I understand that the burying of Sheimos, in a sense, is similar to burying a dead body. I assume that in the same way that you cannot dig up a dead body except for some unusual situations, you cannot dig out Sheimos. Is that true, or are there specific situations where you would be allowed to do this? If so, please cite 1 or 2 examples.
In the new Masores Moshe volume 2 page 270 it quotes this exact question which was posed to Rav Moshe Feinstein. He was asked if one can exhume seforim from a grave which only seforim are buried. Rav Moshe allowed one to do so and his reasoning was that only the dead have an inyun on not being disgraced and prohibition of pleasure from them.
From the Sefer Ginzei Kodesh perek 15:10:24(referenced by chiddushei Torah) writes that a big hole where one buries shemos from time to time one does not need to cover it with earth until they are finished(or its full). However, one has to protect the shemos from rain and wind (I guess a tarp would suffice). The reason is so the shemos won't come to degradation,but it seems one can extract shemos as long as the shemos dosen't get ruined because of it.
Even things which need a kli (Sta"m) it seems one can extract it as long as the buried items don't get ruined. It seems the purpose of the kli is to keep it from being degraded or decay faster.
*This is my extrapolation from reading the sefer,unfortunately I could not find anywhere in the sefer where he addresses this issue explicitly ,but from the other halachos in the sefer it seems that if it won't be degraded it should be fine to extracthe shemos in a respectable manner.Of course ask a Rav for Halacha lmaase.