Hydration-induced fractures in shale with silt layers: A perspective on slope stability

Abstract

This study investigates the phenomenon of slope failure in shale, particularly in the context of heavy rainfall events. Despite the critical role that water plays in influencing the stability of shale slopes, the effects of hydrological conditions on their structural integrity remain inadequately understood. To address this gap, the research integrates field observations with controlled laboratory experiments aimed at elucidating the relationship between water infiltration and shale stability under varying boundary conditions. Shale blocks without silt layers (SNSL) and those with horizontal (H-SSL) and vertical (V-SSL) silt layers were considered. Vertical tensile fractures were observed in SNSL blocks, while H-SSL blocks displayed horizontal fractures along the silt layers, particularly at failed corners in the BFC. Fractures along the silt layers and diagonal fractures were more pronounced under the BCC. V-SSL blocks exhibited the formation of vertical rock columns along the silt layers, which were more common in the BFC. Inclined small fractures were commonly observed under the BCC. In a wet environment, shale demonstrates high responsiveness, and its behavior in the presence of water is complex. Water interaction with shale blocks leads to fracture formation, influenced by the clay matrix and silt layers. The introduction of water alters the clay matrix, resulting in tensile fractures. Silt layers act as weak planes, facilitating fracture propagation. Notably, shale is vulnerable under the BCC, with increased vulnerability under the BFC, particularly due to silt layers with outward-facing dips. The study recommends constructing retaining walls and applying polymers to enhance local and regional stability, mitigating the risks associated with slope failure.

Keywords

Heavy-rainfall / Slope failure / Shale stability / Hydration-induced fractures / Silt layers / Road cutting

CRediT authorship contribution statement

AKM Badrul Alam: Writing - review & editing, Writing - original draft, Methodology, Investigation, Funding acquisition, Conceptualization. Yoshiaki Fujii: Writing - review & editing. Nahid Hasan: Writing - review & editing, Data curation. Torin Chakma: Writing - review & editing.

Declaration of competing interest

The authors declare that there have no conflicts of interest.

Acknowledgments

We wish to express our profound appreciation to the technical staff in the laboratory for their indispensable contributions and steadfast support throughout the duration of our research endeavors. It is funded by R&D, Military Institute of Science and Technology (MIST).

References

[1] P. Amiotte Suchet, J.L. Probst, W. Ludwig, Worldwide distribution of continental rock lithology: implications for the atmospheric/soil CO2 uptake by continental weathering and alkalinity river transport to the oceans, Glob. Biogeochem. Cycles 17 (2) ( 2003). Jun.

[2] A. Jordan, H. Oldrich, S.T. D, B.A.K. Oso, Washington, landslide of March 22, 2014: dynamic analysis, J. Geotech. Geoenviron. Eng. 143 (9) ( 2017) 05017005.

[3] L.E. Mark, G.D. Peter, Chapter 4 landslide and slope stability hazard in the UK, Geolog. Soc. London, Eng. Geol. Special Publ. 29 (1) ( 2020) 81-162.

[4] Bangladesh Water Development Board, Rainfall data.

[5] B. Department of Disaster Management, History of landslides in Bangladesh in 21st century. http://www.adrc.asia/latest_disaster.php?NationCode=50&Lang=en&Mode=country&NationNum=13. (Accessed 31 October 2023).

[6] L. Baoping, Laboratory study on effect of hydration to shale mechanics, J. Geomechanics (1999) [Online]. Available: https://api.semanticscholar.org/CorpusID:130938620.

[7] L. Ping, C. Drilling, Theoretical simulation and experimental evaluation of the effect of hydration on the shale rock strength, Drill. Prod. Technol. ( 2010) [Online]. Available:

[8] W. Dong, J. Tian, Q. Chen, P. Wang, T. Han, Y. Zhai, D. Jiang, Relationship between shale hydration and shale collapse, ACS Omega 11 (46) ( 2022) 42524-42536, 7.

[9] Bin Qian, Juhui Zhu, Hai Yang, Liang Xing, Congbin Yin, Shi Xiaozhi, Li Deqi, Li Junlong, Hui Fang, Experiments on shale reservoirs plugs hydration, Petrol. Explor. Dev. 44 (4) ( 2017) 615-621.

[10] Y.T. Duan, X. Li, B. Zheng, B.C. Yang, Investigation on hydration and deformation characteristics of shale using X-ray computed tomography, Geofluids ( 2022).

[11] Y. Hai, S. Xiaozhi, C. Yin, X. Liang, J. Zhao, L. Junlong, Z. Juhui, G. Zhoumei, W. Zhou, R. Li, Brazilian tensile failure characteristics of marine shale under the hydration effect of different fluids, Nat. Gas. Ind. B 7 ( 2020) 639-647.

[12] Y. Li, L. Xu, J. Chen, W. Zhang, D. Elsworth, Hydration of transitional shale and evolution of physical properties constrained by concurrent NMR and acoustic observations, Energy Fuels 37 (1) ( 2023) 7809-7822.

[13] Y. Wang, R. Liu, H. Ji, S. Li, L. Yu, X. Feng, Correlating mechanical properties to fractal dimensions of shales under uniaxial compression tests, Environ. Earth Sci. 82 (1) ( 2022) 2.

[14] F. Zhang, T. Yang, Stability and probabilistic assessment of a large asymmetric bedding slope with a weak interlayer, Environ. Sci. Pollut. Control Ser. 30 (49) ( 2023) 107811-107826.

[15] B.R. Jones, L.B. Brouwers, W.D. Van Tonder, M.A. Dippenaar, Assessing geotechnical centrifuge modelling in addressing variably saturated flow in soil and fractured rock, Environ. Sci. Pollut. Control Ser. 24 (15) ( 2017) 13203-13223.

[16] Y. Wang, R. Liu, H. Ji, S. Li, L. Yu, X. Feng, Correlating mechanical properties to fractal dimensions of shales under uniaxial compression tests, Environ. Earth Sci. 82 (1) ( 2022) 2.

[17] K. Gu, Z. Ning, Fractal dimension changes of shale pore structure and influence on mechanical properties, relative permeability under different hydration degree, Environ. Earth Sci. 82 (7) ( 2023) 189.

[18] A. Sharma, R. Ramkrishnan, Parametric optimization and multi-regression analysis for soil nailing using numerical approaches, Geotech. Geol. Eng. 38 ( 2020) 3505-3523.

[19] M.A. Islam, M.S. Islam, A.A. Jeet, A geotechnical investigation of 2017 Chattogram landslides, Geosciences 11 (8) ( 2021) 337.

[20] A.K.M.B. Alam, Y. Fujii, N. Islam, M.A. Rahman, A. Al Hasan, M.A. Hasan, A. Al Hasan, M.A. Hasan, Stability of shale at a slope, in: IOP Conference Series: Earth and Environmental Science, IOP Publishing Ltd, Oct. 2021.

[21] Harold P. Klug, Leroy E. Alexander, X-Ray Diffraction Procedures: for Polycrystalline and Amorphous Materials, second ed., second ed., Wiley, 1974.

[22] P.K. Sims, Sarah Chadima, R.F. Biek, Industrial Minerals, Today and Tomorrow; the Raw Materials to Build the Upper Midwest, 1992.

[23] A.B. Alam, Y. Fujii, N.H. Dipu, T. Chakma, P. Neogi, A.W. Ullah, R.A. Abdullah, Potential of carboxymethyl cellulose solution to increase the shale stability, Sci. Rep. 13 (1) ( 2023) 17388.

[24] ISRM, ISRM suggested methods, in: E.T. Brown (Ed.), Rock Characterization, Testing and Monitoring, Pergamon Press, London, 1981.

[25] ASTM, Standard test method for slake and durability of shales and similar weak rocks (D4644), Annu. Book ASTM Stand. 4 ( 1990) 8.

[26] J.A. Franklin, R. Chandra, The slake-durability test, Int. J. Rock Mech. Min. Sci. Geomech. Abstracts 9 (3) ( 1972) 325-328.

[27] L. Bailey, M. Keall, A. Audibert, J. Lecourtier, Effect of clay/polymer interactions on shale stabilization during drilling, Langmuir 10 (5) ( 1994) 1544-1549.

[28] Civan Faruk, Mineralogy and mineral sensitivity of petroleum-bearing formations 1, in: Reservoir Formation Damage, 1999.