Study On Reinforcement Mechanism And Stability Method Of Vacuum Combined Surcharge Preloading

Combination of vacuum preloading and surcharge preloading method, which is widely used in engineering, is one of the effective methods for reinforcement soft clay foundation. However, this method's study in theory gets behind in practice, especially it's shear strength and stability analysis theory need to be developed to guide practice. It is important to deeply analysis this method's reinforcement mechanism and design theory for calculating the soil's shear strength and stability.Firstly, the engineering properties of soft clay was analysised. Throngh deeply study of reinforcement mechanism, the characteristic that soil is consolidated by isotropic consolidation pressure in the preceeding of vacuum preloading has been recommended and the formula of calculating shear sthength has been educed through Mohr Stress Circle. Secondly, this method's phase properties has been pointed out by discussing reinforcement mechanism. At the begining of vacuum, shear strength and stability increase and foundation cann't miss stability, so biggish loading can be bringed to bear. Simultaneity, the negative excess pore water pressure due to vacuum can partially counteracrt to the pore water pressure due to stack, so exorbitant excess pore water pressure cann't come into being while soft clay is stacked rapidly. All of these is in favor of stability. Then based on whole mechanics analysis of soft clay, circular arc method have been developed.Finally, slope stability have ben analysised by finite element method. Saftely factor and instability criterion was studied systemic, so method that is defined by strength reduction finite elements combined with gravity increase. Then based on analytic data, it is elucidated that instability is feasible to be judged by multiplex criterion and displacement change and equivalent plasticity deformation must be considered detailedly.