How the mechanistic method can be applied for flexible pavement design?

How the mechanistic method can be applied for flexible pavement design?

Empirical-Mechanistic method of design is based on the mechanics of materials that relates input, such as wheel load, to an output or pavement response. The relationship between physical phenomena and pavement failure is described by empirically derived equations that compute the number of loading cycles to failure.

Which mechanistic model is commonly used to design pavement?

The pavement model most commonly used is called a layered elastic model, meaning that the layers are comprised of different materials, such as clay for the subgrade, crushed rock for the base, and one or more layers of HMA for the surface.

Flexible pavements are constructed of several thicknesses of asphalt or bituminous concrete layers overlying a base of granular material on a prepared subgrade. They spread the concentrated aircraft wheel loads throughout their depth until the load at the base of the pavement is less than…

What are the design steps of flexible pavement?

A flexible pavement structure is typically composed of several layers of materials. Each layer receives loads from the above layer, spreads them out, and passes on these loads to the next layer below. Thus the stresses will be reduced, which are maximum at the top layer and minimum on the top of subgrade.

Which type of pavement has multiple layers?

A composite pavement comprises multiple, structurally different layers of heterogeneous nature. A typical example is a concrete pavement of two layers, sandwiching a brick layer. A base of roller compacted concrete and surface course of bitumen is another example.

What is the most commonly used overlay?

Explanation: The most commonly used overlay is flexible over flexible, rigid over flexible and rigid over rigid are also used but flexible is the most preferred and used pavement. Explanation: The commercial vehicles per day are considered as 150 to 1500 for pavement design studies.

Where is flexible pavement used?

Flexible pavements are constructed using bituminous materials. These can be either in the form of surface treatments (such as bituminous surface treatments generally found on low volume roads) or, asphalt concrete surface courses (generally used on high volume roads such as national highways).

How many layers of flexible pavement are there?

There are actually typically five or six layers in a flexible pavement, divided into two overlapping sections: the pavement section and the foundation section.

What is effective CBR value?

▪ Composite strength of the subgrade and the embankment soil below it is termed as EFFECTIVE CBR. ▪ This composite strength should be taken for design consideration ▪ This composite strength should be taken for design consideration rather than strength of top 500mm.

What are the layers of flexible pavement?

Typical layers of a conventional flexible pavement includes seal coat, surface course, tack coat, binder course, prime coat, base course, sub-base course, compacted sub-grade, and natural sub- grade. Seal Coat: Seal coat is a thin surface treatment used to water-proof the surface and to provide skid resistance.

How many layers are there in flexible pavement?

What are the three types of pavement?

Pavement Types

• Flexible pavements. Those which are surfaced with bituminous (or asphalt) materials. These types of pavements are called “flexible” since the total pavement structure “bends” or “deflects” due to traffic loads.
• Rigid pavements. Those which are surfaced with portland cement concrete (PCC).

What are the assumptions in flexible pavement stress analysis?

Assumptions (p. 60): • Each Layer – Continuous – – – Linearly – Material is – Finite thickness (except last layer) Topic 3 – Flexible Pavement Stress Analysis 2. Multilayer Elastic Theory (cont.) Assumptions (cont.): • Surface stresses – Circular – Vertical – Uniformly distributed • Full • Each layer continuously supported Point A Point B E1, ν1

How is two layer theory used in pavement stress analysis?

5. Two-layer Theory (Burmister) Topic 3 – Flexible Pavement Stress Analysis 5.1 Two-Layer Deflections • In one-layer theory we assumed that all layers could be represented as one – δsurface= δtop of the subgrade

How are free boundaries used in flexible pavement models?

This program also uses free boundaries on the four sides of the flexible pavement model. Additionally, the choice of element geometry (size and shape) as well as interpolation functions will influence overall model performance. The typical finite elements method approach involves the following seven steps (Huebner et al., 2001 [1] ):

What should be considered in a pavement response model?

Environmental conditions are not considered in the pavement model and the pavement materials are assumed to be linear elastic. f Pavement Response models  Flexible and rigid pavements respond to loads in very different ways.