灌注桩抗拔承载力不足分析及应对措施研究  

ANALYSIS OF INSUFFICIENT PULLOUT CAPACITY AND RESEARCH ON COUNTERMEASURES OF CAST-IN-PLACE PILES

作　　者：房江锋 张思祺 杜琦 FANG Jiangfeng;ZHANG Siqi;DU Qi(Shenzhen Hongyeji Geotechnical Co.,Ltd.,Guangdong Shenzhen 518000,China)

机构地区：[1]深圳宏业基岩土科技股份有限公司,广东深圳518000

出　　处：《低温建筑技术》2024年第12期66-71,共6页Low Temperature Architecture Technology

摘　　要：深圳地区由于花岗岩地层的地质特点及泥浆护壁工艺的影响,经常出现灌注桩抗拔承载力不足的现象。文中结合深圳地区花岗岩地层特点、钻孔扰动与卸荷、泥浆和清孔质量控制、桩身泥皮等影响因素,对灌注桩抗拔承载力不足的原因进行了研究。研究结果表明,花岗岩风化物具有明显的结构性,钻孔扰动与卸荷影响桩周土体的力学特征,从而降低桩侧土体的摩阻力;施工泥浆质量及泥浆循环管理不当,加剧了桩身泥皮的形成,而桩身泥皮对抗拔力的影响显著。对施工过程及深圳地区工程经验进行总结,建议优先采取加强施工泥浆质量和泥浆循环管理、清刷泥皮的方法,降低桩周泥皮的形成及对抗拔力的影响;在加强施工管理效果不佳的情况下,可采取挤扩支盘桩、扩底桩、注浆挤扩钻孔灌注桩、后注浆等施工工艺来保证灌注桩的抗拔承载力。In the Shenzhen area,due to the geological characteristics of granite strata and the influence of slurry wall construction techniques,there is often insufficient uplift bearing capacity of bored piles.This paper investigates the causes of inadequate uplift bearing capacity of bored piles,taking into account the granite formation characteristics in Shenzhen,drilling disturbance and unloading effects,slurry quality control,hole cleaning,and the formation of mud skin on the pile shaft.The study results show that granite weathered material has distinct structural characteristics,and drilling disturbance and unloading affect the mechanical properties of the surrounding soil,thus reducing the lateral resistance of the pile.Poor slurry quality and improper slurry circulation management exacerbate the formation of mud skin on the pile shaft,which significantly impacts uplift resistance.Based on a summary of the construction process and engineering experience in Shenzhen,the study recommends prioritizing the improvement of slurry quality and circulation management,as well as the cleaning of mud skin to reduce its formation and impact on uplift capacity.In cases where improved construction management is ineffective,alternative methods such as expanded base piles,grout-injection-expanded bored piles,and post-grouting techniques can be used to ensure sufficient uplift bearing capacity of the bored piles.

关 键 词：花岗岩风化物 钻孔灌注桩 抗拔承载力 桩侧土体摩阻力 

分 类 号：TU399[建筑科学—结构工程]