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Title: STABILITY ANALYSES AND DESIGN OF CONTROL METHODS
Accession Number: 00235703
Record Type: Component
Abstract: STABILITY ANALYSES MADE ACCORDING TO THE CLASSIC THEORIES OF SOIL MECHANICS PRESENT THE BEST HOPE FOR A QUANTITATIVE MEANS OF EVALUATING EXPERINCE, AND PROVIDE A RATIONAL BASIS FOR EXTENDING EXPERIENCE FOR THE PURPOSE OF PREDICTION. PRINCIPLE EMPHASIS IS PLACED ON A SINGLE METHOD OF ATTACK, THE SWEDISH SLICE METHOD AND ON ITS APPLICATION TO THE ECONOMICS OF VARIOUS TREATMENTS. EXAMPLES ARE GIVEN FOR SITUATIONS WHERE SLIDES HAVE OCCURRED. SEVERAL METHODS ARE AVAILBALE FOR QUANTITATIVE STUDY OF THE STABILITY OF SLOPES HOWEVER, MOST METHODS REPLACE THE REAL SURFACE OF SLIDING WITH ONE HAVING A SECTION OF EITHER AN ARC OF A CIRCLE OR OF A LOGORITHMIC SPIRAL. THE USE OF THE CIRCULAR ARC ASSUMPTION IS BASED ON STUDIES OF ACTUAL FAILURE SURFACES BY THE SWEDISH GEOTECHNICAL COMMISSION AND IS FUNDAMENTAL TO THE METHOD OF ANALYSIS DEVELOPED BY FELLENIUS, CALLED THE SWEDISH METHOD OF SLICES. IN ADDITION TO AN ASSUMPTION AS TO THE FORM OF THE FAILURE SURFACE, CONVENTIONAL STABILITY ANALYSES REQUIRE OTHER FACTS AND ASSUMPTIONS, SUCH AS (1) A SHEAR FAILURE MUST HAVE OCCURRED OR MUST BE A THREAT, (2) THE AVERAGE SHEARING RESISTANCE ALONG THE SLIP- SURFACE AT THE TIME OF FAILURE MUST BE KNOWN, AS MUST ANY VARIATION FROM THE AVERAGE, (3) AN ASSUMPTION MUST BE MADE THAT THE CONDITIONS THAT EXIST ALONG A NARROW SLICE OR CROSS SECTION OF THE SLIDE CAN BE USED TO DESIGN AGAINST MOVEMENT IN THE REMAINDER OF THE AREA, (4) AN ASSUMPTION MUST BE MADE AS TO THE LOCATION OF THE PIEZOMETRIC OR THE GROUND WATER SURFACE AT THE INSTANT OF FAILURE, AND (5) THE VALUE OF THE SAFETY FACTOR MUST BE ESTABLISHED. IN THIS DISCUSSION THE MOST FREQUENTLY USED EXPRESSION OF THE SAFETY FACTOR IS THE RATIO BETWEEN TOTAL SHEARING RESISTANCE AND TOTAL SHEARING FORCE. THE SWEDISH METHOD OF SLICES APPLIES TO MOST COHESIVE SOILS ABOVE THE WATER TABLE WHICH HAVE A SHEARING RESISTANCE APPROXIMATELY EQUAL TO COHESION PLUS DISTRESS NORMAL TO THE SLIP-SURFACE TIMES THE TANGENT OF THE ANGLE OF INTERNAL FRICTION. IN THE ANALYSIS, THE ASSUMPTION IS MADE THAT THE SURFACE OF FAILURE OF A SLOPE CAN BE DEFINED AS HAVING A SECTION REPRESENTED BY THE ARC OF A CIRCLE, AND THAT THE SOIL WITHIN THE CIRCLE ROTATES ABOUT A CERTAIN POINT, THE CENTER OF THE CIRCLE. THE PROCEDURE REQUIRES A CROSS-SECTION, PLOTTED TO SCALE, OF THE SLOPE BEING ANAL- YZED. THE CIRCULAR ARC THAT REPRESENTS THE FAILURE SURFACE IS THEN DRAWN ON THE CROSS-SECTIONS, FORMING A CIRCULAR SEGMENT REPRESENTING THE SLIDING MASS. IT IS SHOWN HOW THE METHOD OF SLICES CAN ALSO BE USED IN ESTIMATING THE SHEARING RESISTANCE AT THE TIME OF FAILURE. EXAMPLES ARE GIVEN OF THE APPLICATION OF THE METHOD TO SPECIFIC CONTROL MEASURES FOR: (1) EXCAVATION, INCLUDING REMOVAL OF MATERIAL AT HEAD OF SLIDE, FALTTENING THE SLOPE, AND BENCHING OF SLOPES, (2) DRAINAGE, (3) RESTRAINING STRUCTURES INCLUDING ROCK BUTTRESS AND EARTH BUTTRESS, CRIBS AND RETAINING WALLS, AND (4) PILING.
Supplemental Notes: pp 189-216, 10 FIG, 16 TAB, 16 REF. 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.
Monograph Title: Monograph Accession #: 00234453
Authors: Baker, R FYoder, E JPublication Date: 1958
Media Type: Digital/other
TRT Terms: Uncontrolled Terms: Old TRIS Terms: Subject Areas: Geotechnology; Highways; Safety and Human Factors
Files: TRIS, TRB
Created Date: Aug 17 1970 12:00AM
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