摘要
对传统注浆喷头进行优化设计,验证新型注浆喷头的工程适用性。通过室内模型试验,对不同注浆喷头的模型桩基进行静载试验以及开挖观测,从承载特性和浆液扩散2个方面综合对比分析新型注浆喷头的注浆加固效果。在相同注浆参数下,采用新型注浆喷头的模型桩(S2桩)较传统注浆喷头下的模型桩(S1桩)承载力提高了20%,S1桩侧摩阻力呈现先增大后减小的趋势,S2桩从桩深55cm截面处向下持续增大,侧摩阻力的发挥特性被显著改善。极限荷载下S1桩的端阻力占比为38.33%,而S2桩的端阻比仅为27.78%,采用2种注浆喷头的模型桩均表现出了端承摩擦桩的特性。开挖模型箱发现,S1桩在注浆后浆液主要在桩底大范围扩散,桩端以上小范围内有浆脉向上劈裂的痕迹,S2桩浆液不仅在桩端向桩身四周劈裂,而且在无泥浆护壁情况下从桩端沿着桩侧上返了50 cm,显著改善了桩身下半部的桩-土界面。通过分析模型桩静载试验结果以及对模型桩进行开挖观测浆液在桩端的扩散情况,验证了新型注浆喷头的可行性及有效性,表明其值得进一步研究与推广。
The design of the traditional grouting nozzle was optimized and the engineering applicability of the new grouting nozzle was verified.Through the laboratory model test,static load test and excavation observation of model pile foundation with different grouting nozzles were carried out.The grouting reinforcement effect of the new grouting nozzle was comprehensively compared and analyzed in terms of both bearing characteristics and slurry diffusion.The results show that under the same grouting parameters,the bearing capacity of the model pile(S2) with the new grouting nozzle increased by 20% as compared to that of the model pile(S1) with the traditional grouting nozzle.The lateral friction resistance of the S1 pile increased first and then decreased,while the lateral friction resistance of the S2 pile is significantly improved with the continuous increases from the section of 55 cm depth downward.The end resistance ratio of the S1 pile under the ultimate load was 38.33%,while that of the S2 pile was only 27.78%.The model piles with two different types of grouting nozzles both exhibited the characteristics of end-bearing friction piles.After excavation of the model box,it was found that the slurry of the S1 pile mainly diffuses at the pile end after grouting,and the upward splitting of the slurry above the pile end is limited.The slurry of the S2 pile not only splits around the pile end but also returns 50 cm up along the pile side from the pile end without slurry wall protection.It significantly improved the pile-soil interface in the lower part of the pile body.The feasibility and validity of the new grouting nozzle were verified by analyzing the static load test results and observing the grout diffusion at the end of the pile,which indicated that it is worthy of further research and promotion.
作者
熊彩凤
徐甫
冯泓鸣
周志军
XIONG Caifeng;XU Fu;FENG Hongming;ZHOU Zhijun(Yunnan Transportation Development Highway Engineering Co.,Ltd.,Kunming 650200,China;School of Highways,Chang’an University,Xi’an 710064,China;Xi’an Highway Engineering Testing Center,Xi’an 710064,China)
出处
《铁道科学与工程学报》
EI
CAS
CSCD
北大核心
2022年第6期1585-1593,共9页
Journal of Railway Science and Engineering
基金
国家自然科学基金资助项目(51878064)。
关键词
灌注桩
桩端后注浆
模型试验
侧摩阻力
浆液扩散
cast in place pile
post-grouting
model test
side friction
slurry diffusion
