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.

scholarly journals Experimental Study on Freeze-Thaw Cycle Duration of Saturated Tuff

2020 ◽  
Vol 2020 ◽  
pp. 1-10
Author(s):  
Man Huang ◽  
Bin Tang ◽  
Jianliang Jiang ◽  
Renqiu Guan ◽  
Huajun Wang
Keyword(s):  
Phase Transition ◽  
Power Function ◽  
Melting Process ◽  
Freezing Process ◽  
Freeze Thaw ◽  
Thaw Cycle ◽  
Freeze Thaw Cycle ◽  
Initial Melting ◽  
Time Required ◽  
Ice Water

The freeze-thaw duration is one of the important factors affecting the change of rock properties. However, this factor has not formed a unified standard in the freeze-thaw cycle test. This study uses saturated tuff samples taken from eastern Zhejiang, China, as research objects to explore the change law of the time required for the rock to reach a full freeze-thaw cycle. Measured results show that the total duration of the freeze-thaw cycle presents an increasing power function with the increase in the number of freeze-thaw cycles. The freezing process is divided into three phases: initial freezing, water-ice phase transition, and deep freezing. The melting process is also divided into three phases: initial melting, ice-water phase transition, and deep melting. The time required for the ice-water phase change stage of the melting process does not change with the increase in the number of freeze-thaw cycles, while the other stages increase as a power function. The proportion of duration of each stage in the freezing process does not change with the increase in the number of cycles. By contrast, the duration proportion of the initial melting phase in the melting process decreases, and the deep melting phase increases. Experimental results of the freeze-thaw cycles of tuff demonstrate that the freeze-thaw duration of the freeze-thaw cycles within 40 times can be set to 9 h. The freezing and melting processes are 6 and 3 h, respectively.

Study on Influence of Freeze-Thaw Cycles on the Physical-Mechanical Properties of Loess

2012 ◽  
Vol 442 ◽  
pp. 286-290
Author(s):  
Gui Quan Bi
Keyword(s):  
Mechanical Properties ◽  
Water Content ◽  
Water Distribution ◽  
Early Stage ◽  
Frozen Soil ◽  
Dry Density ◽  
Freeze Thaw ◽  
Thaw Cycle ◽  
Freeze Thaw Cycle ◽  
Filling Water

Loess foundations in seasonally frozen soil region are subject to severe effect of freeze-thaw cycles. This often results in water redistribution and structure weakening. So it is very important to study the physical-mechanical properties of loess under freeze-thaw cycles. In this paper, systematic study was carried out using freeze-thaw cycle machine. The impacts of freeze-thaw cycles on the physical-mechanical properties of loess including deformation, water distribution and dry density under the condition of filling water to loess samples were investigated. The results proved that the freeze-thaw cycles can increase the water content gradually from the bottom to the top in the loess samples under water supplied condition. The water content gradient reaches maximum at the freeze-thaw interface. The loess samples deform sharply at the early stage of the freeze-thaw cycles and then reach a stable status. The freeze-thaw cycles decrease the dry density of the loess samples gradually. The dry density at the top is lower than that at the bottom, due to more severe freeze-thaw effect at the top of the samples.

Modeling soil freeze-thaw and ice effect on canal bank

1998 ◽  
Vol 35 (4) ◽  
pp. 655-665 ◽  
Author(s):  
Z X Zhang ◽  
R L Kushwaha
Keyword(s):  
Frozen Soil ◽  
Soil Freezing ◽  
Frost Heave ◽  
Energy Status ◽  
Abrupt Increase ◽  
Water Ice ◽  
Freeze Thaw ◽  
Thaw Cycle ◽  
Initial Soil ◽  
Freeze Thaw Cycle

The experiments for modeling soil freeze-thaw and ice action on canal banks were conducted in a laboratory. In addition to the frost heave that was observed during the period of soil freezing, there was an abrupt increase in frost heave that occurred at the beginning of soil thawing. This phenomenon lasted for over approximately 100 hours, and the frost heave induced during this period reached as much as 22.62 mm. At the same time, peak ice pressures also occurred as the soil was thawing. It has been suggested that the frost heave during initial soil thawing may be associated with the change in energy status at the water-ice interface resulting from the buildup of internal stress in the soil during the formation of ice lenses.Key words: frozen soil, freeze-thaw cycle, frost heave, thawing settlement, canal protection.

Stress–Strain Assessments for Buried Oil Pipelines Under Freeze-Thaw Cyclic Conditions

2021 ◽  
Vol 143 (4) ◽  
Author(s):  
Zhen-Chao Teng ◽  
Xiao-Yan Liu ◽  
Yu Liu ◽  
Yu-Xiang Zhao ◽  
Kai-Qi Liu ◽  
...  
Keyword(s):  
Frozen Soil ◽  
Ratchet Effect ◽  
Frost Heaving ◽  
Soil Frost ◽  
Oil Pipeline ◽  
Freeze Thaw ◽  
Thaw Cycle ◽  
Oil Pipelines ◽  
Freeze Thaw Cycle ◽  
Effect Theory

Abstract In this study, outdoor freeze-thaw cyclic tests on the Q345 steel pipeline portion were conducted to analyze the buried oil pipeline stress evolution in a seasonally frozen soil area, namely, the Mohe–Daqing portion of China–Russia crude oil pipeline. The results obtained show that under the freeze-thaw cycle, the variation trend of soil temperature around the pipeline exhibited a hysteresis pattern, which was similar to that of atmospheric temperatures. The soil frost heaving force was shown to drop with depth, and its value at the pipe top was higher than that at the pipe bottom. With the number of freeze-thaw cycles, the frost heaving force of the soil first increased and finally stabilized, while the principal stress of the pipeline increased gradually, and its extreme value tended to be stable after 7–8 cycles, which was consistent with the “ratchet effect” theory. The above findings made it possible to elaborate on a more efficient freeze-thaw cyclic test setup for clarifying the mechanism of frozen soil/pipeline interactions.

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

Tests and Research on Characteristics of Shear Strength of Cement Improved Soil under Freeze-Thaw Cycle

2014 ◽  
Vol 1015 ◽  
pp. 105-109 ◽  
Author(s):  
An Ping Zhao ◽  
Ai Ping Tang ◽  
Jing Sun ◽  
Xue Mei Yu
Keyword(s):  
Shear Strength ◽  
Traffic Safety ◽  
Frost Damage ◽  
Frozen Soil ◽  
Strong Impact ◽  
Silty Clay ◽  
Freeze Thaw ◽  
Thaw Cycle ◽  
Freeze Thaw Cycle ◽  
Cement Soil

Roadbed filling undergo at least one freeze-thaw cycle every year in seasonal frozen soil areas, which will lead subgrade to boiling, settlement, strength weakening etc. and has a strong impact on traffic safety and smooth, need to be solved urgently . In recent years, cement improved soil is applied to dissolve frost damage because it can be obtained locally, and has high performance and low price. However, how to evaluate strength of cement soil under repeated freeze-thaw cycles is the key to its further application in those regions. In the paper, the cement improved silty clay is selected as the object which is most common in Heilongjiang roadbed, many groups of freeze-thaw tests and direct shear tests are conducted at different conditions. From these tests, some conclusions about shear strength index and are obtained: 1. the first freeze-thaw cycle has important effect on cohesion of cement soil, during freeze-thaw cycle, the lower temperature is, the faster is decreasing. 2. decreases with freeze-thaw cycles increase, and there is a peak value existing after the seventh cycle, then reduce rapidly. 3. the internal friction angle appears decreasing – increasing–reducing– increasing trend during cycles but the range of change is little. 4. reduces smaller and increases more when temperature is lower.

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.

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