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TitleEmpirical geophysical/geotechnical relationships in the Champlain Sea sediments of Eastern Ontario
AuthorCrow, H L; Hunter, J A; Pugin, A J -M; Pullan, S E; Alpay, S; Hinton, M
SourceLandslides in Sensitive Clays: From Geosciences to Risk Management ; by L'Heureux, J -S (ed.); Locat, A (ed.); Leroueil, S (ed.); Demers, D (ed.); Locat, J (ed.); Advances in Natural and Technological Hazards Research vol. 36, 2013 p. 253-264, 20
Alt SeriesEarth Sciences Sector, Contribution Series 20120459
Meeting1st International Workshop on Landslides in Sensitive Clays; Laval; CA; October 28-30, 2013
Mediapaper; on-line; digital
File formatpdf
NTS31G/05; 31G/06; 31G/07; 31G/10; 31G/11; 31G/12
AreaEastern Ontario; Champlain Sea; Ottawa
Lat/Long WENS -76.0000 -74.5000 45.7500 45.2500
Subjectsgeophysics; engineering geology; surficial geology/geomorphology; clays; clay analyses; sensitive clays; terrain sensitivity; conductivity; slope failures; slope stability; slope stability analyses; slope deposits; geophysical surveys; seismic interpretations; seismic models; seismic surveys; Champlain Sea Sediments; geotechnical surveys
Illustrationslocation maps; profiles; plots
ProgramEastern Canada Geohazards Assessment Project, Public Safety Geoscience
AbstractGeophysical and geotechnical data are presented from different sites in eastern Ontario where variable geotechnical properties of Champlain Sea sediments ('Leda Clays') are found. Sites range from thick "undisturbed" silts and clays, to "disturbed" geologically similar soils (earthquake triggered landslides and other deformed materials). High-resolution seismic profiles provide stratigraphic
context for some of the boreholes drilled in the study area. Downhole geophysical logs from fourteen boreholes are compared to core sample measurements of porosity, sensitivity, and porewater conductivity to develop useful empirical relationships. According to these relationships, silt and clay sediments can be sensitive or quick when formation conductivity drops below 100 mS/m. Conversely, silts and clays with elevated conductivities (>250 mS/m) are rarely sensitive. Salinity values calculated from porewater conductivity indicate sensitive or quick behaviour may be expected in leached soils when salinity drops below 2 g/l.
Summary(Plain Language Summary, not published)
Empirical equations relating geophysical measurements to potentially problematic geotechnical behaviour in soft soils of the Champlain Sea ('Leda Clays') are presented from 14 borehole sites in eastern Ontario. Equations were developed by relating downhole conductivity and velocity data to core sample measurements of porosity, sensitivity, and porewater conductivity. These equations may help predict soil sensitivity, an important parameter in landslide hazard assessment.