單向分層總和法計(jì)算基礎(chǔ)中點(diǎn)最終沉降量案例

單向分層總和法計(jì)算基礎(chǔ)中點(diǎn)最終沉降量案例單向分層總和法計(jì)算基礎(chǔ)中點(diǎn)最終沉降量已知柱下單獨(dú)方形基礎(chǔ)，基礎(chǔ)底面尺寸為2.5×2.5m，埋深2m，作用于基礎(chǔ)上(設(shè)計(jì)地面標(biāo)高處)的軸向荷載N=1250kN，有關(guān)地基勘察資料與基礎(chǔ)剖面詳見下圖。試用單向分層總和法計(jì)算基礎(chǔ)中點(diǎn)最終沉降量。解:按單向分層總和法計(jì)算(1)計(jì)算地基土的自重應(yīng)力。z自基底標(biāo)高起算。當(dāng)z=0m，σ=19.5×2=39(kPa)sDz=1m，σ=39+19.5×1=58.5(kPa)sz1z=2m，σ=58.5+20×1=78.5(kPa)sz1z=3m，σ=78.5+20×1=98.5(kPa)sz1z=4m，σ=98.5+(20-10)×1=108.5(kPa)sz1z=5m，σ=108.5+(20-10)×1=118.5(kPa)sz1z=6m，σ=118.5+18.5×1=137(kPa)sz1z=7m，σ=137+18.5×1=155.5(kPa)sz13(2)基底壓力計(jì)算?；A(chǔ)底面以上，基礎(chǔ)與填土的混合容重取γ=20kN/m。0(3)基底附加壓力計(jì)算。(4)基礎(chǔ)中點(diǎn)下地基中豎向附加應(yīng)力計(jì)算。用角點(diǎn)法計(jì)算，L/B=1，σ=4K?p，查附加應(yīng)力系數(shù)表得K。zisi0si(5)確定沉降計(jì)算深度zn考慮第?層土壓縮性比第?層土大，經(jīng)計(jì)算后確定z=7m，見下表。n例題4-1計(jì)算表格1zzσσ/σzσzszzsznKs(m)B/2(kPa)(kPa)(%)(m)000.25002013910.80.1999160.758.521.60.112390.2978.532.40.064251.6298.843.20.040132.24108.529.7154.00.027021.71118.518.3264.80.019315.5213711.3375.60.014811.90155.57.6按7m計(jì)(6)計(jì)算基礎(chǔ)中點(diǎn)最終沉降量。利用勘察資料中的e-p曲線，求按單向分層總和法公式計(jì)算結(jié)果見下表。例題4-1計(jì)算表格2附加應(yīng)力自重應(yīng)力z平均值H平均值ee12(kPa)(kPa)(kPa)(cm)(m)(cm)-1(kPa)(kPa)(kPa)(cm)(kPa)03920110048.75180.85229.60.710.640.00038744184.09158.5160.710068.50125.501940.640.610.00023968611.835.92278.590.2910088.5070.96159.460.6350.620.00021177490.926.84398.551.62100103.541.93145.430.630.620.00023868480.617.454108.532.24100113.526.98140.480.630.620.00037143930.618.065118.521.71100127.518.62146.120.690.680.00053731470.598.65613715