桥台竖向裂缝发展的影响因素分析研究

Analysis on Influence Factors of the Development of Vertical Cracks for Abutment

为分析桥台在施工过程中受混凝土收缩、温度变化等作用下的开裂原因,并讨论台身横向防裂钢筋、桩基刚度、承台与台身混凝土龄期差、台身后浇带的设置等因素对桥台受力性能的影响,利用Midas/FEA对桥台进行非线性计算,探究出了台身的开裂机理,并得到各因素的影响,最后给出防治建议。主要结论为:台身裂缝的原因为混凝土收缩和温度变化作用下,承台与台身的变形受桩基约束,台身在桩基上方产生裂缝并竖向向上发展;配筋率相同时,台身横向防裂钢筋宜采用"细而密"的布置方式;满足承载力要求时,适当减小桩径可减小裂缝宽度;台身后浇带的设置很大程度上减小了裂缝宽度;可不考虑承台与台身混凝土龄期差对裂缝的影响。

To analyze the cracking cause of abutment,subject to concrete shrinkage and temperature variation in construction process,and discuss some factors impacting on mechanical property of abutment,such as lateral anti-cracking steel bar,rigidity of pile foundations,age gap of concrete between cushion cap and abutment body,and post-cast strip of abutment body,the nonlinear calculation of abutment was executed by Midas/FEA software.Then the cracking mechanism of abutment was obtained,and the influence of that factors was analyzed,lastly,the prevention and control proposal was given for abutment cracking.Results show that the causing of abutment cracks is,with concrete shrinkage and temperature change,the deformation between cushion cap and abutment body is constrained by pile foundations,and the cracks forming over pile foundations develop upward.Based on equal ratio of reinforcement,the arrangement of lateral anti-cracking steel of small and dense is more beneficial.When the bearing capacity meets standard,the width of crack decreases with the decrease of diameter of pile foundation.Post-cast strip of abutment body contributes to the decrease of width of crack well.The impact on crack width is discounted of age gap of concrete between cushion cap and abutment body.