The coco fiber is easily passed through them with out harm. How damp is the soil? Rule of thumb is moist or heavily damp not mud. They will stop burrowing if the soil is to water logged.
Do you de-chlorinate your frogs water and do you use de-chlorinated water to expand his soil? How old and how big is your frog?
Also answer the question that are in this thread http://www.frogforum.net/pacman-frog...enclosure.html Post your answers back here in your thread. We need more information.