桥梁在役桩的竖向动力响应特性及损伤识别研究

发布时间：2018-03-24 00:13

本文选题：桥梁桩基础　切入点：墩-台-桩-土动力有限元模型　出处：《地震工程学报》2014年04期

【摘要】：基于ANSYS LS-DYNA建立桥梁的墩-承台-桩-土有限元显式动力学模型,模拟桥梁的桩基础在承台上表面施加冲击荷载后完整桩和有断裂缺陷桩的竖向速度响应,分六桩-承台和八桩-承台两种桩基础进行数值计算。结果表明:在所要检测的基桩对应的承台上表面施加冲击力,产生的应力波通过承台到达下方的基桩后沿桩身向下传播,类似于低应变反射波法测桩的原理,应力波在到达桩底桩土交界面或者断裂面等阻抗变化较大处会发生应力波反射,在桩头处的竖向速度响应波形曲线中能识别出反射回的应力波,进而判别桩是完整还是存在断裂损伤;数值计算同时记录承台表面的竖向速度响应,发现承台表面的竖向速度响应波形比桩头处的竖向速度响应波形由于应力波在桩承台界面的多次反射而更加复杂,难以准确判断反射波。
[Abstract]:Based on ANSYS LS-DYNA, an explicit finite element dynamic model of pier-cap pile-soil is established to simulate the vertical velocity response of the whole pile and the pile with fracture defect after the pile foundation of the bridge exerts impact load on the top of the cap. The numerical calculation is carried out on six pile cap and eight pile cap pile foundations. The results show that when the impact force is applied on the top surface of the pile corresponding to the pile to be detected, the stress wave is propagated down the pile body through the pile pile below the cap. Similar to the principle of low strain reflection wave method for pile measurement, stress wave reflection occurs when the impedance changes greatly when reaching the pile-soil interface or fracture surface at the bottom of the pile. In the vertical velocity response waveform curve at the pile head, the reflected stress wave can be identified, and then the pile is judged to be intact or damaged by fracture, and the vertical velocity response of the cap surface is recorded by numerical calculation. It is found that the vertical velocity response waveform on the pile cap surface is more complex than the vertical velocity response waveform at the pile head because of the multiple reflection of the stress wave at the pile cap interface, it is difficult to accurately judge the reflected wave.
【作者单位】：北京交通大学土木工程系;
【基金】：国家自然科学基金(90715013)
【分类号】：U441.3;U446

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