14.415.216.018.020.00.03670.03490.03320.02970.02690.03980.03790.03610.03230.02920.04250.04040.03850.03450.03120.04480.04260.04070.03640.03300.04680.04460.04250.03810.03450.04860.04630.04420.03960.03590.05160.04920.04690.04220.03830.05400.05150.04920.04420.04020.05610.05350.05110.04600.04180.05770.05510.05270.04750.04320.05920.05650.05400.04870.04440.06190.05920.05670.05120.04680.06770.06500.06250.05700.0524(三)地基沉降计算深度zn1.地基沉降计算深度zn,可通过试算确定,即要求满足:≤(3)式中Δsi′——在计算深度zn范围内,第i层土的计算沉降值(mm);Δsn′——在计算深度zn处向上取厚度为Δz土层的计算沉降值(mm)。Δz见图4-9并按表3确定,按上式计算确定的zn下仍有软弱土层时,在相同压力条件下,变形会增大,故尚应继续往下计算,直至软弱土层中所取规定厚度Δz的计算沉降量满足上式为止。表3计算厚度Δz值基础宽度b/mb≤22<b≤44<b≤88<b≤1515<b≤30>30Δz/m0.30.60.81.01.21.52.当无相邻荷载影响,基础宽度在1~50m范围内时,基础中点的地基沉降计算深度zn也可按照下列公式计算:zn=b(2.5-0.4lnb)(4)式中b—基础宽度(m),lnb为b的自然对数。3.当沉降计算深度范围内存在基岩时,zn可取至基岩表面为止。
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