Abstract：Field and experimental results of localized deformation bands in high porosity rocks such as compaction bands，shear bands and dilation bands are introduced. The shear bands discussed here are small faults of outcrops in high porosity sandstones with displacements of a few millimeters to a few centimeters. The porosity of compaction bands is lower than that of the wall rocks. The compaction bands have strong weathering resistance and can block the fluid transmission. They bands are correlated to water and petroleum industry，and have practical significance to the storage of nuclear wastes and design of nuclear depots. Further more，they are perpendicular to the maximum principal stress，and correspond to the first shelf of the s-e curves of the symmetric triaxial compression tests under low ambient pressure. From the observation of acoustic emission(AE)，the AE concentration at the lower end of the sample moves toward the center of the specimen with the increase of the differential stress，which corresponds to the formation of the compaction bands. This phenomenon is in agreement with the observation of sample sections under different confining pressures. If keeping on loading，the brittle rocks finally fail. So the compaction bands are localized deformations that appear in the brittle-ductile transition. On the contrary，the porosity of dilation bands is quite bigger than the surrounding rocks. Thus dilation bands are perpendicular to the minor principal stress，accompanied by shear bands. The research of localized deformations has been greatly concerned by geosciences researchers recently，and becomes one of the hot issues in the study of rock mechanics and crust deformation.
