The Analysis of the Deformation and Failure Characteristics of Deep Roadway under the High Stress Force

Red shale is widely distributed among the deep mine areas of Kaiyang Phosphate Mine, which is the biggest underground phosphate mine of China. Because of the effect of various factors, such as high stress, ground water and so on, trackless transport roadways in deep mine areas were difficult to effectively support for a long time by using traditional supporting design methods. To deal with this problem, some innovative works were carried out in this paper. First, mineral composition and microstructure, anisotropic, hydraulic mechanical properties and other mechanical parameters of red shale were tested in a laboratory to reveal its deformation and failure characteristics from the aspect of lithology. Then, some numerical simulation about the failure process of the roadways in layered red shale strata was implemented to investigate the change regulation of stress and strain in the surrounding rock, according to the real rock mechanical parameters and in-situ stress data. Therefore, based on the composite failure law and existing support problems of red shale roadways, some effective methods and techniques were adopted, especially a kind of new wave-type bolt that was used to relieve rock expansion and plastic energy to prevent concentration of stress and excess deformation. The field experiment shows the superiorities in new techniques have been verified and successfully applied to safeguard roadway stability.

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Experimental Test on Nonuniform Deformation in the Tilted Strata of a Deep Coal Mine

Sustainability ◽

10.3390/su132313280 ◽

2021 ◽

Vol 13 (23) ◽

pp. 13280

Author(s):

Hai Wu ◽

Qian Jia ◽

Weijun Wang ◽

Nong Zhong ◽

Yiming Zhao

Keyword(s):

High Stress ◽

Stability Control ◽

Surrounding Rock ◽

Experimental Results ◽

Lower Side ◽

Reinforcement Scheme ◽

Deformation And Failure ◽

True Triaxial ◽

Deep Mine ◽

Deep Coal Mine

Taking a deep-mine horizontal roadway in inclined strata as our research object, the true triaxial simulation technique was used to establish a model of the inclined strata and carry out high-stress triaxial loading experiments. The experimental results show that the deformation of surrounding rock in the roadway presents heterogeneous deformation characteristics in time and space: the deformation of the surrounding rock at different positions of the roadway occurs at different times. In the process of deformation of the surrounding rock, deformation and failure occur at the floor of the roadway first, followed by the lower shoulder-angle of the roadway, and finally the rest of the roadway. The deformation amount in the various areas is different. The floor heave deformation of the roadway floor is the greatest and shows obvious left-right asymmetry. The deformation of the higher side is greater than that of the lower side. The model disassembly shows that the development of cracks in the surrounding rock is characterized by more cracks on the higher side and fewer cracks on the lower side but shows larger cracks across the width. The experimental results of high-stress deformation of the surrounding rock are helpful in the design of supports, the reinforcement scheme, and the parameter optimization of roadways in high-stress-inclined rock, and to improve the stability control of deep high-stress roadways.

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Deformation and failure characteristics of weathered granite under uniaxial compression

AIP Advances ◽

10.1063/1.5113661 ◽

2019 ◽

Vol 9 (7) ◽

pp. 075222 ◽

Cited By ~ 5

Author(s):

Lingfan Zhang ◽

Duoxing Yang ◽

Zhonghui Chen

Keyword(s):

Uniaxial Compression ◽

Failure Characteristics ◽

Deformation And Failure ◽

Weathered Granite

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Experimental study on deformation and failure characteristics of discontinuous prefabricated fractured tuff

Journal of Geophysics and Engineering ◽

10.1093/jge/gxz052 ◽

2019 ◽

Vol 16 (5) ◽

pp. 862-874

Author(s):

Yang Song ◽

Heping Wang ◽

Meng Ren

Keyword(s):

Shear Failure ◽

Failure Process ◽

Dissipated Energy ◽

Uniaxial Compression Test ◽

Tensile Shear ◽

Joint Spacing ◽

Failure Characteristics ◽

Deformation And Failure ◽

Peak Intensity ◽

Dip Angle

Abstract To study more fully the characteristic law of deformation and failure of tuff jointed rock mass of prefabricated parallel discontinuous joint test specimens, the uniaxial compression test was used. The stress–strain curve, peak intensity, deformation parameters, energy characteristics, etc., of the rock test specimens were systematically studied under different combinations of joint dip angle and joint spacing. The research found that: (1) during the failure process of tuff, the peak intensity and elastic modulus followed a U-shaped change pattern and the minimum value was reached when α = 60°; (2) the fracture modes of test specimens with different joint dip angles were different. When α = 30° and 45°, failure characteristics were mixed modes of tensile or tensile shear failure. When α = 60°, failure characteristics were shear. At α = 75°, the failure characteristic was tensile shear failure. (3) The absorbed and dissipated energy of the rock increased nonlinearly at each stage of deformation. (4) We quantified rock energy damage through a correlation between dissipated energy and absorbed energy of the rock in the process of energy evolution, and obtained an evolution of the relationship between the dissipated energy ratio, crack dip angle and crack spacing. Based on different fracture distribution methods and according to the strain equivalence principle, the constitutive equation of the pre-peak rock damage was obtained.

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Research on the deformation and failure mode of rock slope with multiple locking segment failure characteristics

IOP Conference Series Earth and Environmental Science ◽

10.1088/1755-1315/570/6/062002 ◽

2020 ◽

Vol 570 ◽

pp. 062002

Author(s):

QIN Hongnan ◽

MA Haitao ◽

YU Zhengxing

Keyword(s):

Failure Mode ◽

Rock Slope ◽

Failure Characteristics ◽

Deformation And Failure

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Research on Control Mechanism of Surrounding Rock of Deep Gob-Side Entry Retaining

Geofluids ◽

10.1155/2021/2729122 ◽

2021 ◽

Vol 2021 ◽

pp. 1-10

Author(s):

Jianxiong Liu ◽

Jingke Wu ◽

Yun Dong ◽

Yanyan Gao ◽

Jihua Zhang ◽

...

Keyword(s):

Large Deformation ◽

High Stress ◽

Original System ◽

Field Investigation ◽

Surrounding Rock ◽

Eccentric Load ◽

Deformation And Failure ◽

Body Fracture ◽

Stress States ◽

Term Creep

To address the large deformation of the surrounding rock of deep gob-side entry retaining under high stress, lithological characteristics of the surrounding rock and failure model of support body and their evolutionary processes are analyzed through field investigation and theoretical analysis. Failure mechanisms of surrounding rock and the technology to control it are studied systematically. The results show that the causes of the large deformation of the surrounding rock are weak thick mudstones with softening property and water absorption behavior, as well as its fragmentation, dilatancy, and long-term creep during strong disturbance and highly centralized stress states. The cross-section shape of the roadway after deformation and failure of the surrounding rock is obviously asymmetric in both the horizontal and vertical directions. Since the original system supporting the surrounding rock is unable to completely bear the load, each part of the supporting system is destroyed one after the other. The failure sequences of the surrounding rock are as follows: (1) roadway roof fracture in the filling area, (2) filling body fracture under eccentric load, (3) rapid subsidence of the roadway roof, and (4) external crack drum and rib spalling at the solid coal side. Due to this failure sequence, the entire surrounding rock becomes unstable. A partitioned coupling support and a quaternity control technology to support the surrounding rock are proposed, in which the roof of the filling area plays a key role. The technology can improve the overall stability of gob-side entry retaining, prevent support structure instability caused by local failure of the surrounding rock, and ensure the safety and smoothness of roadways.

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Deformation and Failure Characteristics of the Roof in an Unsupported Area during Rapid Driving of Coal Roadway

Shock and Vibration ◽

10.1155/2021/7275334 ◽

2021 ◽

Vol 2021 ◽

pp. 1-13

Author(s):

Sen Yang ◽

Xinzhu Hua ◽

Xiao Liu ◽

Enqian Wang ◽

Chen Li

Keyword(s):

Thin Plate ◽

Simulation Software ◽

Failure Characteristics ◽

Deformation And Failure ◽

Bending Deformation ◽

Coal Roadway ◽

Driving Speed ◽

Support Force ◽

Supporting Force ◽

Influence Degree

In order to study the deflection and failure characteristics of the goaf roof, a mechanical model of the goaf thin plate is established and the deflection expression of the goaf roof is obtained. The results show the following: (1) under the action of single factor, the roof deflection is more sensitive to the interaction of unsupported roof distance and load, but less sensitive to the support force. (2) The influence degree of each factor on the deflection of the thin plate in the unsupported top area is as follows: unsupported roof distance and load interaction > unsupported roof distance and supporting force > supporting force and load. (3) The roof bending deformation is slow when the unsupported roof distance is within 0–2.3 m. When the vacant distance of the roof is more than 2.3 m, the bending deformation of the roof is accelerated. Using FLAC3D numerical simulation software, the distribution of vertical stress and displacement under different space distances is analyzed and the reasonable space distance is 2.0 m. Through the application of 150802 machine roadway in Liuzhuang coal mine, the driving speed of the coal roadway is improved and the monthly footage of coal roadway reaches 506 m.

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Deformation and Failure Characteristics and Control Technology of Roadway Surrounding Rock in Deep Coal Mines

Geofluids ◽

10.1155/2020/8834347 ◽

2020 ◽

Vol 2020 ◽

pp. 1-15 ◽

Cited By ~ 2

Author(s):

Jucai Chang ◽

Dong Li ◽

Tengfei Xie ◽

Wenbao Shi ◽

Kai He

Keyword(s):

High Stress ◽

Development Stage ◽

Surrounding Rock ◽

Deformation And Failure ◽

Deformation Stage ◽

Mining Depth ◽

Floor Heave ◽

Rock Tunnel ◽

Two Sides

With the increase in mining depth, the problem of the floor heave of a roadway is becoming increasingly prominent. Solving this problem for a deep high-stress roadway is the key to ensure safe supply and utilization of coal resources in China. This study investigates the floor heave of a horizontal transportation rock roadway at the depth of 960 m at the Xieyi Mine. A four-way loading simulation test frame similar to the Xieyi Mine was used to reproduce the high-stress environment of a deep roadway by loading different pressures on the roof, floor, and two sides of the roadway. The experimental results show that after the tunnel had been excavated, the surrounding rock failure could be divided into three stages: the initial deformation stage, fissure development stage, and mild deformation stage. The destruction time periods of these stages were 0–0.5 h, 0.5–2 h, and 2–6 h, and the destruction ranges were 0.4 m, 1 m, and 1.5 m, respectively. The amount of roof subsidence, the displacement of the two sides, and the floor heave influence each other, and the range of the bearing ring (5.6 m) of the floor is larger than that of the roof (3.4 m) after the surrounding rock has been damaged. The findings suggest that the floor should be supported first, before the two sides and the roof; then, the support of the key parts (roof and floor corners) should be strengthened. The roof, floor, and two sides are considered for controlling the deformation of the surrounding rock in a coupled trinity support mode. Because of the unfavorable conditions in the area, overexcavation backfill technology was used. The new support was successfully applied during the subsequent construction of the rock tunnel. Based on the long-term monitoring results of the surrounding rock deformation, the floor heave control yielded satisfactory results and maintained the long-term stability of the roadway. Therefore, this study can serve as a reference for preventing floor heave in similar high-stress roadways in the future.

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Numerical Prediction of Residual Deformation and Failure for Powder Bed Fusion Additive Manufacturing of Metal Parts

Journal of Mechanics ◽

10.1017/jmech.2020.30 ◽

2020 ◽

Vol 36 (5) ◽

pp. 623-636

Author(s):

D.D. Lyu ◽

W. Hu ◽

B. Ren ◽

X.F. Pan ◽

C. T. Wu

Keyword(s):

Additive Manufacturing ◽

Process Simulation ◽

Residual Deformation ◽

Numerical Approach ◽

Small Scale ◽

Powder Bed Fusion ◽

Failure Characteristics ◽

Deformation And Failure ◽

Powder Bed ◽

Inherent Strain Method

ABSTRACTResidual deformation and failure are two critical issues in powder bed fusion (PBF) additive manufacturing (AM) of metal products. Residual deformation caused by the non-uniform residual stress distribution dramatically affects the quality of AM product and can result in catastrophic failure in operation. Therefore, the development of an effective numerical approach to predict residual deformation and failure characteristics of AM product is always a major concern in industrial applications.In this paper, a numerical approach in predicting residual distortion, stress and failure in AM products is presented. The conventional inherent strain method used in welding process is modified to consider the specific characteristic of AM process, such as the influences of reheating and scanning pattern. This approach consists of three simulation steps including a detailed process simulation in small-scale, a onetime static mechanical finite element analysis in part-scale, and a material failure analysis. First, the inherent strains are calculated from a thermo-mechanical process simulation in small-scale, which considers AM process parameters, such as laser power, scanning speed and path. The physical state in deposited materials including powder, liquid and solid states are taken into account in the simulation by specifying the solidus and liquidus temperature and corresponding material properties. Then the inherent strains are applied layer by layer to the part-scale simulation, where the residual distortion and stress can be predicted efficiently. Finally, a Lagrange particle method is utilized to study the failure characteristics of AM products. Numerical examples are studied to investigate the effectiveness and applicability of present approach.

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