scholarly journals Field and Numerical Study on Deformation and Failure Characteristics of Deep High-Stress Main Roadway in Dongpang Coal Mine

2021 ◽  
Vol 13 (15) ◽  
pp. 8507
Author(s):  
Shuaigang Liu ◽  
Jianbiao Bai ◽  
Xiangyu Wang ◽  
Shuai Yan ◽  
Jiaxin Zhao
Keyword(s):  
Field Test ◽  
Negative Impact ◽  
Numerical Study ◽  
Coal Mines ◽  
High Stress ◽  
Damage Parameter ◽  
Surrounding Rock ◽  
Repair Work ◽  
Deformation And Failure ◽  
Crack Distribution

Deep horizontal high stress and high permeability geological factors appear when coal mines are converted to deep horizontal mining. When the roadway is damaged by the mining face, and the supporting components are mismatched, the deep roadways necessitate extensive repair work, which has a negative impact on the coal mining economy and sustainability. This paper carried out a series of field tests on the roadways deformation, crack distribution, and loose rock zone of the deep roadways. Furthermore, a numerical calculation model was established using the discrete element method (DEM) and calibrated with laboratory tests and RQD methods. Both the stress and crack distribution in the surrounding rock of the deep roadway were simulated. The field test and the corrected numerical model showed consistency. A FISH function was used to document the propagation of shear and tensile cracks around the roadway in three periods, and a damage parameter was adopted to evaluate the failure mechanism of the deep roadways under the dynamic stress disturbance. The matching of specifications of anchor cables, rock bolts, and anchoring agent is the primary point in the control of deep roadways, and revealing the stress evolution, crack propagation, and damage distribution caused by mining effects is another key point in deep roadway controlling. The field test and DEM in this paper provide a reference for the design of surrounding rock control of deep roadways and the sustainable development of coal mines.

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

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.

Analysis on Dynamic Transfer Characteristics of Low Geosynthetic-Reinforced Embankments Supported by CFG Piles Subjected to High-Speed Railway

2011 ◽  
Vol 368-373 ◽  
pp. 2575-2580 ◽  
Author(s):  
Long Long Fu ◽  
Quan Mei Gong ◽  
Yang Wang
Keyword(s):  
Field Test ◽  
High Speed ◽  
Dynamic Stress ◽  
Numerical Study ◽  
High Stress ◽  
High Speed Train ◽  
High Speed Railway ◽  
Railway Line ◽  
Transfer Characteristics ◽  
Reinforced Embankments

To investigate the dynamic transfer characteristics of low geosynthetic-reinforced embankments supported by CFG piles under high-speed train load, a numerical study has been conducted through dynamic finite element method on basis of the dynamic field test on a cross-section of Beijing-Shanghai high-speed railway. The comparative analysis on results of numerical study and field test indicated the distribution characteristics of vertical dynamic stress induced by high-speed train load in subgrade soil under railway line. The numerical results also suggested a high stress area in subgrade where vertical dynamic stress is over 1kPa. Conclusions of this work can provide reference for both design and estimation of long-term settlement of low geosynthetic-reinforced embankments supported by CFG piles for high-speed railway.

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

Geofluids ◽  
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.

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

Geofluids ◽  
2020 ◽  
Vol 2020 ◽  
pp. 1-15 ◽  
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.

scholarly journals Research on Hydraulic Fracturing Pressure Relief Technology in the Deep High-Stress Roadway for Surrounding Rock Control

2021 ◽  
Vol 2021 ◽  
pp. 1-13
Author(s):  
Wen Zhai ◽  
Yachao Guo ◽  
Xiaochuan Ma ◽  
Nailv Li ◽  
Peng Zhang ◽  
...  
Keyword(s):  
Numerical Simulation ◽  
Hydraulic Fracturing ◽  
High Stress ◽  
Economic Benefits ◽  
Surrounding Rock ◽  
Pressure Relief ◽  
Deformation And Failure ◽  
Working Face ◽  
Roadway Stability ◽  
Surrounding Rock Control

With the increase of mining depth in underground engineering, deep ground pressure has an extremely unfavorable impact on safety production and the economic benefits of coal mines and the control of the roadway stability in deep mines are gradually highlighted. In this study, the working face 14203 of the Zaoquan coal mine was taken as the engineering background, the deformation mechanism of surrounding rock in the deep-buried high-stress roadway was analyzed, and the hydraulic fracturing pressure relief technology in the advanced roadway was proposed for surrounding rock control. Finally, the numerical simulation and field tests were used to validate the comprehensive effect of the proposed technology. Without damaging the roadway stability in the working face, the hydraulic fracturing pressure relief technology can optimize the stress environment and stability of the roadway through the artificial control of the roof fracture position. The numerical simulation shows that under the action of hydraulic fracturing, the cutting slot is formed, the deformation and failure mode of the roof are changed, the stress of surrounding rock is reduced, and the development of the plastic zone of surrounding rock is limited. As a result, the stability of surrounding rock in the roadway is effectively protected. The field test shows that after the adoption of hydraulic fracturing pressure relief technology, the roof subsidence, floor separation, bolt stress, and cable stress decrease, and the deformation of surrounding rock is reduced significantly. Therefore, hydraulic fracturing pressure relief technology is verified as an effective method to control the large deformation of the surrounding rock in the deep-buried roadway.

scholarly journals Deformation Failure and Support Test of Surrounding Rock in Deep Arched Roadway with Straight Wall

2021 ◽  
Vol 2021 ◽  
pp. 1-11
Author(s):  
Shuqi Pan ◽  
Shuaitao Liu ◽  
Liming Cao ◽  
Jianqiang Guo ◽  
Chao Yuan
Keyword(s):  
Large Scale ◽  
High Stress ◽  
Vertical Direction ◽  
Test System ◽  
Surrounding Rock ◽  
Initial Stress State ◽  
Deformation And Failure ◽  
Anchor Cable ◽  
Full Face ◽  
Roadway Deformation

The deformation and failure of the uphill roadway on the 3rd horizontal track in the No. 6 Mine of Pingdingshan Coal Group was taken as the engineering background. The similar simulation material of the roadway surrounding rock with quartz sand as the aggregate, cement as the cementing agent, and gypsum powder as the regulator was selected. Through mechanical tests on 25 sets of specimens with different proportions, the best proportion of similar simulated materials for simulating the deformation and failure of the surrounding rock of the roadway was obtained. Later, a large-scale deep mine roadway simulation test system independently developed by the company was used to carry out the roadway deformation and failure test. First, load the test body to the set initial stress state, and then carry out the full-face excavation and unloading of the roadway; finally, load it in the vertical direction until the roadway wall is damaged. It can realize the actual effect of simulation of roadway deformation and failure under the path of “high stress + internal unloading + stress adjustment.” The results showed that after the deep roadway is excavated with preload and high stress, the surrounding rock deformation, failure, and instability of the roadway mainly experience 3 periods: the first period is the period of uniform deformation of the roadway surrounding rock, the second period is the development period of the roadway surrounding rock slab structure, and the third period is the period of instability of the roadway surrounding rock slab structure. Combined with the time period of deformation and failure of the surrounding rock of the roadway, the damage scope of the surrounding rock and the actual situation of the site engineering. A step-by-step combined roadway repair and support plan of “bolt mesh + shotcrete + full-face hollow grouting anchor cable” with hollow grouting anchor cable as the core was determined. The stability of the repaired roadway has been significantly improved, ensuring the long-term use of the roadway.

scholarly journals Deformation Mechanism and Surrounding Rock Control in High-Stress Soft Rock Roadway: A Case Study

2021 ◽  
Vol 2021 ◽  
pp. 1-15
Author(s):  
Yuwen Gao ◽  
Chen Wang ◽  
Yong Liu ◽  
Yuyang Wang ◽  
Lianchang Han
Keyword(s):  
Theoretical Analysis ◽  
High Stress ◽  
Soft Rock ◽  
Stability Control ◽  
Steel Tube ◽  
Field Application ◽  
Industrial Test ◽  
Surrounding Rock ◽  
Guizhou Province ◽  
Deformation And Failure

Stability control for soft and broken surrounding rock of roadways is one important segment of mining support. Taking 1412 Roadway of a mine in Guizhou province as a research background, this paper studies the large deformation of surrounding rock and the failure of bolts and cables. The deformation and failure mechanism are analyzed by related theoretical analysis and field survey. Then, the feasibility of the composite controlling scheme, bolts and cables + grouting + steel tube concrete support, is verified by theoretical analysis, numerical simulation, and industrial test. Following results can be obtained: main reasons leading to the deformation of surrounding rock and the failure of cables and blots in the roadway are low strength and poor self-stability of surrounding rock, complex stress environment, low support resistance, and lack of reinforced support in crucial supporting sites; the control scheme can reduce the surrounding rock deformation by 40%, which meets the requirements of field application so that this practice can provide some guidance for other similar projects.

Research on Guided Roadway Pressure Relief Combined Supporting Technology in High Stress Roadway

2014 ◽  
Vol 986-987 ◽  
pp. 2180-2183 ◽  
Author(s):  
Wan Jiang Li
Keyword(s):  
Coal Mining ◽  
Coal Mine ◽  
High Stress ◽  
Surrounding Rock ◽  
Pressure Relief ◽  
Deformation And Failure ◽  
Major Subject ◽  
Roadway Deformation ◽  
Important Significance

The problem of maintaining the surrounding rock in deep high-stress roadway has been a major subject in coal mining. The analysis of high stress roadway supporting mechanism, and the research on high stress roadway supporting technology as well as its adaptability have important significance in improving the support technology of mine. This paper analyzes the features and reasons of the high stress roadway deformation and failure, and the high stress roadway supporting measure is put forward. At the same time the paper systematically analyzed the guided roadway pressure relief combined support technology which has been used in the transporting roadway in Taoyang Coal Mine and achieved good.

scholarly journals 764 Human Factors in Operative Theatres During the Covid-19 Pandemic: A Cross-sectional Analysis of Operating Theatre Staff Experiences in a Regional Centre

2021 ◽  
Vol 108 (Supplement_2) ◽  
Author(s):  
L E Murchison ◽  
R Anbarasan ◽  
A Mathur ◽  
M Kulkarni
Keyword(s):  
Human Factors ◽  
Online Survey ◽  
Situational Awareness ◽  
Negative Impact ◽  
High Stress ◽  
Operating Theatre ◽  
Free Text ◽  
Cross Sectional ◽  
Chi Squared ◽  
Theatre Staff

Abstract Introduction In the already high-risk, high-stress environment of the operating theatre, operating during Covid-19 has brought its own unique challenges. Communication, teamwork and anxiety related new operating practices secondary to Covid-19 are hypothesised to have a negative impact on patient care. Method We conducted a single-centre online survey of operating theatre staff from 22nd June–6th July 2020. Respondents completed 18 human factors questions related to COVID-19 precautions including communication, teamwork, situational awareness, decision making, stress, fatigue, work environment and organisational culture. Questions consisted of yes/no responses, multiple choice and Likert items. Kruskall-Wallis tests, Chi-Squared, Mann Whitney U tests, Spearman’s correlation coefficient, lambda and Cramer’s V tests were used. Free-text responses were also reviewed. Results 116 theatre staff responded. Visual (90.5%), hearing/ understanding (96.6%) difficulties, feeling faint/lightheaded (66.4%) and stress (47.8%) were reported. Decreased situational awareness was reported by 71.5% and correlated with visors (r = 0.27 and p = 0.03) and FFP2/3 mask usage (r = 0.29 and p = 0.01). Reduced efficiency of theatre teams was reported by 75% of respondents and 21.5% felt patient safety was at greater risk due to Covid-19 precautions in theatre. Conclusions Organisational adjustments are required, and research focused on development of fit-for-purpose personal protective equipment (PPE).

Sign in / Sign up

Export Citation Format

Share Document