scholarly journals Evaluation of the Mechanical Instability of Mining Roadway Overburden: Research and Applications

Energies ◽  
2019 ◽  
Vol 12 (22) ◽  
pp. 4265 ◽  
Author(s):  
Housheng Jia ◽  
Kun Pan ◽  
Shaowei Liu ◽  
Bo Peng ◽  
Kai Fan
Keyword(s):  
Plastic Zone ◽  
Tensile Failure ◽  
Mechanical Instability ◽  
Support Design ◽  
Deformation And Failure ◽  
Plastic Failure ◽  
Wide Range ◽  
Shallow Strata ◽  
Middle Strata ◽  
Deep Strata

Under the superposed action of the primary rock stress and the mining stress, the compound roof of a roadway will have irregular plastic failure zone with greater depth, resulting in a wide range of non-uniform deformations and roof failures. Mastering the deformation and failure characteristics of this roof is essentially to recognize the development of the plastic zone of a compound roof. In this paper, the on-site roof detection method is mainly adopted to arrange a large number of boreholes for visualization and the deep displacement monitoring with the high-density points. Combined with numerical simulations, the rupture development characteristics and deformation mechanisms of the compound roof are revealed. The results show that the magnitude and direction of the principal stress of surrounding rock in a mining roadway are constantly changing, and the penetrating phenomenon will occur during the plastic zone expansion process. The order of the compound roof rupture as follows: shallow strata plastic failure, deep strata penetrating plastic failure and middle strata rupture. Severe roof deformation is mainly caused by plastic failure, and the strong deformation pressure caused by deep strata penetration plastic failure can easily lead to tensile failure and rupture in the middle strata. According to the plastic zone penetration development of the compound roof, the hierarchical support design led by the long-extension bolt is carried out on the test roadway. The monitoring results show that the roof is controlled well. The research results can provide a reference for the control of compound roofs in mining roadways.

scholarly journals Research on Deep-Site Failure Mechanism of High-Steep Slope under Active Fault Creeping Dislocation

2021 ◽  
Vol 2021 ◽  
pp. 1-12
Author(s):  
Yang Liu ◽  
Kaiwen Zhang ◽  
Denghang Tian ◽  
Liming Qu ◽  
Yang Liu
Keyword(s):  
Plastic Zone ◽  
Principal Stress ◽  
Fracture Zone ◽  
Exponential Growth ◽  
Maximum Principal Stress ◽  
Tensile Failure ◽  
Lower Envelope ◽  
Envelope Curve ◽  
Plastic Failure ◽  
Deep Site

The reverse thrust in the deep site causes the upward propagation of stress and displacement in the overlying soil. The displacement field around the fault zone is maximum. As the spatial location becomes shallower, the soil displacement gradually becomes smaller. The deformation of the overlying soil is mainly affected by the vertical dislocation of the fracture zone. The monitoring curve showed no abrupt change value, indicating that the top surface of soil did not rupture, and only the influence of fault on the displacement transfer of the top surface of the soil. When a creeping dislocation occurs in the bottom fracture zone, the maximum principal stress of the upper boundary of the deep site is dominated by compressive stress. The maximum principal stress of the soil on both sides of the fracture zone has a maximum value, and the soil on the right side of the fracture zone has a significant compression effect. The maximum principal stress monitoring curve varies greatly, indicating the plastic failure development of soil, which is the same as the research results of the plastic failure zone in the following paper. When the bottom fracture zone starts to move, the plastic zone first appears at the junction area between the front end of the bottom fracture zone and the overlying soil. As the amount of dislocation of the fracture zone increases, the plastic zone continues to extend into the inner soil. The left and right sides of the fracture zone show tensile failure and compression failure, respectively. The development of the upper envelope curve in the plastic zone of the overlying soil satisfies the Boltzmann equation with a first-order exponential growth, while the development of the lower envelope curve satisfies the Gauss equation with a second-order exponential growth. The development curve equation of the plastic zone is verified according to the residual figures of the fitting result and the correlation parameters.

Research on the Influence by Different Dip Angles Faults of the Damage Height of Superincumbent Stratum

2014 ◽  
Vol 675-677 ◽  
pp. 1421-1424 ◽  
Author(s):  
Zhen Li Fan
Keyword(s):  
Plastic Zone ◽  
Coal Seam ◽  
Small Angle ◽  
High Angle ◽  
Fractured Zone ◽  
Fault Surface ◽  
Influence Area ◽  
Wide Range

For the issue of fault impact on the height of water-flowing fractured zone, the study worked out several damage heights of superincumbent stratum under the influence of different dip angles faults. The research shows that small angle fault influence area is apt to develop a wide range of the plastic zone,and the water-flowing fractured zone of high-angle fault influence area is apt to increase along the fault surface and breakover the aquifers of coal seam roof and floor.

scholarly journals Research on Failure Characteristics of Concrete Three-Point Bending Beams with Preexisting Cracks in Different Positions Based on Numerical Simulation

Geofluids ◽  
2021 ◽  
Vol 2021 ◽  
pp. 1-8
Author(s):  
Liuqun Zhao ◽  
Li Zheng ◽  
Hui Qin ◽  
Tiesuo Geng ◽  
Yonggang Tan ◽  
...  
Keyword(s):  
Acoustic Emission ◽  
Bearing Capacity ◽  
Failure Modes ◽  
Failure Process ◽  
Engineering Application ◽  
Tensile Failure ◽  
Engineering Structures ◽  
Failure Characteristics ◽  
Three Point Bending ◽  
Wide Range

Concrete three-point bending beams with preexisting cracks are widely used to study the growth process of I-II mixed mode cracks. Studying the failure characteristics of preexisting cracks at different locations on concrete three-point bending beams not only has important scientific significance but also has a wide range of engineering application backgrounds in the safety assessment of engineering structures. In this paper, through several numerical experiments, the influence of preexisting cracks at different positions on the failure characteristics of concrete three-point bending beams is studied, and three typical failure modes are obtained. The failure process of the specimens with three typical failure modes is discussed in detail, and it is pointed out that the crack failure mode is tensile failure. The change trends of bearing capacity, acoustic emission quantity, and acoustic emission energy of three typical failure modes are analyzed. The maximum bearing capacity, the maximum acoustic emission quantity, and energy of three failure modes of concrete three-point bending beams generally show an increasing trend.

Numerical Simulation for Geotechnical Material of Mine Stope by Mechanics and Deformation Performance

2012 ◽  
Vol 472-475 ◽  
pp. 1899-1902
Author(s):  
Xiong Gang Xie ◽  
Shi Qing Xu ◽  
Zhang Yin Dai
Keyword(s):  
Numerical Simulation ◽  
Rock Mass ◽  
Numerical Calculation ◽  
Plastic Zone ◽  
Mechanical Method ◽  
Deformation And Failure ◽  
The Real ◽  
Mechanics Performance ◽  
Real Practice ◽  
Calculation Software

This paper is focused on the mechanics and deformation performance of mine stope after excavation. The deformation performance is described by the settlement of stope roof, and the mechanics performance is described by the plastic zone of rock mass surrounding stope. The numerical calculation software FLAC3D is used to simulate the deformation and failure situation of the rock mass surrounding complicated large underground stope. In the calculation, the excavation procedure for the stope is simulated. The mechanical method has been adopted to establish the analysis on the stope stability, the results are in accordance with the actual situations, and can help to more accurately predict location of failure. The conclusion can give some guidance for the real practice.

scholarly journals Contemporary Treatment Strategy for Spinal Metastasis: The “LMNOP” System

2011 ◽  
Vol 38 (3) ◽  
pp. 396-403 ◽  
Author(s):  
Gillian R. Paton ◽  
Evan Frangou ◽  
Daryl R. Fourney
Keyword(s):  
Spinal Metastasis ◽  
Scoring Systems ◽  
Management Plan ◽  
Classification Systems ◽  
Mechanical Instability ◽  
Key Factors ◽  
Management Options ◽  
Prior Therapy ◽  
Wide Range ◽  
Choice Of Treatment

The choice of treatment for spinal metastasis is complex because (1) it depends on several inter-related clinical and radiologic factors, and (2) a wide range of management options has evolved in recent years. While radiation therapy and surgery remain the cornerstones of treatment, radiosurgery and percutaneous vertebral augmentation have also established a role. Classification systems have been developed to aid in the decision-making process, and each has different strengths and weaknesses. The comprehensive scoring systems developed to date provide an estimate of life expectancy, but do not provide much advice on the choice of treatment. We propose a new decision model that describes the key factors in formulating the management plan, while recognizing that the care of each patient remains highly individualized. The system also incorporates the latest changes in technology. The LMNOP system evaluates the number of spinal Levels involved and the Location of disease in the spine (L), Mechanical instability (M), Neurology (N), Oncology (O), Patient fitness, Prognosis and response to Prior therapy (P).

scholarly journals Analytical Solution of Tunnel Surrounding Rock for Stress and Displacement Based on Lade–Duncan Criterion

2018 ◽  
Vol 2018 ◽  
pp. 1-7 ◽  
Author(s):  
MingZheng Zhu ◽  
Yugui Yang ◽  
Feng Gao ◽  
Juan Liu
Keyword(s):  
Internal Friction ◽  
Plastic Zone ◽  
Yield Criterion ◽  
Surrounding Rock ◽  
Rock Stress ◽  
Deformation And Failure ◽  
Displacement Based ◽  
The Stability ◽  
Coulomb Criterion

The deformation and failure of tunnel surrounding rock is the result of tunnel excavation disturbance and rock stress release. When the local stress of surrounding rock exceeds the elastic limit of rock mass, the plastic analysis of surrounding rock must be carried out to judge the stability of tunnel. In this study, the Lade–Duncan yield criterion is used to calculate the analytic solutions for the surrounding rock in a tunnel, and the radius and displacement of the plastic zone are deduced using an equilibrium equation. The plastic zone radius and displacement based on Lade–Duncan criterion and Mohr–Coulomb criterion were compared by using single-factor analysis method under the different internal friction angles, in situ stresses, and support resistances. The results show that the solutions of the radius and displacement of plastic zone calculated by the Lade–Duncan criterion are close to those of Mohr–Coulomb criterion under the high internal friction angle and support resistance or low in situ rock stress; however, the radius and displacement of the plastic zone calculated by the Lade–Duncan criterion are larger under normal circumstances, and the Lade–Duncan criterion is more applicable to the stability analysis of the surrounding rock in a tunnel.

Characterizing Competencies for Human-Centered Design

2016 ◽  
Author(s):  
Julia Kramer ◽  
Alice M. Agogino ◽  
Celeste Roschuni
Keyword(s):  
Core Competencies ◽  
Future Research ◽  
Support Design ◽  
Human Centered Design ◽  
Future Design ◽  
Core Set ◽  
Starting Point ◽  
Wide Range ◽  
Successful Design ◽  
Research Interviews

Employees and employers alike increasingly value human-centered design, as it can drive innovation across a wide range of industries. With the growing interest in understanding human-centered design processes as they apply in different professions, there is a rising need to recognize the specific competencies necessary to perform these jobs well. Though there is a body of research on how people discover, create, and use design methods, there is a lack of understanding of what core competencies are necessary for people to apply these methods. Previous interactions with target users of theDesignExchange, an interactive community-driven portal to support design researchers and practitioners, have demonstrated a desire for increased awareness of the competencies required for employability and for successful design practice. This paper reports on a portion of an expansive competency-finding project aimed at identifying the core set of competencies that human-centered design practitioners need and employers seek. In this paper, we present our lists of cultivated mindsets, specialized disciplinary skills, contextualized tasks, and basic skills in human-centered design. These lists represent a first pass at identifying the essential and underlying competencies a practicing or aspiring human-centered designer must have in order to perform their current or future design tasks. The work we present in this paper serves as a preliminary starting point for future research interviews with design practitioners and employers, as we seek to understand human-centered design competencies.

scholarly journals Low Velocity Surface Fracture Patterns in Brittle Material: A Newly Evidenced Mechanical Instability

2012 ◽  
Vol 706-709 ◽  
pp. 920-924 ◽  
Author(s):  
M.L. Hattali ◽  
J. Barés ◽  
L. Ponson ◽  
D. Bonamy
Keyword(s):  
High Speed ◽  
Glassy Polymers ◽  
Mechanical Instability ◽  
Low Velocity ◽  
Loading Mode ◽  
Fracture Patterns ◽  
Velocity Surface ◽  
Wide Range ◽  
Tension Loading ◽  
Very High

The occurrence of various instabilities at very high speed is well known to occur in brittle fracture and significant advances have recently been obtained in the understanding of their origin. On the other hand, low speed brittle crack propagation under pure tension loading (mode I) is usually thought to yield smooth crack surfaces. The experimental investigation reported here questions this statement. Steady cracks were driven in brittle glassy polymers (PolyMethyl Methacrylate - PMMA) using a wedge-splitting geometry over a wide range of low velocities (10-9-10-1m/s). Three distinct patterns can be observed on the post-mortem fracture surfaces as crack velocity decreases: perfectly smooth at the highest speed, regularly fragmented at intermediate speed and macroscopically rough at the lowest speed. The transition between the two latter is reminiscent of chaotic [email protected],[email protected],[email protected],[email protected],

scholarly journals Occurrence Mechanism of Roof-Fall Accidents in Large-Section Coal Seam Roadways and Related Support Design for Bayangaole Coal Mine, China

2018 ◽  
Vol 2018 ◽  
pp. 1-17 ◽  
Author(s):  
Shitan Gu ◽  
Bangyou Jiang ◽  
Gensheng Wang ◽  
Huabin Dai ◽  
Mingpeng Zhang
Keyword(s):  
Coal Seam ◽  
Coal Mine ◽  
Large Scale ◽  
Control Method ◽  
Tensile Failure ◽  
Large Section ◽  
Support Design ◽  
Roof Fall ◽  
Occurrence Mechanism ◽  
Fall Accidents

This study focused on large-scale roof-fall accidents occurred in large-section coal seam roadways of Bayangaole Coal Mine, Inner Mongolia, China, and investigated the occurrence mechanism of roof-fall and the related supporting control method in detail. Firstly, the fracture characteristics of the surrounding rocks on the roadway roof were measured using a stratum detector. The results showed that the roadway roof underwent the most severe failure with a maximum deformation of 3.53 m; the bedding separation and fracture zones were distributed at irregular intervals. Accordingly, the entire stratum was separated into several thin sublayers, significantly reducing the stability of roof. In addition, the roof medium grained sandstone of roadway is water-rich strata, and water aggravates the damage of roof. Next, the mechanism of the occurrence of roof-fall accidents in the roadway was elucidated in detail. The following three reasons are mainly attributed to the occurrence of roof-fall accidents: (i) effects of mining-induced stress and tectonic stress, (ii) existence of equipment cavern on the side of roadway, and (iii) unreasonable support parameters. On that basis, a new supporting design is proposed, including a more reasonable arrangement of anchor cables and bolts, bolts with full-length anchorage which are applicable in cracked and water-rich roadway, high-strength anchor cables, and crisscrossed steel bands. Moreover, high pretightening force was applied. Finally, a field test was performed, and the mining-induced roof displacement and stress on anchor cable (bolt) were monitored in the test section. The maximum roof displacements at the two monitoring sections were 143 mm and 204 mm, respectively, far smaller than the roadway’s allowable deformation. Moreover, the stress on roof anchor cables (bolts) was normal, and no anchorage-dragging and tensile failure phenomena were observed. The monitoring data indicated that the new supporting design was remarkable on the control of large-section coal seam roadway roof deformation.

scholarly journals Deformation and Failure Mechanism of Surrounding Rock in Mining-Influenced Roadway and the Control Technology

2021 ◽  
Vol 2021 ◽  
pp. 1-14
Author(s):  
Jicheng Feng ◽  
Shuaifeng Yin ◽  
Zhiheng Cheng ◽  
Jianjun Shi ◽  
Haoyu Shi ◽  
...  
Keyword(s):  
Plastic Zone ◽  
Failure Mechanism ◽  
Principal Stress ◽  
Pressure Ratio ◽  
Confining Pressure ◽  
Simulation Software ◽  
Surrounding Rock ◽  
Morphologic Change ◽  
Deformation And Failure ◽  
Implicit Equation

Aiming at the problem of surrounding rock deformation and failure of mining roadway and its control, a mechanical model of the circular roadway under the mining environment is established, and the implicit equation of the plastic zone boundary is derived. By analyzing the morphologic evolution law of the surrounding rock plastic zone in the mining roadway, the key factors affecting the morphologic change of the plastic zone are obtained, that is, the magnitude and direction of principal stress. The influence law of the magnitude and direction of principal stress on the plastic zone of the mining roadway is analyzed by using numerical simulation software, and the deformation and failure mechanism of surrounding rock of the mining roadway is revealed. The results showed that the size and morphology of the plastic zone were closely related to the confining pressure ratio (η). Taking the boundary of η valuing 1, the larger or smaller η value was, the more serious the deformation and failure of surrounding rock would be; the morphology of the plastic zone changed with the deflection of the principal stress, with the location of the maximum plastic zone influenced by the principal stress direction. For the surrounding rock control in the mining-influenced roadway, it is advised to take the following methods: firstly, it is necessary to consider how to reduce or remove the influence of mining on surrounding rock, improve the stress environment of surrounding rock, and reduce the failure depth of the plastic zone, so as to better maintain the roadway. Secondly, in view of the deformation and failure characteristics of the mining roadway, the fractional support method of “yielding first and then resisting” should be adopted, which applies the cable supplement support after mining instead of the one-off high-strength support during roadway excavation, so as to control the malignant expansion of the surrounding rock plastic zone and prevent roof falling accidents.

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