Uplift Response of Buried pipes in Saturated Sand Using Finite Element Method

In this research a numerical analysis using PLAXIS program has been carried out to investigate the behavior of buried concrete box culverts different parameters including load types, loading locations, culvert dimensions, underlying soil specifications, and the coefficient of earth pressure- at- rest. For modeling purpose, patch loading of rtuck or military tank has been substituted to an equivalent strip load, and the problem has been analyzed under plane strain with application of linear elastic constitutive model.
The result of numerical analysis showed that load location has a considerable effect on the produced moment and shear amounts in the culvert and the most critical case is under the tank loading. The location of maximum Shear and negative moment (positive in PLAXIS results) is at the corner of box culvert, and the location of maximum Shear and positive moment (negative in PLAXIS results) is at the center of upper and lower slab the box culvert. By increasing the box culverts dimensions, the moment and Shear amount Will be increased Significantly. By increasing the elasticity modulus of underlying Soil, moments Will be increased and Shears Will be decreased. The variation of Poisson’s ratio has a little effect on box culvert behavior in terms of Shear and moment. By increasing the side Soil’s coefficient of earth pressure- at- rest of side, the maximum Shear and negative moment (Positive in PLAXIS results) decreased , and Positive moment (negative in PLAXIS results) increased. Finally, the results of linear elastic model are compared With Mohr- Coulomb model, and a good agreement has been obtained: therefore, Considering the assumption of linear elastic behavior for soil is almost good assumption and the results have a good precision.