טכניון מכון טכנולוגי לישראל
הטכניון מכון טכנולוגי לישראל - בית הספר ללימודי מוסמכים  
M.Sc Thesis
M.Sc StudentChacha Aaron
SubjectA Model to Assess the Load Acting on a Buried Structure
DepartmentDepartment of Civil and Environmental Engineering
Supervisors Professor Avraham Dancygier
Dr. Yuri Karinski
Full Thesis text - in Hebrew Full thesis text - Hebrew Version


Abstract

Buried and underground structures are an inseparable part of the building industry, from ancient times to this day. These structures function as infrastructure, transportation tunnels, for security purposes and more. An essential part of the design of structures involves the verification of their ability to withstand the loads acting on them. Throughout the years it was discovered that in the context of buried structures, evaluation of the acting load involves an interaction between the structure and the soil in which it is buried. This phenomenon develops due to the discontinuity within the soil medium caused by the structure, which creates a change in the stress distribution in the soil. The deflection of the structure's roof influences the load acting on it, while at the same time this deflection is caused by the load. This soil-structure interaction which comprises redistribution of the stress field in the soil, is also known as 'soil arching'.

In this study, the behavior of buried structures was investigated, especially in context of the contact pressure acting on them. This study is based on a simplified model in which the structure is characterized by an equivalent two-degree of freedom system representing the deflections at the center of the structure's roof and floor. The soil above the structure is represented by a one-dimensional column, subjected to axial external pressure and to shear tractions, which represent the interaction between the structure and the soil medium. The model has been developed for the evaluation of the average contact pressure acting on the structure's roof and the deflection at its center.

The original model has been developed to represent structures with only flat roof and floor. Additionally, in the original model the shear tractions that act on the soil column, have a linear relation with the difference between the deflection of the soil over the structure and the soil in the free-field (i.e., soil without the presence of the structure).

The aims of this study were to improve the existing model with reference to the two aspects mentioned above. That is, this study was aimed at description of a non-linear relation between the shear tractions and the deflections in the soil and at expanding the model's ability to simulate structures with curved roof and/or floor.

The model was verified against experimental results and showed somewhat better predictions than the original model.