THESIS APPROVAL The abstract and thesis of Susan L. Bednarz for the Master of Science in ...

136 Pages·2009·7.64 MB·English

THESIS APPROVAL
The abstract and thesis of Susan L. Bednarz for the Master of Science in
Geology were presented May 29, 2002, and accepted by the thesis committee
and the department.
COMMITTEE APPROVALS: ____________________________________
Michael L. Cummings, Chair
____________________________________
Georg H. Grathoff
____________________________________
Scott F. Burns
____________________________________
Trevor D. Smith
Representative of the Office of Graduate
Studies
DEPARTMENTAL APPROVAL: ____________________________________
Michael L. Cummings, Chair
Department of Geology
ABSTRACT
An abstract of the thesis of Susan L. Bednarz for the Master of Science in
Geology presented May 29, 2002.

Title: Influence of Halloysite on the Engineering Behavior of Basaltic Saprolites
in Northwestern Oregon and Southwestern Washington.
Saprolite is commonly developed on Tertiary basalt in northwestern
Oregon and southwestern Washington. Basalt saprolites are often sensitive, in
that they release water and lose shear strength when disturbed. Non-sensitive,
featureless residual soil mantles sensitive basalt saprolites.
Borehole samples of extrusive basalt and intrusive basalt (diabase)
saprolites from six study sites in northwestern Oregon were analyzed using X-
ray diffraction and scanning electron microscopy (SEM). Clay mineral zonation,
observed in borehole samples obtained on Mt. Scott in southeast Portland,
Oregon, show that 10Å halloysite is most abundant near the bedrock contact,
7Å halloysite is most abundant toward the middle to upper portions of the
saprolite, and kaolinite is most abundant in the residual soil. Zonation of
smectite is unclear. Interlayered halloysite/expandable clay is identified in
almost all saprolite samples analyzed but not in the overlying residual soil
samples.
Laboratory and field testing can be used to identify sensitive saprolites
prior to construction. Sensitive saprolites have high natural water contents
(generally >50%), low dry densities (5.7 to 6.4 kN/m3), Atterberg limits
and moisture/density relationships that vary with drying and remolding, and
release water when compressed.
Engineers have linked soil sensitivity in saprolites to the presence of
water-filled, hydrated (10Å) halloysite tubes that are crushed during
construction, adversely affecting stripping, placement, and compaction.
Although 7Å halloysite is found in all sensitive saprolites analyzed within the
study sites, 10Å halloysite is not ubiquitous to these soils. The water released
during compression of sensitive soils is stored in boxwork voids (identified by
SEM analysis) and not inside individual halloysite tubes. The loss of sensitivity
in surficial residual soil is due to the breakdown and collapse of the boxwork
voids within the saprolite due to pedogenic processes.
INFLUENCE OF HALLOYSITE ON THE ENGINEERING BEHAVIOR OF
BASALTIC SAPROLITES IN NORTHWESTERN OREGON AND
SOUTHWESTERN WASHINGTON

by
SUSAN L. BEDNARZ

A thesis submitted in partial fulfillment of the
requirements for the degree of
MASTER OF SCIENCE
in
GEOLOGY
Portland State University
2002
ACKNOWLEDGMENTS
Many thanks to the following individuals who provided information,
assistance, and advice towards the completion of this research: Michael
Cummings, Georg Grathoff, Scott Burns, and Sherry Cady, Portland State
University; Jim Maitland and Tim Pfeiffer of Foundation Engineering, Inc.; Derek
Cornforth, Charlie Hammond, and Brent Black of Cornforth Consulting; Jim
Griffith of the US Army Corps of Engineers; Reka Gabor, Portland, Oregon;
Reed Glasmann of Oregon State University; David Rogers of University of
Missouri, Rolla; Michael Williams of the Washington Department of
Transportation; Clackamas County Department of Transportation and
Development; Wayne Isphording, University of South Alabama. I would also
like to thank the Clay Minerals Society for providing a grant to fund this
research.
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TABLE OF CONTENTS
ACKNOWLEDGMENTS ........................................................................................ i
TABLE OF CONTENTS ........................................................................................ ii
LIST OF FIGURES ............................................................................................... vi
LIST OF TABLES ................................................................................................ vii
INTRODUCTION .................................................................................................. 1
BACKGROUND .................................................................................................... 3
GEOLOGIC SETTING .......................................................................................... 9
LOCAL ENGINEERING CASE HISTORIES ...................................................... 17
Mud Mountain Dam ....................................................................................... 17
Toutle River Sediment Retention Structure .................................................. 18
Trask River Dam Raise ................................................................................. 19
Hills Creek Dam ............................................................................................ 21
Spirit Lake Memorial Highway ...................................................................... 22
H3 Tunnel, Oahu, Hawaii .............................................................................. 23
STUDY SITES .................................................................................................... 24
Monterey Avenue Overcrossing, Southeast Portland, Oregon .................... 24
West Salem Site 1, Oregon .......................................................................... 25
West Salem Site 2, Oregon .......................................................................... 25
Carlton, Oregon............................................................................................. 26
Silverton, Oregon .......................................................................................... 26
South Salem, Oregon ................................................................................... 27
ii
METHODS .......................................................................................................... 28
Field Sampling Methods ............................................................................... 29
Field Soil Sensitivity Testing ......................................................................... 30
X-Ray Diffraction Analysis ............................................................................ 30
X-ray Diffraction Analysis of -2μm Material ............................................. 31
X-ray Diffraction Analysis of Bulk Samples ............................................. 33
Toluidine Blue Treatment .............................................................................. 33
Magnetism ..................................................................................................... 34
Scanning Electron Microscopy ..................................................................... 35
Engineering Index Testing ............................................................................ 36
RESULTS ........................................................................................................... 37
X-Ray Diffraction Analysis Overview ............................................................ 37
X-Ray Diffraction Sample Data Summary .................................................... 39
Monterey Overcrossing Borehole BH-3 .................................................. 39
Monterey Overcrossing Borehole BH-7 .................................................. 41
Monterey Overcrossing Borehole BH-10 ................................................ 43
Monterey Overcrossing Borehole BH-18 ................................................ 45
Monterey Overcrossing Borehole BH-27 ................................................ 46
Monterey Overcrossing Borehole BH-43 ................................................ 47
West Salem Site 1 Borehole BH-1 .......................................................... 47
West Salem Site 2 Borehole BH-1 .......................................................... 48
Carlton Boreholes BH-1 and BH-2 .......................................................... 48
iii
Silverton Borehole BH-1 .......................................................................... 49
South Salem Borehole BH-2 ................................................................... 49
Magnetism Observations .............................................................................. 50
Field Sensitivity Testing Results ................................................................... 51
Testing for Amorphous Clay (Allophane and Imogolite) ............................... 52
Scanning Electron Microscopy (SEM) Results ............................................. 52
Engineering Index Testing Results ............................................................... 62
DISCUSSION ..................................................................................................... 64
Clay Mineralogy in Basaltic Saprolites and Residual Soil ............................ 64
Clay Zonation .......................................................................................... 64
Mixed-Layered Halloysite/Expandable Clay ........................................... 67
Desiccation of 10Å Halloysite .................................................................. 70
Development of Sensitivity in Basaltic Saprolites ......................................... 70
Occurrence of Sensitive Saprolites in Other Volcanic Rocks ....................... 74
Identification of Sensitive Volcanic Saprolites .............................................. 75
Field Index Testing .................................................................................. 75
Engineering Index Testing ....................................................................... 76
X-Ray Diffraction Analysis ....................................................................... 78
Mitigation of Sensitive Volcanic Saprolites ................................................... 78
CONCLUSIONS ................................................................................................. 80
FUTURE WORK ................................................................................................. 84
LITERATURE CITED ......................................................................................... 85
iv
v
APPENDICES
A Oregon and Washington Case Histories of construction in Sensitive
Volcanic Saprolites…………………………………………………………94

B Engineering Test Procedures and Data…………………………………113
C Study Area Sample Descriptions………………………………………...119
D X-ray Diffraction Analysis…………………………………………………139
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