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.

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.

Research on Shear Creep Property of Soft Rock in Dam Foundation

2011 ◽  
Vol 243-249 ◽  
pp. 2744-2747
Author(s):  
Yu Wang ◽  
Hua Feng Deng ◽  
Tao Lu ◽  
Zong Yong Zhao
Keyword(s):  
Soil Mechanics ◽  
Testing Machine ◽  
Creep Property ◽  
Soft Rock ◽  
Shear Creep ◽  
Dam Foundation ◽  
Creep Characteristic ◽  
The Stability ◽  
Argillaceous Siltstone

Creep characteristic is one of the most important mechanical characteristics of rock. It controls the stability of rock engineering. Under step load conditon, the shear creep test of argillaceous siltstone which was collected in dam foundation is performed by using the RMT150c rock and soil mechanics testing machine. The shear creep curves under different normal stresses show that the argillaceous siltstone is very significant in creep, which should be considered in the stability analysis of dam foundation. According to the analysis of experimental results, the long-term shear strength parameters are determined to provide reference for engineering survey and design.

scholarly journals How Nanoscale Dislocation Reactions Govern Low- Temperature and High-Stress Creep of Ni-Base Single Crystal Superalloys

Crystals ◽  
2020 ◽  
Vol 10 (2) ◽  
pp. 134 ◽  
Author(s):  
David Bürger ◽  
Antonin Dlouhý ◽  
Kyosuke Yoshimi ◽  
Gunther Eggeler
Keyword(s):  
Low Temperature ◽  
Single Crystal ◽  
High Stress ◽  
Shear Stresses ◽  
Creep Tests ◽  
Shear Creep ◽  
Tem Analysis ◽  
Transmission Electron ◽  
Crystallographic Shear ◽  
Shear System

The present work investigates γ-channel dislocation reactions, which govern low-temperature (T = 750 °C) and high-stress (resolved shear stress: 300 MPa) creep of Ni-base single crystal superalloys (SX). It is well known that two dislocation families with different b-vectors are required to form planar faults, which can shear the ordered γ’-phase. However, so far, no direct mechanical and microstructural evidence has been presented which clearly proves the importance of these reactions. In the mechanical part of the present work, we perform shear creep tests and we compare the deformation behavior of two macroscopic crystallographic shear systems [ 01 1 ¯ ] ( 111 ) and [ 11 2 ¯ ] ( 111 ) . These two shear systems share the same glide plane but differ in loading direction. The [ 11 2 ¯ ] ( 111 ) shear system, where the two dislocation families required to form a planar fault ribbon experience the same resolved shear stresses, deforms significantly faster than the [ 01 1 ¯ ] ( 111 ) shear system, where only one of the two required dislocation families is strongly promoted. Diffraction contrast transmission electron microscopy (TEM) analysis identifies the dislocation reactions, which rationalize this macroscopic behavior.

scholarly journals Improved Nonlinear Nishihara Shear Creep Model with Variable Parameters for Rock-Like Materials

2020 ◽  
Vol 2020 ◽  
pp. 1-15 ◽  
Author(s):  
Hang Lin ◽  
Xing Zhang ◽  
Yixian Wang ◽  
Rui Yong ◽  
Xiang Fan ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Shear Strength ◽  
Creep Test ◽  
Creep Property ◽  
Variable Parameter ◽  
Nonlinear Function ◽  
Creep Model ◽  
Creep Process ◽  
Shear Creep

Creep property is an important mechanical property of rocks. Given the complexity of rock masses, mechanical parameters change with time in the creep process. In this work, a nonlinear function for describing the time-dependent change of parameters was introduced and an improved variable-parameter nonlinear Nishihara shear creep model of rocks was established. By creating rock-like materials, the mechanical properties of rocks under the shear creep test condition were studied, and the deformation characteristics and long-term shear strength of rocks during creep were analyzed. The material parameters of the model were identified using the creep test results. Comparison of the model’s calculated values and experimental data indicated that the model can describe the creep characteristics of rocks well, thus proving the correctness and rationality of the improved model. During shear creep, the mechanical properties of rocks have an aging effect and show hardening characteristics under low shear stress. Furthermore, according to the fact that Gk of the nonlinear model can characterize the creep deformation resistance, a method to determine the long-term shear strength is proposed.

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.

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.

Research on Creep Property of Cement Grouted Joint

2011 ◽  
Vol 243-249 ◽  
pp. 2819-2824
Author(s):  
Fu Ting Sun ◽  
Cheng Xue She ◽  
Kun Li
Keyword(s):  
Normal Stress ◽  
Creep Test ◽  
Creep Property ◽  
Test Results ◽  
Shear Creep ◽  
Joint Roughness ◽  
Multi Stage ◽  
Elastic Shear ◽  
Theoretical Results ◽  
Good Coincidence

The creep property of cement grouted joint is studied based on creep test and theoretical analysis. Firstly, the multi-stage shear creep test under constant normal stress, joint roughness and cement filled thickness is carried out to obtain the creep deformation. Then the conventional linear Nishihara model is used to fit the test results. Due to the big deviation of the theoretical results from the test, the instantaneous elastic shear stiffnesses under different loading stages are calculated. It is found that they vary with the shear stress. The reasons for the nonlinearity are analyzed. Finally the parameters of the Nishihara model are modified to be nonlinear and fit with the test results showing good coincidence between them. These researches release the creep property of the cement grouted joint, and will provide a good basis for further research considering more influencing factors such as normal stress, joint roughness and cement filled thickness.

scholarly journals A Long Term Shear Test for Orthotropic Composites

1993 ◽  
Vol 2 (5) ◽  
pp. 096369359300200
Author(s):  
A Yoosefinejad ◽  
P J Hogg
Keyword(s):  
Shear Test ◽  
Test Method ◽  
Test Results ◽  
Initial Test ◽  
Short Term ◽  
Shear Creep ◽  
Orthotropic Composites ◽  
Short Term Test ◽  
Properties Of Composites

A new test method is presented that is considered suitable for measuring the long term mechanical properties of composites loaded in shear. The test method is assessed for its reproducibility and accuracy and compared to conventional Iosipescu tests for short term test results. Some initial test data for long term shear creep are also presented

scholarly journals Creep Resistance of VM12 Steel

2016 ◽  
Vol 61 (3) ◽  
pp. 1635-1640 ◽  
Author(s):  
A. Zieliński ◽  
G. Golański ◽  
J. Dobrzański ◽  
M. Sroka
Keyword(s):  
Functional Properties ◽  
Creep Test ◽  
Creep Resistance ◽  
Practical Aspect ◽  
Test Results ◽  
Creep Tests ◽  
Steam Parameters ◽  
Term Creep ◽  
Long Term Impact

Abstract This article presents selected material characteristics of VM12 steel used for elements of boilers with super- and ultra-critical steam parameters. In particular, abridged and long-term creep tests with and without elongation measurement during testing and investigations of microstructural changes due to long-term impact of temperature and stress were carried out. The practical aspect of the use of creep test results in forecasting the durability of materials operating under creep conditions was presented. The characteristics of steels with regard to creep tests developed in this paper are used in assessment of changes in functional properties of the material of elements operating under creep conditions.

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