Dissertation
Dissertation > Industrial Technology > Building Science > Soil mechanics,foundation engineering > Foundation > Artificial foundation reinforcement > Shallow and deep mechanical reinforcement ( compaction ) > Preload ( sand wells, heap load )

Vacuum-surcharge Preloading Simulation and Settlement Analysis Based on ABAQUS

Author TuXianHua
Tutor QiuHongSheng
School Wuhan University of Technology
Course Road and Railway Engineering
Keywords vacuum combined with surcharge preloading ABAQUS stimulation subprogram correction factor
CLC TU472.33
Type Master's thesis
Year 2010
Downloads 198
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With the progressing development of transportation industry, daily enhanced densities of railroad and highway network, as well as the reclamation engineering grew up in coastal port cities, there are more and more large civil programs constructed on soft soil foundations. Consequently, more and more attentions have been paid to the treatments of soft soil foundations. Constructing buildings on foundations of soft soil will cause big and uneven settlements. Also, because of theological property of the soft soil, there will be bigger post-construction settlements and longer durations. In resent years, the vacuum-surcharge preloading method is widely applied in treating soft soil. This method combines the advantages of vacuum preloading and preloading method and shortens the cycle of consolidation. Since it is more effective to consolidate, it is fit for consolidation of large area of soft soil and has obvious economical benefits. However, due to the complexity of soft soil and differences of boundary conditions, the researches of settlement and the mechanism of the vacuum combined with surcharge preloading are far behind the engineering applications. At the present stage many programs are designed and constructed based on existing experience, which often lead to quite big differences between the predicting outcomes and the experimental results. Consequently, the deep deviling into this area is significantly helpful.Although there have been ceaselessly forgoing studies on the mechanism of the vacuum combined with surcharge preloading, there is no unified theory about it, which would be a significant disadvantage for guiding the designing and constructing of engineering. Thereupon, based on the forgoing studies, this paper makes a further probe into the mechanism of the vacuum combined with surcharge preloading.As shown by many documents, the former simulation analysis of vacuum combined with surcharge preloading is often equated to those of preloading by translating the vacuum loads into the preloads. Yet, these two loads are constitutionally different in the action effects. During the simulating calculations, translating the vacuum loads into the preloads often leads to a too rapid sedimentation rate and a very large consolidation deformation, and even calculation results which are not convergent. Therefore, by using the ABAQUS software, the process of the vacuum combined with surcharge preloading was simulated and its computation of settlement has also been analyzed. During the simulation, the vacuum degree was directly simulated rather than be translated into preloads. Different from the traditional equivalent conversion from plastic drainage board into shingletrap, by using the second development platform offered by ABAQUS, this paper compiles UEL subprogram of plastic drainage board element. In this subprogram, axial forces and effects on the whole penetrating qualities, rather than self weights as well as the drain boards’ shear and torsion capacities, are considered significantly. Through the simulation of the 322 area of reclamation program in Tianjin, and comparative analysis with the experimental results, the paper’s simulation analysis is proved out to be feasible and right, and the UEL subprogram is also feasible.Finally, the ultimate settlements of the vacuum combined with surcharge preloading under different Poisson ratios and reinforced ranges were separately computed. Through analyzing these calculation results the correction factor of settlement according to a Poisson ratio and a reinforced range was obtained ultimately.

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