1330
Proceedings of the 18
th
International Conference on Soil Mechanics and Geotechnical Engineering, Paris 2013
Figure 1. Soil stratigraphy of RE. Martadinata Road.
2.1 Laboratory testing
Based on plot of Atterberg limits value (liquid limit, LL, and
plastic limit, PL), moisture content, the liquidity index and
consistency index versus depth; the soil has a very soft to soft
consistency. The water content of the soil is also close to its
liquid limit.
Atterberg limits values can be used to determine the
classification of cohesive soil by plotting the values of LL and
PI on the plasticity chart based on the study of Casagrande
(1932). By plotting a value of PI and LL on a USCS plasticity
chart, the majority of dots being around A line that can be
classified as inorganic clays or inorganic silt with high plasticity
CH-MH (See Fig. 2).
CH or OH
MH or OH
"A" Line
"U" Line
ML or OL
0
10
20
30
40
50
0 10 20 30 40 50 60 70 80 90 100 110 120
Plasticity Index,
Liquid Limit, LL (%)
60
70
80
90
100
Ip (%)
BH 2
BH 3
BH 4
BH5
BH 6
BH 8
BH 9
BH 10
BH 11
BH12
BH 13
BH 14
Figure 2. USCS plasticity chart
3 STABILITY AND SETTLEMENT ANALYSIS
Stability and settlement analyses were performed at 4 zones
whereas Zone 1: Sta. 2+050 – Sta. 2+376, Zone 2: Sta. 3+275,
Zone 3: Sta. 3+400 – Sta. 3+860, and Zone 4: Sta. 3+750 and
Sta. 6+497 – Sta. 7+333. Traffic loading for long term stability
is taken as 15 kN/m
2
.
3.1 Zone 1: STA. 2+050 - STA. 2+376
Raising and stone works had been done at this zone. Potential
problems in thiz zone are stability and settlement. Analysis of
proposed design in this zone is based on the road cross-section
at approximately Sta. 2+275.
Design parameters such as the friction angle, modulus of
elasticity obtained by correlating the CPT #4 off shore and
evaluation of laboratory tests on undisturbed soil samples in
BH2 at Sta. 2+275.
The results of stability analysis of the existing road condition
indicating the road is relatively in critical condition due to FS =
1.05. Predicted magnitude of settlement was 0.36 m at the
center of the road, 0.41 m at the middle and of the road towards
to Tanjung Priok, and 0.47 m at the edge of the road towards
Tanjung Priok. The time required to reach the amount of
settlement is 6800 days.
Therefore, some proposed trial designs were analyzed to
fulfill minimum FS as follow:
3.1.1.
Corrugated prestressed concrete sheet piles
The first trial design to strengthen the road is by using
corrugated prestressed concrete sheet piles (see Table 1) to a
depth of 16m (up to silty clay soil, firm to very firm).
Table 1. Design parameters of corrugated concrete type 5
Sheet pile
type
Type
Cracking
Moment
(kN.m/m)
I
(m
4
)
A
(m
2
)
Corrugated
concrete
type 5
Elastic
269
3.5x10
-3
0.1835
To simulate the corresponding field condition i.e. water level
fluctuation, two finite element models were developed to
evaluate the infuence of the highest and lowest water level on
the road stability. The results of stability analysis indicated FS =
1.22 at the highest water level, while FS at the lowest water
level is 1.16 with large moments working on the sheet pile.
Predicted magnitude of settlement was 0.36 m at the center
of the road, 0.41 m at the middle and of the road towards to
Tanjung Priok, and 0.47 m at the edge of the road towards
Tanjung Priok. The time required to reach the amount of
settlement is 6800 days.
3.1.2 Concrete sheet pile and ground anchor
Strengthening of the road with a combination of concrete sheet
piles (see Table 1) and ground anchor. The results of the
analysis by considering the road reinforced with sheetpile (type
5) combined with additional ground anchors with an inclination
from the horizontal of 40
o
. Giving prestressed ground anchor on
presstress modeled with extreme force drawn from the total
normal stress / FK, i.e. 91.15kPa / 3 = 30.38 kN/m/m. Extreme
total normal stress obtained based on the forces acting on the
parts that have the greatest displacement. The results of the
analysis showed that the stability of the road which is reinforced
with sheetpile and supplementary reinforcement combined with
ground anchors provide FS = 1.3.
Predicted magnitude of settlement was 0.29 m at the center
of the road, 0.33 m at the middle and of the road towards to
Tanjung Priok, and 0.36 m at the edge of the road towards
Tanjung Priok. The time required to reach the amount of
settlement is 6900 days.
3.1.3 Secant pile walls
Another strengthening method is by installing secant pile walls
with diameter 0.8 m (see Table 2) to a depth of 25 m from the
surface of the existing road. The results of stability analysis
provides FS = 1.67.
