The purpose of this study is to confirm the assumption that the stress-strain behavior of soil body at the interface with lining can be the cause of the cavity formation behind the lining space. The plastic deformation zones in soil from the computer modelling geometrically agree with the locations of cavities detected by the in-situ geophysical measurements using the method of impact response. This suggests that the stress-strain behavior and transition of soil body into a plastic strain state can cause cavity formation. The cavity formation alters acoustic response of the lining to impact, which is used to detect cavities.