多排桩桩基设计计算

1、多排桩桩基设计计算姓名：班级：学号：指导老师：2017年1月3日目录一、设计资料1.(1)地质及水文资料1.(2)荷载2.(3)桩基础采用高桩承台式摩擦桩，根据施工条件，桩拟采用直径d=1.0m,以冲抓锥施工3二、计算3.(1)桩的计算宽度b13(2)桩的变形系数3.(3)桩顶刚度系数Ppp%HPMHPMM值计算3(4)计算承台底面原点O处位移30c000.4(5)计算作用在每根桩顶上作用力RQW5(6)计算局部冲刷线处桩身弯矩、水平力及轴向力M0Q0p0.5(7)局部冲刷线以下深度Z处桩截面的弯矩MZ及桩身最大弯矩M Mmax计算6.(8)局部冲刷线以下深度Z处横向土抗力巳计算7三、桩身配筋

2、计算及桩身材料截面强度验算9四、桩顶纵向水平位移计算1.2五、桩底持力层承载力验算1.2六、桩顶处的局部受压验算1.5一、设计资料（1 1）地质及水文资料河床土质为卵石，粒径为5060mm约占60%,2030mm约占30%,石质坚硬，孔隙大部分由砂密实填充，卵石层深度达58.6m。地基土水平向的抗力系数比例关系系数m=120000KN/m4（密实卵石）；地基土承载力基本容许值fa0=1000KPa；桩侧摩阻力标准值qk=400KPa;土的重度=20.00KN/m3（未计浮力）；土内摩擦角平=40。地面高程69.54m;一般冲刷线高程63.54m;局部冲刷线高程60.85m;承台底高程67.54

3、m;常水位高程69.80m。(2)(2)荷载上部为等跨30m的钢筋混凝土预应力桥梁，荷载为纵向控制设计，作用于混凝土桥墩承台底面中心纵桥向的荷载为：恒载加一孔活载：、N=8281KN、H=359KN、M-5025KNm恒载加两孔活载:口67.5467.54承台底局部冲刷蛾密实卵石层_横桥向断面横桥向断面飘桥向断面 2,02,0|1.0|1.0N阻8 80 0常空位DE立弘妈旷7763.5463.54一-诃渤刷、N-9288KN(3)(3)桩基础采用高桩承台式摩擦桩， 根据施工条件， 桩拟采用直径 d=1.0m,d=1.0m,以冲抓锥施工桩群布置经过初步设计算拟采用6根灌注桩，其排列见图1,位对

4、称竖直排列桩基础，经试算桩底高程拟采用50.54m。二、计算(1)(1)桩的计算宽度bl已知：kf=0.9m,d=1m,L1=1.5m,h1=3d1=6m,n=2也=0.61-b2L11-0.61.5cr-=0.60.7670.6h0.632b1=0.7670.92=1.38m(2)(2)桩的变形系数_72E=0.8Ec=0.82.5510KN/mc二d44二0.0491m641200001.38170.698m0.82.55100.0491桩在局部冲刷线以下深度h=10.31m,其计算长度则为:h=h=0.69810.31=7.202.5,故按弹性桩计算。k=b2mD4E：;m=120000

5、KN/m?-5(3)(3)桩顶刚度系数%*HHPMHPMM值计算1I0h1AEC0A0,4._.-.二d八八2l0=6.69m,h=10.31m,=0.5,A=0.785m4C0=mh=12000010.31=1.237106KN/m3/-,2Ad6匚,40)“cc2A0=兀一+htan=冗0.5+10.31父tan=16.88m244J222=S=2.5=4.91m44故取A=4.91m2。已知：h=ah=0.698x10.31=7.204,取用4。l0=：l0=0.6986.69=4.67查附表17、附表18、附表19得：7HH=:乍1%=0.0148EIXQ=0.0X4M360中，=M0

6、。.由公式得：PMH=G3EIXM=0.0684EI:MM=：3EI，=0.425EI(4)(4)计算承台底面原点 O O 处位移a。*。由公式得:N_82811245.64n：pp61.108EIEInn：MMPPXi2H-n?MHM7PpA07Pp6.690.510.31_0.7850.82.55107+i1.2371064.91口-1.11106-1.108EIa0=-、-n2n：HHIn：MM，PPX Xii1nnPMMPPxi2=60.425EI1.108EI61.252-12.94EIi1n7HH=60.0148EI=0.0888EI2_22n：MH=60.0684EI=0.410

7、4EI,n2：2MH=0.1684EI12.94EI3590.4104EI50256839.92-a020.0888EIX12.94EI-0.1684(EI)EI(5)(5)计算作用在每根桩顶上作用力pQiMi按公式计算，则竖向力、水平力、弯矩分别为:P-Pfc+xP广1108EI254.64十125M4871-2055.38KNp1Ppic0 xiH0)l.l08EI.-1.251704.95KN*IEIEIJ一一-6839.92487.52Qi=：HHa0一：HM-0=0.0148EI-0.0684EI=67.88KNEIEI校核:nQi=667.88：407.28kN、H=407.30k

8、Nn“Xi2PnMi=32055.38-704.951.256-260.65i1=3500.21KNm/M=3500.00KNmnnP=32055.38704.95=8280.99KN8281.00KNi1(6)(6)计算局部冲刷线处桩身弯矩、水平力及轴向力MOQOPOM0=MjQl0=260.6567.886.69-193.47KNmQo-67.88KNP0=2055.380.7856.6915-2134.15KNn：MHMn；MHHn nHHI In n；MM；PP二.xi2-2_n卜MH487.52EI=MMP 一MHa0=0.425EI487.52EI-0.0684EI6839.92E

9、I=-260.65KN求得M0Q0P0后就可以按单桩进行计算和验算， 然后进行群桩基础承载力和沉降验算。(7)(7)局部冲刷线以下深度 Z Z 处桩截面的弯矩M MZ及桩身最大弯矩M Mmax计算局部冲刷线以下深度Z处桩截面的弯矩MZ的计算Q067.88Mz=AMM0BM=AM193.47BM=97.25与193.47BM0.698无量纲系数AMBM由附表3、附表7分别查得，MZ计算列表如下表7-1:MZ计算列表表7-1Mz计算列表Z=c(zzAmBmQoAmOtMBmMz0.00.000.000001.000000.00193.47193.470.20.290.196960.9980619.

10、15193.09212.250.40.570.377390.9861736.70190.79227.500.60.860.529380.9586151.48185.46236.940.81.150.645610.9132462.79176.68239.471.01.430.723050.8508970.32164.62234.941.21.720.761830.7741574.09149.77223.861.42.010.764980.6869474.39132.90207.301.82.580.684880.4988966.6096.52163.122.23.150.531600.32025

11、51.7061.96113.662.63.720.354580.1754634.4833.9568.433.04.300.193050.0759518.7714.6933.473.55.010.000050.013540.002.622.62桩身最大弯矩Mmax及最大弯矩位置计算由CQ=1.99及h=4,查附表13得：ZMmax=0.889,故由ZMmax=0.889及h=4,查13附表得:KM=1.423。Mmax=KMM0=1.423193.47=275.308KNmmax0(8)(8)局部冲刷线以下深度 Z Z 处横向土抗力 J 计算=34.33ZA68.30ZBx由QZ=0得CQ二Mo

12、0.698193.47Qo67.88=1.99Mmax0.889=1.273mZAxZBx0.69867.88-iviv1.3820.6982193.47ZB1.38无量纲系数AxB由附表1、附表5分别查得，Pzx计算列表如表8-1:Pzx计算列表表8-1Z=uzzABxaQ0-0ZAxbi2M0ZBZBb1FZx0.00.002.440661.621000.000.000.000.20.292.117791.2908814.5417.6332.180.40.571.802731.0006424.7627.3452.100.60.861.502680.7498130.9630.7361.680

13、.81.151.223700.5372733.6129.3662.971.01.430.970410.3611933.3224.6757.991.21.720.745880.2190830.7317.9648.691.42.010.551750.1079326.5210.3236.841.82.580.25386-0.0357215.69-4.3911.302.23.150.06461-0.099404.88-14.94-10.062.63.72-0.0398-0.11136-3.56-19.78-23.33863.04.30-0.08741-0.09471-9.00-19.41-28.413.55.01-0.10495-0.05698-12.61-13.62-26.23三、桩身配筋计算及桩身材料截面强度验算由上可知，最大弯矩发生在局部冲刷线以下在Z=1.273m处，该处Mj=275.308KNmo计算轴向力Nj时，根据公路桥涵设计通用规范第4.1.6条知， 恒载分项系数取1.2,汽车荷载分项系数取1.4,人