In worldwide mining practice, over 80 roof bolt designs have been uied out. However, none of them has proved satisfactory in rocks of different degrees of hardness. The Kuzbass Scientific-Research Coal Institute has been carrying out research on the design of roof bolts with the following main factors in mind: strength of fixation of anchorage in borehole; operational characteristics; expenditure of metal on construction of one set; technological ease of production; simplicity of installation; pos,~bility of repeated use; and cost of production. Tests of anchorage fixation strength were made on 28 typical designs.From the results, we developed roof bolts with improved supporting capacity: the anchorage fixation strength of these belts in their boreholes equals the tensile strength of the shank, namely, 12-18 tons. The belts are easy to produce and install and can be removed for re-use.In this article we glve a method of calculating the anchorage fixation strength of roof bolts of improved supporting capacity with special flanges on the split sleeve in the form of anlsoseeles triangle. If the conical wedge head of the shaft does not have parallel faces (Fig. la), the calculation Is performed in the following sequence.In the absence of a stop, the strength of fixation of the bolt in the borehole fs governed by the strength of fixation of the conical wedge head of the rod in the spat sleeves, since the strength of fixation of the split sleeves themselves in the borehole Is in this ease much higher. In calculating the strength of fixation we assume that in general not only the flanges but also the cylindrical parts of the sleeves between the flanges are pressed into the walls of the borehole.
THEUDC 622.281. '/4.00(571.63) The'Primorskugol' "group of mines has collieries inthe Artem, Maikhe, Tavrichanka, Suchan, Lipovtsy, Podgorodnenskii, and Khasan de posits in the Primorsldi Krai region, and in the Urgal deposit in the Khabarovsk region. The deposits are very scattered and have varied mining-geological conditions.The seams of brown and hard coals differ in thickness and in angle of dip (from 0 to 90*), and have varying structure and erratic hypsometry. The seams in the Artem, Maikhe, Tavrichanka, Khasan, North Suchan, Lipovtsy, and Urgal deposits are flat-lying, while those in the Staryi Suchan and Podgorodnenskii deposits are inclined or steeply-dipping.The country rocks of the Artem, Maikhe, and Tavrichanka deposits (with rare exceptioIlS) are weak and unstable, and rapidly lose strength on exposure, being rapidly extruded into the working.The Suchan deposit is unique in its structural disruption. We find veins of igneous rocks intersecting or displacing the coal seams. The rather hard rocks of Staryi such,an are unstable in places owing to heavy fissuring and the floor rocks of the steeply dipping seams tend to creep. There are zones of coal with weak cleavage. In North Suchan there is a marked false roof.The coal and rock in the Lipovtsy deposit are fairly hard.The country rocks of the seams in the Urgal deposit are very hard.AII the seams in these deposits are gassy. The pits of Staryi Suchan and the Podgorodnenskii and Tavrichanka deposits are in the top category for methane. Some are liable to gas bursts (Staryi Suchan and the "Podgorodnenskaya" pit) and shock bumps (the staryi Suchan pits).The deposits are relatively dry.The depth of the mine workings is mainly 200-350 m, but in the staryi Suchan pits reaches 600-700 m (in the "Glubokaya" pit).The development workings are supported by wooden props, metal frames, arches, rings, bolts, and gunite linings. About 51% of all the supported workings have metal supports of the prop type. Wider use of metal supports is being held up at present owing to the high metal consumption and inadequate efficiency of this type in the difficult mining-geological conditions of the Artem, Tavrichanka, and Matkhe deposits.In the main and level drifts, metal ring supports are mainly set at intervals of 0.5-0.7 m. Nevertheless, owing to heavy rock pressure they undergo marked deformations. Over one year, the supports in about 10 km of main roadways are replaced or repaired.In working the seams, about 40 km of workings with metal supports are abandoned. Most of the extracted metal support frames are beyond repair owing to severe deformation and have to be scrapped.Kuznetsk Scientific-Research Coal Institute.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.