目 录
1编制目的 ····························································································· 02 2编制依据 ····························································································· 02 3编制内容 ····························································································· 02 4适用范围 ····························································································· 02 5作业准备 ····························································································· 03 5.1测量定位 ························································································· 03 5.2场地清理及钻孔平台 ······································································ 03 6作业过程 ····························································································· 03 6.1泥浆制备 ························································································· 03 6.2埋设护筒 ························································································· 04 6.3钻孔定位 ························································································· 04 6.4钻进成孔 ························································································· 04 7质量通病的预防及采取的应对措施 ·················································· 06 7.1坍孔 ································································································· 06 7.2钻孔偏斜 ························································································· 07 7.3扩孔和缩孔 ····················································································· 07 8施工注意事项 ····················································································· 08
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钻孔桩旋挖钻机钻进作业指导书
1编制目的
为进一步规范现场施工作业，明确钻孔桩旋挖钻机钻进作业的工艺流程、操作要点和相应的工作标准，指导、规范旋挖钻机钻进作业施工。 2编制依据
《铁路桥涵施工规范》（TB10203-2002）
《铁路桥涵工程施工质量验收标准》（TB10415-2003 ） 《城市桥梁工程施工与质量验收规范》（CJJ2-2008） 《公路桥涵施工技术规范》（JTJ/T F50-2011） 《铁路桥涵工程施工安全技术规程》（TB10303-2009） 3编制内容
钻孔桩旋挖钻机钻进作业准备、作业过程、质量通病预防及措施、施工注意事项。 4适用范围
旋挖钻机是一种多功能、高效率的灌注桩成孔设备，利用钻杆和钻斗的旋转，以钻斗自重并加液压作为钻进压力，使土屑装满钻斗后提升钻斗出土。通过钻斗的旋转、挖土、提升、卸土和泥浆臵换护壁，反复循环而成孔。其特点是工作效率高、施工质量好、尘土泥浆污染少，尤其适用于城市桩基施工。
旋挖钻机一般适用粘土、粉土、砂土、淤泥质土、人工回填土及含有部分卵石、碎石的地层，借钻具自重和钻机加压力，耙齿切入土
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层，在回转力矩的作用下钻斗同时回转配合不同钻具，适应于干式（短螺旋）、湿式（回转斗）及岩层（岩心钻）的成孔作业。根据不同的地质条件选用不同的钻杆、钻头及合理的斗齿刃角。对于具有大扭矩动力头和自动内锁式伸缩钻杆的钻机，可以适应微风化岩层的施工。 5作业准备 5.1测量定位
施工前必须根据设计图纸，按照坐标逐个的放出钻孔桩的具体孔位，并做好明确标识。 5.2场地清理及钻孔平台
在施工前应平整场地、清除杂物。钻机的底座不能臵于不坚实的填土上，必要时进行换填和加铺钢板处理，防止钻进过程中因旋挖钻机自重对土体的挤压引起地基沉陷导致偏孔或者通过土体对护筒造成挤压引起偏孔。 6作业过程 6.1泥浆制备
现场设泥浆池（含回浆用沉淀池及泥浆储备池）一般为钻孔容积的1.5～2.0倍，要有较好的防渗能力。在沉淀池的旁边设臵渣土区，沉渣采用反铲清理后放在渣土区，保证泥浆的巡回空间和存储空间。制备泥浆可以采用泥浆搅拌机和水力搅拌器两种。使用粘土粉造浆时最好用水力搅拌器，使用膨润土造浆时用泥浆搅拌机。 护壁泥浆再生处理：施工中采用重力沉降除渣法，即利用泥浆与土渣的相对密度差使土渣产生沉淀以排除土渣的方法。现场设臵回收泥浆池用作回收
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护壁泥浆使用，泥浆经沉淀净化后，输送到储浆池中，在储浆池中进一步处理（加入适量纯碱和CMC改善泥浆性能）经测试合格后重复使用。
6.2埋设护筒
护筒的埋设是旋挖作业中的关键。桩基定位后，根据桩定位点拉十字线钉放四个控制桩，以四个控制桩为基准埋设钢护筒，以保护孔口防止坍塌，形成孔内水头和定位导向。护筒通常选用16mm厚钢板卷制而成，护筒内径为设计桩径+20～40cm，高度2.0m，上部开设2个溢浆孔，护筒埋设时，由人工、机械配合完成，主要利用钻机旋挖斗将其静力压入土中，其顶端应高出地面30cm左右，并保持水平，埋设深度1.7 m，护筒中心与桩位中心的偏差不得大于5cm（对深水基础中埋设的护筒可放宽至8cm）。护筒埋设要保持垂直，倾斜度不大于1％。 6.3钻孔定位
在桩位复核正确，护筒埋设符合要求，护筒、地坪标高已测定的基础上，钻机才能就位；桩机定位要准确、水平、垂直、稳固,钻机导杆中心线、回旋盘中心线、护筒中心线应保持在同一直线。旋挖钻机就位后，利用自动控制系统调整其垂直度，钻机安放定位时，要机座平整，机塔垂直，转盘（钻头）中心与护筒十字线中心对正，注入稳定液后，进行钻孔。 6.4钻进成孔
钻孔前必须检查钻头保径装臵，钻头直径、钻头磨损情况，施工
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过程中对钻头磨损超标的及时更换；根据土层情况正确选择钻斗底部切削齿的形状、规格和角度；根据护筒标高、桩顶设计标高及桩长，计算出桩底标高，以便钻孔时加以控制。
钻机就位时，必须保持平整、稳固，不发生倾斜。为准确控制孔深，应备有校核后钢丝测绳，并观测自动深度记录仪，以便在施工中进行观测、记录。钻进过程中应经常检查钻杆垂度，确保孔壁垂直。钻进过程中必须控制钻头在孔内的升降速度，防止因浆液对孔壁的冲刷及负压而导致孔壁塌方。钻进成孔过程中，根据地层、孔深变化，合理选择钻进参数，及时调制泥浆，保证成孔质量。在进入沙层和卵石层时，应适当减慢进尺速度，提高泥浆的稠度，减小每个钻进回次的进尺量，保证孔壁稳定。钻进施工时，利用正铲及时将钻渣清运，保证场地干净整洁，利于下一步施工。钻进达到要求孔深停钻后，注意保持孔内泥浆的浆面高程，确保孔壁的稳定。
成孔中，按试桩施工确定的参数进行施工，设专职记录员记录成孔过程的各种参数，如加钻杆、钻进深度、地质特征、机械设备损坏、障碍物等情况。记录必须认真、及时、准确、清晰。
钻孔过程中根据地质情况控制进尺速度：由硬地层钻到软地层时，可适当加快钻进速度；当软地层变为硬地层时，要减速慢进；在易缩径的地层中，应适当增加扫孔次数，防止缩径；对硬塑层采用快转速钻进,以提高钻进效率；砂层则采用慢转速慢钻进并适当增加泥浆比重和粘度。
孔底沉淤控制：旋挖钻斗的切削、提升上屑的机理是通过钻斗把
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