Thesis_Jun7_2012

AXIAL COMPRESSION LOAD TRANSFER MECHANISMS
OF DRILLED SHAFTS IN WEAK POROUS LIMESTONE
Presentation of thesis in partial fulfill of the requirements for the degree of
Master of Science in Civil Engineering
José Roberto Ramírez Hernández
University of Puerto Rico at Mayaguez
Advisor: Dr. Miguel A. Pando López
Mayagüez, Puerto Rico – Thursday June 7, 2012

Index• Goals and specific aims
• Introduction
• Site Characterization
• Field test program
• Load test results
• Conclusions
• Acknowledgments
2

Goals and specific aims
Provide a basis for a load transfer criterion and evaluate experimentally the
characteristics of the ultimate unit side resistance of drilled shafts in weak
porous rock of Puerto Rico
• Design an experimental study of load test of drilled shafts based on high
precision instrumentation
• Analyze data from the field tests and compare the prediction based on
empirical relationships
• Classify and establish a geotechnical and geological characterization of the
limestone rock from La Montaña farm in Aguadilla, PR
3

Compressive axial bearing capacity
Mayagüez, Puerto Rico – Thursday June 7, 2012 4

Compressive axial bearing capacity
Idealized load-displacement behavior (after Carter & Kulhawy, 1988)

Drilled shaft axial capacity
Load transfer mechanism for socketed shaft (adapted from Zhang, 1998)

Unit side shear resistance
Factors affecting the τmax for drilled shafts in rock
Factors related to the construction Technique
• Interface roughness
• Length of time borehole remains open prior to concreting
• Destroyed or intact base resistance
Factors related to drilled shaft geometry
• Length
• Diameter
Factors related to the load test method
• Rate of load applied

Interface roughness
Wall roughness classification from Pells et al. (1980)
Roughness
Classification
Description
R1 Straight, smooth-side shaft, grooves or indentation less than 1.00 mm deep
R2 Grooves of depth 1-4 mm, width greater than 2 mm, at spacing 50 to 200 mm.
R3 Grooves of depth 4-10 mm, width > 5 mm, at spacing 50 to 200 mm.
R4 Grooves or undulations of depth greater than 10, width > 10mm, at spacing 50 to
200 mm.
Parameters for defining shaft wall roughness (after Horvath et al., 1980 and Kodikara et al., 1992)
Upper and lower bound guidelines for effective roughness adapted from (Seidel and Collingwood, 2001)

Factors related to drilled shaft geometry
Unit side shear versus displacement for drilled shafts socket in rock with qu = 3 MPa (after Baycan, 1996)

Factors related to the load test method
Comparison of typical Load-Displacement behavior four test procedures (adapted from Fellenius, 1975)
0
20
40
60
80
100
120
140
160
180
0 1 2 3 4 5 6 7 8
Load
Displacement
CRP
Quick
ML
Cyclic

Reference α β C
1 Rosenberg and Jouneaux (1976) 0.34 0.51 1.05
2 Horvath (1978) 0.33 0.50 1.04
3
Horvath and Kenney (1979) lower
bound
0.21 0.50 0.65
Horvath and Kenney (1979) upper
bound
0.25 0.50 0.78
4 Meigh and Wolski (1979) 0.22 0.60 0.55
5 Reynolds and Kaderabek (1980) 0.30 1.00 0.30
6 Pells et al. (1980) R1, R2 & R3 0.40 0.50 1.26
Pells et al. (1980) R4 0.80 0.50 2.52
7 Williams et al. (1980) 0.44 0.37 1.85
8 Horvath (1982) smooth 0.20 0.50 0.63
9 Horvath (1982) roughness 0.30 0.50 0.95
10 Gupton and Logan (1984) 0.20 1.00 0.20
Reference α β C
11 Rowe and Armitage (1984) smooth 0.45 0.50 1.42
Rowe and Armitage (1984)
roughness
0.60 0.50 1.89
12 Reese and O'Neill (1987) 0.15 1.00 0.15
13 Carter and Kulhawy (1988) 0.2 0.50 0.63
14 Toh et al. (1989) 0.25 1.00 0.25
15 Kulhawy and Phoon (1993) 0.35 0.50 1.10
16 O'Neill and Reese (1999) 0.21 0.50 0.66
17
Zhang and Einstein (1998) lower
bound
0.20 0.50 0.63
Zhang and Einstein (1999) upper
bound
0.40 0.50 1.26
18 Prakoso (2002) lower bound 0.20 0.50 0.63
Prakoso (2002) upper bound 0.32 0.50 1.00
19 Kulhawy et al. (2005) 0.32 0.50 1.00
20 Turner (2006) 0.32 0.50 1.00
Summary of relations between t and qu (expanded version from O’Neill et al., 1996)

Unit end bearing resistance
Design Method 𝜶 𝒃 𝜷 𝒃
Teng (1962) [5-8] 1
Coates (1967) 3 1
Rowe and Armitage (1987) 2.7 1
Zhang and Einstein (1998) 4.5 1
ARGEMA (1992) [3-6.6] 0.5
Empirical relationships between 𝑞 𝑢 and 𝑞 𝑚𝑎𝑥(expanded version from Zhang & Einstein, 1998)
• Between 10% - 20% (Williams et al., 1980; Carter & Kulhawy, 1988)
• A significant relative movement between concrete and rock is necessary to achieve
the total end bearing resistance (Qb)
• Some methods proposed for predict (Qb) are based on elastic solutions and depend
on the embedment ratio (L/B) and the rate of stiffness (Ec/Er)
Theoretical base load transfer (adapted from Rowe and Armitage, 1987b)
𝑞 𝑚𝑎𝑥 = 𝛼 𝑏 𝑞 𝑢
𝛽 𝑏

Weak rock / IGM’s definition
Weak
rock
Weathered
and broken
rock (BS,
8004)
Indurated
soil
(Oliveira,
1993)
Soft rock
(Johnston,
1989)
Intermediate
geo-material
IGM
(FHWA, 1995)
IGM strength classification based on qu versus 𝝉 𝒎𝒂𝒙 (adapted from Kulhawy and Phoon, 1993)

Summary
• Demand of loads of great magnitude
• 1976 – 2006
• Range of estimation to predict Qs 86% – 93%
• The 27.5% geomorphology area of Puerto Rico is conformed
fro three karst zones (North, South and disperse)
• $ versus capacity
0
5
10
15
20
25
30
10 30 50 70 90 110 130 150
τmax/Pa
qu/Pa
Rosenberg and Jouneaux (1976)
Horvath (1978)
Horvath and Kenney (1979) lower bound
Horvath and Kenney (1979) upper bound
Meigh and Wolski (1979)
Reynolds and Kaderabek (1980)
Pells et al. (1980) R1, R2 & R3
Pells et al. (1980) R4
Williams et al. (1980)
Horvath (1982) smooth
Horvath (1982) roughness
Gupton and Logan (1984)
Rowe and Armitage (1984) smooth
Rowe and Armitage (1984) roughness
Reese and O'Neill (1987)
Carter and Kulhawy (1988)
Toh et al. (1989)
Kulhawy and Phoon (1993)
O'Neill and Reese (1999)
Zhang and Einstein (1998) lower bound
Zhang and Einstein (1999) upper bound
Prakoso (2002) lower bound
Kulhawy et al. (2005)
Turner (2006)

Site Characterization
• Location
General location map of test site not to scale (adapted from www.mapsof.net © 2012)
Aerial image showing location of experimental farm La Montaña (from Google Earth ©2012)
Aerial images showing general location of test site (from Google Earth © 2012)

Geology
Geological map of Puerto Rico (adapted from Renken et al., 2002)
Elevation view of the North Coast Belt of Puerto Rico (adapted from Renken et al., 2002)
Ta

Engineering properties
Drilled shafts load test and site investigation layout (not to scale)
Thermo-gravimetric analyses (TGA) of Aymamón limestone

18
Boring log DS_A2
Drilled shafts load test and site investigation layout (not to scale)
Stress-Strain diagram for Aymamón limestone (UCS) test

Field test program
19
General test layout
Layout of load test arrangement
Setup and arrangement of axial compressive load test

Field test program
20
Field test program
1
2
0
10
20
30
40
50
60
70
0 50 100 150 200 250 300
time(min) Load (kips)
Duration of Load Test
0
5
10
15
20
25
30
0 50 100 150 200 250 300
time(sec) Load (kips)
Duration of Load Test

Field test program
Construction of drilled shafts
1
2
DS_LT 1
DS_LT 2
0
5
10
15
20
0.1 1 10 100 1000
Effectiveheightofroughness-Δr(mm)
qu (Mpa)
Upper Border
Bottom Border
DS_LT 1
DS_LT 2
DS_LT 1
Parameter Values Reference Roughness
Classification R3 Pells et al (1980) Medium to high
RF 0.20 Horvath et al (1980) Low to medium
hm 4.67 mm
Kodikara et al (1992) Medium
isd 5.51
Δre 4.67
Seidel y Collingwood
(2001)
See Figure
DS_LT 2
Parameter Values Reference Roughness
Classification R3 Pells et al (1980) Medium to high
RF 0.21 Horvath et al (1980) Low to medium
hm 4.78 mm
Kodikara et al (1992) Medium
isd 5.20
Δre 4.78
Seidel y Collingwood
(2001)
See Figure
Effective height roughness versus qu for drilled shafts DS_LT1 and DS_LT2
(after Seidel and Collingwood, 2001)
Summary of roughness parameters for drilled shafts DS_LT 1 and
DS_LT 2Summary of roughness parameters for drilled shafts DS_LT 1
and DS_LT 2

Field test program
22
Construction of drilled shafts

Results
23
DS_LT1
0.974
0.0
0.2
0.4
0.6
0.8
1.0
1.2
0 50 100 150 200 250 300
Displacementoftoppile(in)
Load (kips)
1 sequence
2 sequence
3 sequence
Load versus displacement for the drilled shaft DS_LT 1
0
200
400
600
800
1,000
1,200
0 50 100 150 200 250 300
µstrain
Load (kips)
EGP1 (µɛ) level
46.25 in
EGP2 (µɛ) level
34.35 in
EGP3 (µɛ) level
21.75 in
EGP4 (µɛ) level
9.75 in
EGP5 (µɛ) level -
4.25 in
Load applied versus strains for drilled shaft DS_LT 1

Results
DS_LT2
Load versus displacement for the drilled shaft DS_LT 2
0.773
0.0
0.2
0.4
0.6
0.8
1.0
1.2
0 50 100 150 200 250 300
Displacementoftoppile(in)
Load (kips)
0
200
400
600
800
1,000
1,200
0 50 100 150 200 250 300
µstrain
Load (kips)
EGP1 (µɛ) level
49.5 in
EGP2 (µɛ) level
36.5 in
EGP3 (µɛ) level
23.25 in
EGP4 (µɛ) level 9.5
in
EGP5 (µɛ) level -4.5
in
Load applied versus strain for drilled shaft DS_LT 2

Results
250.56
12.85
-12
0
12
24
36
48
60
0 100 200 300
Depth(in) Load (kips)
Q= 15 kips
Q= 25 kips
Q= 40 kips
Q= 45 kips
Q= 65 kips
Q= 100 kips
Q= 165 kips
Q= 215 kips
Q= 250 kips
Qs max
Qs min
Load distributions for drilled shaft DS_LT 1
272.20
5.46
-12
0
12
24
36
48
60
0 100 200 300
Depth(in)
Load (kips)
Q= 10 kips
Q= 25 kips
Q= 35 kips
Q= 45 kips
Q= 65 kips
Q= 100 kips
Q= 150 kips
Q= 200 kips
Q= 230 kips
Q= 250 kips
Q= 270 kips
Q max
Q min
Load distributions for drilled shaft DS_LT 2

Results
Maximum skin friction mobilized for drilled shaft DS_LT 1 Maximum skin friction mobilized for drilled shaft DS_LT 2
0
10
20
30
40
50
0 200 400 600
Depth(in)
Unit side shear resistance mobilized (psi)
Q=20 kips
Q=25 kips
Q=45 kips
Q= 67 kips
Q= 100 kips
Q= 165 kips
Q= 215 kips
Q= 250 kips
0
10
20
30
40
50
0 200 400 600
Depth(in)
Unit side shear resistance mobilized (psi)
Q= 272 kips
Q= 200 kips
Q= 150 kips
Q= 100 kips
Q= 75 kips
Q= 50 kips
Q= 25 kips
Q= 10 kips

Comparative prediction - measured
275
250
333.21
49.01
0
100
200
300
400
500
600
700
800
150 350 550 750 950 1150 1350
Drilledshaftloadcapacity-Qu(psi)
Unconfined compressive strength - qu (psi)
Carter and Kulhawy (1988)
Pells et al. (1980) R4
Limestone
DS_LT 2 (Q measured)
DS_LT 1 (Q measured)
Qu DS_LT 2 est
Qu DS_LT 1 est
Qtu e

Conclusions
• Shafts roughness index factor
• Shaft geometry - diameter and length
• Rate of load method
• Classification of limestone from the Aymamón formation in La
Montana farm
• Pells et al. (1980). – other correlations
• The behavior of the drilled shafts tested
• Future work – La Montana farm

Acknowledgments
• Family
• Geo-Cim Inc, Dywidag-Systems International, MS Drills, Structural Steel
Manufacturing, Inc.
• Mr. Añeses and all the people which work in the La Montaña farm
• Augusto Ortiz, Manuel Collazo
• Dr. Ricardo Ramos, Dr. Daniel Wendichansky, and Dr. Miguel Pando
• Friends
• PRSN – Christa and Victor
• Finally, thanks Ana, André & Mateo
Puerto Rico Seismic Network (PRSN) – January 17th, 2012
29

Puerto Rico Seismic Network (PRSN) – January 17th, 2012
30

Thesis_Jun7_2012

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