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The Engineering Characteristics and Classifications of Rock Masses along Road Section from Prambanan to Patuk, Yogyakarta, Indonesia Aisyah Shahirah Juhari; I Gde Budi Indrawan, Dr.; Wahyu Wilopo
Journal of Applied Geology Vol 6, No 2 (2021)
Publisher : Geological Engineering Department Universitas Gadjah Mada

Show Abstract | Download Original | Original Source | Check in Google Scholar | Full PDF (4973.159 KB) | DOI: 10.22146/jag.58034

Abstract

Several attraction places and agriculture area that essentials for tourism and villager to do their activities are located approximately 6 km along the road of Candi Ijo to Ngoro-Oro in between Prambanan and Patuk sub-districts, Yogyakarta, Indonesia. Many jointed rock masses along the road have the potential to fail. This paper describes the rock mass characteristic and quality determined using the Geological Strength Index (GSI) and Rock Mass Rating (RMR) classifications. The rock mass characteristic and quality were essentially the preliminary results of a study to evaluate stability of the rock slopes along the road of Candi Ijo to Ngoro-Oro. Field observation and laboratory tests were carried out to determine parameters of the GSI and RMR.  The results show that the slopes in the study area consisted of tuffaceous sandstone, vitric tuff, lithic tuff, cemented tuffaceous sandstone, lapilli tuff, subarkose, laminated mudrock, and laminated tuffaceous sandstone. The intact rocks were classified as weak to very strong. The research area consisted of three rock mass qualities, namely fair rock mass quality having GSI between 30 and 45 and RMR between 41 and 60,  good rock mass quality having GSI between 46 to 65 and RMR between 61 and 80, and very good rock mass quality having GSI > 65 and RMR between 81-100. The relationship between GSI and RMR obtained in this study was in good agreement with that proposed by Hoek et al. (1995).
Estimating of Maximum Groundwater Level to Trigger Landslide in Batu Hijau Open Pit Mine, West Nusa Tenggara, Indonesia Amirul Aiman Abd Karim; Wahyu Wilopo; I Gde Budi Indrawan; Yan Adriansyah
Journal of Applied Geology Vol 5, No 2 (2020)
Publisher : Geological Engineering Department Universitas Gadjah Mada

Show Abstract | Download Original | Original Source | Check in Google Scholar | Full PDF (1930.019 KB) | DOI: 10.22146/jag.58135

Abstract

The safety of the employees is essential in the mining activity area. Thus, the sloping wall of the pit needs to evaluate from time to time to avoid any loss due to landslide. One of the essential parameters to lead to slope failure is groundwater. Therefore, this paper highlights the limitations of the groundwater for the existing slope mine by analyzing it for several groundwater levels until it reached a safety factor below 1.2. The analysis was done using a finite element method for slope stability and finite element analysis for groundwater seepage for groundwater modeling. The results show that the safety factor of the slope showing a linearly decreasing trend and safety factor reached below 1.2 when 70 m increment in groundwater level from the original groundwater level model.
Comparison of Coal Reserve Estimation Methods, Case Study PT. Bukit Asam Area, South Sumatra, Indonesia Taufiq Muhammad Wijayanto; Wahyu Wilopo; I Gde Budi Indrawan; Sunarko Sunarko
Journal of Applied Geology Vol 6, No 1 (2021)
Publisher : Geological Engineering Department Universitas Gadjah Mada

Show Abstract | Download Original | Original Source | Check in Google Scholar | Full PDF (1884.041 KB) | DOI: 10.22146/jag.58366

Abstract

The calculation of coal reserves is influenced by the dimensions or size of the coal deposit. There are several types of coal reserve calculation methods, and the use of these methods is adjusted to existing geological conditions. Each method will produce a different amount of coal reserves, although the location is the same. Besides, the amount of coal mining that can be produced is primarily determined by the mine design, especially the optimal slope as a basis for mining pits in the coal extraction. This research aims to estimate coal reserves based on existing pit designs using a variety of methods. Data on coal thickness and topography are used as the basis for reserves estimation. Coal reserve estimation is conducted in several methods: nearest neighbor point (NNP), inverse distance weighted (IDW), and kriging using Surfer 13 software. The results of the reserves estimation indicate that kriging is the best method by providing the smallest error value with an RMSE value of 0.67 and coal reserves of 27,801,543 tons.
Assessment of groundwater leakage source using hydrochemical data and isotopes in the Pandanduri dam tunnel, Lombok Island, Indonesia Heru Hendrayana; Doni Prakasa Eka Putra; Hendy Setiawan; I Gde Budi Indrawan; Wawan Budianta; Wahyu Wilopo
Journal of Degraded and Mining Lands Management Vol 10, No 1 (2022)
Publisher : Brawijaya University

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.15243/jdmlm.2022.101.3961

Abstract

Leakage or seepage in reservoirs and dams has the potential for structural instabilities persuaded by water leakage pathways and linked to economic consequences. An environmental isotopic and hydrochemical research was conducted to determine the source and origin of seepages on the tunnel of Pandanduri dam, Lombok Island, Indonesia. This study aimed to examine the source of the tunnel leak on the dam site and the origin or source of water at the point of leakage based on water chemistry data and stable isotopes. To identify the source of the leakage water in the tunnel dam, 33 samples of the leakage water, groundwater, reservoir water, river water, and rainfall water were taken for chemical and isotopic composition analysis. The field measured the reservoir level, spring discharges, and physicochemical parameters (EC, pH, TDS, TSS). The physicochemical parameters show that the leakages water is similar to reservoir water. The types of leakage water in the tunnel belong to alkaline water, predominantly sulfate-chloride. This type of water is deep groundwater with a higher sulfate and chloride concentration than surface water or shallow groundwater. Hydrochemical and isotope analysis showed that water origin at leakage points is dominated by groundwater.
Engineering Geology of Diversion Tunnel Area at the Meninting Dam Construction, West Lombok, Province of West Nusa Tenggara, Indonesia Yunie Wiyasri; Anastasia Dewi Titisari; Sia Pamela Dita; I Gde Budi Indrawan
Journal of Applied Geology Vol 7, No 1 (2022)
Publisher : Geological Engineering Department Universitas Gadjah Mada

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.22146/jag.57293

Abstract

The construction of Meninting Dam is undertaken to resolve the water needs in Meninting Watershed, West Lombok, Province of West Nusa Tenggara, Indonesia. Therefore, creating a diversion tunnel is imperative to avert the river flow as the dam project commences. Also, engineering geology work on the soil and rocks, including the classification of physical and mechanical properties were conducted in the intended tunnel site. These considerations were necessary because of the unavailability of rock identification data using the GSI (Geological Strength Index) method which used to design the portal slopes as a significant factor in tunnel safety. The results show the proposed area for diversion tunnel construction to be in the lithology of the polymict breccia and the lapilli tuff units, and the soil conditions were included in the SM category (silty sand). The level of surface rock weathering was divided into 3 units, including: highly weathered residual soil lapilli tuff, and highly, as well as moderately weathered polymict breccias. Meanwhile, 4 units were identified on the rock cores (subsurface) comprising highly weathered residual soil of lapilli tuff, and highly, moderately, and slightly weathered polymict breccias. Based on GSI (Geological Strength Index) of rock and surface data from the area of study, the rock quality was grouped as poor (GSI values: 21-40) to very poor (GSI values: 0-20). However, drilling data classified the mass quality subsurface rocks in fair (GSI values 41-55), poor (GSI values: 21-40), particularly in tunnels, and very poor (GSI values 0-20). Therefore, the rock mass quality is possibly used to design the slope of the tunnel portal as 45⁰-55⁰, in order to ensure safety.
Stability Evaluation of Diversion Tunnel Portal Slopes at Lau Simeme Dam Site, Indonesia, using Limit Equilibrium Method Nurul Huda; I Gde Budi Indrawan; Wahyu Wilopo
Journal of Applied Geology Vol 7, No 1 (2022)
Publisher : Geological Engineering Department Universitas Gadjah Mada

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.22146/jag.58069

Abstract

Construction of the Lau Simeme Dam used a tunnel as a diversion channel. Slopes at the diversion tunnel portals were prone to failure due to the tunnel excavation and earthquake. Earthquake load was not considered in the designs of the inlet and outlet portal slopes. This research evaluated stability of the tunnel portal slopes under static and earthquake loads using limit equilibrium methods of the Bishop Simplified and Morgenstern-Price. Input material properties for the slope stability analyses were obtained from evaluations of soil and rock cores, including determination of lithology type and rock mass quality based on Geology Strength Index (GSI), and laboratory testing. Evaluations of soil and rock cores indicated that the inlet portal slope consisted of residual soil, good quality tuff breccia, and good quality sandstone. The outlet portal slope consisted of residual soil, poor quality sandstone, poor quality tuff breccia, fair quality sandstone, fair quality tuff breccia, and good quality tuff breccia. The earthquake load coefficient determined by the seismic analyses based on the peak ground acceleration map for 10% probability exceedance in 50 year was 0.125 g. The slope stability analyses showed that the designed inlet and outlet portal slopes were stable under static and earthquake loads. The Bishop Simplified and Morgenstern-Price resulted in relatively similar Fs values. The Fs values of the inlet and outlet portal slopes decreased with the earthquake load application. Although Fs values of the outlet slope under static and earthquake loads met the requirements specified by SNI 8460:2017, the rock mass conditions, particularly the poor rock masses of layers 2 and 3, required special attention. Application of slope reinforcement methods, such as shotcrete, is suggested to further increase the slope stability.
Numerical Analyses of Tunnel Outlet Slope at Leuwikeris Dam, West Java, Indonesia Sunardi Sunardi; I Gde Budi Indrawan; Ardian Baroto Murti
Journal of Applied Geology Vol 7, No 1 (2022)
Publisher : Geological Engineering Department Universitas Gadjah Mada

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.22146/jag.69701

Abstract

The excavated slope of the diversion tunnel outlet at the Leuwikeris Dam was designed based on core test data and the Circular Failure Chart (CFC) method. Stability of the excavated slope under static and seismic loads has not been verified using a different method. The objective of this research was to evaluate performance of the excavated slope under static and seismic loads using the finite element method (FEM).  Stability analyses of the natural slope were also carried out to assess the improved stability of the slope after excavation. Geological mapping, examinations of drill cores and borehole logs, and laboratory tests were conducted to characterise the soils and rocks comprising the tunnel outlet slope. The rock masses were characterised using the Geological Strength Index (GSI) for the input parameters of the Generalised Hoek-Brown criterion. The slope stability analyses under static and seismic loads were performed using the finite element-based computer package RS2. The results show that the diversion tunnel construction site consists of residual soil and very poor to fair quality andesite breccia rock and tuff breccia with thin claystone intercalation. The groundwater table was located approximately 40 m below the ground surface. In general, the seismic load reduced stability of the slopes. The critical strength reduction factor (SRF) values of the natural portal slope, which had 40º inclination, were 3.6 and 1.45 under static and seimic loads, respectively. Meanwhile, the SRF values of the excavated slope, which had seven benches and 55 to 74º inclinations, were 3.83 and 1.78 under static and seismic loads, respectively. The natural and excavated slopes were considered stable under static and seismic loads and met the stability criteria specified by the National Standardization Agency (2017). The slope design increased the slope FS values by 6% and 20% under static and seismic loads, respectively.
Stability Analysis of Cut Slope Using RMR and SMR Tri Puji Astuti; I Gde Budi Indrawan; Didit Hadi Barianto
Applied Research on Civil Engineering and Environment (ARCEE) Vol. 3 No. 03 (2022): Resilience in Construction
Publisher : POLITEKNIK NEGERI JAKARTA

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.32722/arcee.v3i03.4783

Abstract

The Planjan - Tepus road is built on a slightly steep karst morphology, necessitating slope excavation works. Slope stability is one of the elements to consider, particularly in slope excavation work. The excavation depth of the slopes sampled in this research is up to 48 meters. It is critical to undertake slope stability analysis quickly, precisely, and safely. For rapidly examining slopes, empirical approaches such as Rock Mass Rating (RMR) and Slope Mass Rating (SMR) can be utilized. An examination of the limit equilibrium method was performed using Rocscience Slide v.6.0 software to assure the slope stability level further. The limit equilibrium method used is Morgenstern-Price and Spencer. The value of slope stability analysis using the RMR method is 41-53, and the rock mass quality is categorized as class III (fair). The value of slope stability analysis using the SMR method 41-53, the rock mass quality is categorized as class III (normal), with slope stability in partially stable conditions. Slope stability using the limit equilibrium method produces a safety factor value of 1.670 - 1.680 for conditions without seismic loads and 1.137 - 1.154 for conditions with seismic loads. According to the findings of this analysis, the slope is in stable (safe) conditions.
Slope Stability Analysis Using Finite Element Method on Tepus-Jerukwudel Road Dian Rusmanawati; I Gde Budi Indrawan; Hendy Setiawan
Applied Research on Civil Engineering and Environment (ARCEE) Vol. 3 No. 03 (2022): Resilience in Construction
Publisher : POLITEKNIK NEGERI JAKARTA

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.32722/arcee.v3i03.4801

Abstract

Tepus-Jerukwudel Road construction is one of the South Coast Java Road sections located in Gunungkidul Regency, Special Region of Yogyakarta. One of the hills with the deepest excavation depth is at STA 14+350. The research location includes the Punung Formation which is dominated by reef limestones. The existing rock lithology is floatstone. The depth of the road excavation is more than 20 meters. The slope design is 3V:1H. This research aimed to analyze the slope stability of the Tepus-Jerukwudel Road and assess the safety factor of the slope design. We used the finite element method (FEM) in the Rocscience Phase2 v8.0 software by applying the Generalized Hoek-Brown method for the rock failure criteria. The loads considered in the slope stability analysis were live loads, dead loads, surcharge loads, and seismic loads. The results of the slope analysis without seismic loads resulted in the safety factor values for the left and right slopes of 4,49 and 3,32, respectively. For seismic loads conditions, the safety factor values for the left and right slopes are 3,74 and 2,66. The results indicated that slope design of the road is in a stable condition in accordance with the estimated static and seismic loads.
Engineering Geology and Slope Stability of West Pit Coal Mine of PT. Tawabu Mineral Resource, East Kalimantan, Indonesia Rama Tri Saksono; I Gde Budi Indrawan; Wahyu Wilopo
Journal of Applied Geology Vol 7, No 2 (2022)
Publisher : Geological Engineering Department Universitas Gadjah Mada

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.22146/jag.76532

Abstract

The research area was located in the west pit of the open pit coal mine of PT. Tawabu Mineral Resource (TMR) which is located in Bengalon District, East Kutai Regency, East Kalimantan Province, Indonesia. The research was driven by several landslides that occurred in the research area, but the engineering geological conditions and stability of the remaining slopes have not been evaluated. The objectives of this study were to better understand the engineering geological conditions and stability of the research area. The engineering geological conditions (i.e., geomorphology, rock and soil, geological structure, and groundwater conditions) were evaluated by photogrametric analyses, field observations, and analyses of borehole logs and laboratory test results. The slope stability analyses were firstly carried out by conducting back stability analyses of failed slope on the northern lowwall slope segment. The shear strength parameters obtained from the back analyses were then used for forward stability analyses of the remaining 10 lowwall and highwall slopes. The slope stability analyses involved deterministic and probabilistic analyses, under static and dynamic using the limit equilibrium method (LEM).  The results showed that the research area and the surrounding consisted of two geomorphological units, namely the alluvial plain and structural hills. Rocks in the study area consisted of claystone, sandstone, and coal with a general layer strike direction of N59°E – N63°E with a dip of 19°-26°. These rocks were grouped into two lithological units, namely the alternating of claystone and sandstone unit and alternating of sandstone and claystone unit. The geological structures were identified on the highwall, from west to east namely major sinistral shear fault with a relative direction of NNE-SSW, two minor sinistral shear faults with a relative direction of NE-SW, and a major dextral shear fault with a relative direction of NW-SE. These geological structures were interpreted as being formed by the folding process. The groundwater level was estimated at a level of -45 m to 20 m. The slope stability analyses showed that only the East HW-4 slope, which was located on the east highwall, was unstable. It is recommended to optimize the slope by either lowering the groundwater elevation by 4 m from the actual level or by reducing the angle the overall slope to 31°.
Co-Authors Abd Karim, Amirul Aiman Abrar, Mifthahul Adriansyah, Yan Afandi, Valentino Ilham Aisyah Shahirah Juhari Alfrianto, Rifki Alvian Rizky Yanuardian Amirul Aiman Abd Karim Anastasia Dewi Titisari Aprilia, Faridha Ardian Baroto Murti Aung, Hnin Thazin Baniarga Prabowo Daniel Happy Putra Daru Jaka Sasangka Dian Insani Dian Rusmanawati Didit Hadi Barianto Diyan Aditya Putra Pratama Diyaning Ratri Doni Prakasa Eka Putra Dwi Agus Kuncoro Dwikorita Karnawati Fahmi Aldiamar Fahmi Aldiamar, Fahmi Faridha Aprilia Fathan Hanifi Mada Mahendra Fatkhiandari, Irien Akinina Febrie Maulana Fajrin Gevor, Even Gusti Imam Warman Hendy Setiawan Heru Hendrayana Hitznaiti Zaidini' Khul Husna Hnin Thandar Phyu Hnin Thazin Aung Husein, Salahuddin I Wayan Warmada Ikfi Maasyi Hanif Ilham Dharmawan Putra Irien Akinina Fatkhiandari Jutika Aditya Nugraha Nugraha Kamai, Toshitaka Kuncoro, Dwi Agus Mahendra, Fathan Hanifi Mada Maulana, Deviana Shinta Murti, Ardian Baroto Nugraha, Jutika Aditya Nugraha Nugroho Imam Setiawan Nurul Huda Phyu, Hnin Thandar Putra Pratama, Diyan Aditya Rama Tri Saksono Ratri, Diyaning Ridwan Umbara Salam Via Febriyanti Sao Sochan Shinta Dwi Novianti Shinta Maulana, Deviana Sia Pamela Dita Sochan, Sao Subagyo Pramumijoyo Sugeng Sapto Surjono Sunardi Sunardi Sunardi Sunarko Sunarko Sunarko Sunarko Tamado, Daniel Taufiq Muhammad Wijayanto Tee Xiong Thandar Phyu, Hnin Toshitaka Kamai Tri Puji Astuti Tri Puji Astuti Umbara, Ridwan Wahyu Wilopo Wakhid Khoiron Nugroho Warman, Gusti Imam Wawan Budianta Wijayanto, Taufiq Muhammad Wisnu Aji Dwi Kristanto Xiong, Tee Yan Adriansyah Yayi Ismanda Yunie Wiyasri