Strenthening Mechanism Of Vacuum-surcharge Preloading And Finite Element Analysis On Large Deformation

There are the wide distribution of soft clay in the coastal region ofsoutheastern,as a result of the soft clay with high compressibility, low strength, lowpermeability and poor characteristics, it is necessary to take measures to deal with softand weak foundation in the highway construction, vacuum-surcharge preloading isone of the many processing method, because the method combine the advantagees ofvacuum preloading and surcharge preloading, it is applied widely, however, a series ofissues about the method have not been unified understanding, like reinforcementmechanism, the variation of groundwater level and so on, and previous studies havefocused on considering the small deformation influence on the consolidation, rarelyconsider the influence of large deformation on the consolidation, the calculated resultis not accurate in many cases and can not satisfy the need of project. So this paper wasbased on the vacuum-surcharge preloading of the subject, combined with "Luqiao toZeguo bridgea section" highway preloading segment, using the finite element methodto analyze it. The main research contents and results is listed below:(1)Through related data collection in the country and abroad, introduces theresearch status of vacuum-surcharge preloading method and related theory, and thetheory on the reinforcement mechanism of vacuum-surcharge preloading were furtherelaborated and summarized, from the analysis of the situation, vacuum-surchargepreloading is better than vacuum or surcharge in strengthening effect.(2)Introduces and summarizes the small deformation theory and the largedeformation theory separately, and expounds the derivation process and finite elementmethod, validated the reliability of the finite element method through a example.(3)By the ABAQUS software, according to the small deformation theory and thelarge deformation theory，meanwhile，the PVDs will be converted into plane sandwall, the consolidation process and the reinforcement effect of vacuum-surchargepreloading on the "Luqiao to Zeguo bridgea section" highway is simulated, and itsconsolidation of settlement is analyzed,the soil of the final settlement, layeredsettlement and horizontal displacement are calculated respectively, the computingresult are compared with measured data. Data analysis shows that,when the soft solifoundation with high compressibility, considering the large deformation finite elementeffect calculation are more consistent with the data.(4)On the large deformation,analysis of the permeability coefficient, the Poisson’s ratio, the prefabricated vertical drains and drainage ability for thestrengthening effect of vacuum-surcharge preloading.