The Dynamic Characteristics Research Of Geosynthetic Materials Reinforced Soil Under Cyclic Loading

With the rapid development of economy, the large increase of highway traffic flow andload capacity of automobiles, and the faster speed of vehicles, Put forward higher standards oftraffic engineering, there are higher requirements for safety, comfort and durability ofhighway engineering structure. The traffic load is a kind of dynamic load. Under thelong-term effects of the cyclic loading, the bearing capacity and settlement ofembankment can not be ignored, It is the premise of design work. At present, the design ofhighway structure in the world standards of highway engineering is mostly researchedaccording to the theory under the static load, however, the actual action on the highwaystructure in the process of vehicle driving is random variation and far more bad and complexthan considering the action of static load. Therefore,the dynamic characteristics of highwaystructure under the traffic loads has become a hot research topic. In recent years, thereinforced soil technology of geosynthetics has been widely used in highway construction,The application of the technology improves the mechanical properties of road structure, Butthe reinforcement-soil interaction mechanism under dynamic loading is quite complicatedand its theoretical research level is far behind the actual engineering application. To this end,researching the dynamic characteristics and deformation nature of soil and reinforced soil inthe action of cyclic load, establishing scientific and reasonable quantitative or qualitativetheoretical calculation and numerical analysis method to improve the level of road structuredesign and analysis, which has important theoretical significance and engineering applicationvalue.This paper, through the dynamic triaxial test and numerical simulation analysis, thedynamic characteristics and deformation nature of soil and reinforced soil under the action ofcyclic load are researched. The main content of the paper and the conclusion is as follows:(1) Through the study on mechanical characteristics and application of geosyntheticreinforced soil materials, summarize reinforcement mechanism and dynamic characteristics ofthe geosynthetic materials of embankment under traffic load, in order to make a theoreticalpreparation for the further research of reinforced soil dynamic characteristics.(2) Through the soil and reinforced soil dynamic triaxial test, clay and silt and thedynamic performance of the reinforced soil under circulating load is studied, get the law ofdynamic elasticity modulus and damping characteristics parameters changing with theamplitude of dynamic strain; By taking different confining pressure (50Kpa,100Kpa and200Kpa), different reinforcement layer (0layer,1layer and2layers) the dynamic triaxial test to get the change rule and influence factors of dynamic modulus of elasticity and dampingcharacteristics. The test results analysis: the dynamic elasticity modulus of soil and reinforcedsoil presents a trend of attenuation with the increasing of dynamic strain and increases withthe increasing of the confining pressure, but the Reinforcement effect have Less affected bythe dynamic elasticity modulus; the damping ratio increases with the increasing of dynamicstrain and has a tendency to decrease with the increasing of confining pressure, the reinforcinghas a significant influence on the damping ratio of the filling, with the increasing ofreinforcing layers, the damping ratio also increase accordingly.(3) The dynamic triaxial test results of clay and silt are compared and analyzed. Theresults show that when the strain is small, under the same dynamic strain, the dynamicelasticity modulus of silt is higher than that of the clay, while when the dynamic strain εd ismore than0.01, the relation curves of dynamitic elasticity modulus and dynamic strain of thetwo kinds of soil samples tend to be consistent gradually. When the dynamic strain is εd>1×10-3, within the same strain range, the damping ratio of silt is more than that of the clay.(4) Application of the results of dynamic triaxial test to get the dynamicparameter--dynamic elastic modulus Ed and damping ratio λ, By use of ABAQUS finiteelement numerical simulation method to establish the elastic-plastic model and calculatedeformation and analysis of reinforced embankment under circulating loads.