Elastic-Plastic FEM Simulation And Analysis On Culvert Construction

The culvert is the works buried under the fillings, which is often used in Hydraulics, communication and city engineering ,etc. The whole procedure of construction includes foundation-pit, the body construction and foundation-pit backfill. In recent years, strengthened constantly with scale of infrastructure construction, culvert structures receive general application. The process of construction was simulated and analyzed by using elastic-plastic FEM procedure programmed by myself and the stress field and displacement field were obtained. These results can be the scientific basis for the future engineering design, construction.During the course of simulation foundation-pit, with improved Mana law to calculate the load to release equivalently to excavate and regard Mohr-Coulomb criterion as yield criterion, the method of foundation-pit excavation layer by layer and step by step was used. The elements were excavated gradually in calculation field and the surface of excavation was made the free surface. At the same time, the law of stress field and displacement field with the depth of excavation were studied. In this way, the final stress field anddisplacement field were obtained and regarded as the initial ones for calculating the foundation-pit backfill. By using of the newly increased backfilling -elements' gravity and the grinding force ,the simulation of construction of body of the culvert and foundation-pit's backfill layer by layer were done and the laws of the backfilling soil's loading and deformation were obtained.Through the simulation culvert construction course by FEM, this characteristic of the relation of non-linear literary compositions of soil body has been fully reflected and soil body being in unload state at during the course of excavating or in load state whiling backfilling was reflected. Finally three influencing factors—slope ^ thickness of backfilling and foundation' modulus—to pressure of culvert were simulated and analyzed.Through excavating simulation, the load was not all to be released while excavating and to be fully released out to some extent only while reaching the certain depth (such as finished in excavation in this dissertation); at the same time the position of the maximum of later displacement will change as what has been excavated the seat, moving gradually to the slope. In backfill, it is analyzed that three main influence factors carry the influence of the soil pressure on the culvert, and the slope of 1:2 for " critical slope " is proposed; under the conditions of three influence factors being considered, the coefficient of soil pressure varied from 0.6 to 1.4. The simulation of the whole construction course by FEM has objectively reflected thestress -, strain of each point in the area and scientific basis for culvert , this kind of design , construction of the structures and important actual meanings have been offered.