Landslide Analysis based on Rock Mass Classification and Kinematic Analysis in Daenaa Area, Gorontalo

Abstract

Gorontalo province crossed by a Gorontalo fault with a
movement of around 11 mm/year. The existence of this fault
zone affects the distribution and configuration of geological
structures and increases the potential for landslide in the
Gorontalo area, especially areas that crossed by Gorontalo
fault such as Daenaa. This study aims to identify rock mass
classification and using kinematics analysis to landslideprone sites in the Daenaa and surrounding areas. The
method used consists of geological observations, Scanline
Mapping, rock mass classification using Rock Mass Rating
(RMR), Slope Mass Rating (SMR), and kinematics analysis
on slopes. The results showed the slope mostly composed of
partially weathered andesite rocks. The slope discontinuities
dominated by fractures either affected by tectonic or
weathering. Scanline mapping and rock mass classification
are focused at 4 stations namely SC 1, SC 2, SC 3, and SC
4. The RMR classification results indicate the rock class
consists of 2 classes, namely Good Rock and Fair Rock.
SMR classification shows the slopes consist of stable and
partially stable. Kinematics analysis shows the failure type
is toppling failure. The results of observations indicate the
role of the geological structure in the Daenaa area is
influential in controlling landslide in the study area. Fracture
is the main factor causing landslide. The occurrence of
minor faults in the study area also decreases the stability of
the rock slope. This condition makes it necessary to take
action in the surrounding community of Daenaa area related
to mitigation of mass movement disasters.

Full text

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th
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th th
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On behalf of IAGI and the Committee, it is our pleasure to welcome all of you as delegates, presenters,
exhibitors and sponsors to this event. We believe this event would bring an enlightment including new
information/ update on the geology, new business partners, new friends, and new experiences in Lombok
island with its beautiful scenes and attractive cultures.
The Indonesian Association of Geologists (IAGI) has been existing for 60 years supporting and
involving in the development of the country. With more than 6500 members of geologists, IAGI working
in all of the geological fields including management of earth resources (oil & gas, mineral, coal,
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had 25 regional chapters (Pengurus Daerah/ Pengda), 7 sub-organisations (MGEI, ISPG, MAGI, MGTI,
MAGETI, FOSI and FGMI), and 28 Student Chapters all over Indonesian region.
This year, Lombok will host the 49th IAGI Annual Convention with hybrid event concept and Pengda
Nusa Tenggara Barat (NTB) as the main committee. The main theme will be “Geology and Sustainable
Development” that will admit our commitment as professional geologist for the achievement of
Sustainable Development Goals in Indonesia. A couple of years ago, Lombok and Sumbawa have been
distracted by a series of earthquakes that have made the people aware on geology of tectonic issues, one
of the topics that is important to be discussed in the Convention. Furthermore, Lombok which is part of
the Lesser Sunda islands, has been placed as one of the main tourism destinations in Indonesia, with a
famous UNESCO Global Geopark and Biosphere Reserve of Rinjani. The geology would really be
having important rolesin the development and management of the geopark.
For sure this event will give a place for sharing the ideas, knowledges and experiences among the
geoscientists, not only Indonesian but also for wider region of Asia. Also it would serve great opportunity
for the companies and other institutions to expose their visions and core technologies to the wide range of
participants.
Assalamu’alaikum Wr. Wb
One of the remarkable annual event held by IAGI is the Annual Scientific Convention (Pertemuan Ilmiah
Tahunan/ PIT) to be conducted in various places with a variety of theme. This event has always been used
by IAGI's members and other participants as the meeting point for sharing of new sciences, experiences,
technology development, or even for a reunion place. 600-1000 participants usually attend this Annual
Convention.
Ir. Sukmandaru Prihatmoko, M. Econ. geol.
President of IAGI
IV

Eventually, we would like to thanks to all parties who contributed and participated for the succeed of this
activity, and hopefully the 49th IAGI Annual Convention & Exhibition can be carried out smoothly as
planned.
Annual Convention & Exhibition
Chairperson of the 49th IAGI
Khatib Syarbini
As a routine event that carried out annually, the IAGI Annual Convention & Exhibition (PIT IAGI) is a
highly awaited event for all people who interested in geoscience. This annual PIT IAGI is the 49th event
that will be held in Lombok - NTB. As we are aware that, we are currently in the mid of the COVID-19
epidemic. However, as an annual event, PIT IAGI must be carried out which obviously should comply
with the procedures according to the COVID-19 standard. Therefore, the number of participants allowed
to come to the event location in Lombok is limited according to the capacity of the venue with COVID-19
standards implementation. Meanwhile, most of the participants will take part online in the PIT IAGI
event through virtual platform. All activities carried out in Lombok will be broadcasted online, hence all
participants can follow the event real time, especially for the online participants. This method is known
as the Hybrid Event which will be implemented for the 49th IAGI Annual Convention & Exhibition,
2020.
The theme of PIT IAGI 49 is "Geology and Sustainable Development" which is a main reference for the
implementation of geology science for sustainable development in various aspects such as
environmental, geo-heritage, natural resources, etc. More than 100 papers will be presented from various
geoscience disciplines. Those papers have been filtered from around 400 papers submitted to the
committee. It shows a high enthusiasm of the participants which come from various institutions such as
practitioners, government, academics and students.
The 49th IAGI Annual Convention & Exhibition will be held on 15 - 18 December 2020, at KILA
Senggigi Beach Hotel - Lombok, which will begin with a Virtual Tour on December 15th, 2020. This
event will also be combined with the environmental activities “Beach Clean Up” which will be carried
out on Friday morning, December 18th, 2020. In addition, several pre-event activities, known as “road to
PIT IAGI” have also been carried out such as: International Day for Disaster Risk Reduction (IDDR) 11-
13 October 2020, Geo-student Competition (GEOSC) 30 October - 1 November 2020, and IAGI NTB
goes to KSB (West Sumbawa Regency) which was held on 6 - 8 November 2020.
This annual event will also be merged with the National Conference of IAGI (Munas) and IAGI Election
(Pemilu) for the next period of PP IAGI Chairman. This event will obviously provide a special nuance for
the PIT IAGI activities which will be attended by most IAGI members through virtual, representatives of
Pengda and sub-organizations of IAGI.
V

PROFESSIONAL ORAL PRESENTATION
PROFESSIONAL POSTER PRESENTATION
Petroleum Engineering, Technology, and application
Geodinamic and Seismology
Natural Mineral, Coal, and Energy Resources Management
PROFESSIONAL POSTER PRESENTATION
PROFESSIONAL ORAL PRESENTATION
Petroleum Geosciences
Sedimentology and Stratigraphy
Natural Mineral, Coal, and Energy Resources Management
Petrology, Volcanology, and Geothermal
Petrology, Volcanology, and Geothermal
Petroleum Geosciences
PROFESSIONAL POSTER PRESENTATION
PROFESSIONAL ORAL PRESENTATION
Engineering Geology, and Geophysics Hidrogeology
PROFESSIONAL ORAL PRESENTATION
Petroleum Engineering, Technology, and application
PROFESSIONAL ORAL PRESENTATION
PROFESSIONAL POSTER PRESENTATION
PROFESSIONAL ORAL PRESENTATION
PROFESSIONAL POSTER PRESENTATION
Geodinamic and Seismology
PROFESSIONAL POSTER PRESENTATION
PROFESSIONAL ORAL PRESENTATION
PROFESSIONAL POSTER PRESENTATION
PROFESSIONAL ORAL PRESENTATION
Engineering Geology, and Geophysics Hidrogeology
PROFESSIONAL POSTER PRESENTATION
Marine Geology, and Oceanography
Marine Geology, and Oceanography
Sedimentology and Stratigraphy
PROFESSIONAL ORAL PRESENTATION
Environmental, and Geohazard Mitigation
Environmental, and Geohazard Mitigation
PROFESSIONAL POSTER PRESENTATION
CONTENTS
Prefaces
Topic 1
Topic 2
Topic 3
Topic 4
Topic 5
Topic 6
Topic 7
Topic 8
Topic 9
IV
1
9
41
52
93
160
4
36
114
156
166
176
The Hybrid Event:
The 49th IAGI Annual
Convention & Exhibition VI

PROFESSIONAL POSTER PRESENTATION
Unconventional and Renewable Energy
G&G Method, New Technology, and Applications
PROFESSIONAL ORAL PRESENTATION
PROFESSIONAL POSTER PRESENTATION
Geotourism and Culture Management
Geotourism and Culture Management
Unconventional and Renewable Energy
PROFESSIONAL POSTER PRESENTATION
G&G Method, New Technology, and Applications
PROFESSIONAL ORAL PRESENTATION
PROFESSIONAL ORAL PRESENTATION
Topic 10
Topic 11
Topic 12
203
272
216
271
The Hybrid Event:
The 49th IAGI Annual
Convention & Exhibition
VII

Petrology, Volcanology, and Geothermal
STUDENT ORAL PRESENTATION
STUDENT POSTER PRESENTATION
Petrology, Volcanology, and Geothermal
STUDENT ORAL PRESENTATION
STUDENT ORAL PRESENTATION
STUDENT POSTER PRESENTATION
STUDENT ORAL PRESENTATION
STUDENT POSTER PRESENTATION
Environmental, and Geohazard Mitigation
STUDENT ORAL PRESENTATION
STUDENT POSTER PRESENTATION
Sedimentology and Stratigraphy
STUDENT POSTER PRESENTATION
STUDENT POSTER PRESENTATION
STUDENT ORAL PRESENTATION
Marine Geology, and Oceanography
Engineering Geology, and Geophysics Hidrogeology
Environmental, and Geohazard Mitigation
Marine Geology, and Oceanography
STUDENT POSTER PRESENTATION
Natural Mineral, Coal, and Energy Resources Management
STUDENT ORAL PRESENTATION
Geodinamic and Seismology
STUDENT ORAL PRESENTATION
STUDENT ORAL PRESENTATION
Sedimentology and Stratigraphy
STUDENT POSTER PRESENTATION
Petroleum Geosciences
Geodinamic and Seismology
Petroleum Geosciences
Petroleum Engineering, Technology, and application
Petroleum Engineering, Technology, and application
STUDENT POSTER PRESENTATION
Engineering Geology, and Geophysics Hidrogeology
Natural Mineral, Coal, and Energy Resources Management
CONTENTS
Topic 1
Topic 2
Topic 3
Topic 4
Topic 5
Topic 6
Topic 7
Topic 8
Topic 9
287
399
434
465
469
494
312
356
393
409
443
452
459
475
The Hybrid Event:
The 49th IAGI Annual
Convention & Exhibition VIII

Geotourism and Culture Management
STUDENT ORAL PRESENTATION
STUDENT POSTER PRESENTATION
Unconventional and Renewable Energy
STUDENT ORAL PRESENTATION
Unconventional and Renewable Energy
STUDENT POSTER PRESENTATION
Geotourism and Culture Management
G&G Method, New Technology, and Applications
STUDENT ORAL PRESENTATION
G&G Method, New Technology, and Applications
STUDENT POSTER PRESENTATION
Topic 10
Topic 11
Topic 12
548
610
616
583
622
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Convention & Exhibition
IX

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THE 49TH IAGI ANNUAL CONVENTION & EXHIBITION
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Landslide Analysis based on Rock Mass Classification and Kinematic Analysis in Daenaa Area,
Gorontalo
Fauzul Chaidir A. Usman1, Muhammad Kasim1, Intan Noviantari Manyoe1
1Geological Engineering, Universitas Negeri Gorontalo
ABSTRACT
Gorontalo province crossed by a Gorontalo fault with a
movement of around 11 mm/year. The existence of this fault
zone affects the distribution and configuration of geological
structures and increases the potential for landslide in the
Gorontalo area, especially areas that crossed by Gorontalo
fault such as Daenaa. This study aims to identify rock mass
classification and using kinematics analysis to landslide-
prone sites in the Daenaa and surrounding areas. The
method used consists of geological observations, Scanline
Mapping, rock mass classification using Rock Mass Rating
(RMR), Slope Mass Rating (SMR), and kinematics analysis
on slopes. The results showed the slope mostly composed of
partially weathered andesite rocks. The slope discontinuities
dominated by fractures either affected by tectonic or
weathering. Scanline mapping and rock mass classification
are focused at 4 stations namely SC 1, SC 2, SC 3, and SC
4. The RMR classification results indicate the rock class
consists of 2 classes, namely Good Rock and Fair Rock.
SMR classification shows the slopes consist of stable and
partially stable. Kinematics analysis shows the failure type
is toppling failure. The results of observations indicate the
role of the geological structure in the Daenaa area is
influential in controlling landslide in the study area. Fracture
is the main factor causing landslide. The occurrence of
minor faults in the study area also decreases the stability of
the rock slope. This condition makes it necessary to take
action in the surrounding community of Daenaa area related
to mitigation of mass movement disasters.
INTRODUCTION
Gorontalo is crossed by a Gorontalo fault zone that moving
about 11 mm/year (Socquet et al., 2006). The existence of
this fault affects the configuration of the geological structures
along the fault zone and also increases the potential for
landslides in Gorontalo area. This condition becomes
interesting to identify the configuration of geological
structures and their effects on landslide events.
Daenaa and surrounding areas are located in the Gorontalo
fault zone. This condition makes this area vulnerable to
earthquake and landslide disasters. This area also includes
the Gorontalo Outer Ring Road (GORR) section and has
been observed several events of landslides that have occurred
along this road.
This landslide disaster has become a common problem in the
Gorontalo area. (Lihawa et al., 2014) have examined the
types and distribution of landslides in the Alo watershed
using field observations and geophysical methods. (Patuti et
al., 2017) found that the Bone Bolango area is an area that
often experiences ground movement due to morphological
characteristics of steep slopes and high weathering rates.
Research by (Usman et al., 2018) aims to determine the type
of landslide movement and the mechanism at one landslide
site of the Gorontalo Outer Ring Road (GORR) section.
This research aims to identify landslides based on Rock Mass
Rating (RMR) classification and kinematics analysis in
Daenaa, West Limboto District, Gorontalo Province. This is
done to find out the type of potential landslides that can
happen and determine the preventive options of landslide
disasters in the study area.
DATA AND METHOD
The research method is divided into field survey method for
field data collection, and quantitative analysis for data
processing and analysis. Field surveys include data
collection on slopes that prone to landslide disaster. Data
collecting consists of lithological observations, geological
structures measurements, and scanline mapping. Data
processing and analysis consists of assessing fractures
intensity on slopes, Rock Mass Rating (RMR), Slope Mass
Rating (SMR), and kinematics analysis of fractures on the
slopes.
Field data collection was carried out at 4 observation
stations with relatively steep slope conditions and have
intensive fractured outcrop. Data collection includes
describing lithology at the observation station, measurement
of the fractures on the slopes, and retrieval of slope data
using scanline mapping methods.
Data processing begins with an assessment of fracture
intensity and then classified based on the RMR
classification by (Bieniawski, 1989) to determine the rock
quality on the slope. In this research, rock strength
parameters are based on the classification of rock strength
by Selby (1993 in Saptono et al., 2013), and the RQD
parameter uses the (Palmstrom, 2005) equation as shown in
equation 1. The rating of rocks strength on the slope is
shown in table 1. RMR classification parameter shown in
table 2. =115 −3,3 ∙ ............................... (1)
Jv in equation (1) is the result of the number of fractures
divided by the scanline length. The number of fractures and
the scanline length on each slope are obtained from direct
measurements in the field using the scanline mapping
method.
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Table 1. Estimation of rock strength parameter (Selby, 1993 in Saptono et al, 2013)
Description
UCS
(MPa)
Point Load
(MPa)
Schmidt
Hammer ('R')
Rock Characteristics
Very Weak Rock - easy to cut with pocket
knife 1-25 0.04-1 10-35 Weathered weakly (Chalk, rock
salt)
Weak Rock - can be cut by pocket knife
with difficulty
25-50 1-1.5 35-40
Weakly cemented (coal,
siltstone, also schist)
Moderately Strong Rock – Shallow
indentation under a firm blow from pick
point
50-100 1.5-4 40-50 Competent sedimentary rocks
(Sandstone, shale, slate)
Strong Rock – hand-held sample breaks
with one firm blow from geological
hammer
100-200 4-10 50-60
Competent igneous and
metamorphic rocks (marble,
granite, gneiss)
Very Strong Rock – requires many blows
from geological picks to break sample > 200 > 10 > 60
Dense fine-grained igneous and
metamorphic rocks (quartzite,
dolerite, gabbro, basalt)
Table 2. Rock Mass Rating (RMR) parameters (Bieniawski, 1989)
PARAMETER RATING ASSESSMENT
Rock Strength (MPa)
> 250
100-250
50-100
25-50
5-25
1-5
<1
Rating
15 12 7 4 2 1 0
Rock-Quality Designation (%)
90-100
75-90
50-75
25-50
<25
Rating
20
17
13
8
3
Fracture Spacing (m)
> 2
0.6-2
0.2-0.6
0.06-0.2
<0.06
Rating
20
15
10
8
3
Persistence (m)
<1
1-3
3-10
10-20
> 20
Rating
6 4 2 1 0
Aperture (mm)
-
<0.1
0.1-1
1-5
> 5
Rating
6
5
4
1
0
Roughness
Very Rough
Rough
Slightly Rough
Smooth
Slickensided
Rating
6
5
3
1
0
Hard filling
Soft Filling
-
<5 mm
> 5 mm
<5 mm
> 5 mm
Rating
6
4
2
2
0
Surface weathering
Not weathered
Slightly
weathered
Weathered
medium
Weathered high Decomposed
Rating
6
5
3
1
0
Groundwater Conditions
Dry
Moist
Wet
Dripping
Flow
Rating
15
10
7
4
0
The RMR total values are then calculated using the
Romana (1985) equation to determine the Slope Mass
Rating (SMR) classes. The value of the SMR is based on the
value of the RMR by Bieniawski (1989) and the
discontinuities or fractures properties on the slope. The
equation is written as:
=−(1∙2∙3)+4 ................ (2)
Where F1 is the parallelism between the fractures
orientations and the slope face strikes, F2 is the fractures dip
angle, F3 is the relationship between the slope face to the
fracture dips, and F4 is a type of slope excavation. From the
results of SMR, slope stability will be obtained. The SMR
classification is shown in table 3.
Table 3. Slope Mass Rating (SMR) Classification (Romana, 1985)
Class
V
IV
III
II
I
SMR Value
0-20
21-40
41-60
61-80
81-100
Description
Very bad
Bad
Normal
Well
Very good
Stability
Very unstable
Unstable
Partially stable
Stable
Very stable
Potential Failure
Big planar or soil-like
circular
Planar or big
wedges
Planar along some
joint and many wedges
Some block
failure
No failure
Failure probability
0.9
0.6
0.4
0.2
0
The analysis continued with fracture kinematics
analysis on the slope to determine the type and direction of
potential landslide that can occur. Kinematics analysis is
based on the stereographic projection to determine the type
and direction of potential landslide movement that can occur
by referring to the classification of Hoek and Bray (1981 in
Wyllie and Mah, 2005). The results of data processing and
analysis are then discussed to find out the type and direction
of potential landslide that can occur to take prevention steps
to reduce the risk.
460

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THE 49TH IAGI ANNUAL CONVENTION & EXHIBITION
Lombok, December 15-18th 2020
RESULT AND DISCUSSION
The slopes that become the measurement stations consists
of 4 stations named SC 1, SC 2, SC 3, and SC 4. The slopes
are steep, the vegetation level is high, the weathering level
ranges from medium to high. Lithology of slopes is
generally composed of andesite rocks. The rocks are
characterized by dark gray to brown, porphyroaphanitic,
plagioclase as a phenocryst, inequigranular, slightly
weathered, and intensively fractured.
Scanline Mapping
Scanline mapping conducted to determine the level of
fracture intensity on the slope. Scanline mapping is done at
4 stations with a line length ranging from 5-15 meters. The
scanline mapping results show fracture intensity in SC 1 of
13/meter, SC 2 of 29/meter, SC 3 of 9/meter, and SC 4 of
26/meter.
The value of fracture intensity on the slope is one indicator
of potential landslides. High fracture intensity values can
indicate more potential landslide on the plane of the slope.
Rock Mass Rating
The Rock Mass Rating (RMR) classification is stated by
Bieniawski (1989). This classification is used to determine
the quality and characteristics of the rocks. The RMR
classification performed on 4 slopes named SC 1, SC 2, SC
3, and SC 4.
SC 1 slope is composed of andesite rocks. Rock strength in
SC 1 is included in the category of Strong Rock with
characteristics of rock samples on outcrops that can be taken
with 1 geological hammer blow. The rock strength range is
100-200 MPa. The length of the scanline in SC 1 is 9.44
meters with a total fracture of 77 measured fractures. The
RQD value on SC 1 is 89.60% and is included in the Good
Rock category.
The fracture persistence in SC 1 ranges from 3-10 meters,
the average opening is 1.59 mm, the fracture mostly
slickensided, no infill, and the fracture weathering level is
medium. The average fracture space in SC 1 is 12.2 cm or
0.122 meters. This value is included in the close spacing
category of fracture spacing. Groundwater conditions at SC
1 station are relatively dry. The observations did not show
any indication of water seepage on the slope.
Figure 1. Types of landslide failure based on kinematics analysis (Hoek and Bray,
1981 in Wyllie and Mah, 2005)
Figure 2. Scanline Mapping measurement at slopes
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The result value based on the above parameters is 64. The
total value indicates the slope of SC 1 is included in the
category of Good (II).
SC 2 slope is composed of andesite rocks. Rock strength in
SC 1 is included in the category of Strong Rock with
characteristics of rock samples on outcrops that can be taken
with 1 geological hammer blow. The rock strength range is
100-200 MPa. The length of the scanline in SC 2 is 14.24
meters with a total fracture of 148 measured fractures. The
RQD value on SC 2 is 84.01% and is included in the Good
Rock category.
The fracture persistence in SC 2 ranges from 3-10 meters,
the average opening is 2.25 mm, the fracture surface
dominantly smooth, no infill observed, and the fracture
weathering level is relatively high. The average fracture
space in SC 2 is 9.6 cm or 0.096 meters. This value is
included in the close spacing category. Groundwater
conditions at SC 2 are relatively dry. The observations did
not show any indication of water seepage on the slope.
The result of RMR based on the above parameters is 63. The
total value indicates the slope of SC 2 is included in the
category of Good (II).
SC 3 slope is composed of andesite rocks. Rock strength in
SC 3 is included in the category of Strong Rock, with the
characteristics of rock samples in outcrops that can be taken
with 1 geological hammer blow. The rock strength range is
100-200 MPa. The length of the scanline in SC 3 is 6.75
meters with a total fracture of 67 measured fractures. The
RQD value on SC 3 is 85.18% and is included in the Good
Rock category.
The fracture persistence in SC 3 ranges from 3-10 meters,
the average opening is 1.68 mm, the fracture plane is
dominant smooth, no infill observed, and the fracture
weathering level is medium. The average fracture space in
SC 3 is 10.0 cm or 0.1 meters. This value is included in the
close spacing category. Groundwater conditions at SC 3
station are relatively dry. The observations did not show any
indication of water seepage on the slope.
The result of RMR based on the above parameters is 65. The
total value indicates the slope of SC 3 is included in the
category of Good (II).
SC 4 slopes are composed of andesite rocks. Rock strength
in SC 4 is included in the Moderately Strong Rock category
with characteristics rock samples in outcrops that can be
taken using the tip of a geological hammer (pick point).
When struck with a geological hammer, the rock is
relatively crushed. The rock strength range is 50-100 MPa.
The length of the scanline stretch in SC 4 is 10.52 meters
with a total fracture of 157 measured fractures. The RQD
value on SC 4 is 72.69% and is included in the Fair Rock
category.
The fracture persistence in SC 4 ranges from 3-10 meters,
the average opening is 1.8 mm, the fracture plane
dominantly smooth, no infill observed, and the fracture
weathering level is relatively high. The average fracture
space in SC 4 is 6.7 cm or 0.067 meters. This value is
included in the close spacing category. Groundwater
conditions at SC 4 are classified as dry. The observations did
not show any indication of water seepage on the slope.
The result of RMR based on the above parameters is 54. The
total value indicates that the slope of SC 3 is included in the
Fair (III) category The rating and class results in the RMR
can determine several other characteristics of rock mass.
The rock class obtained from the RMR can be a reference
for estimating other rock engineering parameters. These
parameters such as cohesion, internal friction angle, and safe
cut slope. This is shown in table 8.
Table 4. Characteristics of rock properties based in RMR Value
No Station RMR Value Rock class
Internal Friction
Angle (o)
Cohesion
(KPa)
Safe Cut
Slope (o)
1
SC 1
64
Good (II)
35-45
300-400
65
2
SC 2
63
Good (II)
35-45
300-400
65
3
SC 3
65
Good (II)
35-45
300-400
65
4
SC 4
54
Fair (III)
25-35
200-300
55
Slope Mass Rating
SMR calculation results can show several slope conditions
measurement scanline mapping. The parameters shown
include the level of slope stability, potential landslides
failure, and failure probability. SMR classification on the
slope measurement shows the stability of the scanline
mapping slope is divided into stable and partially stable
categories. Stable categories are on the slopes SC 1 and SC
3. Partially stable categories are on the slopes SC 2 and SC
4.
Table 5. SMR Rating in the study area
Station
RMR
Value
F1 F2 F3 F4
SMR
Value
Description
Slope
Stability
Potential Failure
Failure
Probability
SC 1 64 0,15 1 -25 0 61 Good Stable Some block failure 0.2
SC 2 63 0,15 1 -25 0 59 Normal Partially
Stable
Planar along some
joints and many
wedges
0.4
SC 3 65 0,15 1 -25 0 61 Good Stable Some block failure 0.2
SC 4 54 0,15 1 -25 0 50 Normal Partially
Stable
Planar along some
joints and many
wedges
0.4
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Kinematic Analysis
Kinematics analysis is performed to determine the type and
direction of potential landslide movements. This analysis is
based on the distribution of fracture patterns to the direction
of the slope. The results of the analysis refer to the
classification of Hoek and Bray (1981).
The results of the kinematics analysis show that the
type of landslide that potentially occurs is toppling failure.
Specifically, the toppling types on the measurement slope
consist of the direct toppling and oblique toppling types.
Direct toppling was observed at SC 1 and SC 2 stations,
while oblique toppling types were observed at SC 3 and SC
4 stations.
RMR classification results indicate that the slope conditions
at the measurement station are included in the category of
strong (II), except for the slopes of SC 4 which are classified
as fair (III). SC 4 slope needs attention because the condition
of the rocks that making up the slope is relatively
unfavorable so it is susceptible to landslide movement.
According to (Singh & Goel, 2011), after knowing
the rock class, it is important to know other important factors
that can affect the stability of a slope. This includes the
influence of fractures or faults. Slopes on the fault line or
zone need attention to increase the stability of the slopes.
The SMR results show the slope is divided into
stable and fairly stable categories. The stable slope category
is observed in SC 1 and SC 3, while the partially stable slope
category observed in SC 2 and SC 4. The SC 2 location is
located in a plantation area so that it is not too dangerous for
the community and infrastructure, while SC 4 located in the
residential area. This SMR values can help determine the
preventive options to maintain the slope stability. These
preventive options are shown in table 10.
Table 6. Suggested supports for various SMR classes (Singh and Goel, 2011)
SMR Classes
SMR Values
Suggested Supports
Ia
91-100
None
Ib
81-90
None, scaling is required
IIa
71-80
(None, toe ditch, or fence), spot bolting
IIb
61-70
Toe ditch or fence nets, spot or systematic bolting
IIIa 51-60
Toe ditch and/or nets, spot or systematic bolting, spot or systematic bolting, spot
shotcrete
IIIb 41-50
(toe ditch and/or nets), systematic bolting/anchors, systematic shotcrete, toe wall and/or
dental shotcrete
IVa
31-40
Anchors, systematic shotcrete, toe wall and/or concrete (or re-excavation), drainage
IVb
21-30
Systematic reinforced shotcrete, toe wall and/or concrete, re-excavation, deep drainage
Va
11-20
Gravity or anchored wall, re-excavation
Based on the results of kinematics analysis, the
direction of potential landslide movement in the study area
is relatively northwestward following the direction of the
slope with the type of potential landslide in the form of
toppling failure.
The results of the SMR classes can be a reference
regarding the best suggested supports that can be taken. This
suggestion refers to Singh and Goel, (2011) which are
shown in table 6. The results of the SMR class in the Daenaa
area are divided into IIIa (at SC 2 and SC 4) and II b (at SC
1 and SC 3). Several supports suggestion needed in order to
stabilize the slope, especially in SC 4 that located in
residential area.
The most vulnerable slope for the landslide is the SC
4 slope. This condition is due to the rock class belonging to
the fair (III) category, classified as a partially stable slope
category, and compounded by the location of the SC 4 slope
which is on the right-lateral strike-slip fault and located in a
Figure 3. Results of slope kinematics analysis in the study area.
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residential area (figure 1). In the southwest direction of SC
4, there is a resident's house just below the slope of SC 4
(figure 5).
Figure 4. SC 4 slopes in the study area
Some suggestions for handling that can be done include
doing slope excavation to make the slopes become more
gentle or other actions that can improve slope stability based
on the suggested supports on table 6. This preventive
suggestion certainly requires consideration of slope safety
and is based on calculating the cost of proper and efficient
suggests options.
Conclusions
Based on the results of research related to soil movement in
the study area, the researchers obtained several conclusions
including:
1. The fracture intensity on the slopes in the study area is
SC 1 of 13/meter, SC 2 of 29/meter, SC 3 of 9/meter,
and SC 4 of 26/meter. High fractures intensity is found
on the slopes of SC 2 and SC 4.
2. The value of the RMR value in SC 1 is 64, SC 2 is 63,
SC 3 is 65, and SC 4 is 54. The rock class on the SC 1,
SC 2, and SC 3 slopes are included in the Good (II)
category, while SC 4 is included in the Fair (III)
category.
3. The value of SMR in SC 1 is 61, SC 2 is 59, SC 3 is 61,
and SC 4 is 50. The category of slope stability in SC 1
and SC 3 is stable, while in SC 2 and SC 4 is partially
stable.
4. Potential types of landslide movement that can occur are
direct toppling types on slopes SC 1 and SC 2, and
oblique toppling types on slopes SC 3 and SC 4. The
direction of potential landslide movement is relatively
in the southwest direction of the slope.
5. SC 4 slope is the most potential ground movement. This
is because the rock class is Fair (III), the slope is
partially stable, and located on the right-lateral strike-
slip fault in the study area.
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Acknowledgements
Researchers would like to express their appreciation and
appreciation to the Village Headchief and the community in
the Daenaa area, West Limboto District, Gorontalo
Regency, Gorontalo Province. Thank you to the Head of
Lab. JA Katili Geological Engineering that facilitated the
laboratory equipment that supports the research. Thank you
also to the geological engineering of UNG members who
have been willing to accompany the data collection so that
this research can be carried out as well as possible.
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