Research On Vacuum Combined Surcharge Preloading Strengthen Soft-foundation And Border's Effect

Vacuum combined surcharge preloading is a new generation of soft reinforcement effective method developed from the vacuum drainage surcharging method and conventional drainage surcharging surcharge method. At present, The research of vacuum combined surcharge preloading research is mostly in the area within the reinforcement, but the studies of border areas outside the region is lack, that restricts the further development and engineering applications, and so in the vacuum combined surcharge preloading theory and engineering practice on the basis of extensive research, engineering and academia to address the main problem with the vacuum combined surcharge preloading consolidation reinforcement of the soft ground, the border effect, border stability, and border problem prevention measures research, mainly on the following aspects:(1) Taking full advantage of the site monitoring data, I analysis the law and mutual relations of vacuum, surface subsidence, deep stratified settlement, pore water pressure, deep horizontal displacement in the process of drawing vacuum and drawing vacuum combined surcharge preloading, and further study the relationship of surface subsidence, the pore water pressure, the deep horizontal displacement with positive and negative pressure loads and time.(2) Sum up the analytical solution of consolidation theory in negative pressure conditions and deduce the difference solution of consolidation theory in negative pressure conditions based on Terzaghi theory consolidation, Then, with vacuum surcharging and pre-loading mechanism of reinforcement, explains the mechanism of vacuum combined surcharge preloading soft-reinforcement, last make use of surface subsidence, pore water pressure, layer settlement impute consolidation degree, and that the settlement and the layered surface subsidence have different projections moment of the consolidation of the pore water pressure than projections based on the degree of consolidation must be large, reason of this problem is surface subsidence, and the pore water pressure test stratified settlement means different in part(3) Referring to study the border boundary effect and influence factors and border stability of vacuum combined surcharge preloading, first boundary effect and influencing factors were analyzed, and then limit equilibrium method based on the basic theory, introduced in a number of established the stability on the basis of its analysis methods, such as Sweden arc, Bishop, Janbu, Morgenstern-Price law, and stability of the border. Finally, the combination of engineering example, using the above methods, conducted by GEO-SLOPE stability of the simulation analysis, the safety factor are obtained greater than one, slope stability.(4) Construction technology of vacuum combined surcharge preloading has now basically ripe, but still need to be further improved and the sand cushion and the improvement of drainage pipes, employs variable vacuum energy method, without vacuum sealing membrane combined surcharge preloading pressure, composite geomembrane improvements. On the border problem, the release of stress can be taken digging trenches, clay filling and fighting for cement mixing pile tent or steel sheet pile, optimizing reinforcement areas such as prevention and treatment measures shape.