提高灌注桩质量QC成果

提高钻孔灌注桩质量 常州三建建设有限公司 307 项目部 二〇一二年十月 目录 一、工程概况···········································································································2 二、小组概况·············································································································3 三、选题理由·············································································································4 四、现状调查·············································································································4 五、课题活动目标·····································································································5 六、要因分析·············································································································5 七、制定对策·············································································································7 八、对策实施·············································································································7 九、第二次 PDCA 循环 ···························································································8 十、QC 活动实施效果····························································································12 十一、巩固措施·······································································································12 十二、存在问题和今后打算················································································12 十三、体会·············································································································13 -1- 提高钻孔灌注桩质量提高钻孔灌注桩质量 一、工程概况一、工程概况 钻孔灌注桩是采用钻机钻孔水下灌注混凝土成桩的一种桩基施工工艺。它采用 冲击钻、旋挖钻等钻机钻孔，钻孔深度达到设计标高后进行清孔，根据混凝土与水 的比重不同，利用导管灌注水下混凝土成桩。由于灌注桩支护比土钉墙支护安全可 靠，而且承载力也较大，在我国基础设施建设中得到非常广泛应用。 荷花池街道综合服务中心工程位于常州市钟楼区港龙尚城北侧，西新桥二村 农贸市场东侧，主体结构为2~6 层的办公楼，地下车库为1~1.5 层，基础形式为 混凝土预制桩，场地平均标高为黄海 2.9 米，基坑东侧道路标高为 3.6 米，基坑开 挖深度为 4.45~6.50 米。支护桩桩径为φ800，有效桩长在7.45-15.5 米之间；为 确保工程质量和工期要求，结合我公司的装备及施工经验，本工程施工拟采用 GPS-10（俗称 300 型）型钻机正循环钻进成孔、清孔、水下砼灌注成桩工艺 本基坑±0.00 为黄海高程 4.20m，场地地坪平均标高 2.90m，东侧道路标高 3.60m，基底标高-1.55m~-3.60m，则挖深 4.45-6.50m。本基坑支护深度影响范 围内土层为：①杂填土；②1 粉质粘土；②2 粉土；②3 淤泥质粉质粘土；②4 粉质 粘土；⑤1 粉土夹粉砂等。本基坑的特点： (1) 本基坑开挖深度范围内土层分布不均匀，东侧、北侧分布有较厚的②2 粉土。 (2) 本工程周边临近道路，各市政管线较多：雨污水管分布四周道路中间，管径约 1m，埋深约 2m;东南侧煤气管沿围墙布设，埋深约 2m。 (3)基底标高为黄海-1.55m~-3.60m，揭露的土体为②2 粉土。 在工期紧迫的情况下，如何快速、优质地完成桩基的施工任务，克服杂填土及 -2- 淤泥质土易塌孔的现象，合理组织人员机具配置，加快桩基施工进度，严格控制工 程质量非常重要。为此，项目成立了 QC 小组，科学攻关，加强工序质量控制。 二、小组概况二、小组概况 QC 小组成员概况表 （表 1） 小 组 名 称 成 立 时 间 小 组 类 型 课 题 名 称 文化程 度 注册时间 活动时间 提高钻孔灌注桩质量 接受 TQC教育时间 (h) 注册号 序号姓名性别 年 龄职务组内分工 1 2 3 4 5 6 7 -3- 8 9 活 动 情 况 -4- 三、选题理由三、选题理由 荷花池街道综合服务中心工程的质量目 标是：确保工程达到市金龙杯。 课题：课题： 提 高 桩基质量直接影响了基坑的安全。 钻 孔 灌 注 桩 质 克服地表杂填土易塌孔和漏浆等现象。 量 四、现状调查四、现状调查 某月 某 日，我们对现场正在施工的钻孔桩质量情况进行调查分析，调查结 果表明： 1、在钻孔桩施工中， 容易出现塌孔现象，常州市中元建设工程勘察院有限公司 的图纸中规定：桩基应严格清孔，桩底清孔后的沉渣厚度不得大于 15 厘米。 2、钻孔过程中容易出现漏浆现象，致使钻进过程中注入泥浆不起作用。 3、孔口易出现塌陷，出现蘑菇桩头。 4、桩头质量不好，浮浆过多。 根据以上调查， 我们 QC 小组作出了钻孔桩施工质量问题调查统计表 （见表 2） ： 钻孔灌注桩施工质量调查统计表 -5- （表 2） 序号 1 2 3 4 5 项目 漏浆 桩头浮浆多 塌孔 蘑菇桩头 其它 合计 频数 9 6 2 2 1 20 频率% 45 30 10 10 5 100 累计频数 % 45 75 85 95 100 图一：质量问题排列图 频数（次）N=20 20 18 16 14 12