Numerical Simulation And Optimization Design Of Retaining Wall Reinforced With Geogrids

Geogrid-reinforced retaining walls are widely used in various fields,such as highway,railway,architectural engineering, hydraulic engineering and so on,because of its remarkableeconomical benefits, convenience, adaption to foundation, simplicity of foundation treatment,good vibration resistance, shapely configuration and stability are not well settled inapplication of geogrids-reinforced soil retaining wall.Based on the reinforced retaining wall for He-Chi airport, using the finite elementanalysis software ADINA, build a model with grids and soil separated, to discuss force anddeformation characteristics of high geogrid reinforced retaining wall under different hight ofsoil and different load level. Meanwhile, we find out the effect of lateral displacement ofretaining wall, from three aspects, such as soil properties、reinforcement and retaining wall’sform and structure. Through analysis, some conclusions and suggestions are provided todesign and construction of reinforced retaining wall.The main work in this paper is as follows:(1) Review the development and Research status on reinforced retaining wall, summarizesorts and engineering characteristics of reinforcement materials, discuss the interfacecharacteristics and between geogrids and soil, reinforcement mechanisms and design methodsof reinforced structure.(2) Through large-scale triaxial test, direct shear friction test and pull out tests, discussthe macroscopic strength properties of soil reinforced with different geogrid, interfacecharacteristics and the tensile strength of reinforced material, and try to have a more profoundunderstanding of geogrids reinforcement mechanism, and also provide related parameters forthe subsequent numerical calculation.(3) Using finite element analysis software ADINA, based on the reinforced retaining wallof He-Chi airport, established a numerical model to simulate filling and loading process stepby step, in which the grille using elastic and linear rebar unit, without considering the relativedisplacement between reinforced and soil. Through the analysis, knowned stress and straindistribution rule of reinforced retaining wall, the plastic zone distribution, geogrids tension distribution and fracture surface of retaining wall. Calculation shows that: the stressdistribution of retaining wall became uniformitied, displacement, especially lateraldisplacement was under control, the plastic area turn smaller, the overall stability of thestructure was enhanced.(4) Still with the4levels wall of He-Chi airport l, to study the effect on the lateraldisplacement by soil’s nature (c, φ, ρ, and s), reinforcement condition (the reinforcementlength L, reinforcement spacing d, geogrids’ elastic modulus g), retaining wall’s form (heightH and width d of each step, and slope of wall) and construction measures, such as:amplification foundation at wall toe, cushion setted.(5) According to the sensitivity analysis, it is concluded that selection principle of soiland reinforcement material, reasonable reinforcement length and interval, the optimal formand structural measures of retaining wall.For packing soil, should have priority to choose gravel with good gradation class, and thechoice of steel should own enough tensile strength, and have very good friction interlockcapability with soil. Reasonable length of geogrids reinforcement is0.5~0.7times of wall,while0.4m to0.5m reinforcement interval is better. The stress and strain of retaining wall’ bottom is larger, therefore, the reinforcement can be encrypted or extended, in order to ensurethat the geogrids can provide enough anchoring force, constraint soil deformation, enhancethe overall stability of retaining wall. For reinforcement high retaining wall, generally usesthe classification of slope, single stage height had better without more than15m, with thesteps width3m~5m, and slope controlled in70o~80o.Then breakthrough plastic zone ofcan be not easily to formed, and less area will be occupied. In addition, horizontaldisplacement is the largest in the toe of retaining wall, from which soil is easily to slip outcausing damage, so enlarged basement can be setted in toe to prevent retaining wallfromsliding failure.