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华中科技大学土木工程与力学学院《基础工程设计原理》课程设计任务及指导书(土木工程专业)姓名:学号:班级:二O一四年四月题目.柱下钢筋混凝土桩基础设计一、设计资料1.场地工程地质资料:见图1和表10.000-18.500-7.800-1.300杂填土灰色淤泥质土灰黄色粘性土图1.场地土层分布灰黑色淤泥质土-2.600表1各层土的物理性质及力学指标土层名称含水量w(%)重度γ(kN/m3)比重ds液限wL(%)塑限wP(%)内聚力c(kPa)内摩擦角φ(度)压缩模量ES1-2(MPa)承载力fak(kPa)杂填土16.0灰色淤泥质土38.218.52.7338.218.41053.5460灰黄色粘性土6.719.62.7132.717.718207.0220黑色淤泥质土30.118.92.7342.018.912144.651002.柱端传至承台顶面处的荷载(设计值)为:轴力F=5600(kN),弯矩M=500(kN-m),剪力V=140(kN)3.柱底面标高:-0.5m4.柱截面:2450600mm5.桩基安全等级:二级二、设计计算内容1.桩基础的类型及平面布置选用灌注桩,干作业成孔,桩径0.6m,初选承台埋置深度:1.5m桩穿入灰黄色粘性土深度:lC=2.7m≧2.5d,则桩的有效长度l=9.0m2.单桩承载力设计值按照规范经验公式法,查建筑桩基础技术规范(JGJ94-2008),桩的极限侧阻力标准值qsik(kPa)为:杂填土取24kPa;灰色淤泥质土取24kPa;灰黄色粘性土取94kPa;干作业挖孔灌注桩极限端阻力标准值qpk(kPa)取2700kPa;kNlquAqisikpppk6.15283.7643.764)947.2243.6(6.0416.02700QQQ2skpkuk则单桩的竖向承载力特征值为(安全系数K=2):kNKQuka3.76426.1528R3.确定装数和布置桩位偏心受压的桩基:1.11.19.84.76356001.11.1取,取eGaeGRFn暂取桩数为9,并采用三排布置柱距取中心距:Sa=2.0m承台厚取1.0m,桩边缘距承台边200mm承台平面尺寸为5.0×5.0mm2(d=1.0m):4.桩基础验算(按实体深基础模型)1).桩基竖向承载力验算中心荷载作用下:kNnGFkNi7.73495.661295.10125600N5.10125.1200.50.51.35G偏心荷载作用下:kNxxMyyMnGFiyix4.6810.7880.260.26407.734NmkN4061.0140005M22max2maxminmax所以:载力满足要求。综上所述:桩的竖向承03.6812.10.788NminmaxkNNRkNa2).水平荷载作用下,由于:1015600140竖向荷载水平荷载因此不考虑水平承载力的验算。3).桩尖平面处地基承载力验算取如图实体深基础模型:395.105.107.26.92.55.83.15.183.116mkNmkNldbamccf4.287495.105.100.50.5)(G所以:kPabaqlbaGGFpccsikiccf5.550.50.54051024.28745.6612)(2kPaWMppX1.650.50.5125005.553maxkPap9.45min承载力按深度和宽度修正:查表可得b=0.3,d=1.6kpaldbffmdbka96.4002.17576.5220)5.05.10(95.106.1)30.5(6.93.0220)5.0()3(所以:09.452.11.6596.4005.55minmaxkPapfkPapkPafkPapaa综上所述,桩尖持力层承载力满足要求4).桩尖平面处软弱下卧层承载力验算设计条件为s6d的群桩基础,取实体深基础模型,如图:a0=4.6m,b0=4.6m求基底附加应力:msikifcldbaqlbaGGFpp)()(200000取:mfldba)(G00得:06.46.44052.92-6612.5)(200000baqlbaGFppsikic综上所述,软弱下卧层承载力满足要求。5).桩基沉降验算⑴.求基底附加压力p0k不考虑扩散作用的方法,易知基底附加应力00kp。按考虑扩散作用的方法,用如图模型计算:取54/20mfkkkokldlblaGGFp)()tan2)(tan2(00‘近似取kNldbaGmoofk9.243295.105.106.46.4)(‘,则:kPaldlblaGGFpmfkkkok3.7795.105.105tan924.69.43221.355.6612)()tan2)(tan2(2000)(‘所以:kPapok3.77⑵.桩基沉降验算------桩顶沉降0S①.桩端平面处的计算沉降量---分层总和法取分层厚度mh0.1;利用角点法确定附加应力,将桩端分为四个正方形。1.32)tan2(0labl,沉降计算结果如下。沉降计算表)(mmzbl/bz/iiiz11iiiizz)(kPaEsimmSi010.000.25000.000.0070000.00100010.320.2483248.28248.28700010.97200010.650.2404480.75232.47700010.27300010.970.2266679.83199.0870008.79400011.290.2101840.52160.6970007.10500011.610.1934967.03126.5170005.59600011.940.17741064.5297.5070004.31700012.260.16351144.2979.7770003.52800012.580.15111208.4064.1170002.83900012.900.14011260.9052.5046503.491000013.230.13021301.9041.0046502.731100013.550.12181339.5337.6246502.501200013.870.11431371.1231.6046502.101300014.190.10751397.5726.4546501.761400014.520.10141419.6022.0446501.471500014.840.09731460.1040.5046502.691520014.900.09511445.52-14.584650-1600015.160.09121458.88-1.224650-11.70iS按规范规定的采用“变形比法”确定分层总和法地基压缩层深度,由该深度向上取的计算厚度(查表得)m0.8Z,则相应于12m11.2Z至,土层变形量理论计算为负,小于75.10.025iS,则计算到12m计算可行。持力层10MEs)(pa,取桩基础沉降计算经验系数1.2。桩基等效沉降系数按下式计算e:30.50.59ccbLBnn。,1,1533.3saCCBLdld查表得:5.457C1.415,C0.093,C210334.0457.52415.12093.0)1(1C210eCnCnbb基础最终沉降量:mmse10.2811.702.1334.0S'l5.单桩结构设计1).混凝土:混凝土标号选C30,满足水下要求和预制桩尖。混凝土保护层厚度取50mm,满足水下要求。2).钢筋:单桩的最大轴向压力为:kNxyMyyMnGFiyix4.767260.25007.734N22max2maxmaxAfkNNc4.776maxsaf只需按构造配筋,安全等级为二级;主筋用6根12,入承台锚固长度取420mm35d,伸入桩身全长9m;箍筋用8@300,且用螺旋箍筋。6.承台设计1)承台构造承台形式为柱下独立版式承台;尺寸(方形):100050005000,承台边距最近桩边200mm;承台埋深1500mm;承台混凝土强度等级取C30,取243.1mmNft;配置HRB335级钢筋,取2300mmNfy;钢筋保护层取mm70,有效高度mmh9300;柱子截面尺寸2504600mm;桩顶嵌入承台深度mm100。2)承台受冲切承载力验算:⑴承台受弯承载力计算:mkNbyNmkNaxNkNxxMnFNoioijiiiyji2.3313)225.02(2.6223)2(M9.3385)3.02(9.6633)2(M9.6637.412.6222625009560022向均匀布置。沿平行,选用配筋方向(长向)按xxmmmmhfxxoysI,15700A20053.134849303009.0109.33850.9MAM2s26则向均匀布置。沿平行,选用配筋方向(短向)按yymmmmhfyy,15700A20057.13484)20930(3009.0102.33130.9MAMy2s26,0s⑵柱边冲切,计算模型如下图冲切力:kNNFil8.4977956005600F受冲切承载力截面高度影响系数:983.0)8001000(80020009.011hp冲跨比与系数计算:。,则均大于oooxooyoxhaahaay;14753002252000;140030000320007.02.084.01.0.01oxoxoyoxoyooxha,kNhfahabthpoxcoyoycox6.718393.01430983.0)]4.16.0(7.0)475.145.0(7.0[2)]()([20满足要求⑶角柱冲切kN9.663Nmax467.02.056.00.1;0.10.1;8.0oxox111121oyoyyoxxyxmaamcc则:kNhfacacthpxyyx3.227793.01430983.0)]5.08.0(467.0)5.08.0(467.0[)]2()2([0111121角柱抗冲切满足要求。⑷承台受剪承载力计算受剪切承载力截面高度影响系数hs计算0.96393080041hs)(①.对-斜截面:505.193014000haxx剪切系数:70.02.5051.751.01.75kNhbfot7.19919.66334.448293.00.5143070.0963.00hs满足-斜截面承载力。②.-斜截面63.12593014750ydhax剪切系数:0.6652.631.751.01.75kNkNhbfot1866.62.22638.4143059.00.51430656.0963.00hs满足-斜截面斜截面承载力。⑸局部承压验算由于承台的混凝土强度等于柱的混凝土强度,按规范进行验算。柱子截面面积:2t27.045.06.0Am局部受压净面积:2t1n27.0AAm局部受压计算面积:243.2)45.03()6.03(Amb混凝土的局部受压强度提高系数:327.0
本文标题:灌注桩基础工程课设
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