TY - JOUR
T1 - Discontinuum–Equivalent Continuum Analysis of the Stability of Tunnels in a Deep Coal Mine Using the Distinct Element Method
AU - Shreedharan, Srisharan
AU - Kulatilake, Pinnaduwa H.S.W.
N1 - Funding Information:
The research was funded by the US Centers for Disease Control and Prevention under the Contract No. 200-2011-39886. The authors would like to thank Xiezhuang Coal Mine and Dr. Zhengxing Yu and Professor Fuxing Jiang of University of Science and Technology Beijing for providing laboratory and field geological and geotechnical data for this research. The authors further thank the Xiezhuang Coal Mine for providing the encouragement to conduct this research and to publish the research findings.
Publisher Copyright:
© 2015, Springer-Verlag Wien.
PY - 2016/5/1
Y1 - 2016/5/1
N2 - An imperative task for successful underground mining is to ensure the stability of underground structures. This is more so for deep excavations which may be under significantly high stresses. In this manuscript, we present stability studies on two tunnels, a horseshoe-shaped and an inverted arch-shaped tunnel, in a deep coal mine in China, performed using the 3DEC distinct element code. The rock mass mechanical property values for the tunnel shapes have been estimated through a back-analysis procedure using available field deformation data. The back-analysis has been carried out through a pseudo-time dependent support installation routine which incorporates the effect of time through a stress-relaxation mechanism. The back-analysis indicates that the rock mass cohesion, tensile strength, uniaxial compressive strength, and elastic modulus values are about 35–45 % of the corresponding intact rock property values. Additionally, the importance of incorporating stress relaxation before support installation has been illustrated through the increased support factor of safety and reduced grout failures. The calibrated models have been analyzed for different supported and unsupported cases to estimate the significance and adequacy of the current supports being used in the mine and to suggest a possible optimization. The effects of supports have been demonstrated using deformations and yield zones around the tunnels, and average factors of safety and grout failures of the supports. The use of longer supports and floor bolting has provided greater stability for the rock masses around the tunnels. Finally, a comparison between the two differently shaped tunnels establishes that the inverted arch tunnel may be more efficient in reducing roof sag and floor heave for the existing geo-mining conditions.
AB - An imperative task for successful underground mining is to ensure the stability of underground structures. This is more so for deep excavations which may be under significantly high stresses. In this manuscript, we present stability studies on two tunnels, a horseshoe-shaped and an inverted arch-shaped tunnel, in a deep coal mine in China, performed using the 3DEC distinct element code. The rock mass mechanical property values for the tunnel shapes have been estimated through a back-analysis procedure using available field deformation data. The back-analysis has been carried out through a pseudo-time dependent support installation routine which incorporates the effect of time through a stress-relaxation mechanism. The back-analysis indicates that the rock mass cohesion, tensile strength, uniaxial compressive strength, and elastic modulus values are about 35–45 % of the corresponding intact rock property values. Additionally, the importance of incorporating stress relaxation before support installation has been illustrated through the increased support factor of safety and reduced grout failures. The calibrated models have been analyzed for different supported and unsupported cases to estimate the significance and adequacy of the current supports being used in the mine and to suggest a possible optimization. The effects of supports have been demonstrated using deformations and yield zones around the tunnels, and average factors of safety and grout failures of the supports. The use of longer supports and floor bolting has provided greater stability for the rock masses around the tunnels. Finally, a comparison between the two differently shaped tunnels establishes that the inverted arch tunnel may be more efficient in reducing roof sag and floor heave for the existing geo-mining conditions.
KW - 3DEC
KW - Back-analysis
KW - Deep coal mine
KW - Numerical modeling
KW - Support optimization
KW - Tunnel stability
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U2 - 10.1007/s00603-015-0885-9
DO - 10.1007/s00603-015-0885-9
M3 - Article
AN - SCOPUS:84946781553
SN - 0723-2632
VL - 49
SP - 1903
EP - 1922
JO - Rock Mechanics and Rock Engineering
JF - Rock Mechanics and Rock Engineering
IS - 5
ER -