Abstract
In new projects at great depths, the ratio of the construction cost of a shaft to the total project cost has been increasing. However, because no specific design method has been established, the method for small- and medium-depth projects has been applied to temporary diaphragm walls for great-depth circular shafts. In these circumstances, the design load has been determined without sound scientific reasons. In the study presented in this paper, working earth pressures were estimated from stress resultant in the direction of the horizontal section of diaphragm wall, calculated using measurement data, and the estimated earth pressures were simulated by FEM analysis considering initial plastic deformation, to review the method of setting earth pressure in the design of diaphragm walls of great-depth circular shafts. As a result, the earth pressure coefficient was set at about 0.2, which ensures stability of the ground at great depths. In addition, this paper summarizes the concept of the method for setting design earth pressures as a function of the N value.
