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

ASME 2009 12th International Conference on Environmental Remediation and Radioactive Waste Management, Volume 1 ◽

10.1115/icem2009-16110 ◽

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.

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

Advances in Civil Engineering ◽

10.1155/2022/3063972 ◽

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.

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Study on long-term uniaxial compression creep mechanical behavior of rocksalt-mudstone combined body

International Journal of Damage Mechanics ◽

10.1177/10567895211035488 ◽

2021 ◽

pp. 105678952110354

Author(s):

Cheng Lyu ◽

Jianfeng Liu ◽

Yi Ren ◽

Chao Liang ◽

Qiangxing Zhang

Keyword(s):

Mechanical Behavior ◽

Constitutive Models ◽

Creep Damage ◽

Nonlinear Creep ◽

Creep Experiment ◽

Rock Creep ◽

Accelerated Creep ◽

Term Creep ◽

Bedded Rocks

Rocksalt and mudstone are usually under common stress in salt storage caverns, resulting in different mechanical properties from pure rocksalt and mudstone. To accurately obtain the creep mechanical characteristics of rocksalt-mudstone combined body, we have made three different combinations. The long-term creep experiment of bedded rocks can more closely reflect the long-term mechanical behavior of surrounding rock of salt storage caverns. The experimental results indicated that the long-term creep curve of the combined body includes initial and steady creep stages, and even includes accelerated creep stage. The strain of mudstone layer in the combined body was lower than that of rocksalt because of the higher strength. With the increase of the height ratio of mudstone, the creep strain of the combined body and each rock layer decreased, but the creep rate increased. A new nonlinear creep-damage constitutive model was proposed, which can well describe the creep evolution characteristics of the experiment. Compared with the fitting curves of classical Burgers and Nishihara creep constitutive models, it is revealed that the proposed model is most consistent with the experimental data. The duration of the long-term creep experiment under lower stress has a highly significant effect on the accuracy of predicting rock creep results. This research will contribute to a deeper understanding of the long-term creep characteristics of bedded rocks in salt storage caverns.

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ICONE15-10367 EVALUATION OF THE LONG-TERM MECHANICAL BEHAVIOR IN THE NEAR-FIELDS CONSIDERING CHEMICAL TRANSITIONS OF BARRIER MATERIALS

The Proceedings of the International Conference on Nuclear Engineering (ICONE) ◽

10.1299/jsmeicone.2007.15._icone1510_187 ◽

2007 ◽

Vol 2007.15 (0) ◽

pp. _ICONE1510-_ICONE1510

Author(s):

Fumihiro Sahara ◽

Takeshi Murakami ◽

Morihiro Mihara ◽

Takao Ohi

Keyword(s):

Mechanical Behavior ◽

Barrier Materials

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Creep Behaviours of Argillaceous Sandstone: An Experimental and Modelling Study

Applied Sciences ◽

10.3390/app10217602 ◽

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.

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Experimental and Analytical Study on Creep Characteristics of Box Section Bamboo-Steel Composite Columns under Long-Term Loading

Materials ◽

10.3390/ma14040983 ◽

2021 ◽

Vol 14 (4) ◽

pp. 983

Author(s):

Shixu Wu ◽

Keting Tong ◽

Jianmin Wang ◽

Yushun Li

Keyword(s):

Load Level ◽

Experimental Results ◽

Creep Model ◽

Composite Column ◽

Composite Columns ◽

Creep Coefficient ◽

Creep Characteristics ◽

Section Size ◽

Steel Composite

To expand the application of bamboo as a building material, a new type of box section composite column that combined bamboo and steel was considered in this paper. The creep characteristics of eight bamboo-steel composite columns with different parameters were tested to evaluate the effects of load level, section size and interface type under long-term loading. Then, the deformation development of the composite column under long-term loading was observed and analyzed. In addition, the creep-time relationship curve and the creep coefficient were created. Furthermore, the creep model of the composite column was proposed based on the relationship between the creep of the composite column and the creep of bamboo, and the calculated value of creep was compared with the experimental value. The experimental results showed that the creep development of the composite column was fast at first, and then became stable after about 90 days. The creep characteristics were mainly affected by long-term load level and section size. The creep coefficient was between 0.160 and 0.190. Moreover, the creep model proposed in this paper was applicable to predict the creep development of bamboo-steel composite columns. The calculation results were in good agreement with the experimental results.

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