Stability study of open mine slopes at pit 22 GN PT Kitadin Site Embalut, Kutai Kartanegara Regency, East Kalimantan Province

The stability of slope, both on the slope of work and the final slope, is a very important aspect of slope stability, both on the slope of work and the final slope in open pit mining activities. The inconsistency of the slopes will result in the collapse of rocks around the excavation site. This happens because the condition of the rock when it has not been excavated is generally balanced. However, due to the discontinuous patterns that occur other than naturally and also due to the mining activities such as excavation, blasting and others, cause a reduction in the retaining force of the rock on the slope results in the equilibrium of the force tends to shift and is not balanced. Study of the stability of the open pit highwall slope at PIT 22 GN PT Kitadin Site Embalut, Kutai Kartanegara Regency, East Kalimantan Province was carried out with the aim to know the rock characteristics, to calculate slope geometry stable safety factors, and to recognize the type of landslide using a bishop method. The results of the modeling consist of several heights and slopes, as well as angles that is formed. Section AA’ has a safety factor value of 1.387, section BB has a safety factor of 1.482, section BB' has a safety factor value of 1.390, section DD' has a safety factor value of 1.318, section EE has a safety factor value of 2,381, section FF' has a safety factor value of 2.426, section GG' has a safety factor value of 2.424, section HH 'has a safety factor value of 2.339.

KAJIAN GEOTEKNIK UNTUK OPTIMALISASI DESAIN TAMBANG BATUBARA MENGGUNAKAN LIMIT EQUILIBRIUM METHOD1)

ABSTRAKPT XYZ sebagai salah satu perusahaan yang bergerak dibidang pertambangan batubara yang terletak di Kabupaten Kutai Kartanegara, Provinsi Kalimantan Timur. Telah merencanakan pembuatan pit dan timbunan di suatu lahan yang belum dibuka. Oleh karena itu diperlukan studi geoteknik untuk menganalisa geometri lereng bukaan tambang serta timbunan yang telah direncanakan oleh pihak perusahaan.Kegiatan penelitian dilakukan dengan mengumpulkan data primer yang diperoleh dari pengeboran geoteknik, pengukuran muka air tanah dari 9 titik yang dianggap mewakili karakteristik massa tanah atau batuan dari beberapa pit. Lapisan batuan penyusun lereng tambang didominasi oleh batupasir dan batulempung, dijumpai pula batu lanau, carbon disamping batubara yang akan ditambang. Tanah atau batuan di lokasi penelitian termasuk kriteria batuan sedang sampai lemah, dibuktikan oleh pendekatan indeks kekuatan geologi dan sifat mekanik batuan. Pengukuran muka air tanah di daerah penelitian termasuk dalam kondisi jenuh dengan kedalaman MAT 0,88 - 11,975 meter.Penelitian dilakukan dengan jumlah pit sebanyak 7 pit, dan 13 penampang (section) yaitu penampang A-A’ sampai dengan penampang N-N’, yang merepresentasikan bentuk dari tiap pit penambangan batubara meliputi highwall dan lowwall. Kemantapan lereng untuk rencana desain tambang awal pada penampang A-A’ sampai dengan penampang N-N’ untuk lereng highwall dan lowwall faktor keamanannya terdapat yang sudah stabil namun masih dapat dioptimalkan, stabil dan tidak stabil, sehingga untuk lereng yang berada dalam kondisi stabil yang dapat dioptimalkan dilakukan desain ulang dengan kemiringan lereng yang curam dari sebelumnnya, kemudian untuk lereng yang tidak stabil dilakukan desain ulang dengan kemiringan lereng yang landai dari sebelumnnya. Rekomendasi lereng untuk penampang A-A’ lereng highwall yaitu overall slope angle 330 dan tinggi lereng 69,665 m serta untuk lereng lowwall yaitu overall slope angle 130 dan tinggi lereng 48,105 m, penampang B-B’ lereng highwall yaitu overall slope angle 290 dan tinggi lereng 34,139 m serta untuk lereng lowwall yaitu overall slope angle 220 dan tinggi lereng 40,109 m, penampang C-C’ lereng highwall yaitu overall slope angle 300 dan tinggi lereng 97,900 m serta untuk lereng lowwall yaitu overall slope angle 150 dan tinggi lereng 69,284 m, penampang D-D’ lereng highwall yaitu overall slope angle 490 dan tinggi lereng 77,023 m serta untuk lereng lowwall yaitu overall slope angle 70 dan tinggi lereng 132,16 m. Kata Kunci: Kestabilan Lereng, Highwall, Lowwall, Sidewall, Metode Kesetimbangan Batas ABSTRACT PT XYZ as one of the companies engaged in coal mining located in Kutai Kartanegara Regency, East Kalimantan Province. Planned construction of pits and waste dump on land that has not been cleared. Therefore a geotechnical study is needed to analyze the geometry of the mine opening slope and the pile planned by the company.Research activities carried out by collecting primary data obtained from geotechnical drilling, groundwater level measurements from 9 points that are considered to represent the characteristics of the soil mass or rock from several pits. Rock layers making up the mine slope are dominated by sandstone and claystone, silt stone, carbon in addition to the coal to be mined. The soil or rocks at the study site are of moderate to weak rock criteria, evidenced by the geological strength index approach and rock mechanical properties. Based on ground water level measurements in the study area included in saturated conditions with a MAT depth of 0.88 - 11.975 meters from the surface.The study was conducted with a total of 7 pits, and 13 section sections, namely A-A section to N-N section, which represent the shape of each coal mining pit including highwall and lowwall. Slope stability for the initial mine design plan on cross sections A-A 'to N-N cross sections for highwall and lowwall slopes there are safety factors that are already stable but can still be optimized, stable and unstable, so for slopes that are in stable conditions that are can be optimized redesigned with a steep slope from the previous, then for unstable slopes redesigned with a safety slope from the previous. Recommended slopes for cross section A-A 'highwall slopes are overall slope angle 330 and slope height 69,665 m and for lowwall slopes are overall slope angle 130 and slope height 48,105 m, cross section B-B' highwall slopes are overall slope angle 290 and slope height 34,139 m and for lowwall slopes namely overall slope angle 220 and slope height 40,109 m, cross section C-C 'highwall slope is overall slope angle 300 and slope height 97,900 m and for lowwall slopes are overall slope angle 150 and slope height 69,284 m, cross section D-D 'highwall slope is 490 overall slope angle and 77.023 m slope height and lowwall slope angle 70 overall and 132.16 m slope height. Key Word: Slope Stability, Highwall, Lowwall, Sidewall, Limit Equilibrium Method

The Influence of Structural Structures on Slope Stability at PT. Energi Batubara Lestari, South Kalimantan)

PT. Energi Batubara Lestari (EBL) is a coal mine that uses an open pit mining system, so it requiresslope security to create a safe and conducive mining environment. This study aims to analyze slopestability, the method used in this study is the boundary equilibrium method. The geological structure atPT. EBL has solids, sand lithology, loose sand, clay and coal, has a strong impact on slope stabilitybecause the more gaps, the more incoming water it will more easily affect weathered rocks so thatthey experience landslides. Slope stability analysis on the highwall side of the A-A side gets the FK1,851 value, the B-B side highwall side obtained by FK 1,676 and the highwall side of the C-obtainedside FK 1.54 indicates that the highwall slope is safe. And on the lowwall side the A-A side is obtainedFK 1,198, on the B-B side lowwall 'FK values obtained 0.94, and the C-C side lowwall side' is obtainedFK 1.27, indicating that on lowwall slopes in critical conidi. To make a stable or safe slope the slopegeometry is designed in lowwall areas with a high change and overall slope so that FK results areobtained: A-A design side 'lowwall slope 1,478, B-B design side' 1,447 lowwall slope while design sideC-C 'slope lowwall 1,497.

The Wave Effect Analysis Caused By Blasting Toward Highwall Slope Stability At Coal Mining, Pit 3000 Block 05 Sb 1, PT Trubaindo Coal Mining, Kutai Western District, East Kalimantan Province

PT Trubaindo Coal Mining (PT TCM) is a coal mining company located in West Kutai, East Kalimantan.Demolition of overburden layer is done by drilling and blasting can effect results primarily blastingground vibration for highwall slope stability. Controlled blasting activities undertaken in 3000 Pit Block05 using linedrill. Vibration measurement data obtained from the reading apparatus is not necessarilya factor affecting vibration highwall slope stability, but with the direction of propagation horizontalvibrations that cause the decrease highwall slope stability. The maximum horizontal accelerationarising from blasting activities as parameters that play a role in the stability of the slope obtained bylinking the PPA with the equation Amax = 0.5167 x PPA. Therefore, to determine the effect of groundvibration due to blasting for highwall slope stability modeling needs to be done cross-section A-A ', BB',C-C ', D-D' and E-E '. Results of prediction equations safety factor value of each cross-section asfollows: Section of A-A’, FK = 5,1489 amax 6 – 32,719 amax 5 + 79,933 amax 4 – 93,928 amax 3 + 54,189 amax 2 – 13,898 amax + 1,30852 Section of B-B’, FK = 0,4838 amax 6 – 3,0058 amax 5 + 7,0149 amax 4 – 7,6767 amax 3 + 4,4953 amax 2 – 2,4997 amax + 1,44549 Section of C-C’, FK = 1,2021 amax 6 – 7,4203 amax 5 + 16,907 amax 4 – 17,239 amax 3 + 8,0429 amax 2 – 2,8212 amax + 1,3628 Section of D-D’, FK = 5,279a amax 6 – 33,941 amax 5 + 84,105 amax 4 – 100,68 amax 3 + 59,648 amax 2 – 15,946 amax + 1,57907 Section of E-E’, FK = -1,9442 amax 6 + 11,453 amax 5 – 24,289 amax 4 + 20,677 amax 3 – 2,7313 amax 2 – 4,8741 amax + 1,65573The calculation results of critical maximum horizontal acceleration for every cross-section varies asthe follows: Section of A-A’, amax-critical = 0,007 g Section of B-B’, amax-critical = 0,118 g Section of C-C’, amax-critical = 0,062 g Section of D-D’, amax-critical = 0,025 g Section of E-E’, amax-critical = 0,09 gVariation is influenced by the thickness of the layer of top soil (top soil) and any cross-sectionalgeometry highwall slope.

Multiple-block plane shear slope failure

Field examination of highwall slope failures occurring in some coal strip mines in Alberta in association with bentonite has led to the concept of a multiple-block plane shear failure mode in which a series of individual block failures regresses back into the slope for distances up to five times the slope height. These failures cause a rapid deterioration of the bench from which the dragline operates, reduce productivity, and necessitate bench maintenance to provide a safe, stable bench prior to the next pass of the dragline.A probabilistic limiting equilibrium analysis was developed to predict the positions of successive failure blocks and its predictions were compared with slope geometry and laboratory strength data from a producing coal strip mine in which a failure was active.Two slope failures reported in the literature (Folkestone Warren landslips and an Oxford Clay brick pit, both in England) were reanalysed using the multiple-block plane shear failure mode, and it is suggested that this mode of failure offers an alternative explanation for the slope kinematics observed.Finally, the most effective means of reducing the probability of failure or controlling the extent of slope failure retrogression is by dewatering. Key words: slopes, failure, coal mining, bentonite, clay bands, plane shear, case history, probabilistic analysis.