泥质粉砂岩地区钻孔灌注桩沉渣质量事故分析与处理  

Treatment of Cast-in-place Pile Foundation Bottom Sediment Accident in Muddy Silt-stoneRegion

作　　者：王延该[1] WANG Yan-gai(Hubei Urban Construction Vocational And Technology College,Wuhan 430205)

机构地区：[1]湖北城市建设职业技术学院,武汉430205

出　　处：《广州建筑》2020年第5期23-27,共5页GUANGZHOU ARCHITECTURE

摘　　要：本文介绍了泥质粉砂岩地区桩基事故的处理方法和处理效果。抽芯试验结果表明,桩端沉渣最大达150cm,不满足规范要求,采用抽芯法扩大验证,检测结果仍不理想。泥质粉砂岩具有遇水软化特性,如成桩桩端质量不合格,承载力恐难以达到设计要求,故而这批工程桩被视作事故桩。经事故处理方案比选,最终选用钻孔抽芯洗孔后低压慢速注浆法进行桩底加固处理,并在处理后选择了三根桩进行静载试验,试验结果表明,桩基单桩承载力均能满足设计要求,说明钻孔洗孔后低压慢速注浆法对处理泥质粉砂岩桩端沉渣有效可行。This paper introduced the method for the treatment of a cast-in-place pile foundation accident in muddy silt-stone region.Pile cap foundation was adopted in this project,and the pile tip embedded into the intermediary weathered muddy silt-stone for the length of 1~3m.Core drilling tests of several piles were conducted to inspect the pile integrity quality and the bottom sediment,and the sediment at pile bottom was found to be up to 150 cm,through the pile body integrity quality was rather good.Five expansion tests reached the same conclusion.Since the pile bottom sediment was close to mud,the allowable axial bearing capacity of these piles might not fulfill the design requirements.Hence,these piles were treated as accident piles.After several technical proposals comparison,coring and grouting method was finally adopted.Unlike common post-grouting method,an improved method was utilized in this project.Clean water was first injected to the intake to wash the pile bottom sediment until the water from the delivery port turned to be clean,and then cement slurry was grout.Load test results indicated that this method hasachieved good results.After the treatment,the ultimate pile bearing capacity could meet the design requirements,which indicates that coring and grouting method is effective for the treatment of soft bottom sediment in muddy silt-stone region.

关 键 词：泥质粉砂岩 灌注桩 桩基事故处理 桩端沉渣 钻孔注浆法 

分 类 号：TU473.1[建筑科学—结构工程]