Braced vertical sheeting is to be used for an open-trench excavation undertaken for the construction of a section of subway tunnel that extends through medium-stiff clay ( ). The excavation will be 12...

Braced vertical sheeting is to be used for an open-trench excavation undertaken for the construction of a section of subway tunnel that extends through medium-stiff clay ( ). The excavation will be 12 m deep and supported by three rows of struts. The top strut will be level with the ground surface, with the second strut 3 m down and the third strut 7 m down from the ground surface. The struts will be positioned at 3.5 m center-to-center spacings (plan view spacing). Calculate the force in each strut (ref. Figures 44, 45, and 46).