scholarly journals A Study on the Heat Transfer of Surrounding Rock-Supporting Structures in High-Geothermal Tunnels

2020 ◽  
Vol 10 (7) ◽  
pp. 2307
Author(s):  
Mingnian Wang ◽  
Yunpeng Hu ◽  
Dagang Liu ◽  
Cheng Jiang ◽  
Qiling Wang ◽  
...  
Keyword(s):  
Temperature Distribution ◽  
Quadratic Function ◽  
Surrounding Rock ◽  
Curing Temperature ◽  
Rock Temperature ◽  
Lining Structure ◽  
Tunnel Design ◽  
The Impact ◽  
Research And Design ◽  
Initial Rock

The temperature distribution is one of the most vital parameters which should be fully considered in high geothermal tunnel design. For the purpose of studying the impact of temperature disturbance caused by construction on temperature distribution of surrounding rock and lining structure in a high geothermal tunnel, a new finite difference model for temperature prediction was proposed. Based on the abundant field test results, forecast analysis for the research of a high geothermal tunnel in this paper is made. The results indicate that the temperature of the surrounding rock near the tunnel sidewall decreases obviously in the first 14 days while that of the surrounding rock far away is stable after tunnel excavation, and the rock temperature showed three ways of change: undulate type (<2 m), decline type (2–5 m) and stable type (>5 m). There is a linear relationship between the initial rock temperature and the released heat of the surrounding rock. The radius of the heat-adjusting layer and the initial rock temperature presents a quadratic function relation. The lining concrete actually cures under the variable high-temperature environment and the real curing temperature decreases with time and becomes stable seven days later. The results would contribute to providing support for high geothermal tunnel research and design.

Analysis of Temperature Field of the Tunnel Surrounding Rock in Cold Regions

2013 ◽  
Vol 753-755 ◽  
pp. 745-749 ◽  
Author(s):  
Hui Mei Zhang ◽  
Hai Bo Cao ◽  
Meng Jun Zhang
Keyword(s):  
Temperature Field ◽  
Temperature Distribution ◽  
Great Influence ◽  
Transient Heat Conduction ◽  
Surrounding Rock ◽  
Tunnel Wall ◽  
Cold Regions ◽  
Freeze Thaw ◽  
Tunnel Design ◽  
Heat Conduction Differential Equation

Freeze-thaw disaster is an outstanding problem of geotechnical engineering in cold regions. The temperature field of tunnel surrounding rock in Qilian mountain Osaka hill was calculated according to the transient heat conduction differential equation, meanwhile the freezing conditions of tunnel surrounding rock was forecasted and analyzed after its opening. The study shows that the freeze-thaw environment has a great influence on the temperature distribution of surrounding rock. The tunnel wall and near the mouth of the cave area are more susceptible to the influence of the open ground temperature and air convection, thus the temperature changes violently , but the temperature distribution in surrounding rock tends to be dynamic stable equilibrium as time goes on. The research results can provide a reference for tunnel design and construction in cold regions.

A Study on Temperature Distribution of Surrounding Rock and Mechanical Characteristics of Lining of Monglian Tunnel under High Geothermal

2011 ◽  
Vol 255-260 ◽  
pp. 2594-2600 ◽  
Author(s):  
Bo Liang ◽  
Ning Yu Zhao
Keyword(s):  
Heat Transfer ◽  
Temperature Distribution ◽  
Mechanical Characteristics ◽  
Surrounding Rock ◽  
Construction Technology ◽  
Tunnel Design ◽  
Rock Exposure ◽  
The Relationship ◽  
Blast Furnace Cement ◽  
Design And Construction

To solve design and construction problems of Monglian tunnel under high geothermal, based on the change rules of thermal parameters of surrounding rock and lining during excavation period, this paper analyzed the temperature distribution, heat transfer in tunnel and interaction between lining and surrounding rock, then by using numerical simulation, the relationship between temperature field and mechanical characteristics of lining and surrounding rock was discussed. Finally, the methods of using blast furnace cement, utilizing wet spraying concrete construction technology, and making surrounding rock exposure time as short as possible to reduce damages high temperature caused was proposed. The result can provide experience in similar tunnel design and construction.

scholarly journals Research and Analysis on the Supporting Structure of the Second Lining of the Tunnel in the Phyllite Stratum

2020 ◽  
Vol 198 ◽  
pp. 02014
Author(s):  
Wei Zhiquan ◽  
Huang Baisheng ◽  
Yang Lu ◽  
Wei Yonghao ◽  
Qiu Jianqiao
Keyword(s):  
Plastic Zone ◽  
Surrounding Rock ◽  
Supporting Structure ◽  
Geological Conditions ◽  
Lining Structure ◽  
Calculation Results ◽  
Main Period ◽  
Secondary Lining ◽  
The Stability ◽  
The Impact

The reasonable construction of the secondary lining structure of the tunnel is an important link to ensure the stability of the surrounding rock of the tunnel. Taking a phyllite stratum tunnel project in Jiangxi as the background, the Flac3D finite difference software was used to numerically simulate and analyze the supporting structure of the secondary lining. The impact of support timing on surrounding rock stress. The calculation results show that with the progress of the construction step, the main period of the displacement of the vault is after the excavation of the upper section of the tunnel before the upper section support; The plastic zone of the surrounding rock changes obviously, especially above the tunnel, and finally the plastic zone develops to the ground; the stress of the surrounding rock shows a decreasing trend with the increase of the time of the secondary lining. The research results can provide certain guiding significance for the construction of the second lining of the tunnel under similar geological conditions.

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 Influence of CFRC Insulating Plates on Spark Plasma Sintering Process

Metals ◽  
2021 ◽  
Vol 11 (3) ◽  
pp. 393
Author(s):  
Alexander M. Laptev ◽  
Jürgen Hennicke ◽  
Robert Ihl
Keyword(s):  
Temperature Distribution ◽  
Spark Plasma Sintering ◽  
Energy Demand ◽  
Composite Powders ◽  
Fem Method ◽  
Plasma Sintering ◽  
Axial Temperature ◽  
Spark Plasma ◽  
Power And Energy ◽  
The Impact

Spark Plasma Sintering (SPS) is a technology used for fast consolidation of metallic, ceramic, and composite powders. The upscaling of this technology requires a reduction in energy consumption and homogenization of temperature in compacts. The application of Carbon Fiber-Reinforced Carbon (CFRC) insulating plates between the sintering setup and the electrodes is frequently considered as a measure to attain these goals. However, the efficiency of such a practice remains largely unexplored so far. In the present paper, the impact of CFRC plates on required power, total sintering energy, and temperature distribution was investigated by experiments and by Finite Element Modeling (FEM). The study was performed at a temperature of 1000 °C with a graphite dummy mimicking an SPS setup. A rather moderate influence of CFRC plates on power and energy demand was found. Furthermore, the cooling stage becomes considerably longer. However, the application of CFRC plates leads to a significant reduction in the axial temperature gradient. The comparative analysis of experimental and modeling results showed the good capability of the FEM method for prediction of temperature distribution and required electric current. However, a discrepancy between measured and calculated voltage and power was found. This issue must be further investigated, considering the influence of AC harmonics in the DC field.

scholarly journals Prediction of factors affecting activation of soil erosion by mathematical modeling at pedon scale under laboratory conditions

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Saeed Shojaei ◽  
Zahra Kalantari ◽  
Jesús Rodrigo-Comino
Keyword(s):  
Soil Loss ◽  
Rainfall Intensity ◽  
Quadratic Function ◽  
Interactive Effects ◽  
Soil Protection ◽  
Single Factor ◽  
Rainfall Events ◽  
Rainfall Duration ◽  
The Impact ◽  
Runoff Production

AbstractSoil degradation due to erosion is a significant worldwide problem at different spatial (from pedon to watershed) and temporal scales. All stages and factors in the erosion process must be detected and evaluated to reduce this environmental issue and protect existing fertile soils and natural ecosystems. Laboratory studies using rainfall simulators allow single factors and interactive effects to be investigated under controlled conditions during extreme rainfall events. In this study, three main factors (rainfall intensity, inclination, and rainfall duration) were assessed to obtain empirical data for modeling water erosion during single rainfall events. Each factor was divided into three levels (− 1, 0, + 1), which were applied in different combinations using a rainfall simulator on beds (6 × 1 m) filled with soil from a study plot located in the arid Sistan region, Iran. The rainfall duration levels tested were 3, 5, and 7 min, the rainfall intensity levels were 30, 60, and 90 mm/h, and the inclination levels were 5, 15, and 25%. The results showed that the highest rainfall intensity tested (90 mm/h) for the longest duration (7 min) caused the highest runoff (62 mm3/s) and soil loss (1580 g/m2/h). Based on the empirical results, a quadratic function was the best mathematical model (R2 = 0.90) for predicting runoff (Q) and soil loss. Single-factor analysis revealed that rainfall intensity was more influential for runoff production than changes in time and inclination, while rainfall duration was the most influential single factor for soil loss. Modeling and three-dimensional depictions of the data revealed that sediment production was high and runoff production lower at the beginning of the experiment, but this trend was reversed over time as the soil became saturated. These results indicate that avoiding the initial stage of erosion is critical, so all soil protection measures should be taken to reduce the impact at this stage. The final stages of erosion appeared too complicated to be modeled, because different factors showed differing effects on erosion.

Research on the Impact of Temperature on the Softening Point of SBS Modified Asphalt

2013 ◽  
Vol 365-366 ◽  
pp. 978-982
Author(s):  
Xiao Wei Feng ◽  
De Wen Zhang
Keyword(s):  
Softening Point ◽  
Heating Temperature ◽  
Road Construction ◽  
Curing Temperature ◽  
Important Indicator ◽  
Modified Asphalt ◽  
Influence Of Temperature On ◽  
Sbs Modified Asphalt ◽  
The Impact ◽  
Initial Heating

The softening point of modified asphalt is an extremely important indicator to evaluate the high-temperature performance; its the temperature of modified asphalt sample emerging shear deformation under the action of certain shear stress according to the specific heating rate. Its found that in the actual construction and testing, different temperature conditions has a larger impact on the softening point of the modified asphalt, which has adverse affect on road construction. This paper studied and researched the influence of temperature on modified asphalt softening point indicators from the different test temperature, including packing compact temperature, scraper temperature in removal of asphalt that above test mode, standing temperature, curing temperature and initial heating temperature before test.

Effect of Inlet Configuration on Moderator Velocity and Temperature Distribution Inside the Calandria of a Heavy Water Reactor

2008 ◽  
Author(s):  
Abhijeet Mohan Vaidya ◽  
Naresh Kumar Maheshwari ◽  
Pallippattu Krishnan Vijayan ◽  
Dilip Saha ◽  
Ratan Kumar Sinha
Keyword(s):  
Temperature Distribution ◽  
Impact Velocity ◽  
Heavy Water ◽  
Computational Study ◽  
Water Reactor ◽  
Heavy Water Reactor ◽  
The Impact

Computational study of the moderator flow in calandria vessel of a heavy water reactor is carried out for three different inlet nozzle configurations. For the computations, PHOENICS CFD code is used. The flow and temperature distribution for all the configurations are determined. The impact of moderator inlet jets on adjacent calandria tubes is studied. Based on these studies, it is found that the inlet nozzles can be designed in such a way that it can keep the impact velocity on calandria tubes within limit while keeping maximum moderator temperature well below its boiling limit.

Preparation and properties of novel sulfonic graphene oxide–epoxy resin nanocomposites by resin transfer molding process

2016 ◽  
Vol 51 (9) ◽  
pp. 1197-1208 ◽  
Author(s):  
Wei Li ◽  
Hongyu Li ◽  
Xinguo Yang ◽  
Wei Feng ◽  
Hongyun Huang
Keyword(s):  
Graphene Oxide ◽  
Impact Strength ◽  
Epoxy Resin ◽  
Curing Temperature ◽  
Flexural Property ◽  
Oxide Content ◽  
Molding Process ◽  
One Pot ◽  
Epoxy Resin Nanocomposites ◽  
The Impact

This paper reported a facile one-pot strategy for fabrication of sulfonic graphene oxide–epoxy resin nanocomposites. The rheological and thermal properties were employed to characterize the viscosity and the curing temperature of epoxy resin. Fourier transform infrared spectra for sulfonic graphene oxide and nanocomposites indicated that the sulfonic graphene oxide contains chemical cross-linking responsible for better interactions with the epoxy resin. The state of dispersion was evaluated at different scales by still picture camera and scanning electron microscopy (SEM). Tensile property tests indicated that the tensile strength and elasticity modulus of sulfonic graphene oxide–epoxy resin nanocomposites decreased slowly with increasing of sulfonic graphene oxide content. The critical flexural property and impact strength of epoxy resin filled with sulfonic graphene oxide nanocomposites were measured. The content, size, and dispersion state of sulfonic graphene oxide were examined. It was found that the content of sulfonic graphene oxide has greater impact on both flexural property and impact strength of nanocomposites compared with other conditions. For instance, the impact strength increased by 113.0% and the flexural strength and modulus increased by 39.3% and 55.7% using 1 wt.% sulfonic graphene oxide as compared to neat epoxy resin.

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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