scholarly journals Freezing Temperature Field of FSPR under Different Pipe Configurations: A Case Study in Gongbei Tunnel, China

2021 ◽  
Vol 2021 ◽  
pp. 1-13
Author(s):  
Yin Duan ◽  
Chuanxin Rong ◽  
Hua Cheng ◽  
Haibing Cai ◽  
Wei Long
Keyword(s):  
Temperature Field ◽  
Freezing Temperature ◽  
Cooling Capacity ◽  
Frozen Soil ◽  
Construction Technology ◽  
Scaled Model ◽  
The Difference ◽  
Improved Design ◽  
Lower Temperature ◽  
Time Required

As a new tunnel presupport construction technology, the freeze-sealing pipe roof method (FSPR) has been successfully applied to the Gongbei Tunnel Project for the first time in China. To overcome the practical difficulties of this new method in the freezing construction process, such as welding difficulties of the profiled freezing tube, refrigerant leakage, and long construction period, based on the principle of an equal cooling capacity, an improved design of freezing tube was proposed. By designing three different pipe configurations and using scaled model tests and numerical simulation, the feasibility of the improvement and the difference in the freezing temperature field were studied. The research results show that the improved design with double circular freezing tubes exhibited a lower temperature and a higher cooling rate during the test, and the time required to meet the freezing design requirements was significantly shortened. Finally, a composite structure of “pipe roof and frozen soil curtain” with a better carrying capacity and water sealing performance was formed. It was recommended to strengthen the temperature monitoring at the pipe wall in the preliminary stage of the freezing construction to ensure the water sealing effect between the pipes. In the later stage, attention should be paid to monitoring the thickness of the frozen curtain and reducing excessive frost heave through technical means such as cooling capacity control. The improvement and configurations proposed in this research could effectively replace profiled freezing tubes in the original project, better adapt to horizontal freezing projects of similar curved tunnels, achieve the freezing goal faster, and provide a reference for the promotion of the FSPR.

scholarly journals Experimental and Numerical Investigation on Improved Design for Profiled Freezing-tube of FSPR

Processes ◽  
2020 ◽  
Vol 8 (8) ◽  
pp. 992
Author(s):  
Yin Duan ◽  
Chuanxin Rong ◽  
Hua Cheng ◽  
Haibing Cai ◽  
Zongjin Wang ◽  
...  
Keyword(s):  
Vertical Direction ◽  
Calculation Model ◽  
Frozen Soil ◽  
Working Environment ◽  
Scaled Model ◽  
Ground Freezing ◽  
Artificial Ground Freezing ◽  
Improved Design ◽  
Lower Temperature ◽  
The Right

The freeze-sealing pipe roof (FSPR) method, which combines the pipe roof method (PRM) with the artificial ground freezing (AGF) method, has been successfully utilized for the first time in the Gongbei Tunnel Project in China. During the construction process, there have been practical problems such as difficulty in welding of the profiled freezing-tube, easy leakage of refrigerant, and working environment pollution, which bring difficulties to the tunnel construction and may affect the further promotion of this new method in the future. To address these problems, a method of placing double circular freezing-tubes on the inner wall of the hollow pipe and wrapped with cement mortar was put forward to replace the welding profiled freezing-tube in the actual project. By designing a scaled model test, the feasibility and freezing effect of this improved design were verified. The corresponding numerical calculation model was established to study the distribution characteristics and differences of temperature field under two different configurations. The research results show that the Configuration 2, with the improved design, presents a lower temperature and a higher cooling rate; the limiting-tube could limit the excessive development of the frozen soil wall within a certain range, to avoid the adverse impact of frost heave on the ground building structure. Under the premise of meeting the design requirements for freezing, the freezing time of Configuration 2 at the centerline between the pipes and the vertical line of the hollow pipe is 33% and 46% shorter than that of Configuration 1, respectively. Finally, the average thickness of the frozen soil wall at the right side of the hollow pipe, the vertical direction of the hollow pipe, and between the pipes increased 33%, 17%, and 13% in Configuration 2, respectively. The improved design proposed in this paper is not only more convenient in production and installation but is also demonstrated to provide improved freezing effects, providing a strong guarantee for the further popularization and application of the freeze-sealing pipe roof method.

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.

scholarly journals Analysis of the Development Characteristics and Influencing Factors of Freezing Temperature Field in the Cross Passage

2021 ◽  
Vol 2021 ◽  
pp. 1-11
Author(s):  
Yan Zhuang ◽  
Junhao Chen ◽  
Jian Zhang ◽  
Jianlin Wang ◽  
Han Li
Keyword(s):  
Wall Thickness ◽  
Completion Time ◽  
Measurement Data ◽  
Freezing Temperature ◽  
Cooling Capacity ◽  
Deep Soil ◽  
Sandy Silt ◽  
The Cross ◽  
The Difference ◽  
Silt Layer

Based on the analysis of the temperature measurement data of the Shanghai Metro Line 15 cross passage freezing project, it was found that the gray silt layer of cross passage No. 2 outperforms that of cross passage No. 1 on the freezing effect, which is mainly attributed to the large loss of cooling capacity in the latter passage. Within the same stratum, the soil temperature at the duct piece is higher than that of the deep soil. When the soil freezes for 45 days, the temperatures of the sandy silt and gray silt layers of the same cross passage drop to −8.25°C and −6.91°C, respectively, indicating that the freezing effect of the sandy silt layer is better than that of the gray silt layer. Moreover, simulations were performed for deviation freezing pipes, nondeviation freezing pipes, and different freezing pipe diameters in the cross passage No. 1, respectively. It was found that the maximum difference of the closure completion time between the deviation and nondeviation freezing pipes is 6 days. Furthermore, for deviation freezing pipes and nondeviation freezing pipes at the center of the cross passage, the minimum difference in the freezing wall thickness reduces from 0.45 mm after 20 days of freezing to 0.06 mm after 45 days of freezing, indicating that the difference in the freezing wall thickness gradually weakens as freezing develops gradually. The deviation freezing pipe increases the spacing of freezing pipes in the deep soil. As the pipe spacing increases, the influence of the pipe diameter on the closure completion time of the freezing wall decreases.

Numerical Simulation of Solidification Process for a Machine Tool Bed

2011 ◽  
Vol 675-677 ◽  
pp. 987-990
Author(s):  
Ling Tang ◽  
Xu Dong Wang ◽  
Hai Jing Zhao ◽  
Man Yao
Keyword(s):  
Heat Transfer ◽  
Temperature Field ◽  
Temperature Distribution ◽  
Machine Tool ◽  
Computation Time ◽  
Solidification Process ◽  
Field Calculation ◽  
Original Design ◽  
Calculation Results ◽  
Improved Design

In this paper, the flow, heat transfer and stress during solidification process of the machine tool bed weighed about 2.5ton that has been optimized by structural topologymethod, was calculated with ProCAST software, and the causes of the crack forming in the casting of the machine tool bed was analysed. According to the calculation results, the structural design of the local part where cracks tends to form has been improved, and the heat transfer and the stress are calculated again. By comparing the temperature field with filling of molten cast iron and without filling, it has been found that there was little effect of filling on the results of temperature distribution of the cast, therefore the effect of filling can be ignored in the following temperature field calculation to save computation time. The model has been simplified in the stress field calculation with considering the complexity of the machine tool bed and the cost of computation. Then, the merits and demerits of the original design and the improved design are compared and analyzed depending on the calculated temperature and stress results. It is suggested that the improved one could get a more uniform temperature distribution and then the trend of the crack occurring can be greatly reduced. These results could provide a guide for the actual casting production, achieving the scientific control of the production of castings, ensuring the quality of the castings.

scholarly journals A Fast Retrieval of Cloud Parameters Using a Triplet of Wavelengths of Oxygen Dimer Band around 477 nm

2021 ◽  
Vol 13 (1) ◽  
pp. 152
Author(s):  
Haklim Choi ◽  
Xiong Liu ◽  
Gonzalo Gonzalez Abad ◽  
Jongjin Seo ◽  
Kwang-Mog Lee ◽  
...  
Keyword(s):  
Scattered Light ◽  
Trace Gas ◽  
Retrieval Algorithm ◽  
The Novel ◽  
Cloud Parameters ◽  
Retrieval Scheme ◽  
The Difference ◽  
The Look ◽  
Time Required ◽  
Cloud Top Pressure

Clouds act as a major reflector that changes the amount of sunlight reflected to space. Change in radiance intensity due to the presence of clouds interrupts the retrieval of trace gas or aerosol properties from satellite data. In this paper, we developed a fast and robust algorithm, named the fast cloud retrieval algorithm, using a triplet of wavelengths (469, 477, and 485 nm) of the O2–O2 absorption band around 477 nm (CLDTO4) to derive the cloud information such as cloud top pressure (CTP) and cloud fraction (CF) for the Geostationary Environment Monitoring Spectrometer (GEMS). The novel algorithm is based on the fact that the difference in the optical path through which light passes with regard to the altitude of clouds causes a change in radiance due to the absorption of O2–O2 at the three selected wavelengths. To reduce the time required for algorithm calculations, the look-up table (LUT) method was applied. The LUT was pre-constructed for various conditions of geometry using Vectorized Linearized Discrete Ordinate Radiative Transfer (VLIDORT) to consider the polarization of the scattered light. The GEMS was launched in February 2020, but the observed data of GEMS have not yet been widely released. To evaluate the performance of the algorithm, the retrieved CTP and CF using observational data from the Global Ozone Monitoring Experiment-2 (GOME-2), which cover the spectral range of GEMS, were compared with the results of the Fast Retrieval Scheme for Clouds from the Oxygen A band (FRESCO) algorithm, which is based on the O2 A-band. There was good agreement between the results, despite small discrepancies for low clouds.

scholarly journals Experimental Study of the Space–Time Effect of a Double-Pipe Frozen Curtain Formation with Different Groundwater Velocities

Energies ◽  
2021 ◽  
Vol 14 (13) ◽  
pp. 3830
Author(s):  
Shicheng Sun ◽  
Chuanxin Rong ◽  
Hua Cheng ◽  
Bin Wang ◽  
Xiaogang Jiang ◽  
...  
Keyword(s):  
Freezing Temperature ◽  
Physical Model Test ◽  
Sand Layer ◽  
Test Results ◽  
Groundwater Velocity ◽  
Test Platform ◽  
The Difference ◽  
Freezing Test ◽  
Double Pipe ◽  
Thermal Physical Properties

Groundwater velocity has significant effects on the formation of a frozen curtain during freezing. In order to study the influence of the velocity on a frozen curtain, a large physical model test platform was established for double-pipe freezing. Based on this platform, freezing tests for different velocities were carried out. Quartz sand was selected as a similar material. The freezing temperature of the saturated sand layer was found by analyzing the results of the nuclear magnetic resonance (NMR). Based on the study of the thermal physical properties of the sand layer, the freezing test results were analyzed, and the results showed that the flow led to the differential development of the temperature between the upstream and downstream sections of the freezing pipes. Moreover, the larger the velocity, the greater the difference. The flow prolonged the overlapping time of the frozen curtains. Additionally, the flow slowed down the development of the frozen curtain area and the frozen curtain thickness. The larger the flow velocity, the greater the inhibition of the flow on the development of the frozen curtain. The test results can provide more references for the design and construction of freezing engineering with flowing groundwater.

Algorithms for Density, Potential Temperature, Conservative Temperature, and the Freezing Temperature of Seawater

2006 ◽  
Vol 23 (12) ◽  
pp. 1709-1728 ◽  
Author(s):  
David R. Jackett ◽  
Trevor J. McDougall ◽  
Rainer Feistel ◽  
Daniel G. Wright ◽  
Stephen M. Griffies
Keyword(s):  
Thermal Expansion ◽  
Equation Of State ◽  
Thermodynamic Potential ◽  
Potential Temperature ◽  
Inverse Function ◽  
Freezing Temperature ◽  
Ocean Models ◽  
The Difference ◽  
New Equation ◽  
Density Equation

Abstract Algorithms are presented for density, potential temperature, conservative temperature, and the freezing temperature of seawater. The algorithms for potential temperature and density (in terms of potential temperature) are updates to routines recently published by McDougall et al., while the algorithms involving conservative temperature and the freezing temperatures of seawater are new. The McDougall et al. algorithms were based on the thermodynamic potential of Feistel and Hagen; the algorithms in this study are all based on the “new extended Gibbs thermodynamic potential of seawater” of Feistel. The algorithm for the computation of density in terms of salinity, pressure, and conservative temperature produces errors in density and in the corresponding thermal expansion coefficient of the same order as errors for the density equation using potential temperature, both being twice as accurate as the International Equation of State when compared with Feistel’s new equation of state. An inverse function relating potential temperature to conservative temperature is also provided. The difference between practical salinity and absolute salinity is discussed, and it is shown that the present practice of essentially ignoring the difference between these two different salinities is unlikely to cause significant errors in ocean models.

Heat Effect Analysis of Buried Oil Pipeline in the Qinghai-Tibet Plateau

2014 ◽  
Vol 501-504 ◽  
pp. 211-217
Author(s):  
Wei Bo Liu ◽  
Wen Bing Yu ◽  
Xin Yi ◽  
Lin Chen
Keyword(s):  
Temperature Field ◽  
Frozen Soil ◽  
Operating Conditions ◽  
Tibet Plateau ◽  
Soil Mechanic ◽  
Insulation Layer ◽  
Effect Analysis ◽  
Oil Pipeline ◽  
Permafrost Table ◽  
Qinghai Tibet Plateau

The Geermu-Lasa oil pipeline was located in the Qinghai-Tibet Plateau permafrost regions. The building and operating of pipeline will change the temperature field of soil around it, which can lead to changes of frozen soil mechanic properties, and this will induces deformation or even fracture of pipeline. These phenomena will affect the normal transportation of oil. In this paper, temperature field around the pipelines were analyzed due to different pipe diameters and different insulation layer thicknesses in the way of finite element method. The rule of thawing and freezing of soil around the pipeline in an annual cycle was obtained. Artificial permafrost table variations under the pipeline were also obtained due to different operating conditions. For 30cm diameter pipeline with 7cm insulation layer, its artificial permafrost table depth change value is just 0.48m after 30-year running. These analysis results can provide references to the construction of the new Geermu-Lasa oil pipeline.

COLD HARDENING AND DEHARDENING RESPONSES IN WINTER WHEAT AND WINTER BARLEY

1975 ◽  
Vol 55 (2) ◽  
pp. 529-535 ◽  
Author(s):  
M. K. POMEROY ◽  
C. J. ANDREWS ◽  
G. FEDAK
Keyword(s):  
Winter Wheat ◽  
Cold Hardiness ◽  
Maximum Level ◽  
Freezing Temperature ◽  
Triticum Aestivum L ◽  
Winter Barley ◽  
Lethal Temperature ◽  
Hordeum Vulgare L ◽  
Wheat Seedlings ◽  
Time Required

Increasing the duration of freezing of Kharkov winter wheat (Triticum aestivum L.) demonstrated that severe injury does not occur to plants at a freezing temperature (−6 C) well above the lethal temperature for at least 5 days, but progressively more damage occurs as the temperature approaches the killing point (−20 C). High levels of cold hardiness can be induced rapidly in Kharkov winter wheat if seedlings are grown for 4–6 days at 15 C day/10 C night, prior to being exposed to hardening conditions including diurnal freezing to −2 C. The cold hardiness of Kharkov and Rideau winter wheat seedlings grown from 1-yr-old seed was greater than that from 5-yr-old seed. Cold-acclimated Kharkov winter wheat and Dover winter barley (Hordeum vulgare L.) demonstrated the capacity to reharden after varying periods under dehardening conditions. The time required to reharden and the maximum level of hardiness attained by the plants was dependent on the amount of dehardening. Considerable rehardening was observed even when both dehardening and rehardening were carried out in the dark.

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.

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