Theoretical Evaluation of the Transient Response of Constant Head and Constant Flow-Rate Permeability Tests
Zhang M, Takahashi M, Morin RH, Esaki T
(Received 14 March 1997; accepted 2 October 1997)

Abstract
A theoretical analysis is presented that compares the response characteristics of the constant head and the constant flow-rate (flow pump) laboratory techniques for quantifying the hydraulic properties of geologic materials having permeabilities less than 10^-10 m/s. Rigorous analytical solutions that describe the transient distributions of hydraulic gradient within a specimen are developed, and equations are derived for each method. Expressions simulating the inflow and outflow rates across the specimen boundaries during a constant-head permeability test are also presented. These solutions illustrate the advantages and disadvantages of each method, including insights into measurement accuracy and the validity of using Darcy's law under certain conditions. The resulting observations offer practical considerations in the selection of an appropriate laboratory test method for the reliable measurement of permeability in low-permeability geologic materials.

Keywords:
constant head, flow pump, hydraulic gradient, low permeability, permeability test, theoretical analyses

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Author Zhang M, Takahashi M, Morin RH, Esaki T Title Theoretical Evaluation of the Transient Response of Constant Head and Constant Flow-Rate Permeability Tests Symposium , Committee on