SPECIFIC PRESSURE ON THE SUPPORT ESTIMATION WITH THE ACCOUNT OF ROCK DESTRUCTION ZONE AROUND THE DEVELOPMENT WORKING

This article presents the results of laboratory tests regarding the influence of high temperatures on changes in the strength and structural parameters of rocks that are present in the immediate vicinity of a gasification channel. Sandstone and claystone samples were heated at 300 °C, 600 °C, 900 °C and 1200 °C. Additionally, the heated samples were placed in water for 24 h. The results of the laboratory tests were used in the numerical simulation using RS2 software. The main goal of modeling was to determine the extent of the rock destruction zone around the gasification channel for dry and wet rock masses. In the numerical simulations, three widths of the gasification channel and three ranges of high-temperature impact were modeled. On the basis of the obtained results, it was found that the extent of rock destruction, both in the roof and in the floor, is greater by several percent for a wet rock mass. For the first time, this research presents the effect of water on heated rock samples in terms of the underground coal gasification process. The results of laboratory tests and numerical simulations clearly indicate a reduction in strength, deformation and structural parameters for the temperature of 1200 °C.

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STUDIES OF THE SHAPED CHARGES EFFECT WITH A HEMISPHERICAL ECCENTRIC SHAPE RECESS FOR THE ROCKS DESTRUCTION

Sustainable Development of Mountain Territories ◽

10.21177/1998-4502-2021-13-2-281-291 ◽

2021 ◽

Vol 13 (2) ◽

pp. 281-291

Author(s):

Dam THANG ◽

◽

Vladimir BELIN ◽

Tran DOANH ◽

◽

...

Keyword(s):

Short Circuit ◽

Utilization Rate ◽

Destructive Effect ◽

Rock Destruction ◽

Large Loss ◽

Different Types ◽

Destruction Zone ◽

Explosive Charges ◽

Optimal Effect ◽

Destruction Of Rocks

The method of outdoor installation of explosive charges is usually used in the destruction of rocks in conditions in which the method of drilling and blasting using borehole or borehole charges is difficult to apply due to objective conditions. The productivity of rock destruction by the outdoor installation of a concentrated charge is very low. This is due to the fact that such an explosion is characterized by a large loss of energy in the environment. The destruction of rocks by an explosion using shaped charges (CW) to destroy the rock is one solution to increase the useful energy of the destruction of the rock compared to charges placed outside. To achieve the optimal effect of destruction of the rock by cumulative charges, it is necessary to, so that for each type of rock, a specific type of shaped charges can be determined with the appropriate performance and efficiency of the use of explosives. The stronger the rock, the more efficient the short-circuit should be, and vice versa. Thus, for effective rock crushing, it is necessary to develop and produce a number of different types of shaped charges. The use of shaped explosive charges allows you to increase the utilization rate of the useful energy of the explosion and increase the destruction zone of the rock. At a fixed mass of the explosive, the destructive effect of the explosive charge placed on the surface of the rock, it depends on the shape of the charge and the geometric parameters of the charge. Shaped charges with an eccentric hemispherical shape have a coefficient of use of the useful energy of the explosion for the destruction of rock, more than 2.4 times compared to conventional concentrated charges of the same mass.

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The Influence of Room and Pillar Method Geometry on the Deposit Utilization Rate and Rock Bolt Load

Energies ◽

10.3390/en12244770 ◽

2019 ◽

Vol 12 (24) ◽

pp. 4770 ◽

Cited By ~ 11

Author(s):

Krzysztof Skrzypkowski

Keyword(s):

Three Dimensional ◽

Rock Bolt ◽

Utilization Rate ◽

Variable Geometry ◽

Rock Destruction ◽

Destruction Zone ◽

Increased Strength ◽

Rock Bolt Support ◽

Bolt Spacing ◽

Bolt Support

In this article, a model of ore deposit in form of a lense carried out in the MineScape program, is presented. The lense had a thickness of 30 m, length along the strike 200 m, and the depth buried was for 80 m to 110 m below the surface. In the first layer, counting from the lowest level, a room and pillar method with variable geometry was designed. The width and length dimensions for rooms and pillars were: 4 m, 5 m and 6 m, respectively. For the selected part of the deposit, three variants of the system with variable geometry of rooms and pillars were designed, for which the deposit utilization coefficient was determined. The next stage of the research was to determine the influence of the geometry of the pillars and rooms on the range of the rock destruction zone around room excavations. For this purpose, numerical calculations using the three-dimensional Examine 3D program, based on the boundary element method, were made. The results of numerical tests were used to calculate the load of the rock bolt support, which is currently used in the zinc and lead underground mine “Olkusz-Pomorzany” in Poland. Currently in the mine, the bolt spacing is 1 m × 1 m, and the technology for fixing the bolt rod is based on resin cartridges that completely fill the bolt hole. In order to spread the spacing of the rock bolt support and to apply segmental fixing of the bolt rod, in the laboratory tests, rock bolt supports with increased strength were tested. Based on the results obtained, it was found that the rock bolt can be installed segmentally, using a cement grout, and its spacing can be increased to 2 m.

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Determination of the rock destruction depth by PDC cutters with account of the medium resistance

Construction of Oil and Gas Wells on Land and Sea ◽

10.33285/0130-3872-2020-5(329)-23-27 ◽

2020 ◽

pp. 23-27

Author(s):

V.V. Neskoromnykh ◽

◽

M.S. Popova ◽

A.V. Chikhotkin ◽

A.E. Golovchenko ◽

...

Keyword(s):

Rock Destruction ◽

Medium Resistance

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ANALYSIS OF STAND RESEARCH RESULTS OF AXIAL DYNAMIC FORCE IN DRILLING BY THREE ROLLER CONE BIT

PRECARPATHIAN BULLETIN OF THE SHEVCHENKO SCIENTIFIC SOCIETY Number ◽

10.31471/2304-7399-2019-1(53)-81-93 ◽

2019 ◽

pp. 81-93

Author(s):

В. М. Мойсишин ◽

M. V. Lyskanych ◽

R. A. Zhovniruk ◽

Ye. P. Majkovych

Keyword(s):

Low Frequency ◽

Maximum Energy ◽

Dynamic Force ◽

Low Frequency Oscillation ◽

Drilling Tool ◽

Rock Destruction ◽

Frequency Components ◽

Harmonic Components ◽

Experimental Values ◽

Harmful Effects

The purpose of the proposed article is to establish the causes of oscillations of drilling tool and the basic laws of the distribution of the total energy of the process of changing the axial dynamic force over frequencies of spectrum. Variable factors during experiments on the classical plan were the rigidity of drilling tool and the hardness of the rock. According to the results of research, the main power of the process of change of axial dynamic force during drilling of three roller cone bits is in the frequency range 0-32 Hz in which three harmonic frequency components are allocated which correspond to the theoretical values of low-frequency and gear oscillations of the chisel and proper oscillations of the bit. The experimental values of frequencies of harmonic components of energy and normalized spectrum as well as the magnitude of the dispersion of the axial dynamic force and its normalized values at these frequencies are presented. It has been found that with decreasing rigidity of the drilling tool maximum energy of axial dynamic force moves from the low-frequency oscillation region to the tooth oscillation area, intensifying the process of rock destruction and, at the same time, protecting the tool from the harmful effects of the vibrations of the bit. Reducing the rigidity of the drilling tool protects the bit from the harmful effects of the vibrations generated by the stand. The energy reductions in these fluctuations range from 47 to 77%.

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Dental Implant Site Drilling and Induced Morphological Changes Correlated with Temperature in Pig’s Rib Used as the Human Jaw Model

Applied Sciences ◽

10.3390/app11062493 ◽

2021 ◽

Vol 11 (6) ◽

pp. 2493

Author(s):

Karol Kirstein ◽

Michalina Horochowska ◽

Jacek Jagiełło ◽

Joanna Bubak ◽

Aleksander Chrószcz ◽

...

Keyword(s):

Bone Tissue ◽

Morphological Changes ◽

Bone Destruction ◽

Microscopic Investigation ◽

In Vivo Studies ◽

Drilling Speed ◽

Tissue Destruction ◽

Destruction Zone ◽

Jaw Model

The bone tissue destruction during drilling is still one of the crucial problems in implantology. In this study, the influence of drilling speed, coolant presence, and its temperature on bone tissue was tested using swine rib as a biological model of human jaws. The same method of drilling (with or without coolant) was used in all tested samples. The microscopic investigation estimated the size of the destruction zone and morphology of bone tissue surrounding the drilling canal. The achieved results were statistically elaborated. The study proved that the optimal drilling speed was ca. 1200 rpm, but the temperature of the used coolant had no significant influence on provoked bone destruction. Simultaneously, the drilling system without coolant compared to this with coolant has statistical importance on drilling results. Further in vivo studies will verify the obtained results.

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