摘要
为探明公路桥梁桩基穿越溶洞的荷载传递机制,开展了回填法处理溶洞时桩基荷载传递机制现场试验,结合数值仿真方法,研究了回填法处治溶洞时穿越不同高度溶洞的桩基竖向承载特性和荷载传递机制,提出了不同洞高下回填材料引起的桩侧负摩阻力最大值及其分布范围占比的变化规律。结果表明:岩溶区桩侧负摩阻力的产生受溶洞类型的影响,填充型溶洞桩侧土体沉降较小,可为桩基提供较小的正摩阻力;非填充型溶洞桩侧土体沉降较大,桩侧表面会产生负摩阻力;采用回填法处理溶洞后,穿越溶洞桥梁桩基的竖向极限承载力随洞高增加而逐渐减小;洞高由3 m增加至12 m时,桩基竖向极限承载力对应的桩侧负摩阻力分布范围占洞高的比例由0%增加至27.14%。建议在实际设计中采用回填法处理溶洞时,应考虑穿过溶洞桥梁桩基在溶洞范围产生的桩侧负摩阻力对桩基竖向承载特性的影响;洞高为3~12m时,建议在溶洞顶面以下0、0.106H、0.214H、0.271H(H为洞高)范围内按负摩阻力计算桩基承载能力,以确保溶洞处治后回填材料固结沉降期间桥梁桩基承载安全。
In order to understand the load transfer mechanism of highway bridge pile foundation passing through karst cave,the field test of bridge pile foundation treated by backfilling method is carried out.Combined with the numerical simulation method,the vertical bearing characteristics and load transfer mechanism of pile foundation passing through karst caves with different heights are studied,and the variation law of the maximum value of the negative skin friction caused by backfilling material in different cave heights and its proportion of distribution range are discussed.The results show that the negative skin friction in the karst area is affected by the type of karst cave,i.e.when the settlement of the soil on the side of the pile of the filled karst cave is smaller,the pile side can provide less positive friction for the pile foundation;when the settlement of the soil of the pile side of the unfilled karst cave is larger,the pile side can produce negative friction.After the karst cave is treated by the backfilling method,the vertical ultimate bearing capacity of the bridge pile foundation passing through the karst cave decreases with the increase of the cave height,e.g.when the cave height increases from 3 m to 12 m,the distribution range of the negative skin friction corresponding to the vertical ultimate bearing capacity of pile foundation increases from 0% to 27.14%.It is suggested that in the actual design,when the backfilling method is used to deal with the karst cave,the influence of the negative skin friction caused by the pile foundation passing through the karst cave on the vertical bearing characteristics of the pile foundation should be considered.When the height of karst cave is 3–12 m,the bearing capacity of the pile foundation should be calculated according to negative skin friction in the ranges of 0,0.106H,0.214H and 0.271H(H is the cave height) below the top surface of karst cave,so as to ensure the bearing safety of bridge pile foundation during the consolidation and settlement of backfill materials after cave treatment.
作者
陈慧芸
冯忠居
白少奋
董建松
夏承明
蔡杰
CHEN Hui-yun;FENG Zhong-ju;BAI Shao-fen;DONG Jian-song;XIA Cheng-ming;CAI Jie(School of Architecture and Civil Engineering,Xihua University,Chengdu,Sichuan 610039,China;School of Highway,Chang’an University,Xi’an,Shaanxi 710064,China;Fujian Transportation Construction Quality and Safety Center,Fuzhou,Fujian 350001,China;Sanming Puyan Highway Co.,Ltd.,Sanming,Fujian 353000,China)
出处
《岩土力学》
EI
CAS
CSCD
北大核心
2023年第5期1405-1415,共11页
Rock and Soil Mechanics
基金
国家重点研发计划(No.2018YFC1504801-04)
福建省交通运输科技项目(No.2018Y032)。
关键词
桥梁工程
溶洞
桩基础荷载传递机制
现场试验
负摩阻力
bridge engineering
karst cave
load transfer mechanism of pile foundation
field test
negative friction
