地下水活动对灌注桩完整性的影响研究  

Research on the Influence of Groundwater Activity on the Integrity of Cast-in-place Piles

作　　者：常聚友[1] 谭屹 赵永浩 赵小强 蔡佳茹 常超 CHANG Juyou;TAN Yi;ZHAO Yonghao;ZHAO Xiaoqiang;CAI Jiaru;CHANG Chao(China Railway Eryuan Engineering Group Co.Ltd,Chengdu,Sichuan 610031,China;China Construction Fifth Engineering Division Corporation,Changsha,Hunan 410000,China)

机构地区：[1]中铁二院工程集团有限责任公司,成都610031 [2]中国建筑第五工程局有限公司,长沙410000

出　　处：《铁道工程学报》2021年第4期33-37,共5页Journal of Railway Engineering Society

摘　　要：研究目的:《铁路工程基桩检测技术规程》(TB 10218—2019)中3.1.4规定:桩身完整性检测对于反射波法、声波法的检测结果,有怀疑或争议时,采用钻芯法验证;但现场有时验证的芯样结果与反射波法、声波法的检测结果不吻合,分析是与地下水活动影响有关,由此有必要就反射波法、声波法、钻芯法的检测结果结合工程地质,进行地下水活动对灌注桩完整性的影响研究。研究结论:(1)软土地层由于浅部地下水活动和深部粉砂层承压水的作用,使受力土层影响的细颗粒土下沉而孔隙度增大且不稳定;(2)桩机械施工使浅部稳定水位处的土层和深部承压水的粉砂层易坍塌呈扩孔,扩孔上方的成孔一侧土体临空失稳向下变形,且靠近钢筋笼方向变形较大;(3)桩灌注混凝土在上升过程中首先进入扩孔处,产生水平推力,促使失稳土体涌入钢筋笼,随着灌注混凝土的上升推力大于涌入土体的临界重力,混凝土切割部分涌入土体,共同上升,未被切割涌入土体的混凝土侧留有擦痕,使其桩周缩径露筋,且桩中心范围混凝土致密,为明显Ⅲ类不合格桩;(4)钻芯验证孔位应布设在其缺陷对应桩周靠近钢筋笼的内侧处;(5)本研究成果可为铁路、公路等领域的软土地区反射波法、声波法、钻芯法检测灌注桩的完整性研究提供参考。Research purposes:According to 3.1.4 of the Technical Specification for Testing of Railway Piles(TB 10218-2019),when there is doubt or dispute about the detection results of the reflected wave method and the acoustic wave method,the core-drilling method is used to verify;The core sample results sometimes verified in the field do not agree with the test results of the reflected wave method and the acoustic wave method,which is related to the influence of groundwater activities through analysis.Therefore,it is necessary to study on the influence of groundwater movement on the integrity of cast-in-place pile based on the testing results of reflected wave method,acoustic wave method and core-drilling method combined with engineering geology.Research conclusions:(1)Because of the action of shallow groundwater level and deep confined water in silty sand layer,the fine-grained soil affected by the stressed soil layer sinks and its porosity increases and is unstable.(2)Due to the mechanical construction of piles,the soil layer at the shallow stable water level and the silty sand layer at the deep confined water are easy to collapse and expand the hole,and the soil mass on the pore-forming side above the hole is unstable and deform downward near the reinforcement cage.(3)The ascending concrete of pile grouting first enters into the hole reaming and returns to produce horizontal thrust,which causes the unstable soil to pour into the reinforcement cage,and then the ascending thrust of grouting concrete is greater than the critical gravity of pouring into the soil,the concrete cutting part of the pile rises into the soil,and the concrete side of the non-moving pile has a scratch mark,which makes the diameter around the pile exposed,and the concrete in the center of the pile is dense,which is obviously the unqualified pile of class III.(4)The hole location of core drilling verification shall be located near the inner side of reinforcement cage around the pile corresponding to the defect.(5)The research results can provide a r

关 键 词：黏土 粉质黏土 粉砂 地下水 缩径露筋 钻芯 擦痕 

分 类 号：TU473.16[建筑科学—结构工程]