Group Title: design and construction of a piezoblade and an evaluation of the Marchetti dilatometer in some Florida soils
Title: The design and construction of a piezoblade and an evaluation of the Marchetti dilatometer in some Florida soils
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Permanent Link: http://ufdc.ufl.edu/UF00097427/00001
 Material Information
Title: The design and construction of a piezoblade and an evaluation of the Marchetti dilatometer in some Florida soils
Alternate Title: The Marchetti dilatometer in some Florida soils
Physical Description: xviii, 312 leaves : ill., maps ; 28 cm.
Language: English
Creator: Boghrat, Alireza, 1950-
Copyright Date: 1982
 Subjects
Subject: Drainage -- Florida   ( lcsh )
Soil percolation -- Florida   ( lcsh )
Piezometer   ( lcsh )
Civil Engineering thesis Ph. D
Dissertations, Academic -- Civil Engineering -- UF
Genre: bibliography   ( marcgt )
non-fiction   ( marcgt )
 Notes
Statement of Responsibility: by Alireza Boghrat.
Thesis: Thesis (Ph. D.)--University of Florida, 1982.
Bibliography: Bibliography: leaves 310-311.
Additional Physical Form: Also available on World Wide Web
General Note: Typescript.
General Note: Vita.
 Record Information
Bibliographic ID: UF00097427
Volume ID: VID00001
Source Institution: University of Florida
Holding Location: University of Florida
Rights Management: All rights reserved by the source institution and holding location.
Resource Identifier: alephbibnum - 000352333
oclc - 09654318
notis - ABZ0299

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THE DESIGN AND CONSTRUCTION OF A PIEZOBLADE AND AN
EVALUATION OF THE MARCHETTI DILATOMETER IN SOME
FLORIDA SOILS





By

A icA 1h 3 v ,r nr .-,t +
A ~ ~ ub~ U *I L- ^Ji(* i- j ^ --(*


A DISSERTATION PRESENTED TO THE GRADUATE COUNCIL OF
THE UNIVERSITY OF FLORIDA
IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE
DEGREE OF DOCTOR OF PHILOSOPHY











UNIVERSITY OF FLORIDA


1982




























To my dear children Pedram and Parastu














ACKNOWLEDGMENTS


The writer thanks Dr. John L. Davidson for serving

as advisor and chairman of his supervisory committee. He

is especially grateful to Dr. Davidson for his skillful

guidance in the prepaiatiuion of this diti iu~ruiL and

for the advantages of his competence and practical experi-

ence. The writer is appreciative of the assistance given

him by the members of his supervisory committee throughout

this program: Dr. James H. Schaub, Dr. Frank C. Townsend,

Professor Walter H. Zimpfer and Dr. James L. Eades.

The writer thanks Dr. Silvano Marchetti for all his

advice and counseling during the year he was at the

University of Florida as a visiting professor. He acknowl-

edges the value of Dr. Marchetti's many ideas and sugges-

tions in the early stages of the research.

The author is grateful to Professor David W. Gibson

for his support and contribution during the stereo

photography phase of the research. He also thanks

Dr. John H. Schertmann for supplying the data reduction

computer programs for the dilatometer and cone penetration

tests.


iii







The Department of Civil Engineering and the Geotech-

nical Group are thanked for their different contributions

to this dissertation.

A special appreciation is expressed to Mr. William J.

Whitehead for his continued advice, patience, and kindness.

The writer is very grateful and thankful to his wife,

Shirley, for all of her patience and hard work which were

essential in the completing of this dissertation.

Finally, Lhe authori thaiik- his parents for the..ir

emotional and financial support during his extended absence

from them.














TABLE OF CONTENTS



Page

ACKNOWLEDGMENT..................................... iii

LIST OF TABLES.................................... ix

LIST OF FIGURES.................................... Ai

ABSTRACT........................................... xvi

CHAPTER

1 INTRODUCTION ....... ................... ...... 1

1.1 Background...... ..... ................. 1
1.2 Purpose ........................... ..... 2
1.3 Scope ............. .... ....... ......... 3

2 DESIGN OF PIEZOBLADE........................... 4

2.1 Introduction............................ 4
2.2 The Blade................................ 5
2.3 The Transducer and Connector............ 7
2.4 The Cable ............................... 20
2.5 Control and Recording Units............. 22
2.6 Calibration of the Pore Pressure
Transducer............................ ... 26
2.7 De-airing the Piezoblade................ 30

3 OTHER INSITU TEST DEVICES.................... 42

3.1 Introduction................... ... ...... 42
3.2 The Dilatometer Test.................. 42

3.2.1 The Equipment.................... 42
3.2.2 Dilatometer Test Procedure........ 44
3.2.3 Dilatometer Data Reduction........ 46

3.3 The Cone Penetration Test............... 51

3.3.1 The Equipment and Test Procedure. 51

v







Page

3.3.2 Cone Penetration Test Correlations 53

4 FIELD TESTING .. ...................... ........ 56

4.1 Introduction .... ........ ...... ........ .. 56
4.2 Test Site ................................ 56

4.2.1 Location ........................ 56
4.2.2 Site Geology ...................... 57
4.2.3 Site Plans........................ 64

4.3 Piezoblade Testing....................... 64

4.3.1 Test Preparation.................. 64
4..3.2 Tpvnp n-f Pip7znhbl1d Th t .......... 70

4.4 Dilatometer Testing...................... 71
4.5 Cone Penetration Testing................. 73

5 LABORATORY SOIL TESTS........................... 77

5.1 Introduction............................... 77
5.2 Sampling Procedures........................ 77
5.3 Tests on Disturbed Samples............... 78
5.4 Tests on Undisturbed Samples............. 81

5.4.1 Consolidation Tests.............. 81
5.4.2 Triaxial Tests.................... 88

6 STEREO PHOTOGRAPHY STUDY...................... 96

6.1 Introduction............................... 96
6.2 Equipment ............................... 97

6.2.1 Container, Probe and Sand.......... 102
6.2.2 Camera and Film................... 109

6.3 Testing Procedures........................ 112

6.3.1 Sand Placement..................... 112
6.3.2 Blade Penetration ................. 116
6.3.3 Parallax Measurements............. 116

6.4 Scale Determination, Displacements and
Strains.......................... ......... 120

6.4.1 Scales ........................... 120
6.4.2 Displacement ..................... 125
6.4.3 Volumetric Strain................. 125

vi







Page

6.5 Analysis of Stereo Photography.......... 126

6.5.1 Very Loose Sand.................. 126
6.5.2 Loose Sand... ..................... 128
6.5.3 Medium Sand...................... 128
6.5.4 Dense Sand ....................... 131
6.5.5 Very Dense Sand.................. 133

6.6 Comparison of the Dilatometer and Cone
Penetration Test Probes................. 133

7 ANALYSIS AND DISCUSSION OF RESULTS............ 137

7.1 Introduction ............................ 137
7.2 Piezcbladc R Ceults............. . ..... 137

7.2.1 Identification of High Drainage
Layers............................ 138
7.2.2 Site Uniformity.................. 139
7.2.3 Excess Pore Pressure Dissipation
Versus Soil Type.... ..... ....... 143
7.2.4 Initial Excess Pore Pressure
Versus OCR and ID................ 152
7.2.5 Comparison of Piezoblade and
Piezocone........................ 164

7.3 Dilatometer Test Results................ 166

7.3.1 Soil Classification.............. 166
7.3.2 Overconsolidation Ratio........... 171
7.3.3 Constrained Modulus.............. 177
7.3.4 Marchetti Modulus................ 179

8 SUMMARY RESULTS AND SUGGESTIONS FOR FUTURE
RESEARCH.......................... .. ......... 184

8.1 Summary. .............. ................ 184
8.2 Results ...............*.... ..... ... .... 186
8.3 Recommendation for Future Work.......... 188

APPENDIX

A PLOTS OF PIEZOBLADE TEST RESULTS............. 192

B RESULTS OF DILATOMETER TESTS................ 210

C CONE PENETRATION TEST LOGS................... 233

D CONSOLIDATION TEST RESULTS................... 246


vii







Page

E TRIAXIAL TEST RESULTS ........................ 271

F STEREO PHOTOGRAPHY ........................... 289

LIST OF REFERENCES ................................. 310

BIOGRAPHICAL SKETCH.................................. 312


viii












LIST OF TABLES


Table Page

3-1. Values of f /q for Loose Medium and Dense
Sands ..... .. ...... ... ............ ...... 55

4-1. List of Piezoblade Tests Performed......... 72

4-2. List of Dilatoimeter Tests PeLruiLmed........ 74

4-3. List of Cone Penetration Test Soundings
Performed.................................. 76

5-1. List of Undisturbed Samples Taken.......... 80

5-2. Results of Tests on Disturbed Samples from
Boring DS-1.......................... ..... 82

5-3. Results of Tests on Disturbed Samples from
Boring DS-2 .............................. 83

5-4. Results of Tests on Disturbed Samples from
Boring DS-3.. ........ ................... 84

5-5. Results of Tests on Disturbed Samples from
Boring DS-4............................. . 85

5-6. Results of Tests on Disturbed Samples from
Boring DS-5 .............................. 86

5-7. Consolidation Test Results................ 90

5-8. Triaxial Test Results................. ..... 93

5-9. Laboratory Results from Undisturbed Samples. 94

7-1. Percent Dissipation of Excess Pore Pressure
in PBT After One Minute.................. 144

7-2. Penetration Excess Pore Pressures in
Different Soils............................. 153







Table Page

7-3. Soil Classification by Laboratory Dilatom-
eter and Cone Penetration Testing.......... 168

7-4. Soil Classification by Laboratory Dilatom-
eter and Cone Penetration Testing.......... 170

7-5. OCR's from Oedometer Dilatometer Testing... 174

7-6. Constrained Moduli (M), from Oedometer and
Dilatometer Testing........................ 178

7-7. Calculation of.Dilatometer Modulus ED from
CU Triaxial Tests............... ..... ..... 180

-08. Couimiipuraui U D Values .ru m and CU
Triaxial Tests.... .............. ....... 182













LIST OF FIGURES


Figure Page

2-1. Sketch Showing Piezoblade Dimensions........ 6

2-2. Dimensions of the EPN-0350-100 Pressure
Transducer ........... ...... .. ... .......... 8

2-3. Side View of the Piezoblade Probe........... 9

2-4. Front View of Piezoblade Probe.............. 10

2-5. Location of the Transducer in the Piezoblade. 11

2-6. Piezoblade Transducer Holder................. 12

2-7. Piezoblade Showing the Transducer Cavity
and Wiring Groove............................. 13

2-8. The Transducer in Place in the Piezoblade.... 13

2-9. Piezoblade Porous Stone Holder............... 15

2-10. Front of the Piezoblade with the Porous Stone
and Its Holder............................... 16

2-11. Detail of Porous Stone Holder................ 16

2-12. The Piezoblade Connector in Place with the
Transducer and Cable Wires Attached........... 17

2-13. The Piezoblade Electrical Connector........... 18

2-14. Special Tool to Screw the Connector in Place. 19

2-15. The Piezoblade Cable .......................... 19

2-16. The De-airing Unit Holder ................... 21

2-17. The Test Control and Recording Unit........... 21

2-18. The Clamp Box................................. 23

2-19. The Control Box Circuitry.................... 24

xi







Figure Page

2-20. The Test Control Box.......... ...... ....... 25

2-21. The Voltmeter.............................. 25

2-22. The Linear Instrument Corporation Recorder. 27

2-23. The Calibration Unit....................... 28

2-24. Photograph of the Calibration Unit......... 29

2-25. Calibration Curves for Different Excitation
Voltages. .... .... ................... ..... 31

2-26. The De-airing Unit Holder.................. 34

2-27. The De-airing Unit Cylinder................ 35

2-28. The De-airing Unit Top Section............. 37

2-29. The De-airing Unit Screen.................. 38

2-30. The Assembled De-airing Unit................ 39

2-31. Photographs of the De-airing Unit's
Cylinder, Top and Screen................ 40

2-32. Photograph of the De-airing Unit and the
Piezoblade ........................... ..... 41

3-1. The Dilatometer Test Equipment.............. 43

3-2. The Flat-blade Dilatometer ................. 43

3-3. The Control Unit............................ 45

3-4. The Calibration Equipment................... 45

3-5. Dilatometer Soil and Density Evaluation
Chart ............. ................... .... 49

3-6. Begemann Tips............................... 52

3-7. Cone Penetration Test Soil Evaluation Chart. 54

4-1. Location of Alachua County and the City of
Gainesville ......................... ...... 58

4-2. Location of Lake Alice and Lake Wauberg..... 59

4-3. Topographic Map of Lake Alice............... 61

xii







Figure Page

4-4. Topographic Map of Lake Wauberg............. 62

4-5. Block Perspective Diagram of Ocala
Limestone Structure Contour Map............ 63

4-6. Site-1, North of Lake Alice................ 65

4-7. Site-2, East of Lake Alice................. 66

4-8. Site-3, West of Lake Alice................. 67

4-9. Site-4, North of Lake Alice................ 68

4-10. Site-5, Northwest of Lake Wauberg.......... 69

5-1. The Hand Auger Sampler..................... 79

5-2. The Swedish Fixed Piston Sampler........... 79

5-3. The Anteus Consolidometer ................ 87

5-4. The Soil Test (Model C-221) Consolidometer. 89

5-5. The Triaxial Test Apparatus................ 91

6-1. Stereo Image-Displaced Camera.............. 98

6-2. Stereo Image-Displaced Object.............. 99

6-3. General Two-Dimensional Displacement....... 100

6-4. Probe Penetrated in Sand................... 101

6-5. The Test Container....................... 103

6-6. Stainless Steel Dilatometer Probe.......... 104

6-7. 8/20 Edgar Sand ........................... 105

6-8. 20/30 Edgar Sand .................... ...... 106

6-9. 30/65 Edgar Sand ........................... 107

6-10. Edgar Glass Sand........................... 108

6-11.. Test Setup ................................. 110

6-12. Double Projector Anaglyphic Plotter........ 111

6-13. Tracer Point-Platen Assembly.............. 113

xiii







Figure Page

6-14. Compaction Equipment. Left-Vibratory
Compactor. Right-Constant Energy.......... 115

6-15. Jack and Extensions....................... 117

6-16. Grid Element Numbering System.............. 118

6-17. Node Point Numbering System .............. 119

6-18. Camera--Model and Projector--Stereo Image
Relationships.............................. 121

6-19. Plots of Displacement and Volumetric Strain
for Very Loose Sand ............ ............. 127

6-20. Plots of Displacement and Volumetric Strain
for Loose Sand ............................. 129

6-21. Plots of Displacement and Volumetric Strain
for Medium Sand ............................ 130

6-22. Plots of Displacement and Volumetric Strain
for Dense Sand............................. 132

6-23. Plots of Displacement and Volumetric Strain
for Very Dense Sand........................ 134

7-1. Piezoblade Profiles Across Site-1.......... 140

7-2. Piezoblade Profiles Across Site-3.......... 141

7-3. Piezoblade Profiles Across Site-5.......... 142

7-4. Percent Dissipation of Excess Pore Pressure'
Versus ID for Different Soils.............. 149

7-5. Percent Dissipation of Excess Pore Pressure
Versus ID for Different Soils
(ID = log scale)........................... 150

7-6. Penetration Excess Pore Pressure Versus
OCR for Sand and Silty Sand................. 159

7-7. Penetration Excess Pore Pressure Versus
OCR for Sandy Silt......................... 161

7-8. Penetration Excess Pore Pressure Versus
OCR for Silt..................... .......... 162


xiv








Figure Page

7-9. Penetration Excess Pore Pressure Versus
OCR for Clayey Silt........................ 163

7-10. Penetration Excess Pore Pressure Versus
OCR for Silty Clay and Clay................ 163

7-li. Plots of Excess Pore Pressure Versus Depth
from Piezocone and Piezoblade Sounding at
Site-1 . . . . . ... ..................... . 165

7-12. Typical Profiles of KD Versus Pv for
Uncemented Cohesive Soil in Simple
Unloading......................... ......... 173

7-13. Correlations between OCR and KD, Tncluding
Florida Data.............................. 176

7-14. Plots of ED Versus AP ...................... 183













Abstract of Dissertation Presented to the Graduate Council
of the University of Florida in Partial Fulfillment of the
Requirements for the Degree of Doctor of Philosophy



THE DESIGN AND CONSTRUCTION OF A PIEZOBLADE AND AN
EVALUATION OF THE MARCHETTI DILATOMETER IN SOME
FLORIDA SOILS

By

Alireza Boghrat

December, 1982

Chairman: Dr. John L. Davidson
Major Department: Civil Engineering

The primary purpose of the research was to develop

a better understanding of the Marchetti flat-plate

dilatometer, especially with regard to the test drainage

conditions and the experimentally derived correlations.

To evaluate the drainage conditions around the

dilatometer, a new insitu testing device, identical in

shape but measuring only pore water pressures, has been

designed and constructed. It consists of a thin steel

blade with a flush mounted porous cap and an internal

pressure transducer. This piezoblade is pushed into the

ground and the pore pressures measured and recorded on a

strip chart recorder.

A program of field testing was carried out at five

sites near the University of Florida campus. Standard

xvi







dilatometer tests and piezoblade soundings, in which the

probe was penetrated in 20 cm increments with a one

minute or more delay between steps, were performed

adjacently. The incremental piezoblade insertion was

to simulate the dilatometer test procedure. From an analy-

sis of the sounding results, a plot was developed of percent

dissipation of excess pore pressure versus soil type. This

gives a quantitative measurement of the drainage conditions

(dran- p partially drained, undrained) during dilatometer

testing in any soil.

In addition to the dilatometer and piezoblade soundings

at each site, cone penetration tests were performed and

disturbed and undisturbed samples recovered for laboratory

testing. A comparison of the dilatometer and the labora-

tory test results allowed an evaluation of the Marchetti

correlations which were developed for soils in Italy. It

was found that the dilatometer very accurately identified

the soils through which it was penetrating. The existing

parameter correlations, however, overpredicted both the

overconsolidation ratio and the constrained modulus and

underpredicted the Young's modulus. Correlations better

suited to these particular Florida soils were developed.

A laboratory study was performed to compare the

disturbance effects surrounding penetrated blade and

cone-shaped probes. This was carried out in dry sand

using a stereo photography technique to accurately measure

xvii








grain displacement in the vicinity of the probe. The

dilatometer-shaped probe was found to cause much less

disturbance of the soil than the standard cone penetra-

tion test tip.


xviii












CHAPTER 1

INTRODUCTION


1.1 Background

Soil is an integral part of most civil engineering

structures. For many, soil provides the foundation support.

Soil is used in many projects as a construction material,

e.g., earth dams, fills, reclamation projects and in

highways and airfields. Soil interaction with the struc-

ture is important, e.g., in tunnels, pipes, underground

structures, retaining walls and excavations. Other soil

behavior such as slope stability, shrink-swell potential,

freeze-thaw properties, behavior during earthquake or

vibrations or potential for the storage of industrial

fluids may be important.

For any structure which is to be properly designed,

the extent, variability and properties of the soil must

be known. The traditional means of obtaining these has

been to make a boring, recover samples and perform

laboratory tests. In the past decade, however, there has

been a rapidly growing interest within the geotechnical

profession in the insitu determination of soil properties.

In such a determination, a device is inserted into the

ground, the test performed and the soil properties

calculated, usually by means of an experimentally derived

1





2

correlation. Some of the advantages of insitu testing are

1. They are performed in the natural environment

and under natural conditions with the correct

moisture and stress regimes.

2. Disturbance is much reduced since sampling,

handling, transportation and specimen preparation

are eliminated.

3. Compared to most laboratory tests, insitu testing

time is shorter.

4. The cost of insitu testing is normally less,

relative to the quantity of data acquired.

Many different insitu testing devices have been

developed, often for the determination of a single soil

parameter. A recently introduced piece of equipment, the

Marchetti flat plate dilatometer, however, has the poten-

tial for determining a wide variety of geotechnical

parameters. It has been widely used in Italy and has

proved very successful and accurate in obtaining various

strength, insitu stress and compressibility properties.

The University of Florida Geotechnical group possesses

the first Marchetti dilatometer in the United States.


1.2 Purpose

The primary purpose of this research is to develop

a better understanding of the Marchetti dilatometer

especially with regard to the test drainage conditions

and the experimentally derived correlations.





3

1.3 Scope

In order to evaluate the drainage conditions around

the Marchetti dilatometer, a new insitu testing probe,

identical in shape but measuring only pore pressures,

was developed. Associated calibration and de-airing

devices were also designed and built.

A program of field testing at five sites near the

University of Florida campus was carried out. Dilatom-

eter the new pieoohblade and cone Tpenetration test

soundings were made and disturbed and undisturbed samples

collected for laboratory testing.

Based on the test results conclusions are drawn

regarding the dilatometer drainage conditions and the

validity of the Marchetti correlations in the tested

Florida soils.












CHAPTER 2

DESIGN OF PIEZOBLADE


2.1 Introduction

The piezoblade consists of a stainless steel body,

the same shape and dimensions as the Marchetti dilato-

meter, but wi hi a flush mouined pure presturLe Ltranducer-

in place of the expanding membrane. It is penetrated

vertically into the ground at a slow constant rate using

the University of Florida cone penetration test truck.

The device can be used to record both the pore water

pressures generated during insertion and the dissipation

of excess pore pressures if penetration is ceased.

During penetration, the magnitude and sign of the recorded

pore pressures indicate both the soil type and the density

or overconsolidation ratio state.

An advantage of the piezoblade is that its thin

(14 mm) plate shape disturbs the soil less than the

standard, 36 mm diameter, piezocones. This has been

demonstrated in an experimental laboratory study described

in -detail in Chapter 6.

The purpose of building the piezoblade was not

simply to develop a better, less disturbing, piezometric

probe, but rather to have an instrument which would permit

a better understanding of the Marchetti dilatometer.
4





5

Since the dilatometer itself does not measure pore pres-

sures, it is not possible to know, except in the extreme

and obvious cases, whether a test is being performed in

a drained, undrained or partially drained manner. By

performing piezoblade and dilatometer tests adjacently

in the field, it will be possible to relate dilatometer

parameters and drainage conditions.


2.2 The Blade

The body of the piezoblade is identical to that of

the dilatometer, Figure 2-1. It was machined from a

single piece of stainless steel. The male threads are

three millimeters deep and three millimeters apart, and

require a short adaptor to connect to the standard cone

penetration test outer rods. The cavity for the pore

pressure transducer and porous stone assembly, and the

groove for the wiring and thermal compensation section,

were machined into the blade. The original dilatometer

shape was chosen by Dr. Marchetti. The width of 90 mm

was chosen so that the dilatometer could, if necessary,

be penetrated through standard 100 mm and 4 inch ID casing.

The thickness of the blade, 14 mm, was chosen as small as

possible consistent with the requirement that it not be


easily damaged or bent.













T
20.0


48.0
1


R=186.0


180.0


T
50.0


Figure 2-1. Sketch Showing Piezoblade Dimensions







2.3 The Transducer and Connector

The transducer is the main component of the piezo-

blade. It must have a high sensitivity in order to

measure small changes in pressure and be as robust and well

protected as possible. The transducer chosen was a model

number EPN-0350-100 with a range of 0 to 100 psi and an

overrange of 200 psi. The recommended excitation is 15

volts and the operating temperature range is -600F to

+250 F. Figure 2-2 shows detailed dimensions of the trans-

ducer. The cable which connects the piezoblade to the

surface control and recording instruments is 100 feet long.

The voltage drop in the wire through the cable was measured

and found to be 0.05 volts. Thus, to supply 15 volts to the

transducer, the input voltage at the surface must be 15.05

volts. Output signals were measured at the transducer

and after passing through the 100 foot wire. No change in

signal was found at any level.

Front and side view sketches of the piezoblade with

important dimensions are included in Figures 2-3 and 2-4.

Figure 2-5 shows in detail the location of the transducer

in the piezoblade. The transducer is permanently held in

place by the holder shown below the transducer in Figure 2-5

and in detail in Figure 2-6. The holder is cemented in

place using a special glue described later, and is removed

only if the transducer is damaged and to be replaced.

Figure 2-7 is a photograph of the piezoblade showing the

transducer cavity and groove. In Figure 2-8 the transducer









---7.60-


T
2.55

5
5.10


I---- 15.20


mm
mm


,ctual size of pressure


Thermal compensation
section


Figure 2-2. Dimensions of the EPN-0350-100 Pressure
Transducer

















Location of
connector


Porous stone
holder -


Porous


Slot for thermal
compensation section




Transducer
.Transducer holder
5
mm


Figure 2-3. Side View of the Piezoblade Probe



































22.0




35.0


12.0
i_


Figure 2-4. Front View of Piezoblade Probe


90.0









k-- ro


r-iE
IE


-T-


Oc\J
koa\


kbo


LC
-,--


rl c~
Ln--C,-l













K A\\\\~\\\~\\\


19.2 1


1
mrii


Figure 2-6. Piezoblade Transducer Holder


-f1
1.9
_a







































Figure 2-7. Piezoblade Showing the Transducer Cavity
and Wiring Groove


Figure 2-8. The Transducer in Place in the Piezoblade


I Ir


_ _ _i __ _i r





14

is in place just prior to affixing the holder.

Located above the transducer in Figure 2-5 are the

porous stone and its holder. The holder, shown in detail

in Figure 2-9, consists of a stainless steel ring with

counter-sunk screws by which it is attached to the blade.

It holds the very fine porous stone in place. Photographs

in Figures 2-10 and 2-11 illustrate this part of the

piezoblade.

With the transducer in place, the wires lie in the

groove and are threaded through the 5.8 mm hole to the

head of the blade (see Figures 2-3 and 2-4). At this

location a watertight connection is required between these

wires and the 100 foot cable. A search of electrical

supply companies failed to produce a connector of the

desired size. The junction described below was therefore

designed and has performed satisfactorily. Within the

threaded head of the piezoblade, shown hatched in Figure

2-12, the plastic disc A with four pins protruding through

each face is seated on an 0-ring and held down by tighten-

ing the threaded ring B. Parts A and B are shown in detail

in Figure 2-13. Ring B is screwed using the special tool

shown in the photograph of Figure 2-14. The four wires

from the transducer and the four from the cable, Figure

2-15, are soldered to the lower and upper pins respectively

of the disc A before it is inserted. The end of the cable

has a swagelok 1/4 inch male end which screws into the top

of the piezoblade head making a watertight connection.





15

-16 .---
-6.0 -- 14.0 -- 2. 0

T 8.0



S3-- 8.0-
t-------58s.0 ---------\







Center of screws
is on a 28 mm
circle



/ \


//













5
mni


Figure 2-9. Piezoblade Porous Stone Holder



























Figure 2-10.


Front of the Piezoblade with the Porous
Stone and its Holder


Detail of Porous Stone Holder


Figure 2-11.























40.0


- 21.0--I


35.0


Figure 2-12.


The Piezoblade Connector in Place with the
Transducer and Cable Wires Attached






Centers of pins
are on a 3 mm
diameter circle


T
3.0
L


-A k-.8
- l 0


L 9.0


T
5.0



5.0



5.0

i


7-
2.0
+
3.0
I


ameter=.8 mm


Figure 2-13. The Piezoblade Electrical Connector


h-3.0-1


1-- 5.4--1



























Figure 2-14. Special Tool to Screw the Connector in Place


Figure 2-15. The Piezoblade Cable





20

With the transducer, the thermal section and the connector

all in place, the transducer holder is attached. It is

held temporarily in place by the de-airing unit holder,

Figure 2-16. The center screw impinges on the indentation

on the back of the transducer holder, Figure 2-6. The

groove and the surroundings of the transducer holder are

then covered with a special glue. This was made by

mixing a few drops of Schnellklebstoff FFX60 with about

a 1/4 teaspoon of the powder Schnellklebstoff FFX60

Komponete A. This produced a strong glue which, after

a year of testing, remains intact.


2.4 The Cable

A 100 foot length of cable connects the piezoblade

to the ground surface instrumentation. The cable,

consisting of four conducting wires which transmit to and

from the transducer, is enclosed in 9/32" ID, 3/8" OD

plastic tubing. The cable was threaded through the

tubing using the following procedure. The tubing was

laid in a straight line and a 14.7 psi vacuum applied at

one end. A cork with a thin thread attached was introduced

at the other end and drawn through the tubing by the

vacuum. A stronger thread was then attached to the fine

thread and pulled through. Finally the cable was tied

to the strong thread and it was pulled through. The

plastic tubing with a swagelok connector screws into the

top of the piezoblade. To prevent the cable from ever










































rr




S rr


Figure 2-16.


The De-airing Unit Holder


Figure 2-17. The Test Control and Recording Units


- qlm


r

a
c
Li; I,


. I





22

being accidentally pulled back up into the tubing, a simple

twisted wire collar of large diameter was placed on the

cable. In addition, the wires which connect the cable

to the connector, Figure 2-12, are very thin and will

break easily if any severe pulling on the cable should

occur. These can be easily replaced.


2.5 Control and Recording Units

During the performance of a test, four electrical

control/recording units are employed. These are shown

hooked together ready for testing in the photograph of

Figure 2-17. Because the piezoblade cable must be

threaded through the string of drill rods it is not

possible to have permanent electrical connectors or clips

on the four wires. Instead, these exposed wires are

attached to four alligator clamps in the Clamp Box,

Figure 2-18. This then connects to the Control Box via

banana jacks. The Control Box circuitry is shown in

Figure 2-19. It has eight female banana jacks. Four

connect via the Clamp Box to the transducer, two connect

to a voltmeter and two to the recorder. A three position

switch allows output of the excitation voltage or the

signal voltage. The center switch position is off. Two

9-volt batteries provide the power while a rotary resistor

switch, Figure 2-20, permits exact control of the excita-

tion voltage.

The voltmeter used in the research was a B and K-

Precision Model 2845 Autoranging Digital Multimeter
























p. '.


Figure 2-18. The Clamp Box




















to
signal signal
recorder












oa

S I

to
W voltmet




10C




O female banana jack
Figure 2-19. The Control Box Circuitry














y


Figure 2-20. The Test Control Box


Figure 2-21. The Voltmeter







manufactured by Dynascan Corporation, Figure 2-21. This

model is a high-accuracy instrument for measuring dc and

ac voltage, dc and ac current, and resistance. Among

the performance features are 0.1% accuracy, extensive

overload protection and long battery life. Since the

piezoblade penetrates the soil at a constant rate, a chart

recorder was used to provide a permanent record of the

pore pressure changes. The recorder used was manufactured

by Linear Instrument Corporation, their model number 142.

Figure 2-22. It is a multirange potentiometric, null

balance servo recorder which can be powered either by mains

electricity or by rechargeable batteries. The unit is

small, weighs only 5 kilograms and is convenient for

field testing. The chart width is 100 mm.


2.6 Calibration of the Pore Pressure Transducer

Before sealing the transducer permanently into the

probe, it was necessary to calibrate it, i.e., experimen-

tally establish the relationship between applied pressure

in psi and the output signal in volts. To do this the

special calibration unit shown in Figures 2-23 and 2-24

was built.

The device consists of a metal ring through which

two holes were drilled and threaded. To the upper hole

of Figure 2-23 was threaded plastic tubing connected to

an accurate pressure regulator and gauge and to a gas

source. Through the lower threaded hole was a screw by
































Figure 2-22. The Linear Instrument Corporation Recorder







-83.3
--- 48.6 -
--- 35.9 --
-I 8.0\--


0


Section A-A
without holder and transducer


H--24 .- 0
K-l 6. 0-


8.0
8.0
4_


3.0
1_
T


4.0
7_
-T


10
mm


Figure 2-23. The Calibration Unit


T
20.0
1


' I

































Figure 2-24. Photograph of the Calibration Unit





30

which the pressure transducer and its holder were tightened

against an 0-ring, forming the pressure cavity. Known

increments of gas pressure were applied and the transducer

output recorded. The excitation voltages were also

varied during the test, between 14.3 and 16,1 volts in

0.1 volt increments. Figure 2-25 shows the final calibra-

tion curves. The calibrations were all linear over the

pressure range tested, with a slope for the 15 volt

excitation giving a relationship of 3.54 mv/psi. The

effect of varying the excitation voltage on the output

voltage was to increase it by 1 to 2 my for each 0.1 volt

increase in input voltage. In a particular output signal

the effect of a 0.1 volt change in excitation voltage is

thus a 0.28 to 0.56 psi change in pressure. These curves

can be used to interpolate the results of a test if the

input voltage is not exactly 15.0.


2.7 De-airing the Piezoprobe

A very critical part of any laboratory or field

testing method which attempts to measure pore water

pressure is the de-airing of the unit. Test results

cannot be relied upon with confidence if there has been

failure to remove all gas bubbles from the system, or if a

fluid has been used from which gas may come out of solution

during testing, Baligh et al. (1980).

In this research, a special piezoblade de-airing unit

was constructed. It consists of four parts, the holder

Figure 2-26, the cylinder Figure 2-27, the top cap section







-31


/ ---15.9 volts
--- -15.6 volts

-- -15.3 volts

S --- 15.0 volts

--- 14.7 volts
-----. 14.4 volts


10 20 30 40 50 60
Pore Pressure PSI


Figure 2-25. Calibration Curves for Different Excitation
Voltages


200




18C


U)
I--,
caI
014
.r-
c-I
Sr
















/ "--- 16.0 volts
-- 15.7 volts
15.4 volts
-- 15.1 volts
--- 14.8 volts
"--- 14.5 volts


10 20 30 40 50
Pore Pressure PSI


Figure 2-25.


220


200




180




^160

0
o
>
*-,-
" 140




1. 120
C)


(continued)













220




200




180




c 60




E
r-


h9
o2
*140




1 20
co)


10 20 30 40 50 60
Pore Pressure PSI


Figure 2-25. (Continued)


."-- 16.1 volts
S---- 15.8 volts
-'-- 15.5 volts

"---- 15.2 volts
--- 14.9 volts
-- 14.6 volts
--- 14.3 volts








0 0 0 20.0
_L


-H 1-5.0


110.0


j--18.0 -


72.0


k-17.5-


-----55.5---


-15. o-


Figure 2-26. The De-airing Unit Holder

























--- 84.0

--49.0---


45.0


Figure 2-27. The De-airing Unit Cylinder


T
20.0
1_

f-
15.0
-L







Figure 2-28, and the inside screen Figure 2-29. The

assembled unit is shown in Figure 2-30. The thick-walled,

stainless steel cylinder with 0-rings top and bottom is

placed on the piezoblade and tightened down by means of

the two outer screws on the holder. The center screw is

used only during the cementing in place of the transducer

holder, described in Section 2.3. The porous stone and

its holder are placed in the cylinder and the screen put

in place. About a one centimeter depth of de-aired water

is added and the top cap screwed on.

The unit is then turned upside-down, such that the

water is now sitting on the lucite top and the porous

stone and holder are on the screen. A vacuum is applied

via the cylinder's quick connect and all air removed from

the space above the water, from the piezoblade cavity and

from the porous stone. The unit is then turned the right

way up and the water allowed to flood the piezoblade

cavity. The vacuum is disconnected and air allowed in on

top of the water. The top cap can then be unscrewed and

the screen removed. The porous stone and holder are

assembled and screwed in place, underwater.

The piezoblade and the de-airing assembly are then

placed in a bucket of de-aired water and the de-airing

unit unscrewed. Finally the de-aired and saturated

piezoblade is placed in a plastic bag full of water and

sealed. It is ready for field testing. Figures 2-31 and

2-32 show photographs of the de-airing unit.














T
15.0









-- 70.0-

----50.0



10.0


25.4




5
'mm


Figure 2-28. The De-airing Unit Top Section







































T
14.5

29.0







mm


Figure 2-29. The De-airing Unit Screen


U


rFT-FT-FT-F-F-T-


















































mm

Figure 2-30. The Assembled De-airing Unit













I ~I
r- aancne tt-S


.5JU


Figure 2-31. Photographs of the De-airing Unit's Cylinder,
Top and Screen


_








































































Figure 2-32.


Photographs of the De-airing Unit and the
Piezoblade


I -----7~Y-YIII--- I---
c












CHAPTER 3

OTHER INSITU TEST DEVICES


3.1 Introduction

In the field testing program associated with this

research a large number of dilatometer and cone penetra-

tion tests were performed adjacent to the piezoblade

soundings. This chapter very briefly describes these

devices, the test procedures and the relevant data reduc-

tion methods.


3.2 The Dilatometer Test

The flat plate dilatometer was developed in Italy

by Dr. Silvano Marchetti, professor of soil mechanics

at L'Aquila University, Marchetti (1975, 1980). The

device was originally designed to measure the insitu soil

modulus for laterally loaded piles. However, extensive

field testing has generated a number of correlations which

now permit the evaluation of many other geotechnical param-

eters.


3.2.1 The Equipment

The equipment consists of three major components, the

blade, the control unit, and the connecting cable. Figure

3-1 is a photograph of all the test equipment and includes,

42












L


Figure 3-1. The Dilatometer Test Equipment


Figure 3-2. The Flat-blade Dilatometer


It r




44

besides the three basic units, some calibration equipment

and a box of tools. The blade is shown above in Figure

3-2. It is a stainless steel plate with a sharpened

bottom edge and is threaded for connection to a string of

drill rods. On one face of the blade is a thin circular

expandable, steel membrane. The test consists of pushing

the plate vertically into the ground and stopping at

frequent intervals to determine the gas pressure behind

the membrane needed to expand it 1 mm into the soil. The

cable which connects the dilatometer to the control unit

is threaded through the drill rods and is a combined gas

and electrical line. The control unit, Figure 3-3,

consists of a pressure gauge and regulator by which gas

pressure is sent to the dilatometer, and a galvanometer

and buzzer which indicate when the desired displacement

has been achieved.


3.2.2 Dilatometer Test Procedure

Prior to testing, a brief calibration is required.

The syringe and pressure/vacuum gauge of Figure 3-4 are

attached to the pressure control unit instead of the

normal gas source. A vacuum, applied by drawing the

syringe plunger, pulls the dilatometer membrane into con-

tact with its seating, completing an electric current and

activating the buzzer. This vacuum pressure, AA, is

recorded. A pressure is then applied by pushing in the

plunger and the pressure AB noted when the buzzer is



























Figure 3-3. The Control Unit


Figure 3-4. The Calibration Equipment





46

reactivated indicating a membrane expansion of 1 mm.

These procedures are repeated until consistent values are

obtained.

For the field test, the dilatometer is pushed into

the ground at a slow constant rate by the University of

Florida cone penetration test truck. At 20 cm depth

intervals, penetration is ceased and a test performed.

During insertion the soil pressure on the membrane presses

it onto its seating and the buzzer sounds. To run the

test, the gas pressure behind the membrane is slowly

increased by means of the central panel regulator. When

the membrane separates from its seating the buzzer

deactivates, and the pressure acting, A, is recorded.

When the buzzer reactivates, the 1 mm expansion has been

achieved. This pressure, B, is also recorded and the

equipment immediately vented so as not to overstress the

metal membrane. The dilatometer is then ready to be

penetrated to the next test depth.


3.2.3 Dilatometer Data Reduction

The dilatometer parameters ID, KD, and ED are calcu-

lated by means of the following equations, Marchetti

(1980),

PO = 1.05(A-ZM+AA)-0.05(B-ZM-AB) (3-1)

P1 = B-ZM-AB (3-2)

AP = P -Po (3-3)







D = (P1-P)/(P0-U0 (3-4)

KD = (P0-U0)/v (3-5)

ED = 38(P1-P0) (3-6)

where

ID = Material index

KD = Horizontal stress index

ED = Dilatometer modulus

PO = Corrected first reading. Pressure to separate

the membrane from its seating

P1 = Corrected second reading. Pressure to expand

the membrane center one millimeter into the soil.

U0 = Hydrostatic pore water pressure

A = First dilatometer reading

B = Second dilatometer reading

AA = Free-air correction for A

AB = Free-air correction for B

ZM = Zero pressure gauge reading when control unit is

vented

j = Vertical effective stress at depth of membrane

center

P0 and P the corrected values of A and B, depend

on the calibration pressures and on the geometry of the

measuring device. The equations are derived in Marchetti's

(1980) paper.

The Material Index ID correlates well with particle

size, (ID<0.6 = clay, 0.61.8 = sand),
Figure 3-5.





48



The Horizontal Stress Index KD is of the form of a

lateral stress ratio, i.e., the ratio of an effective

lateral pressure to the vertical effective stress.

The Dilatometer Modulus ED was developed from a

theory of elasticity solution to the following problem:

a load on the surface of a half-space with no normal

displacement of the surface permitted outside the loading.

2D P (1-v-)
IT E (3-7)

where

E = Young's modulus

v = Poisson's ratio

D = Membrane diameter = 60 mm

S = Movement of membrane = 1 mm

2(60) P (1-v2
therefore, 1 = 2(6) P

DE
ED = E2 = 38AP (3-8)
1-v

Experimental correlation with the dilatometer param-

et ers defined above allows the evaluation of several

geotechnical parameters, including KO, OCR, M(=1/mv),

C and 0. Details of all the correlations are given in

the Marchetti (1980) paper. Those for the overconsolida-

tion ratio (OCR) and the constrained modulus (M), which

are used in Chapter 7 of this thesis, are listed below.










CHART FOR SOIL DESCRIPTION AND y EVALUATION ['/j= t/n3


0.1 0.2 0.5 1 2 5
MATERIAL InDEX ID
Figure 3-5. Dilatometer Soil and Density Evaluation Chart
(Marchetti and Crapps, 1981)







If ID<1.2


If ID>2.0

If 1.2 D


OCR = (.5KD)1.56


OCR = (.'65KD) 191

OCR = (mKD)n


P = (ID-1.2)/0.8


m = 0.5 + 0.17P

4 L'f I n c
11 j.I _I* j


(3-12)


(3-13)


\j-,:vL:


If the value of OCR predicted from the dilatometer

test is less than 0.8, it is written as OCR<0.8, because

it is not within the range of valid correlation.


M=RM E D


(3-15)


where


If ID<0.6

If I D3.0

If 0.6

RM = 0.14 + 2.36 log KD


RM = 0.5 + 2.0 log KD


R = Rmo+ (2.5 R )log K
m,o m,o D

Rm, = 0.14 + 0.15(ID-0.6)
.m,o


If the calculated value of RM is less than 0.85, then

0.85 is used in the determination of M.


where


(3-9)

(3-10)

(3-11)


(3-16)


(3-17)

(3-18)


(3-19)





51

3.3 The Cone Penetration Test

The cone penetration test or Dutch cone test originated

in Holland and consists of pushing a solid tip penetrometer

into the ground at a constant rate. Surface measurements

of the pressure required for penetration are made.

Theoretical analyses and experimental correlations permit

an evaluation of soil type and many geotechnical param-
eters.


3.3.1 The EquipmentL and TesL Procedure

In this research a Begemann friction tip was used,

Figure 3-6. This 600, 10 cm2, mechanical tip requires

the use of an outer and inner loading rod system. When a

load is applied to the outer rod, the tip, in its collapsed

state, Figure 3-6(a), is penetrated to the desired test

depth. A load is then applied to the inner rod, which

first penetrates only the point, Figure 3-6(b). The

measured pressure permits the calculation of qc, the cone
2
end bearing. Further penetration causes the 150 cm

friction sleeve to be engaged and both the point and the

sleeve move, Figure 3-6(c). From this pressure is calcu-

lated q + fs, where fs is the unit side friction.

Finally, the tip is again collapsed and penetrated to the

next test depth by transferring the load to the outer rods.

The University of Florida cone truck was used to

penetrate the Begemann tip. The truck, which weighs more

than 13 tons, provides the necessary reaction while the































_ I


Figure 3-6. Begemann Tips







tip-is penetrated by means of a hydraulic ram. Pressures

are read from two Bourdon gauges, a low range 0 100 kg/cm2

and a high range 0 600 kg/cm2

Depths and gauge pressures are usually punched into

a programable hand calculator or main line computer and

the data automatically reduced to give qc fs and FR, the

friction ratio. Plots of q and FR versus depth are

available from the computer, see for example Appendix C.


3.3.2 Cone Penietration Test Correlati-ons

A large number of primarily experimental correlations

are available for determining geotechnical parameters and

for foundation design. Schmertmann (1977a) contains

detailed descriptions of many such correlations, including

evaluation of soil type (Figure 3-7 and Table 3-1) relative

density, sensitivity, OCR, C 0', and design procedures

for piles, settlement of footing on sand, consolidation

settlement of clays and compaction control.




















1000
8

6


FRICTION RATIO, (SLEEVE FRICTION/CONE BEARING),%
Figure 3-7. Cone Penetration Test Soil Evaluation Chart
(Schmertmann, 1977b)


NOTES:
L Expect Some Overlap in the Type of
Zones Noted Below. Local Correla-
aions ore Preferable.
2. Developed from Work of Beqemann
%(965" n Bosa: n Candi;, Sd 0i
North Centrol Floridc.

C,,
o Dense or SILT-SAND /
Cemented MIXTURES
~ a- ----
SCLAYEY-SANDS
Q AND SILTS
z SANDY AND SILTY
SSAND CLAYS

S___ __ __ INSENSITIVE
~ NON-FISSURED-
t/ IN O R G A N IC
CLAY


Loose
Slilf


- I -s [ '-
Medium ^
/ ORGANIC
[--7 CLAYS '.IiXED-

Soft /
Friction Ratio Values Decrease in SOL
Accuracy with Low Values atof qc and I
When Nithin a Few Feel of the Surface Very Soft
I I_____________________ ___


100
8

6

4



2



10
8

6

4











Table 3-1. Values of fs/q for Loose Medium and
Dense Sands (SShmertmann, 1977b)




Sand Loose Medium Dense
(Dr) 30% 60% 90%

K 1 2 4

tan 6
(Steel) 1/3 1/3 1/3

c
20 80 220
(bar)
f
s 1/3 2/3 4/3
(bar)


fs /q 1/60 1/120 2/330


K = Passive stress ratio
P
fs/q = FR = Friction ratio












CHAPTER 4

FIELD TESTING


4.1 Introduction

The purpose of the field testing was to test the

newly developed piezoblade and to establish relationships

betwcn it and the dilatometer. Of prLima 11y IIporuitance was

an evaluation of the drainage conditions around the dilatom-

eter in different soils. This was determined by using the

identically shaped piezoblade adjacent to dilatometer

soundings and analyzing the test results. Five sites close

to the University of Florida campus were chosen and dilatom-

eter, piezoblade, cone penetration tests and sampling

performed. This chapter describes the sites, locates and

numbers all the tests performed at each site and briefly

describes some of the testing procedures.


4.2 Test Sites


4.2.1 Location

Five test sites were chosen in Alachua County, Florida,

within short driving distances of the University of Florida

campus. Four of the sites bounded Lake Alice which is

located on the edge of the University campus. The fifth

site was at Lake Wauberg which is owned by the University

for recreational purposes and is located about 12 miles

56




57

south of the campus. The sites were chosen near the two

lakes as it was desirable to have high groundwater levels.

For the piezoblade tests, in order to maintain a fully

saturated measuring device,it is necessary to initially

drill to below the water table before inserting the probe

into the hole. It was desirable that this be done by

hand augering. At the sites chosen, the depth to the

water table varied between 50 and 200 cm, and with dis-

tances from the water's edge.

Figure 4-1 shows the location of Alachua County

within the state of Florida, and also the city of Gaines-

ville, in which the University of Florida is situated.

Figure 4-2 is a detail of a map and shows the locations

of Lake Alice and Lake Wauberg.


4.2.2 Site Geology

Alachua County lies in the north-central portion of

peninsular Florida in the coastal plane physiographic

province (Wiener, 1982). The entire county is underlain

by limestone of the Ocala Group of late Eocene age. A

thick sequence of Hawthorn Formation clays and sands

overlie the limestone in eastern Alachua County but are

intermittent or nonexistent in the central and western

portions of the county. A thin cover of loose surficial

sands overlies the Hawthorn Formation. In western Alachua

County a thick sequence of pleistocene dune sands overlies

the Ocala Formation. The Hawthorn Formation consists of

varying amounts of clay, quartz sand, and limestone with








FLORIDA


Figure 4-1. Location of Alachua County and the City of
Gainesville














































Figure 4-2. Location of Lake Alice and Lake Wauberg





60

phosphatic grains and pebbles. One of the most important

characteristics of the Hawthorn Formation is its horizon-

tal and vertical heterogeneity (Pirkle, 1956).

Lake Alice is located approximately in the center of

Alachua County. This area consists of a nearly flat plain

underlain by limestone of the Crystal River Formation and

mantled by thin sandy soil and residual outlines of the

Hawthorn Formation (Opper, 1981). Lake Alice is approxi-

mately 70 feet above sea level. Figure 4-3 shows a

topographic map of the vicinity of the lake.

Lake Wauberg is located near the southern border of

Alachua County and centrally in an East-West direction.

The area around the lake consists of three different

geological layers. The top layer is sand or a sand/clay

mixture. According to Carl Opper (1981) the sand layer

is from two to twelve feet thick with an average of about

four feet, while the sand/clay layer is from five to seven-

teen feet in thickness. The clays consist of montmorillo-

nite and kaolinite. Under this top layer is the Hawthorn

clay which is a very dense plastic and very impermeable

layer. The Hawthorn also contains many lenses of sand

and limestone.

Lying below the Hawthorn Formation on an unconformable

surface are several thousand feet of limestone and dolomite,

the Ocala limestone. Figure-4-4 shows a topographic map

of the Lake Wauberg area. Figure 4-5 shows a block

perspective diagram of an Ocala Limestone structure contour







































__



















































SCALE
2000
A I


Figure 4-4. Topographic Map of Lake Wauberg


0 2000 4000 FEET




















0
-P





r.
a,
0





c








U)
cD
0







H


0




co




4-3





aa,







0*
Hc




a,




bfl





64

map produced by a computer. This illustrates that the

elevation of the top of the rock is very variable and

changes rapidly.


4.2.3 Site Plans

Figures 4-6 to 4-10 contain plans of the five test

sites. For each site, symbols indicate the location and

type of test performed. Distances are in general marked

from the water's edge. The boring numbers are indicated

beside the symbols. These allow the profiles and test

results of future sections to be related back to their

field locations. For example, the following tests were

performed at Site 3, Figure 4-8; three piezoblade sound-

ings, numbers 4, 5, and 13; three dilatometer soundings,

numbers 4, 5, and 12; four cone penetration tests, numbers

3, 9, 10, and 11; two disturbed sampling borings, numbers

3 and 4; and one undisturbed sampling boring, number 2.

The piezoblade profiles can be found in Appendix A, the

dilatometer results in Appendix B, the cone penetration

test results in Appendix C, consolidation test plot from

undisturbed samples in Appendix D, triaxial test plots in

Appendix E and soil classifications from disturbed samples

in Chapter 5.

4.3 Piezoblade Testing

4.3.1 Test Preparation

The piezoblade, de-aired and saturated as described

in Section 2.7, was brought to the site enclosed in a water



















LAKE ALICE (Site 1)


2'1


9'1


S 5

20'





12

+8

-1 6'1 10

1A
gl


11'


e _- C ecrerrt r1~

G iBT-Cozst.tl. m3~s
-MT

o DS
+ CPT

& US


Site-1, North of Lake Alice


S2 3'
*2


Figure 4-6.











LAKE ALICE (Site 2)









15'


1.5'


*3
05
-+2


Figure 4-7. Site-2, East of Lake
Alice


t .5'
S.5'


253


PBT-Incremental

SPET-Contirucus

* DMT
O DS

4- CPT

A US



















C
1-

Z m
4 0

I I









E E-
K _____ -T I

Q ----
1 0





7
N N

l I




o------
^ ~-







'________


/


cl)
C-


)


j

















LAKE ALICE (Site 4)


12'


12


31 7

e 6


Figure 4-9. Site-4, North of Lake
Alice


P2T-Incremental

* DMT
+- r'PT


0

A


DS

US

















boat
ramp

9 Y

30'




30'















PBT-Incrementa
DMT
+ CPT
A US


Figure 4-10. Site-5, Northwe


N

LAKE WAUBURG (Site 5)


8

2
1.5'


9
A4


4--


7

21'


40'


of Lake Wauberg




70

filled plastic bag and submerged in a bucket of water.

The test hole was hand augered to about 30 cm below the

water table and the truck located over the hole. The

bucket and piezoblade were then placed adjacent to the

hole under the truck, and the 100 foot cable passed up

through the hole in the floor of the truck. The cable

was threaded through the appropriate number of 1 m drill

rods, and the four conducting wires connected to the Clamp

Box. The remaining control and recording instruments were

hooked up as described in Section 2.5, and the excitation

voltage set to 15 volts.

The piezoblade was then removed from the bucket,

screwed to the first length of drill rod and lowered

slowly into the test hole. Additional rods were added

until the probe was sitting underwater at the bottom of the

hole. It was then pushed about 10 cm into the soil,

withdrawn the 10 cm and this process repeated a number of

times to ensure that the plastic bag was torn and the blade

was in contact with the natural groundwater. The depth of

the piezoblade below the ground surface was accurately

measured and the test was then ready to proceed.


4.3.2 Types of Piezoblade Tests

Two different types of piezoblade tests were performed,

continuous penetration and incremental penetration. In the

continuous test the blade was pushed into the ground at a

constant rate of 2 cm/sec for the entire 1 m penetration





71

length of the rods. Only when an additional length of

rod needed to be added was the test penetration stopped.

A continuous plot of generated excess pore water pressure

versus' depth was thus obtained for each sounding. Since

the recorder speed was constant, linear interpolation on

the chart over each meter length of depth was possible.

Millivolt readings at 5 cm ground depth increments were

taken and using the correlations of Figure 2-25, pore

pressures determined and plotted. In Table 4-1 the

continuous penetration tests are indicated along with the

page numbers where test plots can be found.

In the incremental test, a penetration rate of 2

cm/sec was again used but insertion was stopped every 20 cm

and the excess pore water pressures allowed to dissipate

for up to two minutes. This was done to simulate the

dilatometer test, in which tests are performed at 20 cm

increments and take about one minute each to perform.

Table 4-1 also lists these tests and where the plots may

be found.


4.4 Dilatometer Testing

After calibrating the dilatometer as described in

Section 3.2.2, the cable was stretched out in a straight

line and the desired number of drill rods run onto it.

The cable quick connect was then inserted into the control

unit. The pressure source was also connected to the control

unit and set to a pressure less than the maximum capacity of









Table 4-1. List of Piezoblade Tests Performed


Test Site Test Depth Date Test Results
No. No. Type (m) Tested On Page
*

1 1 CP 5.00 07/01/81 192
2 1 CP 9.00 07/06/81 193

3 2 CP 8.00 07/09/81 194
4 3 CP 7.10 07/17/81 195

5 3 CP 9.00 07/21/81 196
6 2 IP 3.20 08/01/81 203

7 4 IP 2.00 08/03/81 204
8 5 IP 4.80 08/14/81 205

9 5 IP 6.20 08/15/81 206
11 1 IP 5.20 08/17/81 207
12 1 CP 8.00 09/22/81 201

13 3 IP 3.50 09/24/81 208

*CP=Continuous Penetration
IP=Incremental Penetration





73

the unit. Originally carbon dioxide was used but some

freezing of the regulators was found, so a change was

made to nitrogen gas. The zero pressure ZM, the reading

on the control unit gauge at zero pressure, was recorded.

The first lengths of drill rod were attached and the

dilatometer hung from the hydraulic ram just above the

ground surface. The ground wire, which completes the

electrical circuit, was connected to the control box and

by an alligator clip to the drill rods. The blade was

then penetrated into the ground at a constant rate of

2 cm/sec in 20 cm increments and testing performed as

described in Section 3.2.2. The micrometer valve which

controls the gas passing to the dilatometer was opened

slowly, ideally taking 15 seconds to read pressure A,

membrane lift-off, and a further 15 seconds to reach

pressure B, the 1 mm membrane expansion. On reaching

pressure B, the vent valve was immediately opened and

finally the micrometer valve closed. The dilatometer was

then ready for penetration to the next test depth. A

computer program was used to reduce and plot the field

data. Table 4-2 lists the dilatometer tests performed

and the pages on which the results can be found.


4.5 Cone Penetration Testing

Cone penetration tests, with which the University of

Florida Geotechnical group has considerable experience,

were performed at all sites. The test equipment has









Table 4-2. List of Dilatometer Tests Performed


Test Site Depth Date Test Results
No. No. (m) Tested On Page


5.00

8.60

7.00

7.40

8.80

1.60

4.80

5.80

4.60

7.80

7.80


07/01/81

07/06/81

07/09/81

07/20/81

07/20/81

08/03/81

08/14/81

08/15/81

08/15/81

10/23/81

10/24/81


210-221

211-222

212-223

213-224

214-225

215-226

216-227

217-228

218-229

219-230

220-231






75

already been briefly described in Section 3.3.1. In the

mechanical system employed during this research, inner

and outer rods are used to transmit the loads to the tip.

Inner rods which had been removed for piezoblade and

dilatometer testing were lubricated and replaced within

the outer rods. A friction reducer was used on the first

rod above the tip. Tests were all performed in the standard

manner, with a 2 cm/sec penetration rate and readings taken
cv-ry 20 cm. Table '-3 licf the cone -enetra+inn +cs+

performed and the location in this dissertation of the

test results.









Table 4-3.


List of Cone Penetration Test Soundings
Performed


Test Site Depth Date Test Results
No. No. (m) Tested On Page

1 1 9.80 07/07/81 233
2 2 7.40 07/07/81 234

3 3 8.40 07/21/81 235
4 5 5.80 08/15/81 236

5 5 6.00 08/15/81 237
6 1 8.80 09/23/81 238

7 1 8.80 09/23/81 239
8 1 8.80 09/23/81 240

9 3 7.00 09/24/81 241
10 3 7.80 09/25/81 242

11 3 8.60 09/24/81 243
12 4 1.60 06/16/82 244














CHAPTER 5

LABORATORY SOIL TESTS



5.1 Introduction

Samples were obtained from the five field test sites

for laboratory testing. Twenty-five disturbed samples

were collected from five hand augered borings to a maximum

depth of 3 m. Nine undisturbed piston samples, the

deepest to 6.1 m, were taken from five other borings.

Only classification tests were performed on the

disturbed samples. These included determination of

moisture content, specific gravity, Atterberg liquid and

plastic limits and grain size distributions. Consolidation

and triaxial tests were performed on the undisturbed samples

as well as the above classification tests.

The primary purpose of this testing program was to

provide a comparison between laboratory determined and

dilatometer determined soil parameters.


5.2 Sampling Procedures

The disturbed samples were obtained using the 5.72 cm

diameter, 20 cm long bucket hand auger shown in Figure 5.1.

This sampler, which was designed for use with the Menard

pressuremeter, can be used to depths of about 5 m

under ideal conditions. The rods are conically threaded

77





78

and come in one meter lengths. In this testing program

samples at 50 cm intervals were collected, placed in glass

jars and sealed.

The undisturbed samples were obtained using the

Swedish Fixed Piston Sampler shown in Figure 5.2. This

sampler is pushed into the ground using the cone penetra-

tion test truck. At the desired sampling depth, a steel

tape is passed down the string of drill rods to engage

a bayonet connection. This tape, whinh is fixed to the

truck, holds the piston while the sampler is further

penetrated. At the end of the stroke the tape is auto-

matically disengaged. The sampler is then withdrawn and

the sample in four, 17 cm long, 50 mm I.D., 53 mm 0.D.

fiberglass liners extruded. The liners are capped for

transportation to the laboratory. Table 5-1 locates the

nine piston samples taken, by boring number, site, and

depth.


5.3 Tests on Disturbed Samples

The tests performed on the disturbed samples were

all of the classification variety. Water contents were

determined for all samples immediately on return to the

laboratory. Specific gravity tests were also performed

on all samples while Atterberg liquid and plastic limits

were determined for those samples exhibiting cohesion.

Before sieving, each sample was washed through a #200

sieve to separate sandy material from the fines. Both





























Figure 5-1. The Hand Auger Sampler


I *


Figure 5-2. The Swedish Fixed Piston Sampler


~ii~i~:%r4n+~3'prpZsr ~








Table 5-1. List of Undisturbed Samples Taken


Number Site Sample Sample Date
No. No. Depth Obtained
(m)

1 1 1 1.50 2.17 08/10/81
2 3.45 4.12 08/10/81
3 4.50 5.18 08/12/81
2 3 4 4.40 4.80 09/24/81
5 5.50 6.00 09/25/81
3 2 6 3.45 4.20 09/28/81
7 5.40 6.10 06/16/82
4 5 8 3.40 4.10 07/15/82

5 5 9 3.40 4.10 07/15/82





81

fractions were then oven-dried and a sieve analysis later

performed on the coarse fraction. For any sample having

more than 10% by weight passing the #200 sieve, a hydrometer

analysis was also performed. Each soil was then classified

according to the Unified Soil Classification System.

All laboratory tests were carried out according to the

acceptable standard procedures described in Lambe (1951)

and Bowles (1970).

Results from the disturbed sample tests and their

classification are summarized in Tables 5-2 through 5-6.


5.4 Tests on Undisturbed Samples

One dimensional consolidation and consolidated

undrained triaxial tests were performed on the undisturbed

samples as well as the routine classification tests

described above. A total of fifteen consolidation tests

and nine triaxial tests were performed.


5.4.1 Consolidation Tests

The consolidation tests were carried out in two

different pieces of equipment, the Anteus and the Soil

Test consolidometers. Standard test procedures were

followed in all tests and are not described herein. The

Anteus equipment, shown in Figure 5-3, permits back

saturation of the sample. Drainage was from the top

surface only and load increments of 0.5, 1.0, 2.0, 4.0,

8.0, and 16.0 tons/ft.2 were used. The ring had a diameter

of 50.3 mm and the sample height was 19.0 mm.




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