Paper Title
A Study On The Characteristics Of Stress Release Zone According To Diameter Of Steel Pipes By Non-Open Cut Method

Subsurface constructions can be classified into two methods such as open cut method versus non-open cut method. Open-cut method can bewidely applied to construct underground structures, but it raises several problems which are traffic jam, relocation expenses of existing obstruction, and so on. For these reasons, the use of non-open cut method has been gradually increased to subsurface structure construction underneath railways and roads nowadays.The non-open cut method usually uses 0.8 to 2.0 meter diameters of steel pipe. When a steel pipe is press-fitted into the ground, the stress conditions such as earth pressures are changed and deformation of soil mass is occurred which causes settlements at surface around the construction area.Therefore, it is necessary to develop a method that can minimize the stress release zone and maintain the stress equilibrium state of ground.In this study, laboratory tests were conductedto determinea stress release zone according to diameter variation of steel pipes used for non-open cut method. Three-dimensional finite element analyses for each construction stage were performed to examine the stress changes in soil mass. The displacementsin the ground were also investigated by numerical analysis. The results of the numerical analysis indicate that the diameter of press-fitted steel pipe is one of the most important factors on the behavior of the ground around the non-open cut method applied. Index Terms - Non-open cut method, Stress release zone, three-dimensional numerical analysis