摘要
为研究桩底位置对含可液化土层桩承桥台地震反应的影响,依托唐山大地震震害实例,建立双桩情况下可液化土层位于地基中部桩承桥台的三维数值模型,并基于有限差分法进行动力计算,从静力平衡时模型底部水压力、动力计算中桥台倾斜方向和沉降量与实际震害调查结果对比3个方面验证模型的合理性。以该模型为基准,通过改变桩长,分析不同桩底位置情况下桩承桥台地震位移响应、桩身弯矩响应以及可液化土层的液化特征。研究结果表明:所有桩长情况下,桥台震害位移模式均为整体滑移前倾式,桥台向河心倾斜。桥台位移与倾斜角度随桩长的增加逐渐减小,与桩底相对可液化土层位置无明显关系,同时桥台与路堤、桥台与地基之间的相对位移也逐渐减小。桩端位于可液化土层下界面上方时,桩身弯矩最大值出现在桩顶处,桩长的变化对于减弱土层液化影响较小,可液化土层接近完全液化。桩端位于可液化土层下界面下方时,桩身弯矩最大值出现在桩顶以及可液化土层与非液化层交界面处,且最大值远大于位于上方的情况,桩长越长,可液化土层中实际发生液化的土体越少,桥台整体稳定性越好,但需对可液化土层与非液化层交界面和桩顶位置进行抗震加固设计。若可液化土层发生液化,其初次液化发生的时刻均为该土层加速度峰值时刻。研究结果可为类似工程项目提供参考。
To analyze the influence of different pile bottom positions on seismic response of piled abutment with liquefiable soil layer,a three-dimensional numerical model of double-pile supported abutment with liquefiable soil layer was established,based on the damage case of the great Tangshan earthquake,and the dynamic calculation was carried out with the finite difference method.The rationality of the model was verified from three aspects:the hydrostatic pressure at the model bottom in static equilibrium,the abutment dip direction and settlement in dynamic calculation,and the comparison with the actual seismic damage investigation results.The seismic displacement response,pile bending moment response and soil liquefaction characteristics of piled abutment with different pile lengths were analyzed.The results showed that under all pile lengths,the seismic displacement mode of piled abutment was the overall sliding forward type,and the abutment was inclined to the river center.The displacement and inclination angle of the abutment became smaller with the increase of the pile length,which had no obvious relationship with the relative position of pile bottom and liquefiable soil layer,while the relative displacement between abutment,embankment and foundation decreased.The maximum bending moment occurred at the pile top when the pile end was above the lower interface of liquefiable soil layer,and the change of pile length had little effect on weakening soil liquefaction.Meanwhile,the liquefiable soil layer was close to complete liquefaction.When the pile end was below that interface,the maximum bending moment occurred at the pile top and the interface between liquefiable and non-liquefiable soil layer,and the maximum value was much greater than that above.The longer the pile length,the less the soil actually liquefied in the liquefiable soil layer,and the better the overall stability of the abutment.However,the interface between the liquefiable and the non-liquefiable layer and the pile top should be reinforced.The initial
作者
魏红卫
肖长红
吴忠诚
WEI Hongwei;XIAO Changhong;WU Zhongcheng(School of Civil Engineering,Central South University,Changsha 410075,China)
出处
《铁道科学与工程学报》
EI
CAS
CSCD
北大核心
2022年第6期1647-1657,共11页
Journal of Railway Science and Engineering
基金
国家自然科学基金面上项目(51778639,51678573)。
关键词
桩长
可液化土层
桩承桥台
地震响应
数值模拟
pile length
liquefiable soil layer
piled abutment
seismic response
numerical simulation
