桥墩桩基础设计计算书

1、基础工程课程设计设计题目:某桥桥墩桩基础设计计算二.设计资料：某桥梁上部构造采用预应力箱梁。标准跨径30m,梁长29.9m,计算跨径29.5m,桥面宽13m(10+2X1.5),墩上纵向设两排支座，一排固定，一排滑动，下部结构为桩柱式桥墩和钻孔灌注桩基础。1、水文地质条件：河面常水位标高25.000m,河床标高为22.000m,一般冲刷线标高20.000m,最大冲刷线标高18.000m处，一般冲刷线以下的地质情况如下：(1)地质情况c(城轨)：序号名称层厚土层描述天然重度丫比例系数m推荐容许承d极限摩阻力T1淤泥质土4.6m软塑16kN/m346MN/m50kPa20kPa2粘土3.8m灰更色

2、，硬塑317kN/m415MN/m240kPa50kPa3碎石>50m黄色，密实320kN/m455MN/m550kPa240kPa2、标准荷载：(1)恒载桥面自重：N1=1500kN+8X10kN=1580KN;箱梁自重：N2=5000kN+8X50Kn=5400KN;墩帽自重：N3=800kN;桥墩自重：M=975kN;扣除浮重：10*2*3*2.5=150KN(2)活载一跨活载反力：N5=2835.75kN,在顺桥向引起的弯矩：M=3334.3kNm-；两跨活载反力：N6=5030.04kN+8100kN;(3)水平力制动力：H=300kN,对承台顶力矩6.5m；风力：H2=2.7

3、kN,对承台顶力矩4.75m3、主要材料承台采用C30混凝土，重度丫=25kN/nf、丫='15kN/m3(浮容重)，桩基采用C30混凝土，HRB335级钢筋；4、墩身、承台及桩的尺寸墩身采用C30混凝土，尺寸：长嚏涓=3X2X6.5m3。承台平面尺寸：长侬=7X4.5m2,厚度初定2.5m,承台底标高20.000m。拟采用4根钻孔灌注桩，设计直径1.0m,成孔直径1.1m,设计要求桩底沉渣厚度小于300mm。5、其它参数结构重要性系数却=1.1,荷载组合系数后1.0,恒载分项系数2=1.2,活载分项系数旭=1.46、设计荷载(1) 桩、承台尺寸与材料承台尺寸：7.0mx4.5mx2.

4、5m初步拟定采用四根桩，设计直径1m,成孔直径1.1m。桩身及承台混凝土用30号，其受压弹性模量Eh=3x104MPa。(2) 荷载情况上部为等跨30m的预应力箱梁桥，混凝土桥墩，作用在承台底面中心的荷载为：恒载及一孔活载时：%N=1.2(15805400800975-15074.52.515)1.42835.75=15713.55KN%H=1.4(3002.7)=423.78KN£M=3334.为3冷0(2.5坨.5)2.7+)4.752.韦KM恒载及二孔活载时：vN=1.2(15805400800975-15074.52.515)+1.45830.04=19905.556KN桩(

5、直径1m)自重每延米为：冗12q=M15=11.781KN/m(已扣除浮力)4三、计算1、根据公路桥涵地基与基础设计规范反算桩长根据公路桥涵地基与基础设计规范中确定单桩容许承载力的经验公式，初步反算桩的长度，设该桩埋入最大冲刷线以下深度为h,一般冲刷线以下深度为h2,则：心=0=人£i.+入m0A40"2T2S2-3)2桩的设计桩径1m,冲抓锥成孔直径为1.1m,桩周长和面积为二12U=兀x1.1=3.456m,=0.785m，假定桩长<20m取入=0.70t/d<0.3取mo=0.80419905.556Nh二土换算加权重度2查表得K2=6.0已知k0】=55

6、0KPaIo0.5qh=5058.8565.891h16x4.6+17x3.8+(h+24.63.8)父20_29.810=10-,1'Nh=P=U£lm十入m0AL0I+k2y2(h2-3)=0.5父3.45624.6203.850(h2-4.6-3.8)2400.70.80.785550298126(10-)(h-1)(441.096h2-1147.916h-3829.416)h2h2令Nh=IP得：4h2-30舍去负值)=h2现取h=17m<20m,满足取入=0.70,则，桩低标高为1.00m2.单桩竖向允许承载力代入数据h=17m得IP】=1U£lir

7、i+Xm0AlL0】+k2T2(h23)=5480.67KN2一、298298,加权重度2=10-一二10-一=8.432KN/m3h21723、桩的平面布置图25.00m常水位22.00m可床7000521.00m桩底标高10040010050100150300承台平面布置图承台横桥向立面图承台纵桥向立面图4、桩的内力及位移计算(1)确定桩的计算宽度blb1=KfK0Kd=0.9(d+1)，k,'：沿水平力H作用方向上装间净距1，1bL一L1=1.5m;0.6h1=0.63(d1)=3.6m,.K=b'=0.767m,=b1=1.381m,1 10.6h11满足nb1=2.7

8、62:二B'1=4.5,取一排装两边外侧边缘距离B'=3.5m2 2)计算桩-土变形系数地面或最大冲刷线下的影响深度hm=2(d+1)=4m范围内有两层土。4=11197.5KN/m4mh；m2(2hh2)h262.6215(22.61.4)1.m0二二hm772'-T44E=0.67Eh=0.67父3M107=2.01M107KN/m2,I=-64=0.0491m4,64，汽=q/mt=0.436m',h=sh=7.412>2.5,满足按弹性桩计算:EI(3)桩顶刚度系数P1、P2、P3、P4的计算22l0=20-18=2m,h=17m,；=0.5,A=

9、d2=0.785m24C0=m0h=11197.517=1.904m105KN/m3,A0=±父2.52=4.91m2(按桩中心距计算)4120517115.-1=7=6.60105=0.670EIl°h10.78531071.9041054.91AEh*已知:h=：h=7.4124),取用4,l0=0.4362=0.872n查表得：q=0.48395m=0.64916m=1.253572=3EIq=0.0401EI,：3=12EIM=0.1234EI,：4=EIM=0.5466EI(4)计算承台地面远点b。O处位移口0、b。、口0(单孔活载+恒载+制动力)15713.55

10、_5863.2640.670EI-EIm.22n：4Xm=40.5466EI0.67EI41.25-6.3739EIi工n：2=40.0401EI=0.1604EI,n%=40.1234EI=0.4936EI,n2J2=0.2436(EI)2-J2一n411%XHn13Miai2n：2nz.Xii1-2一n：3_6.3739EI423.780.4936EI8475.425_8840.31-Z-_2一Z0.1604EI6.3739EI-0.0.2436(EI)EIn;?2MnP3Hn%n：4:八x2-(n7)i10.1604EI8475.4250.4936EI8475.4252014.240.1

11、604EI6.3739EI-0.0.2436(EI)2-EI(5)计算作用在每根桩顶上的作用力Pi、Qi、Mi5863.262014.24竖向力P=：1b0x-0)=0.670EI百一1.25百一5615.31KN二2241.46KN.一.884031201424水平力Q=自0(0转为=0.0401EIM.-0.1234EI.=105.94KN弯矩Mi=Dj0一：3a0=0.5466EIEIEI2014.248840.310.1234EI=10.09KNmEIEI校核：nQ=4105.94KN=423.76KN:八H=423.78KNn“xPnMi=2(5615.31-2241.46)1.25

12、410.09=8474.985KNm八M=8475.425KNmi土n£np=2x(5615.31+2241.46)=15713.54KN为£P=15713.55KN校核正确i土(6)计算最大冲刷线处桩身弯矩M0,水平力Q及轴向力P0=MiQil0=10.09105.942=221.97KNQ0=Qi=105.94KN,P0=5615.310.785215=5641.86KN最大弯矩Mmax及最大弯矩位置Zmax的计算=0.436m-.1查表得:M0Q。，二h0.436=7.412>4(取4)221.97105.940.9135可查表(线性内插)得Mmax=M0KM=

13、0.97838,0.97838max0.4362.244m=1.666221.971.463=369.80KNm(8)桩顶纵向水平位移验算Bq：、尸T.75058桩在最大冲刷线处水平位移X。和转角4。的计算查表得：A=2.44066,Bx=1.6210。A=-1.62100,Xo二藉入片民105.940.4363EI221.972.440662一1.621000.4362EI=3.2110m=3.21mm：6mm,符合规范要求O=4A.：区B.：=二EI二EI105.940.4362EI,221.973父(-1.62100)+-工(-1.75058)=-1.82父10rad0.436EI桩顶纵

14、向水平位移QAMo105.94221.973%=A+-B=工乂(-1.62100+乂(1.75058)-1.8210rad:2EI:EI0.436EI0.436EI33Ql3Mln31=。-010QM=3.2110-(-1.8210)200=(6.850.31)10m=7.16mm3EI2日水平位移容许值=0.5十25=2.5cm=25mm符合规范要求。5、按m法计算桩身入土段任一深度处的弯矩和桩侧横向土抗力(并作MZ|_Z、仃Z|_Z曲线)已经算出b=1.381m,：=0.436m,Q=105.94KN,=221.97KNm2QM-(1声ZZ曲线，仃ZX=-2Ax+0、ZBxb14Z0ZAx

15、Bx”Z，Axb12«M07.B71Bxb1CT7X002.440661.6210000.2293580.12.278731.450947.62166823114.43320207612.0548710.4587160.22.117791.2908814.166744437.88830950422.0550510.9174310.41.802731.0006424.1183641212.2294218236.347791.3761470.61.502680.74981307458168443.9019:1.8348620.81.22370.5372732.7

16、4327512113.1325980645.8758712.29357810.970410.3611932.4573032711.0357992643.49313.4403671.50.466140.0628823.3864768712.8818532826.2683314.58715620.14696-0.075729.83074224-4.627097765.20364415.9633032.6-0.03986-0.11136-3.466313292-8.846482944-12.31286.8807343-0.08741-0.09471-8.77080681-8.68130802-17.

17、45218.0275233.5-0.10495-0.05698-12.285919281-6.09338422-18.379319.1743124-0.10788-0.01487-14.43304944-1.81735192-16.2504_2._2na_(1冷加线，。ZX=¥ZZ&(2)MzZ曲线，Mz=3A+M0SnnaZZ=«ZAMBm屋AAMOfM0BmMz00010221.97221.970.2293580.10.09960.9997424.200808221.9122878246.11310.4587160.20.196960.9980647.85734

18、08221.5393782269.39670.9174310.40.377390.9861791.6982222218.9001549310.59841.6055050.70.592280.93817143.9121944208.2455949352.15782.064220.90.689260.88407167.4763948196.2370179363.71342.5229361.10.747140.8141181.5400772180.705777362.24593.2110091.40.764980.68694185.8748404152.4800718338.35493.669725

19、1.60.737340.59373179.1588732131.7902481310.94915.0458722.20.53160.32025129.16816871.0858925200.25415.9633032.60.354580.1754686.155848438.9468562125.10276.88073430.193050.0759546.90728916.858621563.765918.0275233.50.050810.0135412.34581383.005473815.351299.17431240.000050.000090.0121490.01997730.0321

20、266、桩身界面配筋计算(1)配筋的计算最大弯矩发生在Z=2.082m处，此处设计最大弯矩为Mj=369.80KN，m最大设计竖向力为Nj=P00.5qZ-0.5UZ=5641.860.511.781-0.5202.0823.456=5580.718KNMi4e0=66.3mm,又h=ah=7.412(>4),计算长度L=0.5(2+=5.587>4.4Njp0.436故需要考虑纵向弯曲对偏心距的影响系数7=件=66.而3又h=o(h=7.412>4),计算长度lp=0.5(2+/)=5.587>4.41lelc一=1(与2；1；2,1=0.22.7e0,；2=1.15

21、-0.01工_1,而l0=5.5871400曳hhehh0ho=r+rs=500+0.9M500=950mmh=1000TiE代入得：鸟=0.364,7=1.0841取1,J=1.132e“e0=75.1mnu=0.5m,C30昆凝土HRBffl筋R=17.5Mp,R=340MP,偏心距系数Er=-e0=0.132rN-,Mi轴力系数Nr=T=22322.872弯矩系数ENr=得=2958.4rr若取g=0.9,查墩台与基础附表得以下表格数据实际偏心系数E-2表中偏心系数E相应E配筋率NrNENrEN1.1320.13440.9800.00222322.87367662958.44943.20

22、.12880.9800.004383904943.20.13570.9600.006393045334.90.13030.9600.008409275334.9当u=0.006和u=0.008时均有N>Nr,EN>ENr,故桩身只需要按构造配筋，取u=0.006纵筋=unr2=4712.39mm2现采用12222,实酉己A；=1884黑2=4562mm2(2)对截面进行强度校核4562As4562r2=0.58%0.5%Mas=65mmM中rs=435mmg=0.87昆豌土保护二(500)r22层厚度C=65-=54mm>50mm纵向钢肋间距91.9mm>80mm,才两

23、足要求，布置如下图所小2铜筋布置示意图(尺寸中佗:m)(3)验算垂直于弯矩作用平面内承载力,-,11.232二s0NuMZlfcdAh+fsdAg)=Nu=(13.8M10M1+280M10父4562)1.14=13217.3KN>Nj=5580.718KN满足要求7、承台设计(1)桩与承台的连接处构造设计承台平面尺寸：长侬=7X4.5m2,厚度2.5m,承台底标高20.000m。采用桩顶主筋伸入承台连接。桩身嵌入承台内的深度为200mm；伸入承台内的桩顶主筋做成喇叭状，夹角15度。伸入承台内的主筋竖向高度为100cm>35*2.2=77cm,不设弯钩的带肋钢筋。抗弯钢筋布置在承台

24、内上下两排并且不截断穿过桩身。箍筋设20箍段10,间距200mm,构造钢筋前后两端各18根位10,抗裂钢筋前后两端各8根企12下设相同的钢筋网具体配筋图见附图B。(2)桩顶局部受压验算桩顶局部受压时按右式计算Pj<PAcRj/¥m式中Pj承台内基桩承受计算轴向力,Pj=Nj=5580.718KN,B>1,Ac=112=0.785mm2,桥梁C30混凝土R=20.1MP,系数Vm=1.544,PAcR；/?m>1父0.785M20.1父103/1.54=10245.78KN>Nj=5580.718KN,满足要求，可按构造配筋(3)承台受冲切验算承台有效高度h0=

25、250-20-4=276cm,桩边冲切，相关参数见桩平面布置图B,计算冲跨比/0xh050=0.221,226a0yh00.840x0.2=1.995-0y0.840.225226=0.111，计算冲切系数:=2.701，':h=2500>2000,取Php=0.9C30混凝土HRB钢筋取ft=1.390MP,则2Rg+a°y)+鼠(+a0x)息fh。=2.995M(1+0.25)+2.701M(2.5+0.5)卜0.9M1390M2.24=59389.3KN>5615.31KN满足要求0.560.56C1=C2=150cma1x=50cm,a1y=25cm,计算冲切系数氏=1.330,氏=1.801,1'x0.20.2210.2y取:p=0.9.Nj=二x(c20.5a1y)一：1y(c1-0.5a1x)jj:hpfth0=1.330(1.50.50.25)1.801(1.50.50.5)M0.9M1390X2.24=14888.3KN>5615.31KN满足要求(4)抗剪承载力验算1九=0.221,%=0.111,