Unloading Creep Characteristics of Frozen Clay Subjected to Long-Term High-Pressure K0 Consolidation before Freezing

Artificial ground freezing has been widely applied in the construction of vertical shafts in deep and thick alluvia. As an important factor, the in situ creep behavior of deep, frozen soil affects the mechanical properties of frozen walls and the safety and stability of shaft linings. Acquiring creep characteristics and deep soil parameters by methods that ignore the engineering and geological situations is currently inadvisable. A series of triaxial unloading tests were conducted with frozen clay subjected to long-term high-pressure K0 consolidation before freezing to research the unloading creep characteristics, creep strength, and other parameters of the clay, and the results indicated the following: (1) The creep behaviors of frozen clay are affected by the consolidation time and consolidation stress. Long-term high-pressure K0 consolidation reduces the creep strain and creep rate of frozen clay. (2) The decrease in the ice and the unfrozen water contents of frozen clay caused by the prolongation of consolidation time result in an increase in the long-term strength and instantaneous strength. Consolidation time has an obvious effect on long-term strength and weakens the creep property of frozen clay. Consolidation stress significantly affects the instantaneous strength. (3) The deformation resistance capability of frozen clay is enhanced by compaction; thus, E1, η1, and η2 increase with prolonged consolidation, and the nonlinearity of the accelerated creep increases.

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Corrigendum to “Unloading Creep Characteristics of Frozen Clay Subjected to Long-Term High-Pressure K0 Consolidation before Freezing”

Advances in Civil Engineering ◽

10.1155/2020/7609163 ◽

2020 ◽

Vol 2020 ◽

pp. 1-1

Author(s):

Jinbo Jia ◽

Yansen Wang ◽

Yangguang Leng

Keyword(s):

High Pressure ◽

Creep Characteristics ◽

Frozen Clay

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Analysis of Creep Characteristics of Shallow Mined-Out Areas Roof under Low Stress Conditions

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.105-107.832 ◽

2011 ◽

Vol 105-107 ◽

pp. 832-836 ◽

Cited By ~ 1

Author(s):

Shu Ren Wang ◽

Hui Hui Jia

Keyword(s):

Creep Deformation ◽

Thick Plate ◽

Plate Theory ◽

Technical Problem ◽

Stress Conditions ◽

Creep Model ◽

Term Strength ◽

Creep Characteristics ◽

Over Time

Under low stress conditions, when the load exerting on the mined-out areas roof is less than the rock long-term strength, the rock roof will generate some creep deformation. In order to prevent the roof of the mined-out areas suddenly collapse, and to ensure the operator and construction equipment above the mined-out areas safety, it is an important security technical problem to reveal the creep characteristics of the shallow mined-out areas roof. Taking the mined-out areas of Antaibao Surface Mine as background, considering the rheological properties of rock roof, and assuming the roof was a rectangular thick plate, the creep characteristics of mined-out areas roof were analysed by applying the thick plate theory and Kelvin creep model. The regression equation of the roof deflection increment over time was given, and the creep characteristics of the shallow mined-out areas roof were revealed also.

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A long-term strength criterion for frozen clay under complex stress states

Cold Regions Science and Technology ◽

10.1016/j.coldregions.2020.103089 ◽

2020 ◽

Vol 176 ◽

pp. 103089

Author(s):

Dun Chen ◽

Wei Ma ◽

Guoyu Li ◽

Zhiwei Zhou ◽

Yanhu Mu

Keyword(s):

Strength Criterion ◽

Complex Stress ◽

Term Strength ◽

Frozen Clay ◽

Stress States

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Long-term strength of nickel-containing alloys in hydrogen at high pressure

Soviet Materials Science ◽

10.1007/bf01159992 ◽

1979 ◽

Vol 14 (6) ◽

pp. 598-601

Author(s):

T. D. Voznyi ◽

Yu. I. Zvezdin ◽

I. A. Povyshev ◽

V. V. Popovich

Keyword(s):

High Pressure ◽

Term Strength

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A Fractional Creep Constitutive Model for Frozen Soil in Consideration of the Strengthening and Weakening Effects

Advances in Materials Science and Engineering ◽

10.1155/2016/5740292 ◽

2016 ◽

Vol 2016 ◽

pp. 1-12 ◽

Cited By ~ 4

Author(s):

Feng Hou ◽

Quanming Li ◽

Enlong Liu ◽

Cheng Zhou ◽

Mengke Liao ◽

...

Keyword(s):

Shear Stress ◽

Constitutive Model ◽

Test Specimen ◽

Confining Pressure ◽

Frozen Soil ◽

Strengthening Effect ◽

Term Strength ◽

Test Results ◽

Creep Constitutive Model

The triaxial creep tests of frozen silty clay mixed with sands were performed under different pressures, and the test results demonstrated that, under the low confining pressure, when the shear stress is lower than the long-term strength, the test specimen exhibits an attenuation creep because the strengthening effect is greater than the weakening effect. When the shear stress is higher than the long-term strength, the test specimen exhibits a nonattenuation creep due to the level of the strengthening and weakening effects change in different stages. As the confining pressure increases, the test specimens only exhibit an attenuation creep because of the enhancing strengthening effect. Both the hardening parameter and the damage variable were introduced to describe the strengthening and weakening effects, respectively, and a new creep constitutive model for frozen soil considering these effects was put forward based on the theory of elastoviscoplastic and the fractional derivative. Finally, the model parameters were analyzed and their determination method was also provided to reveal the trend of parameters according to the triaxial test results. The calculated results of the constitutive model show that the proposed model can describe the whole creep process of frozen soil well.

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Experimental Study on Direct Shear Creep Characteristics and Long-Term Strength of Red Layer Sliding Zone Soil in Southern Hunan

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.842.782 ◽

2013 ◽

Vol 842 ◽

pp. 782-787 ◽

Cited By ~ 1

Author(s):

Feng Zhu ◽

Zhong Yuan Duan ◽

Zhen Yu Wu ◽

Yu Qi Wu ◽

Tian Long Li ◽

...

Keyword(s):

Shear Stress ◽

Term Strength ◽

Direct Shear ◽

Creep Tests ◽

Shear Creep ◽

Creep Characteristics ◽

Southern Hunan ◽

Sliding Soil ◽

Sliding Zone

The creep characteristics of red layer sliding soil under the condition of different vertical loads and water contents were studied through a series of direct shear creep tests. Tests results showed that the water infiltrated to the sliding zone along the fissure of red layer sliding belt due to the crush of red layer sliding rock, leading to softening of sliding zone and acceleration of shear creep. When the shear stress reached the limit of long-term shear strength, sliding soil was broken suddenly with small vertical loads (50 kPa and 100kPa), while the sliding soil presented as a constant acceleration creep with enough vertical loads (200 kPa and 300 kPa). The inflection point in shear stress-shear displacement isochronous curve corresponded to the long-term strength of the soil.

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LONG TERM STRENGTH CHARACTERISTIC OF CEMENT-TREATED AND HIGH-PRESSURE-DEHYDRATED SOIL BLOCK

Journal of Japan Society of Civil Engineers Ser B3 (Ocean Engineering) ◽

10.2208/jscejoe.76.2_i_630 ◽

2020 ◽

Vol 76 (2) ◽

pp. I_630-I_635

Author(s):

Kazutaka UENO ◽

Kiyonobu KASAMA ◽

Yasuyuki NAKAGAWA ◽

Yasuhiro SEGA ◽

Masaharu MINAMI ◽

...

Keyword(s):

High Pressure ◽

Strength Characteristic ◽

Term Strength ◽

Soil Block

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Effects of high pressure on the crystallization of carbon fiber reinforced polyetheretherketone (CF/PEEK) laminate composites

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100177519 ◽

1990 ◽

Vol 48 (4) ◽

pp. 876-877

Author(s):

Hong-Ming Lin ◽

C. H. Liu ◽

R. F. Lee

Keyword(s):

High Pressure ◽

Carbon Fiber ◽

Sample Surface ◽

High Yield ◽

Fiber Reinforced ◽

Laminate Composites ◽

Peek Composite ◽

Continuous Carbon Fiber ◽

Carbon Fiber Reinforced

Polyetheretherketone (PEEK) is a crystallizable thermoplastic used as composite matrix materials in application which requires high yield stress, high toughness, long term high temperature service, and resistance to solvent and radiation. There have been several reports on the crystallization behavior of neat PEEK and of CF/PEEK composite. Other reports discussed the effects of crystallization on the mechanical properties of PEEK and CF/PEEK composites. However, these reports were all concerned with the crystallization or melting processes at or close to atmospheric pressure. Thus, the effects of high pressure on the crystallization of CF/PEEK will be examined in this study.The continuous carbon fiber reinforced PEEK (CF/PEEK) laminate composite with 68 wt.% of fibers was obtained from Imperial Chemical Industry (ICI). For the high pressure experiments, HIP was used to keep these samples under 1000, 1500 or 2000 atm. Then the samples were slowly cooled from 420 °C to 60 °C in the cooling rate about 1 - 2 degree per minute to induce high pressure crystallization. After the high pressure treatment, the samples were scanned in regular DSC to study the crystallinity and the melting temperature. Following the regular polishing, etching, and gold coating of the sample surface, the scanning electron microscope (SEM) was used to image the microstructure of the crystals. Also the samples about 25mmx5mmx3mm were prepared for the 3-point bending tests.

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