Vacuum Preloading Method Is Applied Research In The Road Soft Soil

Vacuum preloading is one of the foundation treatment methodsdeveloped recently. The mechanism and design method of Vacuumpreloading have been studied by domestic and foreign scholars, and manyprogresses are made. However, many problems still exist and need to beanalyzed thoroughly because of the complexity of the soft foundation andthe boundary conditions. For example: the equivalent loads in applying finiteelement method; the range of effect of vacuum preloading in construction;how to get the unloading criterion of vacuum preloading. Based on theproject of soft foundations treatments in highway construction, aboveproblems will be researched in this dissertation to provide the application ofvacuum preloading with the technical support.This dissertation focuses on explaining mechanism of vacuumpreloading and calculation of ultimate settlement. The main content is asfollows:1. Applying the theory of seepage field describes the course of Vacuumpreloading, and the treatments effect of Vacuum preloading is explainedby the combined effect of dewatering preloading and the disappearanceof excess pore water pressure in seepage field, which are coinstantaneousand coupling.2. Vacuum preloading and surcharge preloading are comprehensivecompared in technology, economy, and mechanism.3. Combined with the 4-node isoparametric element and Duncan-Changmodel, Biot consolidation theory is used to calculate the lateraldeformation of foundation and field observation data show that the resultis correct.4. Vacuum load is studied, the equivalent loads of applying Biotconsolidation theory to calculation is analyzed.5. Based on observation data, three points' method, hyperbola method andAsaoka method are used to forecast the ultimate settlements of Yu-anwest road project.6. According to the observation data of Yu-an west road and the unloadingcriterion of surcharge preloading method, unloading criterion of vacuumpreloading is presented, which is based on dual control of the settlement velocity and consolidation degree.