An Analysis Of Interaction Between The Existing And The Widened Embankments On Soft Soils

With the rapid development of the economy of China in recent years, the trafficvolume has grown rapidly, and therefore, there is a great need to widen the four-lanehighways which were completed in soft soil area of Southeast China in early time. Thecritical problem of widening expressway on soft soils is how to control the differentialsettlement of the existing and the widened embankments within a reasonable range. Inthis paper, the numerical method is employed to analyze the influence of the wideningtime, soft soil thickness, the widened width and the embankment height on thesettlement of the widened and existing embankments, on the surface stress of thewidened and existing embankments, and on the transversal slope of the existingembankment. Besides, the numerical method is also employed to have a comparativeanalysis of the differences of PVD, stone column, rigid pile controlling the settlement ofthe widened and existing embankments.This paper firstly analyzes the changing regularity between the settlement of theexisting embankment before widening and the lapse of time, and then analyzes theinfluences of widening time, soft soil thickness, and the widened width as well as theembankment height on the settlements of the widened and existing embankment. Theresults of the analysis indicate that the settlement deformation of the existing foundationdevelops rapidly at the early stage of consolidation before widening, then it developsslowly at the late stage, and finally it stabilizes. At the beginning of the finish loading ofthe widened embankment, the widened and existing embankments have a fastsettlement, and later they gradually slow down. Along with the increase of time and thethickness of the soft soil, widened width and the embankment height, the differential settlement of the widened and existing embankments also increases.The widened embankment will change the mechanical state of the existingembankment pavement. And this article also analyzes the influences of the wideningtime, the widening width and soft soil thickness as well as the embankment height onthe stress of the pavement of the widened and existing embankments. After widening,surfaces of both the existing embankment and the new one are subjected to tensile stress.With the increases of time, the pavement stress of the widened and existingembankments decreases, and with the increase of the widening width, soft soil thickness,the embankment height, the pavement stress of the widened and existing embankmentsincreases.The widened embankment will also change the transversal slope of the existingembankment. The results of this article show that before widening, with the increase oftime and the thickness of soft soil, the transversal slope of the existing embankmentincreases. And after widening, with the increase of the thickness of soft soil, thewidening width, the embankment height increases. And with the increase of thewidening time, the transversal slope of the existing embankment first increases, andthen it keeps still and does not change at all.In order to understand the different methods of ground treatment on controlling thesettlement difference of the widened and existing embankments, the paper finallyanalyzes the treatment effect of PVD, stone column, rigid pile in soft soil foundation.Analysis results shows that the treatment effect of rigid pile is the best, then follows thatof the stone column, and that of PVD is the worst. Through the comparison ofmonitoring results with the actual construction of soft soil foundation treatment, thispaper finds that the effect of the method employed to deal with the soft soil is consistentwith the measured results.