Study For The Control Of Stability And Settlement In Construction Of Soft Soil Road Bank Treated With Surcharge Preloading And Vertical Drainage Wells

As an effective method of strengthening the soft soil, the surcharge preloading with vertical drainage wells is used widely to treat the soft ground in lots of projects which have strict requirement on post-construction settlement and uneven settlement. Observation of the settlement and stability is the most reliable method that controls the construction speed for ensuring the safety and stability of the embankment and evaluates the effects of surcharge preloading. In this paper, the way to control the deformation and consolidation of soft ground under highway embankment were discussed thoroughly according to large amounts of in-site observation data in Guangwu freeway.The elaborate work involves several aspects as follow:1. Based on the microcosmic analysis of the deformation and stability mechanism of soft soils, the suitability and unsuitability of the in-use construction control index was studied, moreover, the dynamic construction control method which based on the on-site data was set up. This method was used in the construction of road bank of Guangwu freeway and got good effect.2. Summarized several familiar curve which can prognosticate the settlement of the soft soil and the numeration method of corresponding parameter were given, moreover, based on the in-site settlement observation data and the known standard of comparing and choosing among different curve model, a new standard, which aimed at material project, of comparing and choosing the curve model which was best fit for the on-site settlement curve among many settlement prognosticate model was established, and the standard was validate by the on-site data of the project.3. By means of demonstrating theory formula of the instant loading model and the linearity loading model, the improved exponential curve model was discussed. The numeration method of corresponding parameter was given, too.4. According to the theory of the delamination summation and lining elasticity, the evaluation of the effect and factor of surcharge preloading reduce post-construction settlement at the status which the sum of effect cover stress and add-stress exceed pre-consolidate press was studied in theory, moreover, the way to design surcharge preloading midst construction based on on-site data was given. Finally, practical way of the determination of pre-compression period was given and some demonstration were given, too.