| At present, the phenomenon of differential settlement of roadbed is widespread in highway construction in China. Since the damage of roadbed is inconvenient to the destruction of maintenance and repair, maintenance and repair costs a lot. These phenomena show various degrees in Jiangxi and Hunan provinces. These problems will inevitably lead to serious economical loss in highway construction, for example, maintenance costs, investment waste and adverse social impacts, if they can not be settled by economic and effective measures.In this paper, through research, theoretical analysis, to combine laboratory test, Geotechnical centrifuge modeling test with field test aims to approach the theoretical study and solve practical engineering problems by cross-disciplinary approaches of prestrained technology in concrete engineering and collision theory. Namely, on the basis of extensive research, there is a comparative analysis on a series of issues the current embankment, such as, the stability and non-uniform settlement. With the helping of laboratory testing, on-site observation and theoretical analysis, around prestrained reinforcement engineering and dynamic compaction, combining lately advanced new technologies with methods of application of research, science, this paper systematically puts forward roadbed stability and settlement control of non-uniform effective method. It has a certain significance to improve the roadbed of the working conditions, the using performance of the road.Geosynthetics for its lightweight, durable, and practical characteristics in the form of reinforced soil is widely used in geotechnical engineering. Use of geosynthetic reinforcement of high filling embankment can shorten the construction period, reduce costs, improve the stability of the roadbed and the effective extension of its service life. However, geosynthetics has been placed in soil whether its the long-term changes in mechanical properties affects on solid projects stability, that concerns a lot all of us. Based on the creep experiments for geosynthetics, the creep characteristics of Netlon CE131geonet.SDL25geogrid and their influenc factors are studied for two years. Meanwhile, the mechanism of creep for Netlon CE131geonet.SDL25geogrid from occurring to be destroyed is studied too. Based on the experiments, the creep formula ε(t)=(σc/E)+(σc t/η)(in this formula σc is the stress level) for the CE131.SDL25is obtained. For the Netlon CE131geonet, when exterior load is larger than60%of the ultimate tensile strength and the temperature is higher than25℃the creep of Netlon CE131is affected apparently by the change of the temperature. And it is no longer affected by the temperature when stress level is below40%or the temperature is lower than25℃.Because lode of SDL25is not more than40%,the creep characteristics of SDL25is hardly affected. Meanwhile, the calculation model to estimate the prestrained value is also put forward (εi=△εi’+△εci+△εri’); It is important referencial value for prestrained reinforcement engineering.In order to popularize prestrained reforcement engineering, a new design thinking and construction technology are put forward. Reverse arch of concrete is applied to prestrained reforcement engineering of bed at first, a new count formula on revrese arch are put forward too, newly revrese arch δi=K0αLi(εti)0.5/2.Further confirmed by numerical analysis, soil modulus and tensile modulus of reinforcement between the different match, there is a direct impact on the stability of reinforced effect. Different soil elastic modulus reinforced slopes, a range of reinforcement tensile modulus matching to reinforcement should be chosen. A high tensile modulus of reinforcemen is used for the high elastic modulus of soil slope so that the role of reinforcement and soil is relatively more desirable properties.The micro-stress of geogrid in the reinforced soil unit is related to the tensile strength of geogrid, reinforced layer spacing, soil properties and time; When the macro-stress of reinforced soil unit unchanging, the stress relaxation of geogrid would lead to the gradually decrease of micro stress of geogrid unit and gradually increase of micro stress of soil unit, and the micro stress of unit wouldn’t tend to stable until the time of Tp while the reinforced soil arrived plastic state; The effect of model parameters of geogrid and the defqrmation and strength parameters of soil on Tp have different degrees. Based on different hypotheses, this paper analyzes the interaction between the reinforced earth and the mechanism of reinforced earth is reasonably explained; from the analysis of micro-stress of geogrid in the reinforced soil unit based on macro the reinforced soil unit, constitutive model of reinforced soil is established based on geogrid viscoelasticity in order to provide the scientific theory for reinforcemen technology.Geotechnical centrifuge modeling is deeply concerned more and more in geotechnical engineering because it is regarded as the test of revealing soil’s true features. According to modern theory of relativity on the absolute equivalence of gravity and the principle of inertia, so that1/n scale model of the geotechnical centrifuge acceleration field in the run, and to ensure that model and the prototype of the stress and strain are equal, the deformation is similar to the same failure mechanism, the prototype representation Deformation characteristics. This model by n=30for Geogrid Scale Flexible bridge model test, once again reveals the geosynthetic material can effectively limit the lateral displacement of soil to prevent the generation of micro-cracks, thus improving the stability of the roadbed.In recent years, with the rapid development of highway, the problem of improving compaction quality and decreasing post-construction settlement of embankment should be solved quickly. Dynamic compaction has been adopted to improve embankment for its wide adaptation to the soils, remarkable effects, economic building materials, low cost and short construction period etc,. However, some problems in the reinforcement mechanism and design theory still exist. Due to the shortage of the standard of design and theoretical basis of dynamic compaction, and the design of its construction parameters has been experiential(without practice) and confused. In the case, it has to be determined by means of small scope tests, so the result for the architects acts blindly and randomly. Putting the dynamic compaction into construction, crushed-stone embankment is improved by dynamic compaction is systematically studied in this paper. Considering the characteristics of imperfect elastic collision and the theory of dynamic foundation in half space, vibration equilibrant equation of hammer is established and the process of impact is analyzed. Solutions of impact stress and deformation are also obtained, furthermore, the influence factors and orderliness of impact stress and deformation are researched in theoretically. The paper determines the parameters of dynamic compaction and analyzes the strengening effect and deformation orderliness via a novelty in-situ experiment. The numerical simulation of whole dynamic process is carried out and the contours of displacement&stress are obtained with explicit dynamic finite element program Ansys/Ls-dyna. The results show that the orderliness of stress&strain are quite consistent with the experiment results and theoretical analysis results.At the same time, the prediction precision of kinds of predicting models on roadbed settlement is researched, and it can be drawn that hyperbola and index curver are more suitable for the prediction in middle period about half a year. Pearl curve、gray prediction、 Gompertz curve method and Pearl-neural network are more suitable for the long-period about a year; moreover, Pearl-neural network is the highest precision in four prediction methods, and the precision of GM(1,1) predicting model is the highest. |
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