Download Record: 1 Title: Evaluating selected factors affecting the depth of undercutting in rocks subject to differential weathering

3/24/2016
EBSCOhost
Record: 1
Title: Evaluating selected factors affecting the depth of undercutting in
rocks subject to differential weathering
Authors: Admassu, Yonathan (Kent State University, Department of
Geology, Ashtabula, OH, United States); Shakoor, Abdul; Wells,
Neil A.
Source: Engineering Geology, January 04, 2012, Vol. 124, pp. 1­11
Publisher: Elsevier : Amsterdam, Netherlands
Country of Publication: Netherlands
Publication Date: January 04, 2012
Collation: 11 p. 1­11
Conference: English
Languages: (30)Engineering geology
Major Categories: differential weathering;durability;geologic hazards;mass
Subject(s): movements;natural hazards;Ohio;regression analysis;roads;rock
masses;rock mechanics;rockfalls;slope stability;soft
rocks;statistical analysis;stress;United States;weathering
Abstract: One of the most important considerations in designing cut slopes
in sub­horizontal, inter­layered, sedimentary rocks subject to
differential weathering is predicting the total depth of undercutting.
Undercutting­induced rockfalls are a major problem for many
roadways in Ohio. The total depth of undercutting was measured
for 59 profiles from 18 cut slope sites in Ohio with references to
cut faces of hard rock units containing pre­split blast­hole traces.
The presence of blast hole traces ensured that the rock face
represented the slope surface that was cut during construction.
Additionally, initial design plans were used for reference. Step­
wise regression was used to determine the geological,
geotechnical, and geometrical factors that have the highest
influence on the total depth of undercutting. Selected independent
factors used in the regression analysis included the vertical
distance of the undercut unit from the slope crest, the relative
position of the undercut unit from the slope crest, the total
thickness of the undercut unit, the spacing of orthogonal joints
within the undercut unit, the slake durability index value of the
undercutting unit, the initial slope angle, and the age of the road
cut. Factors that showed the most significant correlation with the
total depth of undercutting were found to be the vertical distance
of the undercut unit from the slope crest, the relative position of
the undercut unit from the slope crest, the total thickness of the
undercut unit, joint spacing within the undercut unit, and the slake
durability index of the undercutting unit. The regression analysis
http://web.b.ebscohost.com/ehost/delivery?sid=6245f5f6­303a­4e12­a37d­c65fd3d57dbf%40sessionmgr113&vid=11&hid=118&ReturnUrl=http%3a%2f%2fweb.b.… 1/2
3/24/2016
EBSCOhost
resulted in an R (super 2) value of 0.61, with the depth of
undercutting correlating most strongly with a closer relative
position of the undercut unit to the slope crest above it and to a
closer spacing of orthogonal joints within the undercut unit. These
results can be attributed to the fact that more porous and fractured
rock units closer to the slope crest intercept and transport greater
amounts of infiltrating groundwater, producing greater depths of
undercutting. Also, closely jointed rock units are more permeable,
allowing more groundwater seepage, which also leads to greater
undercutting.
General Notes: Based on Publisher­supplied data
Illustrations: illus.
Publication Type: Serial
CODEN: EGGOAO
ISSN: 00137952: Print
Reviewed Item: Analytic
URL: Series: http://www.sciencedirect.com/science/journal/00137952
DOI: 10.1016/j.enggeo.2011.09.007
Copyright: GeoRef, Copyright 2012, American Geosciences Institute.
Reference includes data from CAPCAS, Elsevier Scientific
Publishers
Update Code: 201227
Accession Number: 2012­051610
Database: GeoRef
http://web.b.ebscohost.com/ehost/delivery?sid=6245f5f6­303a­4e12­a37d­c65fd3d57dbf%40sessionmgr113&vid=11&hid=118&ReturnUrl=http%3a%2f%2fweb.b.… 2/2