You're right in assuming that ground pressure is low. Consider that a tracked vehicle should be able to pass over dry sand and mud without sinking in - there is a lot of area under a tank track and the load applied to the soil 'fans out' rapidly with increasing depth. So at 1 metre below the surface, I would expect to see very little compressive load.

As for impact, this depends on speed and the suspension and track pad design. It may be somewhat higher than from a wheeled vehicle, but modern track and suspension systems are quite compliant and we are encouraged to make them 'seismologically stealthy'. Older tanks do vibrate the ground a bit more.

In conclusion, I would doubt if a tank is substantially more severe than a comparable wheeled vehicle, althouigh I expect there are sporadic cases of damage to buried pipes caused by tanks.

The ISTVS (International Society of Terrain Vehicle Systems) - if it still exists - may have some data. Hope this helps.

John