Civil Insight: A Technical Magazine Volume 2 | Page 25

CIVIL INSIGHT 2018
TEACHERS’ SECTION
25
Table 1: Geometrical confi guration of different types of piles
Types of
Model
Piles
Smaller model
steel piles
Prototype
FRP piles
FRP reinforcement
direction Modulus of
elasticity
(GPa)
0.70 na
na 2X10 9
2X10 9
1.40 na 2X10 9
Naming L
mm D t
mm d
mm D
Û
S 500 25 25 0.00
T-1 500 35 25 T-2 500 45 25 FC 1524 168.3 168.3 0.00 na 31.86
T-3 1524 170.0 198.0 0.53 0Û 33.20
T-4 1524 159.0 197.0 0.71 0Û 33.15
T-5 1524 155.0 215.0 1.13 0Û 33.15
Note: L: length of pile; D t : diameter at the pile head; d: pile tip diameter; FRP: fiber-reinforced polymer; D : angle of tapering; na: not applicable
Table 2: Index and Strength parameters of different types of soil
TO K-7 Fanshawe brick sand
(Sakr et al., 2004, 2005, 2007)
2.65 2.62 2.68
Maximum density, (g/cm ), ȡ max 1.64 1.60 1.772
Minimum density, (g/cm 3 ), ȡ min
Descriptions
Density of particles, (g/cm 3 ), ȡ s
3
1.34 1.19 1.466
3 1.58 1.52 na
3 Density at I D 60 %, (g/cm ), ȡ 60 1.52 1.43 na
Maximum void ratio, e max 0.98 1.20 0.794
Minimum void ratio, e min 0.62 0.64 0.484
Void ratio at I D 90 %, e 80 na na 0.68
Void ratio at I D 80 %, e 80 0.68 0.73 na
Void ratio at I D 60 %, e 60 0.74 0.83 na
Effective grain size, (mm), D 10 na na 0.14
Mean grain size, (mm), D 50 na na 0.26
Uniformity coefficient, U c 1.40 4.0 2.143
Coefficient of curvature, U' c 0.86 1.21 0.905
Percent fines,(%), F c 1.10 14 na
Peak stress, (deg) º, I 42.00 47.00 37.00
Critical stress state, (deg) º, I' cv (assumed) 32.00 34.00 31.00
Density at I D 80 %, (g/cm ), ȡ 80
SKIN FRICTION DETERMINATION
In this section, a method explained by Kodikara and Moore (1993) has been utilized to see the effectiveness
of the behavior.The skin friction-displacement relation can be segmented into three zones. First, as elastic
deformation when pile-ground interaction is bonded together. Second, when slip has occurred at the pile-
ground interface and ground still behaves as elastic deformation. And fi nally, when slip has occurred and
plastic zone has developed to obtain elastic perfectly plastic pile-ground interface. Figure 1 shows the pile
geometry for the skin friction determination. Assuming the small section of the pile as shown in Figure2 (a),
the stresses acting normal and parallel to the pile-ground interface respectively are shown by V n and W n as:
ɒ ୬ ൌ ɐ ୬ –ƒ൫I ୧ ൅ Ƚ൯ ൅ … ୧
(4)
The vertical and radial components of the stresses at the interface ( 0 and 0) govern this state in the form:
ɒ ଴ ൌ ɐ ଴ –ƒ൫I ୧ ൅ Ƚ൯ ൅
ୡ ౟ ୱୣୡ మ ஑
൫ଵି୲ୟ୬ ஑ ୲ୟ୬ I ౟ ൯
(5)