Energy Characteristics and Damage Constitutive Model of Frozen Sandstone under Triaxial Compression

2022 ◽  
Vol 36 (1) ◽  
Author(s):  
Shuai Liu ◽  
Gengshe Yang ◽  
Xihao Dong ◽  
Yanjun Shen ◽  
Hui Liu
Keyword(s):  
Constitutive Model ◽  
Triaxial Compression ◽  
Energy Characteristics ◽  
Damage Constitutive Model

scholarly journals A Thermal Damage Constitutive Model for Oil Shale Based on Weibull Statistical Theory

2019 ◽  
Vol 2019 ◽  
pp. 1-11 ◽  
Author(s):  
Guijie Zhao ◽  
Chen Chen ◽  
Huan Yan
Keyword(s):  
High Temperature ◽  
Constitutive Model ◽  
Oil Shale ◽  
Thermal Damage ◽  
Triaxial Compression ◽  
Strain Curve ◽  
Practical Significance ◽  
Compression Tests ◽  
Different Temperatures ◽  
Damage Constitutive Model

In this work, we first studied the thermal damage to typical rocks, assuming that the strength of thermally damaged rock microelements obeys a Weibull distribution and considering the influence of temperature on rock mechanical parameters; under the condition that microelement failure conforms to the Drucker–Prager criterion, the statistical thermal damage constitutive model of rocks after high-temperature exposure was established. On this basis, conventional triaxial compression tests were carried out on oil shale specimens heated to different temperatures, and according to the results of these tests, the relationship between the temperature and parameters in the statistical thermal damage constitutive model was determined, and the thermal damage constitutive model for oil shale was established. The results show that the thermal damage in oil shale increases with the increase of temperature; the damage variable is largest at 700°C, reaching 0.636; from room temperature to 700°C, the elastic modulus and Poisson’s ratio decrease by 62.66% and 64.57%, respectively; the theoretical stress-strain curve obtained from the model is in good agreement with the measured curves; the maximum difference between the two curves before peak strength is only 5 × 10−4; the model accurately reflects the deformation characteristics of oil shale at high temperature. The research results are of practical significance to the underground in situ thermal processing of oil shale.

scholarly journals Statistical Damage Constitutive Model for Cemented Sand considering the Residual Strength and Initial Compaction Phase

2018 ◽  
Vol 2018 ◽  
pp. 1-9 ◽  
Author(s):  
Cai Tan ◽  
Ming-dao Yuan ◽  
Yong-sheng Shi ◽  
Bing-sheng Zhou ◽  
Hao Li
Keyword(s):  
Constitutive Model ◽  
Residual Strength ◽  
Damage Mechanics ◽  
Triaxial Compression ◽  
Triaxial Stress ◽  
Cemented Sand ◽  
Damage Constitutive Model ◽  
Statistical Damage Constitutive Model ◽  
Initial Compaction ◽  
Statistical Damage

Based on continuum damage mechanics and the assumption of volume invariance, a damage constitutive model of cemented sand under triaxial stress was established while considering residual strength. Statistical theory was then introduced into this model. Assuming that the microunit strength of cemented sand obeys a Weibull random distribution, an expression of microunit strength based on the Mohr–Coulomb criterion was derived. Additionally, a damage evolution equation and a statistical damage constitutive model of cemented sand under triaxial stress were established. In order to consider the nonlinear deformation and volume change in the initial pore compaction stage, the critical point reflecting the completion of the initial compaction stage was determined. This was done by applying the volume invariance assumption to the linear portion of the stress and strain curve and performing a coordinate transformation. The nonlinearity of the initial compaction stage was fitted by a quadratic function. A triaxial compression test of cemented sand was then carried out to verify this proposed method. The results show that the calculated values by the damage constitutive model fit well with the actual experimental values and that the calculated results can reflect the stress softening, residual strength, and initial compaction characteristics of cemented sand, which shows the rationality and feasibility of the model.

scholarly journals Study of Damage Constitutive Model of Brittle Rocks considering Stress Dropping Characteristics

2020 ◽  
Vol 2020 ◽  
pp. 1-9
Author(s):  
Fei Li ◽  
Shuang You ◽  
Hongguang Ji ◽  
Hao Wang
Keyword(s):  
Constitutive Model ◽  
Triaxial Compression ◽  
Strain Curve ◽  
Brittle Rock ◽  
Model Parameters ◽  
Deformation And Failure ◽  
Brittle Rocks ◽  
Whole Process ◽  
Confining Pressures ◽  
Damage Constitutive Model

Deep brittle rock exhibits characteristics of rapid stress dropping rate and large stress dropping degree after peak failure. To simulate the whole process of deformation and failure of the deep brittle rock under load, the Lemaitre strain equivalent theory is modified to make the damaged part of the rock has residual stress. Based on the damage constitutive model considering residual strength characteristics, a correction factor reflecting stress dropping rate is added, the Weibull distribution is used to describe the inhomogeneity of rock materials, and Drucker–Prager criterion is used to quantitatively describe the influence of stress on damage; a damage constitutive model of deep brittle rock considering stress dropping characteristics is established. According to the geometric features of the rock stress-strain curve, the theoretical expressions of model parameters are derived. To verify the rationality of the model, triaxial compression experiments of deep brittle rock under different confining pressures are conducted. And the influence of model parameters on rock mechanical behaviour is analysed. The results show that the model reflects the stress dropping characteristics of deep brittle rock and the theoretical curve is in good agreement with the experimental results, which indicates that the proposed constitutive model is scientific and feasible.

Statistical damage model with strain softening and hardening for rocks under the influence of voids and volume changes

2010 ◽  
Vol 47 (8) ◽  
pp. 857-871 ◽  
Author(s):  
Wen-Gui Cao ◽  
Heng Zhao ◽  
Xiang Li ◽  
Yong-Jie Zhang
Keyword(s):  
Constitutive Model ◽  
Strain Softening ◽  
Triaxial Compression ◽  
Damage Model ◽  
Damage Threshold ◽  
Model Parameters ◽  
Volume Changes ◽  
Conventional Triaxial Compression ◽  
Damage Constitutive Model ◽  
Statistical Damage

With regards to the composition of natural rocks including voids or pores, deformation behavior is strongly affected by variation in porosity. By using a statistical damage-based approach, the characteristics of strain softening and hardening under the influence of voids and volume changes are investigated in the present paper. Suppose that a rock consists of three parts: voids, a damaged part, and an undamaged part. The effects of voids and volume changes on rock behavior are first analyzed through determination of the porosity and an associated damage model is then developed. Later, a statistical evolution equation describing the influence of the damage threshold on the propagation condition of rock damage is formulated based on measurement of the mesoscopic element strength. A statistical damage constitutive model reflecting strain softening and hardening behavior for rocks loaded in conventional triaxial compression is further developed and a corresponding method for determining the model parameters is also provided. Theoretical results of this proposed model are then compared with those observed experimentally. Finally, several aspects of the present constitutive model, which affect the relevant behavior of rocks, are particularly discussed.

scholarly journals Study on Damage Constitutive Model of High-Concentration Cemented Backfill in Coal Mine

Geofluids ◽  
2021 ◽  
Vol 2021 ◽  
pp. 1-12
Author(s):  
Baogui Yang ◽  
Haigang Yang
Keyword(s):  
Constitutive Model ◽  
Coal Mine ◽  
Damage Evolution ◽  
Triaxial Compression ◽  
Failure Process ◽  
Model Parameters ◽  
High Concentration ◽  
Deformation And Failure ◽  
Cemented Backfill ◽  
Damage Constitutive Model

In order to construct the damage constitutive model (DCM) of high-concentration cemented backfill (HCCB) in coal mine, the generalized Hoek-Brown strength criterion was used as the failure criterion. For the difference of theoretical derivation of constitutive relation, a new DCM based on residual strength was proposed. Combined with the conventional triaxial compression test, the correctness and rationality of the DCM were verified. The damage evolution characteristics of HCCB were analyzed, and the physical meaning of model parameters was clarified. The results show that (a) the theoretical curves of stress-strain relation are in good agreement with its experimental curves, which means DCM can simulate the deformation and failure process of HCCB. (b) The damage evolution curve of HCCB is S -shaped. To some extent, the confining pressure can inhibit the development of damage. (c) The parameter F 0 reflects the position of the peak point of the DCM, and parameter n is the slope of the straight line segment in the postpeak strain softening stage, which are, respectively, used to characterize the strength level and brittleness of HCCB. The establishment of DCM of HCCB is helpful to reveal its deformation and failure mechanism and provides theoretical basis for its strength design.

scholarly journals Study on Damage Constitutive Model of Rock under Freeze-Thaw-Confining Pressure-Acid Erosion

2021 ◽  
Vol 11 (20) ◽  
pp. 9431
Author(s):  
Youliang Chen ◽  
Peng Xiao ◽  
Xi Du ◽  
Suran Wang ◽  
Tomas Manuel Fernandez-Steeger ◽  
...  
Keyword(s):  
Constitutive Model ◽  
Damage Evolution ◽  
Damage Mechanics ◽  
Triaxial Compression ◽  
Confining Pressure ◽  
Model Parameters ◽  
Theoretical Derivation ◽  
Freeze Thaw ◽  
Peak Point ◽  
Damage Constitutive Model

Aiming at the acid-etched freeze-thaw rock for geotechnical engineering in cold regions, chemical damage variables, freeze-thaw damage variables, and force damage variables were introduced to define the degree of degradation of rock materials, the law of damage evolution, the total damage variable of acid-corroded rock under the coupling action of freeze-thaw and confining pressure was deduced. The continuous damage mechanics theory was adopted to derive the damage evolution equation and constitutive model of acid-eroded rock under the coupling action of freeze-thaw and confining pressure. The theoretical derivation method was used to obtain the required model parameter expressions. Finally, the model’s rationality and accuracy were verified by the triaxial compression test data of frozen-thawed rocks. Comparing the test curve’s peak point with the peak point of the model theoretical curve, the results show that the two are in suitable agreement. The damage constitutive model can better reflect the stress-strain peak characteristics of rock during triaxial compression, verifying the rationality and reliability of the model and the method for determining the model parameters. The model extends the damage model of rock under the coupling action of freeze-thaw and confining pressure in the chemical environment and further reveals the damage mechanism and failure law of acid-corroded rock under the coupling action of freeze-thaw and confining pressure.

scholarly journals Mechanical Characteristics of Red Sandstone Under Cyclic Wetting and Drying

2021 ◽  
Author(s):  
Zhao Baoyun ◽  
Li Yongfei ◽  
Huang Wei ◽  
Zhang Liyun ◽  
Li Wangcheng ◽  
...  
Keyword(s):  
Constitutive Model ◽  
Three Gorges Reservoir ◽  
Mechanical Characteristics ◽  
Triaxial Compression ◽  
Mechanical Parameters ◽  
Three Gorges ◽  
Compression Tests ◽  
Red Sandstone ◽  
The Three Gorges ◽  
Damage Constitutive Model

Abstract The bank slope of the Three Gorges Reservoir is affected by seasonal water level fluctuations, which leads to deterioration of the rock mass, resulting in a series of geological disasters such as landslides and mudslides. Therefore, in order to thoroughly understand the degradation mechanism of mechanical characteristics under wetting-drying cycles, uniaxial compression tests and triaxial compression tests were used to reveal the relationship between mechanical characteristics and wetting-drying cycles. Uniaxial compression tests results show that with the number of wetting-drying cycles increases, the mechanical characteristics show a decreasing trend, and the compaction stage of the sample increases significantly. It was found that the first 10 wetting-drying cycles have a greater impact on the mechanical characteristics of red sandstone under the triaxial compression condition, the mechanical parameters such as deviatoric stress, elasticity modulus dropped rapidly under the first 10 cycles and then tend to be stable. Based on the testing data under wetting-drying cycle condition, the mechanical parameters of the statistics damage constitutive model were modified and the results show that the modified damage constitutive model has a high degree of fit with the test data, indicating that the modified mechanical parameters can better reflect the degradation of red sandstone after the wetting-drying cycles. This understanding of the degradation process of the mechanical characteristics under wetting-drying cycles can provide theoretical guidance for the protection of dangerous slopes in the drawdown zone of the Three Gorges Reservoir.

Constitutive model of rock triaxial damage based on the rock strength statistics

2020 ◽  
Vol 29 (10) ◽  
pp. 1487-1511
Author(s):  
Kai Chen
Keyword(s):  
Constitutive Model ◽  
Rock Strength ◽  
Triaxial Compression ◽  
Confining Pressure ◽  
X Ray Diffraction ◽  
Proposed Model ◽  
Testing Data ◽  
Deformation Behaviors ◽  
Damage Constitutive Model ◽  
Rock Specimens

Firstly, an X-ray diffraction test is carried out to investigate brittle rock specimens’ composition, and a triaxial compression test is conducted to study the deformation behaviors and mechanical properties. Then, assuming that the rock material is able to be divided into the elastic part satisfying the Hooke’s law and the damage part where rock strength follows lognormal distribution, this paper determines a damage variable and establishes a damage constitutive model which effectively reflects the residual strength in the process of rock failure. Meanwhile, testing data are used to validate the reliability of the proposed model in this paper and the dependence of statistic parameters on the confining pressure. Finally, impacts caused by statistic parameters variation on compression strength are analyzed comprehensively, and we also conduct a comparison between this proposed model and other models from other literatures, thereby showing the reliability and rationality of this proposed model. In addition, the research outcomes presented in this paper also can effectively offer significant reference for the development of rock mechanics and rock engineering.

Sign in / Sign up

Export Citation Format

Share Document