Simulation And Analysis On Settlement Process Of Typical Soft Foundation Treatment For Highway Construction For Sichuan Basin

There are many chicken terrain in Sichuan Basin, ridge and valley alternate, roads are excavation Cutting and fill embankment length with tens of meters to more than one hundred meters of the small pieces alternate appear frequently. Perennial drain difficultly within the valley, the soil is mostly saturated, high water content, low strength, compression large, for the higher embankment section, it would be soft ground. The soft ground in basin is not thick, usually 7～10m, hardly any more tan 10m, the height of embankment is 8 to 15 meters, a small number of embankment height is up to 20 to 30 meters.The most extensive and effective soft foundation treatment methods that be used in highway construction in Sichuan Basin are soft plastic drain and gravel pile, this paper select Dazhou-Chongqing expressway k26 +283 tender for the typical operating point, simulate the settlement of the operating point through finite difference software engineering of FLAC3D, and compared with field monitoring data, proved the reliability of simulation on settlement process for Sichuan Basin with FLAC3D. In order to compare the effect of the two methods of treatment, This paper used the physical and mechanical index of Dazhou-Chongqing expressway, established models that the embankment height are 5m,10m,15m and 20m, simulate the settlement process. Mainly obtained the following conclusions:(1) The results of typical operating point simulation are similar to the monitoring data, it shows that the method of using FLAC3D to simulate the settlement process of Sichuan Basin is reasonable.(2) The ultimate settlement of the plastic drain treated foundation and the untreated foundation is equal, but the settlement speed of the plastic drain treated foundation is much faster than that of the untreated foundation, and the residual settlement of the plastic drain treated foundation is smaller than that of the untreated foundation, the construction period of the plastic drain treated foundation is shorter than that of the untreated foundation.(3) Plastic drain and gravel pile are both suitable to Sichuan Basin, they both can decrease the residual settlement and shorten the construction period. The ultimate settlement of the gravel pile treated foundation is much smaller than that of the plastic drain treated foundation, and the construction period of the gravel pile treated foundation is much shorter than that of the plastic drain treated foundation, but the cost of the gravel pile is much bigger than that of the plastic drain, so when the construction period is long, it better to choose the plastic drain, when the construction period is short, it better to choose the gravel pile.