Flexible pavement design.ppt - IIT Bombay

Flexible Pavement Design

Assume Pavement Configuration

Compute Pavement Responses Using Structural Models

Input ?Material Properties ?Axle Load

Compute Allowable Number of Repetitions of Standard Axle Using Distress Models

?Failure Criteria ?Reliability

Find Expected Number of Repetitions of Standard Axle on Design Lane from Traffic Analysis

No

DR

Satisfactory?

Yes

Final Design

Mechanistic Method of Pavement Design

Design Procedure of IRC

Design Approach and Criteria

The following three types of pavement distress resulting from repeated application of traffic are considered:

(i) Horizontal tensile strain at the bottom of the bituminous layer

(ii) Vertical compressive strain at the top of the subgrade

(iii) Pavement deformation with in the bituminous layer

The deformation with in the bituminous layer is assumed to be controlled by meeting the mix design requirements

Failure Criteria

Fatigue Cracking

Is due to the build up of tensile strain at the bottom of Asphaltic Concrete Layer Pavement is considered failed if 20% of the surface has cracked

Rutting Failure

Is due to the build up of excessive compressive strain at the top of subgrade layer Pavement is considered failed if it exhibits a rut depth of 20 mm.

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