01551424

Component

Analytical studies have repeatedly shown that soil stiffness plays a dominant role in influencing the structural behavior of buried culverts in loading environments; however, the relative effect of the soil-model formulation (degree of fidelity) has not been systematically investigated. Soil-model formulations typically used for culvert analysis range from simple linear elastic models to fully nonlinear plasticity and variable modulus models. This paper compares the relative influence of three soil-model formulations; linear elasticity (2-parameters), Mohr/Coulomb elastic-perfectly plastic (4-parameters), and the Duncan/Selig variable modulus (8-parameters). After presenting a theoretical review of these soil models, this paper pursues the following pertinent question, “If the parameters for each soil model are fitted to the same set of tri-axial test data, thereby representing the same soil stiffness to the best of each model’s capability, what is the comparative effect on the predicted structural distress of typical buried culverts?” This paper pursues the question in a two-step approach. The first step compares how well each soil model performs in replicating tri-axial test data of granular soil samples that are used to define each model’s parameters. In addition, each soil model’s predictive capability to simulate confined compression experimental data is presented. The second step compares CANDE finite element solutions showing the influence each soil model has on the structural distress for typical culverts. Specifically, graphical charts show each soil model’s influence on the American Association of State Highway and Transportation Officials (AASHTO) design criteria for corrugated steel, reinforced concrete and plastic pipes under deep burial and HS-20 live load conditions. As expected, the 8-parameter Duncan/Selig soil model exhibits the best performance in replicating the laboratory experimental data and in predicting the blind experimental tests. With regard to the comparative finite element studies, the Mohr/Coulomb plasticity model produces results that are nearly indistinguishable from the linear elastic model because the surrounding soil mass around the culvert does not experience plastic shear failure due to large confining pressures. In contrast, the Duncan/Selig model generally predicts greater distress in all pipe types implying it is more conservative and produces safer culvert designs.

This paper was sponsored by TRB committee AFS40 Subsurface Soil-Structure Interaction.

01550057

15-0560

English

24p

2015

Transportation Research Board 94th Annual Meeting

Digital/other

Figures; References; Tables

Culverts; Finite element method; Linear elasticity; Load factor; Soil mechanics; Soil structure interaction; Stiffness; Structural analysis

Bridges and other structures; Geotechnology; Highways; I24: Design of Bridges and Retaining Walls; I42: Soil Mechanics

Transportation Research Board Annual Meeting 2015 Paper #15-0560

TRIS, TRB, ATRI

Dec 30 2014 12:17PM