主线桥梁承台基坑钢板桩支护设计计算书.docx

主线桥梁承台基坑钢板桩支护设计计算书1 .主线桥梁承台基坑支护布置方案根据本工程桥梁承台所处地质环境及施工特点：主线桥梁墩台基本上均位于滩涂及水塘内，其墩位处水位地质情况为九龙江北港河床底标高为-6.5m,潮水位为-1.6m4.5m,承台基底土质主要以淤泥质土为主,最深厚度达到7.2m。主线桥梁所有承台均采用拉森IV型钢板桩作为承台基坑支护，当基坑深度小于5m时不考虑设置钢板桩内支撑，基坑深度在5m-8m之间时将设置两层由136b工字钢作为钢板桩内支撑。承台基坑钢板桩支护范围按照承台四个边各扩大1.5m控制。钢板桩围堰插打时按照高出最高洪水位0.5r进行控制。本工程所采用拉森IV型钢板参数表根据对不同深度的承台基坑支护进行验算，本工程拉森IV型钢板桩选用长度分别为9m、12m、15m、18m,共计4种。本工程钢板桩数量表桥墩承台开挖承台尺寸基坑开挖基坑单根钢板梁号深度(m)(m)尺寸(m)周长钢板桩根名称(m)桩长度(m)数(根)南n大桥左主线桥0#2.6446.4m*18m9.4m*21m60.8091521#1.4096.5m*6.5m9.5m*9.5m38.009952#6.7696.5m*6.5m9.5m*9.5m38.0018953#3.7406.5m*6.5m9.5m*9.5m38.0012954#2.6956.5m*6.5m9.5m*9.5m38.009955#7.7346.5m*6.5m9.5m*9.5m38.0018956#5.8486.5m*6.5m9.5m*9.5m38.0015957#3.1916.5m*6.5m9.5m*9.5m38.0012958#2.1786.5m*6.5m9.5m*9.5m38.009959#3.1926.5m*6.5m9.5m*9.5m38.00129510#1.4656.5m*6.5m9.5m*9.5m38.0099511#2.6176.4m*18m9.4m*21m60.809152南11大桥左辅道桥0#2.3346.4m*17m9.4m*20m58.8091471#4.0896.5m*6.5m9.5m*9.5m38.0012952#2.9496.5m*6.5m9.5m*9.5m38.009953#3.4206.5m*6.5m9.5m*9.5m38.0012954#1.8756.5m*6.5m9.5m*9.5m38.009955#4.9146.5m*6.5m9.5m*9.5m38.0015956#7.5286.5m*6.5m9.5m*9.5m38.0018957#2.8716.5m*6.5m9.5m*9.5m38.009958#1.8586.5m*6.5m9.5m*9.5m38.009959#2.8726.5m*6.5m9.5m*9.5m38.0099510#1.6456.5m*6.5m9.5m*9.5m38.0099511#2.3076.4m*17m9.4m*20m58.809147南n大桥右主线桥0#2.3496.4m*17m9.4m*20m58.8091471#2.7796.5m*6.5m9.5m*9.5m38.009952#2.6396.5m*6.5m9.5m*9.5m38.009953#3.1106.5m*6.5m9.5m*9.5m38.0012954#2.5656.5m*6.5m9.5m*9.5m38.009955#3.1046.5m*6.5m9.5m*9.5m38.0012956#5.2186.5m*6.5m9.5m*9.5m38.0015957#1.5616.5m*6.5m9.5m*9.5m38.009958#2.0486.5m*6.5m9.5m*9.5m38.009959#2.5626.5m*6.5m9.5m*9.5m38.0099510#3.8596.5m*6.5m9.5m*9.5m38.00129511#2.3196.4m*17m9.4m*20m58.809147南11大桥右辅道桥0#2.1816.4m*18m9.4m*21m60.8091521#2.7896.5m*6.5m9.5m*9.5m38.009952#4.6496.5m*6.5m9.5m*9.5m38.0012953#2.8906.5m*6.5m9.5m*9.5m38.009954#3.5756.5m*6.5m9.5m*9.5m38.0012955#3.1146.5m*6.5m9.5m*9.5m38.0012956#3.2286.5m*6.5m9.5m*9.5m38.0012957#5.0716.5m*6.5m9.5m*9.5m38.0015958#4.0586.5m*6.5m9.5m*9.5m38.0012959#2.5726.5m*6.5m9.5m*9.5m38.0099510#3.8946.5m*6.5m9.5m*9.5m38.00129511#2.2326.4m*18m9.4m*21m60.809152南n0#3.64017.34m*6.4m20.34m*9.4m59.4812143村中桥左主线桥1#3.64O17.34m*6.4m20.34m*9.4m59.4812143南n村中桥右主线桥0#3.70021.09m*6.4m24.09m*9.4m66.98121621#3.70021.30m*6.4m24.3m*9.4m67.4012162南11村中桥左辅道桥0#3.64022.34m*6.4m25.34m*9.4m69.48121641#3.64022.34m*6.4m25.34m*9.4m69.4812164南n村中桥0#3.70018m*6.4m21m*9.4m60.80121521#3.70018m*6.4m21m*9.4m60.8012152角泰路中桥左幅主线桥0#2.37017.34m*6.4m20.34m*9.4m59.4891431#3.6076.5m*6.3m9.5m*9.3m37.6012942#3.3386.5m*6.3m9.5m*9.3m37.6012943#1.93717.34m*6.4m20.34m*9.4m59.489143角泰路中桥右0#2.37017.34m*6.4m20.34m*9.4m59.489143幅主线桥1#3.6076.5m*6.3m9.5m*9.3m37.6012942#3.3386.5m*6.3m9.5m*9.3m37.6012943#1.93717.34m*6.4m20.34m*9.4m59.489143角0#2.37018m*6.4m21m*9.4m60.809152泰路中桥左辅道桥1#3.6076.5m*6.3m9.5m*9.3m37.6012942#3.3386.5m*6.3m9.5m*9.3m37.6012943#1.93718m*6.4m21m*9.4m60.809152角0#2.37018m*6.4m21m*9.4m60.809152泰路中桥右辅道桥1#3.6076.5m*6.3m9.5m*9.3m37.6012942#3.3386.5m*6.3m9.5m*9.3m37.6012943#1.93718m*6.4m21m*9.4m60.809152杨厝中桥左幅主线桥0#0.79017.34m*6.4m20.34m*9.4m59.4891431#2.9676.5m*6.3m9.5m*9.3m37.609942#1.6406.5m*6.3m9.5m*9.3m37.609943#2.4276.5m*6.3m9.5m*9.3m37.609944#2.50017.34m*6.4m20.34m*9.4m59.489143杨0#0.79017.34m*6.20.34m*9.59.489143厝中桥右幅主线桥4m4m1#2.966.5m*6.3m9.5m*9.3m37.6099472#1.646.5m*6.3m9.5m*9.3m37.6099403#2.426.5m*6.3m9.5m*9.3m37.6099474#2.5017.34m*6.20.34m*9.59.48914304m4m杨厝中桥左辅道桥0#0.79018m*6.4m21m*9.4m60.8091521#2.966.5m*6.3m9.5m*9.3m37.6099472#1.64O6.5m*6.3m9.5m*9.3m37.609943#2.4276.5m*6.3m9.5m*9.3m37.609944#2.50018m*6.4m21m*9.4m60.809152杨厝中桥右辅道桥0#0.79018m*6.4m21m*9.4m60.8091521#2.9676.5m*6.3m9.5m*9.3m37.609942#1.6406.5m*6.3m9.5m*9.3m37.609943#2.4276.5m*6.3m9.5m*9.3m37.609944#2.50018m*6.4m21m*9.4m37.60994合计10420基坑开搀深度h<5m时的承台基坑支护平面布置图基坑开挖深度5mh<8m时的承台基坑支护平面布置图二基坑开挖深度5mh<8m时的承台基坑支护立面布置图2 .主线桥梁承台基坑钢板桩支护计算2.1. 基坑开搀深度h<5m时的承台基坑钢板桩支护计算（1阚南门大桥3#桥墩承台基坑支护为计算对象,基坑计算参数如下:H地面=2.055mH承台基坑底二-L485mh（基坑开挖）=3.74m（考虑超挖20cm（浇筑C20封底磴）承台开挖面积：9.5m×9.5m（2）r.（P按照12m范围内的加权平均值计算：各类土体计算参数（按照地表以下12m范围土体考虑）：淤泥质土:hl=3.83m,rl=26.7KN/m3、l=2.6xCl=10.35kpa;粉质粘性土夹细砂：h2=4.9m,r2=26.9KNr3x2=12.3C2=29.8kpa;砂土状强风化花岗闪长岩：h3=3.27m,r3=21KNm3x3=30oxC3=30kpa;r加权平均=(rl×hl+r2×h2+r3×h3)12=(26.7×3.83+26.9×4.9+21×3.27)12=25.2KNm3加权平均二(lhl+2h2+3h3)12二(2.613.83+12.3x4.9+30x3.27)/12=14.1°(3)钢板桩所承受的主动土压力计算Ka=tg2(45-2)=tg2(45-14.1o2)=0.608Kp=tg2(45+2)=tg2(45+14.1o2)=1.644Eah=rhKa=25.2KNm3X3.74mX0.608=57.3KNm2E叫二q挖掘机Ka=30KNm2×0.608Pb=Eah+Eaq=57.3KNm2+18.2KNm2=75.5KNm2yq=L5mtg(45+2)(挖掘机履带边缘距离承台基坑顶边缘按照1.5m考虑)=1.5m×tg(45+14.1o2)=1.923m(4)计算土压力强度为O处(桩墙前的被动土压力二桩墙后的主动土压力)距离开挖土层面的y值y=Pbr×(KKp-Ka)=75.5KNm225.2KNm3×(1.7×1.644-0.608)=1.37m(5)按简支梁计算等值梁的两支点反力(Ra和PO)WMC=OP0=0.5×3.74m×573KNm2×(2×3.743)+(3.74m-1.923m)×18.2KNm2×(3.74m-1.923m)2+1,923m+0.5×75.5KNm2×1.37m×(3.74m+1.37m3)(3.74m+1.37m)Q=oRa=0.5×3.74m×57.3KNr2+(3.74m-1.923m)×18.2KNm2+0.5×75.5KNm2×1.37m-113.08KN=78.9KN(6)计算钢板桩最小入土深度X=6P0r(KKp-Ka)0.5=6×113.08KN/252KNm3×(1.7×1.644-0.608)0.5=3.5mt=y+x=1.37m÷3.5m=4.87mt=l.lt=l.l×4.87m=5.357m钢板桩总长:L=3.74m+5.357m=9.097m,取12m。(7)钢板桩强度计算假设钢板桩所受最大弯矩处(剪力等于0处)距离钢板桩顶为XoRa-0.5X2rKa-(X-yq)qKa=078.9KN-0.5X2×25.2KNm3×0.608-(X-1.923)×30KNm2×7.66X2+18.24X-113.98=0X=2.846mMmax=RaX-O.5X3rKa3+(X-yq)2qKa2=78.9KN×2.846m-0.5×2.8463×25.2KNm3×0.6083+(2.846m-1.923m)2×30KNm2×0.6082=224.55-66.63=157.92kNm采用拉森IV型钢板桩，查该钢板桩产品性能表得：W=2072cm3mf=MmaxW=157.92kNmX10002072cm3m=76,2MPa<f=180MPa×1.5=270MPa,符合要求。2.2、 基坑开搀深度5mhV8m时的承台基坑钢板桩支护计算2.2.1, 基坑支护钢板桩无设置内支撑计算(1阚南门大桥6#桥墩承台基坑支护为计算对象,基坑计算参数如下:H地面=2.195mH承台基坑底二-3.453mh(基坑开挖)=5.848m(考虑超挖20cm(浇筑C20封底砂)承台开挖面积：9.5m×9.5m(2)r.(P按照工5m范围内的加权平均值计算：各类土体计算参数(按照地表以下15m范围土体考虑)：素填土:hl=2.518m,rl=18KNm3sl=15osCl=IOkpa;淤泥质土：h2=5.897mrr2=16.1KNm3x2=1.7oxC2=11.7kpa;细砂:h3=3.2mzr3=18.5KNm3x3=25oxC3=3kpa;粉质粘土:h4=1.8m,r4=19KN/m3、4=16.5o.C4=29.7kpa;细砂:h5=1.5m,r5=18.5KNm3x5=25C5=3kpa;全风化花岗闪长岩：h6=0.085mzr6=20KNm3x6=25oxC6=30kpa;r加权平均=z(rlhl+r2h2+r3h3+r4×h4+r5×h5+r6×h6)15=(18×2.518+16.1×5.897+18.5×3.2+19×1.8+18.5×1.5+20×0.085)/15=17.5KNm3(P力口权平均=(PIXhI+2×h2+3×h3+4×h4+5×h5+6×h6)15=(15×2.518+1.7×5.897+25×3.2+16.5×1.8+25×1.5+25×=13.(3)钢板桩所承受的主动土压力计算Ka=tg2(45-2)=tg2(45-13.1o2)=0.630Kp=tg2(45+2)=tg2(45+13.1o2)=1.586Eah=rhKa=17.5KNm3×5.848m×0.630=64.5KNm2E叫二q挖掘机Ka=30KNm2×0.630=18.9KNm2Pb=Eah+Eaq=64.5KNm2+18.9KNm2=83.4KNm2yq=1.5m×tg(45+2)(挖掘机履带边缘距离承台基坑顶边缘按照1.5m考虑)=1.5m×tg(45+13.1o2)=1.889m(4)计算土压力强度为O处(桩墙前的被动土压力二桩墙后的主动土压力)距离开挖土层面的y值y=Pbr×(KKp-Ka)=83.4KNm217.5KNm3×(1.7×1.586-0.630)=2.31m(5)按简支梁计算等值梁的两支点反力(Ra和PO)WMC=OP0=0.5×5.848m×64.5KNm2×(2×5.848/3)+(5.848m-1.889m)×18.9KNm2×(5.848m-1.889m)2+1,889m+0,5×83.4KNm2×2.31m×(5.848m+2.31m3)(5.848m+2.31m)=203.76KNQ=ORa=0.5×5.848m×64.5KNm2+(5.848m-1.889m)×18.9KNm2+0.5×83.4KNm2×2.31m-203.76KN=155.99KN(6)计算钢板桩最小入土深度X=6P0r(KKp-Ka)0.5=6×203.76KN/17.5KNm3×(1.7×1.586-0.630)0.5=5.81mt=y+x=2.31m÷5.81m=8.12mt=l.lt=l.l×8.12m=8.932m钢板桩总长:L=5.848m+8.932m=14.78m,取15m(7)钢板桩强度计算假设钢板桩所受最大弯矩处(剪力等于0处)距离钢板桩顶为XoRa-0.5X2rKa-(X-yq)qKa=0155.99KN-0.5X2×17.5KNm3×0.630-(X-1.889)×30KNm2×0.630=05.51X2+18.9X-191.69=0X=4.427mMmax=RaX-0.5X3rKa3+(X-yq)2qKa2=155.99KN×4.427m-0.5×4.4273×17.5KNm3×0.6303+(4.427m-1.889m)2×30KNm2×0.6302=690.57-220.3=470.27kNm采用拉森IV型钢板桩，查该钢板桩产品性能表得：W=2072cm3mf=MmaxW=470.27kNmX10002072cm3m=226.96MPa<f=180MPa×1.5=270MPa,符合要求。2.2.2,深基坑支护钢板桩设置内支撑计算（1阚南门大桥5#桥墩承台基坑支护为计算对象,基坑计算参数如下:H地面=L979mH承台基坑底二-5.555mh（基坑开挖）=7.734m（考虑超挖20cm（浇筑C20封底磅）承台开挖面积：9.5m×9.5m（2）深基坑支护方案钢板桩：采用拉森IV型钢板桩（L=18m根）围囹：采用136b工字钢内支撑：采用双层内支撑结构对基坑钢板桩内壁进行支撑，支撑材料采用136b工字钢及3258mm钢管，具体支撑方式：第一层内支撑（位于基坑顶部）只对四个角点进行斜支撑，支撑点设于距钢板桩内壁3.167m处；第二层内支撑（位于距离基坑顶部下方2.435m处），对四个角点进行斜支撑,支撑点设于距钢板桩内壁3.167m处,并对斜支撑之间的工字钢围囹设置单层十字3258mm钢管内支撑。深基坑底部处理：浇筑20cm厚C20封底混凝土。(3)r.按照工8m范围内的加权平均值计算：各类土体计算参数(按照地表以下18m范围土体考虑)：素填土:hl=2.518m,rl=18KNm3sl=15oxCl=IOkpa;淤泥质土：h2=5.897mrr2=16.1KNr3s2=1.7C2=11.7kpa;细砂:h3=3.2m,r3=18.5KNm3x3=25C3=3kpa;粉质粘土:h4=1.8mzr4=19KNm3x4=16.5o.C4=29.7kpa;细砂：h5=1.5m,r5=18.5KNm3x5=25C5=3kpa;全风化花岗闪长岩:h6=3.085mzr6=20KNm3.6=25C6=30kpa;r加权平均z=(rlhl+r2h2+r3h3+r4×h4+r5×h5+r6×h6)18=(18×2.518+16.1×5.897+18.5×3.2+19×1.8+18.5×1.5+20×3.085)/18(P力口权平均=(PlXhl+2×h2+3×h3+4×h4+5×h5+6×h6)15=(15×2.518+1.7×5.897+25×3.2+16.5×1.8+25×1.5+25×3.085)/18=15.1°(4)钢板桩承载力检算(取水文地质情况2进行计算)土压力恒载作用下：h=H=0.42X7.734m=3.248mM=lH3=0.18×7.7343=83.27KNmRl=0.32KNR2=H2=3.55×7.7342=212.34KN挖掘机活载(30KNm2)作用下：dh=m=0.3mlM=2H2=0.76×7.7342m=45.46KNmlRl=H=4.62×7.734m=35.73KNzlR2=H=12.62×7.734m=97.6KN土压力恒载与挖掘机活载（30KNm2）共同作用下：h（入土）=h+dh=3.248m+0.3m=3.548m,取4mI（钢板桩）=7.734m+4m=11.734m,取18moh（实际入土）=10.266mSl=0.567H-0.19h=0.567×7.734m-0.19×10.266m=2.435mS2=0.433H+0.19h=0.433×7.734m+0.19×10.266m=5.299mRl（总）=Rl+lRl=0.32KN+35.73KN=36.05KNR2（总）R2+R2=212.34KN+97.6KN=309.94KNM（总）=M+M=83.27KNm+45.46KNm=128.73KNmW（钢板桩）二M（总）o=128.73KNml03（180L5）=476.8cm3所采用的拉森IV型钢板桩，查该钢板桩产品性能表得：W=749cm3符合要求（5）136b工字钢围囹承载力检算第一层内支撑（位于基坑顶部）计算模型为悬臂简支梁Mmax=qlm22-qll28=36.05×3.16722-36.05×3.16728=135.59KNmVmax=qll2+qlm=36.05×3.1672÷36.05×3.167=171.26KN=MmaxW=135.59×1031139=119MPa<=145MPa符合要求=Vmax(H-2t2)×tl=171.26×103(360-2×16.5)×12.5=41.9MPa<=85MPa符合要求Wmax=qlm2l216EP5qll4384EI=36.05×31672×31672/(16×2.1×105×22781×104)-5×36.O5×31674/(384×2.1×105×22781×104)=4mm<1/400=8mm符合要求第二层内支撑(位于位于距离基坑顶部下方2.435m处)计算模型为两跨等跨连续梁Mmax=kmq2l2=0.125×309.94×1.5842=97.21KNmVmax=kvq2l=0.625×309.94×1.584=306.84KN=MmaxW=97.21×1031139=85.3MPa<=145MPa符合要求=Vmax(H-2t2)×tl=306.84×103(360-2×16.5)×12.5=75.1MPa<=85MPa符合要求Wmax=kwq2l4100EI=0.521×309.94×15844/(100×2.1×105×22781×104)=0.2mm<l400=4mm符合要求(6)325×8mm钢管内支撑承载力检算Nmax=(0.625+0.625)q2l=1.25×309.94×1.584=613.68KN3258mm钢管截面参数：A=D2×l-(d/D)24=×3252×l-(309/325)24=7963mm2i=D×l+(d/D)20.54=325mm×l+(309/325)20,54=112.1mml=8.78m=li=l×8.78×103112.1=78.3查钢结构设计手册中Q235钢b类截面中心受压直杆稳定系数值表得：=0.699=NmaxA=613.68×103/(0.699×7963)=110.3MPa<=145MPa符合要求(7)132a工字钢斜支撑承载力检算Nmax=250.45*1,415=354.4KN132a工字钢截面参数：A=67.156cm2i=12.8cml=4.24m=li=l×4.24×103128=33.125查钢结构设计手册中Q235钢a类截面中心受压直杆稳定系数值表得：=0.909=NmaxA=354.4×103(0.940×67.156×102)=56.1MPa<=145MPa（允许应力）材料符合要求