基础工程3-3

3-3某场地土层分布情况自上而下为：①杂填土，厚度为1.0m，②淤泥，软塑状态，厚度为6.5m,qs2a=6.5kPa，③粉质黏土IL=0.25，qs3a=40kPa，qpa=1800kPa，厚度较大。上部结构柱传至地面处的荷载设计值为：竖向力F=2500kN，弯矩M=180kN˖m，水平力H=100kN。初选预制桩截面为350mm350mm。试设计该桩基础。方案一㈠确定桩长初选承台高度为1m，桩进入承台0.1m。桩进入持力层：由黏土2d=20.35=0.7(m)取1.4m。桩长=6.5+0.1+1.4=8(m)l㈡确定单桩竖向承载力Raap2paR=40.35=1.4(m)0.350.350.1225(m)R1.4(6.56.51.440)0.12251800358.05(kN)siaipaqlqAA㈢计算桩数及承台布置,,2500n7358.05n(1.11.2)n8kaFR（根）（根）桩的布置图如下：㈣桩基受力验算：n3.12.7120167.4(kN)2500167.4333.425(kN)358.05kN8kkkkkaFGQGQRmaxmax2min22aM(1801001)1.2333.42541.220.6385.3(kN)1.2R430(kN)281.57(kN)0ykkixQQx满足要求。方案二㈠确定桩长初选承台高度为1m，桩进入承台0.1m。桩进入持力层：由黏土2d=20.35=0.7(m)取4.4m。桩长=0.1+5.5+4.4=10(m)l㈡确定单桩竖向承载力Raap2paR=40.35=1.4(m)0.350.350.1225(m)R1.4(5.56.54.440)0.12251800517(kN)siaipaqlqAA㈢计算桩数及承台布置,,2500n5517n(1.11.2)n6kaFR（根）（根）桩的布置图㈣桩基受力验算：n1.72.7220183.6(kN)2500183.6447.3(kN)517kN6kkkkkaFGQGQRmaxmax2min2aM(1801001)1447.341517.3(kN)1.2R620.4(kN)377.3(kN)0ykkixQQx满足要求。