scholarly journals Ground support with sprayed concrete in Canadian underground mines

1971 ◽  
Author(s):  
T W Verity ◽  
P Eng
Keyword(s):  
Underground Mines ◽  
Sprayed Concrete ◽  
Ground Support

scholarly journals Early-Age Strength Measurement of Shotcrete

2015 ◽  
Vol 2015 ◽  
pp. 1-10 ◽  
Author(s):  
Abbas Mohajerani ◽  
Daniel Rodrigues ◽  
Christian Ricciuti ◽  
Christopher Wilson
Keyword(s):  
Current Practice ◽  
Construction Material ◽  
Mining Industry ◽  
Early Age ◽  
Testing Methods ◽  
Strength Measurement ◽  
Sprayed Concrete ◽  
Ground Support ◽  
Strength Tests

Shotcrete or sprayed concrete is a special concrete designed for spraying onto a surface, as a construction material. With shotcrete application as a ground support system ever-present in both mining and tunnelling sectors, a major requirement of drive progression is to determine when it is safe to reenter beneath freshly sprayed concrete. Accurately determining this time is of paramount importance. Generally, this reentry time is based on measuring the developing strength of shotcrete until an adequate strength value is reached. The issue with current practice is that there is no widely accepted or generally preferred method that accurately assesses the shotcrete lining’s true early-age strength. However, there are a number of strength tests that are commercially available and used in the industry; these include the soil penetrometer, needle penetrometer, bolt screws, beam end testers, and drilled core samples. This paper researches into these testing methods and their characteristics in order to determine their accuracy, testing ranges, and suitability for in situ use in the tunnelling and mining industry. The investigation ultimately reveals that current methods all have substantial shortcomings. Based on these findings, recommendations are proposed for the applicable use of the current testing methods and recommendations for future improvements.

scholarly journals AUTOMATIC THICKNESS AND VOLUME ESTIMATION OF SPRAYED CONCRETE ON ANCHORED RETAINING WALLS FROM TERRESTRIAL LIDAR DATA

2016 ◽  
Vol XLI-B5 ◽  
pp. 521-526
Author(s):  
J. Martínez-Sánchez ◽  
I. Puente ◽  
H. GonzálezJorge ◽  
B. Riveiro ◽  
P. Arias
Keyword(s):  
Retaining Wall ◽  
Point Clouds ◽  
Retaining Walls ◽  
Volume Estimation ◽  
Rock Bolts ◽  
Rock Outcrops ◽  
Sprayed Concrete ◽  
Terrestrial Lidar ◽  
Ground Support ◽  
Before And After

When ground conditions are weak, particularly in free formed tunnel linings or retaining walls, sprayed concrete can be applied on the exposed surfaces immediately after excavation for shotcreting rock outcrops. In these situations, shotcrete is normally applied conjointly with rock bolts and mesh, thereby supporting the loose material that causes many of the small ground falls. On the other hand, contractors want to determine the thickness and volume of sprayed concrete for both technical and economic reasons: to guarantee their structural strength but also, to not deliver excess material that they will not be paid for. In this paper, we first introduce a terrestrial LiDAR-based method for the automatic detection of rock bolts, as typically used in anchored retaining walls. These ground support elements are segmented based on their geometry and they will serve as control points for the co-registration of two successive scans, before and after shotcreting. Then we compare both point clouds to estimate the sprayed concrete thickness and the expending volume on the wall. This novel methodology is demonstrated on repeated scan data from a retaining wall in the city of Vigo (Spain), resulting in a rock bolts detection rate of 91%, that permits to obtain a detailed information of the thickness and calculate a total volume of 3597 litres of concrete. These results have verified the effectiveness of the developed approach by increasing productivity and improving previous empirical proposals for real time thickness estimation.

scholarly journals Modified ground support with alternative fill material for ground control at munsar underground manganese mine of moil limited, India

2019 ◽  
Vol 2 (1) ◽  
pp. 69-77
Author(s):  
Ganesh Manekar ◽  
Dipankar Shome ◽  
Mukund Chaudhari
Keyword(s):  
Rock Mechanics ◽  
Underground Mining ◽  
Central India ◽  
Underground Mines ◽  
Manganese Ore ◽  
Opencast Mining ◽  
Mining Equipment ◽  
Ground Support ◽  
Ore Body ◽  
Fill Material

Abstract MOIL Limited is operating 7 underground and 3 opencast mines in central India and producing annually more than 1.3 million tonnes of various grades of manganese ore. The underground mines are operating at shallow – 90 m at Munsar mine to moderate – 353 m at Balaghat mine below the surface with horizontal cut and fill (HCF) or its variant method of stoping with post filling by hydraulic sand stowing. The Munsar mine is being worked underground since 1903. The opencast mining is presently stopped. The ore body below the opencast quarry is geological continuity of the area excavated in past by opencast method of mining. The underground mining is done through the adit in three levels i.e. 270’L, 220’L, 170’L and by incline in western part of the property at 70’L. The horizontal drift development has been developed in the manganese ore body with sill drive of 5 m above the sill pillar in lower level at 70’L and barrier pillar of 5 m thickness is left for protection of upper level at 170’L. Valuable mineral has been locked in sill pillar and therefore rock mechanics investigations have been carried out. On the basis of study now the drift development has been carried out in footwall rock at 70’L, (-) 30’L and below levels and it has improved the minable manganese ore by about 20%. In this modified HCF stope design, an alternative fill material in place of sand, which has been developed in house by use of overburden (OB) material after treatment, has been used for hydraulic stowing. The experimental trials find out that the alternative fill material of OB is more compact and forms a non-expansion floor for the men and machines in the stope. This will certainly help in the introduction of mobile underground mining equipment for drilling in the stopes and mechanical mucking, transportation and loading of the ROM. The paper presents rock mechanics investigations and future use of alternative fill material of overburden material after heat treatment for better safety and productivity at Munsar Mine of MOIL.

scholarly journals AUTOMATIC THICKNESS AND VOLUME ESTIMATION OF SPRAYED CONCRETE ON ANCHORED RETAINING WALLS FROM TERRESTRIAL LIDAR DATA

2016 ◽  
Vol XLI-B5 ◽  
pp. 521-526
Author(s):  
J. Martínez-Sánchez ◽  
I. Puente ◽  
H. GonzálezJorge ◽  
B. Riveiro ◽  
P. Arias
Keyword(s):  
Retaining Wall ◽  
Point Clouds ◽  
Retaining Walls ◽  
Volume Estimation ◽  
Rock Bolts ◽  
Rock Outcrops ◽  
Sprayed Concrete ◽  
Terrestrial Lidar ◽  
Ground Support ◽  
Before And After

When ground conditions are weak, particularly in free formed tunnel linings or retaining walls, sprayed concrete can be applied on the exposed surfaces immediately after excavation for shotcreting rock outcrops. In these situations, shotcrete is normally applied conjointly with rock bolts and mesh, thereby supporting the loose material that causes many of the small ground falls. On the other hand, contractors want to determine the thickness and volume of sprayed concrete for both technical and economic reasons: to guarantee their structural strength but also, to not deliver excess material that they will not be paid for. In this paper, we first introduce a terrestrial LiDAR-based method for the automatic detection of rock bolts, as typically used in anchored retaining walls. These ground support elements are segmented based on their geometry and they will serve as control points for the co-registration of two successive scans, before and after shotcreting. Then we compare both point clouds to estimate the sprayed concrete thickness and the expending volume on the wall. This novel methodology is demonstrated on repeated scan data from a retaining wall in the city of Vigo (Spain), resulting in a rock bolts detection rate of 91%, that permits to obtain a detailed information of the thickness and calculate a total volume of 3597 litres of concrete. These results have verified the effectiveness of the developed approach by increasing productivity and improving previous empirical proposals for real time thickness estimation.

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