טכניון מכון טכנולוגי לישראל
הטכניון מכון טכנולוגי לישראל - בית הספר ללימודי מוסמכים  
M.Sc Thesis
M.Sc StudentSas Tal
SubjectRational Design of Reinforced Soil Walls using Kinematic
Constraints
DepartmentDepartment of Civil and Environmental Engineering
Supervisor Professor Assaf Klar
Full Thesis text - in Hebrew Full thesis text - Hebrew Version


Abstract

This thesis presents an analytical method for the solution of reinforced soil walls in which the wall facing has a structural role. The three-component (soil-reinforcement-wall) system is statically indeterminate, and hence cannot be solved by equilibrium equations alone.

Therefore, an interaction model, incorporating factors that divide forces between the reinforcement layers and the wall, was introduced to solve the statically indeterminate system. The division factors are resolved such that the kinematic constraints of compatibility between the reinforcement layers and the wall are satisfied. This is achieved by solving an optimization problem in which the objective function includes the relative displacement between the reinforcement layers and the wall. The resultant system is fully coupled whereby upper reinforcement layers are affected by the behavior of lower layers. A non-dimensional parametric study was conducted on walls with 10 face blocks (9 reinforcement layers). Results are given in a normalized manner for cases in which the reinforcement pullout stiffness is uniform and linearly increasing with depth. Analysis results show that in cases where the wall is relatively stiff compared to the reinforcement, the upper reinforcement layers are clearly affected by the lower layers (this is a direct outcome of the fully coupled system). On the other hand, when the relative stiffness of the wall is low, the system behavior tends towards that of a hinged system, which is statically determinate.

A comparison was held to a more rigorous continuum analysis, FLAC. Results show that the new method is capable of replicating the behavior of the more rigorous system, with a good agreement on both the value of maximum tensile forces in the reinforcement and shear and bending moment distributions along the wall. This thesis shows that the new method has a certain advantage over continuum methods, such as finite element or finite difference, since it requires limited input data that can easily be obtained from field tests.

In conclusion a comparison was made between the new framework and existing design standards ( IS-1630, BS-8006, FHWA 1996).  Analysis results indicate that design codes, which do not explicitly consider the structural role of the facing in the calculation procedure, may be over conservative in certain cases. This result supports the argument for introducing the structural role of the facing into design procedures and hence providing more reliable and economical solutions.