Asymmetric large deformation of tunnel induced by groundwater in carbonaceous shale

Zhao, Chenyang; Lei, Mingfeng; Jia, Chaojun; Zheng, Keyue; Song, Yintao; Shi, Yanling

doi:10.1007/s10064-022-02757-1

Cited by 17 publications

(1 citation statement)

References 42 publications

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“…Shale has a unique mineral arrangement and bedding structure owing to diagenetic processes such as clay compaction, dehydration, and recrystallization, resulting in significant anisotropy [1][2][3]. Its wide distribution in southwestern China means that it commonly surrounds underground engineering projects such as mines and tunnels [4,5]. Mining processes, such as ore blasting, pillar mining, and backfilling, as well as repeated hydraulic fracturing, reservoir impounding, and dewatering in shale gas mining, all subject the shale to incremental cyclic loading and unloading stages [6][7][8].…”

Section: Introductionmentioning

confidence: 99%

Experimental Research on Anisotropy Characteristics of Shale under Triaxial Incremental Cyclic Loading and Unloading

Cao,

Yan,

Zhang

et al. 2024

Applied Sciences

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Shale is a common rock type that is associated with underground engineering projects, and several important factors, such as bedding structure, confining pressure, and the loading and unloading path, significantly influence the anisotropy of shale. Triaxial monotonic loading tests and triaxial incremental cyclic loading and unloading tests of shale under three kinds of confining pressures and five types of bedding inclination angles (θ) were thus performed to investigate the anisotropy of shale in terms of mechanical behavior, acoustic emission (AE), and energy evolution, and reveal the mechanism by which shale anisotropy is weakened. The results show that (1) the compressive strength and elastic modulus of shale decrease and then increase as the θ increases, and that both σ3 and incremental cyclic loading and unloading reduce the anisotropy in terms of the compressive strength and elastic modulus of shale, with the ratio of plastic strain to total strain reaching its maximum at a θ of 60° during each loading and unloading cycle. (2) The failure modes of shale with θ of 0°, 30°, and 90° under triaxial monotonic loading are similar to the counterparts under triaxial incremental cyclic loading and unloading, while the failure modes of shale with θ of 45° and 60° differ significantly under the two loading conditions, and interestingly, the degree to which the bedding plane participates in shale crack evolution under incremental cyclic loading and unloading is considerably lower than that under triaxial monotonic loading. (3) The cumulative AE count and AE b-value of shale first decrease and then increase as the θ increases, while the Felicity ratio decreases as the number of cycles increases. (4) As the θ increases, the total energy density U0 and the parameter m, which reflects the accumulation rate of elastic energy, first decrease and then increase, with both reaching a minimum at a θ of 60°. (5) The mode by which cyclic loading and unloading leads to failure in shale with a θ of 60° is similar to that at a θ of 0° and is the main mechanism by which shale anisotropy weakening occurs as a result of cyclic loading and unloading. The results provide experimental support and a theoretical basis for safer and more efficient underground engineering projects that involve shale.

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Section: Introductionmentioning

confidence: 99%

Experimental Research on Anisotropy Characteristics of Shale under Triaxial Incremental Cyclic Loading and Unloading

Cao,

Yan,

Zhang

et al. 2024

Applied Sciences

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Research on the bearing capacity characteristics of initial support for horseshoe‐shaped tunnel prefabrication

Xue,

Yan,

et al. 2024

Deep Underground Science and Engineering

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In view of the limited theoretical research on the load model of initial support for horseshoe‐shaped prefabrication, this study focuses on the Luochuan Tunnel on the Xi'an‐Yan'an newly built railway as the research object to explore its load model, load characteristic curve, plastic zone, deformation, and critical thickness. Theoretical research and numerical analysis were conducted. The results indicate that under the same boundary conditions, the ultimate bearing capacity of the prefabricated assembly initial support is higher than that of the shotcrete initial support, resulting in larger ultimate deformation capacity of the prefabricated assembly initial support. Based on numerical calculations, the ultimate deformation and critical thickness of the prefabricated initial lining for single‐ and double‐track railway tunnels are obtained when buried at depths of 200, 500, and 900 m in rock masses of classes III, IV, and V.

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Support Countermeasures for Large Deformation in a Deep Tunnel in Layered Shale with High Geostresses

et al. 2023

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Asymmetric large deformation of tunnel induced by groundwater in carbonaceous shale

Cited by 17 publications

References 42 publications

Experimental Research on Anisotropy Characteristics of Shale under Triaxial Incremental Cyclic Loading and Unloading

Experimental Research on Anisotropy Characteristics of Shale under Triaxial Incremental Cyclic Loading and Unloading

Research on the bearing capacity characteristics of initial support for horseshoe‐shaped tunnel prefabrication

Support Countermeasures for Large Deformation in a Deep Tunnel in Layered Shale with High Geostresses

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