Samrat Raut

ORCID Identifier(s)

0000-0003-0933-0228

Graduation Semester and Year

2020

Language

English

Document Type

Thesis

Degree Name

Master of Science in Civil Engineering

Department

Civil Engineering

First Advisor

Xinbao Yu

Abstract

Corrugated metal pipes (CMPs) are one of the widely used culvert structures in the American highway system. Compared to other types of culverts, CMPs have shorter design life, and many CMP culverts have reached or exceeded their design life. Therefore, renewal or replacement of those CMPs is needed to ensure the safety and service of the highways. Since replacements of these culverts are costly, renewalis less costly and has been on the focus in this decade. Different rehabilitation methods have been proposed by different DOTs and the researchers from open-cut methods to trenchless technology. Since open-cut methods disturb the operation of highways, rehabilitation with trenchless technology has been the preferred method. Several trenchless methods such as slip lining, cured-in-place pipe (CIPP), invert paving, and spray-applied pipe lining have been in existence. Although spray-applied lining has been in practice for several years, only limited research has been conducted to assess the structural capacity of these liners along with studies on the structural contribution of the host CMP. For this reason, a detailed study on the structural capacity gained by rehabilitating CMPs using spray-applied pipe liners (polymeric and cementitious) is undergoing at CUIRE, UTA. In this project, deterioration of CMPs is represented by the removal of an 18” wide piece of invert from the intact CMPs. Control tests were first performed on an intact CMP and an invert removed CMP in a soil box to determine the loss in capacity after invert removal. After completion of the control tests, another set of soil box test were carried on invert removed CMPs repaired with the spray-applied pipe liners (polymeric) with three different thicknesses: 0.25-in., 0.5-in., and 1-in. All the test results and the details of the experiment were performed as a team effort done at the Center for Underground Infrastructure Research and Education (CUIRE). This thesis study presents the finite element analyses of the soil box tests performed at CURIE and the development of calibrated FEM models for future parametric studies. The soil box test procedure and results are first briefly presented, which include the plots of the load-displacement, earth pressure, and strains and were used to validate the FE results. ABAQUS 6.14 FEA software was used to carry out FE analysis. The analysis was implicit and non-linear. A full 3D model was developed to represent the experimental setup. The boundary conditions were defined similarly to the experimental setup. The restriction of the movement of the soil outside the soil-box due to end walls in their respective direction was defined by defining the boundary conditions which restrict the movement of the soil outside the soil-box system. Solid model was used to represent Soil, CMP, and liner; and C3D8R element type was used to define mesh elements. To determine the mesh sensitivity of the model, total energy, load-displacement for soil-CMP, and the Von Mises stress for the CMP were compared. The soil was model as Drucker Prager Model which represents the pressure-dependent soil model while CMP was represented by the non-linear elastic-plastic model. The properties of the liner as reported by Parades (2018) suggested it as a brittle material with a small plastic region. Since the model was implicit, cracking behavior could not be represented through FE model. The crack in the FE model was represented by the plastic strain developed in the liner. As the plastic region of the liner was very small, appearance of the first plastic strain in the FE model was compared with the appearance of the first crack in the test. After the completion of the analysis the results obtained from the FE model were compared with the results from the experiment. The FE model for the intact CMP agreed closely with the test results, as seen in the comparisons of displacements, earth pressure, and bending moment. The FE model of invert cut CMP did not predict the behavior from the test well. There was excessive immediate deformation of soil and CMP during the removal of invert in the test, which could not be predicted by the FE model. While for the rehabilitated CMPs, the FE model predicted the compared parameters well with most parameters predicted within 10% discrepancy with measured values. The location and load of the first crack in the liner (appearance of first plastic strain in the FE model) were predicted by the FE model with significant accuracy. Although the model did not show the drop in the load, the model predicted the first crack load and ultimate load well. Thus, it was concluded that the model could be used to predict the behavior for other liner thicknesses and be used for future parametric studies although the model could be further improved if additional material tests for liners were performed to better define the material model.

Keywords

CMP, SAPL, Spray applied polymeric liner, 3D-FEM, Corrugated, Plastic strain

Disciplines

Civil and Environmental Engineering | Civil Engineering | Engineering

Comments

Degree granted by The University of Texas at Arlington

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