单向分层总和法计算基础中点最终沉降量案例

1、精品文档单向分层总和法计算基础中点最终沉降量已知柱下单独方形基础，基础底面尺寸为2.5&5m,埋深2m,作用于基础上(设计地面标高处)的轴向荷载N=1250kN,有关地基勘察资料与基础剖面详见下图。试用单向分层总和法计算基础中点最终沉降量。39,0 m解土产坦义NM °泌口 kN设计也面42一口加嗡质黏土 产20kN,加门才7”精品文档7-18.5kN4n'卵石-,2。SkN4n'£=20.5kN/m'解：按单向分层总和法计算(1)计算地基土的自重应力。z自基底标高起算当z=0m,前=19.52=39(kPa)z=1m,血=39+19.51=

2、58.5(kPa)z=2m,m=58.5+201=78.5(kPa)z=3m,过=78.5+201=98.5(kPa)z=4m,血=98.5+(20-10)1=108.5(kPa)z=5m,m=108.5+(20-10)1=118.5(kPa)z=6m,如=118.5+18.5住137(kPa)z=7m,m=137+18.51=155.5(kPa)(2)基底压力计算。基础底面以上，基础与填土的混合容重取第=20kN/m3N+G1250+2.5x2,52x20p=240kpei尸25x25(3)基底附加压力计算。=240-19.5x2.0=201kPa(4)基础中点下地基中竖向附加应力计算。用角

3、点法计算，L/B=1,(rzi=4Ksip0,查附加应力系数表得Ksi0(5)确定沉降计算深度Zn考虑第层土压缩性比第层土大，经计算后确定zn=7m,见下表。例题4-1计算表格1z(m)zB/2Kscz(kPa)(Sz(kPa)(z/sz(%)zn(m)000.25002013910.80.1999160.758.521.60.112390.2978.532.40.064251.6298.843.20.040132.24108.529.7154.00.027021.71118.518.3264.80.019315.5213711.337L5.60.014811.90155.57.6按7m计(6

4、)计算基础中点最终沉降量。利用勘察资料中的e-p曲线，求按单向分层总和法公式计算结果见下表。例题4-1计算表格2zH自重应力附加应力平均值”州一阳钎里居d比(kPa)(kPa)平均值品(kPa)h瑞十丁匕(kPa)(kPa)%却5=(m)(cm)可(kPa)ae2(kPa-1)一父(cm)(cm)039201229.6158.5160.748.75278.590.29194398.551.6210068.50180.85159.460.710.640.00038744184.094108.532.2410088.50125.500.640.610.00023968611.835.925118.521.7110070.96145.430.6350.620.00021177490.926.84613715.52100103.541.930.630.620.00023868480.617.45100100113.526.98140.480.630.690.620.680.0003710.000537439331470.610.598.068.65715