A case study on large deformation failure mechanism of deep soft rock roadway in Xin'An coal mine, China

Yang, Sheng‐Qi; Chen, Miao; Jing, Hongwen; Chen, Kun-Fu; Meng, Bo

doi:10.1016/j.enggeo.2016.12.012

Cited by 365 publications

(161 citation statements)

References 31 publications

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“…(3DEC) is one of the most commonly used DEM software programs, and precisely reflects the stress and strain characteristics in 3D space. In the 3DEC simulation, to overcome the defects of only allowing fracture development along predefined discontinuities, the 3DEC-trigon method approach is used to research shaft stability [12][13][14]. In this thesis, 3DEC-trigon method is applied to simulate the mine shaft stability in soft-hard rock based on a case study at AN JU mine shaft.…”

Section: The Engineering Statusmentioning

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: The Engineering Statusmentioning

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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“…Fig. 1 Rheological failures of laneway [4] The axisymmetric deformation analysis of the rock around a circular tunnel is a classic problem. The ground responses of elasto-perfectly-plastic, elasto-brittle-plastic and strain-softening have been studied.…”

Section: Introductionmentioning

confidence: 99%

Analytical solution of circular tunnel in elastic-viscoplastic rock mass

Wang

Jiang

Zhang

et al. 2019

Lat. Am. j. solids struct.

Self Cite

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This paper deals with a deep circular tunnel excavated in infinite homogeneous and isotropic elastoviscoplastic rock mass subjected to a hydrostatic initial stresses. The tunnel is divided into the initial plastic, viscoplastic, and elastic zones. By combining the generalized Bingham model with Mohr-Coulomb yield criteria, analytical solutions of the circular tunnel are derived with the consideration of non-associated flow rule and elasto-viscoplasticity. The initial plastic zone is defined as the instantaneous change of rock mass excavation. Based on the initial plastic zone, the stresses in viscoplastic zone are transferred to the deep surrounding rock with time due to the initial earth stresses. The results are compared with the elastic-brittle solution at static conditions, and the solutions of this paper are validated. Moreover, the presented results shows that the stress and displacement of the surrounding rock varies with time, and the solutions can be obtained at different instants of time.

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“…In Chinese coal mines, 70‐80 percent of the annual roadway excavations are developed under the high‐stress conditions which can be attributed to the geological abnormalities, the large burial depth, the strong abutment stresses, or the combination of those factors . The high‐stress conditions often cause large deformation of the roadways, and in some cases, the convergence rate of roadway surfaces may reach up to 100 mm/d; therefore, significant efforts are routinely required to reconstruct the roadways . As a result, the cost of longwall mining is significantly increased and the production of coal is greatly restricted …”

Section: Introductionmentioning

confidence: 99%

“…[1][2][3] The high-stress conditions often cause large deformation of the roadways, and in some cases, the convergence rate of roadway surfaces may reach up to 100 mm/d; therefore, significant efforts are routinely required to reconstruct the roadways. 4,5 As a result, the cost of longwall mining is significantly increased and the production of coal is greatly restricted. 1,6 Researchers have developed some techniques to improve the bearing capacities of the surrounding rocks and reduce the convergence of roadways developed under high-stress environment.…”

Section: Introductionmentioning

confidence: 99%

Depressurizing boreholes for mitigating large deformation of the main entry

Wang

Zheng

Shen

et al. 2019

Energy Science & Engineering

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The main entries in longwall coal mine frequently encounter large deformation, depending on the stress environment. Depressurizing boreholes are applicable to reduce the large deformation; however, it is difficult to determine the proper parameters (diameter and spacing) for an effective implementation. This study aims to propose feasible design criteria for the quantification of those parameters. We first developed a rigorous numerical model, for a roadway in Zhangshuanglou coal mine, using the rock mechanical properties determined from extensive laboratory measurements and analyses. We then investigated the dependency of the stress transfer and roadway deformation on the ratio of borehole diameter and spacing (D/R and D/I). The symbols of D, R, and I represented the diameter, row spacing, and interspacing of the boreholes, respectively. We found that (a) D/R has to be between 1:6 and 1:2; and (b) D/I has to be between 1:6 and 1:4, for sufficient depressurization in the surrounding rocks. The optimized borehole diameter and spacing parameters were applied in the field where the deformation of roadway was significantly reduced. Finally, we proposed a criterion to determine those parameters of depressurization boreholes for application in other geological and mining conditions.

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A case study on large deformation failure mechanism of deep soft rock roadway in Xin'An coal mine, China

Cited by 365 publications

References 31 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

Analytical solution of circular tunnel in elastic-viscoplastic rock mass

Depressurizing boreholes for mitigating large deformation of the main entry

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