00382931

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http://onlinepubs.trb.org...s/trr/1983/919/919-003.pdf

https://scholar.google.co...dson&publication_year=1983

The Piedmont and Blue Ridge form a band of crystalline rocks that extend from New Jersey southwest into Alabama. They are deeply and irregularly weathered into residual soils without appreciable transportation. The residual soils retain the mineral segregation, mineral alignment, and structural defects of the parent rocks. These are reflected in nonhomogeneous and anisotropic engineering properties. The soils inherit large residual stresses from the tectonically disturbed rock that are not related to overburden weight. They are stronger than their high void ratios imply. However, they exhibit localized surfaces of weakness that are responsible for excavation cave-ins and landslides despite average strengths that indicate stability. Settlements due to imposed loads can be significant and nonuniform, particularly when the void ratios exceed 1.5. Settlements computed from ordinary consolidation theory usually exceed those observed, probably because of unknown residual stresses and pseudopreconsolidation. Initial settlements are large because the upper strata are partly saturated, hydrodynamic settlement is rapid, and secondary compression is often large because of the large mica content. The deeper horizons of residual soil (partly weathered rock) when loosened by ripping or blasting produce angular gravelly silty sands that are dense, strong, incompressible, and slow to drain when compacted. The more completely weathered residual soils produce sandy silts and silty sands. Their density and incompressibility vary inversely with their mica content. The usual soil classification systems (ASTM-Unified or AASHTO) are poor indexes to residual soil behavior. Instead, void ratio and defect characterization in undisturbed soil and mica content and compacted density in embankment materials are more reliable. (Author)

Publication of this paper sponsored by Committee on Soil and Rock Properties. Distribution, posting, or copying of this PDF is strictly prohibited without written permission of the Transportation Research Board of the National Academy of Sciences. Unless otherwise indicated, all materials in this PDF are copyrighted by the National Academy of Sciences. Copyright © National Academy of Sciences. All rights reserved

01420430

pp 10-16

1983

Transportation Research Record

0309036070

Print

Figures (11) ; Maps (1) ; Photos (5) ; References (8)

Compressibility; Crystalline rocks; Density; Drainage; Gravelly soils; Mica; Properties of materials; Reliability; Residual soils; Sand; Settlement (Structures); Silty sands; Soil types; Soils; Strength of materials; Stresses; Void ratios; Weathered rock

Soil properties

Geotechnology; Highways; Hydraulics and Hydrology; Materials; I41: General Soil Surveys

TRIS, TRB

Apr 30 1984 12:00AM

• CAUTIONS OF REINFORCED EARTH WITH RESIDUAL SOILS
• ESTIMATION OF EFFECTIVE STRENGTH PARAMETERS OF WELL-BEHAVED CLAY
• LANDSLIDE ANALYSIS CONCEPTS FOR MANAGEMENT OF FOREST LANDS ON RESIDUAL AND COLLUVIAL SOILS
• THICKNESS OF WEATHERED MANTLE IN PIEDMONT: VARIABILITY AND SURVEY TECHNIQUES
• UNDRAINED SHEAR STRENGTH OF SATURATED CLAY