Experimental Research On Improving Effect And Lateral Displacement For Vacuum Combined With Surcharge Preloading In Reclaimed Soil

With the construction and development of Wenzhou area,the available land area is less and less.In order to optimize the layout of urban space,Wenzhou government promote the city to the east sea development strategy in the thirteenth five-year plan.Enclose tideland projects become more and more popular.There are many low strength and high water content reclaimed soil in Wenzhou enclose tideland.In order to ensure bearing capacity and consolidation of reclaimed soil,it should been reinforced.In view of the extremely poor engineering characteristics of reclaimed soil,vacuum combined with surcharge preloading is concerned by engineering,because of low cost,environment and effects and more superiority.After decades of development and improvement,this technology has been widely used in soft soil foundation treatment in China.However,the study is lagging behind.This thesis researches the effects and lateral displacement of surcharge loading rate under vacuum combined with surcharge preloading by theoretical analysis,laboratory test and a kind of new lateral displacement measuring equipment.The main works of this thesis are:(1)The indoor model tests have the advantages of controlling surcharge load and time.In order to research the characteristics of reclaimed soil,the indoor model test has been carried out by uniform loading and rate method under vacuum pressure and surcharge load while the vacuum preloading model test has set up.Results indicate that the soft soil foundation in coastal reclamation area can be reinforced by vacuum pressure combined with surcharge load fast and excellently.When loaded at constant speed,vacuum pressure,pore pressure and soil surface subsidence have changed significantly but weakened with the passage of time.The reinforcement effect of soil is also superior to ordinary vacuum preloading method.(2)A kind of new laboratory equipment has developed to measure lateral displacement of soil under vacuum combined with surcharge preloading.The inward lateral displacement tendency of soil under vacuum preloading is verified.The device provides an condition for an indoor test of researching the horizontal displacement of the surrounding soil by vacuum combined with surcharge preloading under unconfined conditions.The device facilitates further study in the direction of lateral displacement of soil.(3)The model tests of vacuum combined with surcharge preloading have been set up under three different surcharge loading rates.Through to the analysis of vacuum degree in thedifferent places of PVDs,surface settlement,pore pressure,lateral placement,water content,cross plate shear strength and straight shear strength,can conclude that the greater the surcharge loading rate,the better the treatment effect,but will cause a greater level of lateral displacement of the soil,easy to make soil shear damage.The optimal surcharge loading rate is to keep the soil in a dynamic equilibrium at the initial position.At the same time,this paper provides some measures to reduce the level of soil lateral displacement for the actual project.