Study On The Mechanism Of High Vacuum Drainage Combined With Dynamic Compaction For Soft Foundation Consolidation

The reinforcement of soft soil foundation is complicated system engineering. It is the key problem for the reinforcement of soft soil and construction control to correctly understand the reinforcement mechanism and effect. In view of the typical geological condition in Wanjiang urban area, it is of important theoretical significance and practical value to select reasonable foundation treatment. In this paper through theoretical mechanism research, field monitoring and numerical simulation, the reinforcement effect was analyzed about the new technology of soft foundation treatment of high vacuum drainage combined with dynamic compaction for soft foundation consolidation in Wanjiang urban area. The main research results are as follows:(1) Site monitoring was conducted by low vacuum preloading of soft reinforcement based on the typical case of project in Wanjiang urban area. Through the field monitoring, including the vacuum degree under film, subgrade settlement, pore water pressure and dynamic compaction acceleration, field monitoring data were obtained and the law of change was analyzed. Finally, the load test was carried out to verify that the characteristic value of subgrade bearing capacity is greater than the value of the design capacity 120kPa.(2) Numerical simulation was carried out by means of vacuum drainage about treatment of soft soil subgrade in Wanjiang urban area. The variation law of the construction scheme was analyzed with the drainage plate of the space 1.1m under the square arrangement, including the distribution of pore water pressure, ground settlement and degree of consolidation with high vacuum drainage. Pore water pressure decreased gradually with the increase of loading vacuum days. Consolidation degree increases gradually in the early stage. With the increase of the depth, the change amount of pore water pressure and the stratum settlement gradually decrease. Besides, the effect of reinforcement was compared and analyzed with the different spaces of plastic drainage plate in the process of high vacuum preloading.(3) Numerical simulation was carried out about treatment of soft soil subgrade by means of the next working procedure-dynamic compaction. The effect of compaction process was also compared and analyzed under the different tamping energy, including the formation and dissipation process of pore water pressure, surface subsidence and ground settlement. The greater energy, the greater excess pore water pressure. In the process of dynamic compaction pore water pressure decreases rapidly in the shallow area, but in the deep area pore water pressure decreases slowly. When the time of dynamic action is the same, the larger tamping energy causes larger surface settlement.(4) The selection of the optimum space of plastic drainage plate and best tamping energy were analyzed in the process of soft foundation treatment. It is of great important theoretical significance and engineering practice value in the actual construction process.