土力学习题答案第三章

3.1细砂、粗砂分界线处：16.4349.2CZkPa粗砂2/311enneen3(1)2.6510(10.2)19.08/112/3SwGwkNme水位线处49.219.082.494.8CZkPa粗砂与粘土分界处3()(2.652/3)1019.9/112/3SwsatGekNme94.8(19.910)2.1115.6CZkPa粘土0.60.62.731.6383()(2.731.638)1016.56/111.638SwsatGekNme粘土与泥岩分界处115.6(16.5610)3135.28CZkPa泥岩顶面135.28105.1186.28CZkPa3.2见图结论：随着地下水位的下降，土有效应力增大，使得变形会增加。3.4对基地面积为36mm，0200PkPa点号L/bz/bC04ZCP0200.250200121/1.50.228182.4222/1.50.170136323/1.50.12096424/1.50.08668.8525/1.50.06350.46240.04838.4对基地面积为12mm，0200PkPa点号L/bz/bC04ZCP0200.250200121/0.50.12096222/0.50.04838.4323/0.50.02419.2424/0.50.01411.2525/0.50.0097.262120.0064.8要画图结论：随着深度增加，土的附加应力减小；基础面积越小，减小的速度越快。3.6甲基础作用下：Z=6.5m，基地附加应力3002.516260APkPaA处l/b=0.6/0.6=1,Z/b=6.5/0.6=10.83,C=0.0042440.00422604.37ZACAPkPa同理B处122()2(0.020.015)2602.6ZBAPkPaC处122()2(0.0130.0062)2603.54ZCAPkPa甲基础作用下：Z=7.5m，基地附加应力3001.516276APkPaA处2(0.0160.01125)2762.62ZAkPaB处40.002752763.04ZBkPaC处2(0.010.005)2762.76ZCkPa故4.372.626.99ZAkPa2.63.045.64ZBkPa3.542.766.3ZCkPa3-8解：求U形基础形心座标，以X轴为对称轴矩形AⅠAⅠ=3×6=18m2XⅠ=1.5myⅠ=0矩形AⅡ，AⅡ=AⅢ=1×3=3m2XⅡ=XⅢ=4.5myⅡ=myⅢ=-4.5m3545.4325.118mXAii2243218mAimAXAxiii25.224/54/则偏心距me25.0225.2基础左端边缘距形心轴y’距离为mc25.21基础右端边缘距形心轴y’距离为mc75.32截面惯性距43235.58252.23123112/275.0363612/1mI3112625.2/5.58/mcIW3226.1575.3/5.58/mcIWkpaWMAFp07.326/25.06024/60//11kpaWMAFp54.16.15/25.06024/60//12；3-9解：条形基础乙kpadydAFp1041161202/20020/00条形基础甲kpapp4000条形基础作用下z，x/b=0,z/b=1.5,sz=0.4堆载作用下x/b=7/6,z/b=2/3,sz=0.12z=1040.4+4000.12=89.63.10道理同前，20.4ZkPa3-11解：0/bx5.12/3/bz查表2-64.0sz01.0sx竖向有效应力=竖向有效自重应力+竖向附加应力kpapszz601504.00kpazycz303)1020('竖向有效应力=60+30=90kpa水平向有效应力=水平向有效自重应力+水平向附加应力kpakczcx12304.00kpapsxzx5.115001.00水平向有效应力=12+1.5=13.5kpa3-12解：（1）三角形荷载abd在M点所产生的附加应力MbftcMbMaftzppp200202322.05.4//1aab15.4/5.4/aabz0375.02Maft33.03//1aab5.13/5.4/aabz0290.02Mbft3/3/1aab5.4/5.4/aabz051.0cMb000010035.02029.0051.030375.0ppppz（2）三角形荷载ghn在M点所产生的附加应力nMHtcHhgHGtzppp200102233.03//1aab5.13/5.4/aabz0215.01gGHt3/3/1aab5.4/5.4/aabz0510.0cHh67.05.1//1aab35.1/5.4/aabz0163.02nMHt000020083.00163.0051.020215.0ppppz0021012.0)0083.00035.0(ppzzz00000)367(20)245(20)174(20128.00163.02029.02300375.0223ppppppptztz