2023年人工挖孔墩基础方案.doc

人工挖孔墩根底方案 马山旧城改造一期工程a地块人工挖孔灌注墩施工方案 一、工程概况·························································································1二、施工准备·························································································3 2.1材料及主要机具：········································································32.2作业条件：··················································································4三、操作工艺·························································································4四、质量标准·························································································9 4.1保证工程：················································································104.2根本工程：················································································104.3允许偏差工程·············································································10五、成品保护························································································11六、应注意的质量问题············································································11九、主要平安技术措施············································································18十、质量记录························································································20十一、墩孔塌孔应急预案·········································································20 11.1目的························································································2023.2适用范围·················································································2023.3相关文件·················································································2023.4工程概况、危险目标确实定及潜在危险性的评估······························2111.5应急救援指挥领导小组机构、职责················································2111.6救援专业队伍的分工··································································2211.7对内外的交流···········································································2211.8应急设备·················································································2311.9伤害人员的抢救措施··································································2311.10有关规定················································································24 第一章工程概况 1.1工程概况 本工程为马山工业园旧城改造一期工程a地块，本工程位于XX市XX县区谭鑫培路与马山路交汇处。本子项位于a地块，a地块包含a1X、a2两栋3层的商业裙房，a3X为29层的住宅，a4X为31层的住宅。各主楼尺寸如下： 1、地下室平面尺寸为189.7mx139.9m，地下室层数为两层，负二层结构层高3.85m，负一层结构层高5.7m。 2、a1X平面尺寸为80.25mx107.5m，一层层高5.7m，二层层高5.5m，三层层高11.05m，建筑总高度22.3m。 3、a2X平面尺寸为100.55mx107.5m，一层层高5.7m，二层层高5.5m， 三层层高5.15m，建筑总高度16.4m。 4、a3X平面尺寸为58.22mx14.60m，裙房局部层高同a1X，标准层层高为2.95m，建筑总高度99.8m，属a类高度高层建筑。 5、a4X平面尺寸为58.22mx14.60m，裙房局部层高同a2X，标准层层高为2.95m，建筑总高度99.85m，属a类高度高层建筑。 人工挖孔墩位于a4X楼b2~b5/ca~aa区域。根据本工程根底勘察报告并结合现场实际试挖情况，根底持力层（强风化粉砂泥质岩）深度在2.5~5m左右，根据设计要求采用墩径φ1000圆形（扩底墩）人工挖孔墩加钢筋混凝土支护体系。进入持力层≥500mm，墩身采用c35级混凝土。根底等级：甲级1.2地质概况 1.2.1根据武汉地质工程勘察院提供的马山工业园旧城改造一期（a地块）工程岩土工程勘察报告，本工程场地内地层按其成因、结构特征及强度自上而下共分为6层，上层滞水水位0.5m~2.6m（18.23~21.69m）各岩土层的地质时代及成因类型、顶板埋深、顶板标高、厚度、空间分布、岩土特征、工程性质详见下表： 场地土类型和场地类别场地土层主要为杂填土、粉质粘土、淤泥粘土、含角砾粘土。根据勘察经验场地土质fak大于150kpa。 第二章施工准备 2.1材料及主要机具 2.1.1水泥。宜采用325号矿渣硅酸盐水泥。 2.1.2砂：中砂或粗砂，含泥量不大于5%。石子：粒径为0.5～3.2cm的卵石或碎石。墩身混凝土采用商品混凝土。水：用自来水 2.1.6钢筋。钢筋的级别、直径必须符合设计要求，有出厂证明书及复试报告。 2.1.8模板。组合式木模，弧形工具式木模二块拼装。卡具、挂钩和零配件。木板、木方等。 2.2作业条件： 2.2.1开挖前场地应完成三通一平。地上、地下的电缆、管线、旧建筑物、设备根底等障碍物均已排除处理完毕。各项临时设施，如照明、动力、通风、平安设施准备就绪。 2.2.2熟悉施工图纸及场地的地下土质、水文地质资料，做到心中有数。 2.2.3按配套道路，挡墙施工总平面图，设置墩位轴线、定位点；墩孔四周撒灰线。测定高程水准点。放线工序完成后，办理预检手续。 2.2.4按设计要求分段制作好钢筋笼。 2.2.5在地下水位比较高的区域，先降低地下水位至墩底以下0.5m左右。 2.2.6人工挖孔操作的平安至关重要，开挖前应对施工人员进行全面的平安技术交底；操作前对吊具进行平安可靠的检查和试验，确保施工平安。 第三章操作工艺 3.1工艺流程： 人工挖孔墩施工流程如图01所示。 3.1.2放线定墩位及高程。在场地三通一平的根底上，依据建筑物测量控制网的资料和根底平面布置图，测定墩位轴线方格控制网和高程基准许点。确定好墩位中心，以中点为圆心，以墩身半径加护壁厚度为半径画出上部（即第一步）的圆周。撒石灰线作为墩孔开挖尺寸线。孔位线定好之后，必须经有关部门进行复查，办好预检手续后开挖。 3.1.3开挖第一节墩孔土方。开挖墩孔应从上到下逐层进行，先挖中间局部的土方，然后扩及周边，有效地控制开挖孔的截面尺寸。每节的高度应根据土质好坏、操作条件而定，一般以0.5～1m为宜。 3.1.4支护壁模板附加钢筋： 为防止墩孔壁坍方，确保平安施工，成孔设置井圈，其种类有素混凝土和钢筋混凝土两种。以现浇钢筋混凝土井圈为好，与土壁能紧密结合，稳定性和整体性能均佳，且受力均匀， 可以优先选用。当墩孔直径不大，深度较浅而土质又好，地下水位较低的情况下，也可以采用喷射混凝土护壁。护壁的厚度应根据井圈材料、性能、刚度、稳定性、操作方便、构造简单等要求，并按受力状况，以最下面一节所承受的土侧压力和地下水侧压力，通过计算来确定。护壁模板采用拆上节、支下节重复周转使用。模板之间用卡具、扣件连接固定，也可以在每节模板的上下端各设一道圆弧形的、用槽钢或角钢做成的内钢圈作为内侧支撑，防止内模因受力而变形。不设水平支撑，以方便操作。 第一节护壁以高出地坪150～200mm为宜，便于挡土、挡水。墩位轴线和高程均应标定在第一节护壁上口，护壁厚度按设计要求。 3.1.5浇筑第一节护壁混凝土。墩孔护壁混凝土每挖完一节以后应立即浇筑混凝土。人工浇筑，人工捣实，混凝土强度为c35，坍落度控制在100~120mm，确保孔壁的稳定性。 3.1.6检查墩位（中心）轴线及标高。每节墩孔护壁做好以后，必须将墩位十字轴线和标高测设在护壁的上口，然后用十字线对中，吊线坠向井底投设，以半径尺杆检查孔壁的垂直平整度。随之进行修整，井深必须以基准点为依据，逐根进行引测。保证墩孔轴线位置、标高、截面尺寸满足设计要求。 3.1.7架设垂直运输架。第一节墩孔成孔以后，即着手在墩孔上口架设垂直运输支架。支架要求搭设稳定、牢固。 3.1.8安装电动葫芦或卷扬机。在垂直运输架上安装滑轮组和电动或穿卷扬机的钢丝绳，选择适当位置安装卷扬机。因现场设计为墩根底， 所以采用木吊架借助粗麻绳作提升工具。地面运土用手推车或翻斗车。 3.1.9安装吊桶、照明、活动盖板、水泵和通风机。 3.1.9.1在安装滑轮组及吊桶时，注意使吊桶与墩孔中心位置重合，作为挖土时直观上控制墩位中心和护壁支模的中心线。 3.1.9.2井底照明必须用低压电源（36v、100w）、防水带罩的平安灯具。墩口四周设围护栏。 3.1.9.3当墩孔深大于10m时，应向井下通风，加强空气对流。必要时输送氧气，防止有毒气体的危害。操作时上下人员轮换作业，墩孔上人员不得离岗，密切注视观察墩孔下