Determining The Subgrade Modulus According To Physical Properties And Shear Strength Parameters Of Soil

Abstract

In this thesis study; different from widely used but restricted number of existing approaches in the literature, subgrade reaction modulus is determined as a function of geometrical (width, thickness and length of foundation etc.), index (relative density, specific gravity, unit weight etc.), shear strength (cohesion, internal friction angle) or mechanical (Young’s Modulus, Poisson’s ratio etc.) properties of soil and foundation. Determining the subgrade reaction modulus has become one of the important issues at the phase of designing the foundation structures especially. Analyzing the superstructure and foundation structure as a whole complicates the solution and costs more time and effort. In accordance with aforementioned issues; structural members such as beams resting on elastic soil has been modeled and analyzed separately in numerical softwares such as SAP2000 and PLAXIS. Results obtained from these analyses, have been compared, consistency has been sought and models that converge to each other as numerical results have been assumed as elementary models. Among the outputs of PLAXIS and SAP, the maximum settlement value of beam resting on elastic soil has been chosen as the primary control parameter. Subgrade reaction modulus values corresponding to the different soil parameters have been transferred into tables. By taking into account the consistency of units, a formula has been proposed; subgrade reaction modulus values obtained from this formula has been compared with subgrade reaction modulus values that used in SAP analysis on a chart. By using “Maximum Likelihood Estimation” method, proposed formulation has been tried to be optimized.