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

Effective, Practical, Economic 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

Effective, Practical, Economic 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

Effective, Practical, Economic 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 displacement of either individual piles or pile groups. The materials of the pile need also to be reasonably stressed and not used wastefully.



12

Effective, Practical, Economic 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 displacement of either individual piles or pile groups. The materials of the pile need also to be reasonably stressed and not used wastefully. “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

Effective, Practical, Economic 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 displacement of either individual piles or pile groups. The materials of the pile need also to be reasonably stressed and not used wastefully.

“bearing capacity” RESISTANCE

“displacement” STIFFNESS


SUGGESTIONS BY THEORY

lim,so

lim,bpp

lim

2opp

2op

lim,blim,slim

2olim,blim,b

olim,slim,s

qr

L2q

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

olim,b

pp

lim qr

L2q

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

81

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

dG

L)

L/d

Qb/Q

L/d


18




Q/(w

dG

L)

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.

25.1d

Lc


19




Q/(w

dG

L)

L/d

Qb/Q

L/d

%5Q

Q4025,1

d

L

MPa 30G

MPa 30000Ebc

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]lo

ad

[M

N]Mandolini et al. (2002)



22

0.0

1.0

2.0

3.0

0 20 40 60 80


ad

[M

N]

wlim = 10% d = 60 mm

Q = 1,2 MN FS = 2.7

Rlim = 3,2 MN

Mandolini et al. (2002)


0.0

1.0

2.0

3.0

0 20 40 60 80


ad

[M

N]

Santa Cruz, Bolivia, 2015 Alessandro Mandolini – Sustainable Piling Engineering

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]

de

pth

, z [m

]

Lc

FS = 2,7 m 19L3225,1d

L

MPa 40G

MPa 26500Ec

c

L

p



0.0

1.0

2.0

3.0

0 20 40 60 80


ad

[M

N]


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]

de

pth

, z [m

]

Lc

FS = 2,7

0

5

10

15

20

25

0.0 1.0 2.0 3.0

axial load, N [MN]

de

pth

, z [m

]

Rb,lim

Rs,lim

FS = 1



Longer and/or slender piles more effective in terms of specific capacity.

lim,s

olim,b

pp

lim qr

L2q

L

1

W

R

CONFLICTING NEEDS

d

L

L

Ltanh

1

81

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

http://www.geoforum.com/

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

Battuto.exe

trivellato2.exe

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)

Battuto.exe

trivellato2.exe

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)

Battuto.exe

trivellato2.exe

Poulos et al. (2001)

Some “distilled” suggestions!!!!

-method qs,lim = v

-method: qs,lim = cu

LITERATURE REVIEW: SHAFT RESISTANCE


34



35

-method

= 0.5k0v for ND piles in sand = 2.0k0v for D piles in sand 400%



36

-method

-method

= 0.5k0v for ND piles in sand = 2.0k0v for D piles in sand

D/ND = 1.4 piles in clay

400%

40%

LITERATURE REVIEW: BASE RESISTANCE


37

Test data: qb,lim(D) = (2.43.0)qb,lim(ND) at w = 5%d qb,lim(D) = (1.61.8)qb,lim(ND) at w = 10%d 160300%

Lee and Salgado, 1999: piles in sand

LITERATURE REVIEW: BASE RESISTANCE


38

Test data: qb,lim(D) = (2.43.0)qb,lim(ND) at w = 5%d qb,lim(D) = (1.61.8)qb,lim(ND) at w = 10%d 160300%


Any piles in fine grained soils: qb,lim = 9cu + 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 Alessandro Mandolini – Sustainable Piling Engineering

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




46

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 ND – CFA 37,5 ( 3) 0,25 Rlim as measured at w = 10%d




47

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 ND – CFA 37,5 ( 3) 0,25 D - Franki 73,1 ( 6) 0,08 Rlim as measured at w = 10%d




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) Non Displacement type: - bored (dry, bentonite, temporary steel casing) - 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 = (EpAp)/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.



0

20

40

60

80

CF

A

CF

A

CF

A

CF

A

CF

A

CF

A

CF

A

DR

IVE

N

DR

IVE

N

BO

RE

D

CO

V(K

/ K

C)

[%]

0,0

0,5

1,0

1,5

2,0

CF

A

CF

A

CF

A

CF

A

CF

A

CF

A

CF

A

DR

IVE

N

DR

IVE

N

BO

RE

D

K / K

C


53

0

20

40

60

80

CF

A

CF

A

CF

A

CF

A

CF

A

CF

A

CF

A

DR

IVE

N

DR

IVE

N

BO

RE

D

CO

V(K

/ K

C)

[%]

0,0

0,5

1,0

1,5

2,0

CF

A

CF

A

CF

A

CF

A

CF

A

CF

A

CF

A

DR

IVE

N

DR

IVE

N

BO

RE

D

K / K

C



Data grouped within homogeneous geotechnical area

0

20

40

60

80

CF

A

CF

A

CF

A

CF

A

CF

A

CF

A

CF

A

DR

IVE

N

DR

IVE

N

BO

RE

D

CO

V(K

/ K

C)

[%]

0,0

0,5

1,0

1,5

2,0

CF

A

CF

A

CF

A

CF

A

CF

A

CF

A

CF

A

DR

IVE

N

DR

IVE

N

BO

RE

D

K / K

C

0

20

40

60

80

CF

A

CF

A

CF

A

CF

A

CF

A

CF

A

CF

A

DR

IVE

N

DR

IVE

N

BO

RE

D

CO

V(K

/ K

C)

[%]

0,0

0,5

1,0

1,5

2,0

CF

A

CF

A

CF

A

CF

A

CF

A

CF

A

CF

A

DR

IVE

N

DR

IVE

N

BO

RE

D

K / K

C

1,4

35%


54



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




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 ( 6d) distance

0 10

20

[ r .p .m .]

0 25

0

50

0

VP

[m /h ]

0 10

20

[ r .p .m .]

0 25

0

50

0

VP

[m /h ]

0

10

20

30

0 10

20

30

qc [M Pa]

de

pth

[m

]

0

10

20

30

0 10

20

30

qc [M Pa]

de

pth

[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 [M

N]

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 [M

N]

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 [M

N]

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 [M

N]

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



? ?


64

0 10

20

[ r .p .m .]

0 25

0

50

0

VP

[m /h ]

0 10

20

[ r .p .m .]

0 25

0

50

0

VP

[m /h ]

0

10

20

30

0 10

20

30

qc [M Pa]

de

pth

[m

]

0

10

20

30

0 10

20

30

qc [M Pa]

de

pth

[m

]

0 10

20

[ r .p .m .]

0 25

0

50

0

VP

[m /h ]

0 10

20

[ r .p .m .]

0 25

0

50

0

VP

[m /h ]

0

10

20

30

0 10

20

30

qc [M Pa]

de

pth

[m

]

0

10

20

30

0 10

20

30

qc [M Pa]

de

pth

[m

]

0 10

20

[ r .p .m .]

0 25

0

50

0

VP

[m /h ]

0 10

20

[ r .p .m .]

0 25

0

50

0

VP

[m /h ]

0

10

20

30

0 10

20

30

qc [M Pa]

de

pth

[m

]

0

10

20

30

0 10

20

30

qc [M Pa]

de

pth

[m

]

0 10

20

[ r .p .m .]

0 25

0

50

0

VP

[m /h ]

0 10

20

[ r .p .m .]

0 25

0

50

0

VP

[m /h ]

0

10

20

30

0 10

20

30

qc [M Pa]

de

pth

[m

]

0

10

20

30

0 10

20

30

qc [M Pa]

de

pth

[m

]

0,0

1,0

2,0

3,0

4,0

5,0

0 20 40 60 80

load [M

N]

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 [M

N]

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




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 25

0

50

0

VP

[m /h ]

0 10

20

[ r .p .m .]

0 25

0

50

0

VP

[m /h ]

0

10

20

30

0 10

20

30

qc [M Pa]

de

pth

[m

]

0

10

20

30

0 10

20

30

qc [M Pa]

de

pth

[m

]

0 10

20

[ r .p .m .]

0 25

0

50

0

VP

[m /h ]

0 10

20

[ r .p .m .]

0 25

0

50

0

VP

[m /h ]

0

10

20

30

0 10

20

30

qc [M Pa]

de

pth

[m

]

0

10

20

30

0 10

20

30

qc [M Pa]

de

pth

[m

]

0 10

20

[ r .p .m .]

0 25

0

50

0

VP

[m /h ]

0 10

20

[ r .p .m .]

0 25

0

50

0

VP

[m /h ]

0

10

20

30

0 10

20

30

qc [M Pa]

de

pth

[m

]

0

10

20

30

0 10

20

30

qc [M Pa]

de

pth

[m

]

0,0

1,0

2,0

3,0

4,0

5,0

0 20 40 60 80

load [M

N]

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 [M

N]

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


De

co

mp

ressio

n a

lon

g t

he

en

tire

p

ile

sh

aft

an

d a

t th

e p

ile

ba

se

C

om

pe

nsa

tion

alo

ng

the

en

tire p

ile s

ha

ft a

nd

de

co

mp

ressio

n a

t the

pile

ba

se


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”


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CATEGORY TYPE PERCENTAGE TOTAL

DP

SCREW 7

51 PREFABRICATED 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

% o

f pile t

ype

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 = 80120 cm) of the large diameter bored piles”

30%


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DP

SCREW 7

51 PREFABRICATED 33


NDP BORED 26

49 CFA 23


0

20

40

60

80

100

1984 1985 1986 1987 1988 1989 1990 1991 1992

% o

f pile t

ype

non displ. piles

auger piles

displ. piles

ITALIAN PILE MARKET Trevisani, 1992


DP

SCREW 7

51 PREFABRICATED 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……”


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REPERCUSSION IN OTHER PILE MARKET


75

+50% +40%




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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.”


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78

A QUESTION



Two examples: CFA and FDP


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DP

SCREW 7

51 PREFABRICATED 33


NDP BORED 26

49 CFA 23

DISCREPILE FDP FUNDEX OMEGA


Remarkable differences countries by countries


80


DP

SCREW 7

51 PREFABRICATED 33


NDP BORED 26

49 CFA 23



Increasingly used in European (for instance, Belgium over 60%) and Asian market


81


DP

SCREW 7

51 PREFABRICATED 33


NDP BORED 26

49 CFA 23


vibration and noise free; no soil support; no soil removal no dumping



82


DP

SCREW 7

51 PREFABRICATED 33


NDP BORED 26

49 CFA 23


MORE ENVIRONMENTALLY-FRIENDLY



83


DP

SCREW 7

51 PREFABRICATED 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.


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FDP - RESEARCH IN ITALY

Reseaarch Agreement between: - SUN (Second University of Naples) - ICOTEKNE S.p.A. (Piling Contractor) - BAUER – ITALIA (Piling Equipment)

BAUER FDP JACKED

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


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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


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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


Lesson learned from experiments and theoretical studies about D-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


Lesson learned from experiments and theoretical studies about D-pile (jacked). On the overall, ...... then reduces to values smaller than geostatic ......

loose medium dense


89


Lesson learned from experiments and theoretical studies about D-pile (jacked). On the overall, ...... 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


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Installation energy for jacked and screw piles

vA

TvFE

b

(Van Impe 1994)

Jacked ( = 0):

Screw FDP:

vA

TvF

vA

TvFE

bb

bb A

F

vA

vFE


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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

(kN

m/m

3/

kN)

n (-)

Infisso

FDP

For looser sandy soils (n), jacked piles are less effective (E/Qlim )

porosity, n (-)

jacked


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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

(kN

m/m

3/

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)


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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.



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Scientific approaches to pile design have advanced enormously in 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.



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Scientific approaches to pile design have advanced enormously in 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


When favorable circumstances occur, the number of piles needed to guarantee satisfactory response of the overall foundation system significantly reduces (piled raft concept) economic. Less piles, strategically located beneath raft (3070% less) even more economic and environmentally-friendly design.



102


When favorable circumstances occur, the number of piles needed to guarantee satisfactory response of the overall foundation system significantly reduces (piled raft concept) economic. Less piles, strategically located beneath raft (3070% 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.



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

EN

ER

GY

PR

OD

UC

ER

S

SE

ISM

IC D

EM

AN

D R

ED

UC

ER

S

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


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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

MORE SUSTANAIBILITY

Prof. Ing. Alessandro Mandolini, Ph.D.

SUSTANAIBLE PILING ENGINEERING

Ingeniería sostenible de fundaciones profundas alessandro mandolini

Engineering

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