(4-下面计算沉降量的方法是《建筑地基基础设计规范》（GBJ7-89）所推荐的，简称《规范》推荐法，有时也叫应力面积法。（一）计算原理应力面积法一般按地基土的天然分层面划分计算土层，引入土层平均附加应力的概念，通过平均附加应力系数，将基底中心以下地基中 Z.-Z.深度范围的附加应力按等面积原则化为相同深度范围内矩形分布时的分布应力大小，再按矩形分布应力情况计算土层的压缩量，各土层压缩量的总和即为地基的计算沉降量。理论上基础的平均沉降量可表示为g=2Z 骂=2L 乎■(玄「旳-弓一®$i-L2-16式中：S--地基最终沉降量（mm）；n--地基压缩层（即受压层）范围内所划分的土层数；P。一基础底面处的附加压力（kPa）；E--基础底面下第 i 层土的压缩模量（MPa）；si,,z、z—分别为基础底面至第 i 层和第 i-1 层底面的距离（m）；ii-1..a.、a.「-分别为基础底面计算点至第 i 层和第 i-1 层底面范围内平均附'加应力系数，可查表 4-1。B1.01.21.41.61.82.02.42.83.23.64.05.0>100.1.001.001.001.001.001.001.001.001.001.001.001.001.00000000000000000.0.990.990.990.990.990.990.990.990.990.990.990.990.99178888888888880.0.980.990.990.990.990.990.990.990.990.990.990.990.99270122233333330.0.960.970.970.970.970.970.980.980.980.980.980.980.98373689900111120.0.930.940.950.950.950.960.960.960.960.960.960.960.96467368512233330.0.900.910.920.920.930.930.930.930.930.940.940.940.94505493579900000.0.850.870.890.890.900.900.910.910.910.910.910.910.9168808360234455z/L/B表 4-1 矩形面积上均布荷载作用下，通过中心点竖线上的平均附加应力系数«0.0.810.840.850.860.870.870.880.880.880.880.880.880.88760551614567780.0.770.800.810.830.830.840.850.850.850.850.850.860.86851919415789000.0.730.760.780.790.800.810.820.820.820.830.830.830.83954476316901231.0.690.720.740.760.770.780.790.790.800.800.800.800.80083945328134671.0.660.690.710.730.740.750.760.770.770.770.770.780.78134734341579021.0.630.660.680.700.710.720.730.740.740.750.750.750.75213635574924681.0.600.630.650.670.680.690.710.710.720.720.730.730.73313748819580351.0.570.600.620.640.660.670.680.690.700.700.700.710.71435981276158141.0.540.580.600.620.630.640.660.670.670.680.680.690.69580427346936031....
