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时间:2018-08-09
《塔吊基础设计(四桩)》由会员上传分享,免费在线阅读,更多相关内容在行业资料-天天文库。
塔吊基础设计(四桩)计算书工程名称:海南工商职业学院22#教工住宅楼编制单位:江苏苏兴建筑工程有限公司1.计算参数(1)基本参数采用1台QZT80A(5613)塔式起重机,塔身尺寸1.80m,塔吊基础处开挖深度为-5.80m;现场地面标高-0.20m,承台面标高-4.60m。1)塔吊基础受力情况荷载工况基础荷载P(kN)M(kN.m)FkFhMMZ工作状态950.0030.001600.00340.00非工作状态850.0070.001800.000比较桩基础塔吊的工作状态和非工作状态的受力情况,塔吊基础按非工作状态计算如图;Fk=850.00kN,Fh=70.00kN,M=1800.00+70.00×1.22=1885.40kN.mFk,=850.00×1.35=1147.50kN,Fh,=70.00×1.35=94.50kN,Mk=(1800.00+70.00×1.22)×1.35=2545.29kN.m2)桩顶以下岩土力学资料序号地层名称厚度L(m)极限侧阻力标准值qsik(kPa)极限端阻力标准值qpk(kPa)qsiki(kN/m)抗拔系数λiλiqsik*i(kN/m)第8页,共8页 1中砂6.0050.00300.000.50150.002粉砂8.5035.00297.500.70208.253粉质粘土8.5070.001000.00595.000.70416.50桩长23.00∑qsik*Li1192.50∑λiqsik*Li774.753)基础设计主要参数基础桩采用4根φ400预应力管桩,桩顶标高-5.82m;桩混凝土等级C80,fC=35.90N/mm2,EC=3.80×104N/mm2;ft=2.22N/mm2,桩长23.00m,管道壁厚95mm;钢筋HRB335,fy=300.00N/mm2,Es=2.00×105N/mm2;承台尺寸长(a)=5.80m,宽(b)=5.80m,高(h)=1.32m;桩中心与承台中心2.20m,承台面标高-4.60m;承台混凝土等级C35,ft=1.57N/mm2,fC=16.70N/mm2,γ砼=25kN/m3。Gk=a×b×h×γ砼=5.80×5.80×1.32×25=1110.12kN塔吊基础尺寸示意图2.桩顶作用效应计算(1)竖向力1)轴心竖向力作用下第8页,共8页 Nk=(Fk+Gk)/n=(850.00+1110.12)/4=490.03kN2)偏心竖向力作用下按照Mx作用在对角线进行计算,Mx=Mk=1885.40kN.myi=2.20×20.5=3.11mNk=(Fk+Gk)/n±Mxyi/Σyi2=(850.00+1110.12)/4±(1885.40×3.11)/(2×3.112)=490.03±303.12Nkmax=793.15kN,Nkmax=186.91kN(基桩不承受竖向拉力)。(2)水平力Hik=Fh/n=70.00/4=17.50kN3.单桩允许承载力特征值计算管桩外径d=400mm=0.40m,内径d1=400-2×95=210mm=0.21m,hb=8.50hb/d=8.50/0.40=21.25,λp=0.80(1)单桩竖向极限承载力标准值计算Aj=π(d2-d12)/4=3.14×(0.402-0.212)/4=0.09m2,Apl=πd12/4=3.14×0.212/4=0.03m2Qsk=u∑qsiki=πd∑qsiki=3.14×0.40×1192.50=1497.78kNQpk=qpk(Aj+λpApl)=1000.00×(0.09+0.80×0.03)=114.00kNQuk=Qsk+Qpk=1497.78+114.00=1611.78kNRa=1/KQuk=1/2×1611.78=805.89kN(2)桩基竖向承载力计算1)轴心竖向力作用下Nk=490.03kN<Ra=805.89kN,竖向承载力满足要求。2)偏心竖向力作用下Nkmax=793.15kN<Ra=1.2×805.89=967.07kN,竖向承载力满足要求。4.桩基水平承载力验算(1)单桩水平承载力特征值计算I=π(d4-d14)/64=3.14/64×(0.404-0.214)=0.0012m4EI=EcI=3.80×107×0.0012=45600kN.m2查表得:m=2.00×103kN/m4,Xoa=0.010mbo=0.9(1.5d+0.5)=0.99m=990mmα=(mbo/ECI)0.2=(2.00×1000×0.99/45600)0.2=0.53αL=0.53×23.00=12.19>4,按αL=4,查表得:υx=2.441RHa=0.75×(α3EI/υx)χoa=0.75×(0.533×45600/2.441)×0.01=20.86kN(2)桩基水平承载力计算Hik=17.50kN<Rha=20.86kN,水平承载力满足要求。5.抗拔桩基承载力验算(1)抗拔极限承载力标准值计算Tgk=1/nu1ΣλiqsikLi=1/4×(2.20×2+0.40)×4×774.75=3718.80kN第8页,共8页 Tuk=ΣλiqsikuiLi=774.75×3.14×0.40=973.09kN(2)抗拔承载力计算Ggp=5.80×5.80×22.90×(18.80-10)/4=1694.78kNGp=0.09×23.00×(25-10)=31.05kNTgk/2+Ggp=3718.80/2+1694.78=3554.18kNTuk/2+Gp=973.09/2+31.05=517.60kN由于基桩不承受竖向拉力,故基桩呈整体性和非整体性破坏的抗拔承载力满足要求。6.抗倾覆验算a1=5.80/2=2.90m,bi=5.80/2+2.20=5.10m,倾覆力矩M倾=M+Fhh=1800+70.00×1.22=1885.40kN.m抗倾覆力矩M抗=(Fk+Gk)ai+2(Tuk/2+Gp)bi=(850.00+1110.12)×2.90+2×(973.09/2+31.05)×5.10=10963.82kN.mM抗/M倾=10963.82/1885.40=5.82抗倾覆验算5.82>1.6,满足要求。7.桩身承载力验算(1)正截面受压承载力计算按照Mx作用在对角线进行计算,Mx=Mk=2545.29kN.m,yi=2.20×20.5=3.11mNk=(Fk‘+1.2Gk)/n±Mxyi/Σyi2=(1147.50+1.2×1110.12)/4±(2545.29×3.11)/(2×3.112)=619.91±409.21第8页,共8页 Nkmax=1029.12kN,Nkmax=210.70kNΨc=0.85ΨcfcAj=0.85×35.90×1000×0.09=2746.35kN正截面受压承载力=2746.35kN>Nkmax=1029.12kN,满足要求。(2)预制桩插筋受拉承载力验算插筋采用HRB335,fy=300.00N/mm2,取622,As=6×380=2280mm2fyAs=300×2280=684000N=684.00kNfyAs=684.00kN>Nkmin=210.70kN,正截面受拉承载力满足要求。M倾/(4x1As)=1885.40×1000/(4×2.20×2280)=93.97N/mm2M倾/(4x1As)=93.97N/mm2<300.00N/mm2,满足要求。(3)承台受冲切承载力验算1)塔身边冲切承载力计算Fι=F-1.2ΣQik=Fk,=1147.50kN,ho=1.32-0.10=1.22m=1220mmβhp=1.0+(2000-1320)/(2000-800)×(0.9-1.0)=0.94а0=2.20-0.40/2-1.80/2=1.10m,λ=а0/ho=1.10/1.22=0.90β0=0.84/(λ+0.2)=0.84/(0.90+0.2)=0.76um=4×(1.80+1.22)=12.08mβhpβ0umftho=0.94×0.76×12.08×1.57×1000×1.22=16529.81kN承台受冲切承载力=16529.81kN>Ft=1147.50kN,满足要求。2)角桩向上冲切力承载力计算N1=Nk,=Fk,/n+Mxyi/Σyi2=1147.50/4+2545.29×3.11/(2×3.112)=696.09kNλ1x=λ1y=а0/ho=1.10/1.22=0.90,c1=c2=0.70+0.20=0.90mβ1x=β1y=0.56/(λ1x+0.2)=0.56/(0.90+0.2)=0.51[β1x(c2+а1y/2)+β1y(c1+а1x/2)]βhpftho=0.51×(0.90+1.10/2)×2×0.94×1.57×1000×1.22=2662.90kN角桩向上冲切承载力=2662.90kN>2Nl=1392.17kN,满足要求。3)承台受剪切承载力验算Nk,=Fk,/n+Mxyi/Σyi2=1147.50/4+2545.29×3.11/(2×3.112)=696.09kNV=2Nk,=2×696.09=1392.18kNβhs=(800/ho)1/4=(800/1220)0.25=0.90,λ=а0/ho=1.10/1.22=0.90α=1.75/(λ+1)=1.75/(0.90+1)=0.92,b0=5.80m=5800mmβhsαftb0ho=0.90×0.92×1.57×1000×5.80×1.22=9198.52kN承台受剪切承载力=9198.52kN>2Nl=1392kN,满足要求。(4)承台抗弯验算1)承台弯矩计算Ni=Fk,/n+Mxyi/Σyi2=1147.50/4+2545.29×3.11/(2×3.112)=696.09kN,Xi=1.30mM=ΣNiXi=2×696.09×1.30=1809.82kN.m2)承台配筋计算第8页,共8页 承台采用HRB335,fy=300.00N/mm2As=M/0.9fyho=1809.82×106/(0.9×300×1220)=5494mm2取2922@198mm(钢筋间距满足要求),As=29×380=11020mm2承台配筋面积11020mm2>7076mm2,满足要求。8.计算结果(1)基础桩4根φ400预应力管桩,桩顶标高-5.82m,桩长23.00m;桩混凝土等级C80,壁厚95mm,桩顶插筋422,(2)承台长(a)=5.80m,宽(b)=5.80m,高(h)=1.32m,桩中心与承台中心2.20m,承台面标高-4.60m;混凝土等级C35,承台底钢筋采用双向2922@198mm。(3)基础大样图塔吊基础平面图第8页,共8页 塔吊基础剖面图第8页,共8页 第8页,共8页
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