The Lugeon Test (also called Packer Test) is an in-situ field permeability test conducted in rock formations to determine the water permeability of fractured or jointed rock mass. Water is injected into a section of borehole under pressure, and the rate of water absorption is measured. Basic Concept Water is injected under constant pressure Flow into rock depends on cracks, joints, fissures Higher water intake → higher permeability It measures permeability of rock mass, not intact rock Purpose of Test For Rock: Determine permeability of rock mass Identify fractures, joints, voids Assess grouting requirements Evaluate water tightness of rock Engineering Applications Dam foundation investigation Tunnel design Underground structures Seepage analysis Grouting design