Nuhindro Priagung Widodo
Program Studi Teknik Pertambangan, Fakultas Teknik Pertambangan Dan Perminyakan, Institut Teknologi Bandung, Bandung 40132, Jawa Barat, Indonesia

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Journal : INDONESIAN MINING PROFESSIONALS JOURNAL

Dynamic Analysis of Blasting Effect on Nanjung Tunnel Stability Alio Jasipto; Nuhindro Priagung Widodo; Ganda Marihot Simangunsong; Simon Heru Prasesetyo; Made Astawa Rai; Dhika Noor Pradhana; Dimas Agung Saputra
Indonesian Mining Professionals Journal Vol 2, No 1 (2020): April
Publisher : PERHAPI

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.36986/impj.v2i1.17

Abstract

This study aims to dynamically analyze blasting conducted in the Nanjung tunnel. Nanjung Tunnel is a twin tunnel that has a horseshoe-shaped section with each tunnel having a dimension of 10.2 m x 9.2 m, and 230 meters in length. The layers rock of this tunnel include silty clay, sandstone and dacite. Blasting was carried out on one of the tunnels consisting of dacite rock, having a 75-90% RQD and UCS 49-61 MPa. During the blast, PPV measurements were taken at several points around the tunnel using a minimate.Dynamic analysis is done by building a Nanjung Tunnel model on the RS2 software with the finite element method. Input data in this modeling is endeavored to approach actual conditions in the field, such as tunnel geometry, rock mass properties, and blasting plans carried out at STA 30-32 tunnels 2. This modeling is expected to produce PPV that is close to actual PPV and the results of this model will be continued to the stability analysis tunnel 1.Modeling results indicate that the tunnel 1 condition is stable during blasting. The stability of tunnel 1 based on smallest strength factor on the roof is around 2.6. Stability also seen from the strain level in dacite and sandstone rocks which are 0.07% and 0.38%. These strain levels are still permissible according to the Sakurai strain level diagram, 1983.
Analysis of Carbon Monoxide Gas Dilution on Horizontal Tunnel Front using Laboratory Scale Physical Model Addien Wisnu Harnoko; Nuhindro Priagung Widodo; Ahmad Ihsan
Indonesian Mining Professionals Journal Vol 1, No 1 (2019): NOVEMBER
Publisher : PERHAPI

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.36986/impj.v1i1.10

Abstract

Potential hazards that often occur in underground tunnels are dangerous and toxic gases, one of which is carbon monoxide (CO) which can be found in underground tunnels for example as a result of imperfect detonation on work surfaces. CO gas is very poisonous so it can cause death. This study aims to determine the spread of CO gas when diluting with tunnel ventilation in the horizontal front. This research was conducted on a physical model of the laboratory with a ratio of 1:10 compared to the actual tunnel, that is at the cross section of the model in the laboratory 40 cm x 40 cm. The effectiveness of dilution or dilution is indicated by the value of the diffusion coefficient, where the greater the diffusion coefficient, the more diffused the CO gas concentration, so the faster the CO gas concentration decreases. The parameters of the test conditions are the ratio of the duct to face distance (L/D) and the Reynolds number (Re) which shows the variation of air velocity in the tunnel work surface. Test results from the distribution of CO gas showed the influence of the configuration of the forcing duct and exhausting duct distances on the working front to the CO gas dilution. In this study also found the influence of Reynolds numbers on the value of the diffusion coefficient, that the greater the value of Re, the greater the value of E.
Stability Analysis of the Nanjung Water Diversion Twin Tunnels based on Convergence Measurement Simon Heru Prassetyo; Ganda Marihot Simangunsong; Ridho Kresna Wattimena; Made Astawa Rai; Irwandy Arif; Nuhindro Priagung Widodo; Dhika Noor Pradhana; Dimas Agung Saputra
Indonesian Mining Professionals Journal Vol 1, No 1 (2019): NOVEMBER
Publisher : PERHAPI

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.36986/impj.v1i1.11

Abstract

This paper focuses on the stability analysis of the Nanjung Water Diversion Twin Tunnels using convergence measurement. The Nanjung Tunnel is horseshoe-shaped in cross-section, 10.2 m x 9.2 m in dimension, and 230 m in length. The location of the tunnel is in Curug Jompong, Margaasih Subdistrict, Bandung. Convergence monitoring was done for 144 days between February 18 and July 11, 2019. The results of the convergence measurement were recorded and plotted into the curves of convergence vs. day and convergence vs. distance from tunnel face. From these plots, the continuity of the convergence and the convergence rate in the tunnel roof and wall were then analyzed. The convergence rates from each tunnel were also compared to empirical values to determine the level of tunnel stability. In general, the trend of convergence rate shows that the Nanjung Tunnel is stable without any indication of instability. Although there was a spike in the convergence rate at several STA in the measured span, that spike was not replicated by the convergence rate in the other measured spans and it was not continuous. The stability of the Nanjung Tunnel is also confirmed from the critical strain analysis, in which most of the STA measured have strain magnitudes located below the critical strain line and are less than 1%.
METODE GAS TRACER UNTUK EVALUASI EFISIENSI VENTILASI TAMBANG BAWAH TANAH Arif Widiatmojo; Nuhindro P Widodo; Kyuro Sasaki
Indonesian Mining Professionals Journal Vol 3, No 1 (2021): April
Publisher : PERHAPI

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.36986/impj.v3i1.28

Abstract

Ventilasi tambang bawah tanah mempunyai peran penting untuk memastikan kecukupan suplai udara segar untuk pekerja tambang, mesin bakar internal, melarutkan gas dan partikulat, maupun menjaga suhu dan kelembaban udara. Design yang tidak benar dapat  menyebabkan kebocoran dan resirkulasi udara, menurunkan efisiensi energi untuk sistem ventilasi secara total. Di lain hal, difusi turbulensi mengendalikan penyebaran gas dan partikulat.Makalah ini membahas penggunaan gas tracer untuk mengevaluasi efisiensi dari sistem ventilasi tambang. Dengan mencocokkan hasil pengukuran lapangan dengan simulasi numerik, kuantitas suplai udara yang terbuang disebabkan karena kebocoran dapat dievaluasi. Selain itu, laju pertukaran udara di front tambang juga di analisa berdasarkan data peluruhan gas. Sebagai hasil analisa, sekitar 53.5% udara bersih terbuang langsung melalui kipas utama. Sedangkan, laju pertukaran udara di salah satu front tambang, adalah sekitar 6.48 kali per jam.
STUDI PENGARUH UKURAN BUTIR BATUBARA DAN TINGKAT KEPADATAN BATUBARA TERHADAP POTENSI PEMBAKARAN SPONTAN PADA SKALA LABORATORIUM Study of the Effect of Coal Grain Size and Coal Compaction to the Spontaneous Combustion Potential at Laboratory Scale Nuhindro P Widodo
Indonesian Mining Professionals Journal Vol 2, No 1 (2020): April
Publisher : PERHAPI

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.36986/impj.v2i1.24

Abstract

ABSTRAKPembakaran spontan batubara dapat menjadi masalah yang serius terutama bagi kegiatan penambangan karena dapat menyebabkan terjadinya kebakaran pada penimbunan batubara atau ledakan gas metana pada tambang bawah tanah batubara. Penelitian kali ini akan dititikberatkan pada pengaruh ukuran butir batubara dan tingkat kepadatan batubara terhadap perilaku pembakaran spontan batubara. Ukuran butir yang digunakan dengan penelitian ini adalah -10+14 mesh, -60+80 mesh dan -170+200 mesh dengan tingkat kepadatan 0 kPa dan 50 kPa. Ukuran butir ini dipilih untuk mewakili kondisi ukuran butir relatif besar hingga kecil pada penimbunan batubara, sedangkan tingkat kepadatan diasumsikan berasal dari ground pressure dozer sebesar 50 kPa. Dalam penelitian kali ini, digunakan metode oksidasi adiabatik dengan mengalirkan gas oksigen dengan debit 0,05 L/menit pada tabung uji. Selain itu, dilakukan pula pengujian difusi oksigen untuk menentukan laju kenaikan konsentrasi oksigen pada masing-masing parameter. Ukuran butir dan tingkat kepadatan butiran batubara memiliki pengaruh besar terhadap terjadinya pembakaran spontan batubara. Semakin kecil ukuran percontoh maka nilai R70 semakin besar. Adanya pemadatan memiliki pengaruh yang berbeda terhadap nilai R70 pada ukuran butir yang berbeda. ABSTRACTSpontaneous combustion of coal can be a serious problem especially for mining activities because it can cause fires in coal stockpiling or methane gas explosions in coal underground mines. This research will focus on the influence of coal grain size and coal compaction on the spontaneous combustion behavior of coal. The grain sizes used in this study are -10 + 14 mesh, -60 + 80 mesh and -170 + 200 mesh with a compaction pressure of 0 kPa and 50 kPa. This grain size was chosen to represent the condition from large to small grain size in coal stockpile, while the compaction level is assumed to come from the dozer ground pressure of 50 kPa. In this study, an adiabatic oxidation method was used by flowing oxygen gas with a discharge of 0.05 L / min in the test tube. In addition, an oxygen diffusion test was also carried out to determine the rate of oxygen concentration increase for each parameter. Grain size and compaction level of coal grains have a major influence on the spontaneous combustion of coal. The smaller the sample size, the greater the R70 value. The presence of compaction has a different effect on the value of R70 at different grain sizes.