In braced excavation, sheetpiling is constructed at the first place, followed by the installation of struts as excavation proceeds. Following the installation of first row of struts, the depth of excavation is small so that there is no major yielding of soils. However, as further excavation takes place, soils yield before the installation of nth row of struts. The first row of struts prevents yielding near the ground surface. As such, deformation of wall increases with depth with the smallest at the ground level. Owing to the effect of construction method of braced excavation, it differs from the deformation condition of Rankine’s theory. This is attributed to arching effects in which there exists upward redistribution of loads. The upper part of braced excavation is in the state of elastic equilibrium while the lower part is in the state of plastic equilibrium.
This question is taken from book named – A Self Learning Manual – Mastering Different Fields of Civil Engineering Works (VC-Q-A-Method) by Vincent T. H. CHU.
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