Experimental and numerical study of thick soft ground improved by vacuum-surcharge preloading
1.College of Civil and Transportation Engineering, Hohai University, Nanjing, Jiangsu 210098, China; 2.Geotechnical Engineering Department, Nanjing Hydraulic Research Institute, Nanjing, Jiangsu 210029, China; 3. College of Transpotation Science ＆ Engineering, Nanjing University of Technology, Nanjing, Jiangsu 210009, China)
Abstract：To improve the deep strengthening effect, vacuum surcharge preloading method was applied in expressway to change the form of vertical drainage channel. 150 mm width prefabricated vertical drain(PVD) and 100 mm modified bag sandwell were used respectively as vertical drainage body. The bag sandwell was inserted with 10 m long and 8 mm in diameter plastic small tube. The strengthening efficiencies of the two new drainage bodies for deep soft soil were verified by comparison experiments. The results show that attenuation of vacuum pressure is small in 150 mm width PVD with large settlement in preloading period, while the vacuum pressure transmit depth can be increased in 8 mm diameter plastic tube. Based on modified Cambridge model, the soil rheology and reload deformation characteristics after unload were considered to improve the constitutive soil model, and to propose corresponding finite element calculate method.The actual example validation indicates that the data fine accuracy and regularity of calculate values are consistent with those of test values.
2012, Vol. 33 
