5.3.3 Bowles's method
Bowles（1988）suggested a procedure to estimate excavation⁃induced ground surface settlements，which can be described as follows（Figure 5.10）：
①Compute the lateral displacement of the wall using the finite element method or the beam on elastic foundation method.
②Compute the area of the lateral wall deflection（act）.
③Estimate the influence range of ground surface settlement（D）following Capse's method（1966）：
D＝（He＋Hd）tan（45°－φ／2）
Figure 5.9 Clough and O’Rourke's method（1990）for estimating ground surface settlement
Figure 5.10 Bowles's method（1986）for estimating ground surface settlement
where He＝the excavation depth，Hd＝B ifφ＝0 and Hd＝0.5 B tan（45°＋φ／2）ifφ≥0，B＝the excavation width.
④Maximum ground surface settlementδvm＝4ad／D.
⑤The ground surface settlementδv is assumed to be parabolicδv＝δvm（lx／D）2.