Geotechnical characteristics of sensitive Leda clay at Canada test site in Gloucester, Ontario

A modified piezocone penetration test (CPTu) analytical solution based on spherical cavity expansion and critical state soil mechanics (SCE–CSSM) is employed for assessing yield stress, undrained shear strength, and flow parameters in sensitive Leda clay at the Gloucester test site. For sensitive and structured clays, the formulation relies on the mobilized effective stress friction angle ([Formula: see text]) defined at two parts of the stress–strain curve: (i) peak stress ([Formula: see text]) and (ii) maximum obliquity ([Formula: see text]). Input parameters for assessing the overconsolidation ratio ([Formula: see text], where [Formula: see text] is preconsolidation stress and [Formula: see text] is current effective vertical stress) from CPTu results include: undrained rigidity index (IR = G/su, where G is shear modulus and su is undrained shear strength), plastic volumetric strain potential (Λ = 1 – (Cs/Cc), where Cs is swelling index and Cc is virgin compression index), and effective friction angles ([Formula: see text] and [Formula: see text]). A direct CPTu means of assessing the undrained rigidity index in a reliable manner is also developed that gives the Nkt cone factor and matches profiles of undrained shear strength from triaxial compression tests (suTC). The modified solution is also implemented on two additional sites: a sensitive-quick clay in Norway and structured varved clay from New England. Interpretations of the coefficient of consolidation and permeability from pore-water pressure dissipation tests at Gloucester are evaluated using the SCE–CSSM formulation and shown to be comparable with independent laboratory and field tests.

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Characterisation of weathered clayey soils responsible for shallow landslides

Natural Hazards and Earth System Science ◽

10.5194/nhess-6-825-2006 ◽

2006 ◽

Vol 6 (5) ◽

pp. 825-838 ◽

Cited By ~ 21

Author(s):

C. Meisina

Keyword(s):

Slope Angle ◽

Test Site ◽

Linear Shrinkage ◽

Strain Engineering ◽

Shallow Landslides ◽

Point Of View ◽

Slope Instability ◽

Clayey Soils ◽

Landslide Occurrence ◽

Geotechnical Characteristics

Abstract. Shallow earth translational slides and earth flows, affecting colluvial soils derived by the weathering of the clayey bedrock, are a recurrent problem causing damage to buildings and roads in many areas of Apennines. The susceptibility assessment, e.g. slope stability models, requires the preliminary characterization of these superficial covers (lithology, geotechnical and hydraulic parameters). The aim of the work is to develop and test a methodology for the identification and mapping of weathered clayey soils responsible for shallow landslides. A test site in Northern Apennines (Province of Pavia) was selected. Argillaceous and marly successions characterize the area. Shallow landslides occurred periodically due to high intensity rainfalls. Trench pits were used for the soil profile description (lithology, structure, grade of weathering, thickness) and sampling. The main geological, topographic and geomorphologic parameters of shallow landslides were analysed. Field surveys were integrated with some geotechnical laboratory tests (index properties, suction and volumetric characteristic determination, methylene blue adsorption test, linear shrinkage, swell strain). Engineering geological zoning was carried out by grouping the superficial soils on the basis of the following attributes: topographic conditions (slope angle), landslide occurrence, lithology (grain size), geometry (thickness), lithology of the bedrock, hydrogeological and geotechnical characteristics. The resulting engineering-geological units (areas that may be regarded as homogeneous from the geomorphologic and engineering – geological point of view) were analysed in terms of shallow slope instability.

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Magnitude Estimation and Cross-Modal Matching of Lingual Vibrotactile and Auditory Sensation

Journal of Speech Language and Hearing Research ◽

10.1044/jshr.3203.698 ◽

1989 ◽

Vol 32 (3) ◽

pp. 698-702 ◽

Cited By ~ 2

Author(s):

Daniel Harris ◽

Donald Fucci ◽

Linda Petrosino

Keyword(s):

Auditory Stimulus ◽

Magnitude Estimation ◽

Sensory Processing ◽

Test Site ◽

Systematic Investigation ◽

Thenar Eminence ◽

Stimulus Range ◽

Psychophysical Scaling ◽

Scaling Methods ◽

Response Biases

The present experiment was a preliminary attempt to use the psychophysical scaling methods of magnitude estimation and cross-modal matching to investigate suprathreshold judgments of lingual vibrotactile and auditory sensation magnitudes for 20 normal young adult subjects. A 250-Hz lingual vibrotactile stimulus and a 1000-Hz binaural auditory stimulus were employed. To obtain judgments for nonoral vibrotactile sensory magnitudes, the thenar eminence of the hand was also employed as a test site for 5 additional subjects. Eight stimulus intensities were presented during all experimental tasks. The results showed that the slopes of the log-log vibrotactile magnitude estimation functions decreased at higher stimulus intensity levels for both test sites. Auditory magnitude estimation functions were relatively constant throughout the stimulus range. Cross-modal matching functions for the two stimuli generally agreed with functions predicted from the magnitude estimation data, except when subjects adjusted vibration on the tongue to match auditory stimulus intensities. The results suggested that the methods of magnitude estimation and cross-modal matching may be useful for studying sensory processing in the speech production system. However, systematic investigation of response biases associated with vibrotactile-auditory psychophysical scaling tasks appears to be a prerequisite.

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