Tyres
A. Pavement
B. Structure
C. Subgrade
Duplicate

Stress Warning

Calculation outputs horizontal tensile stresses in the unbound structural layers, which are unrealistic for unbound materials. You should consider e.g. the use of steelnets, geogrids or other types of reinforcement to limit the tensile stresses.

Odemark bearing capacity (MPa)

B. Structure

Strain microstrain

Stress distribution (max) (KPa)

C. Subgrade

Strain microstrain

Stress distribution (max) (KPa)

Instructions

The wheel load is 50 kN representing a 10 ton axle load.
The road structure contains three layers: A. pavement, B. structure and C. subgrade.

Tyres

Select the loading configuration. There are two options for tyre types: Single and Dual.
Select the tyre pressure: 800 kPa (normal), 400 kPa (CTI) or 200 kPa (CTI with very low pressure, only a few examples have been calculated for this demo).

A. Pavement

Select the modulus for the bound layers: 800 MPa (poor), 1500 MPa (moderate) or 2800 MPa (good).
Select the thickness of the bound layers: 1 cm (= gravel road), 5 cm, 10 cm or 20 cm.

B. Structure

Select the modulus for the unbound structure: 40 MPa (poor), 100 MPa (moderate) or 250 MPa (good).
Select the thickness of the unbound structure: 10 cm, 20 cm, 40 cm or 80 cm.

C. Subgrade

Select the modulus for the subgrade: 5 MPa (weak), 20 MPa (moderate) or 80 MPa (strong).

Results

The results diagram summarises the stresses and strains in the road structure at the most critical positions for the development of permanent deformation. The strain in the pavement layers is shown as a two-headed arrow located at the bottom of the bound layers. The length of the arrow indicates the amount of strain. A long arrow indicates a high strain. Strains in the structure and subgrade are shown as a compressible rectangle in each layer. The compressed height of the rectangle indicates the amount of strain. A very compressed rectangle indicates a high strain. Arrows and rectangles are coloured to represent the risk of permanent deformation or failure in the layer. Green means a safe stress and strain level. Yellow means a moderate stress and strain level. Red means a high stress and strain level and high risk for failure. Black means that the layer will fail. The weakest layer in the arrangement defines the overall rating of the whole road structure.

A. The horizontal tensile strain at the bottom of the bound layers.
B. The vertical compressive stress and strain at the upper part of the unbound layers.
C. The vertical compressive stress and strain on the top of the subgrade.

In addition to summarising the stresses and strains in the road layers, the diagram also shows the bearing capacity calculated at the top of the subgrade and each structural layer using the Odemark method.

Pressing the "duplicate" button at the top right corner of the results diagram will move your current model to the right side of the screen and allow you to calculate and compare another structural option.