孟加拉国沉积层地质不同护壁泥浆对桩基承载力的影响研究  

Effects of Different Slurry Walls in Sedimentary Deposits on Load Bearing Capacity of Pile Foundation in Bangladesh

作　　者：吴问兵 WU Wen-bing(The Fourth Engineering Co.,Ltd.,China Railway Major Bridge Engineering Group,Nanjing 210031,China)

机构地区：[1]中铁大桥局集团第四工程有限公司,江苏南京210031

出　　处：《世界桥梁》2023年第2期8-13,共6页World Bridges

摘　　要：孟加拉国帕德玛大桥铁路连接线桥梁包括混凝土箱梁高架桥和简支钢桁梁桥2种形式,桩基类型均为钻孔灌注桩。项目沿线地质均为第四系沉积层。为给工程桩设计提供参考,分别采用传统膨润土泥浆、改良PHP膨润土泥浆和化学泥浆施工试验桩,选择代表性试验桩分析地勘数据和静载试验的桩侧阻力,并提出相应的桩基承载力参考标准。结果表明:试验桩的地勘桩侧阻力相近,但静载试验桩侧阻力差异较大;采用传统膨润土泥浆施工,单位面积极限桩侧阻力仅能达到地勘值的51.3%,采用改良PHP膨润土泥浆和化学泥浆能够大幅提高单位面积极限桩侧阻力,分别可达到地勘值的1.04倍和1.485倍;采用传统膨润土泥浆、改良PHP膨润土泥浆和化学泥浆施工,单位面积极限桩侧阻力分别为31.0,60.9,91.7 kPa,可作为类似桩基设计和施工的参考标准。基于试验结果,全线混凝土箱梁高架桥的工程桩设计均采用改良PHP膨润土泥浆施工,简支钢桁梁桥的工程桩设计均采用化学泥浆施工,且验证性荷载试验结果显示全部抽检工程桩的承载力均满足设计要求。The Padma Bridge Rail Link Project in Bangladesh incorporates two types of viaducts, specifically the concrete box viaducts and simply-supported steel truss girder viaducts that are supported by bored pile foundations. To accommodate the quaternary sediments and assist the design permant piles, trial piles were prepared to examine the effects of three different types of slurry on the foundation construction, including the ordinary bentonite slurry, modified PHP bentonite slurry, and chemical slurry. The geologically-surveyed and the tested shaft resistances(by static load test) of the trial piles were analyzed and the corresponding references for the load bearing capacity of the permanent piles were presented. It is shown that the surveyed shaft resistances of the trial piles are approximate, but vary greatly in the static load tests. When using ordinary bentonite slurry, the ultimate shaft resistances per unit area of the trial piles can only reach 51.3% of the surveyed data, and when the PHP bentonite slurry and chemical slurry are used, the shaft resistances of the trial piles are able to be 1.04 and 1.485 times of the surveyed data, respectively. The utilization of the ordinary bentonite slurry, modified PHP bentonite slurry and chemical slurry results in different ultimate shaft resistance per unit area, of 31.0,60.9 and 91.7 kPa, respectively, which can be taken as references in the design and construction of similar pile foundation. As per the geologically-surveyed and tested data, all the permanent piles of the concrete box girder viaducts were determined to construct using modified PHP bentonite slurry, and all the permanent piles of the simply-supported steel truss girder viaducts using chemical slurry. The checking load test proved that the load bearing capacity of the permanent piles meet the design requirements.

关 键 词：铁路高架桥 钻孔灌注桩 沉积层 泥浆护壁 桩基承载力 桩侧阻力 地勘 静载试验 

分 类 号：U443.154[建筑科学—桥梁与隧道工程]