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

2013 ◽  
Vol 842 ◽  
pp. 782-787 ◽  
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.

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

2011 ◽  
Vol 105-107 ◽  
pp. 832-836 ◽  
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.

scholarly journals Effect of Moisture Content On The Time-Dependent Mechanical Characteristics of Loess

2021 ◽  
Author(s):  
Lijie Chen ◽  
Jianbing Peng ◽  
Fei Xie ◽  
Yanqiu Leng ◽  
Penghui Ma ◽  
...  
Keyword(s):  
Moisture Content ◽  
Failure Mode ◽  
Shear Failure ◽  
Time Dependent ◽  
Shanxi Province ◽  
Peak Strain ◽  
Term Strength ◽  
Creep Tests ◽  
Effect Of Moisture

Abstract It is of great significance to study the time-dependent mechanical properties of loess, as loess landslides are closely related to them. The purpose of this study is to investigate the effect of moisture content on instantaneous and time-dependent deformation, strength and failure behaviors of undisturbed loess specimens from Nangou in Yan'an City, Shanxi Province, China, via triaxial shearing tests and multi-loading triaxial creep tests under moisture contents of 5%, 10%, 17% and 22%. The results show that the time-dependent deformation of loess increase with the moisture content, while the time-dependent deformation rate decreases slowly. The soil deformation is divided into four stages based on the peak strain rate. Furthermore, the instantaneous and long-term strength of loess decrease with increasing moisture content, and the instantaneous strength decreases more than the long-term strength. The failure mode of undisturbed loess changes from shear failure to homogeneous failure with increasing moisture content; when the failure mode is shear failure, the thickness of the shear band that forms at the specimen surface over time is smaller than the corresponding thickness that forms instantaneously. Finally, the macroscopic morphology and microstructure of loess specimens were considered together to analyze the effect of moisture content on the instantaneous and long-term mechanical behavior of loess and to discuss the process of loess deformation to failure.

An Empirical Constitutive Correlation for Regular Jugged Discontinuity of Rock Surfaces

2013 ◽  
Vol 5 (2) ◽  
pp. 258-268 ◽  
Author(s):  
Bin Yang ◽  
Sihao Mo ◽  
Ping Wu ◽  
Chaoqing He
Keyword(s):  
Deformation Property ◽  
Creep Property ◽  
Shear Stresses ◽  
Test Results ◽  
Creep Tests ◽  
Shear Creep ◽  
Burger Model ◽  
Structural Plane ◽  
Creep Velocity

AbstractThis paper presents a physical investigation and mathematical analysis on mechanical behavior of the regular jugged discontinuity. In particular, we focus on the creep property of structural plane with various slope angles under different normal stress through shear creep tests of structural plane under shear stresses. According to the test results, the shear creep property of structural plane was described and the creep velocity and long-term strength of the structural plane during shear creep were also investigated. An empirical formula is finally established to evaluate shear strength of discontinuity and a modified Burger model was proposed to represent the shear deformation property during creep.

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

2016 ◽  
Vol 2016 ◽  
pp. 1-12 ◽  
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.

Simple shear creep tests on frozen soils

1981 ◽  
Vol 18 (2) ◽  
pp. 217-229 ◽  
Author(s):  
J. S. Weaver ◽  
N. R. Morgenstern
Keyword(s):  
Simple Shear ◽  
Load Transfer ◽  
Creep Tests ◽  
Shear Creep ◽  
Frozen Soils ◽  
Creep Properties ◽  
Uniform Shear ◽  
Direct Simple Shear ◽  
Applied Shear Stress

Direct simple shear tests have been conducted on a variety of reconstituted frozen soils and on ice in order to investigate the load transfer process associated with the adfreeze bond to piles, and to obtain creep properties of frozen soils. The test develops uniform shear strain between plates of different roughnesses provided the applied shear stress is less than the ad freeze strength of the pile. Tests have been performed at about −1°C for durations up to 45 days to explore ultimate creep rates. The long-term flow of ice in this test is consistent with previously published power law relations. The experimental data on the frozen soils indicate how creep rate tends to decrease with increasing density except for dirty ice, which displays creep rates slightly higher than those observed for pure ice.

scholarly journals Experimental Study on Shear Stress-Displacement, Creep and Shear Slip Instability Behavior of Rock Fractures

2021 ◽  
Author(s):  
Minglei Zhai ◽  
Haibo Bai
Keyword(s):  
Shear Stress ◽  
Rock Mass ◽  
Shear Loading ◽  
Shear Displacement ◽  
Rock Fractures ◽  
Shear Tests ◽  
Creep Tests ◽  
Shear Creep ◽  
Cyclic Shear ◽  
Multistage Loading

Abstract Rock mass inherently contains discontinuities, and shear sliding of rock masses along discontinuities is the most common failure mode of rock mass in engineering practice (such as slope, dam and tunnel). In this study, the mechanical and failure properties of rock fractures were examined through direct shear tests, pre-peak tiered cyclic shear tests and multistage loading shear creep tests. The results show that the deformable memory of rocks can be observed from shear stress-shear displacement curves, namely reloading curves continued to increase along the loading curve of the last cycle under the pre-peak tiered cyclic shear loading. The envelopes of shear stress-shear displacement curves were similar to the variation trend of shear stress-shear displacement curves obtained in the direct shear test. Besides, the variation trend of residual shear displacement (RSD) and relative residual shear displacement (RRSD) before slip instability were obtained by the data analyses of rock mass under pre-peak tiered cyclic shear tests. It is found that the change in the friction and sliding state of rock fracture is the main reason for the fluctuation of shear stress-shear displacement curves. The Chen's method was used to process the multistage loading shear creep curves and the three creep stages were analyzed. Moreover, the complex creep models in some previous studies were discussed and the data of shear creep tests were successfully fitted to the classical Burgers model. This study provides a guidance for the study on the shear instability of rock fractures under different shear loading paths.

scholarly journals Experimental Researches on Long-Term Strength of Granite Gneiss

2015 ◽  
Vol 2015 ◽  
pp. 1-9 ◽  
Author(s):  
Lin Liu ◽  
Weiya Xu
Keyword(s):  
Quantitative Methods ◽  
Strain Curve ◽  
Granite Gneiss ◽  
Term Strength ◽  
Creep Tests ◽  
New Methods ◽  
Tangent Method ◽  
Triaxial Creep ◽  
Triaxial Creep Tests

It is important to confirm the long-term strength of rock materials for the purpose of evaluating the long-term stability of rock engineering. In this study, a series of triaxial creep tests were conducted on granite gneiss under different pore pressures. Based on the test data, we proposed two new quantitative methods, tangent method and intersection method, to confirm the long-term strength of rock. Meanwhile, the isochronous stress-strain curve method was adopted to make sure of the accuracy and operability of the two new methods. It is concluded that the new methods are suitable for the study of the long-term strength of rock. The effect of pore pressure on the long-term strength of rock in triaxial creep tests is also discussed.

Experimental Research on Creep Laws of High-Water Material under Real Pressure Water Environment

2016 ◽  
Vol 705 ◽  
pp. 350-354
Author(s):  
Hui Xie ◽  
Ying Chen
Keyword(s):  
Experimental Research ◽  
Carrying Capacity ◽  
Water Pressure ◽  
Water Environment ◽  
High Water ◽  
Term Strength ◽  
Steady Creep ◽  
Creep Tests ◽  
Pressure Water

High-water material is a kind of new inorganic nonmetal material which mainly used in coal mine goaf filling. In order to simulate the real stress conditions of this material in goaf filling, the creep tests of high-water material in real pressure water environment were conducted and the creep laws were also researched. The results showed that water environment was conductive to maintaining and developing the strength of high-water material, and pressure water environment can improve the carrying capacity and long-term strength of high-water material. The deformation of steady creep period decreased while water pressure increased. And strain increasing caused by axial compression was less than strain increasing caused by water pressure. The time needed from starting to steady creep period was longer when water pressure was bigger.

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

2019 ◽  
Vol 2019 ◽  
pp. 1-18 ◽  
Author(s):  
Jinbo Jia ◽  
Yansen Wang ◽  
Yangguang Leng
Keyword(s):  
High Pressure ◽  
Creep Property ◽  
Frozen Soil ◽  
Soil Parameters ◽  
Unfrozen Water ◽  
Term Strength ◽  
Creep Characteristics ◽  
Frozen Clay ◽  
Consolidation Time

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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