Penetration Rate-Controlled Electrical Resistivity and Temperature Piezocone Penetration Tests in Warm Ice-Rich Permafrost in Northern Quebec, Canada

Abstract

Electrical resistivity and temperature piezocone penetration test (RTCPTU) was carried out in warm ice-rich permafrost formed in silty soil near Umiujaq, Northern Quebec, Canada, to study the cryostratigraphy of permafrost and adapt soil classification charts for the interpretation of RTCPTU in such environment. A linear pushing system based on an actuator technology was used to accurately control the penetration rate of the piezocone in permafrost.According to the interpretation of the RTCPTU logs, cryostratigraphic contacts and layers such as the thawing front, permafrost table and base, active layer, ice-rich permafrost and perennially noncryotic ground, layers of ice-poor frozen silt, and ice lenses were identified. Due to its reticulated cryostructure made of a sequence of centimetric thick ice lenses and frozen soil layers, ice-rich permafrost is characterized by extremely variable values of cone resistance and friction ratio corrected for pore pressure effects, pore pressure, and electrical resistivity between 5 and 50 MPa, 0.01 and 2%, near zero and 10 MPa, and 0.01 and 20 kΩ-m, respectively. Cone resistance up to 50 MPa, friction ratio down to 0.01%, pore pressure near 10 MPa, and electrical resistivity close to 10 kΩ-m are characteristics of thick ice lenses. The layers of ice-poor frozen silt with high unfrozen water content have cone resistance lower than 10 MPa, friction ratio in excess of 1%, pore pressure lower than 3 MPa, and electrical resistivity lower than 1 kΩ-m.Based on permafrost behaviour types as characterized from the RTCPTU logs, new zones are proposed in soil classification charts to identify frozen soils. These adapted soil classification charts are helpful to practitioners for the interpretation of RTCPTU carried out in permafrost.

Long‐Term, High‐Resolution Permafrost Monitoring Reveals Coupled Energy Balance and Hydrogeologic Controls on Talik Dynamics Near Umiujaq (Nunavik, Québec, Canada)

“…The ice content of the permafrost mounds varies between 40% and 90% (R. Fortier et al., 1994, 2008), while the unfrozen water content values average around 10% where ground temperature is lowest at −2°C (LeBlanc et al., 2004). The permafrost temperature is close to 0°C and generally varies between −0.1 and −2°C depending on the depth (R. Fortier et al., 2008; R. Fortier & Yu, 2012; LeBlanc et al., 2004).…”

“…Due to frost heave and the accumulation of segregated ice lenses, permafrost in the valley exists in the form of raised periglacial landforms, or permafrost mounds, sometimes called lithalsas (Allard et al., 1986; Allard & Seguin, 1987; Harris, 1993). Previous studies carried out at several permafrost mounds located in the Tasiapik Valley focused on permafrost cryostratigraphy by conducting electrical resistivity and temperature piezocone penetration tests (R. Fortier & Yu, 2012). Results revealed that the stratified cryostructure consists of a complex reticulated sequence of centimetric ice lenses and frozen soil layers (fine sediments or sand beds) (Calmels & Allard, 2008; R. Fortier et al., 2008; R. Fortier & Yu, 2012).…”

“…Previous studies carried out at several permafrost mounds located in the Tasiapik Valley focused on permafrost cryostratigraphy by conducting electrical resistivity and temperature piezocone penetration tests (R. Fortier & Yu, 2012). Results revealed that the stratified cryostructure consists of a complex reticulated sequence of centimetric ice lenses and frozen soil layers (fine sediments or sand beds) R. Fortier & Yu, 2012).…”

Development of a three-dimensional geological model, based on Quaternary chronology, geological mapping, and geophysical investigation, of a watershed in the discontinuous permafrost zone near Umiujaq (Nunavik, Canada)

“…Typical permafrost thickness in the Tasiapik Valley varies from about 4 m for small permafrost mounds to in excess of 25 m for permafrost plateau ( Fig. 6b; El Baroudi and Fortier 2014;Fortier and Yu 2012). The active layer, the surficial layer affected by freeze-thaw cycles, is from 1.5 to 2 m thick where the silty sand unit outcrops in the lower valley.…”

“…5 and 6b), and the results from the geophysical investigation (Figs. 6, 7, and 8), along with other sources of information including cone penetration tests and other geophysical investigations (Buteau et al 2005; El Baroudi and Fortier 2014;Fortier and Yu 2012;LeBlanc et al 2004;LeBlanc et al 2006), were used to build a 3D geological model of the studied watershed in the Tasiapik Valley (Fig. 9).…”