Investigation of shaft stability and anisotropic deformation in a deep shaft in Idaho, United States

Walton, Gabriel; Kim, E.; Sinha, Sankhaneel; Sturgis, G.; Berberick, D.

doi:10.1016/j.ijrmms.2018.03.017

Cited by 33 publications

(21 citation statements)

References 10 publications

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“…Therefore, the mainly used method in our study is numerical simulation. At present, in shaft research, the applied methods on numerical analysis include the distinct element method and the finite element method [8,9]. Comparing with the results of the finite element method, the accuracy of displacement and stress given by the discrete element method of the paper is more precise and can explicitly simulate the fracture and failure process of an underground excavation [10,11].…”

Section: Introductionmentioning

confidence: 99%

Investigation of Deep Mine Shaft Stability in Alternating Hard and Soft Rock Strata Using Three-Dimensional Numerical Modeling

et al. 2018

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The problem of shaft instability has always been a major difficulty in deep mining practices. The shaft fracture has a high probability of being located near the aquifers and the soft-hard rock contact zone. This paper describes the deformation and stress characteristics of surrounding rock and the shaft lining under the interactive geological conditions under soft and hard rock strata in Anju coal mine, Shandong Province, China. Using the Method of Geological Strength Index (GSI ) and considering the rock-softening characteristics of water, the parameters of rock mass are calibrated. By means of the 3DEC-trigon method, the variation characteristics of surrounding rock and the shaft lining are simulated. After shaft excavation, under the condition of no support, shear failure and tensile failure occur in shallow surrounding rock shafts, and a pressure relief zone is formed. Shear failure is the main destruction mode in deep surrounding rock. Because of the different strengths of the surrounding rock, the deformation of the surrounding rock is significantly different. After the surrounding rock is softened by water absorption, the difference is magnified. The maximum shear stress and plastic zone appear near the interface between soft and hard rock. Under the condition of shaft lining support, uneven deformation of surrounding rock surely leads to nonlinear variation of pressure on the shaft lining. Under the action of an inhomogeneous pressure field, partial shear failure occurs in the shaft lining, and the shear failure area increases after the surrounding rock is softened by water. Because of the nonlinear deformation of the shaft lining, it is easy to produce stress concentration and bending moment near the interface between hard and soft strata. The control methods of advance grouting and pressure relief excavation are proposed to improve the stability of the shaft, and a good effect is gained.Processes 2019, 7, 2 2 of 17 of shaft fractures is mostly located near the aquifers and the contact zone of soft rock interlaced with hard rock. There are mainly five hypotheses on the mechanism of shaft failure of coal mines [3][4][5]: shaft failure by new tectonic movement, the construction of the shaft, groundwater seepage and land subsidence, temperature stress induced under variable temperature, and the vertical additional stress induced by mining and dewatering. However, the mechanism of the failure of a deep shaft in the soft-hard rock interface is still unclear and less studied.Some experts have studied the physical and mechanical properties of alternate rock stratum. A. Yassaghi et al. [6] pointed out that the contact zone rock mass properties were significantly reduced, especially when wet. Through long-term detailed observations of the contact zone in the tunnel, it was proved that the tunnel-wall convergence in the contact zone was 3% higher than that in the normalized tunnel. Wenkai Feng et al. [7] found that deformation failure occurred many times during the Mounigou tunnel construction, and in the soft-h...

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Section: Introductionmentioning

confidence: 99%

Investigation of Deep Mine Shaft Stability in Alternating Hard and Soft Rock Strata Using Three-Dimensional Numerical Modeling

et al. 2018

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“…This observation was repeated in the other extensometers installed as the shaft was deepened. The probable explanation for this observation is shown in Figure 13 (Walton et al 2018). Since the liner was installed 6.6 m behind the installation of the extensometer, the buckling mechanism, with associated foliation dilation had already begun near the shaft surface prior to liner installation.…”

Section: Corporate Mine Operations and Contractor Jointly Work Towamentioning

confidence: 83%

“…For greater detail on this modelling, seeWalton et al (2018) Keynote addresses Ground Support 2019, Sudbury, Canada…”

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confidence: 99%

Ground support from a corporate perspective

Board¹

2019

Proceedings of the Ninth International Symposium on Ground Support in Mining and Underground Construction

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This paper describes the role of the corporate ground control function within Hecla Ltd., a mid-tier US precious metals producer. The position of the ground control function within the corporate structure and the primary responsibility of evaluating and communicating geotechnical risk at company operations and during acquisition is emphasised. A case example is given of how the corporate ground control function was involved in recent ground support issues encountered during the sinking of a 3,000 m deep shaft at the Lucky Friday mine.

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“…In this case, the shaft lining was cast in situ after excavation. Given that the entire excavation cycle takes about 24 hours, it is expected that some of the rock mass deformations behind the lining would have occurred during the early age of the concrete [58]. Wang [59] studied the evolution of concrete's Young's Modulus during its early age and found that the Young's Modulus increases with time until it reaches a relatively stable value (generally accepted to be equivalent to the value on the 28 th day).…”

Section: Numerical Analysis Of Vertical Shaftmentioning

confidence: 99%

Evaluating the Impact of Blast‐Induced Damage on the Rock Load Supported by Liner in Construction of a Deep Shaft: A Case Study of Ventilation Shaft of Micangshan Road Tunnel Project

Fang

Yao

Walton

et al. 2020

Advances in Civil Engineering

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The rock load acting on the lining of an underground excavation is influenced by multiple factors, including rock type, rock mass condition, depth, and construction method. This study focuses on quantifying the magnitude and distribution of the radial loads on the lining of a deep shaft constructed in hard rock by the so-called short-step method. The blasting-induced damage zone (BDZ) around the shaft was characterized using ultrasonic testing and incorporated into the convergence-confinement method (CCM) and 3D numerical analyses to assess the impact of BDZ on rock loading against the liner. The results show that excavation blasting of shafts is an important controlling factor for the degradation of the rock mass, while the orientation and magnitude of the principal stress had a minimal influence on the distribution of blast-induced damage. The analysis shows that increasing the depth of blast damage in the walls can increase the loads acting on the lining, and the shear loads acting on the liner could be significant for shafts sunk by the short-step method in an area with anisotropic in situ stresses.

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Investigation of shaft stability and anisotropic deformation in a deep shaft in Idaho, United States

Cited by 33 publications

References 10 publications

Investigation of Deep Mine Shaft Stability in Alternating Hard and Soft Rock Strata Using Three-Dimensional Numerical Modeling

Investigation of Deep Mine Shaft Stability in Alternating Hard and Soft Rock Strata Using Three-Dimensional Numerical Modeling

Ground support from a corporate perspective

Evaluating the Impact of Blast‐Induced Damage on the Rock Load Supported by Liner in Construction of a Deep Shaft: A Case Study of Ventilation Shaft of Micangshan Road Tunnel Project

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