CFG桩复合地基处理工程计算书

计算书：1、面积置换率计算依据《建筑地基处理技术规范》（JGJ79-2012），式中：——复合地基承载力特征值，取值为180kPa；——单桩承载力发挥系数，取0.80；——桩端端阻力发挥系数，取1.0；——面积置换率；——单桩承载力特征值（kN）；——桩截面积，Ap=0.09616m2（桩径d=0.35m）；——桩间土强度的发挥系数，按规范取0.90；——处理后桩间土承载力特征值，取值60kPa（桩间土按素填土取值）；——桩的周长；——桩侧土侧阻力特征值；——第i层土的厚度；——桩端端阻力特征值，（以可塑粘土、硬塑粘土、强风化泥质砂岩作为桩端持力层）。单桩承载力Ra计算和取值表代表性孔指标土层层厚桩侧土侧阻力特征值（kPa）桩端端阻力特征值（kPa）单桩承载力特征值（kN）ZK1素填土0.1212/267.79软塑粉质粘土1.9025/硬塑粘土2.4845950ZK3附近23轴线素填土1.4012/264.77可塑粉质粘土2.9030/硬塑粘土1.2045950ZK4附近素填土1.4012/264.77 36轴线硬塑粘土2.8045950ZK5素填土2.1312/261.38硬塑粘土2.8745950ZK7素填土5.0512/274.31可塑粘土4.4535380ZK8素填土3.0512/228.70可塑粘土3.9535380ZK11硬塑粘土2.5045950214.99ZK12素填土1.9412/267.72可塑粘土2.2035/软塑粉质粘土1.4025/硬塑粘土0.5645950ZK14素填土1.8012/273.34硬塑粘土3.2045950取值=200kN取=200kN进行计算。180≤0.8×m×200/0.09616+0.9×(1-m)×6012.12≤154.81mm≥0.0783m=0.0783，则单根桩承担的处理面积Ae=Ap/m=0.09616/0.0783≈1.228m2。2、桩位布置2/2式中：m——实际置换率；n——同一承台内桩数量；AP——桩截面积，0.09616m2（桩径d=0.35m）；A——承台面积；d——桩身平均直径(m)；de——一根桩分担的处理地基面积的等效直径(m)；正方形布桩de=1.13s，矩形布桩de=1.13，s、s1、s2分别为桩间距、纵向桩间距和横向桩间距。 CFG桩复合地基设计桩布置楼号序号承台类型承台尺寸(mm)桩位间距(mm)桩径一个承台CFG桩根数实际置换率m桩顶标高（±0标高下）1#楼1DJJ-011900x19001100x1100350mm4根0.1065-2.10m(局部2.6m)2DJJ-022400x2400900x1300350mm6根0.10013DJJ-032700x3200950x1100350mm9根0.10014DJJ-042300x3600850x1300350mm9根0.10455DJJ-0510400x39001100x1100350mm40根0.09486DJJ-063000x41001100x1100350mm12根0.09387DJJ-072500x4000950x1100350mm12根0.11538DJJ-083100x44001150x900350mm15根0.10579DJJ-094300x55001150x950350mm24根0.097510DJJ-102800x43001000x1200350mm12根0.095811DJJ-113000x47001150x1000350mm15根0.102212DJJ-122100x21001100x1100350mm5根0.10902#楼1DJJ-011900x19001100x1100350mm4根0.1065-1.60m2DJJ-022400x2400900x1300350mm6根0.10013DJJ-032800x28001000x1000350mm9根0.11034DJJ-041300x1300800x800350mm4根0.22755DJJ-0510400x39001100x1100350mm40根0.09486DJJ-063000x41001100x1100350mm12根0.09387DJJ-072500x4000950x1100350mm12根0.11538DJJ-083100x44001150x900350mm15根0.10579DJJ-092300x3600850x1300350mm9根0.104510DJJ-102800x43001000x1200350mm12根0.095811DJJ-112300x5400850x1200350mm15根0.116112DJJ-124300x55001150x950350mm24根0.097513DJJ-132700x3200950x1100350mm9根0.100114DJJ-142300x3600850x1300350mm9根0.104515DJJ-151900x34001100x900350mm8根0.1190以上布桩均满足式中：m——实际置换率；m——实际置换率；n——同一承台内桩数量； AP——桩截面积，0.09616m2（桩径d=0.35m）；A——承台面积。根据以上单桩承载力计算可知，按上表桩间距布置CFG桩，有效最短桩长不应小于2.5m，才能满足上部荷载的要求，复合地基承载力特征值fspk≥200kPa。3、桩体强度选择依据《建筑地基处理技术规范》（JGJ79-2012）式中：fcu——桩体混合料试块28d立方体抗压强度平均值。——单桩承载力发挥系数，取0.80；AP——桩截面积，0.09616m2（桩径d=0.35m）——单桩承载力特征值200（kN）；经计算：fcu≈6655.57kPa，因成桩工艺选用长螺旋中心压灌成桩，故选用C20砼。4、复合地基承载力验算(1)根据式中：m——实际置换率；n——同一承台内桩数量；AP——桩截面积，0.09616m2（桩径d=0.35m）；A——承台面积；并根据各类型基础CFG桩布桩形式及桩距，经计算，复合地基面积置换率m值均可满足设计要求；(2)复合地基承载力验算式中：——复合地基承载力特征值；——单桩承载力发挥系数，取0.80；——面积置换率，计算时取实际置换率，见布桩大样图；——单桩承载力特征值（kN）；——桩截面积，Ap=0.09616m2（桩径d=0.35m）；——桩间土强度的发挥系数，按规范取0.90； ——处理后桩间土承载力特征值，取值60kPa（桩间土按素填土取值）；复合地基承载力计算结果见下表。复合地基承载力计算结果表楼号基础型号实际面积置换率m单桩承载力特征值Ra（kN）按最不利考虑处理后的桩间土承载力特征值fsk（kPa）按最不利考虑单桩承载力发挥系数λ桩间土强度发挥系数ß复合地基承载力特征值fspk（kPa）1#楼DJJ-010.1065264.77600.800.90282.84DJJ-020.1001269.70600.800.90273.20DJJ-030.1001274.40600.800.90277.11DJJ-040.1045260.16600.800.90274.54DJJ-050.0948267.10600.800.90259.54DJJ-060.0938274.30600.800.90262.99DJJ-070.1153278.10600.800.90314.54DJJ-080.1057228.43600.800.90249.17DJJ-090.0975261.81600.800.90261.10DJJ-100.0958245.06600.800.90244.14DJJ-110.1022228.43600.800.90242.70DJJ-120.1090261.74600.800.90285.472#楼DJJ-010.1065214.99600.80.9238.74DJJ-020.1001224.88600.80.9235.87DJJ-030.1103262.58600.80.9289.00DJJ-040.2275257.19600.80.9528.49DJJ-050.0948264.67600.80.9257.62DJJ-060.0938334.78600.80.9310.19DJJ-070.1153273.35600.80.9309.98DJJ-080.1057364.89600.80.9369.16DJJ-090.1045265.44600.80.9279.13DJJ-100.0958295.36600.80.9284.23DJJ-110.1161340.75600.80.9376.86DJJ-120.0975272.62600.80.9269.87DJJ-130.1001219.94600.80.9231.76DJJ-140.1045224.88600.80.9243.86DJJ-150.1190323.22600.80.9367.57根据计算结果，其加固后的复合地基承载力特征值均大于180kPa。满足设计要求。 5、压缩模量地基处理后的变形计算应按现行的国家标准《建筑地基处理技术规范》（JGJ79-2012）的有关规定执行，复合地基的压缩模量等于该天然地基压缩模量ξ倍，按勘察报告提供的桩间土承载力特征值（素填土）fak=60kPa。ξ=fspk/fak（fspk为处理后的复合地基承载力，ξ为压缩模量提高系数）,各土层处理后的压缩模量详见表6。 6、复合地基沉降和变形计算本工程根据场地地质条件和上部结构荷载选取最不利位置进行估算。根据《建筑地基基础设计规范》(GB50007-2011)，《建筑地基处理技术规范》（JGJ79-2012）公式：，，，计算变形量；式中：——地基最终变形量(mm)；——按分层总和法计算出的地基变形量(mm)；——沉降经验系数，根据变形计算深度范围内压缩模量的当量值()、基底附加压力按《建筑地基处理技术规范》（JGJ79-2012）表7.1.8取值；N——地基变形计算深度范围内所划分的土层数；——相应于作用的准永久组合时基础底面处的附加压力(kPa)；——基础底面下底i层土的压缩模量(MPa)；——基础底面至第i层土、第i-1层土底面的距离(m)；——基础底面计算点至第i层土、第i-1层土底面范围内平均附加应力系数；——压缩模量当量值；Ai——第i层土附加应力系数沿土层厚度的积分值；——变形计算深度，应大于复合土层的深度(m)，计算深度范围内遇基岩时取至基岩表面；b——基础宽度(m)；——在计算深度范围内，第i层土的计算变形值(m)； ——在计算深度范围内向上取厚度为的土层计算变形值，按《建筑地基基础设计规范》(GB50007-2011)表5.3.6取值(m)。沉降、相邻柱基沉降差计算表6-1计算项目土层P0(kPa)Zn(m)fak(kPa)fspk(kPa)压缩模量Es(MPa)计算压缩模量值Esi(MPa)模量提高系数ζzi4)(MPa)ψs(mm)S(mm)沉降差0.002L1#楼5剖面35轴线素填土18012.1603192.9015.425.321.640.24881.632114.020.44106.2546.754.775.50硬塑粘土19010.3154.855.323.750.24021.9709可塑粉质粘土1206.2433.205.325.350.22891.2955硬塑粘土19010.3154.855.326.200.22230.6146硬塑粘土19010.3110.311.008.280.20501.2766粉土1105.425.421.0012.100.17131.48761#楼5剖面36轴线素填土1809.8602872.9013.874.781.400.24911.395013.870.4495.4141.98硬塑粘土19010.3149.284.785.000.22853.1750硬塑粘土19010.3110.311.007.600.20591.6894粉土1105.425.421.009.800.18751.09062#楼11剖面7轴线素填土18014.0603242.9015.665.401.970.24851.958214.230.43122.8252.816.897.00可塑粘土1307.2839.315.402.780.24650.7829硬塑粘土19010.3155.675.403.540.24310.7012可塑粘土1307.2839.315.404.890.23371.1289软塑粉质粘土803.7620.305.405.900.23070.8733硬塑粘土19010.3155.675.407.500.21941.1375 硬塑粘土19010.3110.311.0010.600.19421.6521粉土1105.425.421.0014.000.17341.47632#楼11剖面9轴线素填土18016.0603482.9016.825.801.980.24831.966513.290.46129.8059.71可塑粘土1307.2842.225.802.30.24650.3013硬塑粘土19010.3159.805.804.40.23561.8788可塑粘土1307.2842.225.805.10.23260.5985软塑粉质粘土803.7621.815.805.90.22580.5838硬塑粘土19010.3159.805.806.50.22060.4067硬塑粘土19010.3110.311.0010.60.18692.1890粉土1105.425.421.00160.14971.6562经计算：相邻柱基的沉降差≤0.002L(L为相邻柱间距)，满足规范要求。沉降、整体倾斜计算表6-2计算项目土层P0(kPa)Zn(m)fak(kPa)fspk(kPa)压缩模量Es(MPa)计算压缩模量值Esi(MPa)模量提高系数ζzi4)(MPa)ψs(mm)S(mm)沉降差整体沉降差/L1#楼1剖面H轴线素填土18013.0602902.9014.024.830.140.24990.139911.050.55113.6862.523.800.0003软塑粉质粘土803.7618.164.832.020.24481.8380硬塑粘土19010.3149.804.834.500.22071.9946硬塑粘土19010.3110.311.005.900.20430.8489粉土1105.425.421.0013.000.13422.1569素填土18017.0602662.9012.864.432.100.24642.069811.760.52127.5466.32 1#楼1剖面A轴线硬塑粘土19010.3145.674.435.000.22252.3802硬塑粘土19010.3110.311.008.000.18901.5980可塑粘土1307.287.281.0013.600.14261.7094粉土1105.425.421.0017.000.12250.57262#楼7剖面N轴线素填土1806.4602762.9013.344.603.180.23222.953616.700.3550.9917.8544.190.0033软塑粉质粘土803.7617.304.604.080.22170.6646硬塑粘土19010.3147.434.606.100.19391.1130硬塑粘土19010.3110.311.006.400.18980.12772#楼7剖面A轴线素填土18017.6602722.9013.154.531.90.24741.880212.020.50124.0762.04可塑粘土1307.2832.984.534.10.23211.9262软塑粉质粘土803.7617.034.535.50.21440.9104硬塑粘土19010.3146.704.536.10.21180.4511硬塑粘土19010.3110.311.0010.70.16511.8984粉土1105.425.421.0017.60.11891.3043经计算：建筑物整体倾斜≤0.004，满足规范要求。