现浇混凝土桩冲击成孔孔底沉渣机理研究  

The Study on the Characteristics of Bottom Sediment in Cast-in-Place Concrete Pile with Impact Hole

作　　者：邓荣贵[1] 孙怡[1] 孟仁帆 程刚[1] 刘远程 王园园[1] DENG Ronggui;SUN Yi;MENG Renfan;CHENG Gang;LIU Yuancheng;WANG Yuanyuan(School of Civil Engineering,Southwest Jiaotong University,Chengdu 610031,China)

机构地区：[1]西南交通大学土木工程学院,成都610031

出　　处：《铁道标准设计》2022年第3期105-112,共8页Railway Standard Design

基　　金：国家自然科学基金项目(41272321)。

摘　　要：当前沉渣厚度的界定仍停留在经验阶段,其机理研究还不够完善。为此,利用模型试验方法对水下灌注混凝土桩底沉渣特性进行研究,得到桩孔泥浆重度、混凝土块体沉降速率的分布特征及沉渣上界面形态,并采用理论分析的方法提出沉渣形成的机理。研究结果表明:(1)桩孔中泥浆重度随深度增加而增大,增速呈现分段特征;(2)混凝土拌和料团块在桩孔泥浆中的沉降速率分为快速增加、近似恒速增加和急速减小至滞停3个阶段,混凝土模拟团块沉降速率和最终停滞深度与重度、粒径、形状规则程度呈现正相关;(3)沉渣上界面呈漏斗状,拌和料脱离导管口冲入泥浆内会将泥浆向周围排挤;(4)灌注桩孔底沉渣形成机理是一个多相流体介质和塑性体介质与工艺紧密相关的综合问题,准流体静定分析表明,水下现浇混凝土桩底是否形成沉渣与导管管径、料斗盛料量和桩孔深度有关。At present,the definition of sediment thickness is still in the empirical stage,and its mechanism research is not perfect.Therefore,this paper studies the characteristics of sediment at the bottom of underwater cast-in-place concrete pile with model test method,obtains the distribution characteristics of mud weight in pile hole,settlement rate of concrete block and interface morphology of sediment,and puts forward the mechanism of sediment formation by using theoretical analysis method.The results show that:(1)The gravity of the slurry in the pile hole increases with the increase of the depth,and the growth rate presents the characteristics of segmentation.(2)The settlement rate of the concrete mixture aggregates in the pile hole slurry can be divided into three stages:rapid increase,approximately constant increase and rapid decrease to stagnation.The settlement rate and final stagnation depth of the concrete simulation aggregates are positively related to the gravity,particle size and shape regularity.(3)The upper interface of the sediment is funnel-shaped,enabling the mixture to leave the pipe mouth and rush into the mud,which,in turn,push the mud around.(4)The formation mechanism of the sediment at the bottom of the cast-in-place pile is a comprehensive phenomenon,in which the multiphase fluid medium and plastic medium are closely related to the technology.The quasi hydrostatic analysis shows that whether the sediment is formed at the bottom of the underwater cast-in-place concrete pile is related to the pipe diameter,the material content of the hopper and the depth of pile hole.

关 键 词：现浇混凝土桩 沉渣厚度 沉降速率 模型试验 静力分析 

分 类 号：TU473.1[建筑科学—结构工程] U445.551[建筑科学—土工工程]