A new design of support for burst-prone rock mass in underground ore mining

Skrzypkowski, Krzysztof

doi:10.1051/e3sconf/20187100006

Cited by 20 publications

(10 citation statements)

References 5 publications

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“…Roof bolting is used in both ore and coal mining, installed segmentally or over the whole length using quick-setting and slow-setting resin cartridges. Glue-in roof bolting is installed in long-term preparatory excavations, short-term mining excavations, and in the fractured rock mass, where the expansive head cannot expand against the walls of the bolt hole [1]. In underground mines it often happens that locally, along the boreholes drilled for the bolt, fractured zones (or even bigger gaps) are met, so the diameter is oversized, the contact may be insufficient, and finally, the expansion head will not be effective.…”

Section: Introductionmentioning

confidence: 99%

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

et al. 2019

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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 Bolesław 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.

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Section: Introductionmentioning

confidence: 99%

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

et al. 2019

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“…In room and pillar methods, where excavations intersect each other, there is a stress concentration area, and the damage area of the roof rock mass is the largest, which results in developing long, reinforced rock bolt supports, both with expansion and installed with the use of adhesive resin cartridges and cement binder in these areas [20,21]. In situations where there are large rock deformations, it is necessary to use yieldable bolts (Figure 1), which will stop the rock mass falling into the excavation without serious damage, and at the same time the rock bolt support will additionally serve as an energy absorbing system [22,23]. Holding the rocks up by the rock bolt support when serious deformations appear: 1-original shape of the room; 2-shape of the room after rock mass deformation; 3-yieldable rock bolt support.…”

Section: Introductionmentioning

confidence: 99%

Modified Rock Bolt Support for Mining Method with Controlled Roof Bending

et al. 2020

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The article presents methods of making the rock bolt support more yieldable, especially for a stratified roof. Alongside the increasing depth of exploitation of raw material deposits, rock bolt support units are more often designed taking into account more intensive deformations and displacements of underground excavations. In the article, a room and pillar method with mined roof bending and roof reinforcement with bolt patterns of 1 m × 1 m, 1.5 m × 1.5 m and 2 m × 2 m is presented. Moreover, the laboratory tests included 1.8 m long bolts, which were embedded segmentally on the lengths of 100 mm, 150 mm and 200 mm were tested. Based on the load–displacement characteristics, the deformation energy for flat and profiled dome bearing plates was calculated. Making the segmentally embedded resin rock bolt support yieldable enabled it to perform additional work. Furthermore, it was found that rock bolt support with a dome bearing plate took over 2.5 times more energy compared to a rock bolt support equipped with a flat bearing plate.

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“…Scholars have also conducted a lot of research on rigid support technology. For example, under the action of dynamic load, adding yield element can significantly improve the coordination of bolt support and arch yield support [3,4]. From the effect of field application, the rigid support is difficult to ensure the stability of the whole system and the integrity of the surrounding rock when facing the sudden vibration and impact of the surrounding rock [5,6].…”

Section: Introductionmentioning

confidence: 99%

Local Thickening and Friction Reducing to Constant Resistance in a Prefolded Energy Absorption Device

Song

et al. 2020

Shock and Vibration

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The energy absorption support for impact resistance used in mining engineering is a prefolded energy absorption device. In this paper, through the quasistatic compression test and numerical simulation, the relationship between the deformation process, load-displacement curve, and plastic strain of the original prefolded energy absorbing device is studied. It is found that the concave side stiffness has an obvious effect on the first and second descending sections of the load-displacement curve, and the friction coefficient has an obvious effect on the second ascending section of that. In order to make the prefolded energy absorption device reach the state of constant resistance where the reaction load does not fluctuate or the fluctuation is small in the crushing process, the plastic strain is restrained by thickening the local area of the concave side, which effectively reduces the descending amplitude of the load-displacement curve. Whether continuoues deformation occurs is affected by the friction coefficient. Finally, a constant resistance energy absorption device is designed by thickening the concave side and reducing the friction coefficient. Compared with the original structure, the maximum bearing capacity of the constant resistance energy absorption device is basically unchanged, the average bearing capacity is increased by 29%, the total energy absorption is increased by 111%, the specific energy absorption is increased by 119%, and the load-displacement curve variance is reduced to 3% of the original structure.

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A new design of support for burst-prone rock mass in underground ore mining

Cited by 20 publications

References 5 publications

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

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

Modified Rock Bolt Support for Mining Method with Controlled Roof Bending

Local Thickening and Friction Reducing to Constant Resistance in a Prefolded Energy Absorption Device

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