摘要
为研究温州地区后注浆施工对超长灌注桩的承载特性、桩侧及桩端阻力发挥的影响,选取了温州某高架桥的2根摩擦桩和2根端承超长灌注桩,在桩身分别安装了荷载箱和钢筋应变计,浇注完成后一定时间之内进行了桩端及桩侧后注浆试验。在注浆前后对试验桩分别进行了静载试验和桩身轴力测试,得到了注浆前后超长灌注桩轴向承载力、桩侧摩阻力和桩端阻力、荷载-位移关系等数据。根据试验桩的试验数据进行了计算和分析。结果表明:桩侧和桩端后注浆,可显著提高超长灌注桩的轴向承载力,在同样的荷载作用下,桩的轴向位移明显降低;桩侧后注浆能显著提高单位桩侧摩阻力,但同一桩的不同土层,以及同土层中的不同桩,提高的幅度均有一定差异;总体上对粗粒土的影响效果好于细粒土,桩侧后注浆宜以改善桩侧粗粒土阻力为主;桩端后注浆对桩端阻力的提高效果,端承桩好于摩擦桩,桩端后注浆影响深度有限,桩端后注浆宜主要用于改善端承桩沉淀层及附近土层特性;后注浆不会改变超长灌注桩的荷载传递规律,桩侧摩阻力仍然需要分层逐渐发挥,但桩身荷载-位移关系曲线会变缓,为同时达到提高基桩承载力和减小桩身沉降的效果,对于超长灌注桩,宜首选进行桩侧后注浆。
In order to study the influence of post-grouting on bearing characteristics,pile shaft friction and end bearing capacity of super-long cast-in-place piles in Wenzhou area,2 friction piles and 2 end bearing super-long cast-in-place piles on a viaduct are chosen,load cell and strain gauge are installed respectively on the reinforcement cage,post-grouting work is carried out at the end of the pile and the side of the pile within a certain time after the concrete pouring.Static load test and axial force test are carried out on the chosen piles before and after the post-grouting,and the date of pile bearing capacity,pile shaft resistance,pile end bearing capacity,and load-displacement relationship of super-long cast-in-place pile are obtained before and after the post-grouting.The calculation and analysis are carried out according to the test data of the test piles.The result shows that(1)the bearing capacity of the super-long cast-in-place pile can be significantly increased by post-grouting at the pile shaft and end,and the axial displacement of the pile can be significantly reduced under the same load;(2)the post-grouting at the pile shaft can significantly improve the unit resistance of pile shaft,but different soil layers of the same pile and different piles in the same soil layer have certain differences in the amplitude of improvement;(3)the effect on coarse-grained soil is better than that on fine-grained soil,the post-grouting can mainly be used to improve the unit resistance of pile shaft on coarse-grained soil;(4)for the influence of post-grouting on pile end,the end-bearing pile is better than that of friction pile,the influence depth of post-grouting on the pile end is limited,the post-grouting should be mainly used to improve the deposit at pile end and the nearby soil layer of end-bearing pile;(5)postgrouting will not change the load transfer rule of super-long cast-in-place pile,and the pile shaft still needs to be gradually developed in layers,but the pile load-displacement relationship will become slower.In order to improve the pile bearing capacity and reduce the pile foundation settlement at the same time,post-grouting at the pile shaft can be preferred for super-long cast-in-place pile first.
作者
詹伟达
欧红亮
王幸
娄学谦
刘日炜
ZHAN Wei-da;OU Hong-liang;WANG Xing;LOU Xue-qian;LIU Ri-wei(CCCC Fourth Harbor Engineering Co.,Ltd.,Guangzhou Guangdong 510290,China;CCCC Fourth Harbor Engineering Institute Co.,Ltd.,Guangzhou Guangdong 510230,China)
出处
《公路交通科技》
CSCD
北大核心
2023年第9期141-150,共10页
Journal of Highway and Transportation Research and Development
关键词
桥梁工程
承载特性
对比研究
后注浆
自平衡试验
超长灌注桩
bridge engineering
bearing characteristics
comparative study
post-grouting
self-balancing test
super-long cast-in-place pile
