Study On Design Optimization Of Prefabricated Diaphragm Wall Structure

Due to the functional specificity,temporary supporting structures are used in most cases and over-investment will waste labor and materials.Many foundation pit accidents at home and abroad show that the instability of foundation pits often occurs suddenly and is devastating,so the deformation resistance and global stability of supporting structures are very important for the safety of foundation pit works.Insufficient safety capacity designed of supporting structures for foundation pits will give rise to engineering accidents.Therefore,one of core issues for foundation pit works is to properly select and design supporting structures.Existing precast underground continuous wall structures can solve irregular mud inclusion and leakage of precast underground continuous walls,but will lead to simple wall forms,big construction difficultly,difficult treatment of vertical joints of wall sections,and deformation resistance and global stability to be improved.To solve the engineering issues above,a new form of precast underground continuous wall,namely arched slab A structure,was designed.Arched slabs transmit soil pressure to girders,which then transmit the pressure to supporting columns.Compared with other structures,especially the traditional slab structure(plane-bearing structure),this new structure is featured by good global stability,strong deformation resistance,excellent sealing effects,construction cost saving,transportation and construction convenience.Through theoretical analysis,a new form(arched slab A)of precast underground continuous wall is designed with good self-stability,small deformation,reasonable stress distribution,easy manufacturing and construction at scale.Then the finite element analysis software ABAQUS is used to analyze the stress and deformation of different types of underground diaphragm walls under the same engineering conditions.Through theoretical calculation,cracks and deflections are compared for siding structure and straight-plate structure,and the deformation resistance and structural rationality are analyzed.Different forms of precast underground continuous walls are studied by 3D printed rubber wall model test.The wall bearing capacity is studied by cement mortar wall model test.At the same time,the numerical simulation and theoretical calculation results are verified.To further study destruction mode of this new arched slab A structure and work out possible design weaknesses,the model test is conducted after additional load is applied until the structure is destructed,this is called destructive test.The ultimate bearing capacity and failure form of arch plate structure were studied by failure test,and the safety and stability of arch plate structure were verified.The analysis shows that the optimized precast underground continuous wall structure form-arched slab A not only has good global stability,high bearing capacity,strong deformation resistance,good integrity,stable structure at destruction,good ductility,tightly connected adjacent sections,but saves construction cost,facilities transportation and construction.Different from traditional panel structure,arch board A fractal structure,load transfer way according to the board-beam-column load transferring,beam structure damage cracks start to board,failure mechanism and framework structure similar and can be effectively on the basis of concrete structure design principle of calculation and analysis,for prefabricated underground continuous wall further optimization design,provides the basis for improving safety reserve.The paper has 60 pictures,17 tables and 85 references.