(广州北站开发建设有限公司,广州 510800)

摘要: 岩溶地区厚覆砂层桩基采用常规冲孔工艺无法对塌孔进行有效控制,存在成本大、施工周期长且可能无法成孔的风险.经分析,本工程有 38 根桩平均桩长 45.32m,最长桩长 66.55m,桩基上覆砂层与溶洞累计高度之和平均 30.51m,是桩基施工的重点.对 2 种备选施工方案的工期与经济进行定量分析.分析结果表明,可循环长钢护筒跟进法方案相较全套管全回转钻机灌注桩成套技术方案,工期至少节约 28d、造价可节省 487.62 万元,且比常规冲孔工艺方案仅增加 193.26 万元.采用可循环长钢护筒跟进法作为施工方案,实践中工期节约 32d、造价节省499.52 万元.最后,总结了该施工方案的长钢护筒制作、埋设深度、振打和起拔,溶洞预处理、施工中不良地质处理、混凝土浇筑等施工关键技术.

关键词: 岩溶;厚覆砂层;方案比选;长钢护筒;桩基施工

中图分类号:TU473.1+4 文献标志码:A 文章编号:1002-848X(2022)17-0139-06

DOI:10.19701 / j.jzjg.20211839

Comparison selection and case analysis on construction schemes of thick sand layer coveredpile foundation in karst district

CHEN Dongbo

(Guangzhou North Railway Station Development and Construction Co. ,Ltd. ,Guangzhou 510800,China)

Abstract: The conventional punching technology would not effectively control the hole collapse of thick sand layer coveredpile foundation in karst district,which has the risk of high cost,long construction period and the possibility of failure toform a hole. After analysis,there are 38 piles with an average pile length of 45.32m and the longest pile length of 66.55min the project,and the average cumulative height sum of the overlying sand layer and karst cave is 30.51m,which is thekey point of pile foundation construction. The construction period and economy of the two alternative construction schemeswere quantitatively analyzed. The analysis results show that compared with the complete technical scheme of cast-in-placepile of full casing rotary drilling rig,the scheme of recyclable long steel casing follow-up method can save at least 28 days,save RMB 4.876 2 million yuan in cost,and only increase RMB 1.932 6 million yuan compared with the conventionalpunching technology scheme. The recyclable long steel casing follow-up method can be adopted as construction plan. Inpractice,the construction period was saved by 32 days and the cost was saved by RMB 4.995 2 million yuan. Finally,thekey construction technologies of the construction scheme were summarized,such as the fabrication,burial depth,vibrationand pulling of long steel casing,karst cave pretreatment,adverse geological treatment in construction,concrete pouring andso on.

Keywords:karst;thick sand layer;comparison selection of scheme;long steel casing;pile foundation construction

第一作者:陈东波,学士,工程师,主要从事建筑工程技术与管理,Email: 648519361@ qq. com.

[引用本文] 陈东波. 岩溶地区厚覆砂层桩基施工方案比选及实例分析[ J]. 建筑结构,2022,52(17):139-144.CHEN Dongbo. Comparison selection and case analysis on construction schemes of thick sand layer covered pile foundationin karst district[J]. Building Structure,2022,52(17):139-144.