Flexibility and Load-Bearing Capacity of Roof Bolting as Functions of Mounting Depth and Hole Diameter

Krzysztof Skrzypkowski, Waldemar Korzeniowski, Krzysztof Zagórski and Anna Zagórska
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Krzysztof Skrzypkowski: AGH University of Science and Technology, Faculty of Mining and Geoengineering, Mickiewicza 30 av. 30-059 Cracow, Poland
Waldemar Korzeniowski: AGH University of Science and Technology, Faculty of Mining and Geoengineering, Mickiewicza 30 av. 30-059 Cracow, Poland
Krzysztof Zagórski: AGH University of Science and Technology, Faculty of Mechanical Engineering and Robotics, Mickiewicza 30 av. 30-059 Cracow, Poland
Anna Zagórska: Polish Academy of Sciences, Institute of Geological Sciences, Research Centre in Cracow, Senacka 1, 31-002 Cracow, Poland

Energies, 2019, vol. 12, issue 19, 1-23

Abstract: This paper presents the results of laboratory tensile testing of segmentally-installed glue-in roof bolting. We studied roof bolting of the type Olkusz-16A (Boltech Sp. z o.o., ZGH Boles?aw S.A., Bukowno, Poland), additionally equipped with a steel rod coil, which was mounted in steel cylinders filled with a concrete mixture using multi-part resin cartridges with a diameter of 0.024 m and length of 0.045 m. The mounting depths were 0.1 m and 0.2 m, respectively. Our main purpose was to determine the effect of the bolt hole diameter, which assumed the values 0.028 m, 0.032 m, 0.035 m, and 0.037 m, respectively, on the load-bearing capacity of the roof bolting in relation to the mounting depth. We found that the mounting depth of 0.2 m was sufficient for the roof bolting to exhibit its full load and displacement properties for all four diameters of the bolt hole. To determine whether the roof bolting was capable of transferring the load in situ, we presented the results of the predicted load on the roof bolting applied in a room and pillar mining method in an underground mine of zinc and lead ore deposits. Our objective was to determine the influence of the room and pillar mining method geometry on the range of the fault zone of rocks around pits. We designed the deposit excavation model using the Examine3D numerical modeling software, which is based on the boundary element method. We created three-dimensional models for three variants of working space opening widths: featuring two, three, and four rows of rooms. The geometry of rooms and pillars corresponded to the mine conditions; the width, height, and length parameters were all 5 m. We determined the strength, strain, and structural parameters of the rock mass on the basis of laboratory studies of the drill core and rock forms collected from the room longwall. We used the strength factor to specify the maximum range of the fault zone of rocks around pits. In the last stage of research, we compared the load value obtained based on numerical testing with the maximum load obtained in the tensile strength tests of the roof bolting and determined the safety factor of the segmentally-installed roof bolting.

Keywords: segmentally-installed roof bolting; hole diameter; room and pillar mining method; load-bearing capacity of roof bolting; laboratory tests; numerical modeling (search for similar items in EconPapers)
JEL-codes: Q Q0 Q4 Q40 Q41 Q42 Q43 Q47 Q48 Q49 (search for similar items in EconPapers)
Date: 2019
References: View references in EconPapers View complete reference list from CitEc
Citations: View citations in EconPapers (10)

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