00713473

Component

http://onlinepubs.trb.org...trr/1995/1479/1479-004.pdf

https://scholar.google.co...tark&publication_year=1995

The drained residual shear strength of overconsolidated clays is an important parameter in assessing the stability of slopes that contain a preexisting shear surface. The main issue influencing a laboratory testing program to measure the drained residual strength is whether a natural or laboratory-formed shear surface will be used. A multistage test procedure using a modified Bromhead ring shear apparatus and an overconsolidated, precut, remolded specimen is described that provides a reliable and practical method for measuring the drained residual shear strength. Results of ring shear tests on 32 clays and clay shales reveal that the drained residual strength is controlled by clay mineralogy and the quantity of clay-size particles. The liquid limit is used as an indicator of clay mineralogy, and the clay-size fraction indicates the quantity of clay-size particles, which are particles smaller than 0.002 mm. Therefore, increasing the liquid limit and clay-size fraction decreases the drained residual strength. The ring shear tests also reveal that the drained residual failure envelope is significantly nonlinear for overconsolidated clays with a clay-size fraction greater than 50% and a liquid limit between 60 and 220. Analysis of several case histories shows that this nonlinearity should be incorporated into a slope stability analysis. Previous correlations do not provide an accurate estimate of the drained residual strength because they (a) are based on only one soil index property, for example, clay-size fraction or plasticity; and (b) do not provide an estimate of the stress-dependent nature of the residual failure envelope. A new correlation is presented that is a function of the liquid limit, clay-size fraction, and effective normal stress and can be used to estimate the entire nonlinear residual failure envelope.

This paper appears in Transportation Research Record No. 1479, Engineering Properties and Practice in Overconsolidated Clays. 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

01399782

English

p. 26-34

1995

Transportation Research Record

Figures (7) ; References (34) ; Tables (2)

Case studies; Clay; Grain size (Geology); Laboratory tests; Liquid limits; Mineralogy; Nonlinear systems; Overconsolidation; Residual shear strength; Ring stress; Slope stability; Test procedures; Testing equipment

Nonlinearity; Ring shear

Geotechnology; Highways; I41: General Soil Surveys; I42: Soil Mechanics

TRIS, TRB

Nov 2 1995 12:00AM

• CHARACTERIZATION OF PRECONSOLIDATED SOILS IN RICHMOND, VIRGINIA
• DESIGN PRACTICES IN OVERCONSOLIDATED CLAYS OF NEW YORK
• ENGINEERING PROPERTIES OF OVERCONSOLIDATED PLEISTOCENE SOILS OF TEXAS GULF COAST
• GEOTECHNICAL BEHAVIOR OF OVERCONSOLIDATED SURFICIAL CLAY CRUSTS
• GEOTECHNICAL ENGINEERING PRACTICE IN OVERCONSOLIDATED CLAYS, SAN DIEGO, CALIFORNIA
• IN SITU TESTING IN OVERCONSOLIDATED CLAYS
• ISSUES AND TECHNIQUES FOR SAMPLING OVERCONSOLIDATED CLAYS
• LABORATORY METHODS FOR DETERMINING ENGINEERING PROPERTIES OF OVERCONSOLIDATED CLAYS
• OVERCONSOLIDATED GLACIAL TILLS IN EASTERN WISCONSIN
• OVERVIEW OF STATE-OF-THE-PRACTICE MODELING OF OVERCONSOLIDATED SOILS
• PROFILING YIELD STRESSES IN CLAYS BY IN SITU TESTS
• U.S. STATE OF THE PRACTICE IN SAMPLING AND STRENGTH TESTING OF OVERCONSOLIDATED CLAYS