p–ISSN: 2723 - 6609 e-ISSN: 2745-5254
Vol. 5, No. 11, November 2024 http://jist.publikasiindonesia.id/
Indonesian Journal of Social Technology, Vol. 5, No. 11, November 2024 5210
Landslide potential is reviewed from the characteristics of the
physical properties and strong shear of the avalanche
material on the Arso-Waris National Road.
Alex Sander1*, Duha Awaluddin Kurniatullah2, Dewi Ana Rusim3, Mujiati4,
Bahtiar5
Universitas Cenderawasih, Indonesia
Email: [email protected]1*, [email protected]2,
[email protected]3, [email protected]4, [email protected]5
*Correspondence
ABSTRACT
Keywords: slope/w,
bishop, fellenius,
landslides.
There are many landslide points on the Arso-Waris National
road, so it is necessary to conduct research on the potential
for landslides from the physical and shear strength
properties. The analysis method uses Slope/W software from
GeoStudio, using the Bishop and Fellenius analysis method.
The results of the study on 4 points along the Arso-Waris
section, showed that with a decrease in the value of the shear
strength parameter, both the cohesion value (average
decrease of 69.91%) and the value of the shear angle
(average decrease of 92.77%) in the reverse analysis resulted
in a decrease in the value of the safety factor score by 71.5%
(Bishop Method) and 71.11% (Fellenius Method). The value
of the smallest (critical) safety factor is 0,498, located at
point 4 KM.105+193 in combination loading, by using
the Fellenius method. Changes in physical properties and
shear strength have the potential to reduce safety factors so
that there is potential for landslides.
Introduction
The Arso-Waris national road is one of the sections in the Trans Papua Jayapura-
Wamena segment, which is one of the government's plans to improve infrastructure in the
eastern region of Indonesia. Not only connecting Jayapura and Wamena, but this intention
is also to open the isolation of areas that have great potential to develop. The connectivity
built is expected to stimulate economic growth and expand access to education and health.
Thus it can improve the quality of life of the local community. The threat of natural
disasters and road instability is a problem that can cause damage to the road body and can
even result in the sudden disconnection of the road body, so that road performance is
reduced. The occurrence of the movement of the soil mass that makes up the slope or so-
called landslide, is a common geological phenomenon that occurs to find natural balance
(Bokko et al., 2019). Avalanches that occur on road bodies can cause discomfort for road
users and can even take lives.
Vol. 5, No. 11, November 2024 http://jist.publikasiindonesia.id/
Indonesian Journal of Social Technology, Vol. 5, No. 11, November 2024 5210
Landslide potential is reviewed from the characteristics of the
physical properties and strong shear of the avalanche
material on the Arso-Waris National Road.
Alex Sander1*, Duha Awaluddin Kurniatullah2, Dewi Ana Rusim3, Mujiati4,
Bahtiar5
Universitas Cenderawasih, Indonesia
Email: [email protected]1*, [email protected]2,
[email protected]3, [email protected]4, [email protected]5
*Correspondence
ABSTRACT
Keywords: slope/w,
bishop, fellenius,
landslides.
There are many landslide points on the Arso-Waris National
road, so it is necessary to conduct research on the potential
for landslides from the physical and shear strength
properties. The analysis method uses Slope/W software from
GeoStudio, using the Bishop and Fellenius analysis method.
The results of the study on 4 points along the Arso-Waris
section, showed that with a decrease in the value of the shear
strength parameter, both the cohesion value (average
decrease of 69.91%) and the value of the shear angle
(average decrease of 92.77%) in the reverse analysis resulted
in a decrease in the value of the safety factor score by 71.5%
(Bishop Method) and 71.11% (Fellenius Method). The value
of the smallest (critical) safety factor is 0,498, located at
point 4 KM.105+193 in combination loading, by using
the Fellenius method. Changes in physical properties and
shear strength have the potential to reduce safety factors so
that there is potential for landslides.
Introduction
The Arso-Waris national road is one of the sections in the Trans Papua Jayapura-
Wamena segment, which is one of the government's plans to improve infrastructure in the
eastern region of Indonesia. Not only connecting Jayapura and Wamena, but this intention
is also to open the isolation of areas that have great potential to develop. The connectivity
built is expected to stimulate economic growth and expand access to education and health.
Thus it can improve the quality of life of the local community. The threat of natural
disasters and road instability is a problem that can cause damage to the road body and can
even result in the sudden disconnection of the road body, so that road performance is
reduced. The occurrence of the movement of the soil mass that makes up the slope or so-
called landslide, is a common geological phenomenon that occurs to find natural balance
(Bokko et al., 2019). Avalanches that occur on road bodies can cause discomfort for road
users and can even take lives.
Landslide potential is reviewed from the characteristics of the physical properties and
strong shear of the avalanche material on the Arso-Waris National Road
Indonesian Journal of Social Technology, Vol. 5, No. 11, November 2024 5211
Based on data collected from the Jayapura National Road Implementation Center
from 2019 to 2023, it is known that the stability of the Arso-Waris national road section
increased in 2023 by 81.34%. One of the reasons why the stability has not been able to
reach 100% is that there are still several avalanche points in the form of shallow
avalanches in the embankment layer.
The Terrain shape of the Arso-Waris road section is a bumpy area ranging from
light to heavy with its relief dominated by hills to mountains. Based on the Geological
Map sheet 3413-Jayapura (Peg Cyclops) and sheet 3412-Taritatu (Keerom), issued by the
Center for Geological Research and Development, it can be known that this area is
included in the geological formations QTu (UNK formation), Tmm (Makats formation)
and Toma formation (Auwea formation). The UNK formation is in the form of Grewak
interspersed with claystone, siltstone, napalm, conglomerate sandstone, and lignite
inserts. The Makats Formation is in the form of sandstone interspersed with silt and well-
coated claystone.
The types and physical properties of the soil in each region are different because
they are influenced by climate, vegetation, geology, and morphology. Each of these
factors plays an important role in determining the type and physical properties of the soil
that can be found in an area. Soil is a natural resource that is very important for human
life, so it is important to understand how the type of soil in each region can be different.
Physical properties can be known using various testing methods, and Indonesia already
has its standard, namely the Indonesian National Standard (SNI).
Based on the above, it is necessary to conduct research related to the analysis of
slope stability on the Arso-Waris road section, through the physical properties of the soil
and the strength of the shear of the avalanche material from the slope at the research site.
Method
The location of the research is on the Arso-Waris national road, precisely in the
administrative area of Keerom Regency. Soil samples at four points of the study site were
collected for testing the physical properties and engineering of landslide potential
materials in the laboratory. The distribution of sample location points is at point 1 KM 66
+ 327, point 2 KM 80 + 725, point 3 KM 88 + 335, and point 4 KM 105 + 193.
Soil samples were collected for physical property testing and triaxial testing in the
laboratory, based on Indonesian National Standards (SNI). The soil parameters tested for
soil physical properties are in the form of moisture content (SNI 1965:2008), specific
gravity (SNI 1964:2008), content weight (SNI 03-3637-1994), grain analysis (SNI
3423:2009), Atterberg boundaries consisting of liquid limits (SNI 1967:2008), plastic
limits and soil plasticity index (SNI 1966:2008), soil shrinkage limits (SNI 3422:2008).
Meanwhile, the triaxial test for cohesive soils in an unconsolidated and non-drained state
(UU) is based on SNI 4813:2015, SNI 03-2455-2004 for soils in a consolidated state, not
drained (CU) and consolidated drained (CD). Slope stability analysis using the GeoStudio
Slope/W program version 2021.4 to obtain safety factor values.
strong shear of the avalanche material on the Arso-Waris National Road
Indonesian Journal of Social Technology, Vol. 5, No. 11, November 2024 5211
Based on data collected from the Jayapura National Road Implementation Center
from 2019 to 2023, it is known that the stability of the Arso-Waris national road section
increased in 2023 by 81.34%. One of the reasons why the stability has not been able to
reach 100% is that there are still several avalanche points in the form of shallow
avalanches in the embankment layer.
The Terrain shape of the Arso-Waris road section is a bumpy area ranging from
light to heavy with its relief dominated by hills to mountains. Based on the Geological
Map sheet 3413-Jayapura (Peg Cyclops) and sheet 3412-Taritatu (Keerom), issued by the
Center for Geological Research and Development, it can be known that this area is
included in the geological formations QTu (UNK formation), Tmm (Makats formation)
and Toma formation (Auwea formation). The UNK formation is in the form of Grewak
interspersed with claystone, siltstone, napalm, conglomerate sandstone, and lignite
inserts. The Makats Formation is in the form of sandstone interspersed with silt and well-
coated claystone.
The types and physical properties of the soil in each region are different because
they are influenced by climate, vegetation, geology, and morphology. Each of these
factors plays an important role in determining the type and physical properties of the soil
that can be found in an area. Soil is a natural resource that is very important for human
life, so it is important to understand how the type of soil in each region can be different.
Physical properties can be known using various testing methods, and Indonesia already
has its standard, namely the Indonesian National Standard (SNI).
Based on the above, it is necessary to conduct research related to the analysis of
slope stability on the Arso-Waris road section, through the physical properties of the soil
and the strength of the shear of the avalanche material from the slope at the research site.
Method
The location of the research is on the Arso-Waris national road, precisely in the
administrative area of Keerom Regency. Soil samples at four points of the study site were
collected for testing the physical properties and engineering of landslide potential
materials in the laboratory. The distribution of sample location points is at point 1 KM 66
+ 327, point 2 KM 80 + 725, point 3 KM 88 + 335, and point 4 KM 105 + 193.
Soil samples were collected for physical property testing and triaxial testing in the
laboratory, based on Indonesian National Standards (SNI). The soil parameters tested for
soil physical properties are in the form of moisture content (SNI 1965:2008), specific
gravity (SNI 1964:2008), content weight (SNI 03-3637-1994), grain analysis (SNI
3423:2009), Atterberg boundaries consisting of liquid limits (SNI 1967:2008), plastic
limits and soil plasticity index (SNI 1966:2008), soil shrinkage limits (SNI 3422:2008).
Meanwhile, the triaxial test for cohesive soils in an unconsolidated and non-drained state
(UU) is based on SNI 4813:2015, SNI 03-2455-2004 for soils in a consolidated state, not
drained (CU) and consolidated drained (CD). Slope stability analysis using the GeoStudio
Slope/W program version 2021.4 to obtain safety factor values.
Alex Sander, Duha Awaluddin Kurniatullah, Dewi Ana Rusim, Mujiati, Bahtiar
Indonesian Journal of Social Technology, Vol. 5, No. 11, November 2024 5212
Results and Discussion
Interpretation of Physical and Mechanical Properties Test Results
Table 1
Recapitulation of laboratory test results of soil physical and mechanical properties
DESCRIPTION UNIT
TEST RESULTS
DATA
PRIMER DATA SECONDS
Sample Location KM.66+327 KM.80+725 KM.80+725 KM.105+193
Sample Depth m 1.00 – 1.50 1.50 – 2.00 1.50 – 2.00 1.50 – 2.00
GRADATIONS
Gravel (%) 6.1 2.88 0.09 0.33
Pasir (%) 25.2 36.22 29.58 32.96
Lanau (%) 52.17 57.37 61.33 60.17
Lampung (%) 16.53 3.53 9.0 6.54
ATTERBERG
LIMITS
Liquid Limit (%) 19.60 18.85 22.11 24.5
Plastic Limits (%) 12.41 10.98 11.69 13.89
Plasticity Index (%) 7.20 7.87 10.42 10.61
Shrink Limit (%) 24.13 20.75 31.41 26.18
Specific Gravity Gs 2.62 2.652 2.657 2.657
Contents Weight gr/cm3 1.58 1.644 1.749 1.749
Up Air (%) 19.25 25.99 46.76 46.76
TRIAXIAL
(UU)
Kohesi kg/cm2 0.5 0.29 0.27 0.4
Sliding Angle degree 21.0 8.3 8.46 6.98
Source: Analysis results
Table 2
Recapitulation of interpretation of laboratory test results
Descriptio
n
Interpretation Results
ConclusionData
Primer Data Seconds
Sample
Location
Km.66+32
7
Km.80+72
5
Km.80+72
5
Km.105+19
3
Sample
Depth 1.00 – 1.50 1.50 – 2.00 1.50 – 2.00 1.50 – 2.00
Gradation
s Sandy Silt Sandy Silt Sandy Silt Sandy Silt Sandy Silt
Atterberg
Limits
Liquid
Limit Low Low Low Low Low
Plastic
Limits Low Low Low Low Low
Plasticity
Index Keep Keep Keep Keep Keep
Indonesian Journal of Social Technology, Vol. 5, No. 11, November 2024 5212
Results and Discussion
Interpretation of Physical and Mechanical Properties Test Results
Table 1
Recapitulation of laboratory test results of soil physical and mechanical properties
DESCRIPTION UNIT
TEST RESULTS
DATA
PRIMER DATA SECONDS
Sample Location KM.66+327 KM.80+725 KM.80+725 KM.105+193
Sample Depth m 1.00 – 1.50 1.50 – 2.00 1.50 – 2.00 1.50 – 2.00
GRADATIONS
Gravel (%) 6.1 2.88 0.09 0.33
Pasir (%) 25.2 36.22 29.58 32.96
Lanau (%) 52.17 57.37 61.33 60.17
Lampung (%) 16.53 3.53 9.0 6.54
ATTERBERG
LIMITS
Liquid Limit (%) 19.60 18.85 22.11 24.5
Plastic Limits (%) 12.41 10.98 11.69 13.89
Plasticity Index (%) 7.20 7.87 10.42 10.61
Shrink Limit (%) 24.13 20.75 31.41 26.18
Specific Gravity Gs 2.62 2.652 2.657 2.657
Contents Weight gr/cm3 1.58 1.644 1.749 1.749
Up Air (%) 19.25 25.99 46.76 46.76
TRIAXIAL
(UU)
Kohesi kg/cm2 0.5 0.29 0.27 0.4
Sliding Angle degree 21.0 8.3 8.46 6.98
Source: Analysis results
Table 2
Recapitulation of interpretation of laboratory test results
Descriptio
n
Interpretation Results
ConclusionData
Primer Data Seconds
Sample
Location
Km.66+32
7
Km.80+72
5
Km.80+72
5
Km.105+19
3
Sample
Depth 1.00 – 1.50 1.50 – 2.00 1.50 – 2.00 1.50 – 2.00
Gradation
s Sandy Silt Sandy Silt Sandy Silt Sandy Silt Sandy Silt
Atterberg
Limits
Liquid
Limit Low Low Low Low Low
Plastic
Limits Low Low Low Low Low
Plasticity
Index Keep Keep Keep Keep Keep
Landslide potential is reviewed from the characteristics of the physical properties and
strong shear of the avalanche material on the Arso-Waris National Road
Indonesian Journal of Social Technology, Vol. 5, No. 11, November 2024 5213
Shrink
Limit Tall Tall Tall Tall Tall
Specific
Gravity Keep Keep Keep Keep Keep
Contents
Weight Keep Keep Keep Keep Keep
Up Air Low Keep Tall Tall Low S/D High
Triaxial
(Uu)
Cohesion Keep Keep Keep Keep Keep
Sliding
Angle Keep Low Low Low Low to Medium
Source: Analysis results
Layout dan Cross Section
Figure 1
Layout Longsoran KM 66+327
strong shear of the avalanche material on the Arso-Waris National Road
Indonesian Journal of Social Technology, Vol. 5, No. 11, November 2024 5213
Shrink
Limit Tall Tall Tall Tall Tall
Specific
Gravity Keep Keep Keep Keep Keep
Contents
Weight Keep Keep Keep Keep Keep
Up Air Low Keep Tall Tall Low S/D High
Triaxial
(Uu)
Cohesion Keep Keep Keep Keep Keep
Sliding
Angle Keep Low Low Low Low to Medium
Source: Analysis results
Layout dan Cross Section
Figure 1
Layout Longsoran KM 66+327
Alex Sander, Duha Awaluddin Kurniatullah, Dewi Ana Rusim, Mujiati, Bahtiar
Indonesian Journal of Social Technology, Vol. 5, No. 11, November 2024 5214
Figure 2
Cross Section Longsoran KM 66+327
The avalanche at KM.66+327 is on the left side of the road towards Waris. The area
of the avalanche is 956.91 m2 with a slope of 88.14%.
Stratification of Slope Cross Sections
Based on the results of soil investigation in the form of core drills, SPT, and
laboratory test results, in each landslide location, the slope stratification is obtained as
follows:
The following is soil stratigraphic data based on the results of analysis and
correlation of field data at the KM.66+327 avalanche site.
Table 3
Soil stratigraphic data at KM.66+327
Layer N-Spt (Kn/m3) (O) C (Kpa) Classification
Layer 1 5 15.54 21 49.03 Lanau Sedang
Layer 2 20 21 30.43 60 Lanau Kaku
Layer 3 7 19 29.64 42 Medium Clay
Figure 3
The soil profile of the location of the landslide KM.66+327Lempung, sedang (Clay medium)
Lanau, kaku (Silt stiff)
Lanau, sedang (Silt medium)
106
108
110
112
114
116
-20 -18 -16 -14 -12 -10 -8 -6 -4 -2 0 2 4 6 8 10 12 14 16 18 20 22 24 26
104
102
100
98
106
108
110
112
114
116
104
102
100
98
Indonesian Journal of Social Technology, Vol. 5, No. 11, November 2024 5214
Figure 2
Cross Section Longsoran KM 66+327
The avalanche at KM.66+327 is on the left side of the road towards Waris. The area
of the avalanche is 956.91 m2 with a slope of 88.14%.
Stratification of Slope Cross Sections
Based on the results of soil investigation in the form of core drills, SPT, and
laboratory test results, in each landslide location, the slope stratification is obtained as
follows:
The following is soil stratigraphic data based on the results of analysis and
correlation of field data at the KM.66+327 avalanche site.
Table 3
Soil stratigraphic data at KM.66+327
Layer N-Spt (Kn/m3) (O) C (Kpa) Classification
Layer 1 5 15.54 21 49.03 Lanau Sedang
Layer 2 20 21 30.43 60 Lanau Kaku
Layer 3 7 19 29.64 42 Medium Clay
Figure 3
The soil profile of the location of the landslide KM.66+327Lempung, sedang (Clay medium)
Lanau, kaku (Silt stiff)
Lanau, sedang (Silt medium)
106
108
110
112
114
116
-20 -18 -16 -14 -12 -10 -8 -6 -4 -2 0 2 4 6 8 10 12 14 16 18 20 22 24 26
104
102
100
98
106
108
110
112
114
116
104
102
100
98
Landslide potential is reviewed from the characteristics of the physical properties and
strong shear of the avalanche material on the Arso-Waris National Road
Indonesian Journal of Social Technology, Vol. 5, No. 11, November 2024 5215
Modeling with Slope/W Computer Programs
Table 4
Soil parameter data used for modeling analysis at KM.66+327
Condition c (kPa) (degrees) Contents Weight
(kN/m3)
Excision 49.03 21 15.54
Back-Analysis 13 0.9 15.54
Method Bishop
1) No Burden
Figure 4
Results of Slope/W Modeling Under No Loading Conditions, with Bishop Method at
KM.66+327
In the existing analysis, the values of c=49.03 kPa and =21 were used, with the
conditions without loading as shown in Figure 4. a which depicts the slip plane with the
lowest safety number of 3.616. Meanwhile, in the reverse analysis, after the c parameter
was lowered to the value of c=13 kPa and =0.9, it showed a decrease in the value of
the safety number to 0.999 (figure 4. b). A safety figure value of 0.999 indicates that there
was a collapse (SF<1).
2) Pore Water Pressure Load (Groundwater Table)
Figure 5
Slope/W Modeling Results
a. Eksisting b. Analisis Balik
b. Analisis Balik
strong shear of the avalanche material on the Arso-Waris National Road
Indonesian Journal of Social Technology, Vol. 5, No. 11, November 2024 5215
Modeling with Slope/W Computer Programs
Table 4
Soil parameter data used for modeling analysis at KM.66+327
Condition c (kPa) (degrees) Contents Weight
(kN/m3)
Excision 49.03 21 15.54
Back-Analysis 13 0.9 15.54
Method Bishop
1) No Burden
Figure 4
Results of Slope/W Modeling Under No Loading Conditions, with Bishop Method at
KM.66+327
In the existing analysis, the values of c=49.03 kPa and =21 were used, with the
conditions without loading as shown in Figure 4. a which depicts the slip plane with the
lowest safety number of 3.616. Meanwhile, in the reverse analysis, after the c parameter
was lowered to the value of c=13 kPa and =0.9, it showed a decrease in the value of
the safety number to 0.999 (figure 4. b). A safety figure value of 0.999 indicates that there
was a collapse (SF<1).
2) Pore Water Pressure Load (Groundwater Table)
Figure 5
Slope/W Modeling Results
a. Eksisting b. Analisis Balik
b. Analisis Balik
Alex Sander, Duha Awaluddin Kurniatullah, Dewi Ana Rusim, Mujiati, Bahtiar
Indonesian Journal of Social Technology, Vol. 5, No. 11, November 2024 5216
Under the influence of MAT, with the Bishop Method at KM.66+327
In the existing analysis, the values of c=49.03 kPa and =21 were used, with the
pore water pressure loading condition as shown in Figure 5. a which depicts the slip plane
with the lowest safety number of 3.031. Meanwhile, in the reverse analysis, after the c
parameter was lowered to the value of c=13 kPa and =0.9, it showed a decrease in the
value of the safety number to 0.995 (figure 5. b). A security number value of 0.995
indicates that there has been a collapse (SF<1).
3) Traffic Load
Figure 6 Results of Slope/W Modeling in Traffic Load Conditions, with Bishop Method
at KM.66+327
In the existing analysis, the values of c=49.03 kPa and =21 were used, with the
traffic loading conditions as shown in Figure 6. a which depicts the slip field with the
lowest safety number of 3.118. Meanwhile, in the reverse analysis, after the c parameter
was lowered to the value of c=13 kPa and =0.9, it showed a decrease in the value of
the safety number to 0.824 (figure 6. b). The security number value of 0.824 indicates
that there has been a collapse (SF<1).
4) Seismic Load
Figure 7
Results of Slope/W Modeling under Seismic Load Conditions, with Bishop Method at
KM.66+327
In the existing analysis, the values of c=49.03 kPa and =21 were used, with
seismic loading conditions (earthquakes) as shown in Figure 7. a which depicts the slip
Excision
a.
Back-Analysis
b.
Indonesian Journal of Social Technology, Vol. 5, No. 11, November 2024 5216
Under the influence of MAT, with the Bishop Method at KM.66+327
In the existing analysis, the values of c=49.03 kPa and =21 were used, with the
pore water pressure loading condition as shown in Figure 5. a which depicts the slip plane
with the lowest safety number of 3.031. Meanwhile, in the reverse analysis, after the c
parameter was lowered to the value of c=13 kPa and =0.9, it showed a decrease in the
value of the safety number to 0.995 (figure 5. b). A security number value of 0.995
indicates that there has been a collapse (SF<1).
3) Traffic Load
Figure 6 Results of Slope/W Modeling in Traffic Load Conditions, with Bishop Method
at KM.66+327
In the existing analysis, the values of c=49.03 kPa and =21 were used, with the
traffic loading conditions as shown in Figure 6. a which depicts the slip field with the
lowest safety number of 3.118. Meanwhile, in the reverse analysis, after the c parameter
was lowered to the value of c=13 kPa and =0.9, it showed a decrease in the value of
the safety number to 0.824 (figure 6. b). The security number value of 0.824 indicates
that there has been a collapse (SF<1).
4) Seismic Load
Figure 7
Results of Slope/W Modeling under Seismic Load Conditions, with Bishop Method at
KM.66+327
In the existing analysis, the values of c=49.03 kPa and =21 were used, with
seismic loading conditions (earthquakes) as shown in Figure 7. a which depicts the slip
Excision
a.
Back-Analysis
b.
Landslide potential is reviewed from the characteristics of the physical properties and
strong shear of the avalanche material on the Arso-Waris National Road
Indonesian Journal of Social Technology, Vol. 5, No. 11, November 2024 5217
plane with the lowest safety number of 2.889. Meanwhile, in the reverse analysis, after
the c parameter was lowered to the value of c=13 kPa and =0.9, it showed a decrease
in the value of the safety figure to 0.744 (figure 7. b). A safety figure value of 0.744
indicates that there has been a collapse (SF<1).
5) Combination of Loading
Figure 8
Results of Slope/W Modeling under Combined Load Conditions, with Bishop Method at
KM.66+327
In the existing analysis, the values of c=49.03 kPa and =21 were used, with the
combined loading conditions as shown in Figure 8. a which depicts the sliding field with
the lowest safety number of 2.659. Meanwhile, in the reverse analysis, after the c
parameter was lowered to the value of c=13 kPa and =0.9, it showed a decrease in the
value of the safety figure to 0.628 (figure 8. b). A security number value of 0.628 indicates
that there has been a collapse (SF<1).
Recapitulation of Slope/W Modeling Results
The following is a recapitulation of the modeling results with Slope/W.
Table 5
Recapitulation of the results of 1 KM point modeling. 66+327
Loading
Conditions
Security Number (SF)
Excision Back-Analysis
Bishop Fellenius
(Ordinary) Bishop Fellenius
(Ordinary)
Unencumbered 3.616 3.407 0.999 0.998
Influence Mat 3.031 2.948 0.997 0.995
Traffic Load 3.118 2.909 0.824 0.822
Seismic 2.889 2.718 0.744 0.743
Combination 2.659 2.552 0.628 0.627
Source: Analysis results
Table 6
Recapitulation of 2 KM point modeling results. 80+725
Loading
Conditions
Security Number (SF)
Excision Back-Analysis
Bishop Fellenius
(Ordinary) Bishop Fellenius
(Ordinary)
Unencumbered 2.748 2.739 0.999 0.998
strong shear of the avalanche material on the Arso-Waris National Road
Indonesian Journal of Social Technology, Vol. 5, No. 11, November 2024 5217
plane with the lowest safety number of 2.889. Meanwhile, in the reverse analysis, after
the c parameter was lowered to the value of c=13 kPa and =0.9, it showed a decrease
in the value of the safety figure to 0.744 (figure 7. b). A safety figure value of 0.744
indicates that there has been a collapse (SF<1).
5) Combination of Loading
Figure 8
Results of Slope/W Modeling under Combined Load Conditions, with Bishop Method at
KM.66+327
In the existing analysis, the values of c=49.03 kPa and =21 were used, with the
combined loading conditions as shown in Figure 8. a which depicts the sliding field with
the lowest safety number of 2.659. Meanwhile, in the reverse analysis, after the c
parameter was lowered to the value of c=13 kPa and =0.9, it showed a decrease in the
value of the safety figure to 0.628 (figure 8. b). A security number value of 0.628 indicates
that there has been a collapse (SF<1).
Recapitulation of Slope/W Modeling Results
The following is a recapitulation of the modeling results with Slope/W.
Table 5
Recapitulation of the results of 1 KM point modeling. 66+327
Loading
Conditions
Security Number (SF)
Excision Back-Analysis
Bishop Fellenius
(Ordinary) Bishop Fellenius
(Ordinary)
Unencumbered 3.616 3.407 0.999 0.998
Influence Mat 3.031 2.948 0.997 0.995
Traffic Load 3.118 2.909 0.824 0.822
Seismic 2.889 2.718 0.744 0.743
Combination 2.659 2.552 0.628 0.627
Source: Analysis results
Table 6
Recapitulation of 2 KM point modeling results. 80+725
Loading
Conditions
Security Number (SF)
Excision Back-Analysis
Bishop Fellenius
(Ordinary) Bishop Fellenius
(Ordinary)
Unencumbered 2.748 2.739 0.999 0.998
Alex Sander, Duha Awaluddin Kurniatullah, Dewi Ana Rusim, Mujiati, Bahtiar
Indonesian Journal of Social Technology, Vol. 5, No. 11, November 2024 5218
Influence Mat 2.528 2.433 0.989 0.979
Traffic Load 2.612 2.601 0.923 0.922
Seismic 2.062 2.055 0.745 0.741
Combination 1.853 1.847 0.659 0.654
Source: Analysis results
Table 7
Recapitulation of 3 KM point modeling results. 88+335
Loading
Conditions
Security Number (SF)
Excision Back-Analysis
Bishop Fellenius
(Ordinary) Bishop Fellenius
(Ordinary)
Unencumbered 2.723 2.287 0.997 0.833
Influence Mat 2.729 2.318 0.998 0.850
Traffic Load 2.316 1.967 0.815 0.696
Seismic 1.956 1.907 0.717 0.603
Combination 1.690 1.467 0.597 0.525
Source: Analysis results
Table 8
Recapitulation of the results of modeling the 4 KM point. 105+193
Loading Conditions
Security Number (SF)
Excision Back-Analysis
Bishop Fellenius
(Ordinary) Bishop Fellenius
(Ordinary)
Unencumbered 7.345 7.315 0.984 0.980
Influence Mat 7.242 7.211 0.970 0.966
Traffic Load 5.697 5.675 0.775 0.772
Seismic 4.617 4.610 0.629 0.628
Combination 3.674 3.660 0.500 0.498
Source: Analysis results
Relationship of Safety Numbers with Sliding Strength Parameters
At avalanche point 1 at KM.66+327, the landslide occurred at a decrease in the
cohesion value from 49.03 kPa to 13 kPa or a decrease of 73.49%, while the shear angle
decreased from 21 to 0.9 or a decrease of 95.71%. The decrease in the value of the
sliding strength parameter results in a decrease in the safety figure.
At the landslide point 2 at KM. 80+725, the landslide occurred at a decrease in the
cohesion value from 28.44 kPa to 11.33 kPa or a decrease of 60.27%, while the shear
angle decreased from 8.3 to 0.7 or a decrease of 91.57%. The decrease in the value of
the sliding strength parameter results in a decrease in the safety figure. The following is
a table of security number value decreases:
Indonesian Journal of Social Technology, Vol. 5, No. 11, November 2024 5218
Influence Mat 2.528 2.433 0.989 0.979
Traffic Load 2.612 2.601 0.923 0.922
Seismic 2.062 2.055 0.745 0.741
Combination 1.853 1.847 0.659 0.654
Source: Analysis results
Table 7
Recapitulation of 3 KM point modeling results. 88+335
Loading
Conditions
Security Number (SF)
Excision Back-Analysis
Bishop Fellenius
(Ordinary) Bishop Fellenius
(Ordinary)
Unencumbered 2.723 2.287 0.997 0.833
Influence Mat 2.729 2.318 0.998 0.850
Traffic Load 2.316 1.967 0.815 0.696
Seismic 1.956 1.907 0.717 0.603
Combination 1.690 1.467 0.597 0.525
Source: Analysis results
Table 8
Recapitulation of the results of modeling the 4 KM point. 105+193
Loading Conditions
Security Number (SF)
Excision Back-Analysis
Bishop Fellenius
(Ordinary) Bishop Fellenius
(Ordinary)
Unencumbered 7.345 7.315 0.984 0.980
Influence Mat 7.242 7.211 0.970 0.966
Traffic Load 5.697 5.675 0.775 0.772
Seismic 4.617 4.610 0.629 0.628
Combination 3.674 3.660 0.500 0.498
Source: Analysis results
Relationship of Safety Numbers with Sliding Strength Parameters
At avalanche point 1 at KM.66+327, the landslide occurred at a decrease in the
cohesion value from 49.03 kPa to 13 kPa or a decrease of 73.49%, while the shear angle
decreased from 21 to 0.9 or a decrease of 95.71%. The decrease in the value of the
sliding strength parameter results in a decrease in the safety figure.
At the landslide point 2 at KM. 80+725, the landslide occurred at a decrease in the
cohesion value from 28.44 kPa to 11.33 kPa or a decrease of 60.27%, while the shear
angle decreased from 8.3 to 0.7 or a decrease of 91.57%. The decrease in the value of
the sliding strength parameter results in a decrease in the safety figure. The following is
a table of security number value decreases:
Landslide potential is reviewed from the characteristics of the physical properties and
strong shear of the avalanche material on the Arso-Waris National Road
Indonesian Journal of Social Technology, Vol. 5, No. 11, November 2024 5219
Table 9
Decrease in the value of the security number at Point 2 KM. 80+725
Source: Analysis results
At the 3rd avalanche point at KM. 88+335, the landslide occurred at a decrease in
the cohesion value from 26.48 kPa to 10.75 kPa or a decrease of 59.40%, while the shear
angle decreased from 8.46 to 0.4 or a decrease of 95.27%. The decrease in the value of
the sliding strength parameter results in a decrease in the safety figure. The following is
a table of security number value decreases:
Table 10
Decrease in the value of the security number of Point 3 KM. 88+335
Source: Analysis results
At the 4th avalanche point at KM. 105+193, the landslide occurred at a decrease in
the cohesion value from 39.23 kPa to 5.3 kPa or a decrease of 86.49%, while the shear
angle decreased from 6.98 to 0.8 or a decrease of 88.54%. The decrease in the value of
the sliding strength parameter results in a decrease in the safety figure. The following is
a table of security number value decreases:
Table 12
Decrease in the value of the security number at Point 4 KM. 105+193
Source: Analysis resultsBISHOP FELLENIUS
(ORDINARY) BISHOP FELLENIUS
(ORDINARY) BISHOP FELLENIUS
(ORDINARY)
Kondisi Tanpa Dibebani 2.748 2.739 0.999 0.998 63.65 63.56
Pengaruh MAT 2.528 2.433 0.989 0.979 60.88 59.76
Beban Lalu Lintas 2.612 2.601 0.923 0.922 64.66 64.55
Seismik 2.062 2.055 0.745 0.741 63.87 63.94
Kombinasi 1.853 1.847 0.659 0.654 64.44 64.59
KONDISI
PEMBEBANAN
ANGKA KEAMANAN (SF) PENURUNAN NILAI
ANGKA KEAMANAN (%)EKSISTING ANALISIS BALIKBISHOP FELLENIUS
(ORDINARY) BISHOP FELLENIUS
(ORDINARY) BISHOP FELLENIUS
(ORDINARY)
Kondisi Tanpa Dibebani 2.723 2.287 0.997 0.833 63.39 63.58
Pengaruh MAT 2.729 2.318 0.998 0.850 63.43 63.33
Beban Lalu Lintas 2.316 1.967 0.815 0.696 64.81 64.62
Seismik 1.956 1.907 0.717 0.603 63.34 68.38
Kombinasi 1.690 1.467 0.597 0.525 64.67 64.21
KONDISI
PEMBEBANAN
ANGKA KEAMANAN (SF) PENURUNAN NILAI
ANGKA KEAMANAN (%)EKSISTING ANALISIS BALIKBISHOP FELLENIUS
(ORDINARY) BISHOP FELLENIUS
(ORDINARY) BISHOP FELLENIUS
(ORDINARY)
Kondisi Tanpa Dibebani 7.345 7.315 0.984 0.980 86.60 86.60
Pengaruh MAT 7.242 7.211 0.970 0.966 86.61 86.60
Beban Lalu Lintas 5.697 5.675 0.775 0.772 86.40 86.40
Seismik 4.617 4.610 0.629 0.628 86.38 86.38
Kombinasi 3.674 3.660 0.500 0.498 86.39 86.39
KONDISI
PEMBEBANAN
ANGKA KEAMANAN (SF) PENURUNAN NILAI
ANGKA KEAMANAN (%)EKSISTING ANALISIS BALIK
strong shear of the avalanche material on the Arso-Waris National Road
Indonesian Journal of Social Technology, Vol. 5, No. 11, November 2024 5219
Table 9
Decrease in the value of the security number at Point 2 KM. 80+725
Source: Analysis results
At the 3rd avalanche point at KM. 88+335, the landslide occurred at a decrease in
the cohesion value from 26.48 kPa to 10.75 kPa or a decrease of 59.40%, while the shear
angle decreased from 8.46 to 0.4 or a decrease of 95.27%. The decrease in the value of
the sliding strength parameter results in a decrease in the safety figure. The following is
a table of security number value decreases:
Table 10
Decrease in the value of the security number of Point 3 KM. 88+335
Source: Analysis results
At the 4th avalanche point at KM. 105+193, the landslide occurred at a decrease in
the cohesion value from 39.23 kPa to 5.3 kPa or a decrease of 86.49%, while the shear
angle decreased from 6.98 to 0.8 or a decrease of 88.54%. The decrease in the value of
the sliding strength parameter results in a decrease in the safety figure. The following is
a table of security number value decreases:
Table 12
Decrease in the value of the security number at Point 4 KM. 105+193
Source: Analysis resultsBISHOP FELLENIUS
(ORDINARY) BISHOP FELLENIUS
(ORDINARY) BISHOP FELLENIUS
(ORDINARY)
Kondisi Tanpa Dibebani 2.748 2.739 0.999 0.998 63.65 63.56
Pengaruh MAT 2.528 2.433 0.989 0.979 60.88 59.76
Beban Lalu Lintas 2.612 2.601 0.923 0.922 64.66 64.55
Seismik 2.062 2.055 0.745 0.741 63.87 63.94
Kombinasi 1.853 1.847 0.659 0.654 64.44 64.59
KONDISI
PEMBEBANAN
ANGKA KEAMANAN (SF) PENURUNAN NILAI
ANGKA KEAMANAN (%)EKSISTING ANALISIS BALIKBISHOP FELLENIUS
(ORDINARY) BISHOP FELLENIUS
(ORDINARY) BISHOP FELLENIUS
(ORDINARY)
Kondisi Tanpa Dibebani 2.723 2.287 0.997 0.833 63.39 63.58
Pengaruh MAT 2.729 2.318 0.998 0.850 63.43 63.33
Beban Lalu Lintas 2.316 1.967 0.815 0.696 64.81 64.62
Seismik 1.956 1.907 0.717 0.603 63.34 68.38
Kombinasi 1.690 1.467 0.597 0.525 64.67 64.21
KONDISI
PEMBEBANAN
ANGKA KEAMANAN (SF) PENURUNAN NILAI
ANGKA KEAMANAN (%)EKSISTING ANALISIS BALIKBISHOP FELLENIUS
(ORDINARY) BISHOP FELLENIUS
(ORDINARY) BISHOP FELLENIUS
(ORDINARY)
Kondisi Tanpa Dibebani 7.345 7.315 0.984 0.980 86.60 86.60
Pengaruh MAT 7.242 7.211 0.970 0.966 86.61 86.60
Beban Lalu Lintas 5.697 5.675 0.775 0.772 86.40 86.40
Seismik 4.617 4.610 0.629 0.628 86.38 86.38
Kombinasi 3.674 3.660 0.500 0.498 86.39 86.39
KONDISI
PEMBEBANAN
ANGKA KEAMANAN (SF) PENURUNAN NILAI
ANGKA KEAMANAN (%)EKSISTING ANALISIS BALIK
Alex Sander, Duha Awaluddin Kurniatullah, Dewi Ana Rusim, Mujiati, Bahtiar
Indonesian Journal of Social Technology, Vol. 5, No. 11, November 2024 5220
One thing about the results of the analysis using the Bishop and Fellenius method
is that the value of Bishop's security number is always greater than that of Fellenius. This
is due to a difference in approach to calculating the interaction of forces on the soil.
Bishop's method considers the normal force and shear force between each slice, providing
a more comprehensive and accurate picture of the slope's stability. On the other hand, the
Fellenius Method does not take into account the interaction of forces between slices,
which results in a more conservative estimation. In addition, Bishop used the balance of
moment and force in his calculations, while Fellenius only used the balance of forces.
Bishop's more detailed approach results in more accurate and usually higher results.
The higher the safety score, the farther the slope is from the possibility of landslides.
The lower the safety score, the greater the possibility of landslides.
Conclusion
After connecting various parameters and conducting a series of analyses, the
following conclusions were obtained. Based on the results of drilling, N-SPT values,
laboratory testing, and the USCS classification system on samples from a depth of 1 to 2
meters, the characteristics of the physical properties of the avalanche material on the
Arso-Waris road section are known. The soil along this section, according to the USCS
classification, is included in the category of silt with low plasticity or Mud-Low Plasticity
(ML). The liquid limit and plastic limit of the soil are at a low level, while the shrinkage
limit is high. This low plasticity property is indicated by a moderate plasticity index value,
but the soil has a considerable tendency to change volume, which is indicated by a high
shrinkage limit value. Its plasticity index is medium, while the moisture content varies
from low to high.
In addition, it was found that the relationship between the safety number and the
shear strength showed that when the shear strength parameters (c and φ) decreased, the
safety number also decreased, thus increasing the potential for landslides. The value of
the smallest or most critical safety figure was found to be 0.498 at point 4 KM.105+193
under the combined loading condition, which was obtained through the Fellenius method.
Indonesian Journal of Social Technology, Vol. 5, No. 11, November 2024 5220
One thing about the results of the analysis using the Bishop and Fellenius method
is that the value of Bishop's security number is always greater than that of Fellenius. This
is due to a difference in approach to calculating the interaction of forces on the soil.
Bishop's method considers the normal force and shear force between each slice, providing
a more comprehensive and accurate picture of the slope's stability. On the other hand, the
Fellenius Method does not take into account the interaction of forces between slices,
which results in a more conservative estimation. In addition, Bishop used the balance of
moment and force in his calculations, while Fellenius only used the balance of forces.
Bishop's more detailed approach results in more accurate and usually higher results.
The higher the safety score, the farther the slope is from the possibility of landslides.
The lower the safety score, the greater the possibility of landslides.
Conclusion
After connecting various parameters and conducting a series of analyses, the
following conclusions were obtained. Based on the results of drilling, N-SPT values,
laboratory testing, and the USCS classification system on samples from a depth of 1 to 2
meters, the characteristics of the physical properties of the avalanche material on the
Arso-Waris road section are known. The soil along this section, according to the USCS
classification, is included in the category of silt with low plasticity or Mud-Low Plasticity
(ML). The liquid limit and plastic limit of the soil are at a low level, while the shrinkage
limit is high. This low plasticity property is indicated by a moderate plasticity index value,
but the soil has a considerable tendency to change volume, which is indicated by a high
shrinkage limit value. Its plasticity index is medium, while the moisture content varies
from low to high.
In addition, it was found that the relationship between the safety number and the
shear strength showed that when the shear strength parameters (c and φ) decreased, the
safety number also decreased, thus increasing the potential for landslides. The value of
the smallest or most critical safety figure was found to be 0.498 at point 4 KM.105+193
under the combined loading condition, which was obtained through the Fellenius method.
Landslide potential is reviewed from the characteristics of the physical properties and
strong shear of the avalanche material on the Arso-Waris National Road
Indonesian Journal of Social Technology, Vol. 5, No. 11, November 2024 5221
Bibliography
Agustina D.A.& Elfrida, 2019, Pengaruh Perubahan Kadar Air Terhadap Kekuatan
Geser Tanah Lempung, Sigma Teknika, Vol.2,No.1 115-122.
Armayani, A., 2012, Studi Sifat fisis Batuan Pada Daerah Rawan Longsor Kecamatan
Parangloe Kabupaten Gowa Sulawesi selatan, Jurusan Fisika FMIPA, Universitas
Islam Negeri Alauddin, Makasar.
A. Chandra, H. Wayangkau, & R. Horik, 2021, Analisa Kestabilan Lereng Pada Lokasi
Perumnas IV Padang Bulan Kota Jayapura Dengan Metode Limit Equilibrium
(Bishop Disederhanakan), Universitas Cenderawasih.
Badan Standarisasi Nasional, SNI 8460:2017, Persyaratan Perancangan Geoteknik
Bidyashwari H., dkk, 2017, Physical Properties of Soil and Its Implication to Slope
Stability of Nungbi Khunou, NH-150, Manipur, International Journal of
Geosciences, 8:1332-1343
Bokko J., dkk, 2019, Analisis Kelongsoran Jalan Poros Sangalla-Batualu dengan
Program Plaxis, Dynamic Saint Jilid IV, No.1.
Das, Braja M., 1995, Mekanika Tanah (Prinsip-Prinsip Rekayasa Geoteknis) Jilid 1,
Gadjah Mada University Press, Surabaya.
D A Kurniatullah et al, 2020, Bearing capacity of synthetic granular column enchased
reinforcement geogrid on soft soil, Department of Civil Engineering, Faculty of
Engineering, Universitas Hasanuddin, Makassar, Indonesia.
Direktorat Jenderal Bina Marga, Buku Petunjuk Teknis Perencanaan Penanganan
Longsoran.
Hakim R.N., dkk, 2020, Studi Pengaruh Kadar Air Terhadap Kuat Geser Tanah Pada
Area Bekas Tambang di Kota Banjarbaru, Jurnal Geosapta Vol.6 No.1
Hardiyatmo, H.C., 2002, Mekanika Tanah I Edisi ke-3, Yogyakarta: Gadjah Mada
University Press
Hardiyatmo, H.C., 2003, Mekanika Tanah II Edisi ke-3, Gadjah Mada University Press,
Yogyakarta.
Kristie, H.J. & Budiman, A., 2021, Karakteristik Sifat Fisis Tanah Daerah Potensi
Longsor di Jalan Raya Sumbar Riau Nagari Koto Alam, Sumatera Barat.
strong shear of the avalanche material on the Arso-Waris National Road
Indonesian Journal of Social Technology, Vol. 5, No. 11, November 2024 5221
Bibliography
Agustina D.A.& Elfrida, 2019, Pengaruh Perubahan Kadar Air Terhadap Kekuatan
Geser Tanah Lempung, Sigma Teknika, Vol.2,No.1 115-122.
Armayani, A., 2012, Studi Sifat fisis Batuan Pada Daerah Rawan Longsor Kecamatan
Parangloe Kabupaten Gowa Sulawesi selatan, Jurusan Fisika FMIPA, Universitas
Islam Negeri Alauddin, Makasar.
A. Chandra, H. Wayangkau, & R. Horik, 2021, Analisa Kestabilan Lereng Pada Lokasi
Perumnas IV Padang Bulan Kota Jayapura Dengan Metode Limit Equilibrium
(Bishop Disederhanakan), Universitas Cenderawasih.
Badan Standarisasi Nasional, SNI 8460:2017, Persyaratan Perancangan Geoteknik
Bidyashwari H., dkk, 2017, Physical Properties of Soil and Its Implication to Slope
Stability of Nungbi Khunou, NH-150, Manipur, International Journal of
Geosciences, 8:1332-1343
Bokko J., dkk, 2019, Analisis Kelongsoran Jalan Poros Sangalla-Batualu dengan
Program Plaxis, Dynamic Saint Jilid IV, No.1.
Das, Braja M., 1995, Mekanika Tanah (Prinsip-Prinsip Rekayasa Geoteknis) Jilid 1,
Gadjah Mada University Press, Surabaya.
D A Kurniatullah et al, 2020, Bearing capacity of synthetic granular column enchased
reinforcement geogrid on soft soil, Department of Civil Engineering, Faculty of
Engineering, Universitas Hasanuddin, Makassar, Indonesia.
Direktorat Jenderal Bina Marga, Buku Petunjuk Teknis Perencanaan Penanganan
Longsoran.
Hakim R.N., dkk, 2020, Studi Pengaruh Kadar Air Terhadap Kuat Geser Tanah Pada
Area Bekas Tambang di Kota Banjarbaru, Jurnal Geosapta Vol.6 No.1
Hardiyatmo, H.C., 2002, Mekanika Tanah I Edisi ke-3, Yogyakarta: Gadjah Mada
University Press
Hardiyatmo, H.C., 2003, Mekanika Tanah II Edisi ke-3, Gadjah Mada University Press,
Yogyakarta.
Kristie, H.J. & Budiman, A., 2021, Karakteristik Sifat Fisis Tanah Daerah Potensi
Longsor di Jalan Raya Sumbar Riau Nagari Koto Alam, Sumatera Barat.