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Theoretical analysis of the transient pressure response from a constant flow rate hydraulic conductivity test
Author(s) -
Morin Roger H.,
Olsen Harold W.
Publication year - 1987
Publication title -
water resources research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.863
H-Index - 217
eISSN - 1944-7973
pISSN - 0043-1397
DOI - 10.1029/wr023i008p01461
Subject(s) - hydraulic conductivity , consolidation (business) , mechanics , geotechnical engineering , hydraulic head , aquifer , specific storage , transient (computer programming) , materials science , groundwater flow equation , pressure head , flow (mathematics) , pore water pressure , volumetric flow rate , geology , thermodynamics , soil science , groundwater , groundwater flow , soil water , physics , computer science , operating system , accounting , groundwater recharge , business
Incorporating a flow pump into a conventional triaxial laboratory system allows fluid to be supplied to or withdrawn from the base of a sediment sample at small and constant rates. An initial transient record of hydraulic head versus time is observed which eventually stabilizes to a constant steady state gradient across the sample; values of hydraulic conductivity can subsequently be determined from Darcy's law. In this paper, analytical methods are presented for determining values of specific storage and hydraulic conductivity from the initial transient phase of such a constant flow rate test. These methods are based on a diffusion equation involving pore pressure and are analogous to those used to describe the soil consolidation process and also to interpret aquifer properties from pumping tests. Examination of the effective stress distributions within the test specimen induced during this type of measurement shows that values of specific storage corresponding to both compression and rebound conditions can be deduced and differentiated simply by reversing the direction of fluid flow. Applicability and limitations of the methods are illustrated with analyses of recently reported flow pump test measurements conducted on a silty‐clay specimen.