锦屏一级水电站水位观测站竖井开挖钢支架施工方案

雅砻江锦屏一级水电站水位观测站工程合同编号：JPIC-G201214锦屏一级水电站水位观测站竖井开挖钢支架施工方案批准：审核：编制：葛洲坝集团第二工程有限公司锦屏一级水电站水位观测站工程施工项目部目录一、工程概况····················································································11.1概述···························································································11.2钢支架设计··················································································1二、编制依据····················································································1三、钢支架架设方案···········································································13.1材料准备·····················································································13.2安装过程·····················································································2四、钢支架受力检算···········································································34.1横梁···························································································34.2立杆···························································································4五、卷扬机安装·················································································55.1卷扬机地锚施工············································································55.2安装卷扬机及承载钢丝绳································································55.3钢丝绳受力计算············································································6七、操作使用及注意事项····································································7八、使用与管理·················································································78.1安装后使用前的验收应符合下列规定·················································78.2使用提升机时应符合下列规定··························································88.3提升机使用中应进行经常性的维修保养符合下列规定····························9九、钢支架安装、使用及拆除安全措施··················································99.1钢支架安装安全措施······································································99.2钢支架使用安全措施·····································································109.3钢支架拆除工作安全要求·······························································111锦屏一级水电站水位观测站竖井开挖钢支架施工方案一、工程概况1.1概述锦屏一级水位观测站竖井开挖包括三滩一级水位观测站和三滩二级水位观测站两个竖井，竖井为圆形断面，开挖内径为2.7m，开挖总长度为86m。竖井井身开挖前在井口设置钢支架配3T的卷扬机作为提升设备,采用钢板及型钢自制容量0.4m3的装碴筒装碴。1.2钢支架设计单个竖井钢支架高度为4m，横梁有效长度4m，共设置1台JK-3卷扬机和一个滑轮组。滑轮组布置在钢支架横梁跨中，钢支架及卷扬机根据现场情况布置。钢支架共设2根Ф108*5mm钢管立柱，钢支架固定在钢筋砼支墩上，以支撑钢支架的自重及吊运重物时所发生的一切荷载，每个支墩的尺寸为0.5x0.5x0.5m，为现浇C25砼，在基础支墩上预埋10mm厚钢板，以便钢支架钢管立柱与基础支墩牢固连接，钢板平面尺寸为300x300x10mm,2Ф20长1.0m钢筋作成勾状与钢板牢固焊接，并锚入支墩混凝土中。钢支架提升横梁共1根，I20a工字钢，长度为4m，提升横梁与立柱上钢板牢固焊接，立柱之间采用Ф108*5mm钢管做斜撑，用以保证顶部框架的整体稳定性。详见图1、图2。二、编制依据（1）《建筑地基基础设计规范》(GB50007-2002)（2）《建筑结构荷载规范》(GB50009-2001)（3）《钢结构设计规范》(GB50017-2003)（4）《建筑施工手册》第四册（5）合同文件及其他相关规范规程三、钢支架架设方案3.1材料准备单个钢支架所需材料见表3-1。2表3-1钢支架材料汇总表序号材料名称型号规格单位数量备注1卷扬机JK-3（3T）台12滑轮3T组13钢管Ф108*5mmm244工字钢I20am45钢板10mmM223.2安装过程（1）基础处理。本工程竖井位于三滩一、二级水位观测站，钢支架基础落在井口平台上，平台为岩石面，在钢支架施工时只需对岩面找平，对应钢支架每个立柱的位置浇筑500×500×500mm（长×宽×高）的墩，然后在混凝土墩内预埋与地面上钢支架立柱位置相同的预埋铁。地基的技术要求如下：a、地基承载力，应不小于80kPa；b、基础表面应平整，水平度偏差不大于3mm。（2）钢支架立柱及上部结构吊装。钢支架部件安装顺序：立柱→横梁→加设支撑→卷扬机和滑轮安装。安装时先预拼装，然后整体拉升就位，预拼装将钢支架结构各部件连接好。钢支架吊装技术要求：1）基础垫坐强度已经达到要求。2）吊装过程中有测量人员现场检查安装尺寸及垂直度。3）吊装过程中有质检员检查安装质量。4）架体安装的垂直偏差，最大不应超过架体高度的1.5‰；5）钢支架截面内两对角线长度公差不得超过最大边长的3‰；6）横梁接点截面错位不大于1.5mm；7）卷扬机应有产品标牌，标明额定起重量，最大提升速度、制造单位、产品编号及出厂日期。8）钢支架安装完成后使用之前应进行检验：a．金属结构有无开焊和明显变形；b．架体各节点连接螺栓是否紧固；3c．架体的安装精度是否符合要求；d．安全防护装置是否符合要求；e．信号及通讯装置的使用效果是否良好清晰；f．钢丝绳、滑轮组的固接情况；四、钢支架受力检算4.1横梁提升架的受力为集中荷载。竖井开挖采用0.4m3的装碴筒出渣，石渣容重为2.5t/m3,石渣重为0.4×2.5×10=10KN,装渣筒质量按200kg计算，渣筒重为2KN,故集中荷载取10+2=12KN。根据过去施工经验，可选用I20a工字钢作大梁。为保证提升架经济、受力合理，选用不同类型的工字钢做大梁，进行强度和稳定性验算。采用I20a、Q235工字钢做大梁，梁跨度最大为4m，荷载为12KN,考虑根据竖井提升要求用单横梁，为简化计算，工字钢梁自重不计，卷扬机荷载考虑1.1的动力系数，动载分项系数取1.4；故，荷载组合设计值为Q1=1.1×1.4×12=18.48KN。(1)结构计算采用力学求解器计算出：(2)横梁弯矩图(3)横梁梁剪力图4横梁对立柱的力最大为R2=9240N，最大弯矩为Mmax=18480N*m横梁内力验算σ=18.48×106/287000=64.39N/mm2横梁的计算强度小于215N/mm2，满足要求！Vmax=Fl3/48EI=18480×40003/（48×2.06×105×23700000）=5.05mm横梁的最大挠度小于4000/400，满足要求！（4）稳定性计算横梁受压翼缘侧向自由度长度最大值L=4m,与梁宽度的比值L2/b=4000/100=40＞16，必须进行整体稳定性计算。Mmax/ωx/Ψb=64.39/0.76=85f4.2立杆若采用Ф108*5mm钢管，最大高度为4米。截面特性值：A＝13.06cm2i＝3.68cm刚度验算：长细比7.10868.3/400/il﹤150，满足要求计算整体稳定性：对属a类，查表得57.02223/215/41.121006.1357.01024.9mmNfmmNAN5满足要求。五、卷扬机安装根据工程需要，选择JK-3（3T）卷扬机，卷扬机配制限位器，防止提升重物是冲顶，5.1卷扬机地锚施工根据现有地形及卷扬机尺寸，在卷扬机的四个角上打安4根Φ25锚杆，孔深2米，外露0.2m，后期锚杆与卷扬机底座焊接，卷扬机的正后方地锚，选择能牢固锚固的区域打安4根Φ32锚杆，间排距30cm×30cm，孔深2米，外露0.3m，方位垂直于施工面，锚杆注浆采用M25砂浆，锚杆施工完毕等强后用40cm×40cm，σ=15钢板，锚杆从钢板4个预开的孔插出，外露的锚杆进行对角搭接焊，焊接时应注意锚杆与钢板之间预留出3cm左右间隙，后期钢丝绳从间隙处穿出与地锚可靠连接。搭接焊长度为20cm地锚示意图5.2安装卷扬机及承载钢丝绳（1）卷扬机安装地点应平整。卷扬机与基础或底架的连接应牢固，并应符合使用说明书的规定。（2）卷扬机与载荷之间不应有可能发生危险或影响钢丝绳寿命的障碍物。（3）卷扬机应固定牢靠，严防倾覆和移动，受力时不得横向偏移。绑缚卷扬机底座的固定绳索应从两侧引出，以防底座受力后移动；然后和正后方地锚可靠连接。6（4）钢丝绳的绳端固接钢丝绳应选用与其直径相应的绳卡，采用绳卡固接时，绳卡数量与钢丝绳直径有关，见表5-1。工作绳卡数量不得少于3个，此外还应在尾端加一个安全绳卡。绳卡间距不小于钢丝绳直径的6倍，绳头距安全绳卡的距离不小于140mm，并用细钢丝捆扎。绳卡滑鞍放在钢丝绳工作时受力的一侧，U型螺栓扣在钢丝绳的尾端，不得正反交错设置绳卡，见下图。表5-1与钢丝绳直径匹配的绳卡数5.3钢丝绳受力计算卷扬机钢丝绳选用直径17mm，吊索钢丝绳选用直径18.5mm,公称抗拉强度为1550N/mm的6×19的钢丝绳做吊索。根据钢丝绳容许拉力计算公式[Fg]=a×Fg/K式中[Fg]—钢丝绳容许拉力（kN）Fg—钢丝绳的钢丝破断力总和（kN）查表直径17mm,Fg=167.5kN；直径18.5mm,Fg=199.5kN；a—换算系数，取a=0.85k-钢丝绳安全系数，取卷扬机钢丝绳k=6；取吊索钢丝绳k=8[Fg]卷=a×Fg/K=0.85×167.5/6=23.7k