scholarly journals Estimation of Ice Content in Mortar Based on Electrical Measurements under Freeze-Thaw Cycle

2016 ◽  
Vol 14 (2) ◽  
pp. 35-46 ◽  
Author(s):  
Yi Wang ◽  
Fuyuan Gong ◽  
Dawei Zhang ◽  
Tamon Ueda
Keyword(s):  
Electrical Measurements ◽  
Freeze Thaw ◽  
Thaw Cycle ◽  
Freeze Thaw Cycle ◽  
Ice Content

scholarly journals A Freezing-Thawing Damage Characterization Method for Highway Subgrade in Seasonally Frozen Regions Based on Thermal-Hydraulic-Mechanical Coupling Model

Sensors ◽  
2021 ◽  
Vol 21 (18) ◽  
pp. 6251
Author(s):  
Qingsong Deng ◽  
Xiao Liu ◽  
Chao Zeng ◽  
Xianzhi He ◽  
Fengguang Chen ◽  
...  
Keyword(s):  
Rapid Development ◽  
Coupling Model ◽  
Frozen Soil ◽  
Mechanical Coupling ◽  
Damage Area ◽  
Freeze Thaw ◽  
Thaw Cycle ◽  
Freeze Thaw Cycle ◽  
Ice Content ◽  
Ice Water

Seasonally frozen soil where uneven freeze–thaw damage is a major cause of highway deterioration has attracted increased attention in China with the rapid development of infrastructure projects. Based on Darcy’s law of unsaturated soil seepage and heat conduction, the thermal–hydraulic–mechanical (THM) coupling model is established considering a variety of effects (i.e., ice–water phase transition, convective heat transfer, and ice blocking effect), and then the numerical solution of thermal–hydraulic fields of subgrade can be obtained. Then, a new concept, namely degree of freeze–thaw damage, is proposed by using the standard deviation of the ice content of subgrade during the annual freeze–thaw cycle. To analyze the freeze–thaw characteristics of highway subgrade, the model is applied in the monitored section of the Golmud to Nagqu portion of China National Highway G109. The results show that: (1) The hydrothermal field of subgrade has an obvious sunny–shady slopes effect, and its transverse distribution is not symmetrical; (2) the freeze–thaw damage area of subgrade obviously decreased under the insulation board measure; (3) under the combined anti-frost measures, the maximum frost heave amount of subgrade is significantly reduced. This study will provide references for the design of highway subgrades in seasonally frozen soil areas.

Impacts of Permafrost Mean Annual Ground Temperature and Ice Content on Thermal Regime of Pile Foundation of Qinghai-Tibet Power Transmission Line

2012 ◽  
Vol 610-613 ◽  
pp. 2832-2839 ◽  
Author(s):  
Guo Yu Li ◽  
Qi Hao Yu ◽  
Wei Ma ◽  
Yan Hu Mu
Keyword(s):  
Power Transmission ◽  
Power Transmission Line ◽  
Permafrost Degradation ◽  
Enhanced Heat Transfer ◽  
Freeze Thaw ◽  
Thaw Cycle ◽  
Concrete Pile ◽  
Freeze Thaw Cycle ◽  
Surface Disturbance ◽  
Ice Content

The ±400 kV Qinghai-Tibet Power Transmission Line (QTPTL) was officially operated in December of 2011 on the Qinghai-Tibet Plateau (QTP) in China, crossing 550-km-long permafrost and 438-km-long seasonally frozen ground regions. Some of tower foundations of the QTPTL were buried in permafrost. It faces potential challenges of freeze- and thaw-related geohazards induced by freeze-thaw cycle, active layer thickening and permafrost degradation, which are mainly caused by climate warming, surface disturbance, enhanced heat transfer of concrete pile. These geohazards has become the concerns for stability and integrity of the QTPTL. In this study, some numerical tests on the thermal interaction between pile and permafrost were carried out to investigate impacts of permafrost mean annual ground temperature (MAGT) and ice content of soils surrounding pile on active layer thickening, permafrost degradation and freeze-thaw cycle considering climate warming, surface disturbance and enhanced heat transfer of concrete pile. The research results and discussions are described, which will provide the basis for normal operation and option of countermeasures against thaw settlement and frost jacking of the QTPTL, and the reference for the similar permafrost engineering in cold regions

scholarly journals Effect of freeze–thaw cycle on physical and mechanical properties and damage characteristics of sandstone

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Longxiao Chen ◽  
Kesheng Li ◽  
Guilei Song ◽  
Deng Zhang ◽  
Chuanxiao Liu
Keyword(s):  
Mechanical Properties ◽  
Shear Failure ◽  
Triaxial Compression ◽  
Physical And Mechanical Properties ◽  
Freeze Thaw ◽  
Damage Characteristics ◽  
Large Pore ◽  
Natural Rock ◽  
Thaw Cycle ◽  
Freeze Thaw Cycle

AbstractRock deterioration under freeze–thaw cycles is a concern for in-service tunnel in cold regions. Previous studies focused on the change of rock mechanical properties under unidirectional stress, but the natural rock mass is under three dimensional stresses. This paper investigates influences of the number of freeze–thaw cycle on sandstone under low confining pressure. Twelve sandstone samples were tested subjected to triaxial compression. Additionally, the damage characteristics of sandstone internal microstructure were obtained by using acoustic emission (AE) and mercury intrusion porosimetry. Results indicated that the mechanical properties of sandstone were significantly reduced by freeze–thaw effect. Sandstone’ peak strength and elastic modulus were 7.28–37.96% and 6.38–40.87% less than for the control, respectively. The proportion of super-large pore and large pore in sandstone increased by 19.53–81.19%. We attributed the reduced sandstone’ mechanical properties to the degenerated sandstone microstructure, which, in turn, was associated with increased sandstone macropores. The macroscopic failure pattern of sandstone changed from splitting failure to shear failure with an increasing of freeze–thaw cycles. Moreover, the activity of AE signal increased at each stage, and the cumulative ringing count also showed upward trend with the increase of freeze–thaw number.

Non-linear creep damage model of sandstone under freeze-thaw cycle

2021 ◽  
Vol 28 (3) ◽  
pp. 954-967
Author(s):  
Jie-lin Li ◽  
Long-yin Zhu ◽  
Ke-ping Zhou ◽  
Hui Chen ◽  
Le Gao ◽  
...  
Keyword(s):  
Damage Model ◽  
Creep Damage ◽  
Freeze Thaw ◽  
Thaw Cycle ◽  
Linear Creep ◽  
Non Linear ◽  
Freeze Thaw Cycle ◽  
Creep Damage Model

scholarly journals Strength and Microscopic Damage Mechanism of Yellow Sandstone with Holes under Freezing and Thawing

2020 ◽  
Vol 2020 ◽  
pp. 1-13 ◽  
Author(s):  
Huren Rong ◽  
Jingyu Gu ◽  
Miren Rong ◽  
Hong Liu ◽  
Jiayao Zhang ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Pore Size ◽  
Power Function ◽  
Damage Mechanism ◽  
Uniaxial Compression Test ◽  
Freezing And Thawing ◽  
Freeze Thaw ◽  
Thaw Cycle ◽  
Freeze Thaw Cycle ◽  
Microscopic Damage

In order to study the damage characteristics of the yellow sandstone containing pores under the freeze-thaw cycle, the uniaxial compression test of saturated water-stained yellow sandstones with different freeze-thaw cycles was carried out by rock servo press, the microstructure was qualitatively analyzed by Zeiss 508 stereo microscope, and the microdamage mechanism was quantitatively studied by using specific surface area and pore size analyzer. The mechanism of weakening mechanical properties of single-hole yellow sandstone was expounded from the perspective of microstructure. The results show the following. (1) The number of freeze-thaw cycles and single-pore diameter have significant effects on the strength and elastic modulus of the yellow sandstone; the more the freeze-thaw cycles and the larger the pore size, the lower the strength of the yellow sandstone. (2) The damage modes of the yellow sandstone containing pores under the freeze-thaw cycle are divided into five types, and the yellow sandstone with pores is divided into two areas: the periphery of the hole and the distance from the hole; as the number of freeze-thaw cycles increases, different regions show different microscopic damage patterns. (3) The damage degree of yellow sandstone is different with freeze-thaw cycle and pore size. Freeze-thaw not only affects the mechanical properties of yellow sandstone but also accelerates the damage process of pores. (4) The damage of the yellow sandstone by freeze-thaw is logarithmic function, and the damage of the yellow sandstone is a power function. The damage equation of the yellow sandstone with pores under the freezing and thawing is a log-power function nonlinear change law and presents a good correlation.

Studies the Properties of Polyaspartic Polyurea Coated Concrete under Coaction of Salt Fog and Freeze-Thaw

2012 ◽  
Vol 455-456 ◽  
pp. 781-785
Author(s):  
Ping Lu ◽  
Xin Mao Li ◽  
Xue Qiang Ma ◽  
Wei Bo Huang
Keyword(s):  
Elastic Modulus ◽  
Frost Resistance ◽  
Dynamic Elastic Modulus ◽  
Freeze Thaw ◽  
Decrease Rate ◽  
Thaw Cycle ◽  
Freeze Thaw Cycle ◽  
Salt Fog

. This paper mainly studied the properties of PAE polyurea coated concrete under coactions of salt fog and freeze-thaw. After exposed salt fog conditions for 200d, T3, B2, F2 and TM four coated concrete relative dynamic elastic modulus have small changes, but different coated concrete variation amplitude is different. T3 coated concrete after 100 times of freeze-thaw cycle the relative dynamic elastic modulus began to drop, 200 times freeze-thaw cycle ends, relative dynamic elastic modulus variation is the largest, decrease rate is 95%, TM concrete during 200 times freeze-thaw cycle, relative dynamic elastic modulus almost no change, B2 concrete and F2 concrete the extent of change between coating T3 and TM. After 300 times the freeze-thaw cycle coated concrete didn't appear freeze-thaw damage phenomenon. Four kinds of coating concrete relative dynamic elastic modulus variation by large to small order: T3 coated concrete > B2 coated concrete >F2 coated concrete > TM coated concrete, concrete with the same 200d rule. Frost resistance order, by contrast, TM coated concrete > B2 coated concrete > F2 coated concrete > T3 coated concrete.

Protection of osteoblastic cells from freeze/thaw cycle-induced oxidative stress by green tea polyphenol

2005 ◽  
Vol 27 (9) ◽  
pp. 655-660 ◽  
Author(s):  
Dong-Wook Han ◽  
Hak Hee Kim ◽  
Mi Hee Lee ◽  
Hyun Sook Baek ◽  
Kwon-Yong Lee ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Green Tea ◽  
Osteoblastic Cells ◽  
Tea Polyphenol ◽  
Freeze Thaw ◽  
Thaw Cycle ◽  
Green Tea Polyphenol ◽  
Freeze Thaw Cycle
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