dirtandrock
Geotechnical
- Mar 8, 2010
- 8
Howdy,
I'm looking at the preliminary design of an MSE Wall for a job. I suppose I'm also interested (or atleast the structural eng will be for wall design) in this question for the adjacent concrete retaining wall that forms the backwall of a large rock crusher.
The wall is up to 28 m (92 ft) high (in the center for the concrete wall and some of the MSE), but the MSE wall slopes downwards at a 1v:2h slope away from the center mine truck dump point to a height of ~ 4 m (13 ft) at the edges.
Typically 250 psf is speficied for traffic surcharge for a retaining wall including mse walls, but in my case we will have a large mine truck which will be dumping up adjacent to either wall. This is much heavier than a typical work truck or even concrete truck, etc.
Its specs are generally:
[Komatsu 830e-ac: max front axle 127,000 kg, back 258,000 kg, tire pressure 827 kPa (120 psi)]
Anyways, my question is this:
1. Can you provide me a reference to calculate the truck bearing pressure and hence lateral earth pressure on the walls. 250 psf seems widly inadequate for this case.
2. A reference on the effect of this pressure, as typically we would assume a surchage pressure acting at 0.5 x Height, but this wall is 100 ft tall therefore where does the effect of the surcharge become neglible? Assuming it acts on the base of the wall seems like way overconservatism.
3. Any other general thoughts.. the bearing capacity of the foundation soil is 400 kPa, some of the wall will be founded on bedrock.
I'm looking at the preliminary design of an MSE Wall for a job. I suppose I'm also interested (or atleast the structural eng will be for wall design) in this question for the adjacent concrete retaining wall that forms the backwall of a large rock crusher.
The wall is up to 28 m (92 ft) high (in the center for the concrete wall and some of the MSE), but the MSE wall slopes downwards at a 1v:2h slope away from the center mine truck dump point to a height of ~ 4 m (13 ft) at the edges.
Typically 250 psf is speficied for traffic surcharge for a retaining wall including mse walls, but in my case we will have a large mine truck which will be dumping up adjacent to either wall. This is much heavier than a typical work truck or even concrete truck, etc.
Its specs are generally:
[Komatsu 830e-ac: max front axle 127,000 kg, back 258,000 kg, tire pressure 827 kPa (120 psi)]
Anyways, my question is this:
1. Can you provide me a reference to calculate the truck bearing pressure and hence lateral earth pressure on the walls. 250 psf seems widly inadequate for this case.
2. A reference on the effect of this pressure, as typically we would assume a surchage pressure acting at 0.5 x Height, but this wall is 100 ft tall therefore where does the effect of the surcharge become neglible? Assuming it acts on the base of the wall seems like way overconservatism.
3. Any other general thoughts.. the bearing capacity of the foundation soil is 400 kPa, some of the wall will be founded on bedrock.
