土层性质及成孔机具对钻孔灌注桩孔径变化的影响  

A Study on the Effect of Soil Layer Nature and Drilling Machine on Variation of Cavity Diameter of Cast-In-Place Bored Piles

作　　者：鲁嘉 诸苕 黄安芳 李尚飞[1] 

机构地区：[1]同济大学岩土及地下工程教育部重点实验室地下建筑与工程系,上海200092 [2]上海隧道工程质量检测有限公司,上海200023 [3]广西建筑工程质量检测中心,南宁530001

出　　处：《建筑科学》2009年第9期90-94,共5页Building Science

基　　金：上海市重点学科建设项目资助(B308)

摘　　要：在成孔质量的各影响因素中,土层性质及成孔机具对孔径变化的影响最为显著。本文基于砂性土和粘性土自身性质的差异,以及常规钻机和旋挖钻机施工特性,结合工程现场成孔实测数据,通过对不同土层条件下孔径变化趋势的统计和分析,总结出孔径变化规律。结果表明:孔径沿深度分布大致呈缩小趋势,浅部土层性质不稳,孔径变化剧烈,易受各种因素影响而产生扰动,形成扩孔;常规钻机护壁性能好,成孔孔径变化稳定,而旋挖钻机护壁性能差,尤其在砂性土中易形成缩孔;粘性土自身性质稳定,缩孔效应不明显。砂土层的粘聚力甚小,更易出现松弛,导致土体侧向位移。Soil layer nature and drilling machine play the most important role in the factors which affect the quality of cavities. The paper states and analyzes the trend of variation of cavity diameter in different soil layers by use of measured data about diameter of cavities in engineering spots to summarize the rule and mechanism of variation of cavity diameter. The study results demonstrate as follows： The cavity diameter decreases as depth increases, and the diameter of cavities in shallow soil layer changes fiercely for its＇ quality is unstable, which will make the diameter of cavities expand with the perturbation of the soil layer as a result of effect of many factors ; General drilling machines have good performance in shaft wall protection by drilling mud, so the variation of cavities retains steady, whereas rotary drilling machines have bad performance in shaft wall protection by drilling mud, especially in sand it will come into contraction cavities; The quality of cohesive soil is stable so that the contraction cavities effect is not obvious. Meanwhile, the cohesive force C of sand is small, which will produce relaxation to induce lateral displacement.

关 键 词：成孔检测 卸荷 孔径变化 土层性质 缩孔 

分 类 号：TU473.1[建筑科学—结构工程] TU473.14[建筑科学—土工工程]