plastic deformation ballast pockets

08:11 Dec 8, 2010 

No, I am afraid it is not exactly the same text.

08:00 Dec 8, 2010 

'Progressive Shear Failure
(…)
The soil moves outward and upward and cross-level develops in
the track. This failure mode is usually apparent from soil heave along the track shoulders. The rotational movement of the subgrade and addition of ballast during resurfacing create a depression known as a ballast pocket below the track. Water becomes trapped in the ballast pocket causing a further strength reduction in the subgrade soil, and the situation worsens.

Excessive Plastic Deformation

Ballast pockets also develop from permanent cumulative strain of soft, fine-grained subgrade soil as it consolidates or compacts when subjected to repeated loading (Chrismer, 1998). Vertical displacements occur as the soil compresses and addition of ballast is required to maintain track grade. Water becomes trapped in the ballast pocket
reducing the shear strength of the surrounding soil.'

I am sad to have lost my only 'agreement click' that is why I insist!

18:46 Dec 7, 2010 

There's no reason one can't have excessive ballast pockets that have developed as a result of plastic deformation.

16:38 Dec 7, 2010 

si c'est le titre, ceci explique cela

15:32 Dec 7, 2010 

auraient dû être effacés