A unit dedicated to mechanically loading a tubular sample. At least one packer is housed in a sample at a test zone, having a longitudinal extension greater than that of the test zone and including i) a first pressure mechanism to cause local variation in the diameter of at least a first portion of the packer so as to apply the packer against an internal surface of the sample at the test zone, ii) a second pressure mechanism exerting a first selected internal pressure over a portion of the internal surface located at a second portion of the packer, and/or iii) a third pressure mechanism to cooperate with at least one plug member attached to the sample at a distance from one end of the packer to define a zone of action, to exert on the sample a second selected internal pressure at the zone of action.