the influence of temperature, carbon content, and
TRANSCRIPT
Scholars' Mine Scholars' Mine
Masters Theses Student Theses and Dissertations
1971
The influence of temperature, carbon content, and preloading on The influence of temperature, carbon content, and preloading on
secondary consolidation of a clay secondary consolidation of a clay
Richard Kai-Ming So
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THE INFLUENCE OF TEMPERATURE, CARBON CONTENT,
AND PRELOADING ON SECONDARY CONSOLIDATION OF A CLAY
BY
RICHARD KAI-MING SO, 1942-
A THESIS
Presented to the Faculty of the Graduate School of the
UNIVERSITY OF MISSOURI-ROLLA
In Partial Fulfillment of the Requirements for the Degree
MASTER OF SCIENCE IN CIVIL ENGINEERING
1971
ii
ABSTRACT
The effect of temperature, organic carbon content,
and preloading on secondary consolidation of Bryce clay
has been studied. A straight line plot of void ratio
versus logarithm of time was established in secondary
consolidation for long term loading periods up to one
month. Temperature changes within the range of S°C.
to 4S°C. were studied in the secondary consolidation
phase at different stress levels and different carbon
contents of the soil. Secondary consolidation in a
preloading cycle at a stress level of 2 tsf unloaded
to 1 tsf and reloaded to 2 tsf was studied. The pre
loading tests were at temperatures of S°C., 2S°C., and
4S°C. on samples of varying carbon contents.
It was found that the value of Ca (secondary con
solidation rate expressed as the void ratio per cycle
of logarithm of time) could be reduced by preloading at
a constant temperature. At higher effective stresses,
Ca was found to be dependent on the carbon content of
the soil at 2S°C. and 4S°C., and under the same condi
tions, Ca was independent of the carbon content at 5°C.
At a given temperature a value of Ca was established.
If the temperature was increased for a period of time
and then lowered to the original temperature, the final
en was considerably less than the original Ca. If the
temperature was decreased between a given initial and
final temperature, it was found that C was only ~
slightly affected.
iii
iv
ACKNOWLEDGEHENT
The author wishes to express his gratitude to
Dr. Norbert o. Schmidt for his many helpful suggestions,
guidance, and encouragement during the preparation of
this paper. Acknowledgement is also due Professor
John B. Heagler for his valuable suggestions and con
structive criticism on this paper. Author is indebted
to Mr. Stanley Notestine for his proof reading and
editing of this paper and to Mrs. Judy Notestine who
has ably and patiently typed the manuscript.
v
TABLE OF CONI'ENTS
ABSTRACT e 1 1 I I I I 1 I 1 1 I t I I I I I I I I I I I I I I I I I I I I t I I I I I I I I I I ii
ACKNOWLEDGEMENT I I I I I I I I I I I I I 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 iv
LIST OF FIGURES I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I vii
LIST OF TABLES I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I ix
Chapter I. INTRODUCTION I I I I I I I I I I I I I I I I I I I I I I I I I I I 1
Chapter II. LITERATURE REVIEW I I I I I I I I I I I I I I I I I I I I I 4
A. General I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I 4
B. Temperature E~~ect on Secondary Consolidation •..•••..•.•••••••..••• . . . 8
c. Preloading and Carbon Content E~~ect on Secondary Consolidation .••••••••.•• 10
Chapter III. PROCEDURE I I I I I I I I e I I I I a I I I I I I I I I I I I I I 13
A, Soil Description I I I I I I I I I I I I I I I I I I I I I I 13
B. Soil Preparation • • • • • • • • • • • • • • • • • • • • • • 13
c. Design o~ Equipment I I I I I I I I I I I I I I I I I I I 16
D. Testing Procedure I I I I I I I I I I I I I I I I I I I I I 20
E. Testing Program I I I I I I I I I I I I I I I I I I I I I t I 20
Chapter IV. SECONDARY CONSOLIDA'riON TEST RESULTS AND DISCUSSION I I I I I I I I I I I I I I I I I I I I I ... 23
A. Test Results and Analysis • • • • • • • • • • • • • 23
B. Discussion I I I I I I I I I I I I e e e e e e • e e e • e e e e e 39
Vi
Chapter v. SUMMARY AND CONCLUSIONS • • • • • • • • • • • • • • • •
Chapter VI. RECOMMENDATION FOR FUTURE RESEARCH • • • • 52
BIBLIOGRAPHY I I I I I I I I I I I I I I I I I I I I I I I I I I I I I • I I I I I I I I I I .54
VITA • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • 58
Vii
LIST OF FIGURES
Figures Page
1. Compressibility o~ Clay Exhibiting Delayed Consolidation (a~ter Bjerrum, 1967) •.••••••••... 6
2. E~rects o~ Stress Unloading on Secondary Compression Laboratory Tests (a~ter Johnson, 1970) ..•••••••.•..••••..••.••...••...•. 11
3. Front View or Loading Frame with Polystyrene Insulated Cell and Consolidometers •..••.••...... 18
4. Temperature Controlled Consolidometer Cell...... 19
5. Typical Result of Long Term Test................ 24
6. Erfect of Temperature Decrease on High Carbon Content Soil ................• , .. , .............. , 26
7. Effect of Temperature Increase on High Carbon Content Soil ......................... , , . . . . . . . . . 27
8. E~fect of Stress Level and Carbon Content on C at 4 5°C ..........•.... , .......•.............. ~ , .
9. Ef~ect o~ Stress Level and Carbon Content on C~ at 25°C ·····••••••••••••••••••••••••••••••••••••
10. E~~ect o~ Stress Level and Carbon Content on C at 5 oc ....... , ............................... <; , •
11. E~fect o~ Carbon Content and Temperature on C~ for Reloading at 2 tsr ....••.••..••.•...........
12. E~~ect o~ Reloading on Secondary Consolidation ..
13. Ef~ect o~ Temperature Increase and Return on Intermediate Carbon Content Soil at High Stress
29
30
31
32
34
Level ... , ...... , . , .... , . . . . . . . . . . . . . . . . . . . . . . . . . 35
14. E~~ect o~ Temperature Increase and Return on High and Low Carbon Content Soils............... 36
15. E~~ect o~ Temperature Decrease and Return on High and Low Carbon Content Soils............... 37
viii
Figures Page
16. Viscosity of Water at Various Temperatures at 1 Atmosphere (after Dorsey, 1968} .•••.••••••.••• 44
17. Effect of Temperature Increase and Return on Intermediate Carbon Content Soil at Low Stress Leve 1 . . . . . . . . . . . . . . . . • . . . . . • . . . • • . . . . • . • . . • . . . . . 47
LIST OF TABLES
Tables
1. Physical Properties o~ Bryce Clay Loam and H2o2 Treated Bryce Clay .••.•........•••.••.•
2. Testing Program •....•.••...•....••.......•..
1x
Page
14
22
c~n~ I
INTRODUCTION
Due to the pressure o~ population more and more
sites with poor subsoil conditions are being utilized
for construction. For any structure built on poor
subsoil, three foundation questions are always of basic
interest. The first is the factor of sa~ety against a
catastrophic ~oundation failure. The second is the
amount of settlement that can be expected. The third
1
is the amount of time required for this settlement to
take place. The theory of consolidation attempts to
answer these last two questions. For highly compressi
ble soils, secondary consolidation may be vitally im
portant because primary consolidation may occur in a
short time, perhaps even as the building loads are
applied to the soil. In this investigation particular
attention is given to the ef~ect of temperature, organic
content of the soil, and preloading on secondary consoli
dation.
Organic soil is thought to be a weak and highly
compressible soil. It has a lower unit weight, higher
liquid limit, and is darker in colour than inorganic
soils. Schmidt (1965) showed that hydrogen peroxide
treatment removed organic matter without affecting the
physical properties of the mineral fraction of the soil.
The organic content can thus be isolated as a factor 1n
2
controlling soil properties.
Comparatively little attention has been given to
the relationship between laboratory temperature and
actual rield temperature, and its effect on soil pro
perties. Temperatures above normal are often found under
the foundations of power plants and some factories, while
low temperatures are found under the foundations of
refrigerated warehouses. Climatic conditions can afrect
all soils in a given locale. It has been shown in
general, that changing the temperature can affect the
strain-time relationship in secondary consolidation
(Leonarda, 1962r Mitchell, 1969: Hahibagahi, 1969).
If loads are light to moderate and relatively
uniform, shallow foundations are normally more economi
cal than other alternatives such as excavation and back
fill, a deep foundation, or special subsoil treatment.
For poor subsoil conditions, preloading may be a signi
ficant way to control settlement. Control of tempera
ture may be another way, The organic carbon content
may strongly influence both of these factors. Tempera
ture, organic content, and the preloading effect on
secondary consolidation have been studied in this
research.
Organic A horizon Bryce soil and the same soil
treated with hydrogen peroxide to remove the organic
matter have been used in performing the temperature
controlled consolidation tests. Soil samples are
3
consolidated until the straight line portion of secondary
consolidation is developed in the void ratio versus
logarithm of time plot. After the samples were in the
secondary compression phase, in part of the tests the
temperature was either raised or lowered in the consoli
dometer for several days until a new curve was defined.
Then the temperature was returned to the original temp
erature. The stress-strain-time relationship effect of
changing temperatures in secondary consolidation has
been studied.
A. General
CHAPI'ER II
LITERATURE REVIEW
Consolidation is the vertical compression of a
4
soil caused by the escape of porewater due to an applied
load. Terzaghi (1925) published a mathematical theory
of consolidation which is based on some simple assump
tionss the voids of the soil are completely filled with
waterr both the water and the solid constituents of the
soil are perfectly incompressible• Darcy's law is validJ
the coefficient of permeability, k, is a constanta and
the time lag of consolidation is due entirely to the
low permeability of the soil. There are many cases
reported (e.g., Leonarda and Ramiah, 1959; Lo, 1961) in
which the time-settlement relationship of a clay investi
gated in the oedometer and in the field could not fully
be explained by the simple Terzaghi theory. This is
referred to as secondary consolidation and is generally
considered to occur under a constant effective stress.
It is most manifest when primary consolidation is com
plete, whereas in the primary consolidation phase the
void ratio decrease is due to the progressive dissipation
of pore pressure within the soil voids. In the Terzaghi
consolidation theory, only the seepage resistance is
considered to retard the transition of the grain
skeleton into a new equilibrium condition under the
total stress state. The structural resistance is
neglected. Clearly in cohesive soils, the attraction
force acting between the bonds which hold together the
atoms of a clay mineral have to be overcome.
5
According to Tan (1957), instantaneous and retarded
deformation are the two main stages of deformation in
a typical flow curve of a clay. The instantaneous
deformation may be due to flexure of the thin plate-
like clay particles and/or to an increase of repulsion
between the clay particles. The retarded deformation
is suggested to be due to the visco-elastic properties
of the clay particles and to the migration of water
molecules. Tan also explained the mechanism of secondary
consolidation as the jumping at the contacts of electro
static bonds of a card-house structure.
Bjerrum (1967) used a system of parallel curves
inane log p diagram (illustrated in Fig. 1) to describe
the compressibility characteristics of a clay showing
secondary consolidation. Each line represents an
equilibrium void ratio for different values of effective
pressure at a specific time of sustained loading. The
lines are slightly curved, and curvature decreases with
increasing pressure. A vertical line represents the
delayed compression which largely consists of secondary
compression (void ratio decreases at constant effective
stress), the length of the vertical line increases
linearly with time under a constant effective pressure.
6
1 . .5 -Sedimentation
Compression
1.4
0 Additional .... ~ Loading cxs 0::
rd l.J ..-f 0 :> Equilibrium
Void Ratio at Diff. Time of Sustained Loading
1.2
J Days J Years JO Years JOO Years JOOO Years
1.1 4 6 8 10 12 1.5 20 JO
Vertical Pressure t/m2 (log scale)
FIGURE 1. Compressibility of a Clay Exhibiting Delayed Consolidation (after Bjerrum, 1967).
If the clay is subjected to further loading by an
additional vertical stress which does not exceed the
critical pressure, Pc, only a small decrease in void
ratio occurs. If the additional load is so large that
the effective stress exceeds Pc' only that part of the
load exceeding Pc will produce a large instant settle
ment. Figure 1 shows a unique relationship between
void ratio, pressure, and time.
7
On the basis of the results of long term observations,
Buisman (1936) established a linear relationship between
void ratio plotted on an arithmetic scale versus time
plotted on a logarithmic scale for secondary consolida
tion. This relationship was introduced when dealing with
consolidation without seepage resistance. In cases when
primary consolidation is mainly governed by Terzaghi's
theory, secondary consolidation is described by the
logarithmic relationshipJ and the two branches of the
consolidation curve can be separated by the logarithm
of time fitting method as suggested by A. Casagrande
(1936).
Many others have reported the linearity of secondary
consolidation on a logarithmic time plot (Leonarda and
Altschaeffl, 1964, Barden, 1969r Mitchell, 1969). Others
have reported that the plot may not be linear (Lo, 196la
Wahls, 1962). Lo argued that if linearity continued
indefinitely a sample would consolidate to nothingness.
By postulating a sample based on rheological
models described in mathematical terms, Barden (1969)
suggests all mechanisms are compatible with rheological
models by simply considering a linear spring with a
non-linear dashpot, provided a suitable expression for
the non-linear dashpot can be formulated.
8
Buisman (19)6) said that C , the slope of secondary a consolidation line of a void ratio versus logarithmic
time plot, was proportional to the applied load.
Newland and Allely (1960) found that the slope of the
secondary plot was independent of the load increment
ratio, the consolidation pressure, and the thickness of
the sample. Green (1969) agreed with Newland and Allely's
conclusions for the Bryce clay that he studied. For
light loads, Wahls (1962) found an initial rapid increase
in Ca with decreasing void ratio until a given value of
Ca was attained. Thereafter, with further decrease in
void ratio, Ccr decreased slightly. Wahls concluded that
C was a function of void ratio, hence of effective stress. a
Lo (1961) said that vibration is another disturbing
factor and can cause an instantaneous volume reduction
in the secondary consolidation phase. Bjerrum (1964)
agreed with Lo; he mentioned that a cyclic load caused
additional compression of the sample.
B. Temperature Effects on Secondary Consolidation
Gray (19)8) investigated remolded samples of
organic silty clay and found a shift in the location of
the recompression curve with a change in temperature.
According to Finn (1951) temperature had no significant
effect on void ratio. Matlock and Dawson (1951)
9
supported Finn's statement by asserting that ordinary
temperature variations had unimportant effects on the
void ratio-pressure curve, but did influence permeability.
However, the result of altering the temperature of the
consolidation test during the secondary consolidation
phase indicated that an increase in temperature resulted
in a higher rate of secondary consolidation (e.g., Gray,
1936r Lo, 196lr Schiffman, et al., 1966).
Kaul (1963) studied the effect of temperature on
secondary consolidation by performing a series of con-
solidation tests, with each sample at a different con-
stant temperature. No definite conclusions were drawn
from the results of Ca at different temperatures. Schmidt,
et al, (1969) found that Ca was influenced by temperature,
but the degree of influence was dependent on the stress
level. Hahibagahi (1969) found that the Ca for organic
Paulding soil increased with increasing temperature, but
only for overconsolidated samples. The C was independent a
of the testing temperature for normally consolidated
samples. For normally consolidated or overconsolidated
inorganic Paulding soil, Ca remained fairly independent
of the testing temperature.
C. Effect of ?reloading and Carbon Content on Secondary Consolidation
Hanrahan (1954) found that the secondary consoli
dation of peat could be reduced by preloading. But
Barber's (1961) laboratory tests on organic silt showed
that preloading had little effect on the long-time rate
of secondary consolidation. Leonarda and Ramiah (1959)
showed that under the condition of one-dimensional con-
solidation moderate surcharges acting for comparatively
short periods of time and then removed was effective in
reducing secondary compression. Jonas (1964) observed
no secondary settlements after the partial unloading of
an organic silty clay in the field, confirming Leonarda
and Ramiah's and Hanrahan's work. Simons (1965) agreed
and mentioned that the longer the surcharge was allowed
to act, the smaller the secondary consolidation.
10
Johnson (1970) shows an illustration of the effect
of unloading on laboratory behavior in secondary com-
pression (Fig. 2). For a period of time after partial
unloading, little or no secondary compression is evident,
but thereafter secondary compression appeared at a
reduced rate as compared to a test in which there was
no unloading. The greater the magnitude of the tempor-
ary surcharge the greater was the time interval following
removal of the surcharge load during which little second-
ary compression occured. When secondary compression
reappeared, Ca was less than before the surcharge stress
I 0 .... ~ aS 0::
00 .... 0 :>
Primary Consolidation Secondary Consolidation
Time For Reappearance of Secondary Compression Increase With Increased Amount of Stress Unload----~
Little or No Sec. Com~
~~ --o~-o~o----
""'- --~ ~ '-......... tsr ~
Sec. Compr. With Increasing Magnitude of Stress Unloading at Tlme t 8 r
Log Time
FIGURE 2. Effects of Stress Unloading on Secondary Compression Laboratory Tests (after Johnson, 1970), .......
.......
was applied.
The quantity of organic matter in the soil has a
definite effect on secondary consolidation as pointed
12
out by Gray (19)6). He found that secondary consolidation
was a function of the type and quantity of organic matter
in the soil. Schmidt (1965) compared two soils that
differed only by organic content, and found that Ca
varied approximately linearly with organic content.
Organic matter was shown to be an independent variable.
Schmidt found that the removal of organic matter using
hydrogen peroxide had little effect on the clay minerals,
but that there was a great influence on the physical
properties of an organic soil, particularly on Ca•
due to the decrease in organic matter.
A. Soil Description
CHAPTER III
PROCEDURE
1)
The soil used ror the investigation was Bryce clay
loam to clay, (Wascher, Smith and Odell, 1951). The
sample was obtained from NW t of SW ! of Sec. 19,
T. 24, R. 1) W of Iroquois County, Illinois. (Wascher,
Alexander, Ray, Beaver, and Odell, 1960). The parent
material, to a depth of 18 inches, is mostly a dark
humic-gray soil or water deposited lake bed sediment
of the Wisconsin glacial period. It was chosen for its
high clay content and the relatively high organic
carbon content of the A horizon.
In order to study the soil behavior in the labora
tory, a large amount of homogeneous soil is needed for
use in the study. The entire testing program was con
ducted using soil obtained from a depth of 6 to 9 inches
below ground surface. In the natural state of the soil
the average organic carbon content was found to be 4.2~.
A summary of other important physical properties of the
Bryce clay is given in Table 1.
B. Soil Preparation
In general, natural samples are not homogeneous,
therefore this research has been carried out on remolded
samples.
Organic Carbon
~%)
4.2
J.O
1.9
0.9
TABLE 1
PHYSICAL PROPERTIES OF BRYCE CLAY LOA!-1
AND H2o2 ·TREATED BRYCE CLAY
Atterburg Limit Specific Particle Size Distribution LL PL PI Gravity Sand Silt Clay
> 0. 05mm 20-2u <2u
54.0 32.6 21.4 2.59 17 53 30
49.5 28.2 21.3 2.61 13 52 35
45.5 25.3 20.2 2.63 12 50 38
41.3 21.1 20.2 2.67 9 47 44
~ +=-
15
The soil was initially air dried and pulverized
by a Lancaster PC Mixer until nearly all or the soil
passed a #40 seive. Roots, dead leaves, and other
undecomposed vegetation were removed by hand before
pulverization. Of 50 lbs. of natural soil, approximately
98% passed a #40 seive. The remaining 2~ was discarded,
One half of the air dried, pulverized soil was used
without further treatment (hereafter, it will be referred
to as 4.2~ organic carbon soil). The remaining portion
was treated with hydrogen peroxide to remove most of
the organic matter to bring the organic carbon content
to about 0.9fo.
The technique of removal of substantial quantities
of organic matter without significantly affecting the
mineral fraction of the soil was developed by Baver
(1930), Schmidt (1965), and Green (1969). Over a one
hour period 100 grams of soil were added to 100 ml. of
JO% hydrogen peroxide solution in a 2000 ml. flat bottom
flask. The flask was partially immersed in a water bath
at 50°C. The soil was slowly added so as to assure that
the reaction of soil-hydrogen peroxide mixture would
not froth from the flask. Two to four hours later,
an additional 50 ml. of hydrogen peroxide was introduced.
If only a minor reaction was observed, 100 ml. of
hydrogen peroxide and 100 grams of soil were then added
over a one hour period. Two to four hours later, 150 ml.
of hydrogen peroxide was added and the flask then was
16
allowed to remain in the 50°C. water bath for 8 hours
with occasional agitation. The suspension was then
poured into an evaporating dish to air dry. The dried
soil was reground in the Lancaster mixer to pass a #40
seive. To further reduce the carbon content, the com
plete treatment was repeated. In the second treatment
series, half an hour was required for soil-hydrogen
peroxide mixing because a less strong reaction occurred.
With the Hotpack 234-4 type water bath 6 flasks could
be efficiently treated at one time.
This treatment reduced the carbon content of the
organic soil from 4.2% to 0.9%. The treated soil will
be hereafter called the 0.9% carbon soil.
In order to evaluate the effect of different
organic contents suitable proportions of the 0.9% and
4.2% carbon soils were mixed to provide a 1.9% and a
J.O% carbon soil. A listing of the physical properties
of these soils is given in Table 1.
C. Design of Equipment
Allison's wet-combustion method (1960) was adopted
to determine the carbon content of the Bryce clay. It
employs a simple apparatus and a rapid procedure of
analysis. Basically, it is an oxidation process in
which the carbon present (in a known weight of an oven
dried sample) is oxidized to carbon dioxide (Co2 ). The
sample 1s heated with potassium dichromate (K2Cr207),
17
and a digestive acid mixture made up of sulfuric and
phosporic acid is added. The evolved co2 and other
gases generated by the oxidizing acid treatment are
passed successively through a series of purifying traps,
which contain potassium iodide, silver sulfate, con
centrated sulfuric acid, zinc, and anhydrous magnesium
perchlorate. After this process, only the co2 is absorb
ed on a sorbent in a Nesbitt bulb. Quantitatively the
weight gain in the Nesbitt bulb is due solely to the
complete reaction of carbon dioxide with Mikohbite
reagent in the bulb. Knowing the weight of the original
sample and the weight gain of the Nesbitt bulb due to
the sorption of carbon dioxide, one can make a direct
calculation of the organic carbon content of the soil.
Four Clockhouse J 41 type consolidometers were
employed for this research (Fig. J). The consolidometer
rings were 2.5 inches inside diameter and 1.0 inches in
height. The deformation of the sample was measured with
a Clockhouse dial extensometer graduated with 0.0001
inches per division. In order to control the temperature
a i inch diameter copper coil was added to circle the
ring inside the circumference of each consolidometer
cell but outside the sample and ring (Fig. 4). The
coil was connected to a circulating water pump drawing
fluid from a controlled temperature water bath, thus
keeping the consolidation cell and sample at a constant
temperature. Antifreeze was added to the water bath to
18
FIGURE J. Front View of Loading Frame with Polystyrene Insulated Cell and Consolidometers
19
(a) Disassembled
(b) Assembled
FIGURE 4. Temperature Controlled Consol1dometer Cell
20
prevent freezing, as the temperature at times reached
minus J°C. Ambient temperature variations were mini
mized sincea 1) the research was conducted in an air
conditioned roomr 2) two relatively large water baths
were used (Hotpact 324-4 and Lab-line Instruments
31010-12); and 3) foamed polystyrene was cut to fit the
cells and covered the water bath for insulation.
D. Testing Procedure
The soil was mixed at a room temperature of about
25°C. to a water content slightly above the liquid limit
and allowed to cure for approximately twenty-four hours
to assure a uniform moisture content. The soil was
then reworked and brought to its liquid limit and
molded into the consolidation ring. A high vacuum
silicone grease was applied to lubricate the inside
surface of the rings. Both ends of the sample were
trimmed and the ring and soil were weighed before being
placed in the consolidometer. A small initial seating
pressure was applied to the sample for twenty-four hours.
Then the sample was ready for consolidation.
E. Testing Program
The variables 1n the testing program were tempera
ture, carbon content, and the loading schedule (Table 2).
The three temperatures used in the testing program were
5°c., 25°C. 1 and 45°C. Bryce clays with carbon contents
21
of 0.9%, 1.9%, J.O%, and 4.2% were used. All the samples
were 1.0 inches in thickness and 2.50 inches in diameter.
The loading ratio used in these tests, ~P/P, was equal
to unity. In other words, stresses were doubled with
each loading.
Bryce carbon Content
0.9%
1.9~
J.O%
4. 2~
TABLE 2
TESTING PROGRAM
LOAD INCREHENT RATIO = 1
Number of Tests at Indicated Temperature
50 250 -- --- -- - ~0
1 2 2
1 1 1
1 1 1
1 J 4
2J
CHAPTER IV
SECONDARY CONSOLIDATION TEST RESULTS AND DISCUSSION
A. Test Results and Analysis
The result of the consolidation test program is pre
sented in this chapter. The scope of this investigation
was limited to secondary consolidation. The behavior in
secondary consolidation is shown to be affected by temper
ature, organic matter, and preload1ng.
The method of separation between primary and second
ary consolidation is the logarithm of time fitting method
as suggested by A. Casagrande (1936). The remolded Bryce
soil (Table 2) was consolidated under a constant temper
ature until the straight line portion of secondary con
solidation was defined for the void ratio versus logarithm
of time plot (Fig. 5). It was found that Ca' the slope
of the void ratio versus logarithm of time plot, became
constant for each loading within approximately 5 days.
Several samples were allowed to consolidate up to one
month and no change of slope was found during secondary
consolidation. In all results of this investigation, a
straight line was the best fit for the secondary consoli
dation phase. This agrees with Leonards and Altschaeffl
(1964), Mitchell (1969), and Barden (1969). However 1n
Lo's (1961) investigation of organic and inorganic clays,
both linear and non-linear shapes of secondary consolida-
0
'" ~ ~
.725
.700
Temperature Carbon Content Normal Load
25°C. 1.9% 8 tsf
~ .675 0 >
.650
Primary Consolidation Secondary Consolidation
.625
.600~----------~----------~~--------~~~--------~~~------__j l 10 100 1,000 10,000
Time ( l1inutes)
FIGURE 5. Typical Result of Long Term Test.
N ~
25
tion were found.
Finn (1951) stated that temperature had no significant
effect on void ratio. However, in the preliminary tests
(Fig. 6), it is shown that changing the temperature from
45°C. to 25°C. in the secondary consolidation phase for
the 4.2% carbon soil C decrease to approximately zero a
at an effective stress of 4 tsf. In the secondary con-
solidation phase, temperature was one of the factors
affecting Ca. This fact had been mentioned by Gray (1936).
Lo (1961), and Schmidt, et al, (1970). If the temperature
is decreased, the void ratio versus logarithm of time
curve has the same shape as Johnson's (1970) unloading
curve (Fig. 2). For a partial unloading Johnson found
little or no secondary consolidation. It was a hypothesis
of this investigation that a decrease in temperature has
the same effect on secondary consolidation as small de-
crements of unloading.
Figure 7 shows a typical result of changing the temp
erature from 25°C. to 45°C. after the sample was in the
secondary consolidation phase. The figure also shows
the complete consolidation cycle due to the temperature
increase. This follows the conclusion of Lo (1961) and
Schiffman, et al, (1964) in showing that an increase in
temperature results in an accelerated rate of decrease
in void ratio. It was found that C at 45°C. is about a
double the value of C at 25°C. a
0 .-4 ~ aS a:
.900~
.875
Carbon Content 4.2% Normal Load 4 tsf
:s I 8 50 0 >
.825
,800 _45°C, I 25°C. _
.775~--------~~----------~~--------~~~------~~~--------~ 1 10 100 1,000 10,000
Time (Minute)
FIGURE 6. Effect of Temperature Decrease on High Carbon Soil,
1\) 0\
Carbon Content 4.2% Normal Load 4 tsf
,800
.775 0 ~
+> cd c:d
rd ~ I 750 > I
I '-
~ _ 2,2°C.
I 45°C.
.725
.700
.675~----------~----------~~--------~~~------~~~~--------~ 1 10 100 1,000 10,000
Time {r11nute)
FIGURE 7, ~ffect of Temperature Increase on High Carbon Content Soil.
N -...l
Figures 8, 9, and 10 summarize the variation of
Ca with temperature, carbon content, and stress level.
A large experimental scatter in results was found at
28
low effective stresses. However, at higher effective stress
levels, the high carbon content soil demonstrated an
obviously higher value of C at 45°C. and 25°c. than the a soils with lower organic carbon contents. The values of
C were nearly the same for different carbon content soils a
at higher effective stresses for 5°C. Green (1969) had
found that at higher effective stresses C had varied linea
arly with carbon content.
Hanrahan (1954), Leonarda and Ramiah (1959), Simons
(1965) and Johnson (1970) all agreed that secondary consoli-
dation could be reduced by preloading. In the remolded
Bryce samples, after unloading from 2 tsf, the value of C a
was found to be one-half to one-third of its value at the
same effective stress (2 tsf) before the unloading andre-
loading procedure for different carbon content soils. At
25oc. and 45°C., Ca for reloading increased with an increas
ing carbon content (Fig. 11). But C for the 0.9~ carbon a
soil had a higher value than for the 1.9~ carbon soil.
This may be due to an experimental error in the result at
5oc. or less likely some other factors rather than the
organic carbon content may have become controlling.
Clearly C can be reduced by unloading and reloading. a
However, if the temperature in the reloading stage is
-Q) a ;:: • 026 L Carbon ~ .024 Content 0
~ ,022 ~ 0 0.9% 6 1.9% .020 ,.. 0 3.0,%
Q) • 4.2% Po.! • 018
~ • 016 .-4 s:: ::> • 014 0
.-4 012 ~ . "' tl: • 010 't1 .-4 • 008 0 > - • 006
o'd • 004
.002
.000 0.25 0.50 1.00 2.00 4.00 8.00
Total Effective Stress, tsf
FIGURE 8. Effect of Stress Level and Carbon Content on ca at 45°C. l\)
"'
Carbon Content
0 0.9% 6 1.9.% 0 ).0% • 4.2%
, 0001 I I I I I I 1
0.25 0,50 1,00 2.00 4,00 8,00
Total Effective Stress, tsf
FIGURE 9. Effect of Stress Level and Carbon Content on C at 25°C, a . \.tJ 0
- .02~1 Carbon Q) Content a ..... 8
• 0221 0 0.9%
\.1
~ .o2oL 0 J.O% 0
.o18L 4.2~ ~ .n • ~ ~ .016
al .p ..... 5 .012
~ .010 .p Gi 0::
'd ..... 0 > -
0.25 o.so 1.00 2.00 .ooo - i.t.oo s.ov Total Effective Stress, tsf
FIGURE 10. Effect of Stress Level and Carbon Content on Ca at 5°C. \,..,)
~
-t1l .p
.0100 .n s::
Carbon Content
:::>
s:: .0090 .n 0 0.9% 6 1.9%
G> ,0080 El
.n E-4
0 J,O% • 4.2%
ft.-4 ,0070 0
QJ ,0060 0
~
J.4 ,0050 G>
P-1
0 ,0040 .n
.p GS 0::
"d ,OOJO .,..
0 ,0020 > -
d. 0010 0
,0000 45°
~
25 so
Temperature, C 0
FIGURE 11. Effect of Carbon Content and Temperature on C for Reloading at 2 tsf a
\.t.) l\)
JJ
increased from S°C. to 2S°C. {Fig. 12), at 2soc. is
about equal to Ctt at S°C. for the typical normally con
solidated soil. In other words, if the temperature is
increased, the Ctt in reloading may equal or exceed the
Ctt for normally consolidated samples. Therefore, the
statement that Ctt can be reduced by preloading, unloading,
and reloading should be confined to a constant temperature
condition,
From the hypothesis of the preliminary tests, tempera
ture effects as compared to loading effects in the second
ary consolidation range were studied. A series of tests
were performed as followsa (1) Ctt at one temperature was
established; {2) the temperature was raised or lowered
until a new curve was found1 {3) the sample was brought
back to its original temperature and Ctt was defined. In
this procedure it was hypothesized that an increase in
temperature simulated preloading and a decrease in temper
ature simulated unloading. The results are shown in
Figures lJ, 14, and lS.
Figure 13 shows the consolidation curve for a 1.9%
carbon soil at 8 tsf effective stress, The temperature
was increased from S°C. to 2S°C. and then decreased to
S°C. A significant decrease of Ctt was found, The Ctt
was equal to o.oo44 before the temperature increased and
dropped to 0,0018 after the temperature decrease. The
test was allowed to consolidate under the 8 tsf effective
0 ore .p
"' ~ td ore 0 >
.850
.825
.800
.775
.750 ~
Normal Consolidation
OVer Consolidation
(Preload to 2 tsf, Unload to 1 tsf, and reload to 2 tsf)
5°C. (For over
Temperature 5°C. Carbon Content 0.9%
.725 ~----------~----------~----------~----------~--------~ 1 10 100 1,000 10,000
Time (Minutes)
FIGURE 12. Effect of Reloading on Secondary Consolidation.
'$
Carbon Conuent 1.9% Normal Load 8 tsf
.675
.650 0 .,.. +> aS a=
~ ,625 0 >
,600
oc. 5°C .
. 575
· 5501 10 1oo 1,ooo 1o,ooo
Time (Hinutes)
FIGURE 13. Effect of Temperature Increase and Return on Intermediate Carbon Content Soil at High Stress Level,
\.V
""
0 .-1 ~ aS ~
1.125
1.100
Right Scale
0 6
Carbon Content Carbon Content Normal Load
0.9% 4.2% 1 tsf
. 875
.850 2S0 c • 4S0 c.l 25°C.
~ 1.075 0 Left Scale .825 >
1.050 .800
1,025 .775
1.000~----------~~------------~~----------~~~--------~~~~----~~~ 1 10 100 1,000 10,000 Time (Minutes)
FIGURE 14. Effect of Temperature Increase and Return on High and Low Carbon Content Soils,
\.tJ 0\
1.050
1. 025 t- Left Scale
0 ..-4
I -4-)
~ 0::
Right Scale
~ "" "' -,
0 !::.
Carbon Content Carbon Content Normal Load
0.9% 4.2% 1 tsf
_ 45°_Q__J _ 2 5°C J _ 4 5°C.
.875
.850
~ 1.000 ~ ~ ~ I I .825 0 :;:..
.975 .800
.950 .775
.925 10 1
A
Time (Ninutes)
FIGURE 15. Effect of Temperature Decrease and Return on High and Low Carbon Content Soils.
\N --.3
stress at 5°C. ror a one month period, during which
a constant slope ror C was obtained. This curve a
38
showed in secondary consolidation that when the testing
temperature was increased, a rapid decrease in void
ratio rollowed. Arter some time this void ratio change
slowed, and a constant value or Ca was obtained which
was greater than the Ca obtained berore the temperature
increase. Bjerrum•s (1967) (Fig. 1) investigation, pre-
viously discussed, also showed that under an additional
stress which exceeded the critical pressure, Pc• a large
instant settlement was produced. It appears to be true
that an increase in temperature has the same effect on
secondary consolidation as a small additional load which
exceeds the critical pressure. The same Figure 13 showed
that in this investigation the secondary compression ceased
when a decrease in sample temperature occured as was ex-
plained in the discussion or Figure 6.
Figure 14 and Figure 15 show the erfect of change in
temperature on Ca ror both 0.9% and 4.2% carbon soils at
1 tsr efrective stress. In Figure 14, the temperature
increase cycle was rrom 25°C. to 45°C. to 25°C. For both
0.9% and 4.2% carbon soils, which were the only ones
tested, C decreased to approximately zero. In Figure 15, a
the temperature decrease cycle was rrom 45°C. to 25°C. to
45°C., and Ca at the rinal 45°C. temperature was approxi
mately the same as ror the initial 45°C. period.
39
In both Figure 14 and Figure 15, the 4.2% carbon
soil experienced a greater rate of change o~ C« than the
0.9% carbon soil, ~rom the initial temperature to inter
mediate temperature and again ~rom intermediate tempera
ture to rinal temperature,
In addition to the above some what drastic tempera-
ture changes, small temperature increase cycles ~rom
45°C. to 50°C. to 45°C. and from 25°C. to J0°C. to 25°C.
were also studied. It was round that there was a signi
ficant decrease o~ C« ~or the 4.2% carbon soil ~rom the
initial temperature to the ~inal temperature stage, But
there was a very small or no e~fect on Ca ~or the 0.9%
carbon soil ~rom the initial temperature to the ~inal
temperature stage.
B. Discussion
Consolidation tends to orient particles into a dis
persed (or parallel) arrangement perpendicular to the
major stress. Tan (1957) postulated that deformation o~
a clay was controlled by ~lexure o~ plate-like particles,
the increase o~ repulsion between particles, the visco
elastic properties o~ particles, and the migration o~
water molecules. It is possible that there is more than
one mechanism that controls the magnitude o~ secondary
consolidation, such as bonds breaking and re~orming,
particles bending and crushing, structural breakdown,
40
visco-elastic e~~ects, and existence o~ micropores which
drain very slowly.
The secondary settlement is a consequence o~ an
adjustment o~ the particle arrangement to comply with
new sets o~ stresses. It results ~rom relative movement,
and bending and crushing o~ particles. Each time a fail
ure occurs at a contact point, a chain reaction ~ollows
with internal movement and deformations• the rate at
which this readjustment of the structure occurs is
influenced by breaking and reforming of bonds between
particles, and is also related to the adsorbed water
layer which may exert an important 1n~luence on the
visco-elastic behavior of soil-particle contact, (Bjerrum,
1964). However, on a microscopic scale, the shear
resistance of soil-particle contact must involve factors
such as dilatancy, particle bending and crushing, and
jumping of electrostatic bonds.
Clay behavior may be elastic and viscous. The viscous
behavior of clay may be due to the exchange of position
between a water molecule and a void in a bond material
containing soil particles (Murayama and Shibata, 1961).
In a water molecule the center of the positive charge and
negative charge do not coincide, and hence the molecule
behaves as a dipole. Thus water molecules may be adsorbed
on the surface of the negatively charged clay particle.
These water dipoles are strongly oriented at the surface,
41
due to the high electrical rorces attracting them to the
clay crystal surrace. As the distance of the molecule
from the surface increases, the attractive force de
creases. The degree of water molecule orientation de
creases as the disorder associated with the thermal
heating effects increases. Individual molecules may
escape from the adsorbed water layer as other molecules
take their place. The chance of an individual molecule
to leave the oriented state depends on its proximity to
the clay surface, the environmental temperature, and the
degree of coincidence of the molecular vibrations with
the direction of the applied stress at the molecular
level (Scott, 1965).
It is suggested in this research that the temperature
effect on secondary consolidation is partially governed by
the double layer theory, increasing the temperature must
lead to a decrease in the electrical potential at a
given distance. As the diffuse double layer expands due
to a temperature increase, it decreases the effective
stresses at the particle contact which permits shear
failure to occur at these contacts and also causes a de
crease in the viscosity of water, followed by an increase
in the rate of migration of water molecules. These
factors suggest why in secondary consolidation an in
crease in temperature is followed by a higher rate of
void ratio decreaseJ the equilibrium distance for the
42
double layer has decreased. The higher rate of void
ratio decrease may also be due to the effective stres•es
overcoming the bonds between the particles weakened by
the increase in temperature. The reorientation of the
particles results from relative movements such as bend
ing, crushing, and breakdown of the soil structure.
The temperature increase in the secondary con
solidation phase is followed by a complete cycle of
primary and secondary consolidation. In primary con
solidation the higher rate of void ratio decrease is
due to the breakdown of the soil structure and the
particle bonding, and to a decrease in the equilibrium
distance of the double layer. The following secondary
consolidation appears to result from the reorientation
of particles, or the breaking, reforming, and jumping of
bonds at the contacts. On the other hand, lowering the
temperature in the secondary consolidation phase, in
creases the electrical potential at a given distance
from the particle surface, and increases the effective
stresses at the particle contact which increases the
shear strength at these contacts. The viscosity of
water also increases due to the temperature decrease.
Therefore, secondary consolidation may cease, at least
temporarily, because all particles have found a stable
position.
4J
Zeevaert (1967) suggested that secondary consolida
tion obeys a micropore theory, a theory or consolidation
ror material exhibiting non-linear viscous intergranular
behavior. At the time or the soil structure consolida
tion, the non-linear viscous intergranular derormation,
or change in microscopic pore space also takes place.
Schmidt, et al, (1970) postulated that organic matter
may increase the number or micropores. Hahibagahi (1970)
mentioned that when temperature increases it is believed
to result in the rupture or organic bonds which hold the
clay particles together. When temperature increases
the micropores should drain at a raster rate. When the
temperature is lowered in secondary consolidation the
organic bonds may rerorm, the micropores must drain
more slowly under a constant errective stress. This
agrees with the observed behavior or organic Bryce soil
in comparison to inorganic Bryce soil. Tests showed
that the A horizon untreated Bryce soil was very sensi
tive to temperature.
As seen in Figure 16 the viscosity of water is quite
susceptable to temperature changes. The viscosity of
water decreases exponentially with increasing temperature.
The influence or temperature on the viscosity or the
organic material in the soil is not known, but it would
be expected that it too would decrease with increasing
temperature. It might behave very much as does asphalt.
CD tQ ..... 0 p, ..... ~ s::: CD t> .. ~ ~ ..... tQ 0 (,) fll .....
:::>
44
1.8.-------------------------------------------~
1.6
1.4
1.2
1.0
0.8
0.6
0.4
0.2
0~------~~----~~------~------~~----~~----~~ 0 0 0 100 120
Temperature, co
FIGUR~ 16. Viscosity of Water at Various Temperatures at 1 Atmosphere (after Dorsey, 1968}.
The effect of organic material in the soil has
been shown to have little recognizable effect on the
minerals in the soil, therefore its major effect should
be on surface bonding and on the adsorption character
istics of soil-water systems. The number of micropores
in the soil may also be a function of the organic con
tent, as previously stated.
The curves in Figures 8, 9, 10, and 11 indicate
that the amount of organic material has less effect on
c~ at low temperatures than at high temperatures, which
would infer that at a temperature of 5°C. the viscosity
of water could be the controlling factor. At 25°C. and
45°C. other controlling factors appear to have a major
influence on secondary consolidation.
At low effective stress levels with relatively high
void ratios, the effect of temperature and the reduction
in the viscosity of water is small relative to the other
factors controlling secondary consolidation. At high
effective stress levels with a lower void ratio, as
more structural breakdown occurs, the effect of tempera-
ture on viscosity of water may be great, and perhaps the
organic matter may flow viscously as does asphalt. The
organic bonds then may be the major factor of influence
on c~.
As the temperature of water increases from 25°C. to
45°C. its viscosity decreases about JO%. However, the
secondary consolidation data showed that C at 45°C. was ~
46
about double its value at 25°C. Between these tempera
tures, viscosity appears to be one of the major influence
factors on secondary consolidation.
For a temperature increase cycle, as S°C. to 2S°C.
to S°C .• ca decreases significantly from initial to final
temperature stage. After the temperature is returned to
the original value, C is linear on the void ratio versus a
logarithm of time plot for a long period of time. In the
case of the lower carbon content soils, the new Ca' after
the temperature increase cycle keeps its linearity on the
void ratio versus logarithm of time plot and even crosses
the extension of the line of the original ca at S°C.
(Fig. 17). This may be caused by newly oriented water
molecules in a stable condition. The behavior is
analogus to a Bingham body rather than a Newtonian type
liquid. Perhaps some of the bonds are not participating
in the movements because a threshold movement stress has
not been exceeded. This phenomenon requires further
study. A slight change in temperature and a short period
of external vibration may cause an individual molecule
to leave the oriented state. If this concept is correct,
the lower ca for S°C. should change to the original value
of Ca at 5°C. before the temperature increase cycle. The
above case occured in the lower carbon soil studied, or
in a lower temperature range such as 5°C. to 25°C. to
5°c. In lower carbon soils, or in a lower temperature
range, the increased temperature resulted in only a small
0 oM .p aS 0:::
't:l oM 0 >
Carbon Content 3.0%
1.050 Normal Load 2 tsf
1.025
1.000
o I 25o_<:[_ 5oC, "" 5 c .... --I
"""-. I
.975
.950 ...............
. 9251~--------~~--------~~------~~~------~~--------__j 10 1,000 10,000 100
Time (Minutes)
FIGURE 17. Effect of Temperature Increase and Return on Intermediate Carbon Content Soil at Low Stress Level.
~
"'
48
decrease in void ratio. The line representing en arter
the temperature increase cycle crossed the line of the
original en within one month or laboratory loading but
with no increase in en• Because of a relatively large
amount of void ratio decrease due to the temperature
increase for the higher carbon content soil in the
temperature increase cycle, a one month loading period was
not surricient time to show the C lines crossing. n
CHAPrER V
SUMMARY AND CONCLUSIONS
The purpose of this research was to study the
influence of temperature variation, organic carbon
content of the soil, and preloading on secondary con
solidation.
49
Organic A horizon Bryce soil with a carbon content
of 4.2%, and the same soil treated with hydrogen per-
oxide to reduce the carbon content to 0.9% were used
as the testing soils. Suitable proportions of the 0.9~
and 4.2% carbon soils were mixed to provide 1.9% and
J.O% carbon soils. Allison's wet-combustion method
was used to measure the carbon content. The oedometer
rings were one inch in thickness and 2.5 inches in
diameter. A load increment ratio of unity was used.
The temperature was controlled within !2°c. at 5oc.,
25oc., and 45°C. Also, a system of changes in tempera-
ture were designed to study their effect on secondary
consolidation.
Test results showed that at higher effective
stresses, the soils with higher carbon contents had
higher ca values at 25°C. and 45°C. At higher effective
stresses for samples tested at 5°C., theCa values were
nearly the same for soils with different carbon contents.
An increase in the soil temperature during the second-
ary consolidation phase resulted in a rapid decrease
50
in void ratio, ~ollowed by a C~ which was greater than
the C~ be~ore the temperature was increased, The mag
nitude o~ decrease in void ratio for an increase in
temperature in secondary consolidation is larger for
the organic Bryce soil than ~or the inorganic Bryce
soil. Decreases in the soil temperature during second
ary consolidation halted the void ratio decrease ~or a
period o~ time ~or all soils. A~ter a period of time,
secondary consolidation resumed with C~ having a reduced
value.
An increase o~ temperature in secondary consolida
tion may cause weakened bonds and a rearrangement of
particles. A similar result would occur i~ a small
additional load was added to a sample which was in the
secondary consolidation phase. Decreasing the temper
ature may cause an increase in the repulsion between
the double layer; in other words, all particles have
~ound a stable position and settlement ceases.
The viscosity o~ water is quite susceptable to
temperature changes. The in~luence o~ temperature on
the viscosity o~ the organic matter in the soil is not
known, but it would be expected that the viscosity of
organic matter decreases with increasing temperature.
These may be the two other important in~luence factors
that a~fect secondary consolidation.
The C~ can be reduced by preloading but this con
clusion should be con~ined to a constant temperature
condition. The value or Ca which was reduced by pre
loading may increase again by increasing the soil tem
perature.
51
In this research, 1t may be concluded that second
ary consolidation is not only time dependent but is
also temperature dependent, as well as stress level
and carbon content dependent.
CHAPT~R VI
RECOMMENDATION FOR FUTURE R~SEARCH
52
To better simulate field conditions, the use of
undisturbed samples ror investigation is recommended.
When using remolded samples bonds between the particles
may have been broken.
Further study or the increase in temperature on
secondary consolidation is required to predict the
field settlement rate rrom laboratory results. rr
heat could be added to the subsoil during the preload
ing operations, the length of time for preloading may
be decreased. A combined study or temperature increase,
dewatering, and preloading with application of electro
osmosis is suggested. Using electro-osmosis with pre
loading may provide better drainage conditions in the
subsoil and may also produce heat to cause a raster
rate or decrease in the void ratio. Reducing the founda
tion temperature to stop settlements for a period or
time may be an alternative way to minimize the settle
ment or certain structures where costs are not critical.
Further study in this subject should also include
the effects or vibrations on secondary consolidation.
Vibrations from an external force may increase the
degree or coincidence or the molecular vibration. It
53
may increase the probability for an individual molecule
to leave the oriented state and a more mobile state of
water molecules to be formed.
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3. bjerrum, L. (1964). International Union of Theoretical and Applied Mechanics, Rheology and Soil Mechanics, Symposium Grenoble April 1-8.
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55
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57
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29. Simons, N. E. (1965). Consolidation Investigation on Undisturbed Fornebu Clay, Norwegian Geotechnical Institute, Nr. 62.
30. Terzaghi, K. (1925). Erdbaumechanik auf Bodenphysikalischer Grundlage Deuticka, Wien, p. 339.
31. Tan, T. K. (1957). Secondary Time Effect and Consolidation of Clays, Academic Sinica, Institution of Civil Engineers and Architectural HarbinJ China, June 1957, as reported in Wahls (1962).
32. Wahls, H. E. (1962). Analysis of Primary and Secondary Consolidation, Proceedings of the American Society of Civil Engineers, Vol. 88, SM-6, pp. 207-231.
33.
34.
35.
Wascher, H. L., Alexander, J.D., Ray, B. w., Beavers, A. H. and Odell, R. T. (1960). Characteristics of Soil Associated With Glacial Tills in Northeastern Illinois, Agricultural Experiment Station, University of Illinois Bulletin 665.
Wascher, H. L., Smith, R. S., and Odell, R. T. (1951). Iroquois County Soils, University of Illinois Agricultural Experiment Station, Soil Report 74.
Zeevaert, L. (1967). Consolidation Theory for l1aterials Showing Intergranular Viscosity, Third Panamerican Conference on Soil Mechanics and Foundation Engineering, p. 89-110.
VITA
Richard Kai-Ming So, the son of Dr. Y. c. Soo and
May Szeto, was born on April 29, 1942 at Shanghai,
China.
His elementary schooling was in Nam-Si Elementary
School, Taiwan and for his high school education he
attended Sam-Yok Middle School, Clear Water Bay, Hong
Kong. He enrolled at the Hong Kong Chu Hai College in
September, 1962 and received a Bachelor of Science
58
Degree in Civil Engineering in July, 1966. He was em
ployed as an engineer with Hadi Hamouda Co., Sebha,
Libya. He came to the University of l1issouri-Rolla to
work toward a Master of Science Degree in Civil Engineer
ing in September, 1969.
He is an Associate Member of the American Society
of Civil Engineers and a Member of the International
Society of Soil Mechanics and Foundation Engineering.