Abstract
Deformation of earth-retaining walls used in excavations in clayey soil is less when the walls are constructed through ground improvement and strut preloading. At the same time, earth pressure on the backside of the walls is greater than it is when the above methods are not employed. In such cases, the design method cannot incorporate the assumption that the earth pressure on the backside is a known value independent of the displacement of the wall. The use of a calculation method which assumes a ground spring on the backside may be considered, but no method of determining the horizontal subgrade reaction coefficient and minimum earth pressure on the back side has been established. This paper proposes a method to determine the horizontal subgrade reaction coefficient and minimum earth pressure on the basis of a numerical calculation result according to the finite element method. This paper goes on to discuss the results of applying this proposition to two sites: a site with improved ground on the excavation side and one in which the strut preload method was used
