| With the advancement of urbanization in coastal regions,coastal land resources problem has always been a major problem hindering the development of the urbanization,covers an area of large coastal tidal flats and is more common coastal city land resources,but the tidal flats foundation with low strength,large amount of compression and moisture content is large,and many other adverse factors cannot be directly used for urban construction.How to strengthen the strength of tidal flat foundation for construction has become an important problem in coastal urban development.On this basis,this thesis proposes the method of flocculation vacuum preloading combined with electroosmosis to strengthen the coastal tidal flat soil,and studies the time point of electroosmosis intervention,zonal flocculation,step by step pressure and other factors.The main contents are as follows:(1)Conduct flocculation and sedimentation tests on three kinds of organic flocculants,APAM,CPAM and NPAM,and evaluate the flocculation and dehydration effect of the flocculant by observing the sedimentation of the slurry and water separation surface in the test process,so as to determine the best flocculant dosage.At the same time,the acid and alkaline conditioning is carried out to determine the best amount of flocculant in the acid and alkaline conditions of the mudflat soil.(2)The indoor model test of flocculation-vacuum preloading combined electroosmosis consolidation of soft soil in tidal flat was carried out,and the study was carried out according to different electroosmosis intervention time.The electroosmosis was carried out after 0h,14 h and 36 h of the test,respectively.The displacement,pore water pressure,water content,shear strength and bearing capacity of the cross plate in the three groups of tests were analyzed to evaluate the reinforcement effect of the combined method of electroosmosis,flocculation and vacuum preloading,and to determine the optimal intervention time of the combined method of electroosmosis.(3)According to the characteristics of different optimal flocculant dosage in the soft soil of tidal flat under acid and alkaline conditions,the flocculation part is improved on the basis of the optimal electroosmosis intervention time.The zoned flocculation-vacuum combined method of electroosmosis-zoned flocculation-vacuum is proposed to strengthen the soft soil foundation of tidal flat,and the laboratory test is carried out.The indexes of the soil after reinforcement were compared with those of the electroosmosis-flocculation-vacuum combined method,and the reinforcement effect of the electroosmosis-zoned flocculation-vacuum combined method was evaluated.(4)In order to solve the problems of soil moisture content and uneven distribution of shear strength of cross plate,the power-on mode was improved based on the combined method of electroosmosis,zoned flocculation and vacuum,and the power-on mode of step-by step pressure was proposed.Four stepwise pressure potential gradiens of 1.0V /cm(control group),1.0-1.5V /cm,0.5-1.0-1.5V /cm and 0.3-0.6-0.9-1.2-1.5V /cm were selected to compare and analyze the reinforcement effect of each group,and the best stepwise pressure gradient was determined. |
PDF Full Text Request