Proposal of a new rock creep model

2014 ◽  
pp. 137-141 ◽  
Author(s):  
V Brotóns ◽  
S Ivorra ◽  
R Tomás ◽  
J Martínez-Martínez ◽  
D Benavente
Keyword(s):  
Creep Model ◽  
Rock Creep

scholarly journals Nonlinear Viscoelastic-Plastic Creep Model of Rock Based on Fractional Calculus

2022 ◽  
Vol 2022 ◽  
pp. 1-7
Author(s):  
Erjian Wei ◽  
Bin Hu ◽  
Jing Li ◽  
Kai Cui ◽  
Zhen Zhang ◽  
...  
Keyword(s):  
Fractional Calculus ◽  
Fractional Order ◽  
Engineering Application ◽  
Creep Model ◽  
Nonlinear Viscoelastic ◽  
Rock Creep ◽  
Order Change ◽  
Creep Constitutive Model ◽  
Plastic Creep

A rock creep constitutive model is the core content of rock rheological mechanics theory and is of great significance for studying the long-term stability of engineering. Most of the creep models constructed in previous studies have complex types and many parameters. Based on fractional calculus theory, this paper explores the creep curve characteristics of the creep elements with the fractional order change, constructs a nonlinear viscoelastic-plastic creep model of rock based on fractional calculus, and deduces the creep constitutive equation. By using a user-defined function fitting tool of the Origin software and the Levenberg–Marquardt optimization algorithm, the creep test data are fitted and compared. The fitting curve is in good agreement with the experimental data, which shows the rationality and applicability of the proposed nonlinear viscoelastic-plastic creep model. Through sensitivity analysis of the fractional order β2 and viscoelastic coefficient ξ2, the influence of these creep parameters on rock creep is clarified. The research results show that the nonlinear viscoelastic-plastic creep model of rock based on fractional calculus constructed in this paper can well describe the creep characteristics of rock, and this model has certain theoretical significance and engineering application value for long-term engineering stability research.

The Rock Creep Evaluation in the Analysis System for the Long-Term Behavior of TRU Waste Disposal System

2009 ◽  
Author(s):  
Shintaro Ohno ◽  
Seiji Morikawa ◽  
Morihiro Mihara
Keyword(s):  
Mechanical Behavior ◽  
Waste Disposal ◽  
Creep Model ◽  
Elastic Behavior ◽  
Elastic Model ◽  
Barrier Materials ◽  
Rock Creep ◽  
Cement Based Materials ◽  
Analysis System

MACBECE (Mechanical Analysis system considering Chemical transitions of BEntonite-based and CEment-based materials) is an analysis system to evaluate the long term mechanical behavior in the TRU (TRans Uranium) waste disposal system. TRU wastes are low level radioactive wastes that include long-lived nuclides. MACBECE is the system to calculate mechanical and chemical behavior in the near field including engineered barriers in the TRU waste disposal system, and subsequently to evaluate the hydraulic property in various components. MACBECE can evaluate the mechanical/ hydraulic alterations of two types of barrier materials, cement-based and bentonite-based materials. These materials, in the long-term, may be altered internally by chemical reaction. To evaluate the long-term mechanical behavior due to the chemical transitions, the nonlinear elastic model for the cement-based materials and the elasto-viscoplastic model for the bentonite-based materials were applied, based on the data from various laboratory tests. Also, proposed models based on the data from permeability tests were applied to evaluate the alteration of hydraulic conductivity. So as to realize the high reliable evaluation, the variable-compliance-type constitutive model proposed by Okubo (1992) was newly adopted for the rock creep evaluation in MACBECE. This creep model can express analytically nonlinear visco-elastic behavior and the over-peak-strength state behavior. This paper focuses on the adoptability of rock creep model in MACBECE. Applicability of the rock creep model is verified by conducting the numerical simulations with the long-term mechanical interaction between the TRU waste disposal system and the host rock.

Research on Construction and Operation Parameters of an Underground Oil Storage in Depleted Salt Caverns in the East of China

2021 ◽  
Author(s):  
Fu Jin ◽  
Wang Xi ◽  
Ding Mingming ◽  
Yang Guobin ◽  
Zhang Shunyuan ◽  
...  
Keyword(s):  
Crude Oil ◽  
Internal Pressure ◽  
Flow Rate ◽  
Geothermal Gradient ◽  
Creep Model ◽  
Salt Rock ◽  
Salt Creep ◽  
Rock Creep ◽  
Salt Caverns ◽  
Oil Tanks

Abstract The crude oil price has been keeping at a low level in recent years, which made China's government put more efforts in the development of underground oil storages in depleted salt caverns. Under the initiative of "the Belt and Road", a more concrete concept which is "the Silk Road Economic Belt and the 21st-Century Maritime Silk Road" successfully connects Jiangsu Province in the east of China. Consisting of 20 depleted caverns, Huai'an project that is still under planning is one of the most successful examples that turn depleted salt caverns into underground crude oil storages in China. Each cavern takes up 24×104m3, while the project totally takes up 480×104m3. TDMA algorithm was adopted to solve the heat exchange model of oil, brine and surrounding rocks, revealing the relationship between temperature and cavern pressure. Salt rock safety factor, salt cavern shrinkage ratio, axial stress and ground subsidence were taken into consideration to establish a 3-dimension salt rock creep model for 19 depleted salt caverns, so that the caverns’ shapes were optimized. Hydrodynamics models were used to determine the oil's flow rate into and out of a 1000m deep cavern whose thermal field was simulated by software to reveal the temperature limit of oil and brine. Due to geothermal gradient and continuous heat transmission, the average temperature of oil and brine goes up from 35°C to 44.3°C within 7 years, while the inner pressure goes up from 12.96MPa to 21.93MPa in a depleted salt cavern. Salt creep ratio decreases as oil is stored in underground caverns for a longer period. Salt is hardly penetrated by oil, while the temperature change has a strong influence on caverns’ internal pressure. The thermal expansion factor and compressibility coefficient of crude oil and brine are both crucial to the temperature's effect on internal pressure. Caverns that have larger segments in their upper-middle or middle parts are more stable and resistant to salt creep than those that have larger segments in their lower parts. When oil is injected or pumped out, it is necessary to make the internal pressure lower than the static pressure of surrounding rocks. Hence, the most appropriate flow rate of crude oil is 4.5m/s. Crude oil that is stored in deep salt caverns may be heated up to 60°C due to the geothermal gradient, but the flammable gas in oil is rapidly gasified or even explodes when it is pumped out to the surface. To avoid accidents and air pollution, oil is cooled down before being delivered via pipelines. Oil tanks used to be applied by scale in China, however they are too obvious on the ground to comply with national strategic energy safety. Compared with oil tanks of similar volumes, the Huai'an underground oil storages may save the overall cost by 35.3%. It is the first time that the salt rock creep model is established in depleted salt caverns, while the conclusion overthrew the common preference of regular cylindrical caverns.

scholarly journals Creep Behaviours of Argillaceous Sandstone: An Experimental and Modelling Study

2020 ◽  
Vol 10 (21) ◽  
pp. 7602
Author(s):  
Huaiguo Zheng ◽  
Qingxiang Cai ◽  
Wei Zhou ◽  
Xiang Lu ◽  
Ming Li ◽  
...  
Keyword(s):  
Experimental Investigation ◽  
Creep Model ◽  
Nonlinear Creep ◽  
Underground Excavations ◽  
Creep Theory ◽  
Term Stability ◽  
Long Term Stability ◽  
Rock Creep ◽  
Confining Pressures

Understanding the creep behaviours of rocks is essential for the long-term stability of underground excavations in mining engineering. Creep behaviours are more important when the mining depth is greater, which leads to the emergence of weak rock masses and high in situ stresses. In this study, the creep behaviours of argillaceous sandstone (AS) were systematically investigated. For the experimental investigation, creep tests were conducted on AS with different confining pressures (3, 6, 9, 12, 15, and 18 MPa) using an MTS815.02 rock mechanics test system. The mechanical characteristics of AS were analysed. For the numerical study, a nonlinear creep model of AS under equal and different confining pressures was established based on rock creep theory and plastic theory. The results showed that confining pressure could effectively improve the creep failure strength of AS, accelerating its creep deformation rate and process and reducing the final expansion volume. The nonlinear creep model was embedded in the FLAC3D software, and the experimental and numerical results agreed well. The experimental investigation and proposed creep model can provide important guidance in underground mines for safe long-term stability of underground excavations.

scholarly journals The 3D Nonstationary Creep Constitutive Model of Sandstone Based on Fractional Order

2019 ◽  
Vol 2019 ◽  
pp. 1-12
Author(s):  
Shuguang Zhang ◽  
Wenbo Liu
Keyword(s):  
Fractional Order ◽  
Creep Test ◽  
Creep Model ◽  
Good Prediction ◽  
Test Machine ◽  
Nonlinear Creep ◽  
Creep Characteristics ◽  
Marquardt Algorithm ◽  
Rock Creep ◽  
Triaxial Creep

Based on nonlinear creep characteristics of rock, triaxial creep tests were conducted on sandstone by using an MTS812.02 test machine. The creep properties of rocks under different conditions were analyzed. Establishing a creep model that describes parameter degradation is necessary to address the deterioration of rock creep parameters over time. A nonstationary Abel pot was constructed on the basis of laws of damage accumulation and deterioration. Then, the nonstationary creep model was established according to fractional order theory. The parameters of the triaxial creep test curve under different confining pressures were identified on the basis of Levenberg–Marquardt algorithm in Hengda coal mine in Fuxin, China. By comparing the model curve with the experimental curve, we found that the nonlinear model not only accurately reflected the creep characteristics of the decay and steady creep stages but also overcame the limitation of traditional creep model, that is, difficulty in describing the accelerated creep. Finally, the influence of fractional order and nonstationary parameters on rock creep was obtained by parameter sensitivity analysis. Overall, the model had high fitting degree as well as good prediction and analysis for 3D creep test data.

Probability Distribution Analysis of Rock Salt Creep Parameters Based on Comprehensive Optimal Acceptance Criteria

2013 ◽  
Vol 577-578 ◽  
pp. 561-564
Author(s):  
Ji Wei Ma ◽  
Zhi Yin Wang ◽  
Jin Peng Wu
Keyword(s):  
Probability Distribution ◽  
Probability Model ◽  
Model Fitting ◽  
Test Method ◽  
Creep Model ◽  
Distribution Analysis ◽  
Salt Rock ◽  
Acceptance Criteria ◽  
Salt Creep ◽  
Rock Creep

According to salt rock creep test data and strain variation regulation of a salt mine, salt rock creep parameters are obtained based on Burgers creep model fitting. Statistical study of the probability distribution of the salt rock Burgers model creep parameters is carried out by K-S, A-D and C-M test method, from which probability model for each creep parameters is obtained. To achieve the purpose of determining the optimal probability model for each creep parameters, considering the acceptable level of various test method to different hypothesis probability model, the author put forward the comprehensive optimal acceptance criteria on the basis of limited comparison method, the correctness of which is proved by test result.

scholarly journals A Time-Dependent Creep Constitutive Model of Deep Surrounding Rock under Temperature-Stress Coupling

2021 ◽  
Vol 2021 ◽  
pp. 1-11
Author(s):  
Xiaofeng Li ◽  
Zhixiang Yin
Keyword(s):  
Creep Deformation ◽  
Test System ◽  
Surrounding Rock ◽  
Creep Model ◽  
Spring Element ◽  
Rock Creep ◽  
Accelerated Creep ◽  
Different Temperatures ◽  
Creep Constitutive Model ◽  
Triaxial Creep Test

In order to study the creep behavior of the surrounding rock of Hengda coal mine in Fuxin under different temperatures, the triaxial creep test of sandstone is carried out by the MTS815.02 test system. The relationship between damage variables and temperature is constructed based on the Weibull distribution of the meso-probability voxel intensity. Aiming at the nonlinear characteristics of rock creep, a nonlinear viscous pot element and a nonlinear spring element are proposed. The two linear viscous pot elements and one linear spring element in the Nishihara model can be replaced separately. Thus, an unsteady parameter creep model is established. The comparison between the Nishihara model curve and the model and the experimental curves in this article has been added to the article. Furthermore, the superiority of this model can be proved. The results show that the established variable-time aging creep model not only can describe the rock attenuation creep and stable creep deformation characteristics but also can make up for the shortcomings of the traditional creep model that cannot describe the accelerated creep characteristics. Moreover, it predicts the development law of creep deformation well. The model is in good agreement with the test curve, which shows the correctness and rationality of the model. It has guiding significance for actual engineering support and prediction of long-term deformation of surrounding rock.

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