scholarly journals Study on the deformation and failure mechanisms of a coal wall in a deeply buried longwall working face with a weak roof

2021 ◽  
Vol 861 (5) ◽  
pp. 052054
Author(s):  
Maolin Tian ◽  
Lijun Han ◽  
Qingbin Meng ◽  
Xuxu Yang ◽  
Qiang Feng ◽  
...  
Keyword(s):  
Failure Mechanisms ◽  
Deformation And Failure ◽  
Working Face ◽  
Coal Wall

scholarly journals Comprehensive Measurement of the Deformation and Failure of Floor Rocks: A Case Study of the Xinglongzhuang Coal Mine

Geofluids ◽  
2020 ◽  
Vol 2020 ◽  
pp. 1-14
Author(s):  
Hao Liu ◽  
Pu Wang ◽  
Weihe Zhang ◽  
Qiang Liu ◽  
Lijun Su
Keyword(s):  
Coal Mine ◽  
Abutment Pressure ◽  
Three Dimensional ◽  
Strain Sensing ◽  
Floor Rock ◽  
Deformation And Failure ◽  
Working Face ◽  
Floor Failure ◽  
Coal Wall ◽  
Different Depths

The isolated island panel 10304 of the Xinglongzhuang coal mine was used as the research subject to study the deformation and damage characteristics of the coal seam floor. The damage of the floor was studied using the borehole strain sensing method and borehole imaging technology, and FLAC3D was used to study the influence of abutment pressure on floor failure. The result shows that the floor under the superimposed area which is affected by lateral and advanced abutment pressure is damaged firstly, and the maximum depth reaches 26 m, other areas of the working face about 23 m. The degree of deformation and failure of floor rock at different depths is decreased. The deformation damage increases with the advancement of the working face until a certain distance at the same depth. The hole image can clearly show the influence range of the abutment pressure in front of the coal wall and influence the degree of the advancement and lag by means of the strain increment curve for each sensor probe and the images from different drilled positions. On the basis that the results of simulation and field measurement are consistent, the results can reflect the three-dimensional failure characteristics of the whole island working face floor in the process of coal mining more comprehensively and accurately; moreover, they also can provide important information for mine flood prevention and ecological environment protection.

Deformation and Failure Mechanisms of Austenitic Piping Under the Influence of Oxyhydrogen Reactions

2016 ◽  
Author(s):  
Stefan Offermanns ◽  
Stefan Weihe
Keyword(s):  
Failure Mechanisms ◽  
Shear Bands ◽  
Adiabatic Shear ◽  
Material Behavior ◽  
Inert Gas ◽  
Materials Testing ◽  
Failure Model ◽  
Adiabatic Shear Bands ◽  
Deformation And Failure ◽  
Gas Component

The present paper deals with the deformation and failure mechanisms of austenitic piping under the influence of oxyhydrogen reactions for the safety evaluation of incident scenarios in technical installations based on previous work of the author [1–5]. For the characterization of the processes, detonation tests performed at the Materials Testing Institute University of Stuttgart (MPA Stuttgart) have been used. The aim of these experiments was to study the detonation processes in head spray cooling piping of boiling water reactors. The experiments were performed on austenitic pipes with an outer diameter of O. D. = 114.3 mm and various wall thicknesses. Oxyhydrogen was used in its stoichiometric ratio of 2H2+O2 mixed with various amounts of an inert gas component. These tests have shown that less amounts of reactive gas may result in a stronger reaction of the pipe structure. This observation is attributed to the influence of the so-called overdriven detonation. Depending on the ratio of oxyhydrogen to the inert gas component and the pipe-wall thickness, adiabatic shear bands can occur in the piping structure. Adiabatic shear bands are very narrow zones with intense localized shear deformations due to the conversion of a significant portion of strain energy into heat. In order to describe this phenomenon numerically, a strain-based failure model was used which can reflect material damage over a wide range of different stress states. However, it has shown that damage of the studied material depends significantly on the Lode angle. Furthermore, no clear dependence of the failure limit on the loading rate has been found for the studied material. For the constitutive description of the material behavior under the occurring loading rates and temperatures suitable material models were selected and the required parameters have been evaluated experimentally and verified by numerical methods. With the aid of this constitutive description of the material behavior and the failure model numerical simulations of the detonation tests were carried out.

scholarly journals Research on Deformation Mechanisms of a High Geostress Soft Rock Roadway and Double-Shell Grouting Technology

Geofluids ◽  
2021 ◽  
Vol 2021 ◽  
pp. 1-13
Author(s):  
Fengnian Wang ◽  
Shizhuang Chen ◽  
Pan Gao ◽  
Zhibiao Guo ◽  
Zhigang Tao
Keyword(s):  
Mechanical Properties ◽  
Rock Mass ◽  
Large Deformation ◽  
Coal Mine ◽  
Soft Rock ◽  
In Situ Stress ◽  
Deformation Monitoring ◽  
Deformation And Failure ◽  
Working Face ◽  
High Geostress

In this study, the deformation characteristics and mechanical properties of coal and rock mass in the S2N5 working face of the Xiaokang coal mine are analyzed to address the problem of large deformation of soft rocks with high in situ stress surrounding roadways. Through a newly developed grouting pipe, a double-shell grouting technology, consisting of low-pressure grouting and high-pressure split grouting, is proposed for the Xiaokang coal mine. In addition, the effect of grouting is evaluated by borehole peeping and deformation monitoring. The results show that the double-shell grouting technology can effectively improve the overall mechanical properties of the surrounding coal and rock mass, preventing the large deformation and failure of the roadway. This technology can be useful when analyzing and preventing large deformation of soft rock roadways.

scholarly journals Research on Control of Rib Spalling Disaster in the Three-Soft Coal Seam

2021 ◽  
Vol 2021 ◽  
pp. 1-15
Author(s):  
Feng Cui ◽  
Tinghui Zhang ◽  
Xiaoqiang Cheng
Keyword(s):  
Coal Seam ◽  
Field Experiments ◽  
Simulation Experiment ◽  
Current Status ◽  
Soft Coal ◽  
Grouting Pressure ◽  
Working Face ◽  
Coal Wall ◽  
Soft Coal Seam ◽  
Seam Mining

Rib spalling disaster at the coal mining faces severely restricted the safe and efficient output of coal resources. In order to solve this problem, based on the analysis of the current status of rib spalling in the three-soft coal seam 1508 Working Face of Heyang Coal Mine, a mechanical model of sliding-type rib spalling was established and the main influencing factors that affect rib spalling are given. The mechanism of grouting technology to prevent and control rib spalling has been theoretically analyzed. A similarity simulation experiment is used to analyze the change law of roof stress under the condition of three-soft coal seam mining. The optimal grouting pressure is determined by a numerical simulation experiment. And, silicate-modified polymer grouting reinforcement materials (SMPGMs) are used in field experiments. After twice grouting operations in the 1508 Working Face, the coal wall was changed from the original soft and extremely easy rib spalling to a straight coal wall and the amount of rib spalling has been reduced by 57.45% and 48.43, respectively. And, the mining height has increased by 0.16 m and 0.23 m, respectively. The experimental results show that the rib spalling disaster of the three-soft coal seam has been effectively controlled.

Deformation and Failure Mechanisms of Thermoelectric Type-I Clathrate Ba8Au6Ge40

2022 ◽  
Author(s):  
Xiaolian Zhang ◽  
Pengcheng Zhai ◽  
Xiege Huang ◽  
Sergey I. Morozov ◽  
Bo Duan ◽  
...  
Keyword(s):  
Failure Mechanisms ◽  
Type I ◽  
Deformation And Failure

Deformation and failure mechanisms of granular soil around pressurised shallow cavities

Géotechnique ◽  
2021 ◽  
pp. 1-45
Author(s):  
Fernando Patino-Ramirez ◽  
Floriana Anselmucci ◽  
Edward Andò ◽  
Gioacchino Viggiani ◽  
Bernardo Caicedo ◽  
...  
Keyword(s):  
Failure Mechanisms ◽  
Granular Soil ◽  
Deformation And Failure ◽  
Shallow Cavities

scholarly journals Application Study on Active Advanced Support Technology in Deep Roadway under Mine Goaf

Geofluids ◽  
2020 ◽  
Vol 2020 ◽  
pp. 1-13
Author(s):  
Pengfei Jiang ◽  
Peng Xiao ◽  
Fanbao Meng ◽  
Suolin Jing ◽  
Jingkai Zhang ◽  
...  
Keyword(s):  
Base Point ◽  
Surrounding Rock ◽  
Maximum Displacement ◽  
Measuring Point ◽  
Deformation And Failure ◽  
Anchor Cable ◽  
Working Face ◽  
Allowable Range ◽  
Advanced Support ◽  
Working Procedure

To solve the problems of the rapid advance of the working face was delayed by complicated working procedure and high labor intensity, and the severe damage of roof bolt (anchor cable) induced by advanced hydraulic support, the deformation characteristics of surrounding rock, and the supporting principle of grouting truss anchor cable were analyzed theoretically by taking the roadway of 3_(down) coal seams 2326# working face in Sanhekou coal mine as the research object; then, the mechanical model of supporting structure of roadway under goaf was established. Based on this model, the optimal supporting scheme was determined, and the active advanced support technology scheme of “advanced grouting truss anchor cable” was proposed to take the place of the existing single pillar. The deformation and failure characteristics of surrounding rock of the working face leading roadway were observed and analyzed on-site. Within the allowable range of reading error, the results showed that the maximum displacement of medium-deep base point and shallow base point of two roadways was 15.2 cm and 10.9 cm, respectively; the pressure value had a more obvious jump increase when the distance between each measuring point and the working face was about 35 m, which means the range is strongly affected by the advance mining, and the area affected by advanced mining was 35 m ahead of the working face. It was observed that the lowest position of roof separation development ranged from 0.71 m to 2.73 m. The separation layer was generally distributed in the range of 0.73 m-2.49 m, and the fracture area was roughly distributed in the range of 0.01 m-0.62 m. Under the condition of overlying goaf, there was a complete stress structure, which can meet the requirements of suspension support.

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