EXPERIMENTAL AND THEORETICAL STUDY ON FREEZE-THAWING DAMAGE PROPAGATION OF SATURATED ROCKS

2008 ◽  
Vol 22 (09n11) ◽  
pp. 1853-1858 ◽  
Author(s):  
QUANSHENG LIU ◽  
GUANGMIAO XU ◽  
XIAOYAN LIU
Keyword(s):  
Uniaxial Compression ◽  
Influence Factors ◽  
Compression Tests ◽  
Freezing And Thawing ◽  
Uniaxial Compression Strength ◽  
Red Sandstone ◽  
Damage Propagation ◽  
Freeze Thaw ◽  
Thaw Cycle ◽  
Damage Process

The freezing and thawing cycles tests were conducted on red sandstone and shale. In this paper, freezing-thawing damage propagation processes are analyzed, and two deterioration modes, i.e. scaling mode for red sandstone and fracturing mode for shale, are suggested. The uniaxial compression tests are also conducted on the two types of rock subjected to different freeze-thaw cycles at room temperature. It is shown that the uniaxial compression strength and the elastic modulus of rocks at low-temperature depended on the number of freeze-thaw cycles. The mechanism and influence factors of rock deterioration due to freeze-thaw are analyzed, and the damage process of rock should be divided into two coupled parts: rocks damage due to freeze-thaw cycle as well as the damage propagation caused by stress erosion. The damage evolvement equations for the two rocks are established, and the constitutive equations for the two types of rock subjected to freeze-thaw are deduced, accordingly. It is approved that the constitutive model considering the freeze-thaw damage is credible and can be used for the following theory analysis.

scholarly journals Mechanical Properties of Sandstone Cement-Stabilized Macadam

2019 ◽  
Vol 9 (17) ◽  
pp. 3460 ◽  
Author(s):  
Qiang Du ◽  
Ting Pan ◽  
Jing Lv ◽  
Jie Zhou ◽  
Qingwei Ma ◽  
...  
Keyword(s):  
Cement Content ◽  
Influence Factors ◽  
Road Construction ◽  
Experimental Investigations ◽  
Freezing And Thawing ◽  
Freeze Thaw ◽  
Test Pieces ◽  
Thaw Cycle ◽  
Freeze Thaw Cycle ◽  
Brazilian Splitting

Application of sandstone in cement-stabilized macadam (CSM) is an effective way to utilize sandstone. To determine the feasibility of using sandstone as a CSM aggregate, a series of experimental investigations, such as unconfined compressive strength (UCS) tests, Brazilian splitting tests and freeze-thaw cycle tests, were conducted on sandstone cement-stabilized macadam (SCSM). Three mixed variables, covering the cement content, aggregate type and curing period, were set as influence factors. The testing results indicated that the UCS, indirect tensile strength (ITS) and frost resistance property of the test-pieces increased with cement content and curing age. Considering the asphalt pavement design specifications for China, the UCS and ITS values of the SCSM complied with the requirements of light traffic road construction before freeze-thaw cycles. However, the SCSM subjected to freezing and thawing meets the requirements only when the cement content is 4.5%. Therefore, it is noteworthy that CSM containing sandstone aggregates should be applied with caution in cold region because of insufficient freeze resistance.

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.

scholarly journals USING SMOS PASSIVE MICROWAVE DATA TO DEVELOP SMAP FREEZE/THAW ALGORITHMS ADAPTED FOR THE CANADIAN SUBARCTIC

2015 ◽  
Vol XL-1-W5 ◽  
pp. 365-368 ◽  
Author(s):  
P. Kalantari ◽  
M. Bernier ◽  
K. C. McDonal ◽  
J. Poulin
Keyword(s):  
Land Cover ◽  
Time Series Data ◽  
Passive Microwave ◽  
Soil Freezing ◽  
Series Data ◽  
Freezing And Thawing ◽  
Freeze Thaw ◽  
Thaw Cycle ◽  
Freeze Thaw Cycle ◽  
The Impact

Seasonal terrestrial Freeze/Thaw cycle in Northern Quebec Tundra (Nunavik) was determined and evaluated with passive microwave observations. SMOS time series data were analyzed to examine seasonal variations of soil freezing, and to assess the impact of land cover on the Freeze/Thaw cycle. Furthermore, the soil freezing maps derived from SMOS observations were compared to field survey data in the region near Umiujaq. The objective is to develop algorithms to follow the seasonal cycle of freezing and thawing of the soil adapted to Canadian subarctic, a territory with a high complexity of land cover (vegetation, soil, and water bodies). Field data shows that soil freezing and thawing dates vary much spatially at the local scale in the Boreal Forest and the Tundra. The results showed a satisfactory pixel by pixel mapping for the daily soil state monitoring with a > 80% success rate with in situ data for the HH and VV polarizations, and for different land cover. The average accuracies are 80% and 84% for the soil freeze period, and soil thaw period respectively. The comparison is limited because of the small number of validation pixels.

scholarly journals Study on Relaxation Damage Properties of High Viscosity Asphalt Sand under Uniaxial Compression

2018 ◽  
Vol 2018 ◽  
pp. 1-12 ◽  
Author(s):  
Yazhen Sun ◽  
Zhangyi Gu ◽  
Jinchang Wang ◽  
Chenze Fang ◽  
Xuezhong Yuan
Keyword(s):  
Uniaxial Compression ◽  
Viscoelastic Model ◽  
Relaxation Modulus ◽  
Maxwell Model ◽  
High Viscosity ◽  
Secondary Development ◽  
Compression Tests ◽  
Crack Control ◽  
Different Temperatures ◽  
Damage Process

Laboratory investigations of relaxation damage properties of high viscosity asphalt sand (HVAS) by uniaxial compression tests and modified generalized Maxwell model (GMM) to simulate viscoelastic characteristics coupling damage were carried out. A series of uniaxial compression relaxation tests were performed on HVAS specimens at different temperatures, loading rates, and constant levels of input strain. The results of the tests show that the peak point of relaxation modulus is highly influenced by the loading rate in the first half of an L-shaped curve, while the relaxation modulus is almost constant in the second half of the curve. It is suggested that for the HVAS relaxation tests, the temperature should be no less than −15°C. The GMM is used to determine the viscoelastic responses, the Weibull distribution function is used to characterize the damage of the HVAS and its evolution, and the modified GMM is a coupling of the two models. In this paper, the modified GMM is implemented through a secondary development with the USDFLD subroutine to analyze the relaxation damage process and improve the linear viscoelastic model in ABAQUS. Results show that the numerical method of coupling damage provides a better approximation of the test curve over almost the whole range. The results also show that the USDFLD subroutine can effectively predict the relaxation damage process of HVAS and can provide a theoretical support for crack control of asphalt pavements.

scholarly journals The Effect of Bedding Structure on Mechanical Property of Coal

2014 ◽  
Vol 2014 ◽  
pp. 1-7 ◽  
Author(s):  
Zetian Zhang ◽  
Ru Zhang ◽  
Guo Li ◽  
Hegui Li ◽  
Jianfeng Liu
Keyword(s):  
Mechanical Property ◽  
Uniaxial Compression ◽  
Peak Stress ◽  
Natural Fracture ◽  
Test Results ◽  
Compression Tests ◽  
Average Amount ◽  
Uniaxial Compression Strength ◽  
Bedding Planes ◽  
Close Relationship

The mechanical property of coal, influencing mining activity considerably, is significantly determined by the natural fracture distributed within coal mass. In order to study the effecting mechanism of bedding structure on mechanical property of coal, a series of uniaxial compression tests and mesoscopic tests have been conducted. The experimental results show that the distribution characteristic of calcite particles, which significantly influences the growth of cracks and the macroscopic mechanical properties of coal, is obviously affected by the bedding structure. Specifically, the uniaxial compression strength of coal sample is mainly controlled by bedding structure, and the average peak stress of specimens with axes perpendicular to the bedding planes is 20.00 MPa, which is 2.88 times the average amount of parallel ones. The test results also show a close relationship between the bedding structure and the whole deformation process under uniaxial loading.

Two-Parameter Parabolic Mohr Strength Criterion and Its Damage Regularity

2006 ◽  
Vol 306-308 ◽  
pp. 327-332 ◽  
Author(s):  
Chun Guang Li ◽  
Xiu Run Ge ◽  
Hong Zheng ◽  
Shui Lin Wang
Keyword(s):  
Uniaxial Tension ◽  
Principal Stress ◽  
Uniaxial Compression ◽  
Strength Criterion ◽  
Friction Angle ◽  
Tensile Failure ◽  
Compression Tests ◽  
Uniaxial Compression Strength ◽  
Griffith Criterion ◽  
Two Parameter

A series of formulas about two-parameter parabolic Mohr strength criterion(2-PP Mohr criterion) are derived. Based on the results of uniaxial tension and uniaxial compression tests, the parameters involved in the criterion can be easily determined, then the criterion in terms of the major principal stress and the minor principal stress is derived, and the damage pattern is also discussed. At last, the formulas about the rupture angle and the friction angle are presented, and their relationship is also given. 2-PP Mohr criterion can describe not only shear but also tensile failure. In this criterion the ratio of the uniaxial compression strength and the uniaxial tension strength is not confined as in Griffith criterion. The formula about the rupture angle provides steady theoretical foundation for determining the direction of crack faces and damage patterns in the computation of macro crack propagation. In fact, Griffith criterion is only a special case of the two-parameter parabolic Mohr strength criterion proposed in this present paper.

Etude de la résistance au gel de bétons contenant un fluidifiant

1991 ◽  
Vol 18 (4) ◽  
pp. 581-589 ◽  
Author(s):  
Michel Pigeon ◽  
Marcel Langlois
Keyword(s):  
Silica Fume ◽  
Plain Concrete ◽  
Freezing And Thawing ◽  
Freezing Resistance ◽  
Cement Ratio ◽  
Water Cement Ratio ◽  
Freeze Thaw ◽  
Spacing Factor ◽  
Thaw Cycle ◽  
Air Void

There is some controversy about freezing resistance of concrete containing superplasticizers. It has been quite convincingly demonstrated that, in some cases, such admixtures can significantly alter air-void systems in concrete. Some researchers believe, however, that concrete with superplasticizers can resist frost even when the air-void spacing factor is higher than the usual limit of 200 μm. The freeze–thaw cycle resistance tests described in this paper show that with the two types of concrete tested (a plain concrete with a water/cement ratio of 0.50 and a concrete with the same water/cement ratio but containing silica fume), the critical air-void spacing factor value is not significantly affected by the presence of a superplasticizer. When regular concrete is to be exposed to freeze–thaw conditions, the air-void system should meet the usual standards even when a superplasticizer is present. Key words: concrete, freezing and thawing, durability, superplasticizer, spacing factor, silica fume, water–cement ratio. [Journal translation]

scholarly journals PSXIII-2 Cryopreservation effect on biological parameters of poultry semen

2019 ◽  
Vol 97 (Supplement_3) ◽  
pp. 372-373
Author(s):  
Mikhail A Zhilinsky ◽  
Evgeniya K Tomgorova ◽  
Baylar S Iolchiev ◽  
Anastasia N Vetokh ◽  
Hanum V Ashraf ◽  
...  
Keyword(s):  
Germ Cells ◽  
Genetic Material ◽  
Middle Section ◽  
Sperm Cryopreservation ◽  
Freezing And Thawing ◽  
Freeze Thaw ◽  
Thaw Cycle ◽  
Freeze Thaw Cycle ◽  
Negative Effect ◽  
Live Sperm

Abstract Sperm cryopreservation is one of the most important elements for the creation of genetic material cryobanks in order to preserve the gene pool of poultry. Cryopreservation methods and parameters directly affect the viability of germ cells after thawing. The effect of freeze-thaw cycles on biological usefulness of bird sperm was studied. Semen was frozen in paillettes. Thawing sperm was carried out at a temperature of 38 °С. Sperm activity was assessed using CASA technology “ARGUSSOFT”. Sperm motility after cryopreservation decreased in roosters, quails and guinea fowls by 62 ± 3 %, 66 ± 1 % and 60 ± 1 %, respectively. The proportion of live sperm also decreased: in roosters - from 89 ± 4 % to 48 ± 2 %, in quails - from 93 ± 3 % to 49 ± 3 %, in the guinea fowls - from 92 ± 2 % to 45 ± 4 %. As a result of freezing and thawing, the proportion of spermatozoa with abnormal morphology increased. A change in the frequency of anomalies occurrence in individual segments was observed. The number of spermatozoa with flagella pathology was increased. The proportion of sperm with pathology of the head, middle section and flagellum increased by 0.4 %, 0.4 % and 1.3 % (P ≤ 0.001) respectively, in the frozen-thawed samples of roosters, compared with the indicators established for a freshly obtained ejaculate. A similar trend was observed in other poultry types. Thus, the freeze-thaw cycle had a negative effect on the activity and viability of poultry spermatozoa. Supported by RSF No 16-16-04104.

Laboratory Test of Uniaxial Compressive Strength of Shanghai Frozen Soils under Freeze-Thaw Cycle

2013 ◽  
Vol 716 ◽  
pp. 688-692 ◽  
Author(s):  
Xiang Dong Hu ◽  
Jin Tai Wang ◽  
Xing Fu Yu
Keyword(s):  
Soft Soil ◽  
Underground Space ◽  
Freezing And Thawing ◽  
Frozen Soils ◽  
Freeze Thaw ◽  
Thaw Cycle ◽  
Ground Freezing ◽  
Freeze Thaw Cycle ◽  
Artificial Ground Freezing ◽  
Mechanical Characters

The artificial ground freezing (AGF) is now widely employed in constructions with the expanding underground space exploitation in Shanghai. In order to avoid geological disasters which might appear in the AGF practice, it is urgently needed to do laboratory tests on the physical and mechanical characters of Shanghai soft soil under freezing and thawing action. This paper tests three kinds of soils from the location ofShanghai Metro line 4 constructions in different state, i.e. original state, freeze-thaw state and secondary freeze-thaw state, and obtains the changing rules of soil characters under secondary freeze-thaw action.

scholarly journals Numerical Simulation of the Effect of Freeze–Thaw Cycles on the Durability of Concrete in a Salt Frost Environment

Coatings ◽  
2021 ◽  
Vol 11 (10) ◽  
pp. 1198
Author(s):  
Hao Li ◽  
Yuan Zhang ◽  
Haolong Guo
Keyword(s):  
Numerical Simulation ◽  
Bending Moment ◽  
Temperature Curve ◽  
Concrete Durability ◽  
Freezing And Thawing ◽  
Freeze Thaw ◽  
Thaw Cycle ◽  
Freeze Thaw Cycle ◽  
The Impact ◽  
Erosion Environment

In order to improve the accuracy of the analysis of the impact of freeze–thaw cycle on concrete durability in a salt freezing environment, the numerical simulation of the impact of the freeze–thaw cycle on concrete durability in a salt freezing erosion environment is studied in this paper. Firstly, considering the influence of axial force and bending moment on the relationship between bending moment and curvature, a concrete fiber beam column model is established. Then, according to the joint influence of temperature field, stress field and seepage field on concrete in the process of freezing and thawing, the control differential equation of the freezing and thawing cycle is established. The freeze–thaw damage section is divided, the non-uniform distribution of freeze–thaw damage is determined, and the division of the freeze–thaw damage section is completed. According to the linear relationship between freeze–thaw damage degree, relative dynamic elastic modulus, freeze–thaw cycle times and position variables, the durability of concrete is numerically simulated, and the attenuation law of bond strength at different section depths after freeze–thaw is determined. The results show that the temperature curve simulated by the design method is consistent with the actually measured temperature curve, which can better reduce the temperature change of the inner core of the test block during freezing and thawing, and the relative dynamic elastic modulus is in good agreement with the actual value, which can prove that the method in this paper has certain practical application value. It is expected to provide some reference for solving the durability problem of concrete in a salt frost erosion environment and the optimal design of concrete structures.

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