Surface subsidence due to underground mining operation under weak geological condition in Indonesia

et al. 2021

GEP

Self Cite

The stability of underground excavations has become an important issue in order to extend underground mining operations and extract deeper deposits. The increasing demand for Tin-Tungsten (Sn-W) for industry and its market price has created a motivation for mining companies to extract deep-seated Sn-W ore deposits in Myanmar. Thus, this paper aims to investigate the stability of underground openings, especially, the stope with considering the mining methods. To meet the objective, FLAC 3D 5.0 simulation was used for the assessment of stope under different stress ratios, 0.5, 1.0, and 1.5 for two types of underground mines; Open stoping and Cut and Fill stoping. The results show that the risk of instability of stope is high under the stress ratio of K = 0.5 than that of K = 1.0 and K = 1.5 in both mining methods. However, the stability of the stope in open stope method is lower than that of cut-and-fill method obviously. This result shows that the appropriate mining method has to be selected for extraction of Sn-W deposit carefully in terms of the balance of safety and cost.

Section: Introductionmentioning

confidence: 99%

Evaluation of Stope Stability in Underground Mine; Hermyingyi (Sn-W Deposit) Mine in Myanmar

Oo¹,

Sasaoka²,

et al. 2021

GEP

Self Cite

“…Both seams are excavated by longwall mining method. A few research have already been done in Indonesia coal resources for appropriated longwall development (Phanthoudeth et al, 2016;Pongpanya, Sasaoka, Shimada, Hamanaka, et al, 2017;Sasaoka et al, 2015). However, previous work has been limited to single seam longwall development.…”

Section: Introductionmentioning

confidence: 99%

Three-Dimensional Analysis of Gate-Entry Stability in Multiple Seams Longwall Coal Mine Under Weak Rock Conditions

Mao¹,

Sasaoka²,

et al. 2020

ESR

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A study of multiple seams longwall mining is proposed to investigate its applicability in Indonesia coal mine. The study area of this research is PT Gerbang Daya Mandiri (GDM) coal mine located in East Kalimantan Island. The study of seam interaction is crucial for developing multiple seams longwall mining especially when it comes to weak rock conditions which are usually found in most of the coal reserves in Indonesia. This paper will use numerical simulation to investigate the effect of the first mined-out seam on the development of the second coal seam gate-entry by considering a couple of key parameters including depth of the coal seam and interburden length. The simulation model consists of two main indicators for instability which include failure zone, the contour of safety factor. The results show that the effect of seam interaction on gate-entry has different intensity based on the thickness of the interburden and coal seam depth. This work also provided appropriate support configuration for maintaining the stability of gate-entry.

“…exports the in domest coal produ stopped th environme where the result, som of coal pro popular co dy of Cha Mine (Keilich, Seedsman, & Aziz, 2006;Zhang, Mitra, & Hebblewhite, 2006;Xu et al, 2013), only few researches have been carried out at the mine sites where the rocks are weak Sasaoka et al, 2015b). Therefore, the understanding of surface subsidence in poor ground conditions has still been limited.…”

Section: Introdumentioning

confidence: 99%

“…

Abstractcarried out at the mine sites where the rock strengths are medium to strong (Keilich, Seedsman, & Aziz, 2006;Zhang, Mitra, & Hebblewhite, 2006;Xu et al, 2013), only few researches have been carried out at the mine sites where the rocks are weak Sasaoka et al, 2015b). Therefore, the understanding of surface subsidence in poor ground conditions has still been limited.

The objective of this research was to study the characteristics of surface subsidence induced by longwall mining under poor ground conditions in Indonesia.

…”

mentioning

confidence: 99%

Study of Characteristics of Surface Subsidence in Longwall Coal Mine under Poor Ground Conditions in Indonesia

Pongpanya

Sasaoka²,

et al. 2017

ESR

Self Cite

Abstractcarried out at the mine sites where the rock strengths are medium to strong (Keilich, Seedsman, & Aziz, 2006;Zhang, Mitra, & Hebblewhite, 2006;Xu et al., 2013), only few researches have been carried out at the mine sites where the rocks are weak Sasaoka et al., 2015b). Therefore, the understanding of surface subsidence in poor ground conditions has still been limited.The objective of this research was to study the characteristics of surface subsidence induced by longwall mining under poor ground conditions in Indonesia. The effect of single panel and multi-panel mining at various depths, the influence of longwall panel and pillar widths, and the impact of backfill materials, were studied by means of numerical simulation using a three dimensional finite difference code "FLAC3D". The angle of draw (AoD) and maximum surface subsidence (S max ) were used to describe the characteristics of subsidence at the surface. MethodThe characteristics of surface subsidence were studied numerically using a three dimensional finite difference code "FLAC3D". FLAC3D is a numerical software which is widely used for analyzing stress and deformation around surface and underground openings conducted in both soil and rock. The software utilizes an explicit finite-difference formulation that can model complex behaviors of three-dimensional geomechanical problems (http://www.itascacg.com/software/flac3d, 2017). Effects of various mining conditions were considered in this study. Several models were constructed for numerical simulations. The models were 1330 m in width, 2000 m in length, and with various heights depending upon the mining depths. An example of a 200 m mining depth model is illustrated in Figure 4. The bottom of the model was fixed in the vertical direction, the sides were fixed in the horizontal direction, and the surface was set free in all directions. The vertical stress component was modeled as a function of overburden thickness or mining depth (P v =γH, γ is unit weight of overburden, and H is overburden thickness) (Hoek & Brown, 1980;Hoek, Kaiser, & Bawden, 1993;Hoek, 2006), while the horizontal stress component was assumed to be equal to the vertical stress. The elasto-plastic Mohr-Coulomb criterion was used as a failure criterion throughout the analyses. Table 1. In simulation, a coal panel was extracted step by step. After the excavation face moved forward, the caved area behind the coal face was filled by a very soft goaf material. The excavation steps were repeated until the coal panel was entirely extracted. ResultsIn EffectThe subsid three pane 130 m and increased w As the sec AoD exten because of Figure 8. From the results, it was observed that the less AoD and S max were generated after the first panel was mined, while the more AoD and S max were generated after the second and subsequent panels were mined. However, in case of a 50 m mining depth, the AoD and S max remained unchanged after three panels were mined. The reason of this phenomena can be explained by the ratio of pillar width to mining d...