scholarly journals A Test Method for Creep Characteristics of Loess Based on the One-Dimensional Consolidator

2021 ◽  
Vol 2021 ◽  
pp. 1-10
Author(s):  
Rongbin Huang ◽  
Shuangming Wang ◽  
Shuancheng Gu ◽  
Zhengjun Mao
Keyword(s):  
Influence Factors ◽  
Test Method ◽  
Creep Process ◽  
Deformation And Failure ◽  
Creep Stage ◽  
One Dimensional ◽  
Process Characteristics ◽  
Whole Process ◽  
Creep Characteristics ◽  
Accelerated Creep

When the traditional one-dimensional consolidator is used to study the creep characteristics of loess, due to the hoop effect of the ring cutter, only the attenuation creep stage and stable creep stage of loess can be studied, but the accelerated creep stage cannot be presented. In order to avoid the influence of drilling on the creep characteristics of loess, the paper improves the consolidation instrument by drilling holes along the diameter direction in the center of the sample to provide artificial space for soil failure. At the same time, the sample size is increased to ensure that the diameter of the sample is greater than five times of the diameter of the borehole, so as to avoid the influence of drilling on the creep characteristics of loess. The creep characteristics of loess are studied by step loading (vertical pressure at all levels is 125 kPa, 175 Pa, 225 kPa, and 275 kPa), and the whole creep process characteristic curves of loess under different stress conditions are obtained. An endoscope was placed in the hole to observe the deformation and failure characteristics of loess in different stages of creep. This method makes up for the defect that the traditional one-dimensional consolidator cannot obtain the whole process characteristics of loess creep. At the same time, it has the advantages of simple operation, less external influence factors, stronger data reliability, and can directly observe the changes of loess creep soil. It has a beneficial role in promoting the experimental research of loess creep characteristics.

scholarly journals A Study on the Creep Characteristics of Airport Viscous Subsoil Based on Unsaturated Stress Level

Geofluids ◽  
2021 ◽  
Vol 2021 ◽  
pp. 1-13
Author(s):  
Jun Feng ◽  
Yue Ma ◽  
Zaobao Liu
Keyword(s):  
Stress Level ◽  
Unsaturated Soil ◽  
Three Dimensional ◽  
Matric Suction ◽  
Creep Model ◽  
Creep Stage ◽  
One Dimensional ◽  
Creep Characteristics ◽  
Stress Levels ◽  
The One

The present study takes the ratio of the matric suction to the net vertical stress and the ratio of the matric suction to the net mean stress as new unsaturated stress levels f and F , respectively. Based on the laboratory tests and theoretical derivation, the modified one-dimensional Mesri creep model and three-dimensional creep model were established, which takes the unsaturated stress level into account. Then, the one-dimensional and three-dimensional creep characteristics of the unsaturated viscous subsoil of an airport under different unsaturated stress levels were analyzed. The following conclusions could be drawn: (1) under different stress levels, the one-dimensional creep deformation of unsaturated soil has a power function relationship with time, and the change rate exponentially decreases with the stress level, which can be well-expressed by the proposed modified one-dimensional Mesri creep model; (2) under different stress levels, the three-dimensional creep strain of the unsaturated soil shows a hyperbolic curve with time and a near-linear relationship at the semilogarithmic coordinate, which can be well-expressed by the proposed modified three-dimensional creep model; (3) under different stress levels, both the one-dimensional creep and three-dimensional creep of the unsaturated soil can be divided into two stages, which are the accelerated creep stage and stable creep stage.

Investigation on Creep Characteristics of Rock-Like with Precast Internal Fissures under Different Temperatures and Confining Pressures

2021 ◽  
Vol 1032 ◽  
pp. 120-125
Author(s):  
Peng Du ◽  
Yong Yan Wang
Keyword(s):  
Failure Time ◽  
High Stress ◽  
Confining Pressure ◽  
Tensile Failure ◽  
Effect Of Temperature ◽  
Creep Process ◽  
Creep Stage ◽  
Accelerated Creep ◽  
Different Temperatures ◽  
Confining Pressures

In order to study the effect of temperature-confining pressure coupling on the creep behavior of rock-like specimen with precast internal fissures, the creep tests under different temperatures and confining pressures are carried out. The test results show that the rock presents primary creep stage and steady creep stage at low stress levels. Under the condition of high stress, the creep process of rock shows an obvious accelerated creep stage. The curve of accelerated creep stage of rock gradually smoothing with the increase of confining pressure, and the corresponding creep failure time gradually increases. The failure under low confining pressure is mainly tensile failure. The high confining pressure is the shear failure, or even the mixture of shear and plastic failure.

Investigation on Creep Mechanism of a Ni3Al-Based Single Crystal Superalloy IC6SX under 760°C/540MPa

2013 ◽  
Vol 747-748 ◽  
pp. 804-809 ◽  
Author(s):  
Li Wu Jiang ◽  
Shu Suo Li ◽  
Mei Ling Wu
Keyword(s):  
Electron Microscopy ◽  
Single Crystal ◽  
Creep Mechanism ◽  
Single Crystal Superalloy ◽  
Creep Process ◽  
Dislocation Configuration ◽  
Creep Stage ◽  
Dislocation Glide ◽  
Accelerated Creep ◽  
Testing Condition

The creep behaviors of a Ni3Al-base single crystal superalloy IC6SX prepared by spiral grain selection method was studied systematically under the testing condition of 760/540MPa. The microstructure evolution, movement of dislocations, formation of the dislocation networks and dislocation configuration during the creep process were investigated by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The results showed that the creep performance of the single crystal alloy IC6SX is excellent under 760/540MPa. The experimental results showed that the creep curve of the Ni3Al-base single crystal superalloy IC6SX was divided into three stages, including decelerating creep stage, steady-state creep stage and accelerated creep stage. The microstructure and the dislocation configuration were different at different stage during the creep and the raft microstructure has not been formed. The creep mechanism was main slipping characterized by dislocation glide mechanism.

Study on the generalized k-Hilfer–Prabhakar fractional viscoelastic–plastic model

2021 ◽  
pp. 108128652110258
Author(s):  
Yi-Ying Feng ◽  
Xiao-Jun Yang ◽  
Jian-Gen Liu ◽  
Zhan-Qing Chen
Keyword(s):  
Constitutive Model ◽  
Three Dimensional ◽  
Sensitivity Analyses ◽  
Creep Process ◽  
Fractional Operator ◽  
Modified Model ◽  
Proposed Model ◽  
Accelerated Creep ◽  
The Laplace Transform ◽  
Classical Models

The general fractional operator shows its great predominance in the construction of constitutive model owing to its agility in choosing the embedded parameters. A generalized fractional viscoelastic–plastic constitutive model with the sense of the k-Hilfer–Prabhakar ( k-H-P) fractional operator, which has the character recovering the known classical models from the proposed model, is established in this article. In order to describe the damage in the creep process, a time-varying elastic element [Formula: see text] is used in the proposed model with better representation of accelerated creep stage. According to the theory of the kinematics of deformation and the Laplace transform, the creep constitutive equation and the strain of the modified model are established and obtained. The validity and rationality of the proposed model are identified by fitting with the experimental data. Finally, the influences of the fractional derivative order [Formula: see text] and parameter k on the creep process are investigated through the sensitivity analyses with two- and three-dimensional plots.

Determination of soil water hydraulic parameters from infiltration data

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Yan Gao ◽  
Kai Chang ◽  
Xuguang Xing ◽  
Jiaping Liang ◽  
Nian He ◽  
...  
Keyword(s):  
Soil Water ◽  
Water Retention ◽  
Test Method ◽  
Water Retention Curve ◽  
Absorption Method ◽  
Retention Curve ◽  
Content Type ◽  
One Dimensional ◽  
Water Diffusivity

PurposeTraditional laboratory measurements of soil water diffusivity (D) and soil water retention curve (SWRC) are always time-consuming and labor-intensive. Therefore, this paper aims to present a simple and robust test method for determining D and SWRC without reducing accuracy.Design/methodology/approachIn this study, a D model of unsaturated soil was established based on Gardner–Russo model and then a combination of Gardner–Russo model with one-dimensional horizontal absorption method to obtain n and a parameters of Gardner–Russo model. One-dimensional horizontal absorption experiments on loam, silt loam and sandy clay loam were conducted to obtain the relationships between measured infiltration rate and cumulative infiltration with wetting front distance. Based on the obtained relationships, the measured infiltration data from the one-dimensional horizontal absorption tests were used to calculate n and a parameters and further constructing D and SWRC.FindingsBoth the calculated D and SWRC inversed from the infiltration data were in good agreement with the measured ones that obtained from the traditional horizontal absorption method and the centrifuge method, respectively. Error analysis indicated that only the infiltration data are enough to reliably synchronously determine D and SWRC.Originality/valueA simple and robust method is proposed for synchronous determination of soil water diffusivity and water retention curve.

Creep Characteristics Analysis of Oil Shale and its Application

2010 ◽  
Vol 29-32 ◽  
pp. 2614-2619 ◽  
Author(s):  
Jun Guang Wang ◽  
Bing Liang
Keyword(s):  
Oil Shale ◽  
Stability Control ◽  
Creep Model ◽  
Test Results ◽  
Creep Properties ◽  
Creep Stage ◽  
Creep Characteristics ◽  
Roadway Stability ◽  
Theoretical Significance ◽  
Characteristics Analysis

to study oil shale creep properties, we use rock SJ-1B three-axis creep instrument on oil shale to carry three axis creep test. Through test results, the creep of oil shale is nonlinear, and in accelerating creep stage oil shale injury increased dramatically. Using Burgers creep model introduced damage variable to analyse the oil shale surrounding stress and displacement field and Systematically analyse the creep properties under various support intensity. So it has important theoretical significance and value for the oil shale resource development and roadway stability control.

Full-Field Displacement and Strain Measurement: Application of Digital Image Correlation to Reinforcement Corrosion Induced Concrete Fracture and Cover Cracking

2015 ◽  
Vol 738-739 ◽  
pp. 889-892
Author(s):  
Qiang Li ◽  
Hong Fa Yu ◽  
Jing Tong
Keyword(s):  
Reinforced Concrete ◽  
Steel Corrosion ◽  
Test Method ◽  
Image Correlation ◽  
Concrete Fracture ◽  
Reinforcement Corrosion ◽  
Full Field ◽  
Rc Structures ◽  
Whole Process ◽  
Cover Cracking

Cracking of the cover concrete due to steel corrosion is considered as one of the major issues of durability of reinforced concrete (RC) structures. This paper tentatively studies the feasibility of DIC to reinforcement corrosion induced concrete fracture and cover cracking measurement. Advantages and limitations of DIC-based non-contact full-field measurement for corrosion induced concrete fracture and cover cracking are discussed. Drawbacks in this test need improvement are pointed out and test method for further study of whole process of simulating the real reinforced concrete cracking is put forward.

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