Analysis of Frozen Drilling Surrounding Rock Temperature Field about Weakly Cemented Soft Rock

2011 ◽  
Vol 243-249 ◽  
pp. 2375-2381
Author(s):  
Wei Ming Wang ◽  
Lei Wang ◽  
Hai Bin Jia
Keyword(s):  
Temperature Field ◽  
Soft Rock ◽  
Freezing Temperature ◽  
Scientific Basis ◽  
Monitoring Data ◽  
Freezing And Thawing ◽  
Time Prediction ◽  
Rock Temperature ◽  
Temperature Diffusion ◽  
Two Phases

This paper mainly introduced the monitoring scheme of one mine’s wind well in Inner Mongolia. By analyzing the monitoring data at different depth, rules of the freezing temperature field were drawn. Fitting the monitoring data linearly at freezing and thawing phrase respectively, the experience formula of time prediction at the two phases were obtained. Meanwhile the temperature diffusion coefficient of sandstone and mudstone layers were revised, which can provide scientific basis for some similiar shaft construction.

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.

Investigation of the Constitutive Modle of Saturated Frozen Soil Based on Damage

2013 ◽  
Vol 353-356 ◽  
pp. 221-224
Author(s):  
Shuang Zhang ◽  
Chun An Tang ◽  
Lei Li ◽  
Shuai Li
Keyword(s):  
Phase Transition ◽  
Temperature Field ◽  
Stress Field ◽  
Constitutive Model ◽  
Internal Structure ◽  
Damage Mechanics ◽  
Frozen Soil ◽  
Unfrozen Water ◽  
Freezing And Thawing ◽  
Water Field

Saturated frozen soil is composed of soil, unfrozen water and ice, whose subgrade deformation is due to the weakened of internal structure which coursed by damage of the materials in the process of the cycle of freezing and thawing. Considing of the heterogeneity of saturated frozen soil and the phase transition between water and ice, and using of the damage mechanics theory, thermodynamics theory, filtration mechanics theory, a constitutive model of saturated frozen soil is setted up, which is of the coupfing problem of temperature field, water field and stress field. The rationality and validity of the model is verified by the experiment. It is also provided a new method for the study of frozen soil.

scholarly journals Study on the Formation Law of the Freezing Temperature Field of Freezing Shaft Sinking under the Action of Large-Flow-Rate Groundwater

2019 ◽  
Vol 2019 ◽  
pp. 1-20 ◽  
Author(s):  
Bin Wang ◽  
Chuan-xin Rong ◽  
Jian Lin ◽  
Hua Cheng ◽  
Hai-bing Cai
Keyword(s):  
Temperature Field ◽  
Groundwater Flow ◽  
Flow Velocity ◽  
Flow Rate ◽  
Freezing Temperature ◽  
Freezing Process ◽  
Flow Rates ◽  
Porosity Reduction ◽  
Shaft Sinking ◽  
Large Flow

Taking into account moisture migration and heat change during the soil freezing process, as well as the influence of absolute porosity reduction on seepage during the freezing process, we construct a numerical model of hydrothermal coupling using laws of conservation of energy and mass. The model is verified by the results of large-scale laboratory tests. By applying the numerical calculation model to the formation of artificial shaft freezing temperature fields under the action of large-flow groundwater, we conclude that groundwater with flow rates of less than 5 m/d will not have a significant impact on the artificial freezing temperature field. The maximum flow rates that can be handled by single-row freezing pipes and double-row freezing pipes are 10 m/d and 20 m/d, respectively, during the process of freezing shaft sinking. By analyzing the variation of groundwater flow rate during freezing process, we find that the groundwater flow velocity can reach 5–7 times the initial flow velocity near the closure moment of the frozen wall. Finally, in light of the action characteristics of groundwater on the freezing temperature field, we make suggestions for optimal pipe and row spacing in freezing pipe arrangement.

scholarly journals Effects of Cyclic Freeze–Thaw on the Steel Bar Reinforced New-To-Old Concrete Interface

Molecules ◽  
2020 ◽  
Vol 25 (5) ◽  
pp. 1251
Author(s):  
Tao Luo ◽  
Chi Zhang ◽  
Xiangtian Xu ◽  
Yanjun Shen ◽  
Hailiang Jia ◽  
...  
Keyword(s):  
Compressive Strength ◽  
Shear Strength ◽  
Concrete Structures ◽  
Freezing Temperature ◽  
Frost Damage ◽  
Freezing And Thawing ◽  
Shear Properties ◽  
Freeze Thaw ◽  
Steel Bar ◽  
Concrete Interface

Frost damage of concrete has significant effects on the safety and durability of concrete structures in cold regions, and the concrete structures after repair and reinforcement are still threatened by cyclic freezing and thawing. In this study, the new-to-old concrete interface was reinforced by steel bar. The shear strength of the new-to-old concrete interface was tested after the new-to-old combination was subjected to cyclic freeze–thaw. The effects of the diameter of the steel bar, the compressive strength of new concrete, the number of freeze–thaw cycles and the freezing temperatures on the shear properties of new-to-old concrete interface were studied. The results showed that, in a certain range, the shear strength of the interface was proportional to the diameter of the steel bar and the strength of the new concrete. Meanwhile, the shear strength of the reinforced interface decreased with the decreasing of the freezing temperature and the increasing of the number of freeze–thaw cycles.

Influence de la température minimale du cycle de gel–dégel sur la détérioration du béton par écaillage en présence de sels fondants

1996 ◽  
Vol 23 (3) ◽  
pp. 595-601
Author(s):  
J. Marchand ◽  
M. Pigeon ◽  
L. Boisvert
Keyword(s):  
Test Procedure ◽  
Air Entrainment ◽  
Freezing Temperature ◽  
Freezing And Thawing ◽  
Concrete Mixtures ◽  
Conditioning Period ◽  
Binder Ratio ◽  
Freezing Cycle ◽  
Air Void ◽  
Scaling Resistance

Eight different concrete mixtures were prepared to investigate the influence of the minimum temperature of the freezing and thawing cycle on scaling deterioration due to deicer salt. In addition to the two minimum temperatures studied (−18 and −9 °C), test variables included the type of binder (with or without silica fume), the water/binder ratio (0.35 or 0.45), the characteristics of the air-void network (with or without air entrainment), and the drying temperature during the conditioning period prior to the scaling test (20, 40, or 110 °C). The scaling resistance to deicer salt of all concrete mixtures was assessed according to the prescriptions of the ASTM C672 test procedure using a 3 % NaCl solution. Test results indicate that a reduction of the minimal temperature from −9 to −18 °C significantly increases the scaling deterioration of concrete due to deicer salt. Key words: freezing cycle, scaling resistance, minimal freezing temperature, deicer salts.

Simple method for preparing a concentration gradient of serum components by freezing and thawing

1991 ◽  
Vol 37 (7) ◽  
pp. 1225-1229 ◽  
Author(s):  
Tetsuo Hirano ◽  
Toshiaki Yoneyama ◽  
Hiroko Matsuzaki ◽  
Takainitsu Sekine
Keyword(s):  
Concentration Gradient ◽  
Clinical Laboratory ◽  
Freezing Temperature ◽  
Test Results ◽  
Freezing And Thawing ◽  
Serum Samples ◽  
Simple Method ◽  
Gradient Formation ◽  
Repeated Freezing ◽  
Serum Components

Abstract We created a simple method for obtaining a series of successively more-concentrated samples from a serum without changing the ratio of its components. We froze a pooled serum and then allowed it to thaw undisturbed. The serum components formed a gradient of increasing concentration from the top of the sample to the bottom. We found that (a) in test results, each fraction of serum in the gradient showed almost the same relative concentrations of components (i.e., inorganic and organic compounds, proteins, metals, and hormones), irrespective of atomic or molecular mass; (b) the concentration gradient depended on the thawing temperature but not on the freezing temperature; (c) when we thawed the frozen sample with centrifugation, the slope of the concentration gradient increased with increasing centrifugal force; (d) when the thawed sample was fractionated into 10 fractions from the top to the bottom, the original serum concentration was always maintained between the sixth and seventh fractions from the top; and (e) the concentration gradient became steeper with repeated freezing and thawing. By using this method, one can easily prepare serum samples at gradients of concentration useful in the clinical laboratory, although the mechanism of gradient formation is still unclear.

RELEASE OF ENZYMES FROM RAT LIVER MITOCHONDRIA BY FREEZING

1965 ◽  
Vol 43 (11) ◽  
pp. 1787-1798 ◽  
Author(s):  
C. V. Lusena
Keyword(s):  
Glutamate Dehydrogenase ◽  
Membrane Structure ◽  
Sucrose Concentration ◽  
Freezing Temperature ◽  
Liver Mitochondria ◽  
Rat Liver Mitochondria ◽  
Freezing Damage ◽  
Freezing And Thawing ◽  
High Sucrose Concentration ◽  
High Sucrose

Glutamate and 3-hydroxybutyrate dehydrogenase activities were used to estimate freezing damage to mitochondria.Freezing damage occurred in mitochondria by two steps: one was rapid and involved changes in membrane structure to expose 3-hydroxybutyrate dehydrogenase with concomitant release of glutamate dehydrogenase; the other was a slow extraction of glutamate dehydrogenase. The effect of freezing and thawing was very similar to the effect of exposure to high sucrose concentration and redilution. The data indicate that freezing temperature not only determined the sucrose concentration but also regulated the diffusion of sucrose. A combination of effects, of sucrose concentration and of diffusion, resulted in maximum damage at about −15 °C, while below −40 °C no damage was detectable.

scholarly journals Research on the Temperature Field and Frost Heaving Law of Massive Freezing Engineering in Coastal Strata

2021 ◽  
Vol 2021 ◽  
pp. 1-12
Author(s):  
Chaochao Zhang ◽  
Dongwei Li ◽  
Junhao Chen ◽  
Guanren Chen ◽  
Chang Yuan ◽  
...  
Keyword(s):  
Temperature Field ◽  
Three Dimensional ◽  
Element Model ◽  
Freezing Temperature ◽  
Frozen Soil ◽  
Physical Parameters ◽  
Frost Heaving ◽  
Soil Frost ◽  
Dimensional Finite Element ◽  
Three Dimensional Finite Element

In this study, based on the background of massive freezing engineering in coastal strata, the thermal physical parameters and some freezing laws of soil were obtained through soil thermal physical tests and frozen soil frost heaving tests. When the freezing temperatures were −5°C, −10°C, −15°C, and −20°C, the frost heaving rates of the soil were 0.53%, 0.95%, 1.28%, and 1.41%, and the frost heaving forces of the soil were 0.37 MPa, 0.46 MPa, 0.59 MPa, and 0.74 MPa, respectively. In the range of test conditions, the frost heaving rate and the frost heaving force of the soil increased with the decrease of the freezing temperature, and the relationship was roughly linear with the temperature. The entire cooling process could be roughly divided into three stages: active freezing stage, attenuation cooling stage, and stability stage. The range of the frozen soil expansion did not increase linearly with the decrease of the freezing temperature, and there was a limit radius for the frozen soil expansion. A three-dimensional finite element model was established to simulate the temperature field and frost heaving of the soil under the on-site working conditions. The entire frost heaving process could be roughly divided into two stages. The calculated temperature values and the frost heaving force values were compared with the on-site measured values, and the results verified that the numerical calculation could accurately reflect the temperature field and frost heaving law of the formation.

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