Numerical Simulation And Field Test Research On Concreting And Hoisting Process Of Diaphragm Wall

With the rapid development of the construction of underground space,diaphragm wall,which is often used as an enclosure structure,tends to be longer and larger.However,it is easier to face new problems in the construction process of ultra-large diaphragm wall because of the larger difficulty than the normal one.It is known that the large horizontal deformation of H-steel joint,the break of lug reinforcement caused by the change of sling load during the pouring process,and the hoisting of ultra-large reinforcement cage are all key problems to be solved.This paper,taking the pouring and hoisting construction of work well diaphragm wall of a subway engineering in Wuhan as the background,adopts the method of theoretical analysis and field test to make an indepth study on diaphragm wall construction.The finite element model of diaphragm wall,which can simulate the dynamic pouring process,is established by considering the autogenous shrinkage of the concrete and changes of elastic modulus,adopting the suitable yield criterion to simulate the stone in slurry,and applying bilinear concrete lateral pressure inside H-steel web.Field test is also carried out.Then the horizontal displacement of H-steel and the support reaction force of lifting beams are explored.The results of theoretical analysis and field test are compared and an indepth study on the facts of concrete condensation effect and slurry.The results show that,with influence of concrete condensation effect and slurry weakening effect,the horizontal deformation of the H-steel increases first and then decreases,the total support reaction force of the lifting beams increases first and then decreases;the results of the field test are in accord with the proposed theoretical calculation method.The degrees of 0°,30°,60° from horizontal to vertical are chosen as the basic working conditions of the FEM to simulate the dynamic lifting process of ultra-large-scale diaphragm wall and field test is carried out.Combining the results of both numerical simulation and test,the dynamic effect of lifting is studied and the most unfavourable condition is confirmed.Based on the adopted analytical method,damage analysis and optimization analysis are performed.The results show that,the dynamic effect is obvious during the lifting process,the maximum stress of the longitudinal and transverse truss bars appeares under 30° condition,and the stress near the lifting points is large while the one far away from the lifting points is relatively smaller;optimization for lifting schemes can significantly improve the safety and economy of the construction.