Intermittent freezing mode to reduce frost heave in freezing soils — experiments and mechanism analysis

2012 ◽  
Vol 49 (6) ◽  
pp. 686-693 ◽  
Author(s):  
Yang Zhou ◽  
Guoqing Zhou
Keyword(s):  
Growth Process ◽  
Frost Heave ◽  
Silty Clay ◽  
Mechanism Analysis ◽  
Test Results ◽  
Practical Application ◽  
Freezing Front ◽  
Freezing Test ◽  
Initial Freezing ◽  
Step Type

Two types of freezing tests have been conducted on Xuzhou silty clay. The intermittent freezing test results show that the frost heave increases step by step after the initial freezing stage, and its total amount is only 48.8% that resulting from the continuous freezing test. A model describing the growth process of the active ice lens in saturated, rigid soils has been established, and the importance of the frozen fringe is investigated in the model. The growth processes of the final ice lenses in the two freezing tests have been used for laboratory validation of the model, and the calculated results are in general agreement with the experimental data. The mechanism of using an intermittent freezing mode to reduce frost heave has been revealed by analyzing the growth process of the final ice lens. We indicate that, during the noncooling stage, the backward movement of the freezing front, which causes the disappearance of the frozen fringe, stops the growth of the final ice lens. This effect results in a step-type frost heave curve in the intermittent freezing test and reduces the heave amount effectively. Finally, problems concerning the practical application of the intermittent freezing mode are discussed in a preliminary manner.

Frost Heave and Water Uptake Relations in Variably Saturated Aggregate Base Materials

2003 ◽  
Vol 1821 (1) ◽  
pp. 13-19 ◽  
Author(s):  
W. Spencer Guthrie ◽  
åke Hermansson
Keyword(s):  
Base Material ◽  
Primary Source ◽  
Frost Heave ◽  
Soil Conditions ◽  
Freezing Process ◽  
Freezing Front ◽  
Base Materials ◽  
Additional Water ◽  
Initial Freezing ◽  
Aggregate Base

The occurrence of frost heave in soils and aggregates can be attributed to the redistribution of water in the soil profile. Frost heave testing performed in this study on 71 variably saturated specimens of aggregate base material indicates that although the uptake of new water from outside the soil body is a primary source of moisture in the formation of segregation ice, internal water residing within the soil or aggregate structure can serve as an important supply of water to the freezing front. Frost heave concepts relating to unsaturated soil conditions were reviewed, and a laboratory methodology was employed to study the relationships between the physical properties of the specimens and their frost heave behavior. Degrees of saturation ranging from 45% to 84% were evaluated, and heave–uptake ratios as high as 2.24 were calculated. Ratios less than 1.09 suggest that sufficient porosity exists in the sample matrix to allow the formation of ice without causing frost heave; higher ratios designate samples that are nearly saturated and that undergo substantial upward redistributions of existing water during the initial freezing process, which gives rise to measurable heave even before additional water is imbibed by the sample. The entry of air into freezing soils and aggregates can play an important role in their frost heave behavior.

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.

Water–heat migration and frost-heave behavior of a saturated silty clay with a water supply

2017 ◽  
Vol 30 (6) ◽  
pp. 517-529 ◽  
Author(s):  
Mingyi Zhang ◽  
Xiyin Zhang ◽  
Xiangtian Xu ◽  
Jianguo Lu ◽  
Wansheng Pei ◽  
...  
Keyword(s):  
Water Supply ◽  
Frost Heave ◽  
Silty Clay

Analysis of Fatigue Mechanical Behaviors of Welding Conformations in Orthotropic Steel Bridge Deck

2015 ◽  
Vol 1096 ◽  
pp. 562-566 ◽  
Author(s):  
Bo Yu ◽  
Tao Hong ◽  
Jian Zhang ◽  
Qing Yu Liang
Keyword(s):  
Fatigue Damage ◽  
Bridge Deck ◽  
Fatigue Tests ◽  
Steel Bridge ◽  
Test Results ◽  
Practical Application ◽  
Mechanical Behaviors ◽  
Homogeneous Test ◽  
Orthotropic Steel Bridge Deck ◽  
Damage Theory

Due to the superior structure style, orthotropic steel bridge deck has been getting more and more widely practical application. The static and fatigue tests of the orthotropic steel bridge deck models were carried out in this research paper, which presented the fatigue damage developing laws, compared the test results with homogeneous test results in existing documents, and according to the relative fatigue accumulative damage theory, the fatigue accumulative damage equations of the sectional specimen and the whole specimen are respectively studied.

scholarly journals THE MAIN TEST RESULTS OF THE MI-2MSB HELICOPTER EQUIPPED WITH THE EXPERIMENTAL SYSTEM OF SMALL ARMS AND SERIES-PRODUCED SYSTEM OF UNGUIDED MISSILE ARMAMENT

2020 ◽  
pp. 26-32
Author(s):  
A. Berezniak ◽  
Т. Dudnik ◽  
O. Zakutko
Keyword(s):  
Experimental System ◽  
Operating Conditions ◽  
Test Results ◽  
Practical Application ◽  
Flight Crew ◽  
Small Arms ◽  
Functional Capabilities ◽  
Actual Volume ◽  
Type C ◽  
Missile System

The summarized results of special tests of the Mi-2MSB helicopter equipped with the experimental system of 12,7 mm small arms (as a part with series-produced machine guns NSVT-12,7) and the serial system of unguided missile armament (NAR type C-8) are presented. The actual volume of assessments of inspections and work performed during the tests is given. According to the results of processing the test materials, it was determined that the tactical range of the Mi-2MSB helicopter with the installed weapons system and boxes for collecting spent units (in the design provided for testing) at a takeoff mass of 3700 kg, at an altitude of not more than 300 m during combat mission in the area of the target for 5 minutes and the remaining fuel on the landing of 100 liters is (not less): version of combat equipment 2 × B8V8MSB (payload - 16 NAR) - 190 km; version of combat equipment 2 × NSVT-12.7 (payload - 600 rounds) - 200 km; version of combat equipment 2 × B8V8MSB + 2 × NSVT-12.7 (payload - 16 NAR and 600 rounds) - 155 The results of special tests practically showed that the Mi-2MSB helicopter, equipped with an aviation weapon system, in addition to the functional tasks defined for the basic Mi-2MSB helicopter, is able to provide: training and maintenance of skills for flight crew in the practical application of unguided aviation weapons and gun armaments in all types of maneuvering, defined by the tactics of army aviation; accomplishment of certain tasks on air support of columns of troops on the march and fire missions on destruction of enemy manpower, single unarmored and lightly armored targets such as car, armored personnel carrier, infantry fighting vehicle, boat, The main combat and functional capabilities in the actual operating conditions confirmed by the results of special tests as well as their validation of specified requirements make it possible (after eliminating the shortcomings identified in the test), to allow operation of Mi-2MSB helicopter in the entire operating range of heights and speeds equipped with aircraft weapons as part of the unguided missile system (NAR type C-8) and small arms system (as part of the series-produced machine guns NSVT-12.7)).

A System of Selective Non Catalytic Reduction of NOx for Diesel Engine

2011 ◽  
Vol 201-203 ◽  
pp. 643-646 ◽  
Author(s):  
Bo Yan Xu ◽  
Hai Ying Tian ◽  
Jie Yang ◽  
De Zhi Sun ◽  
Shao Li Cai
Keyword(s):  
Catalytic Reduction ◽  
Three Dimensional ◽  
Exhaust Gas ◽  
Test Results ◽  
Practical Application ◽  
Three Dimensional Model ◽  
Reduction Efficiency ◽  
Different Temperatures ◽  
Reduction Of Nox ◽  
Good Agreement

SNCR (Selective Non Catalytic Reduction) system is proposed, with 40% methylamine aqueous solution as reducing agent to reduce NOx in diesel exhaust gas. The effect of injection position and volume on the reduction efficiency through the test bench is systematically researched. A three-dimensional model of a full-sized diesel SNCR system generated by CFD software FIRE is used to investigate the reduction efficiency under different temperatures. The simulated results have a good agreement with the test results, and it can be used to optimize SNCR system. The results can indicate the practical application of this technology.

Effect of Temperature Gradients on the Frost Heave of a Saturated Silty Clay with a Water Supply

2017 ◽  
Vol 31 (4) ◽  
pp. 04017011 ◽  
Author(s):  
Mingyi Zhang ◽  
Xiyin Zhang ◽  
Shuangyang Li ◽  
Jianguo Lu ◽  
Wansheng Pei
Keyword(s):  
Water Supply ◽  
Temperature Gradients ◽  
Frost Heave ◽  
Effect Of Temperature ◽  
Silty Clay

Development of a snow-fraction meter based on the conductometric method

1993 ◽  
Vol 18 ◽  
pp. 60-64 ◽  
Author(s):  
Takuo Kitahara ◽  
Masataka Shirakashi ◽  
Yasuhiro Kajio
Keyword(s):  
New Technology ◽  
New Method ◽  
Pipeline System ◽  
Water Mixture ◽  
Test Results ◽  
Practical Application ◽  
Conductometric Method ◽  
Snow Properties ◽  
Snow Water

Hydraulic conveying of snow is one of the most promising techniques for snow removal from an urban area. The method for measuring the fraction of snow in a snow-water mixture flowing in a pipe is a key technique for its practical application. A new method based on the conductometric method has been developed in this study. The method was tested using a prototype snow-fraction meter in a testing apparatus and a closed pipeline system. This type of meter has the advantage of in situ measurement of a wide fraction range from zero up to packed value. The meter is capable of quick response, independent of flow velocity or snow properties and nonintrustive in flow. This paper describes the application of techniques for the development of the meter and the test results. This new method is expected to be useful for hydraulic conveying of ice particles or ice cubes, a new technology in the air-conditioning field.

A Simple Mechanism Solution for Predicting the Collapse Loads of I-Beams Subjected to Concentrated Load

2006 ◽  
Vol 306-308 ◽  
pp. 703-708
Author(s):  
Yi Fu ◽  
Xin Hua Ji ◽  
Jin Long Chen ◽  
Yu Wen Qin
Keyword(s):  
Finite Element ◽  
Design Method ◽  
Close Correlation ◽  
Mechanism Analysis ◽  
Practical Application ◽  
Concentrated Load ◽  
Plastic Mechanism ◽  
Web Buckling ◽  
Hot Rolled ◽  
Theoretical Results

In order to solve the problem of web buckling for hot rolled I-beams without membrane subjected to concentrated load, a plastic mechanism analysis that involves consideration of the plastic hinges developing in the flanges and the yield lines forming in the web plate have been made, and a simple theoretical prediction of collapse loads have been developed. At the same time, wide ranges of finite element studies have been made. Based on the finite element results, certain approximations and empirical modifications are introduced because of the complex geometrical nature of the problem and the purpose to make the resulting design method simple enough for routine practical application. The theoretical results have been compared, and show close correlation, with the finite element results.

Water flow induced by soil freezing

1977 ◽  
Vol 14 (2) ◽  
pp. 237-245 ◽  
Author(s):  
Wayne D. Arvidson ◽  
Norbert R. Morgenstern
Keyword(s):  
Freezing Temperature ◽  
Soil Freezing ◽  
Frost Heave ◽  
Freezing Front ◽  
Overburden Pressure ◽  
Soil Frost ◽  
Freezing Soil ◽  
Volumetric Expansion ◽  
Pressure Water

A study to observe the effects of overburden pressure and other parameters on the freezing behavior of a saturated soil was undertaken. A linear relationship between effective overburden pressure and the flow of water into or out of a freezing soil was observed. The effective pressure at which no flow occurred was termed the shutoff pressure. At pressures less than the shutoff pressure water was sucked to the freezing front resulting in segregated ice, ice lensing, and heaving. This heaving could significantly exceed the heave due to the volumetric expansion of the in situ porewater. At pressures greater than the shutoff pressure water was expelled from the freezing front thereby reducing the volume of in situ water and resulting in a relatively small amount of heave. Shutoff pressure was observed to depend on soil type, stress history, and freezing temperature. The effects of overburden pressure upon flow of water in a freezing soil and frost heave were recommended as additional criteria for assessing soil frost susceptibility.

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