钢板桩围堰设计计算

PAGEPAGE3钢板桩围堰设计计算一、土层地质情况根据设计图纸提供的参数，设计洪水位为+5.40M，12#墩河床高程为-2.00M,土层地质为淤泥质粉质粘土，土性质为：为16.5KN/M3，φ取9.50，C取12.3KPa。二、支撑布置围堰中共设三道支撑，第一点支撑标高为+3.19M，第二支撑标高为+1.19M，第三道支撑标高为-2.41M,采用H40型钢进行支撑。以φ400的钢管进行斜支撑。支撑图纸如下图：支撑布置图（单位：M）三、体系简化验算：主动土压力系数：Ka=tg2(450-9.50/2)=0.717土压力：取浮=9N/M3Ea=1/2KaH22=1/2×0.717×9×5.6252=102.088KN/M水压力：纯水w水=1/2ρg(H1+H2)2=1/2×10×(7.4+5.625)2=848.253KN/M总压力：Ea+E水=102.088+848.253=950.341KN/M压力计算图（单位：M）四、应力计算R1=1/2×10×(5.4-3.19)2=24.42KN/MR2=1/2×10×(5.4+0.61)2-24.42=156.18-24.42=131.76KN/MR3=1/2×10×(5.4+5.018)2-156.18+1/2×0.717×(5.018-2)2×9=415.882KN/MR4=1/2×10×(5.4+7.625)2-542.674+1/2×0.717×9(7.625-2)2-29.388=378.284KN/M钢板桩验算采用拉森Ⅳ型，宽40cm，截面系数Wx=2270cm3R1=24.42×0.4=9.768KNR2=131.76×0.4=52.704KNR3=415.882×0.4=166.353KNR4=378.284×0.4=151.314KNN=1/2qH=1/2×0.4×9.8×H×H=1/2×3.92×H×H即q=3.92×HME=0MD=-1/2×10×(5.4-3.19)2×1/3×2.21×0.4=-7.196KN.MMC=9.768×2-1/6×10×4.213×0.4=-30.21KN.MMB=9.768×5.6+52.704×3.6-1/6×10×7.813×0.4-1/6×0.717×9(2.41-2)3×0.4=-73.18MA=9.768×10.815+52.704×8.815+166.353×5.215-1/6×10×0.4×13.0253-1/6×0.717×0.4×9(7.625-2)3=-111.942KN.MMDC中点=9.768×1-1/6×10×3.213×0.4=12.283KN.MMCB中点=9.768×3.8+52.704×1.8-1/6×10×6.013×0.4=54.9KN.MMBA中点=9.768×8.208+52.704×6.208+166.353×2.608-1/6×10×10.4183×0.4-1/6×0.717×9×3.0183×0.4=75.574KN.M根据计算结果绘制弯矩图如下：Max=111.942KN.M查表得钢板桩[σ]=180MPa截面模量w=2270cm3σ=111942/2270=49.3MPa<[σ]=180MPa满足要求！六、基坑底的安全验算按围堰施工至封底混凝土人顶标高-7.625根据公式>Kj取安全系数K=1.5土的浮容重=16.5-10=8.0KN/M3最大渗流力j=iwi=h/(h+2t)=(5.4+7.625)/(5.4+7.625+2t)=13.025/(13.025+2t)t为钢板桩底部到开挖面的距离所以j=iw=10×13.025/(13.025+2t)≥Kj≥1.5×130.25/(13.025+2t)t≥5.7Mt实施过程中取值为6.5M，大于5.7M，满足要求！根据上面计算设计的钢板桩围堰基坑底满足安全方面要求。支撑设置及安全验算：第一道支撑设置及计算：最大受力状态为围堰外水位为+5.4M，堰内抽水至第二道支承下50cm，即0.69M时，作为计算考虑。水压力w水=1/2×10×（5.4-0.69）2=110.92KN/Mw=110.92KN/MQA=QB=0.4ql即RA=RD=0.4×36.97×4=59.152KNRB=RC=(36.97×12-59.152×2)/2=162.668KNN直=RA+2RB=384.488KNN斜=2RB=325.336KN直撑验算：单根H40,Iy=22400iy=10.1截面积219.5cm2宽b=40M组合截面Jy=2[22400+21915×202]=220400cm4iy=22.4cmλ=ul/I=1×400/22.4=17.85查表得φ1=0.783k=1.4[kσ]=0.783×180=140.94MPa则σ=1.4×384.488×103/0.783×2×219.5×10-4=15.66MPa<[σ]=140.94MPa满足要求！斜支撑验算：φ1=0.635k=1.4采用50×50×1cm钢板σ=1.4×302.37×103/0.635×2×50×50×10-4=1.33MPa<[σ]，满足要求！弯矩验算：Mmax=-0.1×ql2=-0.1×36.97×42=59.152KN.Mσ=1.4Mmax/w=59.152×1.4×103/2×1073.349×10-6=38.58MPa<[σ]，满足要求！第二道支撑设置及计算：计算状况：水位5.4M堰内抽水到-2.91M以准备焊接第三道支撑R2=1/2×10×(5.4+0.86)2-1/2×10×(5.4-3.19)2=171.52KN/MQA=QB=0.4ql即RA=RD=0.4×51.17×4=91.484KNRB=RC=(91.48×12-2×171.52)×1/2=377.36KN直撑轴力：N直=RA+1.414RB=625.07MPaN斜=1.414RB=533.59MPa直撑验算：单根H40,Iy=22400iy=10.1截面积219.5cm2宽b=40M组合截面Jy=2[22400+21915×202]=220400cm4iy=22.4cmλ=ul/I=1×400/22.4=17.85查表取φ=0.783k取1.4[σk]=0.783×180=140.94MPaσ=KN/ΦAm=1.4×625.07×10-3/0.783×219.5×10-4=50.92MPa<[σ]，满足要求！斜撑验算：查表φ=0.635k取1.4采用50×50×1cm钢板σ=KN/φAm=