basic design of stilts based on the cpt julio r. valdes geo-innovations research group civil...
TRANSCRIPT
![Page 1: Basic design of stilts based on the CPT Julio R. Valdes Geo-Innovations Research Group Civil Engineering SDSU](https://reader036.vdocuments.net/reader036/viewer/2022062515/56649cdc5503460f949a7caa/html5/thumbnails/1.jpg)
Basic design of stilts based on the CPT
Julio R. ValdesGeo-Innovations Research Group
Civil EngineeringSDSU
![Page 2: Basic design of stilts based on the CPT Julio R. Valdes Geo-Innovations Research Group Civil Engineering SDSU](https://reader036.vdocuments.net/reader036/viewer/2022062515/56649cdc5503460f949a7caa/html5/thumbnails/2.jpg)
CPT
Parameters
Design – method
Example
![Page 3: Basic design of stilts based on the CPT Julio R. Valdes Geo-Innovations Research Group Civil Engineering SDSU](https://reader036.vdocuments.net/reader036/viewer/2022062515/56649cdc5503460f949a7caa/html5/thumbnails/3.jpg)
CPT
![Page 4: Basic design of stilts based on the CPT Julio R. Valdes Geo-Innovations Research Group Civil Engineering SDSU](https://reader036.vdocuments.net/reader036/viewer/2022062515/56649cdc5503460f949a7caa/html5/thumbnails/4.jpg)
‘coin’
![Page 5: Basic design of stilts based on the CPT Julio R. Valdes Geo-Innovations Research Group Civil Engineering SDSU](https://reader036.vdocuments.net/reader036/viewer/2022062515/56649cdc5503460f949a7caa/html5/thumbnails/5.jpg)
Hydraulic jack
Steel tubes
Continuous penetration at 2 cm/sec
Cone
![Page 6: Basic design of stilts based on the CPT Julio R. Valdes Geo-Innovations Research Group Civil Engineering SDSU](https://reader036.vdocuments.net/reader036/viewer/2022062515/56649cdc5503460f949a7caa/html5/thumbnails/6.jpg)
![Page 7: Basic design of stilts based on the CPT Julio R. Valdes Geo-Innovations Research Group Civil Engineering SDSU](https://reader036.vdocuments.net/reader036/viewer/2022062515/56649cdc5503460f949a7caa/html5/thumbnails/7.jpg)
![Page 8: Basic design of stilts based on the CPT Julio R. Valdes Geo-Innovations Research Group Civil Engineering SDSU](https://reader036.vdocuments.net/reader036/viewer/2022062515/56649cdc5503460f949a7caa/html5/thumbnails/8.jpg)
Parameters
![Page 9: Basic design of stilts based on the CPT Julio R. Valdes Geo-Innovations Research Group Civil Engineering SDSU](https://reader036.vdocuments.net/reader036/viewer/2022062515/56649cdc5503460f949a7caa/html5/thumbnails/9.jpg)
By means of electric sensors,
the CPT provides
Four parameters
Which can be used to calculate
The resitance, stiffness, and In some cases, permeability
Of the soil.
![Page 10: Basic design of stilts based on the CPT Julio R. Valdes Geo-Innovations Research Group Civil Engineering SDSU](https://reader036.vdocuments.net/reader036/viewer/2022062515/56649cdc5503460f949a7caa/html5/thumbnails/10.jpg)
Parameters
fs
qt
Vs
u2
Tip resistance = qt
Sleve friction= fs
Pore Pressure = u2
Shear wave velocity= Vs
![Page 11: Basic design of stilts based on the CPT Julio R. Valdes Geo-Innovations Research Group Civil Engineering SDSU](https://reader036.vdocuments.net/reader036/viewer/2022062515/56649cdc5503460f949a7caa/html5/thumbnails/11.jpg)
Tip resitance
There needs to be a “correction” of qt because the actual values of u are different at the top and at the bottom of the tip.
qT = qt + (1-an)u2
an = 0.8 = fn (cone)
Force sensor
![Page 12: Basic design of stilts based on the CPT Julio R. Valdes Geo-Innovations Research Group Civil Engineering SDSU](https://reader036.vdocuments.net/reader036/viewer/2022062515/56649cdc5503460f949a7caa/html5/thumbnails/12.jpg)
Sleve friction
The “sleve” is forced upward during the test because of the soil-sleve friction
fs
![Page 13: Basic design of stilts based on the CPT Julio R. Valdes Geo-Innovations Research Group Civil Engineering SDSU](https://reader036.vdocuments.net/reader036/viewer/2022062515/56649cdc5503460f949a7caa/html5/thumbnails/13.jpg)
Pore pressureThe pore presure changes during the test because the soil is subjected to forces during penetration..
If k is low, u2 ≠ uh
If k is high, u2 = uh
uh = ahp
hp
During penetration (beneath the ground)
![Page 14: Basic design of stilts based on the CPT Julio R. Valdes Geo-Innovations Research Group Civil Engineering SDSU](https://reader036.vdocuments.net/reader036/viewer/2022062515/56649cdc5503460f949a7caa/html5/thumbnails/14.jpg)
Velocity
Hitting the beam with the hammer creates a shear wave propagates through the soil towards the cone .
A geophone inside of the cone captures the arrival of the wave.
![Page 15: Basic design of stilts based on the CPT Julio R. Valdes Geo-Innovations Research Group Civil Engineering SDSU](https://reader036.vdocuments.net/reader036/viewer/2022062515/56649cdc5503460f949a7caa/html5/thumbnails/15.jpg)
Initial Arrival
(t = tp) Time t
Hammer hit (t = 0)
Velocity
Vs = D / tp
![Page 16: Basic design of stilts based on the CPT Julio R. Valdes Geo-Innovations Research Group Civil Engineering SDSU](https://reader036.vdocuments.net/reader036/viewer/2022062515/56649cdc5503460f949a7caa/html5/thumbnails/16.jpg)
Measurements in real time(computer)
Sand
Clay
Crust
Results (Example)
![Page 17: Basic design of stilts based on the CPT Julio R. Valdes Geo-Innovations Research Group Civil Engineering SDSU](https://reader036.vdocuments.net/reader036/viewer/2022062515/56649cdc5503460f949a7caa/html5/thumbnails/17.jpg)
Design of stilts
![Page 18: Basic design of stilts based on the CPT Julio R. Valdes Geo-Innovations Research Group Civil Engineering SDSU](https://reader036.vdocuments.net/reader036/viewer/2022062515/56649cdc5503460f949a7caa/html5/thumbnails/18.jpg)
Design by analysis
![Page 19: Basic design of stilts based on the CPT Julio R. Valdes Geo-Innovations Research Group Civil Engineering SDSU](https://reader036.vdocuments.net/reader036/viewer/2022062515/56649cdc5503460f949a7caa/html5/thumbnails/19.jpg)
Drilling stilts
![Page 20: Basic design of stilts based on the CPT Julio R. Valdes Geo-Innovations Research Group Civil Engineering SDSU](https://reader036.vdocuments.net/reader036/viewer/2022062515/56649cdc5503460f949a7caa/html5/thumbnails/20.jpg)
Compacting stilts
Brown 2008 Agra foundations 08
![Page 21: Basic design of stilts based on the CPT Julio R. Valdes Geo-Innovations Research Group Civil Engineering SDSU](https://reader036.vdocuments.net/reader036/viewer/2022062515/56649cdc5503460f949a7caa/html5/thumbnails/21.jpg)
layer #1
layer #2
Capacity
L = G1 + G2
Q = Qf + Qp
G1
G2
diameter = d
FS = Load/ Q
Tip capacity
Friction capacity
![Page 22: Basic design of stilts based on the CPT Julio R. Valdes Geo-Innovations Research Group Civil Engineering SDSU](https://reader036.vdocuments.net/reader036/viewer/2022062515/56649cdc5503460f949a7caa/html5/thumbnails/22.jpg)
Calculate for z = L
Tip capacity Qp
Qp = (qp)(Ap)
qp = qT – uh
d2/4 layer #1
layer #2
diameter = d
qp = (qT – ’vo)/k2
Compactor and Drill (Esllami & Fellenius 2006)
Compators in clay (Powell et al. 2001)
L =
G1 +
G2
k2 = 1.7
![Page 23: Basic design of stilts based on the CPT Julio R. Valdes Geo-Innovations Research Group Civil Engineering SDSU](https://reader036.vdocuments.net/reader036/viewer/2022062515/56649cdc5503460f949a7caa/html5/thumbnails/23.jpg)
Friction
T = N
Coefficient of friction (block-floor)
Given the magnitude of N, how large does T have to be for the block to move?
blockT
Weight of block = N
floor
In other words, when T = N , the system fails; FS = 1.
T is the resistance of the system if T = N
![Page 24: Basic design of stilts based on the CPT Julio R. Valdes Geo-Innovations Research Group Civil Engineering SDSU](https://reader036.vdocuments.net/reader036/viewer/2022062515/56649cdc5503460f949a7caa/html5/thumbnails/24.jpg)
layer #1
layer #2
Friction capacity Qf
L = G1 + G2
Qf = (As1)(f1) + (As2)(f2)
f1 = (’ho1) tan(’) CM CK
f1 = Ko1(’vo1) tan(’) CM CK
dG1G1
G2
diameter = d
Needed: G , Ko , vo , ’ , CM , CK
N...for soil?
![Page 25: Basic design of stilts based on the CPT Julio R. Valdes Geo-Innovations Research Group Civil Engineering SDSU](https://reader036.vdocuments.net/reader036/viewer/2022062515/56649cdc5503460f949a7caa/html5/thumbnails/25.jpg)
CM y CK
materialInstalation
f1 = Ko1(’vo1) tan(’) CM CK
Needed: Ko , vo , ’ , CM , CK
CM CK
concrete
steel
drill
compactor
1.0
0.8
0.9
1.1
![Page 26: Basic design of stilts based on the CPT Julio R. Valdes Geo-Innovations Research Group Civil Engineering SDSU](https://reader036.vdocuments.net/reader036/viewer/2022062515/56649cdc5503460f949a7caa/html5/thumbnails/26.jpg)
Ko
Ko = [1 – sin(’)] OCR sin ’ Mayne & Kulhawy (1982)
Friction angle
´ = 17.6 + 11 log Kulhawy & Mayne (1990)
pa = 100 kPa ’vo = Effective stress at the center of the particle
)(avo
0.5T
pσ
q
Needed: Ko , vo , ’ , CM , CK
?
![Page 27: Basic design of stilts based on the CPT Julio R. Valdes Geo-Innovations Research Group Civil Engineering SDSU](https://reader036.vdocuments.net/reader036/viewer/2022062515/56649cdc5503460f949a7caa/html5/thumbnails/27.jpg)
OCR (fine soils)
OCR = ’p / ’vo
’p = 0.60 (qT – u2) Mayne (2005)
Needed: Ko , vo , ’ , CM , CK
OCR (coarse soils)
Mayne (2005)
OCR
0.192q T
p a
0.22
1 sin ( )( ) vo
p a
0.31
1
sin ( ) 0.27
.
![Page 28: Basic design of stilts based on the CPT Julio R. Valdes Geo-Innovations Research Group Civil Engineering SDSU](https://reader036.vdocuments.net/reader036/viewer/2022062515/56649cdc5503460f949a7caa/html5/thumbnails/28.jpg)
OCR (Fine soils)
OCR = ’p / ’vo
’p = 0.60 (qT – u2) Mayne (2005)
Needed: Ko , vo , ’ , CM , CK
OCR (Coarse soils)
Mayne (2005)
OCR
0.192q T
p a
0.22
1 sin ( )( ) vo
p a
0.31
1
sin ( ) 0.27
.
![Page 29: Basic design of stilts based on the CPT Julio R. Valdes Geo-Innovations Research Group Civil Engineering SDSU](https://reader036.vdocuments.net/reader036/viewer/2022062515/56649cdc5503460f949a7caa/html5/thumbnails/29.jpg)
Example5
12
34
6
sand
sand
sand
clay2300
20
~0
0
d = 0.7m
L = 15m
P = 4000 kN
Compacting stilts of concrete
c = 28kN/m3
![Page 30: Basic design of stilts based on the CPT Julio R. Valdes Geo-Innovations Research Group Civil Engineering SDSU](https://reader036.vdocuments.net/reader036/viewer/2022062515/56649cdc5503460f949a7caa/html5/thumbnails/30.jpg)
Example
G1=4m , =18kN/m3 , qt = 5MPa , u2 = 0kPa
=15m
sand
sand
sand
clay
G3=3m , =20kN/m3 , qt = 12MPa , u2 = 0kPa
G2=2m , =18kN/m3 , qt = 12MPa , u2 = 0kPa
G4=2.5m , =20kN/m3 , qt = 34MPa , u2 = 20kPa
G5=3.5m , =20kN/m3 , qt = 6MPa , u2 = 2300kPa
’vo=(2)(18)=36kPa
qT = qt + (1-an)u2 = 5000 + (1-0.8)(0) = 5000kPa
Needed: Ko , vo , ’ , CM , CK
o0.5
avo
0.5T .
100)(36log.
pσ
qlog.'
)(738
50001161711617
OCR = (long equation; Thick soils) = 4.29
Ko = [1 – sin(’)] OCR sin ’ = [1-sin(38.7)] (4.29)sin(38.7) = 0.93
![Page 31: Basic design of stilts based on the CPT Julio R. Valdes Geo-Innovations Research Group Civil Engineering SDSU](https://reader036.vdocuments.net/reader036/viewer/2022062515/56649cdc5503460f949a7caa/html5/thumbnails/31.jpg)
G1=4m , =18kN/m3 , qt = 5MPa , u2 = 0kPa
sand
sand
sand
clay
=15m
G3=3m , =20kN/m3 , qt = 12MPa , u2 = 0kPa
G2=2m , =18kN/m3 , qt = 12MPa , u2 = 0kPa
G4=2.5m , =20kN/m3 , qt = 34MPa , u2 = 20kPa
G5=3.5m , =20kN/m3 , qt = 6MPa , u2 = 2300kPa
’vo=(4)(18)+(2)(18)+(3)(20)+(2.5)(20)+(1.75)(20) – (9.81)(3+2.5+1.75) =182kPa
qT = qt + (1-an)u2 = 6000 + (1-0.8)(2300) = 6460 kPa
Needed: Ko , vo , ’ , CM , CK
o
.
avo
0.5T
100182log.
pσ
qlog.'
)(36
64601161711617
50
’p = 0.60 (qT – u2) = 0.60 (6460-2300) = 2496 kPa
OCR = ’p / ’vo = 2496 / 182 = 13.7
Ko = [1 – sin(’)] OCR sin ’ = [1-sin(36)] (13.7)sin(36) = 1.91
![Page 32: Basic design of stilts based on the CPT Julio R. Valdes Geo-Innovations Research Group Civil Engineering SDSU](https://reader036.vdocuments.net/reader036/viewer/2022062515/56649cdc5503460f949a7caa/html5/thumbnails/32.jpg)
G1=4m , =18kN/m3 , qt = 5MPa , u2 = 0kPa
sand
sand
sand
clay
=15m
G3=3m , =20kN/m3 , qt = 12MPa , u2 = 0kPa
G2=2m , =18kN/m3 , qt = 12MPa , u2 = 0kPa
G4=2.5m , =20kN/m3 , qt = 34MPa , u2 = 20kPa
G5=3.5m , =20kN/m3 , qt = 6MPa , u2 = 2300kPa
SUELOS
G qt u2 qT 'voEstrato Suelo (m) (Mpa) (kPa) (kPa) (kPa) OCR Ko
1 arena 4 5 0 5000 36 38.7 4.29 0.932 arena 2 12 0 12000 90 40.7 17.9 1.243 arena 3 12 0 12000 123 40 4.9 0.794 arena 2.5 34 20 34004 151 44.4 1.85 0.725 arcilla 3.5 6 2300 6460 182 36 13.7 1.91
L = 15
SoilLayer
![Page 33: Basic design of stilts based on the CPT Julio R. Valdes Geo-Innovations Research Group Civil Engineering SDSU](https://reader036.vdocuments.net/reader036/viewer/2022062515/56649cdc5503460f949a7caa/html5/thumbnails/33.jpg)
PILOTE HINCADO DE CONCRETO W = 51.45 kNd(m) = 0.7 CM = 1 CK = 1.1
CAP. FRICCIONAL CAP. DE PUNTAf As f As 'vo qp Ap qp Ap
(kPa) (m2) (kN) (kPa) (kPa) (m2) (kN)29.5 8.796 259.539
105.6 4.398 464.41389.9 6.597 593.155
117.3 5.498 645.146277.8 7.697 2138.34 199.7 10643 0.38485 4096
Qf = 4100.59 kN Qp = 4096 kN
Q = Qf + Qp - WQ = 8144.87 kN
f1 = Ko1(’vo1) tan(’) CM CK
As1 = dG1
Ap = d2/4
qp = (qT – ’vo)/k2
FS = Q / P = 8145 / 4000 = 2.04
COMPACTING STILT OF CONCRETE
FRICTIONAL CAP. TIP CAP.
![Page 34: Basic design of stilts based on the CPT Julio R. Valdes Geo-Innovations Research Group Civil Engineering SDSU](https://reader036.vdocuments.net/reader036/viewer/2022062515/56649cdc5503460f949a7caa/html5/thumbnails/34.jpg)
![Page 35: Basic design of stilts based on the CPT Julio R. Valdes Geo-Innovations Research Group Civil Engineering SDSU](https://reader036.vdocuments.net/reader036/viewer/2022062515/56649cdc5503460f949a7caa/html5/thumbnails/35.jpg)
OCR & Ko
OCR
Ko = 0.192 ( qT / pa)0.22 (´vo / pa)-0.31 OCR 0.27 (1)
Ko = [1 – sin(’)] OCR sin ’ (2)
pa = 100 kPa
(1) Mayne (1995)
(2) Mayne & Kulhawy (1982)
a) Calculate ´
b) Vary OCR until the two values of Ko (eq. 1 y 2) are similar.
![Page 36: Basic design of stilts based on the CPT Julio R. Valdes Geo-Innovations Research Group Civil Engineering SDSU](https://reader036.vdocuments.net/reader036/viewer/2022062515/56649cdc5503460f949a7caa/html5/thumbnails/36.jpg)
CPT-parameters
Dr = relative density (sands)
Dr = 100
if unknown, use OCR = 1 e = void ratio e = 1.152 – 0.233·log(qC1) + 0.043 log(OCR)
OCR305
q2.0
1C
5.0