Research On Structural Behaviour Of Geogrid Reinforced Soil Retaining Wall Under Static Or Dynamic Loads

The internal force and the form of reinforced soil retaining wall (RSW) used in high speed railway change due to static loads of self gravity and rail system and dynamic load of train travelling. Inorder to realize the distribution of stress and deformation of geogrid RSW used in high speed railway, this paper has conducted systematic research on structural behavior and its evolution process, key aspects affecting RSW, theory calculation methods of settlement and horizontal displacement of RSW and so on relying on project of Qingdao-Rongcheng intercity railway.Based on finit element analysis, aspects affecting distributions of deformation and safety factor of RSW have been analyzed. Having presented that load condition, vertical distance and length of reinforcement, interface friction coefficient between reinforcement and soil are the main controlling elements affecting deformation and safety factor of RSW.Composite elastic moduli and shear moduli of reinforced soil have been deduced using the method of numerical analysis, which considered the effect of relative displacement between reinforcement and soil. On calculation of horizontal displacement of RSW face, firstly the calculation method of reinforcement tensile deformation has been presented based on slip line field theory which considered the non-associated flow rule. Secondly the composite moduli of reinforced soil has been used in calculation of RSW bending and shear deformation, which considered the effect of relative displacement between reinforcement and soil, and this method has made the calculation simplifying. Thirdly based on theory of deflection calculation of cantilever beam, the calculation method of horizontal displacement of wall face under top local load has been deduced. On settlement calculation of RSW top face, firstly the consolidation settlement has been calculated using layer wise summation method which adopted the composite moduli. Secondly calculation method of settlement caused by horizontal displacement without surcharge load has been deduced using calculation formula of horizontal displacement. Thirdly based on methods above, settlement calculation method under top local load has been presented.Distribution and evolution of stress and deformation of RSW with wrapped face or concrete-block panel under static or dynamic loads have been revealed by laboratory model test, numerical simulation and in-site test. Results have shown conclusions that static or dynamic soil pressure which included vertical soil pressure and horizontal soil pressure presented nonlinear distribution, the max-value was located in middle portion of reinforcement (without surcharge load) or near loading position (under surcharge load). The diffusion angle of additional stress was between 50° and 70°. The test position of potential slip face was further to the wall face than the position predicted by method of "0.3H", and it was near to the plane between which and horizontal plane has an angle of 45°+ψ/2 and ψ is dilation angle of soil. The attenuation of dynamic soil pressure in RSW was faster than that in retaining wall without reinforcements.