Calculating load applied by LHD tires

[athrift]

I am designing a cemented paste fill cap to be placed over uncemented paste fill with the primary purpose of improving trafficability for 6.5 yard scooptrams (LHDs) that will be running on it. I am trying to figure out the force applied by the LHD wheels (dead load only) for a bearing capacity calculation. I know the weight and pressure applied by the loaded LHD, and the tire diameter and width. To get the force applied, I need to figure out the contact area between the tire and the paste fill cap. Is there a way of calculating or estimating this? It would be dependent on the deflection of the tire. Or is there a better way of estimating the strength requirement of the cemented paste fill cap?

 

[tarsandman]

Hey athrift

Unfortunately, you may have to physically measure the length of the tire deflection to get a reasonable number. I found that the tire manufacturers didn’t have this data, or a mode for calculating it, other than a physical measurement.

We cross some pretty sensitive utilities with our Cat 797 (400-ton) haul trucks and found the most reliable data was our own physical measurements of contact areas.

tarsandman

 

[ClydeP]

How about looking to the highway engineering handbook(s)? A thought.

I know I have had trouble with 2 yd LHDs sinking in or tearing up backfill under about 300psi compressive strength. At 500psi, no problem. Now, this was not a cap but a full 8ft deep pastefill.

 

[SeanBurston]

I would advise that you consult with your local earthmover tyre supplier.

Most suppliers produce an engineering / technical data book and in additional to tyre dimensions and peformance data the gross contact area of the tyre is normally available.

Some advice from the supplier may be required to determine how the gross contact area varies with:
- inflation pressure,
- whether the unit is loaded or empty, and
- the material type,
but it is a good start.

Regards,


Sean Burston
Senior Project Engineer
Peak Downs Coal Mine
Leighton Contractors Pty Ltd