The Monitoring, Numerical Simulation And Forecast Settlement In Soft Clay Foundation Consolidated By Vacuum-Surcharge Preloading

The method of vacuum-charge preloading is used to consolidate the Soft-soil foundation, and it has so many tremendous merits. This method is applied widely with the development of our country’s economic construction. In recent years, it has made great progress in mechanism, processing and design theory. But the theoretical research is backward compared with engineering practice. Quite a few theoretical and practical problems that need further research and improvement, such as:the improved depth, the variation of underground water and the negative impact on environment. In the settlement calculation of soft-soil foundation consolidated by vacuum-charge preloading, most of the effect of vacuum preloading is simply equal to vertical pressure of same preloading, and then calculate settlement by layer-wise summation method. Vacuum preloading and charge preloading both have substantially distinction in strengthening mechanics. After the infrastructure putting into operation, occurs large post-construction or losing stability very possibly. Through the data collected from the indoor and field experiment, this paper discussed the consolidation principle of vacuum-charge preloading. According to the engineering practice, the method of vacuum-charge preloading was simulated by FLAC. And combining of the practical monitoring settlement data, and put forward a new model can well predict soft soil settlement consolidated by vacuum-charge preloading. We have the following main conclusions:(1) Review the current research status of vacuum preloading method and preloading method, and on the basis of this review, made a deep analysis of reinforcement mechanism by Terzaghi’s effective stress law.(2) Through to the analysis of vacuum degree, vertical displacement, horizontal displacement and pore pressure, can conclude that vacuum preloading not only to within10m layers have reinforcement effect. In fact, when the vertical row deep enough water, limit depth should in about20m.(3) Using the FDM code-FLAC3D, the vacuum-charge preloading is simulated. The vacuum has been applied to the soft soil by linear. The practical calculating results shows that calculated data are basically consistent with the practically measured results, for example foundation settlement, pore water pressure, x-displacement, etc.(4) In the existing prediction post-construction settlement and whole process based on settlement method, combining of the practical monitoring settlement, the method for the comprehensive evaluation, and proposes a kind of can well predict vacuum preloading joint under ground settlement of the new method. Compared with other methods, new forecasting model in the prediction precision ground settlement than other methods to high, suitable for combination forecasting vacuum preloading the settlement of foundation.