为了探讨桩端不同约束方式对桩顶最大弯矩的影响,每个算例都分别计算了桩端铰接和桩端固接两种情况。对于倾斜基岩,在A类、B类土层情况下,各桩的最大弯矩分布形状仍呈∪形分布,但长桩所受最大弯矩大于短桩所受最大弯矩。在C类土层情况下,各桩最大弯矩呈∽形分布;当基岩斜率为9∶24时,对于桩端固接的情况,长桩的桩顶最大弯矩大于短桩的桩顶弯矩;对于桩端铰接的情况,则长桩的桩顶最大弯矩小于短桩的桩顶最大弯矩,随着基岩斜率减小,长短桩之间的最大桩顶弯矩差异减小。

The frame on the inclined rock-base often appears in mountanious region, but the study of its seismic behavior is sparely done. Based on muli-transmitting boundary and the ANSYS of secondary development, the load distribution at the pile tops in pile groups under dynamic loads on the inclined rock-base is analyzed considering the soil-structure interraction. The effect on the maximum moment at the pile tops with different restraining conditions at the pile ends is proposed .The distribution of maximum moment at the pile tops is ∪ shape under A B kinds of soil, and under C kind of soil the distribution is ～ shape on the inclined rock-base and ∩ shape on the plain base.