| In order to develop and utilize the tidal flat resources in coastal areas,it can be turned into large-scale construction land by means of land reclamation.However,the dredger soil formed by this technology often has the characteristics of large natural water content,large plasticity index,large porosity ratio,small weight,high compressibility,low permeability,etc.It needs to be treated before it can be used as the foundation of a building.In order to further understand the soil properties,consolidation characteristics and consolidation mechanism of the dredger fill foundation,this paper uses indoor and outdoor tests and numerical analysis methods to conduct numerical simulation and analysis of the vacuum-heap combined pre-load consolidation of the dredger fill foundation,The consolidation theory of large deformation and small deformation calculates the distribution law of settlement,horizontal displacement and ultra-static pore water pressure of dredger soil,and analyzes its consolidation characteristics.The main research work and content are as follows:(1)Conduct indoor and outdoor tests and tests on dredger soil samples to obtain the basic physical and mechanical property index values of the dredger soil and perform statistical analysis to obtain the correlation between the dredger soil properties;the principle of least squares is used Fitting and analyzing the regression formula of soil property index.(2)Through the indoor one-dimensional consolidation test,the relationship between the porosity and time at various levels of pressure and the relationship between the porosity and the consolidation pressure are obtained.The preliminary consolidation pressure,primary consolidation completion time,secondary consolidation coefficient,Compression index and other consolidation characteristics and compressibility indexes of dredger soil were analyzed,and the primary and secondary consolidation characteristics of dredger soil were analyzed.(3)A brief description of the soil constitutive models commonly used in geotechnical engineering,summarizing the basic principles of the revised Cambridge model and the precautions for the application of Abaqus software.When the finite element analysis model is established,the life load of the unit is realized by editing the keywords to implement the application of the heap load;the user subroutine is written in Fortran language to realize the change law of the initial void ratio of the fill with the depth of the formation,so that the numerical model is closer to the actual situation.(4)Abaqus software was used to simulate and analyze the consolidation and settlement characteristics of the dredger fill under vacuum-heap loading combined preloading.The results show that the settlement,horizontal displacement and ultra-static pore water pressure of the foundation calculated by the large and small deformation theory are consistent with the change trend of the measured result,and the calculated result by the large deformation theory is closer to the actual measured value,which verifies the it is feasible to convert the plastic drainage board into a sand wall for calculation.In the vacuum preloading and vacuum-stacking preloading phases,the soil in the reinforced area mainly produces shrinkage deformation,while the soil outside the reinforced area produces shear deformation and uplift that shrink vertically and extend horizontally,respectively.The well resistance effect has a great influence on the dissipation of the super-static pore water pressure of the soil in the reinforced area.The application of ground loading will cause a significant Mandel effect in the distribution of the super-static pore water pressure in the soil outside the range of the plastic drainage plate.(5)Based on the large deformation theory,the Abaqus software was used to analyze the deformation characteristics of the dredger fill foundation under vacuum-stacking combined preload,and the ground stacking size,vacuum under the membrane,and plastic drainage board design were discussed.The influence of parameters such as depth,foundation Poisson's ratio and expansion coefficient on the deformation characteristics and reinforcement effect of the vacuum-heaping combined preloading treatment of the filled foundation. |
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