Design of MSE/soil nail hybrid walls under highspeed railway loads

This research is focused on numerical modeling of Ankara-Sivas High speed railway project – The high speed trains will passes above the wall with the maximum height of wall 14 meters. The sensitivity of the project leads to forecast the wall deformations, by numerical modeling of reinforced earth wall for two types of train. This is the first time the Reinforced earth wall has been used for High-speed railway support in Turkey. All the design technology and data which has been used and expressed here is exclusively belongs to Reinforced Earth Company and copying without permission is prohibited. The preliminary designs was prepared by the Reinforced Earth Company using the Valdez program, The Valdez program is specifically prepared to analysis the MSE wall for the design of Reinforced Earth walls. This program is user friendly and provides two type of design cross section rectangular and trapezoidal. Further more you can design tired wall with various setback for walls steps. The method of design of Valdez program is based on the limit state design procedures, which has just given the length of strips by applying defined safety factors. The program is not able to estimate the displacements in the walls because as previously mentioned, the designs were based on "Limit State" methods. Which is using the limits of the materials in design but does not take into account the strains formed by stresses. Therefore a new method to calculate the displacements is needed. In this project because of the sharp cuts which is formed by Basalt, the preliminary designs were done in three alternative and three individual method, Because of the importance of the project and heavy loads, this project was prepared by three alternative geometry and a numerical analysis of the reinforced walls system. Finite element method of analysis, are capable of calculating the displacements in any part of the defined system. This is done by the finite element program Plaxis 2016. The reinforced earth walls design, will design according to limit state method, and then will check by the numerical analysis to control the deformation. In the evaluating of the design parameters the Rock lab program is used, in addition the slide 5.0 is used to calculate the stability and safety of the project. The first case is the MSE wall with rectangular shape geometry. For the better understanding of the working system, the mentioned geometry is analyzed according to maximum and minimum material properties which is defined from company as a selected backfill material for this case, in addition for effect of other backfill properties from other cases and parametric comparison with them, three selected backfill are taken from three articles which is the properties of selected backfill is so close to this case.