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.

Permeability Evolution of Granite Gneiss During Triaxial Creep Tests

2016 ◽  
Vol 49 (9) ◽  
pp. 3455-3462 ◽  
Author(s):  
L. Liu ◽  
W. Y. Xu ◽  
H. L. Wang ◽  
W. Wang ◽  
R. B. Wang
Keyword(s):  
Granite Gneiss ◽  
Permeability Evolution ◽  
Creep Tests ◽  
Triaxial Creep ◽  
Triaxial Creep Tests

scholarly journals An Experimental Study on the Creep Characteristics of Sandstone in the Interval of Different Critical Stresses

2021 ◽  
Vol 2021 ◽  
pp. 1-8
Author(s):  
Chao Yang ◽  
Xingchen Dong ◽  
Xuan Xu ◽  
Qiancheng Sun
Keyword(s):  
Failure Time ◽  
Strain Curve ◽  
Creep Model ◽  
Creep Process ◽  
Term Strength ◽  
Creep Tests ◽  
Critical Stresses ◽  
Brittle Sandstone ◽  
Time Required

Creep tests on brittle sandstone specimens were performed to investigate the time-dependent characteristics in the interval of different critical stresses. The results showed that failure will not occur when the loaded stress σ1 is less than the critical stress of dilation σcd, while all specimens were destroyed when σ1 is larger than σcd. In addition, the value of σcd was very close to the long-term strength obtained by the method of the isochronous stress-strain curve. Therefore, σcd can be regarded as the long-term strength of the sandstone specimens. When σ1 is larger than σcd, the time required for the failure of specimen tf decreases with the increase of σ1; the creep rate dε/dt increases with time t, and the specimen will be destroyed when it reaches a maximum value (dε/dt)max. Both relationships tf and σ1 and (dε/dt)max and σ1 can be described by the exponential function. Then, a nonlinear damage creep model considering the deformation damage and strength damage in the interval of different critical stresses was established, which can describe the whole creep process and predict the failure time of sandstone specimens.

An Experimental Study on the Creep of FRC Sub-Base for Pavement Using a New Testing Device

2013 ◽  
Vol 639-640 ◽  
pp. 493-497
Author(s):  
Woo Tai Jung ◽  
Sung Yong Choi ◽  
Young Hwan Park
Keyword(s):  
Creep Test ◽  
Strain Curve ◽  
Hydraulic Pressure ◽  
Slight Variation ◽  
Test Results ◽  
Creep Tests ◽  
Loading Device ◽  
Permanent Load ◽  
Term Creep

The hydraulic loading device commonly used for creep test necessitates continuous recharge of the hydraulic pressure with time and is accompanied by slight variation of the permanent load at each recharge. Therefore, accurate test results cannot be obtained for long-term creep tests requiring time-dependent behavioral analysis during more than 6 months. This study conducts creep test as part of the analysis of the long-term characteristics of fiber-reinforced lean concrete sub-base of pavement. The creep test is executed using the new load-amplifier device not a conventional loading device. Since the results of the preliminary verification test on the new creep test device show that constant permanent load is applied without significant variation, it can be expected that more accurate measurement of the creep will be possible in a long-term compared to the conventional hydraulic device. In addition, the creep test results of sub-base specimens reveal the occurrence of large instantaneous elastic strain, differently from the strain curve observed in ordinary concrete, as well as the occurrence of small creep strain leading to low creep coefficient.

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.

A NONLINEAR VISCOELASTIC-PLASTIC RHEOLOGICAL MODEL FOR ROCKS BASED ON FRACTIONAL DERIVATIVE THEORY

2013 ◽  
Vol 27 (25) ◽  
pp. 1350149 ◽  
Author(s):  
HONGJIE CHEN ◽  
WEIYA XU ◽  
WEI WANG ◽  
RUBIN WANG ◽  
CHONG SHI
Keyword(s):  
Rheological Model ◽  
Soft Matter ◽  
Fractional Derivatives ◽  
High Stress ◽  
Creep Tests ◽  
Creep Stage ◽  
Accelerated Creep ◽  
Triaxial Creep ◽  
Triaxial Creep Tests ◽  
The Ideal

The soft-matter element between the ideal solid and the ideal liquid is established and is described based on the definition of the fractional derivatives. By replacing a component in the generalized Kelvin model with the soft-matter component and connecting it in series with a nonlinear visco-plastic body, a nonlinear viscoelasto-plastic rheological model is proposed based on the fractional derivatives in order to describe the rheological behaviors of rocks. The data obtained from the triaxial creep tests of a typical rock are simulated with this model and the fitting result is good. The model can describe well three rheological stages of the rock during the triaxial creep tests. The validity of this model is then discussed. In this model, the fractional order β controls creep strain rate in the stable creep stage under the condition of low stress; while the creep index n controls creep rate of the accelerated rheological stage under the condition of high stress. Few parameters and good simulation results manifest the outstanding performance of the model. The model also adopts the damage theory to describe the progressive deterioration of rock viscous coefficient of the accelerated creep stage. The model can also give an excellent description of the three rheological stages of rocks, especially the accelerated creep stage.

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