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(廣州北站開發(fā)建設(shè)有限公司,廣州 510800)

摘要: 巖溶地區(qū)厚覆砂層樁基采用常規(guī)沖孔工藝無法對(duì)塌孔進(jìn)行有效控制,存在成本大、施工周期長且可能無法成孔的風(fēng)險(xiǎn).經(jīng)分析,本工程有 38 根樁平均樁長 45.32m,最長樁長 66.55m,樁基上覆砂層與溶洞累計(jì)高度之和平均 30.51m,是樁基施工的重點(diǎn).對(duì) 2 種備選施工方案的工期與經(jīng)濟(jì)進(jìn)行定量分析.分析結(jié)果表明,可循環(huán)長鋼護(hù)筒跟進(jìn)法方案相較全套管全回轉(zhuǎn)鉆機(jī)灌注樁成套技術(shù)方案,工期至少節(jié)約 28d、造價(jià)可節(jié)省 487.62 萬元,且比常規(guī)沖孔工藝方案僅增加 193.26 萬元.采用可循環(huán)長鋼護(hù)筒跟進(jìn)法作為施工方案,實(shí)踐中工期節(jié)約 32d、造價(jià)節(jié)省499.52 萬元.最后,總結(jié)了該施工方案的長鋼護(hù)筒制作、埋設(shè)深度、振打和起拔,溶洞預(yù)處理、施工中不良地質(zhì)處理、混凝土澆筑等施工關(guān)鍵技術(shù).

關(guān)鍵詞: 巖溶;厚覆砂層;方案比選;長鋼護(hù)筒;樁基施工

中圖分類號(hào):TU473.1+4 文獻(xiàn)標(biāo)志碼:A 文章編號(hào):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:陳東波,學(xué)士,工程師,主要從事建筑工程技術(shù)與管理,Email: 648519361@ qq. com.

[引用本文] 陳東波. 巖溶地區(qū)厚覆砂層樁基施工方案比選及實(shí)例分析[ J]. 建筑結(jié)構(gòu),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.