Formation and interpretation of dilatant echelon cracks

Formation and interpretation of dilatant echelon cracks

GEOMECHANICS Properties of Rocks and Soils ABSTRACTS 855005 Fracture frequency in mudrocks: an example from the Queenston Formation of southern Ont...

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GEOMECHANICS

Properties of Rocks and Soils

ABSTRACTS

855005 Fracture frequency in mudrocks: an example from the Queenston Formation of southern Ontario

Russel, D J; Harman, J

See also: 855085

Can Geotech J V22, NI, Feb 1985, PI-5

In surface exposures of the Queenston formation, an important fracture type appears as curved partings of generally low dip. The fractures are shown to be continuous, contorted and to be associated with small scale slickensided surfaces. Water movement along these fracture surfaces is evident. Core examination reveals many slickensided shears, whose frequency could be correlated with clay content, calcite content and point load strength index, It may be possible in this case to predict fracture frequency from a strength index test or compositional parameter.

85500 1 Geological Environment and Soil Properties. Papers prepared in conjunction with a session sponsored by the ASCE Geotechnical Engineering Division in conjunction with the ASCE Convention, Houston, Texas, 17-21 Ott 1983

Yang. RN (editor) Ncrl, York: .4SCE, 1983. 449P 855002 Geotechnical characteristics

of residual soils

Townsend, F C J Geotech Engng Div ASCE

855006 VII I I Nl, Jan 1985, P77-94

The contributions of climate, parent material, topography, drainage and age to the properties of residual soils is considered. The engineering and strength properties, compaction, plasticity. permeability and compressibility, were evaluated for lateritic, allophanic and black soils. Engineering implications in terms of slope stability and the potential of soil stabihsation treatments are discussed.

Unfrozen water content in saline soils: results using timedomain reflectometry

Patterson. DE; Smith, M W Can Geotech J V22, NI, Feb 1985, P95-IO1

On the engineering properties of salina soil

Combined TDR-dilatometry tests were used to determine whether the TDR technique could be used on frozen saline soils. Unfrozen water contents determined were in good agreement with those measured using conventional methods, with no marked influence due to salinity. A novel probe for field testing with TDR is described, which may be used to help predict the behaviour of saline permafrost for engineering purposes.

Stipho, A S Q J Engng Geol V18, N2, 1985, Pl29-I37

855007

855003

Subsoil in desert regions tends to be highly saline. The nature of salt precipitation in soil is described and the effects of salt content on the laboratory-measured properties of desert soils are investigated. Foundation problems arising due to the various concentrations of sodium or calcium chlorides in the soil are discussed.

Texture, structure, composition

and density

855004 Hemispherical

projection methods in rock mechanics

Priest, SD Loudon: George .4ilen and Unwin, 1985, 124P

Graphical methods are described by which three dimensional properties, such as the structural features which control the behaviour of jointed or fractured rock. can be plotted and analysed on a sheet of paper. It includes chapters concerning the analysis of borehole data. statistical analysis of orientation data. analysis of forces, kinematic analysis of rigid blocks by inclined hemisphere projection methods and analysis of the stability of rigid blocks.

Microstructure of loess soil in China relative to geologic environment

Gao Guorui In: Geological Environment and Soil Properties (paper prepared in conjunction with the ASCE Geotechnical Engineering Division and the ASCE Convention, Houston, Texas, 17-21 Ott 1983) P121-136. Pub1 New York: AXE, 1983

The engineering properties, especially collapsibility, of Chinese loess soils were measured and fabrics examined using scanning electron microscopy. Composition and geochemical properties were closely related to geologic environment. The spaced granular structure was the essential reason for collapsibility. Regional variation in collapsibility could be related to microstructure. Microstructural analysis also contributed to an interpretation of the formation and development of loess.

Fracture processes 855008 Formation and interpretation of dilatant echelon cracks

Pollard. D D; Segall, P; Delaney, P T Bull Geoi Sot Am V93, N2, Dee 1984, P1291-1303

Echelon cracks grow from a single dilating parent crack because of a change in orientation of the applied stresses. The stress fields necessary for their initiation, their growth and form (helicoidal arrays) and the surface energy considerations which contribute to their form are considered mathematically.

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