Large deformation of tunnels in longwall coal mines

Wang, Meng; Zheng, Dongjie; Niu, Shuangjian; Li, Wenfeng

doi:10.1007/s12665-019-8044-3

Cited by 20 publications

(9 citation statements)

References 35 publications

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“…Coal resources account for 70% and 60% of the primary energy production and consumption structure, respectively, and they have always been the main energy source of China. In recent years, the mining scale and intensity of coal mines have gradually increased with the prosperity of coal production each year, and many large and super‐large section chambers and chamber groups have emerged . The cluster distribution of super‐large section chambers makes the interaction between the chambers fierce, and it is very easy to cause dynamic accidents such as roof fall and rib spalling.…”

Section: Introductionmentioning

confidence: 99%

Numerical investigation of failure evolution for the surrounding rock of a super‐large section chamber group in a deep coal mine

Tan

Fan

Liu

et al. 2019

Energy Science & Engineering

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The stability control of surrounding rock for a large or super‐large section chamber group is a difficult technical problem in deep mining conditions, and this stability control has become one of the most important factors restricting the safety of a large‐scale coal mine. Based on the in‐site geological conditions of a super‐large section chamber group that functions for a coal gangues separation system in the Longgu Coal Mine, we first researched the stress, deformation, and failure characteristics of the in‐site chamber group surrounding rocks by using the FLAC3D software. Simulation results showed that the maximum vertical stress, deformation, and failure range of the surrounding rock for a super‐large section chamber group are larger than those of an ordinary section chamber. In addition, the roof subsidence and the plastic zone radius at the intersection are obviously larger than that of other parts, which increase by approximately 50.8% and 44.4%, respectively. Therefore, the chamber group intersection should be taken as the key area for surrounding rock control. Then, the influences of two key parameters of the chamber group, spacing and angle, were researched in detail to help in the design of the chamber group. Results show that when the chamber spacing is 80 m, the interaction begins to occur. When the angle is 70°, the stress of the surrounding rock and roof subsidence reach the minimum. Thus, the optimum chamber group parameters are determined to be a spacing of 80 m and an angle of 70°. Finally, from the perspective of chamber group stability, the optimal chamber group parameters can better meet the normal use for the super‐large section chamber group. This research provides a reference for the design of a super‐large section chamber group under the same or similar conditions and provides a strategy for controlling the surrounding rock.

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Section: Introductionmentioning

confidence: 99%

Numerical investigation of failure evolution for the surrounding rock of a super‐large section chamber group in a deep coal mine

Tan

Fan

Liu

et al. 2019

Energy Science & Engineering

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“…We use the strain‐softening Mohr‐Coulomb model to quantify the peak and the postpeak properties of the rocks. As being documented in many studies, this model is characterized by the cohesion and friction angle for peak strengths and by the alternation of both properties for the postpeak behavior. The difficulty of using this model lies in quantifying the relations between rock properties (cohesion and friction angle) and the accumulation of the plastic strains .…”

Section: Laboratory Tests and Development Of The Numerical Modelmentioning

confidence: 99%

“…Finally, we observed the exponential degradation (Equations and ) of the cohesion and friction angle as the shear plastic strain was increased. Details of the triaxial tests can be found in our previous work

c = 10.5952 e^{- γ_{p} true/ 0.00441} + 2.7157 R^{2} = 0.8168

φ = 12.2587 e^{- γ_{p} true/ 0.00241} + 25.2349 R^{2} = 0.9105

where

c

is the cohesion of the intact core;

φ

is the friction angle of the intact core; and

γ_{p}

is the shear plastic strain of the intact core.…”

Section: Laboratory Tests and Development Of The Numerical Modelmentioning

confidence: 99%

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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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“…To verify the results of the empirical analyses, FLAC3D (Ding and Liu, 2018;Wang et al, 2019;Yang et al, 2019;Zhu et al, 2018) was used to calculate the deformation and depth of the plastic zones around caverns, owing to the staged excavation and rock support. Plane strain analysis was used because of the large ratio of length to cross-section dimension of the underground caverns.…”

Section: Numerical Analysismentioning

confidence: 99%

Stability analysis of underground water-sealed oil storage caverns in China：A case study

Xingdong

Deng

Zhang

2020

Energy Exploration & Exploitation

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The stability of underground water-sealed oil storage caverns is of great importance for safe excavation and operation. To analyze the scope of the failure zone and underground cavern stability accurately, a new method was developed that integrates the rock tunneling quality index Q-system and stability graph method with 3D laser scanning and numerical simulation. The point cloud data were obtained by 3D laser scanning, and the cavern model was built by using DIMINE software, which directly shows the 3D shape of the cavern. The rock mass physical and mechanical parameters and the corresponding stability coefficients were obtained based on Q-system and stability graph method. The plastic zone distribution and deformation characteristics of surrounding rock were analyzed through numerical simulation. Then, the corresponding relationship between caving zone and plastic zone was determined by comparing the numerical simulation results with the 3D laser scanning contour. The new method provides a reliable way to analyze the stability of the underground water-sealed oil storage cavern and also will helpful to design or optimize the subsequent support.

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Large deformation of tunnels in longwall coal mines

Cited by 20 publications

References 35 publications

Numerical investigation of failure evolution for the surrounding rock of a super‐large section chamber group in a deep coal mine

Numerical investigation of failure evolution for the surrounding rock of a super‐large section chamber group in a deep coal mine

Depressurizing boreholes for mitigating large deformation of the main entry

Stability analysis of underground water-sealed oil storage caverns in China：A case study

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