|M.Sc Student||Klein Boaz|
|Subject||Prediction of 3D Tunneling Induced Ground Displacements|
in Saturated Clays using the Mobilized Strength
|Department||Department of Civil and Environmental Engineering||Supervisor||Professor Assaf Klar|
|Full Thesis text|
In recent years, the growth of population has led
to a rapid development of urban areas as the demand for residential and
commercial areas has increased. Subsequently, tunneling has become widely used
as the infrastructures and public utilities have had to make way for other
urban facilities and have been forced to go underground.
The urban areas density, their foundation and other underground utilities, entail a
large effort from the geotechnical and structural engineers to study the effect of tunneling on existing structures in order to assess the expected damage induced by tunnel excavations.
A first assessment of the tunneling induced risk to the structure is usually based on
the preliminary evaluation of the greenfield settlement trough which is developed due
to the tunnel excavation. The greenfield displacements may later be used for a more
complex analysis of the soil-structure interaction. The tunneling induced greenfield settlement trough has been studied thoroughly throughout the last few decades and many attempts were made in order to determine its shape and magnitude. While most of the methods are essentially empirical, based on data obtained from different tunneling projects, analytically based methods are not commonly used and usually involve some empirical features or the assumption of the soil being linear elastic. The difficulty of solving analytically geotechnical problem while considering the nonlinear nature of the soil is not limited to the tunneling problem, but is rather general. Closed form analytical solution of the nonlinear problems are nearly impossible. The relatively new Mobilized Strength Design (MSD) concept provides a methodology to generate a simple, closed form, plasticity and energy based solution for complicated nonlinear geotechnical problems. While the MSD concept is general, its application to specific geotechnical problem is not straightforward and requires an intensive developments and treatment to reach a simplified solution for engineering use.
This thesis follows the MSD concept to develop a three-dimensional mobilized strength design formulation for evaluating the face take’ volume loss of an advancing tunnel.