scholarly journals Creep Properties and Constitutive Model of Salt Rock

2021 ◽  
Vol 2021 ◽  
pp. 1-29
Author(s):  
Qiang Zhang ◽  
Zhanping Song ◽  
Junbao Wang ◽  
Yuwei Zhang ◽  
Tong Wang
Keyword(s):  
Mechanical Properties ◽  
Constitutive Model ◽  
Effect Of Temperature ◽  
Creep Process ◽  
Underground Storage ◽  
Self Healing ◽  
Salt Rock ◽  
Creep Properties ◽  
Term Operation ◽  
Rock Creep

Due to the advantages of low porosity, low permeability, high ductility, and excellent capacities for creep and damage self-healing, salt rock is internationally considered as the ideal medium for underground storage of energy and disposal of radioactive waste. As one of the most important mechanical properties of salt rock, creep properties are closely related to the long-term operation stability and safety of salt rock underground storage cavern. A comprehensive review on the creep properties and constitutive model of salt rock is put forward in this paper. The opinions and suggestions on the research priority and direction of salt rock's mechanical properties in the future are put forward: (1) permeability variation of salt rock under the coupling effect of temperature and stress; (2) damage mechanism and evolution process under the effect of creep-fatigue interaction and low frequency cyclic loading; (3) microdeformation mechanisms of salt rock and the relationship between microstructure variations and macrocreep behavior during creep process; (4) the establishment of the creep damage constitutive model with simple form, less parameters, easy application, and considering the damage self-healing ability of salt rock simultaneously.

Investigating the Effect of Thermoelectric Processing on Ionic Aggregation in Thermoplastic Ionomers

2017 ◽  
Author(s):  
Prasant Vijayaraghavan ◽  
Vishnu-Baba Sundaresan
Keyword(s):  
Mechanical Properties ◽  
Electrostatic Field ◽  
Thermal Studies ◽  
Effect Of Temperature ◽  
Self Healing ◽  
Polymer Backbone ◽  
Ionic Dissociation ◽  
Dissociation Temperature ◽  
Aggregate Morphology ◽  
Poly Ethylene

Ionomers are a class of polymers which contain a small fraction of charged groups in the polymer backbone. These ionic groups aggregate (termed ionic aggregates) to form temporary cross-links that break apart over the ionic dissociation temperature and re-aggregate on cooling, influencing the mechanical properties of these polymers. In addition to enhanced mechanical properties, some ionomers also exhibit self-healing behavior. The self-healing behavior is a consequence of weakly bonded ionic aggregates breaking apart and re-aggregating after puncture or a ballistic impact. The structure and properties of ionomers have been studied over the last several decades; however, there is a lack of understanding of the influence of an electrostatic field on ionic aggregate morphology. Characterizing the effect of temperature and electric field on the formation and structure of these ionic aggregates will lead to preparation of ionomers with enhanced structural properties. This work focuses on Surlyn 8940 which a poly-ethylene methacryclic acid co-polymer in which a fraction of the carboxylic acid is terminated by sodium. In this work, Surlyn is thermoelectrically processed over its ionic dissociation temperature in the presence of a strong electrostatic field. Thermal studies are performed on the ionomer to study the effect of the thermoelectric processing. It is shown that the application of a thermoelectric field leads to increase in the ionic aggregate order in these materials and reduction in crystal size distribution. Thermal Analysis is performed using a Differential Scanning Calorimeter and the resulting thermogram analysis shows that thermoelectric processing increases the peak temperature and onset temperature of melting by 4 C and 20 C respectively. The peak width at half maximum of the melting endotherm is reduced by 10 C due to thermoelectric processing. This serves as a measure of the increased crystallinity. A parametric study on the effect of field duration and field strength is also performed.

scholarly journals Application of Multiphysics Coupling FEM on Open Wellbore Shrinkage and Casing Remaining Strength in an Incomplete Borehole in Deep Salt Formation

2015 ◽  
Vol 2015 ◽  
pp. 1-9 ◽  
Author(s):  
Hua Tong ◽  
Daqiang Guo ◽  
Xiaohua Zhu
Keyword(s):  
Three Dimensional ◽  
Effect Of Temperature ◽  
Salt Rock ◽  
Salt Formation ◽  
Defect Level ◽  
Rock Creep ◽  
Multiphysics Coupling ◽  
Casing Strength ◽  
New Perspective ◽  
Harsh Condition

Drilling and completing wells in deep salt stratum are technically challenging and costing, as when serving in an incomplete borehole in deep salt formation, well casing runs a high risk of collapse. To quantitatively calculate casing remaining strength under this harsh condition, a three-dimensional mechanical model is developed; then a computational model coupled with interbed salt rock-defective cement-casing and HPHT (high pressure and high temperature) is established and analyzed using multiphysics coupling FEM (finite element method); furthermore, open wellbore shrinkage and casing remaining strength under varying differential conditions in deep salt formation are discussed. The result demonstrates that the most serious shrinkage occurs at the middle of salt rock, and the combination action of salt rock creep, cement defect, and HPHT substantially lessens casing remaining strength; meanwhile, cement defect level should be taken into consideration when designing casing strength in deep salt formation, and apart from the consideration of temperature on casing the effect of temperature on cement properties also cannot be ignored. This study not only provides a theoretical basis for revealing the failure mechanism of well casing in deep complicated salt formation, but also acts as a new perspective of novel engineering applications of the multiphysics coupling FEM.

scholarly journals Experimental study on creep characteristics of infiltrated coal-rock under load

2021 ◽  
Author(s):  
Huimei Zhang ◽  
fuyu wang
Keyword(s):  
Mechanical Properties ◽  
Compressive Strength ◽  
Water Content ◽  
Uniaxial Compressive Strength ◽  
Stress Level ◽  
Water Infiltration ◽  
Creep Properties ◽  
Whole Process ◽  
Rock Creep ◽  
Coal Rock

Abstract For the water-rich zone in the coal tunnel rock body perennial suffer from water infiltration destabilization destruction problem.In this paper, the influence of stress level and infiltration time on the creep properties of coal-rock was systematically studied after the water infiltration test, scanning electron microscope(SEM), water content test, uniaxial compressive strength test and creep mechanical properties test.The whole process of coal-rock creep is described by Hooke's body, Kelvin body and damage elastic-plastic body, and the total damage variable was introduced to show the weakening effect of the coupling effect of stress and water infiltration on the creep properties of coal-rock.A creep constitutive model of coal rock damage considering the weakening effect of water infiltration was established, besides, the influence law of stress level and infiltration time on creep parameters of coal rock was analyzed.The study shows that coal rocks underwent a process from surface drying and shrinkage to water absorption and swelling to water-filled infiltration damage in the infiltration test.With the increase of infiltration time, the water content of coal-rock tended to increase and eventually stabilizes, while the uniaxial compressive strength gradually decreased.With the increase of stress level and infiltration time, the stable creep strain of coal-rock kept increasing which accelerated creep advance, and its internal damage continued to accumulate and eventually led to destabilization damage.At the same stress level, the creep parameter E0 showed a tendency to increase and then decreased with the increase of infiltration time, while E1, η1, tF, E2 and ν continued to decrease.Combined with the microstructural changes of coal rocks in the water infiltration process, the change law of mechanical properties of infiltrated coal-rock and the intrinsic softening mechanism were revealed.Comparing the theoretical model of infiltrated coal rock creep with the experimental data, the model developed in this paper reflected the whole process of infiltrated coal-rock creep deformation and damage, and can characterize the influence of infiltration time and stress level on coal-rock creep properties, which verified the reasonableness of the model.

Study on the Creep Parameters of Salt Rock Constitutive Function

2014 ◽  
Vol 1079-1080 ◽  
pp. 166-169 ◽  
Author(s):  
Hai Peng Zhang ◽  
Yi Jin ◽  
Long Ma
Keyword(s):  
Constitutive Model ◽  
Creep Test ◽  
Constitutive Equations ◽  
Determination Method ◽  
Salt Rock ◽  
Constitutive Function ◽  
Rock Creep ◽  
Creep Models ◽  
Creep Constitutive Model

Salt rock is a kind ofthe most suitablemedium for energy storages, because of its strongcreep behavior. "Burgers" and "Norton" is the two classic creep models. This paper starts from the establishment of creep constitutive model to obtain the determination method of creep constitutive parameters.Finally, it takes Nanjing salt rock creep test (2003) as an example to solve the parameters in Burgers and Norton constitutive equations.

Numerical Analysis for Thermal-Chemical-Stress Coupling in Deep Rock Creep Properties

2013 ◽  
Vol 561 ◽  
pp. 657-662
Author(s):  
Yan Chun Wang ◽  
Yuan Li ◽  
Jian Guang Li
Keyword(s):  
Ph Value ◽  
Coupling Effect ◽  
High Stress ◽  
Soft Rock ◽  
Effect Of Temperature ◽  
Creep Equation ◽  
Creep Properties ◽  
Rock Creep ◽  
Deep Rock ◽  
Rock Tunnel

The control equations for analyzing coupled thermal chemical-mechanical phenomena of deep rocks are established. Using creep equation by experimental data, 3D numerical simulation for creep properties of deep soft tunnel under coupling effect of temperature field, chemical field and stress field are conducted by ANSYS, and different effects of these fields on deep soft rock tunnel creep properties are analyzed, whats more time-creep curves of different temperature, pH value and stress deviation of the mid-point of the top of tunnel are obtained. Effect of these three fields on creep characteristics of deep soft rock cant be ignored. Under deep complex environment, high-stress is main factor of tunnel creep; creep increasing with temperature increasing. From simulation results, we get whether acidic environment or alkaline environment causes significantly stronger corrosive effect on the rock mass than the neutral environment, and increases its creep.

scholarly journals The effect of temperature on the mechanical properties and workability of rock salt

2019 ◽  
Vol 2 (1) ◽  
pp. 384-393
Author(s):  
Piotr Małkowski ◽  
Łukasz Bednarek ◽  
Krzysztof Kotwica ◽  
Grzegorz Stopka
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
Shear Strength ◽  
Temperature Increase ◽  
Laboratory Tests ◽  
Effect Of Temperature ◽  
Transverse Strain ◽  
Salt Rock ◽  
The Road ◽  
Salt Mining

Abstract Underground salt mining accounts for about 16 percent of the total salt production worldwide. When excavating salt rock, the cutters of the road header come into contact with the rock. This produces friction and, consequently, a rise in temperature. Generally, as temperature increases, salt gradually loses its plasticity. The extent of these alterations depends on the presence of other minerals in the rock. This paper presents the results of laboratory tests on regularly shaped samples of salt. An analysis was performed of the results of compressive, tensile and induced-shear strength, and of Young's modulus, Poisson's ratio, cuttability index and side chipping angle. The testing was conducted on samples with a temperature of about 20°C and samples heated to 50°C and 80°C. The tests showed that as temperature increased, so did compressive and tensile strength, and longitudinal and transverse strain of salt. The temperature increase caused, however, a decrease in shear strength. The cuttability index and the side chipping angle also decreased when the heated samples were being cut. The percentage changes in the parameters within the 60-degree temperature range were as high as several dozen percent.

scholarly journals Study on the Tri-axial Time-Dependent Deformation and Constitutive Model of Glauberite Salt Rock under the Coupled Effects of Compression and Dissolution

Energies ◽  
2020 ◽  
Vol 13 (7) ◽  
pp. 1797
Author(s):  
Mengtao Cao ◽  
Shunde Yin
Keyword(s):  
Mechanical Properties ◽  
Constitutive Model ◽  
Ct Scan ◽  
Time Dependent ◽  
Solid Skeleton ◽  
Micro Ct ◽  
Salt Rock ◽  
Hydraulic Connection ◽  
Infiltration Pressure ◽  
Damage Constitutive Model

Solution mining for glauberite salt rock is a long-term process that takes several years to several decades. Therefore, deposit deformations and subsidence of ground surfaces are time-dependent deformation problems that should consider the effect of water dissolution. In order to investigate the time-dependent deformation characteristics of glauberite salt rock, tri-axial time-dependent deformation tests were conducted under the condition of 4 MPa confining pressure and 5 MPa axial pressure with infiltration pressures of 3, 2, 1, and 0 MPa, respectively, and the micro-CT scan system was used to scan the glauberite specimens before and after the experiment in order to study the fracture evolution inside the specimen, and a damage constitutive model was established to fit the time-dependent deformation curves based on the damage mechanics and effective stress principle. To simulate the solution mining process, the time-dependent deformation process of glauberite salt rock was divided into three stages: hydraulic connection stage, water-saturated stage, and drainage stage. The results demonstrate that the hydraulic connection time for glauberite salt rock decreases with increasing infiltration pressure. The time-dependent deformations of the specimens at the hydraulic connection and saturated-water stages are significantly affected by the effective stress and continual mineral dissolution. At the drainage stage, the softening degree of the solid skeleton mechanical properties, which is caused by the dissolution effect and infiltration pressure loading history, decides the deformation of glauberite salt rock. In addition, the degree of softening inside glauberite salt rock caused by dissolution becomes more severe with increasing infiltration pressure using the micro-CT scan technology. Lastly, the time-dependent damage constitutive model is able to describe the tri-axial time-dependent deformation behavior of glauberite salt rock, and the variations of time-dependent deformation parameters further indicate the damage evolution of the solid skeleton mechanical properties of glauberite caused by infiltration pressure and dissolution effect.

scholarly journals A non-linear creep constitutive model for salt rock based on fractional derivatives

2019 ◽  
Vol 23 (Suppl. 3) ◽  
pp. 773-779 ◽  
Author(s):  
Jie Chen ◽  
Dan Lu ◽  
Fei Wu ◽  
Jinyang Fan ◽  
Wei Liu
Keyword(s):  
Constitutive Model ◽  
Creep Property ◽  
Salt Rock ◽  
Whole Process ◽  
Rock Creep ◽  
Non Linear ◽  
Accelerated Creep ◽  
Deep Underground ◽  
Abel Dashpot ◽  
Creep Constitutive Model

The creep property of the salt rock is an important determinant of deep underground repository of energy storage for long-term operatio. Starting from fractional derivative, this paper proposes a new concept of super Abel dashpot based on Abel dashpot. According to the Nishihara model, the non-linear element of super Abel dashpot is introduced, and a new salt rock creep constitutive model is established. The theoretical analytic solution of this model is then deduced. Fitting analysis of the experimental data indicates that the model can well reflect the whole-process creep curve, especially the non-linear accelerated creep stage.

scholarly journals Stability Analysis on the Long-Term Operation of the Horizontal Salt Rock Underground Storage

2021 ◽  
Vol 2021 ◽  
pp. 1-13
Author(s):  
Chengzhong Zhang ◽  
Qiang Zhang ◽  
Weiwei Li ◽  
Zhanping Song ◽  
Junbao Wang
Keyword(s):  
Underground Storage ◽  
Salt Rock ◽  
Height Ratio ◽  
Design Capacity ◽  
Term Operation ◽  
Operation Process ◽  
The Stability ◽  
Rock Deposit ◽  
Optimal Diameter

The construction of the vertical cavern in the salt dome deposit can meet the requirements of both storage capacity and tightness. However, if the vertical cavern is still used as the design shape of the salt rock underground storage in the layered salt rock deposit, the high design capacity cannot be guaranteed while the tightness is satisfied. In this case, the use of a large-span horizontal cavern as the design shape of the salt rock storage can not only effectively increase the design capacity of the storage, but also solve the problems such as the stability and tightness of the storage during the operation period by improving the structural form and working mode. Based on this, the ellipsoid-shaped horizontal salt rock underground storage is taken as an example, and a single-cavern horizontal salt rock underground storage model with different diameter-to-height ratios is established by using FLAC3D software. The change law of vertical and horizontal displacements, volume loss rate, and plastic zone distribution of salt rock storage changing with the diameter-to-height ratio are studied, and the optimal diameter-to-height ratio is determined. And then the long-term operation process of the double-cavern horizontal salt rock underground storage under the optimal diameter-to-height ratio is simulated, and the optimal pillar width is obtained.

scholarly journals Modified Nishihara Rheological Model considering the Effect of Thermal-Mechanical Coupling and Its Experimental Verification

2018 ◽  
Vol 2018 ◽  
pp. 1-9 ◽  
Author(s):  
Xingang Wang ◽  
Qiangbing Huang ◽  
Baoqin Lian ◽  
Nina Liu ◽  
Jun Zhang
Keyword(s):  
Rheological Model ◽  
Thermal Damage ◽  
Effect Of Temperature ◽  
Creep Process ◽  
Theoretical Formula ◽  
Mechanical Coupling ◽  
Good Ability ◽  
Rock Creep ◽  
Creep Models ◽  
Improved Model

The effect of temperature and pressure, which play important roles in the mechanical properties of rocks during deep energy exploitation, has not been sufficiently studied in the previous rock creep models. In order to investigate thermal effect in creep models, a modified Nishihara rheological model, taking into account the coupled effect of thermal damage and stress, was proposed by combining the theoretical formula for thermal damage of rocks with the modified Nishihara model. The improved model introduces a nonlinear viscous dashpot, which can accurately describe the accelerated rheological phase of rocks. To verify the proposed model, a triaxial rheological experiment was conducted on sandstone subjected to thermal damage (600°C). In addition, the stress-strain curves within whole creep process of the rheological experiment were analyzed. Furthermore, the theoretical curves of the modified Nishihara rheological model were compared with the experimental results. Results showed that the theoretical curves relatively agree well with the experimental data, suggesting that the proposed new model is more preferred to describing the rheological curve of sandstone subjected to thermal damage at different rheological stages, in particular, it is capable of depicting the accelerated rheological stage of the sandstone, providing a good ability to describe the creep behavior of rocks under thermal-mechanical coupling.

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