Response Analysis Of Diaphragm Wall With The Influence Of Vehicle Load

With the development of society, traffic volume and vehicle loads grow rapidly and the overloading phenomenon occurs frequently, so the influence of vehicle loads on the deformation and stability of foundation pit are increasingly marked. At present,there has not formed consistent conclusion on this issue that how the vehicle loads affect the excavation supporting structures in the design of foundation pit. Aiming at the problem that how to consider the effect of vehicle loads and whether or not to consider the dynamic characteristics of vehicle loads, based on the conventional theory considering the effect of vehicle loads and vehicle load models, the dynamic load of vehicle loads is deduced and the conventional equivalent thickness of soil layer method is improved to analyze the effect of vehicle loads.Based on the project with diaphragm wall supporting structure, the simple harmonic load is adopted to reflect the dynamic characteristics of vehicle loads when the effect of vehicle loads on the diaphragm wall is analyzed. The results provide preferences for the design and improvement of diaphragm wall with the influence of vehicle loads.Aiming at the problem that how to consider the dynamic vehicle loads induced by the road roughness, the road shape is simplified as harmonic curve, and based on the relationship between the dynamic vehicle load and the road roughness, by considering the influence of velocity, mass, geometric stiffness and damping, two-degrees of freedom quarter-truck model is introduced to simplify the vehicles, and the vertical acceleration is obtained and the motion differential equations of two-degrees of freedom forced vibration system is established. The calculation formula of the dynamic vehicle load is deduced by solving the motion differential equations and is introduced to establish the load model. The results provide references for the study on the influence of vehicle load on the diaphragm wall.Aiming at the problem that when the conventional equivalent thickness of soil layermethod is utilized to simplify the vehicle loads as the equivalent soil layer in the design of underground excavation-supporting structure, the change of rupture angle caused by vehicle loads is not taken into account. Following Coulomb's earth pressure theory, the deadweight of the active wedge is calculated. Combined with the active wedge equilibrium relation, a convergence value of the rupture angle is calculated by iteration on an equations developed with differential calculus. Then the total vehicle loads consist of the static and dynamic vehicle loads are represented by an equivalent soil layer with a specific thickness. It provides preferences for the stability analysis of diaphragm wall with the influence of vehicle loads by improving the conventional equivalent thickness of soil layer method.Based on the foundation pit engineering of metro station, the response of diaphragm wall with the influence of vehicle loads is analyzed by introducing the simple harmonic load to simplify the vehicle loads with finite difference software FLAC3 D.The horizontal deformation of diaphragm wall and the displacement of road nearby the foundation pit are analyzed with the influence of different velocities, and the results show that the influence of velocity on the effect of vehicle load is limited and with the increase of velocity, the change of vehicle load is small. The deformation and force condition of diaphragm wall are studied, and on the basis of guaranteeing the stability of foundation pit and deformation standard, it's concluded that the thickness of diaphragm wall changing around 0.6m-1.0m is appropriate and when the ratio of embedded depth to excavation depth changes in the range of 0.6-1.0, the foundation pit is relatively safe and economical. A comparative analysis of the stability of foundation pit is carried out among the three methods of the actual simplified method in project, the conventional equivalent thickness of soil layer method and the improved method,and it's concluded that improved equivalent soil layer method can effectively solve the problem that the soil rupture angle will change with the influence of vehicle loads.