Nonlinear finite element analysis of soil-culvert interaction
Abstract
A finite element based methodology has been developed for the analysis of soil-culvert interaction. An elastic plastic work hardening cap soil model and a large deformation formulation are included in the computer program. The possibility of yielding of the culvert is accounted for by using a Von Mises yield criterion. The compaction and construction processes are also simulated. Predictions with this program agreed with the results of field, laboratory, and full scale tests. The use of an elastic-plastic cap model improved the analytical predictions and enhanced the simulation of compaction loads. The compaction loads were found to significantly increase the deflection and bending moment in the culvert. For an 18-gauge $2{2\over3}$ x ${1\over2}$ corrugated steel culvert with a diameter of 10 ft, the weight of the compaction equipment should not exceed 2000 lb, and the distance between the compaction equipment and the culvert should not be less than 1.5 ft. Bending stresses are of the same order of magnitude as the thrust stresses and they significantly contribute to the yielding of the culvert. Prime locations for yielding of the culvert are at the spring line and shoulders; the crown was identified as the potential location for snap through buckling; shear failure develops in the soil in the neighborhood of the spring line and above the upper half of the culvert. Yielding of the culvert, soil shear failure, and large buckling deformation (individually or combined) were identified as the causes of failure of soil-culvert systems. The performance limit of soil-culvert system can be increased by increased degree of soil compaction, height of soil cover above the crown, and yielding resistance of the culvert. Minimum soil coverage of 4 to 6 ft above the crown are required to protect flexible buried culverts from failure under the influence of heavy live loads. All the current closed-form buckling theories gave conservative results when compared to finite element analysis because these theories neglect part of the soil support. The finite element stability analysis showed that including soil support leads to an increase in the critical failure pressures.
Degree
Ph.D.
Advisors
Chameau, Purdue University.
Subject Area
Civil engineering
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