Journal article Open Access

Analysis of Stress- Strain and Deflection of Flexible Pavements Using Finite Element Method Case Study on Bako-Nekemte Road

Wayessa, Shiferaw Garoma; Quezon, Emer Tucay Quezon; Kumela, Tarekegn

In Ethiopia, the failure of roads occurred before the handover period. Most roads in Ethiopia, composed of flexible pavements of about 99%. Nowadays, the failure of the surface of flexible pavement roads is common before the expected design period. One example is Bako-Nekemte road, which became a critical issue in the study area. The most common parameters that cause stress, strain, and deflection of the roads are loads and pressures that come from vehicles. In this research study, the modulus of elasticity, Poisson’s ratio and thickness of each layer were characterized. The load magnitude, contact pressure (or load radius) and location are defined for each load (wheel) considered. The finite element method (FEM) is a numerical analysis technique used to obtain the stress-strain and deflection of each pavement layer. The analytical method usually used layers thickness, loads, elastic modulus and Poisson’s ratio of the pavement materials as design parameters. The objective of this research was to study the sensitivity of the road parameters in analyzing the major causes of failure in asphalt pavement layers. Fatigue cracking and rutting deformation which emanated from the critical tensile strains at the bottom of the asphalt layer and the critical compressive strains on the top of the subgrade, the finite element method used to relate the standard specification of ERA and laboratory test results conducted. This research studied the analysis of stress-strain and deflection of flexible pavements using the Everstress finite element method. The Everstress FEM program will take into account any stress-dependent stiffness characteristics of each layer. This research dealt with a way to reduce deflections by varying the design configuration, such as increasing the HMA modulus, the base modulus, sub-base modulus, the subgrade modulus and increasing thickness of each layer. Results indicated that based on types of materials, such as the value of elastic modulus and poison’s ratio, in layer-1 varied from 1500 to 3500 MPa, in layer-2 from 200 to 1000MPa, in layer-3 from 100 to 250 MPa, and in layer-4 from 20MPa to 150MPa.

Pavement Performance
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