Ingeniería sostenible de fundaciones profundas alessandro mandolini

Prof. Ing. Alessandro Mandolini, Ph.D.
SUSTANAIBLE PILING
ENGINEERING

SUSTAINABILITY
Sustainable development consists of balancing local and global
efforts to meet basic human needs (social, economic) without
destroying or degrading the natural environment.
Santa Cruz, Bolivia, May 2015
Alessandro Mandolini – Sustainable Piling Engineering
2

SUSTAINABILITY FOR FOUNDATION ENGINEERING
It contributes to social growth by means of cost-effective and
environmentally-friendly foundation system for different
structures and infrastructures.
3

It contributes to social growth by means of cost-effective and
environmentally-friendly foundation system for different
structures and infrastructures.
When dealing with pile foundations, the more suitable foundation
system is that where piles are:
- EFFECTIVE
- PRACTICAL
- ECONOMIC
4
SUSTAINABILITY FOR FOUNDATION ENGINEERING

REQUIREMENTS FOR A GOOD PILE DESIGN
5
Effective, Practical, Economic
Piles must carry the loads that the supported structure imparts
to them, together with any additional forces that may result from
deformations of the soil mass in which they are embedded.
Piles must also be sound, durable and free from significant
defects.
Their design must recognize fully the properties of the ground and
the implications of groundwater movements so that deformations
or settlements will not cause unacceptable strains in the
supported or adjacent structures.

6
Piles must be of a type that will permit access for piling
equipment to the locations where they are required.
The design must recognize the limits of what is possible in current
practice with regard to the equipment available.
The method of construction must recognize and seek to minimize
difficulties related to ground conditions that could impede proper
construction.

7
Design should maximize the bearing capacity of each pile while
at the same time providing for an adequate margin of safety
against failure or excessive deformation of either individual piles
or pile groups.
The materials of the pile need also to be reasonably stressed and
not used wastefully.

EXAMPLE OF UNECONOMIC PILES
Schmertmann & Hayes (1997)
8

Underestimated ultimate load
values lead to higher overall
costs for the foundation ......
9

...... as well as wasted energy
for piling equipment
(not environmentally-friendly).
10

11
against failure or excessive displacement of either individual piles
or pile groups.

12
or pile groups.
“Maximize” has not to be intended as “the maximum possible
bearing capacity” but as “the bearing capacity needed for a given
project with a minimum cost”.
At the same time, the settlement should not be as low as possible
but simply smaller than some acceptable value.

13
or pile groups.
“bearing capacity”  RESISTANCE
“displacement”  STIFFNESS

SUGGESTIONS BY THEORY


















lim,s
o
lim,b
pp
lim
2
opp
2
op
lim,blim,slim
2
olim,blim,b
olim,slim,s
q
r
L
2q
L
1
W
R
rLWrLV
RRR
rqR
Lr2qR
Rlim
qs,lim
qb,lim
Axial soil-pile resistance, Rlim
Specific pile capacity = pile capacity per unit pile weight
14

Rlim
qs,lim
qb,lim
Axial soil-pile resistance, Rlim
It can be shown that the ratio Rlim/Vp attains a
maximum when L/ro  0 or .
It implies that longer and/or slender piles are
more effective in terms of specific capacity.













 lim,s
o
lim,b
pp
lim q
r
L
2q
L
1
W
R
15

Axial soil-pile stiffness, K = Q/w
16

 
 
 
 
   
 
  dLL22L
dr2ln
L25.015.225.0r
GE
GG
GG
dd
d
L
L
Ltanh
1
8
1
d
L
L
Ltanh2
1
2
Gdw
Q
m
m
Lp
L
bL
b
L

























Ratio of underream:
Soil stiffness ratio at pile base:
Degree of soil stiffness homogeneity:
Pile-soil relative stiffness:
Radius of influence of pile:
Measure of radius of influence of pile:
Measure of pile compressibility:
17
Randolph & Wroth (1978); Fleming et al. (1992)

There are combinations of slenderness ratio (L/d) and stiffness
ratio () beyond which very little load is transmitted to the pile
base.
Further increase in pile length yields no corresponding increase in
the load settlement ratio of the pile.
Q/(wdGL)
L/d
Qb/Q
L/d
18

Q/(wdGL)
L/d
Qb/Q
L/d
A critical pile length Lc (or a critical slenderness ratio Lc/d) exists
beyond which extending pile is useless in practice if settlement
has to be reduced.
 25.1
d
Lc
19

Q/(wdGL)
L/d
Qb/Q
L/d
%5
Q
Q
4025,1
d
L
MPa30G
MPa30000E bc
L
p






20

VALIDATION BY EXPERIMENTS
21
Non Displacement pile: CFA type (L = 24 m; d = 0,60 m)
0.0
1.0
2.0
3.0
0 20 40 60 80
settlement, w [mm]
load[MN]
Mandolini et al. (2002)

22
0.0
1.0
2.0
3.0
0 20 40 60 80
settlement, w [mm]
load[MN]
wlim = 10% d = 60 mm
Q = 1,2 MN
FS = 2.7
Rlim = 3,2 MN

0.0
1.0
2.0
3.0
0 20 40 60 80
settlement, w [mm]
load[MN]
Santa Cruz, Bolivia, 2015
23
wlim = 10% d = 60 mm
Q = 1,2 MN
FS = 2.7
Rlim = 3,2 MN
0
5
10
15
20
25
0.0 1.0 2.0 3.0
axial load, N [MN]
depth,z[m]
Lc
FS = 2,7 m19L3225,1
d
L
MPa40G
MPa26500E
c
c
L
p







0.0
1.0
2.0
3.0
0 20 40 60 80
settlement, w [mm]
load[MN]
24
wlim = 10% d = 60 mm
Q = 1,2 MN
FS = 2.7
Rlim = 3,2 MN
0
5
10
15
20
25
0.0 1.0 2.0 3.0
axial load, N [MN]
depth,z[m]
Lc
FS = 2,7
0
5
10
15
20
25
0.0 1.0 2.0 3.0
axial load, N [MN]
depth,z[m]
Rb,lim
Rs,lim
FS = 1

Longer and/or slender piles
more effective in terms of
specific capacity.













 lim,s
o
lim,b
pp
lim q
r
L
2q
L
1
W
R
CONFLICTING NEEDS
 
 
 
 
d
L
L
Ltanh
1
8
1
d
L
L
Ltanh2
1
2
Gdw
Q
L 

















Shorter and/or stubby piles
more effective in terms of
load-settlement ratio.
25
REMARKS

26
REMARKS
Fulfilling the opposite needs
becomes more and more
complicated if installation
effects are considered.

It offers a great number of pile types, forcing engineers to be
continuously updated about new available technologies.
WORLD PILE MARKET
27

It offers a great number of pile types, forcing engineers to be
continuously updated about new available technologies.
“SOME” PILE TYPE (source www.geoforum.com)
Alpha Pile, Atlas Pile, Bade System, Benoto System, Brechtl System, Button-
bottom Pile, Casagrande System, Compressol Pile, Continuous Flight Auger (CFA)
System, Daido SS Pile, Delta Pile, Drill-and-drive Pile, Franki Composite Pile,
Franki Excavated Pile, Franki Pile, Franki Pile with casing top driven, Franki VB
Pfahl, Fundex Pile, Held-Franke System, Hochstrasser-Weise System, Hollow
precast concrete pile with timber/steel core, Icos Veder System, Jointed Concrete
Pile, Lacor Pile, Large diameter bored pile, Lind-Calweld Pile, Lorenz Pile, Mast
System, Millgard Shell Pile, Mini pile, Monierbau Pile, Multiton Pile, MV-pile,
Omega Pile, Pieux Choc, Precast Concrete Pile, Precast Reinforced Concrete Pile,
Pressodrill, Prestcore, Prestressed Concrete Pile, Raymond Pile, Rolba Pile, Sheet
Pile, Simplex System, Small diameter bored pile, Soilex System, Starsol Pile, Steel
Box Pile, Steel pile, Steel Tube Pile, Steel-concrete (SC) Composite Pile, Steel-H
Pile, SVB Pile, SVV Pile, Timber Pile, Tubex Pile, Westpile Shell Pile, Vibrex Cast-
In-Situ Pile, Wolfholz System, X-pile, Zeissl System, …………
WORLD PILE MARKET
28

WORLD PILE MARKET
29
PILE CLASSIFICATION
Modified from Fleming et al., 2009

WORLD PILE MARKET
30
PILE CLASSIFICATION
Modified from Fleming et al., 2009

WORLD PILE MARKET
31
PILE CLASSIFICATION
Soil is laterally displaced
during the insertion of pile,
increasing total stress into
the surrounding soil
Soil is removed and
substituted by the pile,
decreasing (at the best,
leaving practically
unchanged) total stress into
the surrounding soil

WORLD PILE MARKET
32
PILE CLASSIFICATION
DP tends to exhibit much greater resistance than NDP due
to the improvements into the surrounding soil (greater
effective stresses  lower porosity and greater strength)
SANDY OR
GRAVELLY SOILS
(drained response)

WORLD PILE MARKET
33
PILE CLASSIFICATION
DP and NDP tends to exhibit comparable resistance due to
limited changes in effective stresses and constant porosity
condition
CLAYEY AND
SILTY SOILS
(undrained response)

Poulos et al. (2001)
Some “distilled”
suggestions!!!!
-method
qs,lim = v
-method: qs,lim = cu
LITERATURE REVIEW: SHAFT RESISTANCE
34

35
-method
 = 0.5k0v for ND piles in sand
 = 2.0k0v for D piles in sand 400%

36
-method
-method
 = 0.5k0v for ND piles in sand
 = 2.0k0v for D piles in sand
D/ND = 1.4 piles in clay
400%
40%

LITERATURE REVIEW: BASE RESISTANCE
37
Test data:
qb,lim(D) = (2.43.0)qb,lim(ND) at w = 5%d
qb,lim(D) = (1.61.8)qb,lim(ND) at w = 10%d 160300%
Lee and Salgado, 1999: piles in sand

LITERATURE REVIEW: BASE RESISTANCE
38
Test data:
qb,lim(D) = (2.43.0)qb,lim(ND) at w = 5%d
qb,lim(D) = (1.61.8)qb,lim(ND) at w = 10%d 160300%
Any piles in fine grained soils: qb,lim = 9cu + vL

REMARKS
39
DP installed in coarse grained soils
(gravel/sand) are expected to have greater axial
resistance than NDP due to positive effects both
at the pile shaft and at the pile base.
Independently from the installation method,
piles embedded in fine grained soils (clay/silt)
are expected to have similar axial resistance.

REMARKS
40
DP installed in coarse grained soils
(gravel/sand) are expected to have greater axial
resistance than NDP due to positive effects both
at the pile shaft and at the pile base.
MORE ATTENTION ON PILE TECHNOLOGY
Independently from the installation method,
piles embedded in fine grained soils (clay/silt)
are expected to have similar axial resistance.
MORE ATTENTION TO SOIL PROPERTIES

Santa Cruz, Bolivia, 2015
41
VESUVIO
BAY OF NAPLES
EXPERIMENTAL EVIDENCE COLLECTED IN ITALY

42
VESUVIO
CENTRO DIREZIONALE DI NAPOLI
BAY OF NAPLES
145 load tests on different piles installed in
rather uniform subsoil conditions (SANDY SOILS)

43
VESUVIO
BAY OF NAPLES
20 load tests at failure (w  10%d) on trial piles
125 load tests on production piles

44
20 load tests to failure on trial cast in situ piles (Mandolini et al., 2005)
Non Displacement type:
- bored (dry, bentonite, temporary steel casing)
- CFA
Displacement type:
- Franki
d = 0.35  2.00 m
L = 9.5  42.0 m
L/d = 16  61

45
d = 0.35  2.00 m
L = 9.5  42.0 m
L/d = 16  61
Pile type (Rlim/Wp)av COV(Rlim/Wp)
ND – Bored 12,1 (1) 0,26
Rlim as measured at w = 10%d
- CFA
Displacement type:
- Franki

46
d = 0.35  2.00 m
L = 9.5  42.0 m
L/d = 16  61
ND – Bored 12,1 (1) 0,26
ND – CFA 37,5 ( 3) 0,25
- CFA
Displacement type:
- Franki

47
d = 0.35  2.00 m
L = 9.5  42.0 m
L/d = 16  61
ND – Bored 12,1 (1) 0,26
ND – CFA 37,5 ( 3) 0,25
D - Franki 73,1 ( 6) 0,08
- CFA
Displacement type:
- Franki

48
REMARKS
The method of installation
strongly affects pile response to
axial loading at failure due to
remarkable changes induced into
a thin soil volume close to the pile
In the quoted example, till to 6 times on the average !!

49
REMARKS
The method of installation
strongly affects pile response to
axial loading at failure due to
remarkable changes induced into
a thin soil volume close to the pile
IS IT STILL VALID FOR
AXIAL PILE STIFFNESS ?

50
VESUVIO
BAY OF NAPLES
20 load tests at failure (w  10%d) on trial piles
125 load tests on production piles

51
125 proof load tests on production cast in situ piles (Mandolini et al., 2005)
- CFA
Displacement type:
- Screw
-Franki

52
The experimentally determined axial soil-pile stiffness K = Q/w
under working load was compared with that of an equivalent
column having a structural axial stiffness Kc = (EpAp)/Lc.
Critical length Lc was chosen in order to compare the stiffness of
the column with that of a pile having only that reduced length
over which it is transferring the applied load to the surrounding
soil.
- CFA
Displacement type:
- Screw
-Franki

80
0,0
0,5
1,0
1,5
2,0
CFA
CFA
CFA
CFA
CFA
CFA
CFA
DRIVEN
DRIVEN
BORED
K/KC
53
0
20
40
60
80
CFA
CFA
CFA
CFA
CFA
CFA
CFA
DRIVEN
DRIVEN
BORED
COV(K/KC)[%]
0,0
0,5
1,0
1,5
2,0
CFA
CFA
CFA
CFA
CFA
CFA
CFA
DRIVEN
DRIVEN
BORED
K/KC
- CFA
Displacement type:
- Screw
-Franki
Data grouped within homogeneous geotechnical area

80
0,0
0,5
1,0
1,5
2,0
CFA
CFA
CFA
CFA
CFA
CFA
CFA
DRIVEN
DRIVEN
BORED
K/KC
0
20
40
60
80
CFA
CFA
CFA
CFA
CFA
CFA
CFA
DRIVEN
DRIVEN
BORED
COV(K/KC)[%]
0,0
0,5
1,0
1,5
2,0
CFA
CFA
CFA
CFA
CFA
CFA
CFA
DRIVEN
DRIVEN
BORED
K/KC
1,4
35%
54
- CFA
Displacement type:
- Screw
-Franki
Data grouped within homogeneous geotechnical area

55
Pile type (Q/w)av COV(Q/w)
ND – Bored 1,46 (1) 0,28
ND – CFA 1,44 ( 1) 0,46
D – Screw, Franki 1,29 ( 0.9) 0,42
Q/w measured at working load
- CFA
Displacement type:
- Screw
-Franki

56
REMARKS
The method of installation strongly affects pile
response to axial loading at failure due to
remarkable changes induced into a thin soil
volume close to the pile

57
REMARKS
The method of installation strongly affects pile
response to axial loading at failure due to
remarkable changes induced into a thin soil
volume close to the pile
AT MUCH LESSER EXTENT
More details, also substantiated by theory, are given in Mandolini et al. (2005)

58
A QUESTION
HOW TO GET THE BEST FOR A
GIVEN COMBINATION OF
PILE AND SOIL TYPE ?

59
A QUESTION
Two examples: CFA and FDP

60
CFA PILES – RESEARCH IN ITALY
SUN won a national competition for a research funding by Italian Government
(about 900.000 €)
Piling Contractor Partner: Società Italiana Fondazioni S.p.A.
4 experimental sites (n.c. and o.c clayey; loose and dense sandy soils)
For each experimental site: detailed geotechnical
investigations
5 load tests at failure on fully
instrumented trial piles installed
with a different set of installation
parameters
different concrete mix

61
Results of loading tests on two identical CFA piles (L = 24 m; d = 0,8 m) installed
by the same piling contractor with the same operator in the same subsoil at less
than 5 m ( 6d) distance
0
10
20
 [r .p .m .]
0
250
500
V P
[m /h ]
0
10
20
 [r .p .m .]
0
250
500
V P
[m /h ]
0
10
20
30
0
10
20
30
q c
[M Pa]
depth[m]
0
10
20
0
10
20
30
q c
[M Pa]
depth[m]
Top soil
Alluvial
Soils
Base
formation
GWL
EXPERIMENTAL RESULTS: POGGIOMARINO SITE

62
0,0
1,0
2,0
3,0
4,0
5,0
0 20 40 60 80
load[MN]
settlement, w [mm]
total load
shaft load
base load
0,0
1,0
2,0
3,0
4,0
5,0
0 20 40 60 80
load[MN]
settlement, w [mm]
4.08 MN
2.81 MN
1.55 MN
5.30 MN
3.94 MN
1.36 MN
w > 10%d  failure
w << 10%d  no failure

63
0,0
1,0
2,0
3,0
4,0
5,0
0 20 40 60 80
load[MN]
settlement, w [mm]
total load
shaft load
base load
0,0
1,0
2,0
3,0
4,0
5,0
0 20 40 60 80
load[MN]
settlement, w [mm]
4.08 MN
2.81 MN
1.55 MN
5.30 MN
3.94 MN
1.36 MN
? ?

64
0
10
20
 [r .p .m .]
0
250
500
V P
[m /h ]
0
10
20
 [r .p .m .]
0
250
500
V P
[m /h ]
0
10
20
30
q c
[M Pa]
0
10
20
30
q c
[M Pa]
0
10
20
 [r .p .m .]
0
250
500
V P
[m /h ]
30
0
10
20
30
0
10
20
30
q c
[M Pa]
depth[m]
0
10
20
30
0
10
20
30
q c
[M Pa]
depth[m]
0
10
20
30
0
10
20
30
q c
[M Pa]
depth[m]
0
10
20
 [r .p .m .]
0
250
500
V P
[m /h ]
0
10
20
 [r .p .m .]
0
250
500
V P
[m /h ]
0
10
20
30
0
10
20
30
q c
[M Pa]
depth[m]
0
10
20
30
0
10
20
30
q c
[M Pa]
depth[m]
0,0
1,0
2,0
3,0
4,0
5,0
0 20 40 60 80
load[MN]
settlement, w [mm]
total load
shaft load
base load
0,0
1,0
2,0
3,0
4,0
5,0
0 20 40 60 80
load[MN]
settlement, w [mm]
4.08 MN
2.81 MN
1.55 MN
5.30 MN
3.94 MN
1.36 MN

65
65
Concrete
Pump
PENETRATION STAGE
Rate of penetration, vP
Rate of revolution, ωP
Viggiani (1989, 1993)
Kinematic analysis: in order not to
decompress surrounding soils:
VP > VP,CR = P[1-(d0/dN)2]
 = pitch of the screw
d0 = outer diameter of the central hollow stem
dN = overall diameter of the auger

66
Concrete
Pump
“net” compressed
soil:
vP >  x 
“net”
decompressed soil:
vP <  x 

67
0
10
20
 [r .p .m .]
0
250
500
V P
[m /h ]
0
10
20
 [r .p .m .]
0
250
500
V P
[m /h ]
0
10
20
30
q c
[M Pa]
0
10
20
30
q c
[M Pa]
0
10
20
 [r .p .m .]
0
250
500
V P
[m /h ]
30
0
10
20
30
0
10
20
30
q c
[M Pa]
depth[m]
0
10
20
 [r .p .m .]
0
250
500
V P
[m /h ]
0
10
20
 [r .p .m .]
0
250
500
V P
[m /h ]
0
10
20
30
0
10
20
30
q c
[M Pa]
depth[m]
0
10
20
30
0
10
20
30
q c
[M Pa]
depth[m]
0,0
1,0
2,0
3,0
4,0
5,0
0 20 40 60 80
load[MN]
settlement, w [mm]
total load
shaft load
base load
0,0
1,0
2,0
3,0
4,0
5,0
0 20 40 60 80
load[MN]
settlement, w [mm]
4.08 MN
2.81 MN
1.55 MN
5.30 MN
3.94 MN
1.36 MN
Decompressionalongtheentire
pileshaftandatthepilebase
Compensationalongtheentirepileshaft
anddecompressionatthepilebase

qs,lim = s  qc,s
qb,lim = b  qc,b
0.02
0.03
0.04
0.0 1.0 2.0VP/VP,CR
S
0.15
0.20
0.25
0.0 1.0 2.0VP/VP,CR
B
s = 0,026 x (VP/VP,CR) + 0,004 b = 0,115 x (VP/VP,CR) + 0,153
68
+50%
+40%

qs,lim = s  qc,s
qb,lim = b  qc,b
b = 0,115 x (VP/VP,CR) + 0,153
69
0.15
0.20
0.25
0.0 1.0 2.0VP/VP,CR
B

Velocity index, IV = VP / VP,crit
Low values for IV determine a
net effect of soil decompression,
thus CFA piles badly installed.
It has to be expected, under
other same conditions, low shaft
and base resistances
“ND pile”
High values for IV determine a
net effect of soil compression,
thus CFA piles conveniently
installed.
It has to be expected, under
other same conditions, high
shaft and base resistances
“D pile”
70

71
CATEGORY TYPE PERCENTAGE TOTAL
DP
SCREW 7
51PREFABRICATED 33
DRIVEN CAST IN PLACE 11
NDP
BORED 26
49
CFA 23
WORLD PILE MARKET (Source DFI, 2006)
Remarkable differences
countries by countries

0
20
40
60
80
100
1984 1985 1986 1987 1988 1989 1990 1991 1992
%ofpiletype
non displ. piles
auger piles
displ. piles
ITALIAN PILE MARKET
Trevisani, 1992
“In the next future, auger
piles will probably gain the
market against the smaller
size (d = 80120 cm) of the
large diameter bored piles”
 30%
72
DP
SCREW 7
51PREFABRICATED 33
NDP
BORED 26
49
CFA 23

0
20
40
60
80
100
1984 1985 1986 1987 1988 1989 1990 1991 1992
%ofpiletype
non displ. piles
auger piles
displ. piles
ITALIAN PILE MARKET
Trevisani, 1992
DP
SCREW 7
51PREFABRICATED 33
NDP
BORED 26
49
CFA 23
73
0
20
40
60
80
100
2000 2001 2002 2003 2004
Mandolini, 2004
 55%
 30%

Report n. FHWA-HIF-07-03
PREFACE:
“CFA piles have been used in the U.S.
commercial market but have not been
used frequently for support of
transportation structures in the United
States. This underutilization of a viable
technology is a result of perceived
difficulties in quality control, and the
difficulties associated with incorporating
a rapidly developing (and often
proprietary) technology into the
traditional, prescriptive design-bid-build
concept……”
74
REPERCUSSION IN OTHER PILE MARKET

75
+50%
+40%

76

PREFACE:
“CFA piles have been used in the U.S.
commercial market but have not been
used frequently for support of
transportation structures in the United
States. This underutilization of a viable
technology is a result of perceived
difficulties in quality control, and the
difficulties associated with incorporating
a rapidly developing (and often
proprietary) technology into the
traditional, prescriptive design-bid-build
concept.
Recent advances in automated
monitoring and recording devices will
alleviate concerns of quality control, as
well as provide an essential tool for a
performance-based contracting process.”
77

78
A QUESTION
Two examples: CFA and FDP

79
DP
SCREW 7
51PREFABRICATED 33
NDP
BORED 26
49
CFA 23
DISCREPILE FDPFUNDEX OMEGA
Remarkable differences countries by countries

80
DP
SCREW 7
51PREFABRICATED 33
NDP
BORED 26
49
CFA 23
Increasingly used in European (for instance,
Belgium over 60%) and Asian market

81
DP
SCREW 7
51PREFABRICATED 33
NDP
BORED 26
49
CFA 23
vibration and noise free; no soil support;
no soil removal  no dumping

82
DP
SCREW 7
51PREFABRICATED 33
NDP
BORED 26
49
CFA 23
MORE ENVIRONMENTALLY-FRIENDLY

83
DP
SCREW 7
51PREFABRICATED 33
NDP
BORED 26
49
CFA 23
Lehane B. (2005): “It is only a matter of time before they
will dominate the market of medium scale bored piles”

Particle Flow
Code 3D v. 3.00
Itasca
Valentino F (2014).
Analysis of installation and loading process for displacement piles by Discrete Element
Model
Ph.D. Thesis, Seconda Università degli Studi di Napoli.
84
FDP - RESEARCH IN ITALY
Reseaarch Agreement between:
- SUN (Second University of Naples)
- ICOTEKNE S.p.A. (Piling Contractor)
- BAUER – ITALIA (Piling Equipment)

BAUER FDPJACKED
Compaction
Stabilisation
Compaction
Perforation
Jacked and Screw piles L = 8,45 m; D = 0,60 m
Horizontal stress changes at the end of insertion h,INS/h0
85

Jacked pile L = 8,45 m; D = 0,60 m
Horizontal stress changes:
- at the end of insertion (INS)
- after removal of jacking load, i.e. End Of Construction (EOC)
- after loading (L) at w = 10%D
loose medium dense
86

Lesson learned from experiments and theoretical studies about D-
pile (jacked). On the overall:
 in medium to dense sand, the soil changes occurred during
the construction envisage the amount of available skin
friction during subsequent loading.
loose medium dense
87

pile (jacked). On the overall,
 in loose sand, the increase of h during the pile insertion over
most of the pile length ......
loose medium dense
88

 ...... then reduces to values smaller than geostatic ......
loose medium dense
89

 ...... and partially recovered during loading stage, often
resulting in values which are close to geostatic (no significant
advantages vs ND-pile in terms of shaft capacity)
loose medium dense
90

Installation energy for jacked and screw piles
vA
TvF
E
b 

 (Van Impe 1994)
Jacked ( = 0):
Screw FDP:










vA
TvF
vA
TvF
E
bb
bb A
F
vA
vF
E 

 



91

Specific Installation Energy (E/Qlim)
0.0
1.0
2.0
3.0
4.0
5.0
6.0
7.0
0.40 0.41 0.42 0.43 0.44 0.45 0.46
E/Qlim(kNm/m3/kN)
n (-)
Infisso
FDP
For looser sandy soils (n), jacked piles are less effective (E/Qlim )
porosity, n (-)
jacked
92

0.0
1.0
2.0
3.0
4.0
5.0
6.0
7.0
0.40 0.41 0.42 0.43 0.44 0.45 0.46
E/Qlim(kNm/m3/kN)
n (-)
Infisso
FDP
jacked
screw FDP
porosity, n (-)
For looser sandy soils (n), jacked piles are less effective (E/Qlim )
The contrary is true for screw FDP (E/Qlim)
93
Specific Installation Energy (E/Qlim)

Theoretical studies like those here presented can
greatly help piling industry in conceiving more
convenient installation procedure and design methods
(i.e., CFA piles) as well as more productive piling
equipment.
94
REMARKS

Theoretical studies like those here presented can
greatly help piling industry in conceiving more
convenient installation procedure and design methods
(i.e., CFA piles) as well as more productive piling
equipment.
Moreover, different shape and size of perforation tools
can be “explored” in advance instead of relying on trial
and error site procedure often managed by site
engineers (and not specialists) to solve a specific
problem on a specific type (not exportable
experience).
95
REMARKS

96
CONCLUDING REMARKS #1

97
Scientific approaches to pile design have advanced enormously in
recent decades.

98
recent decades.
Significant improvements have been made in identifying the
mechanisms developing at soil-pile interface either during the
installation or during loading, allowing for selection of the pile also
on the basis of specific energy consumption  economic,
environmentally-friendly.

99
recent decades.
Significant improvements have been made in identifying the
mechanisms developing at soil-pile interface either during the
installation or during loading, allowing for selection of the pile also
on the basis of specific energy consumption  economic,
environmentally-friendly.
Design of piled foundation based on stiffness consideration is more
reliable because much less affected by technological and site-
construction aspects.

100
When favorable circumstances occur, the number of piles needed to
guarantee satisfactory response of the overall foundation system
significantly reduces (piled raft concept)  economic.

101
Less piles, strategically located beneath raft (3070% less)  even
more economic and environmentally-friendly design.

102
Less piles, strategically located beneath raft (3070% less)  even
more economic and environmentally-friendly design.
If properly selected, piles can ensure high specific capacities (pile
resistance/pile weight); a trend is observed where displacement
(screw) piles are gaining market due to high specific capacities and
low impact on environment.

103
Piles can also play an “active” role in reducing seismic demand or
producing energy satisfy needs  social, economic, environment.
ENERGYPRODUCERS
SEISMICDEMANDREDUCERS

New Hospital in
Monselice, Italy
Full Displacement Screw
Piles conceived as a part of
piled raft in a seismic area
and equipped with
geothermal pipes
FOR A BETTER AND
SUSTANAIBLE
FUTURE
JOINING NOVELTIES
104

105
Despite adverse comments by some of the Pioneers in
Soil Mechanics (and despite attitude of Civil Engineers
to not modify their daily practice), there is a significant
role for scientific methods in pile design.
(Randolph, 2003)
(Mandolini, now)

106
Despite adverse comments by some of the Pioneers in
Soil Mechanics (and despite attitude of Civil Engineers
to not modify their daily practice), there is a significant
role for scientific methods in pile design.
(Randolph, 2003)
(Mandolini, now)
MORE “PURE” APPLIED SCIENCE
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