Question

The rate of change of pore water pressure along the depth of layer represents ____________

(a) seepage pressure

(b) seepage stress

(c) hydraulic gradient

(d) permeability of the soil

The question was asked in an international level competition.

My doubt stems from Terzaghi’s Theory of One Dimensional Consolidation topic in section One Dimensional Consolidation of Geotechnical Engineering I

Answer 1

Right choice is (c) hydraulic gradient

The explanation: The hydraulic gradient is the driving force that causes groundwater to move in the direction of maximum decreasing total head. The hydraulic gradient is the change in total head divided the distance over which the change occurs. Therefore, the rate of change of pore water pressure along the depth of layer represents the hydraulic gradient.