טכניון מכון טכנולוגי לישראל
הטכניון מכון טכנולוגי לישראל - בית הספר ללימודי מוסמכים  
M.Sc Thesis
M.Sc StudentNormand Eitan
SubjectReinforced Earth Walls - Inclusion of Advanced Aspects
in Rational Design
DepartmentDepartment of Civil and Environmental Engineering
Supervisor Professor Assaf Klar
Full Thesis textFull thesis text - English Version


Abstract


Reinforced soil walls systems are widely used in Israel and around the world as part of roads embankments, bridge abutments and landscaping. The extensive use of this type of structures accelerates the development of new and advanced design methods and building techniques.

This work proceeds a series of previously accomplished works by Baker & Klein (2004a, 2004b) and Klar & Sas (2009, 2010a) where a method for the analysis of reinforced soil walls which includes the interaction between the three components of the system (i.e. soil, reinforcement and the wall facing) was introduced. In Baker & Klein (2004a, 2004b), the indeterminacy of the system was solved using division factors, based on relative strength, while in Klar & Sas (2009, 2010a), the statically indeterminacy of the system was solved using minimization requirements on the kinematical compatibility between the reinforcement layers and the wall. The latter entailed a genetic type algorithm for the solution of the equations system. The original method had several limitations, among others; it required significant computational effort, it was limited to inextensible reinforcement only, there was no consideration of friction at the back of the wall etc.

The current work addresses the aforementioned limitations by improving the method through the use of an alternative algorithm. This algorithm involves the solution of differential equations representing the displacements of the reinforcement. This feature, in specific, was needed in order to account for the behavior of extensible reinforcement layers. The suggested algorithm involves a repetitive linear solution of the wall's displacements equations in a matric form, which accelerated the calculation procedure and enabled to support the inclusion of other advanced aspects headed by the extension to extensible reinforcement. A main conclusion that arises from this work is that the standards for the design of reinforced soil systems are over conservative in two ways. First, for most examined cases, the predicted maximum tensile values at each reinforcement layer are smaller than those obtained using the current standards, unless the wall is very flexible. This can lead to the use of different types of reinforcement in terms of the material of the reinforcing layers or its characteristics. Second, the profiles of the tension forces along the reinforcing layers show near zero tension force values along large portion of the layers. Such advanced design can result in shorter reinforcement layers, even though the layers' length in the current standards is determined to be constant and certain, based on the height of the wall.