Study On Behavior Of Plastic Concrete Cutoff Wall In Deepwater High Earth-rock Cofferdam

Cofferdam is one of the important temporary structures during the process of a watercontrol project for the construction, with the safety of its structure relating to theconstruction diversion, affecting the safety of the project’s main body and theconstruction progress, and even affecting the safety of lower reaches. With theconstruction of some large hydraulic projects, the scale of the cofferdam is increasing,which leads to increasing difficulties of construction. Therefore, the stability analysis ofstructure for cofferdam is becoming more and more important.The concrete cutoff wall of the cofferdam is one of the main type of seepage control.Engineering practice shows that there exist some disadvantages of the general rigidconcrete cutoff walls, of which the wall is easy to crack because of its high elasticmodulus and small limit strain which reduces the anti-seepage effect and affects thesystem security of the cofferdam. In recent years, the study found that the permeabilitycoefficient of plastic concrete is smaller, the elastic modulus were lower, which can welladapt to the deformation of the surrounding soils. Therefore it has been widely used inmany temporary cofferdam of projects, and have achieved good results.Based on the national “Eleventh Five-Year” Technology Support Project, this paperstudies the plastic concrete cutoff wall in deepwater high earth-rock cofferdam, using thefinite element analysis software of ABAQUS as a large calculation tool, the researchworks as follows:(1)The cofferdam body and the constitutive relations of cutoff wall materials arediscussed, some commonly used constitutive model are analyzed, and constitutiverelation which can reflect the working characteristics of plastic concrete anti-seepagewall and cofferdam filleris put forward.(2)By using the finite element software ABAQUS, through the procedure interface,Duncan-zhang model in finite element software is realized.(3)Wudongde cofferdam project is studied by using numerical simulation, and theworkability state of cofferdam and cutoff wall in the construction process is analyzed.(4) Various factors affecting the workability state of the cutoff wall, including theoperating water level, overburden thickness, cofferdam filler, overburden materials,impervious material, the contact surface characteristics, material anisotropy and wetdeformation are studied. This thesis is divided into six chapters: in the first chapter, the scientific significanceof the subject, the application prospects, domestic and international status, currentproblems and the main work are explained; in the second chapter, some basic knowledgeof the plastic concrete, the cofferdam and the constitutive model of the cutoff wall areintroduced; in the third chapter, the finite element analysis of the plastic concrete cutoffwall is studied; in the fourth chapter, Wudongde Cofferdam Projectis taken as an exampleto analyze stress and deformation of plastic concrete cutoff wall of deep water highearth-rock cofferdam; in the fifth chapter, the factors that affect the workability state ofthe cutoff wall are analyzed; in the sixth chapter, some conclusions and outlook of the fulltext are made.