Digging and "distructive behaviour ie. chewing" are natural dog behaviours, however, unwanted in our human world. Some dogs are more prone to digging (terriers especially, hunting breeds like basset, beagle, dachshund) than others, but it is a natural trait of all dogs.
I agree that digging becomes more pronounced if a dog is bored and needs to release the energy that builds up. It's up to us, people to redirect that behavior to some other stuff that IS acceptable for us humans, through play and different activities that we must find out are equally satisfying for our dogs. One of the solutions for notorious diggers is to put a sand pit in our yard and teach the dog to dig there by putting some treats, toys or whatever dog finds amusing in the sand and prizing/awarding a dog for digging only there and ignoring or moving away our dog from any ther place he attempts to dig. Same is with chewing. In the beginning restrict the area in which dog spends most of the time. It does not necessarily mean it has to be in the box. It can be a single room or a pen in the room spacious enough for a dog to move around and filled with toys he can chew on. The best toys are made of hard elastic rubber with a hole you can fill with treats, cheese, vegemite or something yummy such as Kong toys. You can also give bones (big chewy ones) or sterilised bones.
The other extremely important thing is of course, plenty of excercise, which of course does not mean just walk around the block. Plenty of walking/running/playing with us humans AND other canines are A MUST for any dog. Through play we can teach our dogs heaps of stuff including obedience. And of course, we need to be familiar with the breed we have and its needs, even if we jus try to guess it in mixed breed dogs. For example polar breeds (huskies, malamutes, samoyeds, spitz breeds) will need to have plenty of long distance walks/runs preferably in different environments, hunting breeds as well together with games of fetching, searching, scent tracking... so it's absolutely essential to chose a dog that suits your lifestyle.
Respect and you shall be respected. Animal is always right.