桥墩桩基础设计计算书..

1、基础工程课程设计一设计题目：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，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Y比例系数m推荐容许承载力“极限摩阻力T1淤泥质土4.6m软塑16kN/m标准荷载:(1) 恒载桥面自重：N=1500kN+8

2、x10kN=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) 活载跨活载反力：N5=2835.75kN，在顺桥向引起的弯矩：M厂3334.3kMf;两跨活载反力：N6=5030.04kN+8x100kN；(3) 水平力制动力：H厂300kN，对承台顶力矩6.5m;风力：H2=2.7kN对承台顶力矩4.75m主要材料6MN/m承台采用C30混凝土，重度Y=25kN/n3>y45kN/m3浮容重)，桩基采用C30混凝土，HRB335级钢筋；50kPa20kPa2粘土

3、3.8m灰黄色，硬塑17kN/m315MN/m4240kPa50kPa3碎石>50m黄色，密实20kN/m355MN/m4550kPa240kPa4、墩身、承台及桩的尺寸墩身采用C30混凝土，尺寸:长宽高=3仏6.5皿3。承台平面尺寸:长宽=7熔.5皿2,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Yo=1.1荷载组合系数年10,恒载分项系数Y=1.2活载分项系数Y=1.46、设计荷载（1）桩、承台尺寸与材料承台尺寸：7.0mx4.5mx2.5m初步拟定采用四根桩，设计

4、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）4.752.51K.N4恒载及二孔活载时:N1.2（1580540080097515074.52.515）+1.45830.04=19905.556KN桩（直径1m）自重每延米为:n12q=V1511.781KN/

5、m（已扣除浮力）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，般冲刷线以下深度为h2，则:It2mAaii00ky(h3)222桩的设计桩径lm，冲抓锥成孔直径为1.1m，桩周长和面积为U=nxl.l=3.456m,盲10.785n2,假定桩长20m取久=0.70t/d0.取m°=0.80查表得K2=6.0已知=550KPa2019905.556ql0.5qh405058.8565.891h土换算加权重度2164.6173.8(h24.63.8)20h2101029.

6、8h2NP1ulT2mA°ky(h3)0.53.456h2ii002224.6203.850(h24.63.8)2400.70.80.7855506(1029.hf)(h1)h12(441.096h21147.916h3829.416)令NhP得4h23h5舍去负值.)现取h=17m20m,满足取久=0.70,贝山桩低标高为1.00m2.单桩竖向允许承载力代入数据h=17m得h2P丄UT2mA°ky(h3)5480.67KN2ii0022229.829.8加权重度10二10二8.432KN/ma2h21723、桩的平面布置图25.00m常水位；70022.00m河床20.0

7、0m般冲刷线18.00m最大冲刷线n505000承台平面布置图1.00m桩底标高10.040010050100150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blbKKKd0.9(d1)k，沿水平力H作用方向上装间净距1f01b'LL1.5m0.6h0.63(d1)*3.6m，Kb'10.767m,b1.381m，110.6h11满足nb2.762B'14.5取一排装两边外侧边缘距离B'3.5m12)计算桩-土变形系数地面或最大冲刷线下的影响深度h2(d1)4m范围内有两层土。mmh2m(2hh)hm112120h2m62.61

8、5(22.61.4)1.4/4211197.5KN/m40.67E0.673107h2.°1107Kn/m2,Id4o.。49叽0.436mi,hh7.4122.5，满足按弹性桩计算3)桩顶刚度系数1、2、3、4的计算l20182m,h17m,0.5Ad20.785n204mh011197.5171.904105KN/m3,A042.54.91m2(按桩中心距计算)11Ihf-9AECAh0020.5170.7853107111.9041054.916.601050.670EI已知hh查表得：Q3EI27.4124),取用，l000.4839,50.6491,6MM0.040E1I,

9、2EIQ3M0.43620.872m1.253570.1234EI,EI4M0.5466EI(4)计算承台地面远点O处位移0、b0、单孔活载+恒载+制动力)N15713.555863.26b0n40.670EIEI1n4n2mx21mi140.5466EI0.67EI41.25240.0401EI0.1604EI,n36.3739EI40.1234EI0.4936EI,n20.2436(EI)2nx2HnM41i3i4nn24nMc2ix21ii1nH3n23mnnx2241ii1(n)236.3739EI423.780.4936EI8475.4250.1604EI6.3739EI0.0.24

10、36El)20.1604EI8475.4250.4936EI8475.4250.1604EI6.3739EI0.0.2436El)28840.31EI2014.24Ei(5)计算作用在每根桩顶上的作用力Pi、Qi、Mi竖向力pibx10i00.670EI5863.26El1.2叩5615.31KN2241.46KN水平力Qi弯矩Mi20400.0401EI8840.310.1234EI2014.24105.94KN30EIEI2014.248840.31-a0.5466EI0.1234EI10.09KNm30EIEI校核:nQ4105.94KN423.76KNH423.78KNii1ni1xp

11、iinpInM2(5615.312241.46)1.254i2(5615.312241.46)15713.54KN10.098474.985KNmMp15713.55KN,校核正确8475.425KNm(6)计算最大冲刷线处桩身弯矩M。，水平力Q0及轴向力P0MMQl10.09105.942221.97KNm0ii0QQ105.94KN,P5615.310.7852155641.86KN0i0(7)最大弯矩Mmax及最大弯矩位置Zmax的计算M0.436221.97C-0-0.9135QQ0105.94Z-0.97838查表得：ZZ0.97838,Z2.244mmax0.436可查表(线性内插

12、)得KM1.666MMK221.971.463369.80KNm0.436m1,h7.4124(取4)max0M(8)桩顶纵向水平位移验算桩在最大冲刷线处水平位移xo和转角(p。的计算查表得：Ax2.44066，Bx1.62100，A1.62100，BQM105.94221.97XoAoB2.44066O3EIx2EIx0.4363EI0.4362EI1.750581.621003.21103m3.21mm6mm，符合规范要求Q7EIEI105.94221.97(山问+亦(1-75058)1-82103rad桩顶纵向水平位移MeiB黑“盼需"75058）1-82103radQl3Ml

13、2m3-211°3（1-821°3）23EI2EI（6-850'31）103m7血水平位移容许值=0.525=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(并作已经算出b1.38m,11Z曲线，zMz/、zF曲线）221.97KNm0.436m1,Q105.94KN,M2M0b1ZX00ZZZAxBxZAbx12M0ZBbx1ZX002.440661.6210000.2293580.12.278731.450947.6216682314.43320207612.054870.4587160.22.117791.29088

14、14.166744437.88830950422.055050.9174310.41.802731.0006424.1183641212.2294218236.347791.3761470.61.502680.7498130.1560827813.7458168443.90191.8348620.81.22370.5372732.7432751213.1325980645.875872.29357810.970410.3611932.4573032711.0357992643.49313.4403671.50.466140.0628823.386476872.8818532826.268334

15、.58715620.146960.075729.830742244.627097765.2036445.9633032.6-0.039860.111363.4663132928.84648294412.31286.88073430.087410.094718.770806818.6813080217.45218.0275233.50.104950.0569812.285919286.0933842218.37939.17431240.107880.0148714.433049441.8173519216.25041曲线，ZXVZAx丁ZBx，2MZ”曲线，MzQ-AmM0Bm111xZZZAM

16、BMQAMMB0MMZ00010221.97221.970.2293580.10.09960.9997424.200808221.9122878246.11310.4587160.20.196960.9980647.8573408221.5393782269.39670.9174310.40.377390.9861791.6982222218.9001549310.59841.6055050.70.592280.93817143.9121944208.2455949352.15782.064220.90.689260.88407167.4763948196.2370179363.71342.5

17、229361.10.747140.8141181.5400772180.705777362.24593.2110091.40.764980.68694185.8748404152.4800718338.35493.6697251.60.737340.59373179.1588732131.7902481310.94915.0458722.20.53160.32025129.16816871.0858925200.25415.9633032.60.354580.1754686.155848438.9468562125.10276.88073430.193050.0759546.90728916.

18、858621563.76591&0275233.50.050810.0135412.34581383.005473815.351299.17431240.000050.000090.0121490.01997730.0321266、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M了369-80<Nm最大设计竖向力为P0.5qZ0.5UZ5641.860.50M-j66.3mm，又hh7.412(4)Nj11.7810.5，计算长度202.0820.5(23.4565580.718KN4页）5倔74.4故需要考虑纵向弯曲对偏心距的影响系数Mj6

19、6.ftm，又hNj1lh7.41(24)计算长度p4°.j65.5874.4e1400h0r500s0)2h10.950075.1mm,r0.22.71e0,1.150.01h20950mm，h1000mm，代入得：10.血,C30混凝土1RB钢筋Ra17.5Mp,Rgl-0h1而l05.5871.0841取1，0.364,2340MP，偏心距系数e0rr.1320.13222322.87,弯矩系数NrMj2958.4r3N轴力系数N一rr2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.

20、00222322.87367662958.44943.20.12880.9800.004383904943.20.13570.9600.006393045334.90.13030.9600.008409275334.9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Aur24712.39nm2现采用12_22,实配A'188424562mm2gg2）对截面进行强度校核实际Ar24562(5000.58%0.5%取a65mm其中rss层厚度C6522T54mm50mm，纵向钢筋间距91.9mmr435mmgs0.8混凝

21、土保护r80mm,满足要求，布置如下图所3)验算垂直于弯矩作用平面内承载力11.2N(fAfA')N(13.8103122801034562)s0uGcdhsdgu1.1413217.3KNN5580.718KN满足要求j7、承台设计（1）桩与承台的连接处构造设计承台平面尺寸：长宽=7熔.5皿2,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100cm35*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

22、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B。（2）桩顶局部受压验算桩顶局部受压时按右式计算PARj/式中P.承台内基桩承受计算轴向力，jcamjPN5580.718KN,jj1,A120.785mm2,桥梁C30混凝土Rj20.1MP,系数1.54c4amARj/cam10.78520.1103/1.5410245.78KNN5580.718KN,满足要求，可按构造配筋j(3)承台受冲切验算承台有效高度h0=250-20-4=276cm,跨比桩边冲切，相关参数见桩平面布置图B，计算冲0x0x502260.840.20x0.221

23、，1.995a0yh00.8425总0.111,计算冲切系数:2260y0.22.701，h25002000,0.9hp0y1.390MP，则2C30混凝土HRB钢筋取ft2.701(2.50.5)0.91390(ba)0xc0y(h0yc1.995(10.25)a)ox2.2459389.3KNC1C2150cma1x50cm,a25cm,计算冲切系数1y1x0.560.2fht05615.31KN满足要求0.56hp0.2210.21.3301y1.801，0.9Nj1x(c0.5a)(c0.5a)hpj1x21y1y11x0.913902.2414888.3KN5615.31KN满足要求(4)抗剪承载力验算fhhpt01.330(1.50.50.25)1.801(1.50.50.5)0.221