METHODOLOGY FOR ESTIMATION OF ROCK MASS AND MINE SHAFT LINING STRAIN STATE DURING PILLAR RECOVERY

In the presented studies, the laws of the formation of natural stresses in the rock mass are confirmed, which are the sum of gravitational, static tectonic and variable components that have a variable value as a result of uniform periodic volume expansion and contraction of the Earth. The problem of trunk stability is due to the need to solve problems to determine the level of stress-strain state and strength properties in concrete supports. The stress parameters in the lining of the shafts and the monitoring of their changes are determined using a new method for measuring unloading strains. When comparing the stresses obtained experimentally by analytical methods in the concrete support of mine shafts from 2013 to 2019 at experimental test sites in the support having the lengths of bases of 1600 and 70 mm, provided that the number of geoblock ranks at this base is two, a connection with the results of measurements in an array of rocks based on 50 m with an average size of structural blocks of 0.5 m and an investment coefficient of l = 5, which corresponds to three ranks of geoblocks. In practice, it is proposed to use the main identified provisions, namely: the stress state of the mine shaft lining, which is formed as a function of their structural parameters, the full tensor of gravitational tectonic stresses acting in the rock mass at the time of the start of research and time variables, which are determined by natural and analytical methods.

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COMPREHENSIVE ANALYSIS OF THE SHAFT STRUCTURE OF THE DNIPRO METRO

Bridges and tunnels Theory Research Practice ◽

10.15802/bttrp2021/233992 ◽

2021 ◽

pp. 91-98

Author(s):

O. L. TIUTKIN ◽

V. А. MIROSHNYK ◽

I. V. HELETIUK

Keyword(s):

Numerical Analysis ◽

Strain State ◽

Complex Analysis ◽

Comprehensive Analysis ◽

Design Solution ◽

Mine Shaft ◽

Stress Strain ◽

Stress Strain State ◽

Deformed State ◽

Shaft Lining

Purpose. The construction of the Dnipro Metro, which today is characterized by high efficiency and widespread introduction of new technologies, has proved the need for predesign, design and construction work. The purpose of the scientific article is to identify during the complex analysis of the structure of the mine shaft its stress-strain state, which was obtained during the numerical analysis and geodetic monitoring. Methodology. During the complex analysis of the shaft № 16-bis of the Dnipro Metro, prognostic calculations of the stress-strain state were performed. To do this, a finite-element model is built, in which fully reflects the geometric features of the shaft, the load on it and boundary conditions. Part of the comprehensive analysis is geodetic monitoring, which is carried out during the construction of the shaft and during its operation. The works included the measurement of deformations both in the lining of the shafts and in the sections of the mine workings, as well as on the surface near the houses along the route in the area of influence of the working workings. Findings. During the numerical analysis of the structure of the shaft № 16-bis of the Dnipro Metro, displacement and force factors (normal forces and bending moments) were determined. Based on these results, the reinforcement of the elements of the shaft lining (bored pile, cap beam, reinforced concrete ring beam) was selected. The value of the deformed state obtained from the prognostic analysis indicates on the insignificant displacements of the designed structure. During the geodetic monitoring, horizontal and vertical deformations of the № 16-bis shaft lining were recorded, which were caused by the influence of public transport and heavy vehicles. But the values of these deformations reached 1 … 2 mm, which for their effect on buildings and structures is within normal limits. Originality. A comparison of the deformed state obtained during numerical analysis and geodetic monitoring, which proved the high accuracy of the prognostic calculation. Practical value. The results of a comprehensive analysis of the mine shaft of the Dnipro Metro made it possible to carry out a test the design solution and ensure high strength and stability of the lining made of bored piles.

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Microgravity Survey to Detect Voids and Loosening Zones in the Vicinity of the Mine Shaft

Energies ◽

10.3390/en14113021 ◽

2021 ◽

Vol 14 (11) ◽

pp. 3021

Author(s):

Slawomir Porzucek ◽

Monika Loj

Keyword(s):

Rock Mass ◽

Density Distribution ◽

Geophysical Methods ◽

Gravity Anomalies ◽

Vertical Profiles ◽

Mine Shaft ◽

Mining Areas ◽

Shaft Lining ◽

Under Construction ◽

Density Zone

In mining and post-mining areas, the assessment of the risks to the surface and its infrastructure from the opening or closed mine is of the utmost importance; particular attention should be paid to mine shafts. The risks include the occurrence of undetected voids or loosening zones in the rock mass. Their detection makes it possible to prevent their impact on a mine shaft and surface infrastructure. Geophysical methods, and in particular, a microgravity method lend themselves for the detection of changes in the distribution of masses (i.e., the density) due to voids and loosening zones. The paper presents the results of surface microgravity surveys in the vicinity of three mine shafts: under construction, working, and a liquidated one. Based on the gravity anomalies, the density distribution of the rock mass for all three cases was recognized. The properties of the anomalies allowed to determine which of the identified decreased density zones may pose a threat to the surface infrastructure or a mine shaft. The microgravity survey made inside the working mining shaft provided information on the density of rocks outside the shaft lining, regardless of the type of lining. No significant decrease of density was found, which means that there are no larger voids outside the shaft lining. Nevertheless, at a depth of 42 m in running sands layer, the decreasing density zone was located, which should be controlled. Additionally, measurements in two vertical profiles gave the possibility of directional tracking of density changes outside shaft lining. Such changes were observed on three boundaries of geological layers, with two of them being on the boundary of gypsum and other rocks.

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Mechanism of deformation in rock mass surrounding intersection of mine shaft and salt bed

Gornyi Zhurnal ◽

10.17580/gzh.2021.02.02 ◽

2021 ◽

pp. 21-26

Author(s):

V. P. Marysyuk ◽

G. V. Sabyanin ◽

A. A. Andreev ◽

M. A. Vilner

Keyword(s):

Rock Mass ◽

Rock Salt ◽

Observation Station ◽

Mine Shaft ◽

Deformation Stages ◽

Rock Interface ◽

Mechanical Linkage ◽

Shaft Lining ◽

Materials Used ◽

Enclosing Rocks

A bed of rock salt in Komsomolsky Mine occurs in sedimentary strata enclosing cage and skip shafts. When water enters rock salt via underground excavations, boreholes and fractures, rock salt can dissolve and wash out, and voids appear in rock mass. Voids at the lining and rock interface should be eliminated so that never re-appear or grow during shaft operation. Materials used to eliminate voids should ensure stable mechanical linkage both with enclosing rocks and lining. Assessment and analysis of geomechanical processes induced by leaching need monitoring of deformations in a shaft. To this effect, one of the simplest and most informative methods is arrangement of an observation station directly in the shaft lining to measure varying distances between check points. The article briefly describes activities aimed to eliminate voids using different composition grouts. From the analysis of monitoring data, the deformation mechanism is described, and the interaction between different deformation stages and grouting steps is determined. The authors appreciate participations of experts M. P. Sergunin, I. A. Shishkina, A. K. Ustinov, V. V. Tsatskin, V. S. Orlov.

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