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/m36MN/m450kPa20kPa2粘土3.8m灰更色

2、，硬塑317kN/m315MN/m4240kPa50kPa3碎石>50m黄色，密实20kN/m355MN/m4550kPa240kPa2、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：N4=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：M1=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=

3、2.7kN,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乍o=1.1,荷载组合系数后1.0,恒载分项系数段=1.2,活载分项系数p=1.46、设计荷载(1) 桩、承台尺寸与材料承台尺寸：7.0mx4.5

4、mx2.5m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：N1.2(1580540080097515074.52.515)1.42835.7515713.55KNH1.4(3002.7)423.78KNM3334.3300(2.56.5)2.7(4.752.5)1.48475.425KN恒载及二孔活载时：N1.2(1580540080097515074.52.515)+1.45830.04=19905.556KN桩(直径

5、1m)自重每延米为：冗12一q=1511.781KN/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：NhlEi入m°A&k2丫2(h23)19905.556Nh4土换算加权重度1NhPU24.6203.8一一2986(1098)h250(h(h1)m0A(r0k2Y2(h23)0.53.4564.63.8)2400.70.80.7855501147.916h3829.416)桩的设计桩径1m,冲抓锥成孔直径为1.

6、1m,桩周长和面积为_12U=兀x1.1=3.456m,0.785m，假定桩长<20m取入=0.70t/d<0.3取mo=0.804查表得k2=6.0已知0=550KPaqIo0.5qh5058.8565.891h164.6173.8(h24.63.8)20_29.81010h2h2Nh435.205h26218.554h13947.1280h16.26m(舍去负值)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_1、P-Ul再入m0A5k2T2(h23)5480.67KN2加权重度2104至10工988.432

7、KN/m3h21723、桩的平面布置图25.00m常水位22.00mW床20.00mr-般冲刷线18.00mM大冲刷线052501.00m桩底标高10040010045050100300承台平面布置图5010a50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blbiKfK0Kd0.9(d1)k,Q沿水平力H作用方向上装间净距1b11.381m,1bLiL11.5m0.6h10.63(d1)3.6m,Kb10.767m,0.6h1满足nb12.762B114.5,取一排装两边外侧边缘距离B13.5m地面或最大冲刷线下的影响深度hm2(d1)4m范围内有两层土。0.

8、67Eh0.673107便。即次m0mh1m2(2hh2)h262.6计算桩-土变形系数15(22.61.4)1.442211197.5KN/mh24m_724_42.0110KN/m,Id0.0491m，64h7.4122.5,满足按弹性桩计算(3)桩顶刚度系数1、2、3、4的计算._一_.221020182m,h17m,0.5,A-d0.785m4Comoh11197.5175321.90410KN/m,Ao2.5424.91m2(按桩中心距计算)已知:h20.5170.7853107115_56.60100.670EI1.9041054.91查表得:AEhh7.4124,取用4,1l00

9、.43620.872mq0.48395m0.64916m1.25357EIM0.5466EI3_23EIQ0.0401EI,32EIM0.1234EI,4(4)计算承台地面远点O处位移0、b。、0(单孔活载+恒载+制动力),N15713.555863.26b0n140.670EIEIm2_2一n41Xm40.5466EI0.67EI41.256.3739EIi1n240.0401EI_22_20.1604EI,n340.1234EI0.4936EI,n30.2436(EI)in41XHn3Mi1a0i22n2n41xn3i16.3739EI423.780.4936EI8475.4258840.

10、310.1604EI6.3739EI0.0.2436(EI)2EIn2Mn3Hm22n2n41Xi(n3)i10.1604EI8475.4250.4936EI8475.4252014.24ZZ_2Z0.1604EI6.3739EI0.0.2436(EI)EI(5)计算作用在每根桩顶上的作用力Pi、Qi、Mi竖向力P1b00.670EI5863.26EI1.252014.24EI5615.31KN2241.46KN,一884031201424水平力Q20300.0401EI0.1234EI105.94KN2030EIEI2014.248840.31弯矩Mi403ao0.5466EI0.1234E

11、I10.09KNm14030EIEI校核：nQ4105.94KN423.76KNH423.78KNn8475.425KNmXRnMi2(5615.312241.46)1.25410.098474.985KNmMi1nRi12(5615.312241.46)15713.54KNP15713.55KN校核正确(6)计算最大冲刷线处桩身弯矩M0,水平力Q及轴向力P05615.310.7852155641.86KN叫MiQil010.09QQi105.94KN,P0105.942221.97KNm(7)最大弯矩Mmax及最大弯矩位置Zmax的计算0.436m1,h7.4124(取4)CQM00.436

12、221.97-0.9135Q。105.94查表得：ZZ0.97838,ZJmax0.978382.244m0.436可查表(线性内插)得KM1.666MmaxM0KM221.971.463369.80KNm(8)桩顶纵向水平位移验算桩在最大冲刷线处水平位移X。和转角()o的计算查表得：A2.44066,Bx1.62100,A1.62100,B1.75058、，Qo“Mo-105.94-221.97Xo3oA2Bx32.440662-1.62100EIEI0.436EI0.436EI一一一33.21103m3.21mm6mm,符合规范要求QoMo105.94/、221.973O2°AB

13、2(1.62100)+(1.75058)1.8210radEIEI0.436EI0.436EI桩顶纵向水平位移_QAO2eiaMoBEI100lo105.94221.97.2(1.62100+(0.436EI0.436EI33Ql33.2110(1.8210)20EI1.75058)1.82103radMl：3君(6.850.31)10m7.16mm水平位移容许值=0.5J25=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、Z:Z曲线）已经算出b1.381m,0.436m1,Q105.94KN,M）221.97KNm1ZZ曲线，ZX告

14、ZAx鲁ZBxZZZAxBxQlZAxb12M0ZBb1ZBxZX002.440661.6210000.2293580.12.278731.450947.62166823114.43320207612.0548710.4587160.22.117791.2908814.166744437.88830950422.0550510.9174310.41.802731.0006424.1183641212.2294218236.347791.3761470.61.502680.74981307458168443.901911.8348620.81.22370.5372732

15、.74327512113.1325980645.8758712.29357810.970410.3611932.4573032711.0357992643.49313.4403671.50.466140.0628823.3864768712.8818532826.2683314.58715620.14696-0.075729.83074224-4.627097765.20364415.9633032.6-0.03986-0.11136-3.466313292-8.846482944-12.31286.8807343-0.08741-0.09471-8.77080681-8.68130802-1

16、7.45218.0275233.5-0.10495-0.05698-12.285919281-6.09338422-18.379319.1743124-0.10788-0.01487-14.43304944-1.81735192-16.2504“Q2Mn-Q1z：Z®线，ZXZAZB<,2Mz:Z曲线，Mz9AmM°BmnnZZZAMBmQ0AAMM0BmMz00010221.97221.970.2293580.10.09960.9997424.200808221.9122878246.11310.4587160.20.196960.9980647.857340822

17、1.5393782269.39670.9174310.40.377390.9861791.6982222218.9001549310.59841.6055050.70.592280.93817143.9121944208.2455949352.15782.064220.90.689260.88407167.4763948196.2370179363.71342.5229361.10.747140.8141181.5400772180.705777362.24593.2110091.40.764980.68694185.8748404152.4800718338.35493.6697251.60

18、.737340.59373179.1588732131.7902481310.94915.0458722.20.53160.32025129.16816871.0858925200.25415.9633032.60.354580.1754686.155848438.9468562125.10276.88073430.193050.0759546.90728916.858621563.765918.0275233.50.050810.0135412.34581383.005473815.351299.17431240.000050.000090.0121490.01997730.0321266、

19、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Mj369.80KNm最大设计竖向力为NjP00.5qZ0.5UZMje066.3mm,又h0Nj5641.860.511.7810.5202.0823.4565580.718KNh7.412(4),计算长度lp0.5(240.4365.5874.4故需要考虑纵向弯曲对偏心距的影响系数e0，66.33又hh7.4124),计算长度lp0.5(2总藐)5.5874.41lelc一1(-)212,10.22.7e0,21.150.01-1,而l05.5871400曳hh0hh0h0rrs5000.9500950mm

20、h1000mni代入得：i0.364,21.0841取1,1.132e075.1mnu0.5m,C30昆凝土HRBffl筋R17.5Mp,Rg340MP,偏心距系数Ere00.132MjJ2958.43rN一一，轴力系数Nrj22322.872弯货!系数ENrr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NrNENrEN1.1320.13440.9800.00222322.87367662958.44943.20.12880.9800.004383904943.20.13570.9600.006393045334.90.13030.9600.008

21、409275334.9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Agur24712.39mm2现采用12_22，实配Ag188424562mm2(2)对截面进行强度校核As2r层厚度C6545620.58%0.5%M%65mmM中rs(500)2254mm50mm纵向钢肋间距91.9mm2435mmg区0.87昆凝土保护r80mml满足要求，布置如下图所示(3)验算垂直于弯矩作用平面内承载力2801034562)”,11.232s°NuG(fcdAhfsdAg)Nu(13.8103-121.1413217.3

22、KNNj5580.718KN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内上下两排并且不截断穿过桩身。箍筋设20箍_10,间距200mm,构造钢筋前后两端各18根_10,抗裂钢筋前后两端各8根_12下设相同的钢筋网具体配筋图见附图Bo(2)桩顶局部受压验算桩顶局部受压时按右式计算PjAcRa/m式中Fj承台

23、内基桩承受计算轴向力，PjNj5580.718KN,1,Ac-120.785mm实配钢筋Asy15282mm,保护层厚度7cm,沿x轴布置，具体配筋图件附图四、参考资料及应用软件1.公路桥涵设计通用规范JTGD60-2004;2.公路桥涵地基与基础设计规范JTGD63-2007;,桥梁C30昆凝土R220.1MP,系数m1.544AcR2/m10.78520.1103/1.5410245.78KNNj5580.718KN,满足要求，可按构造配筋(3)承台受冲切验算桩边冲切，相关参数见桩平面布置图B,计算冲承台有效高度h0=250-20-4=276cm,跨比0xa0xh00.84500.2212260yC30混凝土1.995C11.9950.2HRB钢筋取(10.25)0yfta0yh00.84252260.111，计算冲切系数:0y0.22.701,Qh25002000,取hp0.91.390MP,贝U20x(bca0y)0y(hcaox)hpfth02.701(2.50.5)0.91390C2150cma”50cm,a1y25cm,计算冲切系数hp0.9Nj1x(c20.913902.2414888.30.5a1y)1y