Simulation test of spalling failure of surrounding rock in rectangular tunnels with different height-to-width ratios

2020 ◽  
Vol 79 (6) ◽  
pp. 3207-3219 ◽  
Author(s):  
Feng-qiang Gong ◽  
Wu-xing Wu ◽  
Tian-bin Li
Keyword(s):  
Surrounding Rock ◽  
Simulation Test ◽  
Spalling Failure

scholarly journals Study on the Geo-Stress Loading and Excavation Unloading Devices of the Large-Scale Photoelastic Model Test for Deep-Buried Tunnels

2021 ◽  
Vol 2021 ◽  
pp. 1-17
Author(s):  
Jiaqi Guo ◽  
Binzhong Zhu ◽  
Xiliang Liu ◽  
Jing Luo ◽  
Zhaoyuan Li
Keyword(s):  
Model Test ◽  
Surrounding Rock ◽  
Test Method ◽  
Original Design ◽  
Simulation Test ◽  
Supporting Structure ◽  
Photoelastic Model ◽  
Loading System ◽  
The Stability ◽  
Current Loading

At present, theoretical analysis, numerical simulation, and other methods cannot be used to properly solve the problems associated with the stability and bearing capacity of the surrounding rock and its supporting system, the interaction between the supporting structure and surrounding rock, and the sharing role of each supporting structure, all of which commonly occur in deep tunnels. The model test method represented by the photoelastic test is still an important approach to study this kind of problem. In view of the deficiency of the current loading system of the photoelastic model test, we developed a geo-stress loading system for the photoelastic model test, which can simulate the in situ geo-stress environment of unidirectional loading, bidirectional equal pressure, bidirectional unequal pressure, and tridirectional unequal pressure. The universal retaining force loading rod can realize the stability and effective compensation of loading, which is an original design. According to the principle of umbrella-shaped expansion and contraction mechanism, an excavation unloading device for the photoelastic model test is developed, which can realize the simulation of various degrees of displacement release in the excavation process of deep tunnels and other underground projects. The loading simulation test and excavation unloading simulation test show that the geo-stress loading system and excavation unloading device developed in this paper are flexible, exhibit good performance, and can fully achieve their respective test functions. The combination of two devices can compensate for the insufficiency of the current photoelastic model test and will promote the application of photoelastic model tests in underground engineering applications such as deep tunnel projects.

scholarly journals Comprehensive Experimental Study of Affecting Factors on Rectangular Roadway Stability

2020 ◽  
Vol 2020 ◽  
pp. 1-10 ◽  
Author(s):  
Zhongcheng Qin ◽  
Bin Cao ◽  
Tan Li ◽  
Xin Yu ◽  
Guangbo Chen
Keyword(s):  
Numerical Simulation ◽  
Pressure Coefficient ◽  
Surrounding Rock ◽  
Affecting Factors ◽  
Similar Material ◽  
Simulation Test ◽  
Five Factors ◽  
Roadway Stability ◽  
The Stability ◽  
Similar Material Simulation

In this paper, two methods of orthogonal numerical simulation test and similar material simulation test are used to study the influence of five factors on the stability of rectangular roadway: roadway width, roadway height, roadway buried depth, lateral pressure coefficient of surrounding rock, and comprehensive strength of surrounding rock. The results show that five factors have influence on the stability of roadway, but the degree of influence is different. The depth of the tunnel and the coefficient of the side pressure of the surrounding rock are positively correlated with the stability of the tunnel; the comprehensive strength of the surrounding rock is negatively correlated with the stability of the tunnel, but the correlation between the width and height of the tunnel and the stability of the tunnel is not obvious. The results of orthogonal numerical simulation test and similar material simulation test verify each other. The results of the field practice of the Fucun coal mine are basically consistent with the results of the two test methods, which shows that the research results have a certain guiding effect on the field roadway support.

scholarly journals Complex Function Solution for Deformation and Failure Mechanism of Inclined Coal Seam Roadway

2021 ◽  
Author(s):  
Xianyu Xiong ◽  
Jun Dai ◽  
Xinnian chen ◽  
Yibo Ouyang
Keyword(s):  
Numerical Simulation ◽  
Coal Seam ◽  
Failure Mechanism ◽  
Physical Simulation ◽  
Complex Function ◽  
Surrounding Rock ◽  
Simulation Test ◽  
Deformation And Failure ◽  
Stress And Deformation ◽  
The Right

Abstract The stressed environment of the inclined coal seam roadway is complex and changeable, and the damage degree of surrounding rock increases, threatening the safe mining of coal mines. To improve the effectiveness of stability control of surrounding rock of this kind of roadway, the deformation and failure law of the inclined coal seam roadway is analyzed based on the complex function theory. It optimizes the solution process and accuracy of the mapping function coefficient and deduces the analytical solution of surrounding rock stress and deformation inclined coal seam roadway. The deformation and failure mechanism of surrounding rock in inclined coal seam roadway is revealed theoretically and verified by numerical simulation and physical simulation test. The results show that the stress and deformation of roadway surrounding rock in inclined coal seam show obvious asymmetric distribution characteristics. The stress and deformation of roadway surrounding rock on the right side are greater than on the left side. The two sides of the roadway, the right side of the roof and the roof angle of the right side, are the key positions of roadway stress concentration and deformation. According to the variation law of stress and deformation distribution of roadway surrounding rock, roadway cyclic deformation and failure theory is put forward. The numerical simulation and physical simulation test show that the deformation and failure law of roadway is consistent with the theoretical analysis results, and the cyclic deformation and failure mechanism of roadway in inclined coal seam is verified.

scholarly journals Physical Simulation Test on Surrounding Rock Deformation of Roof Rockburst in Continuous Tunneling Roadway

Minerals ◽  
2021 ◽  
Vol 11 (12) ◽  
pp. 1335
Author(s):  
Yaobin Shi ◽  
Yicheng Ye ◽  
Nanyan Hu ◽  
Yu Jiao ◽  
Xianhua Wang
Keyword(s):  
Physical Simulation ◽  
Imaging System ◽  
Fracture Network ◽  
Surrounding Rock ◽  
Failure Strength ◽  
Simulation Test ◽  
Deformation And Failure ◽  
Flexural Failure ◽  
Failure Evolution ◽  
Deep Rock

To study the occurrence process, as well as the temporal and spatial evolution laws, of rockburst disasters, the roof deformation of continuous heading roadways during rockburst was studied through a physical similarity simulation test with a high similarity ratio and low strength. The deformation and failure evolution law of the roadway roof in the process of rockburst were analyzed by using detection systems, including a strain acquisition system and a high-power digital micro-imaging system. The results show that the rockburst of the roadway roof can be divided into four stages: equilibrium, debris ejection, stable failure, and complete failure stage. According to the stress state of a I–II composite crack, the theoretical buckling failure strength of the surrounding rock is determined as 1.43 times the tensile strength. The flexural failure strength of a vanadium-bearing shale is 1.29–1.76 times its compressive strength. With continuous advancement in the mining time, the internal expansion energy of the roadway roof-surrounding rock in the equilibrium stage continuously accumulates. The fracture network continuously increases, developing to the stable failure stage, with bending deformation, accompanied by continuous particle ejection until the cumulative stress in the failure stage increases, and the tensile state of the rock surrounding the roof expands radially into deep rock. A microscopic damage study in similar material demonstrated that the deformation of the roadway roof is non-uniform and uncoordinated. In the four stages, the storage deformation of the rock surrounding the roadway roof changes from small accumulation to continuous deformation, to the left (or deep rock). Finally, the roadway roof-surrounding rock becomes completely tensioned. The research results presented in this study provide a reference for the prediction and control of rockburst in practical engineering.

Influence exerted by underground excavation shape and by effective stresses on the formation of a tensile strain zone at a depth greater than 1 km

2020 ◽  
pp. 67-75
Author(s):  
Van Min Nguyen ◽  
V. A. Eremenko ◽  
M. A. Sukhorukova ◽  
S. S. Shermatova
Keyword(s):  
Rock Mass ◽  
Cross Sections ◽  
Tensile Strain ◽  
Rock Fracture ◽  
Strain Analysis ◽  
Surrounding Rock ◽  
Underground Excavation ◽  
Secondary Stress ◽  
Principal Stresses ◽  
Mining Depth

The article presents the studies into the secondary stress field formed in surrounding rock mass around underground excavations of different cross-sections and the variants of principal stresses at a mining depth greater than 1 km. The stress-strain analysis of surrounding rock mass around development headings was performed in Map3D environment. The obtained results of the quantitative analysis are currently used in adjustment of the model over the whole period of heading and support of operating mine openings. The estimates of the assumed parameters of excavations, as well as the calculations of micro-strains in surrounding rock mass by three scenarios are given. During heading in the test area in granite, dense fracturing and formation of tensile strain zone proceeds from the boundary of e ≥ 350me and is used to determine rough distances from the roof ( H roof) and sidewalls ( H side) of an underground excavation to the 3 boundary e = 350me (probable rock fracture zone). The modeling has determined the structure of secondary stress and strain fields in the conditions of heading operations at great depths.

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.

scholarly journals Evolution regularity of temperature field of active heat insulation roadway considering thermal insulation spraying and grouting: A case study of Zhujidong Coal Mine, China

2021 ◽  
Vol 40 (1) ◽  
pp. 151-170
Author(s):  
Weijing Yao ◽  
Happiness Lyimo ◽  
Jianyong Pang
Keyword(s):  
Sensitivity Analysis ◽  
Temperature Field ◽  
Thermal Insulation ◽  
Wall Temperature ◽  
Heat Insulation ◽  
Surrounding Rock ◽  
Rock Temperature ◽  
Grouting Materials ◽  
Zone Radius ◽  
Thermal Conductivities

Abstract To study the active heat insulation roadways of high-temperature mines considering thermal insulation and injection, a high-temperature −965 m return air roadway of Zhujidong Coal Mine (Anhui Province, China) is selected as a prototype. The ANSYS numerical simulation method is used for the sensitivity analysis of heat insulation grouting layers with different thermal conductivities and zone ranges and heat insulation spray layers with different thermal conductivities and thicknesses; thus, their effects on the heat-adjusting zone radius, surrounding rock temperature field, and wall temperature are studied. The results show that the tunneling head temperature of the Zhujidong Mine is >27°C all year round, consequently causing serious heat damage. The heat insulation circle formed by thermal insulation spraying and grouting can effectively alleviate the disturbance of roadway airflow to the surrounding rock temperature field, thereby significantly reducing the heat-adjusting zone radius and wall temperature. The decrease in the thermal conductivities of the grouting and spray layers, expansion of the grouting layer zone, and increase in the spray layer thickness help effectively reduce the heat-adjusting zone radius and wall temperature. This trend decreases significantly with the ventilation time. A sensitivity analysis shows that the use of spraying and grouting materials of low thermal conductivity for thermal insulation is a primary factor in determining the temperature field distribution, while the range of the grouting layer zone and the spray layer thickness are secondary factors. The influence of the increased surrounding rock radial depth and ventilation time is negligible. Thus, the application of thermal insulation spraying and grouting is essential for the thermal environment control of mine roadways. Furthermore, the research and development of new spraying and grouting materials with good thermal insulation capabilities should be considered.

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