Study On Reinforcement Characteristics Of High Moisture Content Dredging Sludge Treated By Vacuum Preloading With Horizontal Straw Drainage

When the traditional vacuum preloading method is used to treat dredged sludge,there are some problems,such as slow drainage rate,long construction period,easy bending of drainage plate,poor reinforcement effect of deep soil,and plastic drainage plate inclusion is difficult to degrade in the foundation,polluting the environment.The horizontal arrangement of the drainage body can effectively avoid the bending of the plate to ensure that the vacuum pressure is transmitted everywhere in the drainage body,and the drainage path of the horizontal drainage body can be shortened with the settlement of the soil.China is rich in straw resources and has not been properly utilized as waste.At the same time,the degradable characteristics of straw can produce a large number of nutrients to improve the ecological function of soil.Therefore,this paper proposes to use the horizontal layout of straw drainage body to carry out the test of vacuum preloading consolidation of high water content dredged silt,and to study the reinforcement characteristics of vacuum preloading treatment of high water content dredged silt with horizontal straw drainage system.Through the indoor model test,the following conclusions are drawn :(1)According to the change law of vacuum degree in the process of vacuum preloading test,the attenuation of vacuum degree in the horizontal straw drainage system is mainly affected by the natural degradation of straw,and the vacuum attenuation is mainly concentrated in the middle and late stage of the test,which has little effect on the rapid consolidation drainage in the early stage of the test.(2)By observing the shape of plastic drainage plate and straw drainage body after the test,it can be seen that the horizontal straw drainage body has better anti-deformation ability,so the horizontal straw drainage body has more advantages in the treatment effect.At the same time,through comparison,the horizontal straw drainage system with double-layer layout has better effect on dredging silt.(3)Through the analysis of the relationship between water content and strength of soil everywhere after the test,the horizontal straw drainage system can utilize the influence of self-weight stress of soil to promote the drainage of pore water in soil,and the effect of treated soil is better than that of horizontal plastic drainage plate.Overall,vacuum preloading technology of horizontal straw drainage effectively improves soil strength,and the soil strength after treatment of double-layer straw drainage system is better.(4)According to the degradation characteristics of straw and the distribution rule of organic matter in soil after the test,the cellulose and hemicellulose components in straw have been reduced after the test.The organic content in soil reaches the maximum near the straw drainage body and decreases with the increase of the distance to the straw drainage body.At the same time,straw degraded,a large number of nutrient elements such as nitrogen,phosphorus and potassium were produced,which promoted plant growth and had good ecological benefits.