近、远场强震下深水桥梁群桩基础的非线性响应及损伤特性

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振动与冲击 ›› 2017, Vol. 36 ›› Issue (24) : 13-22.

论文

江辉1，王志2，白晓宇1,曾聪1

作者信息 +

Nonlinear responses and damage characteristics for group-piles foundation of a deep-water Bridge under strong near-field and far-field earthquakes

JIANG Hui1, WANG Zhi2, BAI Xiao-yu1, ZENG Cong1

Author information +

文章历史 +

摘要

以某大型深水桥梁的群桩基础为对象，建立考虑动水效应和桩-土相互作用的非线性计算模型，以近、远场强震记录为输入，分析了不同水深下群桩基础的动力响应及损伤特性。可发现，近场地震下群桩基础的动力响应均大于远场，弯矩、剪力、位移的最大增幅分别出现在冲刷线以下不同深度处，轴力的最大增幅则出现在桩顶处，弯矩、剪力、位移和轴力的最大增幅分别为150.6%、227.2%、333.4%和64.2%。近场地震下，墩底、桩顶是主要易损部位，当PGA=0.38g和0.6g,时桩顶损伤指数分别为0.19和0.40，损伤水平及范围随地震动强度增加而增大，随水深增加而略有增大；远场地震下，群桩基础主要处于弹性状态。由于桩周土的约束作用，一定深度的土层交界处也可能出现桩基损伤，且损伤程度会随地震动强度的增加而增大，并向两端扩散。对比表明，近场地震下深水群桩基础的动力响应及损伤均明显大于远场，表明脉冲型近断层地震动具有更高的变形和耗能需求，应在深水桥梁的抗震设计尤其是基础延性设计中予以重视。

Abstract

Taking the group-piles foundation of a large deep-water bridge as a study object, its nonlinear calculation model considering hydrodynamic effect and pile-soil interaction was built. The strong near-field and far-field earthquake records were taken as inputs, the dynamic response and damage characteristics of the foundation under different water depths were analyzed. The results showed that the dynamic responses of the foundation under near-field earthquakes are larger than those under far-field earthquakes; the maximum increments of shear force, moment, and displacement appear at different depths beneath the erosion line, while those of axial force appear at the pile top, the maximum increments of moment, shear force, displacement and axial force are 150.6%, 227.2%, 333.4% and 64.2%, respectively; under near-field earthquakes, the pier bottom and pile top are main vulnerable positions, the damage indexes of the pile top are 0.19 and 0.40, respectively under peak ground accelerations (PGAs) of 0.38g and 0.6g; the damage level and range increase with increase in earthquake intensity, and increase slightly with increase in water depth; under far-field earthquakes, the group-piles foundation is mainly in elastic state, due to the constraint effect of soil around piles, structural damage may occur at some junctions of soil layers with a certain depth, the damage level increases with increase in earthquake intensity and spreads to both ends. Comparisons showed that the dynamic responses and structural damage of the foundation under near-field earthquakes are significantly greater than those under far-field earthquakes; the impulse type near-field earthquakes have higher deformation and energy-dissipation demands, more attentions should be paid to the aseismic design of deep-water bridges, especially, the ductility design of their foundations.

导出引用

江辉1，王志2，白晓宇1,曾聪1. 近、远场强震下深水桥梁群桩基础的非线性响应及损伤特性[J]. 振动与冲击, 2017, 36(24): 13-22

JIANG Hui1, WANG Zhi2, BAI Xiao-yu1, ZENG Cong1. Nonlinear responses and damage characteristics for group-piles foundation of a deep-water Bridge under strong near-field and far-field earthquakes[J]. Journal of Vibration and Shock, 2017, 36(24): 13-22

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