多雨冲沟区桥梁桩基横向承载特性模型试验研究  

Experimental Study on Model of Lateral Bearing Behavior of Bridge Pile Foundation in Rainy Gully Area

作　　者：陈思晓[1,2] 冯忠居 CHEN Si-xiao;FENG Zhong-ju(School of Highway,Chang'an University,Xi'an Shaanxi 710064,China;Fujian Provinci,al Traffic Construction Quality and Safety Supervision Bureau,Fuzhou Fujian 350001,China)

机构地区：[1]长安大学公路学院,陕西西安710064 [2]福建省交通建设质量安全监督局,福建福州350001

出　　处：《公路交通科技》2018年第12期80-89,共10页Journal of Highway and Transportation Research and Development

基　　金：福建省交通科技项目(201310)

摘　　要：多雨冲沟区桩基础所处环境特殊,冲刷、冲击等横向荷载因素影响桩基础承载力的发挥。为探明该区域桩基础横向承载特性,通过采用自主研发的多雨冲沟区桥梁桩基础室内小比例模型试验平台,最大程度地表征原型的桩土材料、桩土边界条件等技术状态,尽量还原桩基础在实际环境中的受力过程,科学模拟多雨冲沟区桥梁桩基在横向荷载下的受力变化情况。分析桩基础在不同的桩长、冲沟坡度以及桩边距条件下,横向承载力、桩身最大弯矩及其截面位置的变化规律,提出不同斜坡度数下桩基有效桩长的折减系数,给出相关工程技术建议。研究结果表明:随着桩长的增加,桩基的横向承载力逐渐增大,但桩长越长,承载力变化幅度越缓;桩长相同的情况下,坡度越大,桩基础的横向承载力越小。建立了桩基有效桩长计算公式,实践时需考虑不同坡度对应的折减系数;坡度增大,相同条件下的桩基有效桩长逐渐变小。桩身最大弯矩及其截面位置随坡度及桩长的增加而增大,增幅随坡度增大而降低。工程实际上建议:复杂环境下的桩基础处于坡度较大位置时,需适当增加桩顶前缘至岩层坡面间的安全距离,必要时进行边坡专项防护,并对已破损及破碎的岩体采取加固措施。桩基截面配筋计算时,需适当提高距桩顶(20%～30%)桩长范围内的桩基配筋率,坡度大、桩周岩体缺失多等情况需进一步进行专项设计及特殊防护,保证桩基施工安全及后期正常使用。The environment of pile foundation in rainy gully area is special.The lateral load factors such as scour and lash affect the bearing capacity of pile foundation.In order to ascertain the lateral bearing behavior of pile foundation in this area,based on independent R &D indoor small scale model test platform 6f b^dge pile foundation in rainy gully area,the technical state of prototype pile-soil material and the boundary condition and so on are represented to the greatest extent,the stress process of pile foundation in actual environment is restored as far as possible,and the stresses in the bridge pile foundation are simulated seientificaUy.The variation rules of lateral bearing capacity,maximum bending moment of pile body and its section position under different pile lengths,gully gradients and pile spacings are analyzed.The reduction coefficient of effective pile length with different slope angles are put forward,and the relevant engineering technical suggestions are given.The result shows that (1)With the increase of pile length,the lateral bearing capacity of pile foundation increases gradually.But the longer the pile length,the slower the change of bearing capacity.Under the same pile length,the larger the slope,the smaller the lateral bearing capacity of pile foundation.(2)The formula for calculating effective pile length of pile foundation is established,and the reduction coefficients corresponding to different slopes should be taken into account in practice.With the increase of slope,the effective pile length of pile foundation decreases gradually under the same condition. (3)The maximum bending moment of pile body and the section position increase with the increase of slope and length.But the growth of the moment decreases with the increase of slope.The suggestions for practical project are as follows:(1)When the pile foundation is in a steeper slope in the complex environment,the safety distance between the front edge of the pile top and the slope surface of the rock stratum should be increased appropria

关 键 词：桥梁工程 横向承载特性 模型试验 桩基础 多雨冲沟区 

分 类 号：U443.15[建筑科学—桥梁与隧道工程]