Pore pressure response to barometric pressure change in Champlain clay: Prediction of the clay elastic properties

Influence of seasonal hydraulic head changes on slug tests conducted in shallow low-permeability soils

“…Test conducted during dryer months (e.g., July in Lachenaie), tend to produce negative H 0 values. This trend compares well with the hydraulic head time series obtained by Marefat et al (2015) and with H 0 values obtained for numerical slug tests conducted with a cyclic hydraulic head boundary based on the same experimental hydraulic head time series. The relationship between K and seasonal head variations is more obscure as it is influenced by clay properties and test parameters.…”

“…The main objective of this paper is to evaluate the influence of seasonal head changes on real slug tests using the Lachenaie dataset and numerical slug test results based on the seasonal head cycles recorded in Lachenaie with vibrating wire piezometers (VWPs) (Marefat et al, 2015). The paper first introduces the methodology for the field tests, the hydraulic head monitoring and the numerical slug tests.…”

“…Since then, pore pressure and barometric pressure measurements have been recorded every 15 minutes. A detailed description of the VWPs installation and pore pressure correction from barometric pressure effects was presented by Marefat et al (2015).…”

“…For each MW, the difference between the hydraulic head on a given date and its mean value since installation is plotted. Raw hydraulic head data were corrected for the influence of barometric pressure changes using loading efficiency values (ratios between changes in pore pressure and barometric pressure) of respectively 0.92 and 0.80 for the upper and lower MWs of site 2, and 0.77 and 0.50 for the upper and lower MWs of site 6(Marefat et al, 2015).Even if the hydraulic head cycle amplitude varies from one site to another and at different depths within the clay layer, the frequency and general aspect of the hydraulic head cycles are similar for most VWP records. These typical hydraulic head cycles are exemplified onFig.…”

Avoiding confusion between pressure front pulse displacement and groundwater displacement: Illustration with the pumping test in a confined aquifer

“…PFPD is the kinematic wave, or mechanical wave, induced by a pressure differential caused, for example, by pumping (in the example of the pumping well); this wave is displaced and propagates or diffuses over time, starting from the well and moving outwards throughout the aquifer. Note that other forces may induce the propagation of a pressure wave, for example, tides and fluctuations in atmospheric pressure in aquifers and aquitards; these phenomena have been presented in different studies (Carr & Van Der Kamp, ; Evans, Beavan, Simpson, & Mousa, ; Marefat, Duhaime, & Chapuis, ; Merritt, ).…”