摘要
为研究桩侧-桩端联合压浆技术对黄土地区桥梁灌注桩桩基承载特性的影响,基于传统压浆装置,开发出新型桩侧-桩端联合压浆装置,通过对3根不同压浆方式的模型桩开展室内模型试验,分析不同压浆方式下各模型桩承载力、轴力、侧摩阻力变化曲线,评价新型联合压浆装置的压浆效果,并在静载试验后开挖模型箱,获得浆脉的分布情况,分析浆液在黄土中的扩散规律,探究联合压浆技术对黄土地区桩基承载特性的提升机理。结果表明:桩侧-桩端联合压浆技术对黄土地区桩基承载力的提升效果优于桩端压浆技术,相比于常规模型桩S_(1),桩端压浆桩S_(2)的极限承载力提高29%,桩侧-桩端联合压浆桩S_(3)在相同注浆量情况下极限承载力提高71%;极限荷载下,S_(1)、S_(2)、S_(3)桩端阻比分别为19.2%、43.33%、34.9%,侧阻比分别为80.80%、56.67%、65.1%;桩侧-桩端联合压浆技术改变了黄土地区桩基侧摩阻力曲线"两头小中间大"的特征,表现出两头大中间小的R形,整体数值得到提升,且异步发挥的特点得到改善;无论何种压浆方式,浆液在黄土中的扩散方式均以压密和劈裂注浆为主,桩端压浆桩和联合压浆桩的桩底均形成圆柱状浆土固化物和3条形状明显的浆脉,同时联合压浆桩浆液上返高度达60 cm,使下部桩身的平均直径增大1~1.5 cm,联合压浆喷头的压浆效果显著,可为黄土地区桩基联合压浆的设计与施工提供参考。
In order to study the influence of lateral and end combined grouting technology on the bearing characteristics of bridge cast-in-place piles foundation in Loess Area.A new type of lateral and end combined grouting device was developed based on the traditional grouting device.Indoor model tests were carried out on model piles with different grouting methods,the bearing capacity,axial force and side friction curves of each model pile were analyzed to evaluate the grouting effect of the new combined grouting device.After the static load test,the model box was excavated to obtain the distribution of grout veins,analyze the law of grout diffusion in the loess,and explore the mechanism of improving bearing characteristics of pile foundation in Loess Area.The results show that the lateral and end combined grouting technology is better than the pile end grouting technology,in improving the bearing capacity of the pile foundation in the Loess Area.Compared with the conventional model pile S_(1),the ultimate bearing capacity of pile end grouting pile S_(2) is increased by 29%,and the ultimate bearing capacity of lateral and end combined grouting pile S;is increased by 71%,which has the same grouting quantity whit S_(2).Under the action of ultimate load,the end resistance ratios of S_(1),S_(2) and S_(3) pile are 19.2%,43.33%and 34.9%,and the side resistance ratios are 80.80%,56.67%and 65.1%respectively.The lateral and end combined grouting technology has changed the characteristics of small at both ends and large in the middle of the side friction curve of pile foundation in Loess Area,showing an R-shape with large at both ends and small in the middle.The overall value has been improved,and the characteristics of asynchronous play have been improved to some extent.No matter what kind of grouting method,the main diffusion methods of slurry in loess are compaction grouting and splitting grouting.The bottoms of pile-end grouting pile and combined grouting pile have formed cylindrical mortar solidified material and 3 obvious slurry veins.At the same time,the slurry return-height of combined grouting pile reaches 60 cm,which makes the average diameter of the lower pile body increase by 1 to 1.5 cm.The grouting effect of combined grouting nozzle is remarkable,which can provide reference for the design and construction of combined grouting of pile foundation in Loess Area.3 tabs,13 figs,28 refs.
作者
薛振年
冯泓鸣
任晨宁
周志军
XUE Zhen-nian;FENG Hong-ming;REN Chen-ning;ZHOU Zhi-jun(Shaanxi Communications Holding Group Co.,Ltd.,Xi'an 710075,Shaanxi,China;School of Highway,Chang'an University,Xi'an 710064,Shaanxi,China;China Railway First Survey and Design Institute Group Co.,Ltd.,Xi'an 710043,Shaanxi,China)
出处
《长安大学学报（自然科学版）》
CAS
CSCD
北大核心
2021年第6期19-28,共10页
Journal of Chang’an University(Natural Science Edition)
基金
国家自然科学基金项目(51878064)。
关键词
道路工程
桩侧-桩端联合压浆
模型试验
桥梁灌注桩
侧摩阻力
road engineering
lateral and end combined grouting
model test
bridge cast-in-place pile
pile side resistance
