The Study On Retaining Wall Of Geosynthetics Reinforced Soil

Even though geosynthetic reinforced soil technology has been widely used in the field of geotechnical engineering,a great amount of engineering practices showed some drawbacks in conventional retaining wall structure with reinforced soil: heavy lateral deformation,concentrated stress of reinforcement material at the panel,less coordinated deformation,and longer reinforcement material requirement,etc.Many papers have indicated that the small-spacing GRS(Geosynthetic Reinforced Soil),which especially refers to a reinforced soil structure with a spacing of reinforcement less than 0.3m,could solve the problems in conventional retaining wall structure with reinforced soil.GRS structure has virtues of prominent binding effect on soil,light lateral deformation,simple and convenient and economical construction process,and relatively low requirements for the foundation bearing capacity.This paper studies the deformation rules of GRS retaining wall and the factors that influence its stability with the method combining numerical analysis and experimental research with a view to promoting applications of GRS retaining wall in practical engineering.The studies and conclusions in this paper are as follows:1)Establishing numerical model of reinforced soil retaining wall by using FLAC3 D to analyze the influences of different reinforcement spacing with 0.2 m,0.3m,0.4 m,0.6 m,0.8 m,and 1m on the work state of reinforced soil retaining wall.Studies have shown that,under 0.2m reinforced spacing,namely GRS retaining wall,the maximum tensile stress of reinforcement material is far below the allowable stress and the reinforcement-soil relative displacement is far small.Under other spacing,the binding effect of reinforcement strip on soil is weaker than 0.2m spacing.It shows that the binding performance of GRS reinforced soil structure with 0.2m spacing is better than conventional reinforced soil retaining wall,and the geosynthetics with low strength and low modulus can be adopted as GRS retaining wall reinforcement material in the design and construction.2)Establishing numerical model of GRS retaining wall by using FLAC3 D to analyze the stability of GRS retaining wall under influences of various factors.Studies have shown that,the inner friction angle and cohesive strength of the filler and the inner friction angle between reinforcement and soil have significant effects on the stability of GRS retaining wall,while the tensile strength of the reinforcement strip,the cohesion between the reinforcement and soil,the nature of contact surface between the panel and the filler and the contact between the panel and reinforcement strip have a subtle effect which can be ignored.The difference of GRS retaining wall safety factors with whether the panel or not is much less.For GRS retaining wall,because of reinforcement spacing reduction,the reinforcement-soil mutual inhibition effect is more prominent,and there is no need to use traditional heavy panel to limit the lateral deformation of fill soil with good stability of reinforcement itself.3)Experimenting GRS retaining walls based on different foundations by geosynthetics centrifuge model tests,and observing the overall deformation destruction of each model.The results have shown that,the stability of GRS retaining wall on the soft soil foundation or rigid foundation is very good.Without internal destruction of reinforced soil,the destruction of GRS retaining wall is slippage which occurs along the end of reinforced material that is,external damage.On a rigid foundation,the lateral displacement of GRS retaining wall is only about one-tenth as long as retaining wall with a 0.4m reinforced distance.On a soft soil foundation,the maximum lateral displacement of retaining wall with a 0.2m reinforced distance is only about one-hundredth as long as retaining wall with a 0.5m reinforced distance.indicating that the GRS retaining wall has a more significant effect on inhibiting lateral deformation than conventional reinforced soil retaining wall.On a rigid foundation and a soft soil foundation,the horizontal soil pressures at the panel of GRS retaining walls appear to nonlinear changes,and the pressures are light.As a result,there is no need for traditional heavy panel to resist lateral pressures of soil filler.4)Designing typical GRS structure broadening embankment engineering by using of a limit analysis by finite element method,and analyzing the effects of fillers' nature and reinforcement length on the horizontal displacement of the GRS structure broadening embankment.It is recommended that the priority should be given to the selection of well-graded gravel type soil for the fillers,and the internal friction angle is not less than 33 °.The reinforcement length value of GRS broaden embankment is generally from 0.3H to 0.6H(H refers to the height of retaining wall).