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MODELS FOR PHYSICAL AND NUMERICAL SLOPE FAILURE OF LOOSE SAND UNDER DYNAMIC LOADING ZULFAHMI ZULFAHMI
Indonesian Mining Journal Vol 15, No 3 (2012): INDONESIAN MINING JOURNAL Vol. 15 No. 3 October 2012
Publisher : Puslitbang tekMIRA

Excessive vibration that causes damage to model the medium such as mine slope can physically and numeri- cally be modelled. The slope of this study simply represents the actual view of the slopes that has a smaller size than the actual one, while the numerical model is relates to a mathematical form of slope condition that based on physical and mechanical data of the medium. The slope failure has experimentally been built several variations. Effect of vibration is echieved by connecting the models into the vibration instrument with bearing that can horizontally move free in line within the determined track. The instrument is attached to a spring that can pull the model to side out. The spring is placed in an iron frame. Proviously, the slope has been formed in critical condition one (angle of 30°). Physical model and laboratory test results were used as an input for numerical modelling of the slope failure. Based on the numerical analysis, the SRF was 0.47 for D equal to 2 cm g around 0.0025. If the g’s were around 0.0057 and 0.0088, the obtained SRF for both g’s were 0.44 and0.41 respectively. While the D of 4 cm and g of 0.0024 came the SRF of 0.54, the g of 0.0064 derived the SRF of 0.48, and the g of 0.0106 obtained the SRF of 0.44. For D equal to 2 cm and g 0.0024, 0.0106; the obtained SRF was 0.54, 0.48 and 0.44 respectively. Increasing the D to 6 cm within variation of g from 0.0025, 0.0062 and 0.0106, the SRF was 0.51, 0.48 and 0.44 respectively. It is assumed that there is a correlation between the thickness of quartz sand layer and the decrease of SRF value. The correlation also occurs between the increase in vibration (g value) and the SRF.

APPLICATION OF SIMPLE DISPLACEMENT MONITORING SYSTEM FOR ROCK/SOIL MOVEMENT AT BINUNGAN MINE OPERATION OF PT. BERAU COAL ZULFAHMI ZULFAHMI
Indonesian Mining Journal Vol 10, No 2 (2007): INDONESIAN MINING JOURNAL Vol. 10 No. 2 June 2007
Publisher : Puslitbang tekMIRA

This monitoring result illustrates the real slope stability and could be used as datat for back analysis to obtain the real shear strength (c and ö).Study of monitoring system application to detect soil/rock movement at mine slope was conducted bya team from tekMIRA in 2006. The location of trial run was Binungan Mine Operation, PT. Berau Coal. The team used combinations of simple, accurate and relatively low cost monitoring equipment consists of radio modem, data logger and potential trans- ducer. Potential transducers were connected to the observation points using a wire line. When the movement occurs along the mine slope, the wire line will cause a difference potentiometer voltage. The results show a good value of linearity with value of r-square between 0.964 and 0.98

STUDY OF COMPRESSIONAL AND SHEAR WAVE VELOCITY TESTS IN THE LABORATORY AND FIELD APPLIED TO SEDIMENTARY ROCKS OF RANTAU NANGKA DISTRICT, SOUTH KALIMANTAN Zulfahmi Zulfahmi
Indonesian Mining Journal Vol 16, No 2 (2013): INDONESIAN MINING JOURNAL Vol. 16 No. 2 June 2013
Publisher : Puslitbang tekMIRA

Compressional (Vp) and shear (Vs) wave velocities within rocks are often investigated by testing in the laboratory because it is easier and cheaper. However, it is more confidence with investigation results derived from the field due to the actual situation and conditions. In the laboratory, the wave velocities are commonly measured using ultrasonic pulse velocities test. But in the field, the velocities are commonly measured directly by several methods such as cross-hole seismic, down-hole seismic, suspension logging, seismic reflection, seismic refraction and spectral analysis of the surface wave. In the present study of field insitu tests, it has used down-hole seismic method. The field insitu test is more expensive than the laboratory test. Hence, this study would evaluate and compare data derived from both of laboratory and field insitu tests. Based on the measurements correlation, it is found that regression equation for each parameter are ... for compressional wave velocities, ... for shear wave velocities, xxxxx for shear modulus, ... for ... modulus of elasticity, for bulk modulus and ... for Lame constants. This equation can be applied to correct the laboratory test data in order to get close results between the laboratory and field insitu tests.

SUBSIDENCE AND HEAT PROPAGATION MODELING ON THE UNDERGROUND COAL GASIFICATION (CASE STUDY AT MUARA ENIM FORMATION, SOUTH SUMATERA) Zulfahmi Zulfahmi; Ildrem Syafri; Abdurrokhim Abdurrokhim; Ridho Kresna Wattimena
Indonesian Mining Journal Vol 23, No 2 (2020): INDONESIAN MINING JOURNAL, Vol. 23 No. 2, October 2020
Publisher : Puslitbang tekMIRA

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.30556/imj.Vol23.No2.2020.1132

One of the important issues to study underground coal gasification (UCG) is the prediction of surface subsidence. Several parameters that influence these conditions are the thickness of cap rock, the physical and mechanical characteristics, the structure condition, the minerals composition of the rock, and external conditions. This study had been carried out simulation and modeling to determine the level of surface subsidence risk and the effect of high temperatures due to the activities. The modeling results show that the thickness of the rock above the UCG coal seam greatly affects the surface subsidence. The depth is more than 200 m and found that the SF value is 1.59 which indicates UCG reactor depth of ≥ 200 m is safe from the risk of subsidence. From the characteristic aspect of the cap rock, the claystone types which not contain kaolinite minerals are more prone to collapse than those of contain kaolinite minerals. From this models, the gasifier at 150 m depth was estimated that there will be a decline of -7.23 m, and the minimum subsidence is at 275 m about 0.1 m. The heat propagation modeling results show that at 50 m the temperature is estimated to be 213- 289°C, but if the thickness of the cap rock is > 200 m depth, the temperature is around 29-28°C.

STUDY OF COMPRESSIONAL AND SHEAR WAVE VELOCITY TESTS IN THE LABORATORY AND FIELD APPLIED TO SEDIMENTARY ROCKS OF RANTAU NANGKA DISTRICT, SOUTH KALIMANTAN Zulfahmi Zulfahmi
Indonesian Mining Journal Vol 16 No 2 (2013): INDONESIAN MINING JOURNAL Vol. 16 No. 2 June 2013
Publisher : Balai Besar Pengujian Mineral dan Batubara tekMIRA

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.30556/imj.Vol16.No2.2013.426

Compressional (Vp) and shear (Vs) wave velocities within rocks are often investigated by testing in the laboratory because it is easier and cheaper. However, it is more confidence with investigation results derived from the field due to the actual situation and conditions. In the laboratory, the wave velocities are commonly measured using ultrasonic pulse velocities test. But in the field, the velocities are commonly measured directly by several methods such as cross-hole seismic, down-hole seismic, suspension logging, seismic reflection, seismic refraction and spectral analysis of the surface wave. In the present study of field insitu tests, it has used down-hole seismic method. The field insitu test is more expensive than the laboratory test. Hence, this study would evaluate and compare data derived from both of laboratory and field insitu tests. Based on the measurements correlation, it is found that regression equation for each parameter are ... for compressional wave velocities, ... for shear wave velocities, xxxxx for shear modulus, ... for ... modulus of elasticity, for bulk modulus and ... for Lame constants. This equation can be applied to correct the laboratory test data in order to get close results between the laboratory and field insitu tests.

MODELS FOR PHYSICAL AND NUMERICAL SLOPE FAILURE OF LOOSE SAND UNDER DYNAMIC LOADING ZULFAHMI ZULFAHMI
Indonesian Mining Journal Vol 15 No 3 (2012): INDONESIAN MINING JOURNAL Vol. 15 No. 3 October 2012
Publisher : Balai Besar Pengujian Mineral dan Batubara tekMIRA

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.30556/imj.Vol15.No3.2012.447

Excessive vibration that causes damage to model the medium such as mine slope can physically and numeri- cally be modelled. The slope of this study simply represents the actual view of the slopes that has a smaller size than the actual one, while the numerical model is relates to a mathematical form of slope condition that based on physical and mechanical data of the medium. The slope failure has experimentally been built several variations. Effect of vibration is echieved by connecting the models into the vibration instrument with bearing that can horizontally move free in line within the determined track. The instrument is attached to a spring that can pull the model to side out. The spring is placed in an iron frame. Proviously, the slope has been formed in critical condition one (angle of 30°). Physical model and laboratory test results were used as an input for numerical modelling of the slope failure. Based on the numerical analysis, the SRF was 0.47 for D equal to 2 cm g around 0.0025. If the g’s were around 0.0057 and 0.0088, the obtained SRF for both g’s were 0.44 and0.41 respectively. While the D of 4 cm and g of 0.0024 came the SRF of 0.54, the g of 0.0064 derived the SRF of 0.48, and the g of 0.0106 obtained the SRF of 0.44. For D equal to 2 cm and g 0.0024, 0.0106; the obtained SRF was 0.54, 0.48 and 0.44 respectively. Increasing the D to 6 cm within variation of g from 0.0025, 0.0062 and 0.0106, the SRF was 0.51, 0.48 and 0.44 respectively. It is assumed that there is a correlation between the thickness of quartz sand layer and the decrease of SRF value. The correlation also occurs between the increase in vibration (g value) and the SRF.

APPLICATION OF SIMPLE DISPLACEMENT MONITORING SYSTEM FOR ROCK/SOIL MOVEMENT AT BINUNGAN MINE OPERATION OF PT. BERAU COAL ZULFAHMI ZULFAHMI
Indonesian Mining Journal Vol 10 No 2 (2007): INDONESIAN MINING JOURNAL Vol. 10 No. 2 June 2007
Publisher : Balai Besar Pengujian Mineral dan Batubara tekMIRA

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.30556/imj.Vol10.No2.2007.620

This monitoring result illustrates the real slope stability and could be used as datat for back analysis to obtain the real shear strength (c and ö).Study of monitoring system application to detect soil/rock movement at mine slope was conducted bya team from tekMIRA in 2006. The location of trial run was Binungan Mine Operation, PT. Berau Coal. The team used combinations of simple, accurate and relatively low cost monitoring equipment consists of radio modem, data logger and potential trans- ducer. Potential transducers were connected to the observation points using a wire line. When the movement occurs along the mine slope, the wire line will cause a difference potentiometer voltage. The results show a good value of linearity with value of r-square between 0.964 and 0.98

SUBSIDENCE AND HEAT PROPAGATION MODELING ON THE UNDERGROUND COAL GASIFICATION (CASE STUDY AT MUARA ENIM FORMATION, SOUTH SUMATERA) Zulfahmi Zulfahmi; Ildrem Syafri; Abdurrokhim Abdurrokhim; Ridho Kresna Wattimena
Indonesian Mining Journal Vol 23 No 2 (2020): INDONESIAN MINING JOURNAL, Vol. 23 No. 2, October 2020
Publisher : Balai Besar Pengujian Mineral dan Batubara tekMIRA

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.30556/imj.Vol23.No2.2020.1132

One of the important issues to study underground coal gasification (UCG) is the prediction of surface subsidence. Several parameters that influence these conditions are the thickness of cap rock, the physical and mechanical characteristics, the structure condition, the minerals composition of the rock, and external conditions. This study had been carried out simulation and modeling to determine the level of surface subsidence risk and the effect of high temperatures due to the activities. The modeling results show that the thickness of the rock above the UCG coal seam greatly affects the surface subsidence. The depth is more than 200 m and found that the SF value is 1.59 which indicates UCG reactor depth of ≥ 200 m is safe from the risk of subsidence. From the characteristic aspect of the cap rock, the claystone types which not contain kaolinite minerals are more prone to collapse than those of contain kaolinite minerals. From this models, the gasifier at 150 m depth was estimated that there will be a decline of -7.23 m, and the minimum subsidence is at 275 m about 0.1 m. The heat propagation modeling results show that at 50 m the temperature is estimated to be 213- 289°C, but if the thickness of the cap rock is > 200 m depth, the temperature is around 29-28°C.

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