堆载作用下桥梁被动桩偏移受力分析及处理措施

Force Analysis and Handling Measures for Offsetting of Bridge Passive Piles Under Action of Stacked Load

为研究堆载对桥梁被动桩的影响,以某桥为背景,采用有限差分法进行被动桩偏移受力分析,判断基桩能否继续使用并提出处理措施。采用有限差分法建立下部结构模型,计算堆载作用下桥墩偏移并与实测值对比,分析基桩内力及偏移,按圆形截面钢筋混凝土偏心受压构件计算最大裂缝宽度并评估基桩状态,根据评估结果提出处理措施。结果表明:堆载导致桥墩偏移,墩顶横向偏移计算值与实测值比较吻合;堆载作用下,基桩产生了较大偏移和弯矩,桩顶轴力和桩身轴力分布不均,并产生不同程度的负摩阻力(距堆载越近负摩阻力越大);最大裂缝宽度为0.08mm,小于规范限值,判断基桩可以继续使用,提出堆载反压和应力释放孔联合纠偏,开挖卸载、水平顶推结合应力释放孔纠偏等处理措施。

To study the influences of stacked load on the bridge passive piles,a bridge was taken as the research object,the force analysis of offsetting of the passive piles was conducted by the finite difference method,the piles were judged if they could be continuously used and the corresponding handling measures were proposed.The models for the substructure of the bridge were set up also by the finite difference method,the offsetting of the piers of the bridge under the action of the stacked load was calculated and the calculated values were compared to the measured ones.The internal forces and offsetting of the piles were analyzed.In terms of the circular reinforced concrete eccentric compression components,the maximum crack width of the piles was calculated,the force conditions of the piles were assessed and based on the assessment,the handling measures were proposed.The results show that the stacked load causes the offsetting of the piers and the calculated and measured values of the lateral offsetting of the pier tops are accordant.Under the action of the stacked load,the great offsetting and bending moment occur in the piles,the axial force distribution in the pile tops and pile shafts is not uniform and the negative frictional resistance of different degrees occurs （the closer to the stacked load,the greater the negative frictional resistance will be）.The maximum crack width of the piles is 0.08 mm and is less than the specified values in the codes.It is therefore judged that the piles can be continuously used and the handling measures of rectifying the offsetting of the piles,using the combined method of reverse compression of the stacked load and stress release holes and the measures of excavating,unloading,horizontal pushing aided by the utilization of the stress release holes are also proposed.