Abstract
The combined action of mining disturbance and floor-bearing water pressure causes the primary meso-cracks of the coal seam floor to be damaged and expanded to varying degrees. Moreover, the compressive strength of the rock is reduced to varying degrees, resulting in the development of meso-cracks in the floor. Fissures in the macroscopic scale are formed, developed, and connected. In this work, a mesoscopic crack model of different dip angles of the floor stratum was established according to Griffith’s theory. Scanning electron microscopy (SEM) was used to scan and monitor the coal seam floor rock samples before and after mining. Using a rock rheometer, saturated and dry rock samples were subjected to triaxial compression tests under various confining pressures. FLAC3D software was used to simulate the production of fissures in macro-floor rock formations under the conditions of limited water mining. The results of the study demonstrated that microscopic natural fractures existed in the floor strata, with horizontal and oblique crack angles. Micro-cracks with horizontal dip and oblique angles appeared under the operation of mining disturbance and constrained water pressure, and cracks with varying dip angles appeared at the end of the original crack, according to SEM observations. The rock strength deteriorated to varied degrees as a result of the impact of floor water. The compressive strength of rock mass decreased in the saturated state, the rock mass displayed nonlinear failure in the dry state, and the compressive strength of the rock sample increased as the confining pressure increased. The failure depth and range of the floor increased with increase in the bearing water pressure of the floor during the simulated excavation operation.
Highlights
-
A mesoscopic crack model of different dip angles of the floor stratum was established.
-
The SEM observation of coal seam floor strata was carried out.
-
The rock strength deteriorated to varied degrees as a result of the impact of floor water.
-
The numerical simulation of the failure of coal seam floor is carried out.
Similar content being viewed by others
Data Availability
The data used to support the findings of this study are available from the corresponding author upon request.
Abbreviations
- FLAC:
-
Fast Lagrangian analysis of continua
- UDEC:
-
Universal distinct element code
- BPNN:
-
Back-propagation neural network
- SVM:
-
Support vector machine
- GA:
-
Genetic algorithm
- GIS:
-
Geographic Information System
- x :
-
Fracture direction
- y :
-
Vertical fracture direction
- t :
-
Time
- a :
-
The semi-major axis of the ellipse,
- b :
-
The semi-minor axis of the ellipse,
- α :
-
The eccentric angle about the x-axis.
- σ 1 , σ 3 :
-
Maximum principal stress and minimum principal stress
- σ x , σ y :
-
X-direction stress and Y-direction stress
- σ z :
-
Peak intensity
- θ :
-
Angle between long axis of fine fracture and maximum principal stress
- x 0, y 0 :
-
Initial position in X-direction and Initial position in Y-direction
- i x y :
-
Shear stress in XY direction
- m :
-
Axial ratio of ellipse
- σ q :
-
Tangential stress at any point
- σ q max :
-
Maximum shear stress in different fracture orientations
- σ q sm.m :
-
Extreme value of shear stress
- Rt :
-
Uniaxial compressive strength
- P w :
-
Confined water pressure
- σ':
-
Actual compressive strength
References
Akbardoost J, Ayatollahi MR, Aliha MRM, Pavier MJ, Smith DJ (2014) Size-dependent fracture behavior of Guiting limestone under mixed mode loading. Int J Rock Mechan Mining Sci 71:369–380. https://doi.org/10.1016/j.ijrmms.2014.07.019
Aliha MRM (2014) Ayatollahi MR (2014) Rock fracture toughness study using cracked chevron notched Brazilian disc specimen under pure modes I and II loading–A statistical approach. Theoretical and Applied Fracture Mechanics 69:17–25. https://doi.org/10.1016/j.tafmec.2013.11.008
Aliha MRM, Ayatollahi MR (2013) Two-parameter fracture analysis of SCB rock specimen under mixed mode loading. Eng Fract Mechan 103:115–123. https://doi.org/10.1016/j.engfracmech.2012.09.021
Aliha MRM, Bahmani A (2017) Rock fracture toughness study under mixed mode I/III loading. Rock Mechan Rock Eng 50(7):1739–1751. https://doi.org/10.1007/s00603-017-1201-7
Aliha MRM, Ayatollahi MR, Smith DJ, Pavier MJ (2010) Geometry and size effects on fracture trajectory in a limestone rock under mixed mode loading. Eng Fract Mechan 77(11):2200–2212. https://doi.org/10.1016/j.engfracmech.2010.03.009
Aliha MRM, Sistaninia M, Smith DJ, Pavier MJ, Ayatollahi MR (2012) Geometry effects and statistical analysis of mode I fracture in guiting limestone. Int J Rock Mechan Mining Sci 51:128–135. https://doi.org/10.1016/j.ijrmms.2012a.01.017
Aliha MRM, Ayatollahi MR, Akbardoost J (2012) Typical upper bound–lower bound mixed mode fracture resistance envelopes for rock material. Rock Mechan Rock Eng 45(1):65–74. https://doi.org/10.1007/s00603-011-0167-0
Aliha MRM, Hosseinpour GR, Ayatollahi MR (2013) Application of cracked triangular specimen subjected to three-point bending for investigating fracture behavior of rock materials. Rock mechanics and rock engineering 46(5):1023–1034. https://doi.org/10.1007/s00603-012-0325-z
Aliha MRM, Mahdavi E, Ayatollahi MR (2017) The influence of specimen type on tensile fracture toughness of rock materials. Pure Appl Geophys 174(3):1237–1253. https://doi.org/10.1007/s00024-016-1458-x
Aliha MRM, Berto F, Mousavi A (2017) Razavi, SMJ (2017b) On the applicability of ASED criterion for predicting mixed mode I+ II fracture toughness results of a rock material. Theoret Appl Fract Mechan 92:198–204. https://doi.org/10.1016/j.tafmec.2017b.07.022
Aliha MRM, Mahdavi E, Ayatollahi MR (2017) The influence of specimen type on tensile fracture toughness of rock materials. Pure Appl Geophys 174(3):1237–1253. https://doi.org/10.1007/s00024-016-1458-x
Aliha MRM, Mahdavi E, Ayatollahi MR (2018) Statistical analysis of rock fracture toughness data obtained from different chevron notched and straight cracked mode I specimens. Rock Mechan Rock Eng 51(7):2095–2114. https://doi.org/10.1007/s00603-018-1454-9
Ayatollahi MR (2007) Aliha MRM (2007) Fracture toughness study for a brittle rock subjected to mixed mode I/II loading. Int J Rock Mech Min Sci 44(4):617–624. https://doi.org/10.1016/j.ijrmms.2006.10.001
Ayatollahi MR, Aliha MRM (2008) On the use of Brazilian disc specimen for calculating mixed mode I-II fracture toughness of rock materials. Eng Fract Mech 75(16):4631–4641. https://doi.org/10.1016/j.engfracmech.2008.06.018
Bahmani A, Nemati S (2021) Fracture resistance of railway ballast rock under tensile and tear loads. Eng Solid Mechan 9(3):271–280. https://doi.org/10.5267/j.esm.2021.3.003
Bahmani A, Farahmand F, Janbaz MR, Darbandi AH, Ghesmati-Kucheki H, Aliha MRM (2021) On the comparison of two mixed-mode I+ III fracture test specimens. Eng Fract Mechan 241:107434. https://doi.org/10.1016/j.engfracmech.2020.107434
Bidadi J, Akbardoost J, Aliha MRM (2020) Thickness effect on the mode III fracture resistance and fracture path of rock using ENDB specimens. Fatigue & Fracture of Engineering Materials & Structures 43(2):277–291. https://doi.org/10.1111/ffe.13121
Chen JT, Zhao JH, Zhang SC, Zhang Y, Yang F, Li M (2020) An experimental and analytical research on the evolution of mining cracks in deep floor rock mass. Pure Appl Geophys 177(11):5325–5348. https://doi.org/10.1007/s00024-020-02550-9
Du H, Dai F, Wei M, Li A, Yan ZL (2021) Dynamic compression–shear response and failure criterion of rocks with hydrostatic confining pressure: an experimental investigation. Rock Mech Rock Eng 54(2):955–971
Han LJ, He YN, Zhang HQ (2016) Study of rock splitting failure based on griffith strength theory. International Journal of Rock Mechanics and Mining Sciences 83:116–121. https://doi.org/10.1016/j.ijrmms.2015.12.011
Hu YB, Li WP, Qiqing Wang QQ, Liu SL, Wang ZK (2019) Study on failure depth of coal seam floor in deep mining. Environm Earth Sci 78(2):54–60. https://doi.org/10.1007/s12665-019-8731-0
Isheyskiy V, Marinin M (2017) Determination of rock mass weakening coefficient after blasting in various fracture zones. Eng Solid Mechan 5(3):199–204. https://doi.org/10.5267/j.esm.2017.4.001
Kang YS, Liu QS, Liu XY, Huang S (2014) Theoretical and numerical studies of crack initiation and propagation in rock masses under freezing pressure and far-field stress. J Rock Mechan Geotechn Eng 6(5):466–476. https://doi.org/10.1016/j.jrmge.2014.05.004
Li ZH, Zhai CZ, Xie H, Yang FG (2016) Similar Simulation Test for Breakage Law of Working Face Floor in Coal Mining Above Aquifer. J Comput Theoret Nanosci 13(7):4230–4235. https://doi.org/10.1166/jctn.2016.5273
Liu L, Li H, Li X, Wu D, Zhang GK (2021) Underlying mechanisms of crack initiation for granitic rocks containing a single pre-existing flaw: Insights from digital image correlation (DIC) analysis. Rock Mech Rock Eng 54(2):857–873
Ma D, Duan HY, Cai X, Li ZH, Li Q, Zhang Q (2018) A global optimization-based method for the prediction of water inrush hazard from mining floor. Water 10(11):1618–1618. https://doi.org/10.3390/w10111618
Ma K, Wang LJ, Peng YL, Long LJ, Wang SJ, Chen T (2020) Permeability characteristics of fractured rock mass: a case study of the Dongjiahe coal mine. Geomat Nat Haz Risk 11(1):1724–1742. https://doi.org/10.1080/19475705.2020.1811403
Mirsayar MM, Razmi A, Aliha MRM (2018) Berto F (2018) EMTSN criterion for evaluating mixed mode I/II crack propagation in rock materials. Eng Fract Mechan 190:186–197. https://doi.org/10.1016/j.engfracmech.2017.12.014
Qu XY, Qiu M, Liu JH, Niu ZC, Wu XS (2019) Prediction of maximal water bursting discharge from coal seam floor based on multiple nonlinear regression analysis. Arabian J Geosci 12(18):1–20. https://doi.org/10.1007/s12517-019-4748-7
Razavi SMJ, Aliha MRM, Berto F (2018) Application of an average strain energy density criterion to obtain the mixed mode fracture load of granite rock tested with the cracked asymmetric four-point bend specimens. Theoret Appl Fract Mechan 97:419–425. https://doi.org/10.1016/j.tafmec.2017.07.004
Shi LQ, Qiu M, Wang Y, Qu XY, Liu TH (2019) Evaluation of water inrush from underlying aquifers by using a modified water-inrush coefficient model and water-inrush index model: a case study in Feicheng coalfield, China. Hydrogeol J 27(6):2105–2119. https://doi.org/10.1007/s10040-019-01985-2
Sicsic P, Marigo JJ (2013) From gradient damage laws to Griffith’s theory of crack propagation. J Elasticity 113(1):55–74. https://doi.org/10.1007/s10659-012-9410-5
Sun J, Miao XX (2017) Water-isolating capacity of an inclined coal seam floor based on the theory of water-resistant key strata. Mine Water Environm 36(2):310–322. https://doi.org/10.1007/s10230-017-0428-6
Sun WB, Zhang SC, Guo WJ, Liu WT (2017) Physical simulation of high-pressure water inrush through the floor of a deep mine. Mine Water Environm 36(4):542–549. https://doi.org/10.1007/s10230-017-0443-7
Wang GJ, Yang TF, Wang GZ, Peng JY (2011) Research on Failure mechanism of floor aquifuge based on" Down Three Zones" Theory. Zhongzhou Coal 11(2011):4–5+24. https: //doi:CNKI:SUN:ZZMT.0.2011–11–004.11.(In Chinese)
Wang JS, Yao DX, Huang H (2018) Critical criterion and physical simulation research on progressive ascending water inrush in hidden faults of coal mines. China Coal Soc 43: 2014–2020 https://doi.org/10.13225/j.cnki.jccs.2017.1252.
Wu Q, Liu YZ, Wu HX, Zeng YF (2017) Assessment of floor water inrush with vulnerability index method: application in Malan Coal Mine of Shanxi Province, China. Quarterly J Eng Geol Hydrogeol 50(2):169–178. https://doi.org/10.1144/qjegh2016-105
Xu Y, Dai F, Zhao T, Xu NW, Liu W (2016) Fracture Toughness Determination of Cracked Chevron Notched Brazilian Disc Rock Specimen via Griffith Energy Criterion Incorporating Realistic Fracture Profiles. Rock Mechan Rock Eng 49(8):3083–3093. https://doi.org/10.1007/s00603-016-0978-0
Xu YC, Zhang EM, Luo YQ, Zhao L, Yi K (2020) Mechanism of water inrush and controlling techniques for fault-traversing roadways with floor heave above highly confined aquifers. Mine Water Environm 39(2):320–330. https://doi.org/10.1007/s10230-020-00670-1
Yang DZ (2012) Editorial for special issue on Fracture mechanics: from Griffith theory, numerical modelling to applications. Fatigue Fract Eng Mater Str 35(8):693–694. https://doi.org/10.1111/j.1460-2695.2012.01675.x
Yang BB, Sui WH, Duan LH (2017) Risk assessment of water inrush in an underground coal mine based on GIS and fuzzy set theory. Mine Water Environm 36(4):617–627. https://doi.org/10.1007/s10230-017-0457-1
Acknowledgements
This research was funded by the National Natural science Foundation of China (grant 51874192), the Natural Science Foundation of Shandong Province (grant ZR2019MEE084), State Key Laboratory of Strata Intelligent Control and Green Mining Co-founded by Shandong Province and the Ministry of science and Technology Open Fund (grant SICGM202103) and the SDUST Research Fund (grant 2018TDJH102). We would like to thank MogoEdit (https://www.mogoedit.com) for its English editing during the preparation of this manuscript.
Author information
Authors and Affiliations
Corresponding author
Ethics declarations
Conflict of Interest
The authors declare that they have no conflicts of interest.
Additional information
Publisher's Note
Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.
Rights and permissions
About this article
Cite this article
Liu, W., Pang, L., Wu, Q. et al. Research on the Damage Evolution of the Confined Water Floor Cracks in the Deep Stope Based on the Macro–Micro Study. Rock Mech Rock Eng 55, 5029–5045 (2022). https://doi.org/10.1007/s00603-022-02917-5
Received:
Accepted:
Published:
Issue Date:
DOI: https://doi.org/10.1007/s00603-022-02917-5