scholarly journals Experiment on Mine Ground Pressure of Stiff Coal-Pillar Entry Retaining under the Activation Condition of Hard Roof

2018 ◽  
Vol 2018 ◽  
pp. 1-11 ◽  
Author(s):  
Wen-long Shen ◽  
Wen-bing Guo ◽  
Hua Nan ◽  
Chun Wang ◽  
Yi Tan ◽  
...  
Keyword(s):  
Mechanical Behavior ◽  
Physical Model ◽  
Dynamic Stress ◽  
Coal Pillar ◽  
Vibration Signal ◽  
Monitoring Systems ◽  
Hard Roof ◽  
Ground Pressure ◽  
Floor Heave ◽  
Rock Strata

In mining excavation, the retained entry with stiff coal pillar is situated in the strong mine ground pressure. Influenced by mining abutment stress and dynamic stress (the vibration signal) induced from the hard roof activation, the retained entry may be subjected to roof separation, supporting body failure, severe floor heave, and even roof collapse. Based on a 2D physical model, an experimental method with plane-stress conditions was used to simulate the mechanical behavior of the rock strata during mining. In this experiment, three monitoring systems were adopted to reveal the characteristics of the strong mine ground pressure in the stiff coal-pillar entry retaining. The results show that the hard roof undergoes bending down, fracture, and caving activation successively until it is able to support overlying loads. The abutment stress which is induced from the loading transfer in stiff coal pillar is larger than that in other rocks around the retained entry in amplification, and overlying loads above the worked-out area have a loading effect on the unworked-out area. When the hard roof is situated in the activation state, the dynamic stress is generated from the hard roof activation, which is verified by the great saltation of acoustic emission signals. The results of mining ground pressure in the physical model can clearly illustrate the mechanical behavior of the rock around the retained entry with stiff coal pillar.

scholarly journals Assessment of the Piezoelectric Response of an Epoxy Resin/SbSINanowires Composite Filling FDM Printed Grid

Materials ◽  
2020 ◽  
Vol 13 (22) ◽  
pp. 5281
Author(s):  
Mateusz Kozioł ◽  
Piotr Szperlich ◽  
Bartłomiej Toroń ◽  
Piotr Olesik ◽  
Marcin Jesionek
Keyword(s):  
Dynamic Stress ◽  
Piezoelectric Effect ◽  
Wide Spectrum ◽  
Piezoelectric Response ◽  
Monitoring Systems ◽  
Grid Structure ◽  
Voltage Signal ◽  
Antimony Sulfoiodide ◽  
Deposition Modeling ◽  
Applied Design

This paper shows a piezoelectric response from an innovative sensor obtained by casting epoxy-SbSI (antimony sulfoiodide) nanowires nanocomposite to a grid structure printed using a fuse deposition modeling (FDM) method. The grid is shown to be a support structure for the nanocomposite. The applied design approach prospectively enables the formation of sensors with a wide spectrum of shapes and a wide applicability. The voltage signal obtained as a result of the piezoelectric effect reached 1.5V and 0.5V under a maximum static stress of 8.5 MPa and under a maximum dynamic stress of 22.3 kPa, respectively. These values are sufficient for potential application in sensor systems. The effect of a systematic increase in the voltage signal with subsequent cycles was also observed, which similarly allows the use of these sensors in monitoring systems for structures exposed to unfavorable cyclical loads. The obtained results also show that the piezoelectric signal improves with increase in strain rate.

scholarly journals A Comprehensive Review of the Mechanical Behavior of Suspension Bridge Tunnel-Type Anchorage

2019 ◽  
Vol 2019 ◽  
pp. 1-19 ◽  
Author(s):  
Yafeng Han ◽  
Xinrong Liu ◽  
Ning Wei ◽  
Dongliang Li ◽  
Zhiyun Deng ◽  
...  
Keyword(s):  
Mechanical Behavior ◽  
Failure Modes ◽  
Load Transfer ◽  
Mechanical Response ◽  
Soft Rock ◽  
Suspension Bridge ◽  
Development Trend ◽  
Factors Affecting ◽  
Research Results ◽  
Rock Strata

The recent surge of interest towards the mechanical response of rock mass produced by tunnel-type anchorage (TTA) has generated a handful of theories and an array of empirical explorations on the topic. However, none of these have attempted to arrange the existing achievements in a systematic way. The present work puts forward an integrative framework laid out over three levels of explanation and practical approach, mechanical behavior, and calculation method of the ultimate pullout force to compare and integrate the existing findings in a meaningful way. First, it reviews the application of TTA in China and analyzes its future development trend. Then, it summarizes the research results of TTA in terms of load transfer characteristics, deformation characteristics, failure modes, and calculation of ultimate uplift resistance. Finally, it introduces four field model tests in soft rock (mainly mudstone formations), and some research results are obtained. Furthermore, it compares the mechanical behavior of TTA in hard rock strata and soft rock strata, highlighting the main factors affecting the stability of TTA in soft rock formation. This paper proposes a series of focused topics for future investigation that would allow deconstruction of the drivers and constraints of the development of TTA.

scholarly journals Study on the Fracture Law of Inclined Hard Roof and Surrounding Rock Control of Mining Roadway in Longwall Mining Face

Energies ◽  
2020 ◽  
Vol 13 (20) ◽  
pp. 5344
Author(s):  
Feng Cui ◽  
Shuai Dong ◽  
Xingping Lai ◽  
Jianqiang Chen ◽  
Chong Jia ◽  
...  
Keyword(s):  
Energy Release ◽  
Longwall Mining ◽  
Coal Pillar ◽  
High Energy ◽  
Mechanical Analysis ◽  
Engineering Practice ◽  
Analysis Model ◽  
Hard Roof ◽  
Working Face ◽  
The Stability

In the inclination direction, the fracture law of a longwall face roof is very important for roadway control. Based on the W1123 working face mining of Kuangou coal mine, the roof structure, stress and energy characteristics of W1123 were studied by using mechanical analysis, model testing and engineering practice. The results show that when the width of W1123 is less than 162 m, the roof forms a rock beam structure in the inclined direction, the floor pressure is lower, the energy and frequency of microseismic (MS) events are at a low level, and the stability of the section coal pillar is better. When the width of W1123 increases to 172 m, the roof breaks along the inclined direction, forming a double-hinged structure, the floor pressure is increased, and the frequency and energy of MS events also increases. The roof gathers elastic energy release, and combined with the MS energy release speed it can be considered that the stability of the section coal pillar is better. As the width of W1123 increases to 184 m, the roof in the inclined direction breaks again, forming a multi-hinged stress arch structure, and the floor pressure increases again. MS high-energy events occur frequently, and are not conducive to the stability of the section coal pillar. Finally, through engineering practice we verified the stability of the section coal pillar when the width of W1123 was 172 m, which provides a basis for determining the width of the working face and section coal pillar under similar conditions.

scholarly journals Mining-Induced Failure Criteria of Interactional Hard Roof Structures: A Case Study

Energies ◽  
2019 ◽  
Vol 12 (15) ◽  
pp. 3016 ◽  
Author(s):  
Shen ◽  
Wang ◽  
Cao ◽  
Su ◽  
Nan ◽  
...  
Keyword(s):  
Mechanical Behavior ◽  
Longwall Mining ◽  
Underground Mining ◽  
Failure Criteria ◽  
Normal Operation ◽  
Analysis Model ◽  
Plane Stress Condition ◽  
Field Case ◽  
Hard Roof ◽  
Soft Interlayer

Due to the additional abutment stress, interactional hard roof structures (IHRS) affect the normal operation of the coal production system in underground mining. The movement of IHRS may result in security problems, such as the failure of supporting body, large deformation, and even roof caving for nearby openings. According to the physical configuration and loading conditions of IHRS in a simple two-dimensional physical model under the plane stress condition, mining-induced failure criteria were proposed and validated by the mechanical behavior of IHRS in a mechanical analysis model. The results indicate that IHRS, consisting of three interactional parts—the lower key structure, the middle soft interlayer, and the upper key structure—are governed by the additional abutment stress induced by the longwall mining working face. The fracture of the upper key structure in IHRS can be explained as follows: Due to the crushing failure, lower key structure, and middle soft interlayer yield, the action force between the upper and lower key structures vanishes, resulting in fracture of the upper key structure in IHRS. In a field case, when additional abutment stress reaches 7.37 MPa, the energy of 2.35 × 105 J is generated by the fracture of the upper key structure in IHRS. Under the same geological and engineering conditions, the energy generated by IHRS is much larger than that generated by a single hard roof. The mining-induced failure criteria are successfully applied in a field case. The in-situ mechanical behavior of the openings nearby IHRS under the mining abutment stress can be clearly explained by the proposed criteria.

Key Technologies for Ground Pressure Monitoring System

2014 ◽  
Vol 568-570 ◽  
pp. 370-373
Author(s):  
Hui Jun Liang ◽  
Bi Tao Li
Keyword(s):  
Monitoring System ◽  
Power Supply ◽  
Monitoring Systems ◽  
Pressure Monitoring ◽  
Ground Pressure ◽  
Displacement Sensors ◽  
Key Technologies

Ground pressure monitoring systems have been installed in many mines; there are several methods which have been used in this monitoring system, in this paper the key technologies are elaborated about ground pressure monitoring, which includes displacement sensors, the choice of power supply, the arrange of network, the serial-Ethernet convertor and human-machine interface’s design.

Improving Performance of an Artificial Neural Network Based Gearbox Fault Diagnosis System

2010 ◽  
Author(s):  
Ali Hajnayeb ◽  
Ahmad Ghasemloonia ◽  
Siamak Esmaeelzadeh Khadem ◽  
Mohammad Hasan Moradi
Keyword(s):  
Fault Diagnosis ◽  
Condition Monitoring ◽  
Vibration Signal ◽  
Monitoring Systems ◽  
Test Rig ◽  
Tooth Gear ◽  
Different Types ◽  
Condition Monitoring Systems ◽  
Artificial Neural ◽  
Detection Speed

The automatic vibration monitoring methods of gears and gearboxes due to their extensive applications in industry are improving. Hence, their vibration signal and its derived features, has been an interesting topic for researchers in this field. On the other hand, optimizing the number of vibration signal features used in the detection and diagnosis process is crucial for increasing the fault detection speed of automatic condition monitoring systems. In this paper, a system based on multiple layer perceptron artificial neural networks (MLP ANNs) is designed to diagnose different types of fault in a gearbox. Using a feature selection method, the system is optimized through eliminating unimportant features of vibration signals. This method is based on a simple and fast sensitivity evaluation process, which results in a considerable estimation, despite its simplicity. Consequently, the system’s speed increases, while the classification error decreases or remains constant in some other cases. An experimental test rig data set is used to verify the effectiveness and accuracy of the mentioned method. Four different types of data which are generated through the test rig setup are: no fault condition, 5% fault (5% eroded tooth) gear, 20% eroded tooth gear and the broken tooth gear. The results verify that eliminating some input features of gear vibration signal, using this method, will increase the accuracy and detection speed of gear fault diagnosis methods. The improved systems with fewer input features and higher precision, facilitates the development of online automatic condition monitoring systems.

Utilizing the Purified Orbit Curve Technical in AP1000 NPP Turbine Diagnosis (Monitoring) Systems

2013 ◽  
Author(s):  
Peidi Han
Keyword(s):  
Power Plant ◽  
Nuclear Power Plant ◽  
Nuclear Power ◽  
Field Data ◽  
Spline Interpolation ◽  
Vibration Signal ◽  
Monitoring Systems ◽  
Diagnosis Accuracy ◽  
Turbine Shaft ◽  
Filter Prototype

To improve the diagnosis accuracy and self-adaptability of steam turbine diagnosis systems in AP1000 NPP, this article attempts to apply a new method which unifies digital filter and stimulant filter into the filter processing of turbine Shaft vibration signal in Nuclear Power Plant. According to the process of power plant field data guideline, 4-level Butterworth filter prototype is used to resolve noise influence on original vibration signal. Supported by Matlab ANN Tools and Delphi, this study uses “spline” interpolation in the Process of orbit curve; with an ideal smooth effect achieved after compliance, this practice is proved that it can enhance the recognition effect of in Sanmen AP1000 Nuclear Power Plant TDM(Turbine Diagnosis Systems) monitoring functions.

scholarly journals A physical model study of surrounding rock failure near a fault under the influence of footwall coal mining

2020 ◽  
Author(s):  
Shukun Zhang ◽  
Lu Lu ◽  
Ziming Wang ◽  
Shuda Wang
Keyword(s):  
Rock Mass ◽  
Physical Model ◽  
Hanging Wall ◽  
Coal Pillar ◽  
Vertical Displacement ◽  
Surrounding Rock ◽  
Pillar Width ◽  
Model Study ◽  
Working Face ◽  
Coal Pillars

AbstractA study of the deformation of the surrounding rock and coal pillars near a fault under the influence of mining is conducted on a physical model for the design of coal pillars to support and maintain the roofs of adjacent fault roadways. This research is based on the 15101 mining face in the Baiyangling Coal Mine, Shanxi, China, and uses simulation tests similar to digital speckle test technology to analyse the displacement, strain and vertical stress fields of surrounding rocks near faults to determine the influence of the coal pillar width. The results are as follows. The surrounding rock of the roadway roof fails to form a balance hinge for the massive rock mass. The vertical displacement, vertical strain and other deformation of the surrounding rock near the fault increase steeply as the coal pillar width decreases. The steep increase in deformation corresponds to a coal pillar width of 10 m. When the coal pillar width is 7.5 m, the pressure on the surrounding rock near the footwall of the fault suddenly increases, while the pressure on the hanging wall near the fault increases by only 0.35 MPa. The stress of the rock mass of the hanging wall is not completely shielded by the fault, and part of the load disturbance is still transmitted to the hanging wall via friction. The width of the fault coal pillars at the 15101 working face is determined to be 7.5 m, and the monitoring data verify the rationality of the fault coal pillars.

scholarly journals Study on Stress Relief of Hard Roof Based on Presplitting and Deep Hole Blasting

2020 ◽  
Vol 2020 ◽  
pp. 1-12
Author(s):  
Peng Gong ◽  
Yongheng Chen ◽  
Zhanguo Ma ◽  
Shixing Cheng
Keyword(s):  
Stress Distribution ◽  
Coal Mine ◽  
Coal Pillar ◽  
Deep Hole ◽  
Hard Roof ◽  
Formation Conditions ◽  
Coal Pillars ◽  
Mining Coal ◽  
The Impact ◽  
Pillar Size

For the problem that the hard roof causes wider end-mining coal pillar, and the roadway is greatly affected by mining, this paper took Shanxi Luning Coal Mine as the engineering background; based on the stress distribution characteristics of the coal pillar, the calculation method of the limit end-mining coal pillar size was given; considering the formation conditions and transmission forms of the advanced abutment stress, a method combining presplitting and deep hole blasting was proposed to weaken the advanced abutment stress. The numerical simulation was used to analyze the stress distribution of coal pillars, which was verified by on-site industrial tests. The results showed that the presplitting can achieve the blocking of stress. The closer it is to the peak of the abutment stress, the better the blocking effect. Deep hole blasting can weaken the source of the advanced abutment stress and reduce the peak of abutment stress. With the combination of the two blasting methods, the end-mining coal pillar size of Luning Coal Mine can be reduced to 60 m. The method combining presplitting and deep hole blasting can effectively reduce the end-mining coal pillar size and reduce the impact of mining on the deformation of the dip roadway.

COMBINED SIGNAL PROCESSING METHOD FOR DIAGNOSIS AND MONITORING OF THE INDUCTION MOTORS OPTIMIZED FOR EMBEDDED SYSTEMS

2021 ◽  
pp. 18-27
Author(s):  
A. L. Morozov
Keyword(s):  
Signal Processing ◽  
Embedded Systems ◽  
Induction Motors ◽  
Vibration Signal ◽  
Constant Load ◽  
Load Level ◽  
Monitoring Systems ◽  
Vibration Signals ◽  
Advantages And Disadvantages ◽  
Fractional Moments

Induction Motors (IM) play a key role in modern industry, so the condition monitoring systems are becoming increasingly relevant. Commercial monitoring systems are usually based on the measurement of IM’s vibrations and the further processing of the measured vibration signals. For those purposes the embedded systems (such as microcontrollers and inexpensive processors) are used. Embedded systems have limited resources, so data processing algorithms should have low computational complexity and require little memory. In this paper, the wellknown methods of processing vibration signals for fault diagnosis of the IM are considered and their main advantages and disadvantages for the implementation in embedded systems are highlighted. The previously proposed method based on a combination of the fast Fourier transform and the statistics of the fractional moments is optimized for vibration signal processing and implementation in embedded systems. The efficiency of diagnosis of such faults as eccentricity and a broke rotor bar, using the proposed method, is verified on the radial vertical vibrations measurements of the real motors under different constant load levels: no load, 50 % of the rated load, 75% of the rated load. The results show that this approach allows accurately diagnose the considered faults independently from the load level.

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