围堰与基坑开挖专项施工方案

Xxxxx公司专项施工方案-1-xxxxx工程现浇箱涵工程围堰与基坑开挖专项施工方案Xxxxx公司专项施工方案-2-目录一、工程概况·····································································································3二、施工组织和管理机构·················································································4三、围堰与基坑开挖施工工艺流程·································································4四、施工进度计划·····························································································5五、围堰与基坑开挖施工要点·········································································5六、土围堰设计计算·························································································8七、基坑边坡稳定设计计算·············································································8八、安全保证措施·····························································································8九、质量保证措施·····························································································10十、文明施工措施·····························································································11十一、预防伤害安全生产事故应急救援预Xxxxx公司专项施工方案-3-案·················································12十二、附件·········································································································17附件1··················································································································17附件2··················································································································20附件3··················································································································23附件4··················································································································24附件5··················································································································25Xxxxx公司专项施工方案-4-一、工程概况Xxxxxx工程共有箱涵1座，本箱涵为4.0×4.0m双孔箱涵，中心里程桩号K0+550，箱涵中心线与设计混合车道中心线正交，涵长16.6m。采用整体式钢筋混凝土涵身，扶壁式挡土墙翼墙。箱涵净孔尺寸为4.0×4.0m，箱涵宽9.2m，长16.6m。顶板厚40cm，底板厚40cm，中腹板厚40cm，边腹板厚40cm，涵身为现浇C30混凝土。底板下缘浇注10cmC15混凝土垫层，其下为10cm碎石垫层。箱涵外侧（东侧）设置水平开启的闸门，闸门与箱涵的连接采用分体式，相互不影响先后施工，箱涵所在河道宽18m，道路两边河岸做石砌驳岸，东侧上游有鱼塘和排涝站，设有闸门。箱涵基坑开挖拟采用先上游后下游围堰，后抽水开挖的方式，1、围堰：施工围堰采用填筑碾压硬塑粘土，围堰分上游及下游挡土围堰。填土分层夯实，围堰内底距离箱涵结构的距离不小于5m，以保证箱涵施工有足够的工作面。上下游围堰顶宽均取3.5m，围堰外侧迎水面坡度为1:2，围堰内侧边坡为1:1.5，水深为2.367m，围堰高超出最高水位50cm。2、基坑开挖：基坑开挖采用人工配合机械开挖，基坑安全等级三级，为保证边坡稳定，采用放坡开挖，采用2级放坡，坡度为1:1，中间设1.5m宽平台。箱涵底标高为-1.78，原地面标高为2.88，挖深为4.5m，考虑安全及后期路基施工要求等因素，先在河道边每边清表60cm，长20m，使基坑深度为3.9m。上级边坡高度2m，下级1.9m。边坡土质从上到下为：（1）第一层素填土，厚度1-3m，结构松散，强度低，土质不均。（2）第二层粉质粘土，可塑-软塑，中等压缩性，为一般强度地基土，厚度0-1.1m。（3）第三层淤泥质粉质粘土，流塑，高压缩性，低强度地基土，厚度为0.7-1.9m。（4）第四层粘土，可塑，中等压缩性，中等强度地基土，厚度3.5m-4.9m。箱涵地基为第四层粘土层，边坡为1—4层。Xxxxx公司专项施工方案-5-二、施工组织和管理机构三、围堰与基坑开挖施工工艺流程1、围堰施工工艺流程施工准备（路电和物资机械人员等资源准备）→上游截流，下游放空→抽排积水→测量放线→清理淤泥→分层填筑夯实堰体→清理整平围堰坡面→整平堰顶。2、基坑开挖施工工艺流程原地面清表→测量放线→上层土方开挖→中间工作平台施工→下层层土方开挖→人工修项目经理项目副经理项目技术负责人测量工程师材料员安全员资料员质检工程师钢筋班组其他综合班组模板班组混凝土班组项目负责人Xxxxx公司专项施工方案-6-整边坡→坑底的土方开挖→挖排水沟→垫层施工四、施工进度计划见附件3。五、围堰与基坑开挖施工要点1、编制依据（1）本工程的施工招标文件及招标答疑纪要；（2）本工程的施工图纸；（3）建筑安全检查标准及有关安全生产、文明施工的规定；（4）施工勘察资料；（5）业主要求工程质量目标；（6）《建筑地基基础设计规范》（GB50007-2002）；（7）《建筑基坑支护技术规程》（JTJ319-99）；（8）《建筑地基处理技术规范》（JGJ79(J220)-2002）。2、测量放样围堰施工时，要测放出围堰的位置，要保证箱涵施工时的工作面。基坑开挖时要保证基坑的平面位置正确，开挖过程中要经常检测开挖位置以及开挖深度，开挖基坑底时要特别注意，坑底最后30cm应由人工开挖，所以测量要跟踪开挖。3、围堰施工要点：（1）施工准备①施工机械设备、物资机械配备情况表机械配备数量机械配备数量挖掘机（1m3）2台潜水泵（大口径）3台推土机1台铁锹30把自卸车（5T）5台照明灯具5盒硬塑粘土若干电缆电线若干电夯1台人工夯3台②电源要准备好，以供夜间施工照明及抽排水施工。Xxxxx公司专项施工方案-7-（2）截流协同建设单位与当地排涝站联系，采取上游截流一定时间，下游排空水流。（3）抽排消力池内积水准备用多台流量大以上污水泵抽排消力池内积水至下游河道内，尽快抽排完毕。（4）测量放线河道内淤泥清理完成后，测量放线；用白灰标示出围堰基础边线，（5）清理河道淤泥，用装载机铲运淤泥至下游。（6）分层填筑碾压堰体挖掘机挖装土方，5T自卸车运土至施工现场，装载机现场铲运土方，推土机推平后夯实。（7）清理整平围堰坡面人工清理整平堰体坡面，以保证坡面的顺直及坡度、平整度符合要求；（8）整平堰顶填筑夯实完成后，人工整平堰顶。3、基坑开挖施工要点：土方开挖由专人指挥，采取分层分段对称开挖，并严格遵循“分层开挖、严禁超挖”及“大基坑小开挖”的原则。当挖至标高接近基础底板标高时，边抄平边配合人工清槽，防止超挖，并按围护结构要求及时修整边坡及放坡，防止土方坍塌。坑底300mm土方采用人工清理，然后用挖机带走。主要分为两级开挖：（1）首先清除表面根植土60cm，使基坑深度为3.9m。采用挖掘机开挖，自卸汽车外运。（2）第一级为开挖深度为2.5m。开挖边坡坡度为1:1，采用1m3反铲挖掘机开挖，开挖时要分层开挖，开挖到2m后立即人工修整边坡。（3）第一级完成后，在坡底修整1.5m宽平台，然后挖掘机继续开挖第二级，采用1m3反铲挖掘机开挖，开挖时要分层开挖，开挖深度约1.9m，机械开挖1.6m，余下部分采用人工开挖。机械开挖完成后人工立即修整边坡。（4）人工突击挖除坑底30cm后，应避免坑底长时间暴漏，尽快进行下道工序施工，24小时内完成10cm碎石垫层施工。（5）开挖过程中，随时注意基坑四周的土质情况。当基坑沿顶面裂缝、坑壁松塌等影响基坑稳定时，立即加固支护。基坑四周用土堆成30cm高土坝，防止地面水流入基坑，冲刷坑壁，基坑底设置集水坑。基坑开挖成型后，周围外设置围栏，并用密目网封闭。同时在基坑周边以及施工临时便道设置警示标志。（6）基坑开挖及进行基础施工过程中，运土自卸汽车必须按既定的马道行走，基坑其他Xxxxx公司专项施工方案-8-方向10米范围不许任何机动车辆通过，防止动荷载引起坑壁塌方。10米外车辆通过时，需加强对坑壁监测。（7）挖掘机、自卸车、装载机等施工机械均已到场，并检查机械的性能、状态，符合施工要求，已经对操作人员进行了培训、交底。施工时现场配备3台挖掘机、3辆自卸汽车。（8）土方开挖技术质量要求①各层土方开挖应按要求放坡挖土，根据本工程的自然地基状况，挖机挖土放坡不得小于1（高）：1（宽），视基坑土质而定。②土方开挖和外运的过程中，基坑2m不得堆放土方和重物，基坑内挖出土方应及时外运。③挖到设计标高经“三检”后，立即请地质勘察单位、设计院等进行验槽确认，如遇杂填土或成分复杂、结构均匀性差时，应会同各方确定处理，之后应立刻进行垫层施工，以避免土体隆起、泡水和土体扰动。（9）人工捡底的方法基坑形成后根据已建立的建筑物轴线控制网和高程控制桩，将轴线标高引测于坑内，并在坑内建立临时轴线控制网，测放出基础垫层外框线，作为人工捡底的依据，人工捡底应采用锹镐进行开挖，开挖过程中应注意基底标高，防止超挖，人工开挖前应邀业主、监理、质监等部门进行验槽。（10）土方的运输和堆放①开挖基坑的土方，在场地有条件堆放时，一定留足回填需用的好土；多余的土方，应一次运走，避免二次搬运。②土方运至业主指定地点堆放。堆放场地内，将土方按土的类型分类堆放，即杂填土、素填土堆放在一起，粉质粘土、粉土堆放在一起，中砂堆放在一起，圆砾、卵石堆放一起，膨胀土单独堆放。（11）基坑内排水：本工程主要采用设明沟、集水井排水法。基坑内排水，采取在基坑底形成集水沟，在集水沟两端挖掘集水井，具体尺寸如下：集水沟呈倒梯形，上口宽400mm，下口宽300mm，低于坑底0.4m。集水低于坑底标高1m，，东侧、西侧转角处各做1000×1000×1000集水坑。每处集