Study On The Application Of Vacuum Combined Load Preloading

As a cost-effective foundation treatment method,the vacuum-surcharge combined preloading method has the advantages of short construction period,low construction cost,and good reinforcement effect,so it is widely used in the processing of soft soil foundations.The current vacuum-surcharge combined preloading method has matured,but theoretical research is still not thorough enough.The study on the settlement of reinforced foundation,the post-construction settlement prediction method,the stability of foundation and the influence of reinforcement on the surrounding environment of the soil are still not perfect.This paper relies on the treatment project of soft soil foundation of a power plant in Guangdong,through analysis of the reinforcement mechanism of the construction method,combined with the on-site monitoring data,using FLAC3 D software to simulate the reinforcement effect,and obtained the simulation settlement calculation result and compared with the measured value.The influence of the different depths of the drainage plate and the degree of vacuum under the membrane on the settlement was analyzed.The environmental impact of the vacuum-surcharge combined preloading on the surrounding soil was analyzed,and solutions were proposed.The main work and conclusions of this paper are as follows:Explained the reinforcement mechanism of vacuum-surcharge combined preloading method,explained it from the macroscopic and microscopic perspectives,and analyzed the differences between the vacuum preloading method and the surcharge preloading method in the reinforcement mechanism and reinforcement characteristics.Starting from the actual construction,the vacuum-surcharge combined preloading method,which combines the two,has the advantages of mature technology,economy and convenience,fast consolidation,and favorable stability to the foundation,which is more conducive to the application of the project.Describes the settlement calculation and prediction methods applicable to vacuum-surcharge combined preloading,including classic layered summation method,curve fitting method and numerical solution method.The selection of the project for the soft foundation treatment of the project is analyzed.Compared with the dynamic compaction,the overloading preloading method and the cement soil mixing pile method,the vacuum heaped load combinedpreloading method is cheap and has little influence on the surrounding soil environment,and the stability of the foundation is guaranteed under the requirement of the construction period and the strengthening effect is better.The scheme of vacuum surcharge preloading is adopted for the project.The FLAC3 D numerical software is used to simulate the vacuum-surcharge combined preloading.The numerical simulation method has little difference between the calculated settlement of the soil and the actual monitoring value.It can simulate the actual construction situation well and can be used for prediction.Late settlement.Different set depths of the drainage board and different degrees of vacuum under the membrane resulted in different settlement of the soil.The simulated calculation results in this paper su ggest that the depth of the 15 m drainage plate and the vacuum degree under the membrane be 80 kPa,and a more cost-effective reinforcement effect can be obtained.Since the vacuum preload causes the soil to move towards the reinforcement zone,and the preloading moves the soil away from the reinforcement zone,it will affect the soil and buildings around the non-reinforcement zone.Excavation can be considered in the reinforcement zone 2 meters away.Deep 3m stress relief ditch,or concrete mixing pile with a depth of 15 m,is set 2m outside the reinforced area,effectively controlling soil deformation around the reinforced area,weakening the environmental impact of vacuum-surcharge combined preloading.