scholarly journals Study on Influence of Joint Distribution on Surrounding Rock Failure of an Underground Tunnel

Geofluids ◽  
2021 ◽  
Vol 2021 ◽  
pp. 1-12
Author(s):  
Wanrong Liu ◽  
Chao Peng ◽  
Baoliang Zhang
Keyword(s):  
Bearing Capacity ◽  
Rapid Development ◽  
Geological Structure ◽  
Surrounding Rock ◽  
Joint Spacing ◽  
Failure Characteristics ◽  
Underground Tunnel ◽  
Artificial Disturbance ◽  
Propagation Law ◽  
The Relationship

Due to geological structure and artificial disturbance, a large number of joints and fissures are formed in the surrounding rock of an underground tunnel. In order to study the influence of joints on the failure characteristics of tunnels, three test schemes with different joint lengths, joint spacing, and joint positions are designed. The results show that the bearing capacity of the tunnel decreases with the increase in the joint length. With the increase in joint spacing, the bearing capacity of the tunnel decreases first and then increases. The crack propagation law of the three test schemes has experienced four stages: no crack, crack initiation, crack rapid development, and crack gradual reduction. The location of joints has the greatest influence on the failure mode of the tunnel. The crack is most likely to appear at the top of the tunnel and expand along the joint, mainly because it is easy to form tensile stress at the top of the tunnel and compressive stress concentration at the joint tip. Therefore, when excavating the tunnel in the underground space, the influence of joints on the tunnel should be considered. Analyzing the relationship between the tunnel and joints has important practical guiding significance for the control of the surrounding rock of the tunnel. Finally, the failure results of the indoor physical model and numerical model are compared and analyzed. They are in good agreement, which also reflects the rationality of numerical simulation.

scholarly journals Rockburst Precursors and the Dynamic Failure Mechanism of the Deep Tunnel: A Review

Energies ◽  
2021 ◽  
Vol 14 (22) ◽  
pp. 7548
Author(s):  
Yulong Chen ◽  
Junwen Zhang ◽  
Jiahao Zhang ◽  
Bin Xu ◽  
Luji Zhang ◽  
...  
Keyword(s):  
Failure Mechanism ◽  
Dynamic Instability ◽  
Rapid Development ◽  
Prediction Method ◽  
Surrounding Rock ◽  
Deep Tunnel ◽  
Dynamic Failure ◽  
Failure Characteristics ◽  
Underground Caverns ◽  
The Stability

With the rapid development of underground caverns in the fields of hydraulic engineering, mining, railway and highway, the frequency, and intensity of rockburst and dynamic instability have gradually increased, which has become a bottleneck restricting the safe construction of deep caverns. This paper presents a review of the current understanding of rockburst precursors and the dynamic failure mechanism of the deep tunnel. Emphasis is placed on the stability of the surrounding rock of the deep tunnel, the rockburst prediction method, and the dynamic failure characteristics of the surrounding rock of the deep tunnel. Throughout the presentation, the current overall gaps in understanding rockburst precursors and the dynamic failure mechanism of deep tunnels are identified in an attempt to stimulate further research in these promising directions by the research community.

Research on Flexural Behavior of Damaged RC Beams Strengthened with Basalt Fiber Reinforced Polymer

2013 ◽  
Vol 834-836 ◽  
pp. 762-767
Author(s):  
Hai Liang Wang ◽  
Xing Long Yuan
Keyword(s):  
Bearing Capacity ◽  
Strain Distribution ◽  
Basalt Fiber ◽  
Fiber Reinforced Polymer ◽  
Flexural Behavior ◽  
Rc Beams ◽  
Failure Characteristics ◽  
Reinforced Polymer ◽  
Loading Method ◽  
The Relationship

The experiment study on flexural behavior was carried out on six damaged RC beams strengthened by BFRP and two common beams by the way of three point loading method. The failure characteristics, flexural capacity, deflection, strain distribution and the influence of the different layers of BFRP was observed and analyzed. Results show that the bearing capacity of the damaged RC beams strengthened with BFRP is enhanced with the layers increasing, and the relationship is not linear; the bearing capacity of the specimen increased by 79.98% when five layers are pasted; with the increase of paste layers of BFRP, the peel failure mode is more likely to occur.

scholarly journals Research on Failure Characteristics and Zoning Control Technology of Thick-Soft Surrounding Rock for Deep Gob-Side Entry Retaining

2020 ◽  
Vol 2020 ◽  
pp. 1-14
Author(s):  
Jingke Wu ◽  
Wenbin Zhou ◽  
Hong Tao ◽  
Haowen Bai ◽  
Wei Yin ◽  
...  
Keyword(s):  
Bearing Capacity ◽  
Large Deformation ◽  
Failure Modes ◽  
Surrounding Rock ◽  
Control Technology ◽  
Failure Characteristics ◽  
Deformation And Failure ◽  
Rock Structure ◽  
Roof Fall ◽  
And Control

Controlling the large deformation caused by bed separation failure of thick and soft surrounding rock in gob-side entry retaining is difficult. The deformation and failure modes of thick and soft surrounding rock are summarized and classified based on field research, theoretical analysis, laboratory tests, and actual measurements. Systematic research is conducted on the lithologic characteristics, failure characteristics, and control methods of the surrounding rock. The research findings are as follows: (1) The low strength, softening, and water swelling of thick mudstone, as well as its cataclasis, dilatancy, and long-term creep under strong mining and high stress are the objective reasons for large deformation of the surrounding rock. (2) Due to the weak stability of the surrounding rock-support structure and low collaborative roof side bearing capacity, no complete supporting structure is formed with the supporting system, causing the support body in each area to be crushed one by one, which is the subjective reason for the deformation and failure of the surrounding rock. (3) The deformation and failure characteristics of thick and soft surrounding rock in gob-side entry retaining are primarily divided into eight types: roof bending and sinking type, roof cutting along filling body, rib spalling type, roof fall type, filling body rotation type, filling body crushing type, roof step type, and roof cutting along the coal side. The initial points and key points for a chain reaction of each failure type are determined. (4) The surrounding rock is divided into 10 support zones at four levels, and control technology for “zonal support and overall reinforcement” is put forward. The mechanical effect of the support body in each zone and its role in maintaining the stability of surrounding rock are analyzed. This technology can ensure the integrity of the surrounding rock structure and improve the roof side collaborative bearing capacity.

scholarly journals Method for designing the optimal sealing depth in methane drainage boreholes to realize efficient drainage

2021 ◽  
Author(s):  
Minghao Yi ◽  
Liang Wang ◽  
Congmeng Hao ◽  
Qingquan Liu ◽  
Zhenyang Wang
Keyword(s):  
Drainage System ◽  
Surrounding Rock ◽  
High Concentration ◽  
Failure Characteristics ◽  
Coal Mine Methane ◽  
Methane Drainage ◽  
Sealing Material ◽  
Sealing Performance ◽  
Key Factor ◽  
Quantitative Analysis Method

AbstractThe purpose of underground methane drainage technology is to prevent methane disasters and enable the efficient use of coal mine methane (CMM), and the sealing depth is a key factor that affects the performance of underground methane drainage. In this work, the layouts of in-seam and crossing boreholes are considered to analyze the stress distribution and failure characteristics of roadway surrounding rock through a numerical simulation and field stress investigation to determine a reasonable sealing depth. The results show that the depths of the plastic and elastic zones in two experimental coal mines are 16 and 20 m respectively. Borehole sealing minimizes the air leakage through the fractures around the roadway when the sealing material covers the failure and plastic zones, and the field test results for CMM drainage at different sealing depths indicate that the CMM drainage efficiency increases with increasing sealing depth but does not change once the sealing depth exceeds the plastic zone. Moreover, sealing in the high-permeability roadway surrounding rock does not have a strong influence on the borehole sealing performance. Considering these findings, a new CMM drainage system for key sealing in the low-permeability zone was developed that is effective for improving the CMM drainage efficiency and prolonging the high-concentration CMM drainage period. The proposed approach offers a valuable quantitative analysis method for selecting the optimum sealing parameters for underground methane drainage, thereby improving considerably the drainage and utilization rates of CMM.

Study on the Prediction Method of Tunnel Surrounding Rock Pressure Based on the Theory of Progressive Destruction

2012 ◽  
Vol 446-449 ◽  
pp. 1432-1436
Author(s):  
Suo Wang
Keyword(s):  
Rock Pressure ◽  
Characteristic Curve ◽  
Prediction Method ◽  
Surrounding Rock ◽  
Progressive Damage ◽  
Tunnel Excavation ◽  
Practical Engineering ◽  
Surrounding Rock Pressure ◽  
The Relationship ◽  
Rock Parameters

In order to predict tunnel surrounding rock pressure, this paper puts forward a series of dynamic numerical simulative model on the tunnel excavation. According to the change of rock damage in the construction program, it adjusts dynamically the mechanical material parameters of surrounding rock. So the model achieves the purpose which is controlling and simulating the process of tunnel progressive damage. In accordance with the numerical simulative results, it analyzes the relationship between the rock parameters with the plastic strain, radial displacement. Then this paper proposes a prediction method of tunnel surrounding rock pressure based on the theory of the progressive damage and method of characteristic curve. Finally, it compares the pressure on the numerical simulative models with on the site date, and it proves that the prediction method has practical engineering value.

Nondestructive Test on Typical Roadway Supports of a Mine via Drilling Core and Ground Penetrating Radar

2011 ◽  
Vol 368-373 ◽  
pp. 2411-2416
Author(s):  
Jian Ping Han ◽  
Hai Peng Liu
Keyword(s):  
Ground Penetrating Radar ◽  
Geological Structure ◽  
Surrounding Rock ◽  
Potential Threat ◽  
Real Performance ◽  
Design Requirements ◽  
And Performance ◽  
The Stability ◽  
Ground Penetrating ◽  
Drilling Core

Temporary or permanent supports are necessary in underground construction for maintaining the stability and limiting the damage of surrounding rock. Due to the uncertainty of geological structure, the specificity of the underground environment as well as other factors, the quality and performance of supporting structure are often difficult to satisfy the design requirements, which not only seriously affects the normal construction and operation of mines but also has the potential threat to the safety of underground production. In order to investigate the influence of the unfavorable geologic environment on supporting concrete and evaluate the real performance of roadway supports of a mine, 17 typical projects were chosen and the strength of supporting concrete was detected by nondestructive drilling core method. The result shows that the strength is widely less than the design value. Furthermore, 4 projects of them were investigated by the ground penetrating radar (GPR) in order to evaluate the feasibility of GPR in the performance investigation of the roadway supports of a mine. The results indicate that ground penetrating radar is capable of measuring the thickness of the support, the distribution of rebars and the defects of the surrounding rock.

Research on the Impact of Information Security Certification and Concealment onFinancial Performance

2022 ◽  
Vol 30 (3) ◽  
pp. 0-0
Keyword(s):  
Information Security ◽  
Financial Performance ◽  
Positive Impact ◽  
Rapid Development ◽  
International Standards ◽  
Corporate Decisions ◽  
Using Data ◽  
The Impact ◽  
The Relationship ◽  
Iso 27001

With the rapid development of information technology, information security has been gaining attention. The International Organization for Standardization (ISO) has issued international standards and technical reports related to information security, which are gradually being adopted by enterprises. This study analyzes the relationship between information security certification (ISO 27001) and corporate financial performance using data from Chinese publicly listed companies. The study focusses on the impact of corporate decisions such as whether to obtain certification, how long to hold certification, and whether to publicize information regarding certification. The results show that there is a positive correlation between ISO 27001 and financial performance. Moreover, the positive impact of ISO 27001 on financial performance gradually increases with time. In addition, choosing not to publicize ISO 27001 certification can negatively affect enterprise performance.

Strength Assessments of Concrete-Filled Steel Tubular Support of Soft Rock Roadway

2013 ◽  
Vol 838-841 ◽  
pp. 1884-1890 ◽  
Author(s):  
Guang Long Qu ◽  
Yan Fa Gao ◽  
Liu Yang ◽  
Bin Jing Xu ◽  
Guo Lei Liu ◽  
...  
Keyword(s):  
Bearing Capacity ◽  
Coal Mine ◽  
Soft Rock ◽  
Surrounding Rock ◽  
Flexural Performance ◽  
Laboratory Test Results ◽  
Different Types ◽  
Soft Rock Roadway ◽  
Core Concrete ◽  
Rock Roadway

Compared with I-shaped and U-shaped supports in soft rock roadway, concrete-filled steel tubular (CFST) support, as a new supporting form, has stronger bearing capacity with reasonable price. So it is becoming more and more popular in roadway supporting of coal mine in China. In this article, the surrounding rock in soft rock roadway was classified into three different types: hard rock in deep coal mine, soft surrounding rock, extremely soft surrounding rock. And, according to the characteristics of deformation failure of the CFST support and the surrounding rock in the industrial tests, three different strength assessments, including assessment of axial compressive strength, assessment of lateral flexural performance, assessment of hardening rate of core concrete, were proposed through mechanical analysis and laboratory tests for the three different types of the surrounding rock, respectively. Moreover, aimed to insufficient flexural strength of the support or low hardening rate of the core concrete in some of the roadway supporting, strengthening lateral flexural performance or making early strength concrete was necessary for the above unfavorable situations. The laboratory test results showed that the ultimate bearing capacity for the CFST support with φ194*8mm of steel tube reinforced by φ38mm round steel was 31% greater than that of the unreinforced one, 177% greater than that of the U-shaped one with equivalent weight per unit length.

Study on the Range of Freeze-Thaw of Surrounding Rock from a Cold-Region Tunnel and the Effects of Insulation Material

2011 ◽  
Vol 399-401 ◽  
pp. 2222-2225 ◽  
Author(s):  
Peng Qi ◽  
Jing Zhang ◽  
Zhi Rong Mei ◽  
Yue Xiu Wu
Keyword(s):  
Mass Transfer ◽  
Heat And Mass Transfer ◽  
Surrounding Rock ◽  
Insulation Material ◽  
The Finite Element Method ◽  
Cold Region ◽  
Coupled Problem ◽  
Fluid Transfer ◽  
Tunnel Depth ◽  
The Relationship

A mathematical models for the coupled problem is established by considering heat and mass transfer and phase change for rock mass at low temperature, according to the theory of heat and mass transfer for porous media. It is considered of the influences of fluid transfer on the heat conduction and the temperature gradient on the seepage. By adopting the finite element method, the numerical simulation is done to study the range of frost-thaw of surrounding rock and the effects of insulation material in cold regions, which analysis the influence of tunnel depth and surrounding rock class on the range of frost-thaw, the change law of the frost-thaw area of different insulation material and the relationship between the frost-thaw area and the thickness of insulation material.

scholarly journals Green innovation, government incentive and enterprise performance are explored from the perspective of game

2021 ◽  
Vol 275 ◽  
pp. 02006
Author(s):  
Xiaohui Ren
Keyword(s):  
Game Theory ◽  
Rapid Development ◽  
Enterprise Performance ◽  
Green Innovation ◽  
Green Development ◽  
Pollution Problem ◽  
Environmental Pollution Problem ◽  
And Performance ◽  
The Relationship

The rapid development of economy brings serious environmental pollution problem. Green innovation, as the connection point between government environmental regulation measures and sustainable green development of enterprises, has become one of the important choices for the transformation and development of enterprises. Based on the classic model of “prisoner’s dilemma” in game theory, this paper deeply analyzes the relationship between green innovation and performance. It is found that it is easy to get into trouble if only relying on the spontaneous green innovation within the enterprise. Applying appropriate pressure outside the enterprise can promote the change of green innovation and bring long-term benefits to the enterprise.

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