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Stability Assessment of Mining Excavations: the Impact of Large Depths

Tadeusz Majcherczyk
Tadeusz Majcherczyk
, 
Zbigniew Niedbalski
Zbigniew Niedbalski
 and 
Łukasz Bednarek
Łukasz Bednarek
   | Oct 24, 2018
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Article Category: Research Article
Published Online: Oct 24, 2018
Page range: 180 - 187
Received: Mar 21, 2018
Accepted: Jul 05, 2018
DOI: https://doi.org/10.2478/sgem-2018-0021
Keywords
© 2018 Tadeusz Majcherczyk et al., published by Sciendo
This work is licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License.

Figure 1

Overall scheme of the measurement station.
Overall scheme of the measurement station.

Figure 2

Distribution of forces in dynamometers – raise gallery Z-VII.
Distribution of forces in dynamometers – raise gallery Z-VII.

Figure 3

Force values in the instrumented rock bolt – airway crosscut W-1.
Force values in the instrumented rock bolt – airway crosscut W-1.

Figure 4

Results of endoscope test in the roof of C-1 cross-cut.
Results of endoscope test in the roof of C-1 cross-cut.

Figure 5

Change of height (A) and width (B) of yielding support arches in relation to nominal dimensions in the panel of airway cross-cut W-1.
Change of height (A) and width (B) of yielding support arches in relation to nominal dimensions in the panel of airway cross-cut W-1.

Figure 6

Dislocation of particular anchors in the roof of S bypass of IIz shaft.
Dislocation of particular anchors in the roof of S bypass of IIz shaft.

Figure 7

Roof separation of S bypass of Ilz shaft.
Roof separation of S bypass of Ilz shaft.

Figure 8

Change of values and orientation of principal stresses in Eastern guideline.
Change of values and orientation of principal stresses in Eastern guideline.

Parameters used in the proposed methodology [19],

ParametersComments
Hkr=Re pen2∗γ$${{H}_{kr}}=\frac{{{R}_{e\,pen}}}{2*\gamma }$$H – depth of excavation site, m;
kr H– critical depth, m;
Rc pen – penetrometric compressive strength, MPa;
HHkr≤1$$\frac{H}{{{H}_{kr}}}\le 1$$γ – specific weight of overlying strata. 0.027, MN/ m3;
WL=∑hi∗ϒi∑hi$${{W}_{L}}=\frac{\sum{{{h}_{i}}*{{\Upsilon }_{i}}}}{\sum{{{h}_{i}}}}$$n – fracture intensiveness coefficient (– );
ls – number of fractures in roof (– );
l– number of strata in roof (–); w
nlslw$$n\frac{{{l}_{s}}}{{{l}_{w}}}$$WL – roof lithology index( – );
hi – thickness of the ith rock layer, m;
W L – n >0ri – reduction coefficient for the ith layer, related to lithology: sandstone – 1.0; siltstone – 0.77; claystone – 0.66; coal – 0.72.

Research results in monitored excavations.

ParametersCross-cut C-1Eastern guidelineAirway cross-cut W-1Raise gallery Z-VIIBypass S of IIz shaft
Depth, m1,2901,0509509501,075
Rc roof, MPaPenetrometer38.140.527.823.351.0
Laboratory67.970.252.956.250.7
RQD, %6.643.714.613.785.4
Number of strata in roof1312936
Number of fractures in roof36277102
Range of crack zone, m6.580.74.71
Maximal force on dynamometers, kN1872222991200
Maximal tensile force in instrumented rock bolt, kN277281150255229
Maximal dislocation of extensometer anchors, mm–6072–1.6
Change of principal stresses, MPa–0.80.611.440.44
Change in height and width of yieldingh–0.010.460.27–
support arches in relation to nominal dimensions, mw0.840.130.220.06–

Variants of possible support loading and deformation of mining excavations [19].

ParametersVariant
IIIIIIIV
HHkr$$\frac{H}{{{H}_{kr}}}$$<1≥1<1≥1
WL – n>0>0≤0≤0
Final resultPossible insignificant loading and deformation of yielding arch supportPossible significant loading of roof bolting supportPossible significant loading and deformation of yielding arch supportPossible significant loading and deformation of yielding arch support and loading of roof bolting support
eISSN:
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Language:
English
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Journal Subjects:
Geosciences, other, Materials Sciences, Composites, Porous Materials, Physics, Mechanics and Fluid Dynamics
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