单向分层总和法计算基础中点最终沉降量案例

单向分层总和法计算基础中点最终沉降量（设计地向标高处）的轴向荷载N=1250kN,有关地已知柱下单独方形基础，基础底面尺寸为2.5x2.5m.埋深2m,作用于基础上基勘察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址。35.0mv—330m7=20.2N加'£-20.SkHrm*37.0inISO230QOO解：按单向分层总和法计算计算地基上的自重应力。2自基底标高起算。当z=Om,<7,0=19.5x2=39(kPa)7=lm,心1=3419.5x1=58.5(kPa)?=2m,心1=58.5+20x1=78.5(kPa)?=3m,心尸78.5+20x1=98.5(kPa)<=4m.(7p=98.5+(20-10)x1=108.5(kPa)<=5m.<7^1=108.5+(20-10)x1=118.5(kPa)Z=6m,心i=l18.5+18.5x1=137(kPa)?=7m,a^i=137+18.5xl=155.5(kPa)基底斥力计算。基础底面以上，基础与填上的混合容重取Yo=2OkN/m»N+G1250+2.5x2.5x2x20“p=——=—_—二240kPaP2.5x25基底附加斥力计算。护°=p-yD=240-19.5x2.0=201kPa基础中点下地基中竖向附加应力计算。用角点法计算，UBf査附加应力系数表得K皿（5）确定沉降计算深度益考农第③层土用缩性比第②层上大.经计算后确定益=7m,见下表。例题4」计算表格1(m丿|ZB/2K,|-1隔)16：(kPa)Zg(%)13丿000.25002013910.80.1999160.75&521.60.112390.2978.532.40.064251.6298.843.20.040132.24108.529.7154.00.027021.71118.518.3264.80.019315.52137113375.60.014811.90155.57.6按7m计（6）计算基础中点最终沉降虽。利用勘察资料中的-p曲线，求好空土及虬=匕#加-Pli%按单向分层总和法计算结果见下表。例题4T计算表格22(tn)%(kPa)(kPa)H(cir)n亜应力平均(ft阳(kPa)附加应力平均血耳(kPa)巧z十云(kPa)旬°2心(kPa)冷(cm)(ca)(kPJ)03920110048.75ISO.S3229.60.710640.0003S711184.0915S.5160.710068-50125.501910.610610.00023968611.835.92—78.590.291008S.5070.%159.460.6350620.00021177490.926.84398.551.62100103.541.93145.43063n620.00023S68480.61745410S.532.24100113.526.9S140.IS0.630620.00037113930.618.06511S.521.71613715.52100127.513.62146.120.6906S0.00053731470.398.65■1155.511.90100146.2313.71159.96O.GS0670.00072923010.599.24