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.

scholarly journals Numerical Simulation Analysis of Unsteady Temperature in Thermal Insulation Supporting Roadway

2019 ◽  
Vol 2019 ◽  
pp. 1-8
Author(s):  
Shuguang Zhang ◽  
Pingping Lu ◽  
Hongwei Wang
Keyword(s):  
Heat Transfer ◽  
Numerical Simulation ◽  
Temperature Field ◽  
Heat Transfer Coefficient ◽  
Heat Exchange ◽  
Thermal Insulation ◽  
Heat Insulation ◽  
Surface Heat ◽  
Surrounding Rock ◽  
Surface Heat Transfer Coefficient

High geothermal hazard is a basic problem that must be solved in deep mining; thereby the research on thermal insulation supporting for high temperature control of deep roadway is increasing. However, the quantitative analysis of its thermal insulation effect is yet to be carried out. By building the physical model and control equations of the thermal insulation supporting roadway and considering heat-humidity transfer at wall, the temperature field distribution of surrounding rock and airflow is numerically calculated. Based on numerical simulation results, the evolution law of temperature with ventilation time is analyzed at airflow inlet, outlet, and different sections, then the variation law of surface heat transfer coefficient with position and time is obtained. For heat insulation support structure, the results show that it is not obvious to change the distribution law of temperature field, but it is effective to weaken the convection heat transfer between surrounding rock and airflow. In the main airflow area, the rate of heat exchange gradually decreases with the heat exchange becoming more and more sufficient; in boundary layer, the airflow temperature quickly transits from the wall temperature to that of the main airflow area because of intense collisions of airflow masses, so the mechanism of temperature change is different. The surface heat transfer coefficient well reflected the unstable heat-humidity transfer, especially in the beginning of ventilation or at airflow inlet. Therefore, the heat insulation supporting structure is helpful to the auxiliary cooling of high temperature mine.

scholarly journals Numerical simulation of tunnel surrounding rock temperature field

2020 ◽  
Vol 587 ◽  
pp. 012043
Author(s):  
Yansong Wang ◽  
Qunshan Quan ◽  
Yuguo Zhao ◽  
Zhongzhe Zhang ◽  
Xinghong Jiang
Keyword(s):  
Numerical Simulation ◽  
Temperature Field ◽  
Surrounding Rock ◽  
Rock Temperature

scholarly journals Application of Thermal Insulation Gunite Material to the High Geo-Temperature Roadway

2020 ◽  
Vol 2020 ◽  
pp. 1-12
Author(s):  
Junhui Wang ◽  
Zhijun Wan ◽  
Hongwei Zhang ◽  
Dong Wu ◽  
Yuan Zhang ◽  
...  
Keyword(s):  
Temperature Field ◽  
Thermal Insulation ◽  
Thermal Flux ◽  
Temperature Drop ◽  
Surrounding Rock ◽  
Dimensionless Temperature ◽  
Ventilation Network ◽  
Thermal Hazard ◽  
Temperature Disturbance ◽  
Hazard Control

Thermal insulation gunite (TIG) in roadways is an effective method for regional thermal hazard control in mines. The development of mine TIG materials is the foundation of thermal insulation technique. However, some conventional and advanced insulation materials are inapplicable to deep mines which are rather humid with high in situ stress and high geo-temperature. In this study, a kind of fly ash-inorganic mineral TIG material was developed and applied to the modelling of a high geo-temperature roadway. Moreover, the thermal insulation effect of the TIG layer was analyzed, and the temperature field characteristics of the TIG surrounding rock were discussed. Results reveal that (1) the TIG layer has a significant impact on the heat release of the wall and stability of the surrounding rock temperature field; (2) the initial temperature disturbance times, temperature disturbance ranges, and temperature drop rates differ with whether a TIG layer exists or not; (3) after the TIG roadway starts to be ventilated, the thermal flux densities tend to be consistent, which indicates the end of temperature disturbance; besides, the dimensionless temperature shares an exponential relation with the dimensionless radius; and (4) the characteristics of temperature drops vary with the radial positions of the surrounding rock. The research results provide a certain reference for thermal hazard control, temperature prediction, and ventilation network adjustment.

scholarly journals Finite Element Analysis of Surrounding Rock with a Thermal Insulation Layer in a Deep Mine

2020 ◽  
Vol 2020 ◽  
pp. 1-11
Author(s):  
Hao Wang ◽  
Qianyu Zhou
Keyword(s):  
Finite Element ◽  
Thermal Insulation ◽  
Heat Dissipation ◽  
Heat Insulation ◽  
Surrounding Rock ◽  
Insulation Layer ◽  
Distribution Law ◽  
Element Analysis ◽  
Climate Conditions ◽  
Deep Mine

As the main heat source, surrounding rock heat dissipation is a very important factor in the prediction of mine climate conditions, especially in deep high-temperature mines. To reveal the heat control mechanism of surrounding rocks due to the thermal insulation of deep roadways, a mathematical model of the surrounding rocks around deep roadways with heat insulation was established with the finite element method, and a corresponding calculation program was developed. A series of results were determined to show how setting an insulation layer could affect the distribution law of the temperature field within and around tunnels. Therefore, rules of the variation in wall temperature and temperature gradient with thermal conductivity coefficients were obtained within and around tunnels. The heat release capacity of the surrounding rocks of the roadways is significantly reduced after introducing a thermal insulation layer into the roadway design under different schemes; these design schemes were determined by further engineering example analysis. It was found that the heat insulation layer design can cool the surrounding rocks of deep mine roadways.

Model Test Study on Insulator of Cold-Region Tunnel in Northeast China: A Case Study of Gaoling Tunnel

2011 ◽  
Vol 71-78 ◽  
pp. 1870-1874
Author(s):  
Jin Xing Lai ◽  
Cheng Bing Gong ◽  
Yan Song Wang
Keyword(s):  
Temperature Field ◽  
Thermal Insulation ◽  
Model Test ◽  
Similarity Theory ◽  
Decisive Role ◽  
Negative Temperature ◽  
Surrounding Rock ◽  
Systemic Analysis ◽  
Test Study

Based on similarity theory, the systemic analysis for the distribution characteristics of tunnel temperature field in two different working conditions of having no thermal insulation and installing PU as insulator is progressed by using manufactured model test platform in order to realize the tunnel temperature field rule in cold regions with or without thermal insulation and the influence of thermal insulation layout pattern on insulating effect. The results show that the temperature variation conforms to the “tunnel freeze-thaw circle” theory without thermal insulation, and the surrounding rock maintains negative temperature all the time in the low temperature environment; the internal temperature field of surrounding rock plays a decisive role on the surface temperature of surrounding rock, which keeps above 0°C after the layout of thermal insulation with appropriate material and thickness.

scholarly journals Study of Temperature Field Distribution in Topographic Bias Tunnel Based on Monitoring Data

Symmetry ◽  
2021 ◽  
Vol 13 (8) ◽  
pp. 1492
Author(s):  
Tao Zhang ◽  
Lei Nie ◽  
Min Zhang ◽  
Shulin Dai ◽  
Yan Xu ◽  
...  
Keyword(s):  
Temperature Field ◽  
Heat Of Hydration ◽  
Surrounding Rock ◽  
Maximum Temperature ◽  
Rock Temperature ◽  
Topographic Bias ◽  
Short Period ◽  
Annual Minimum Temperature ◽  
Triangular Function ◽  
Secondary Lining

In recent decades, numerous tunnels have been built in the cold region of China. However, the temperature field of topographically biased tunnels in the monsoon freeze zone has not been sufficiently studied. In this study, we monitored the temperature of the surrounding rock in two topographic bias sections of the Huitougou Tunnel and analyzed the results by fitting them to the monitoring results. The results showed that the temperature of the surrounding rock on both sides after tunnel excavation varied periodically in an approximate triangular function. As the distance from the cave wall increased, the annual average temperature of the surrounding rock did not change significantly, the amplitude decreased, and the delay time increased, while the annual maximum temperature decreased, and the annual minimum temperature increased. The heat generated by blasting, the heat of hydration of the primary and secondary lining, and the decorated concrete all caused a significant increase in the temperature of the surrounding rock within 4 m for a short period of time. Both construction and topographic factors led to asymmetry in the distribution of the surrounding rock temperature in different ways. The results of this paper are intended as a reference for other studies on temperature in deviated tunnels.

Monitoring and analysis of the subway tunnel wall temperature and surrounding rock/soil heat absorption ratio

2021 ◽  
Vol 194 ◽  
pp. 107657
Author(s):  
Peng Zhao ◽  
Xiaozhao Li ◽  
Jiajun Liu ◽  
Donghai Zhang ◽  
Hengjun Qiao
Keyword(s):  
Wall Temperature ◽  
Surrounding Rock ◽  
Heat Absorption ◽  
Subway Tunnel ◽  
Tunnel Wall ◽  
Absorption Ratio

Compactness of 𝑀-uniform domains and optimal thermal insulation problems

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Hengrong Du ◽  
Qinfeng Li ◽  
Changyou Wang
Keyword(s):  
Thermal Insulation ◽  
Heat Insulation ◽  
Optimization Problems ◽  
Optimal Shape ◽  
Optimal Heat ◽  
Optimal Shapes ◽  
Stable Solutions ◽  
Uniform Domains

Abstract In this paper, we will consider an optimal shape problem of heat insulation introduced by [D. Bucur, G. Buttazzo and C. Nitsch, Two optimization problems in thermal insulation, Notices Amer. Math. Soc. 64 (2017), 8, 830–835]. We will establish the existence of optimal shapes in the class of 𝑀-uniform domains. We will also show that balls are stable solutions of the optimal heat insulation problem.

Characteristic Law of Borehole Deformation Induced by the Temperature Change in the Surrounding Rock of Deep Coalbed Methane Well

2021 ◽  
pp. 1-18
Author(s):  
Xin Li ◽  
Jie Zhang ◽  
Cuinan Li ◽  
Weilin Chen ◽  
Jingbin He ◽  
...  
Keyword(s):  
Numerical Simulation ◽  
Coalbed Methane ◽  
Linear Equations ◽  
Surrounding Rock ◽  
Experimental Temperature ◽  
Borehole Stability ◽  
Fracture Angle ◽  
High Deformation ◽  
Rock Temperature ◽  
Primary Fracture

Abstract The borehole stability of the coalbed methane (CBM) well has always been vital in deep CBM exploration and development. The borehole instability of the deep CBM well is due to many complicated reasons. The change in the surrounding rock temperature is an important and easily overlooked factor among many reasons. In this research, we used methods that include experiment and numerical simulation to study the characteristic law of the borehole deformation induced by the changes in the surrounding rock temperature of deep CBM well. The experimental results of the stress–strain curves of five sets of experiments show that when the experimental temperature rises from 40 °C to 100 °C, the average stress when coal samples are broken gradually decreases from 81.09 MPa to 72.71 MPa. The proportion of plastic deformation in the entire deformation stage gradually increases from 7.8% to 25.7%. Moreover, the characteristics that some key mechanical parameters of coal samples change with the experimental temperature are fitted, and results show that as the experimental temperature rises from 40 °C to 100 °C, the compressive strength, elastic modulus, and main crack length of coal samples show a gradually decreasing trend. By contrast, the Pois-son's ratio and primary fracture angle show a gradually increasing trend. Moreover, the relativity of the linear equations obtained by fitting is all close to 1, which can accurately reflect the corresponding change trend. Numerical simulation results show that a high temperature of the surrounding rock of the deep CBM well results in a high range of stress concentration on the coal seam borehole and high deformation.

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