PARAMETRIC STUDIES FOR OBTAINING THE DIMENSION OF SOIL IMPROVED AREA

Abstract

In many cases, to improve weak soil (e.g. grouting method or other method), it must have the obvious understanding about the design of appropriate size of soil improved area, for example, road projects or deep excavation projects. The essential input parameters are a certain width, a depth, and also the improved area stiffness. The important question is why it is generally recommended to make deeper area than performing wider area. This question can be answered with parametric studies by using the Beam on Elastic Foundation Method which is proposed by Hetenyi (1946). Soil in this method is modeled as Winkler's spring. And also, the relevant information of the soil settlement related to the soil stiffness and that spring could be analyzed with this approach. In this paper, the design chart is developed with considering several of simple combinations among the contact load pressures, the appropriate sizes, and the stiffness of improved area (e.g. improved soil modulus). So, the deeper improved soil is simulated and shown that if the improved soil thickness is increased, the settlement will be reduced. But, for another case with particular loading condition and soil stiffness, there is no effect if the area of improved soil is wider and the behavior is similar and goes through the same one pattern only. In this paper, it is developed the design curve considering the load acting on the improved soil area, modulus of improved area parameters and soil modulus of subgrade reaction, the normalized curve for getting improved area thickness and width is generated. It is shown if the load is increased then the width of improved soil area has to be increased for a certain thickness. Because of linear elastic approach, it is shown that the variation of five parameters (soil modulus, of improved area, load, thickness and length of improved area, and modulus of subgrade reaction) gives the same curves for each combinations of certain value of k/su. Using this normalized design chart as a function of pressures, width of loading, a soil width and thickness, and soil stiffness, it can be used as the appropriate preliminary dimension of improved soil area.