Geophysical and Geotechnical Characterization of a Sensitive Clay Deposit in Brownsburg, Quebec

Abstract

The results of a geophysical and geotechnical investigation in a sensitive clay deposit affected by numerous landslide scars in Vases Creek Valley near Brownsburg, Quebec, Canada are presented herein. The main objective of this investigation was to assess the suitability of electrical resistivity measurements in marine clay deposits for mapping out areas prone to flowslides. In addition to a 1.6 km-long electrical resistivity tomography (ERT) carried out perpendicular to the axis of the Vases Creek Valley, six piezocone penetration tests and five boreholes with sampling were also performed along the geophysical survey line. Moreover, standard geotechnical parameters and pore water salinity, as well as electrical resistivity of undisturbed clay samples were measured in the laboratory. According to the correlations found between the remoulded shear strength, the pore water salinity and the electrical resistivity, clay samples with salinity below 6.2 g/l are characterized by remoulded shear strength below 1 kPa and electrical resistivity above 2.8 and 10 Ωm measured respectively in the field and in the laboratory. In such conditions, sensitive clay deposits can be prone to flowslides if all other criteria are also met. Based on this resistivity limit value, only one small area of non-sensitive clay was identified in the interpretative stratigraphic cross-section assessed from the field investigation. Otherwise, the deposit is entirely composed of sensitive clay. The ERT is a promising geophysical tool for the delineation of areas prone to large landslides in eastern Canada.

Using archaeological and geomorphological evidence for the establishment of a relative chronology and evolution pattern for Holocene landslides

“…ERT is known as a method with which landslide slip surfaces can be identified, so consequently, the geometry of the landslides can be understood [108–114]. The resistivity can indicate the presence of clay minerals, a high degree of fracturing and saturation with water, which usually gives low resistivity (under 100 ohm-m), compared to hard rock, unfractured, or unsaturated water conditions, which usually have high resistivity [115,116]. When claystones are weathered and contain water, they can have smaller resistivity values [117,118].…”

Predicting soil parameters in Maroua 1st, Cameroon, using correlations of geophysical and geotechnical data

“…The disadvantage of this method is that the measured properties cannot be integrated into the calculation formulas during the design of a structure; thus, reducing its context of use. However, by combining conventional geotechnical methods with geophysical methods, it is possible to determine the necessary results for the design of structures adapted to swelling [ 8 ].…”