Evaluating Long‐Term Strength and Time to Failure of Sandstone with Different Initial Damage

Hou, Rongbin; Shi, Yanke; Xu, Lingyun; Fu, Jinwei; Zhang, Kai

doi:10.1155/2020/7149148

Cited by 5 publications

(6 citation statements)

References 24 publications

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“…Particularly, in deep-buried underground caverns and roadways, large deformations and rock-mass failures occur along with rock-mass unloading because of complicated external conditions. Terefore, the creep mechanical behavior of such rocks is closely related to the longterm stability of the engineering structure, which should be carefully studied in the design, operation, and maintenance of tunnels [4][5][6].…”

Section: Introductionmentioning

confidence: 99%

Modified Rheological Model for Deep‐Buried Silty Mudstone and Support Time Analysis Application

Zhou

et al. 2023

Mathematical Problems in Engineering

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The rheological properties of soft rocks should be considered in the long-term design and maintenance of deep-buried tunnels using uniaxial single-stage loading and graded incremental cyclic-loading methods. In this article, creep tests were performed on deep-buried silty mudstone from a specific water conveyance tunnel in China, with a buried depth in the range of 1650–2320 m and subjected to high in situ stress. The creep curves of silty mudstone under different loading stresses were obtained, showing evident rheological mechanical behavior under complicated external environmental conditions. Based on the classic Burgers rheological model, a new nonlinear creep model was established based on the creep properties of deep-buried silty mudstone in the project area. Typically, the designated rheological models for certain projects are unsuitable or inadequate. A nonlinear dashpot was calculated using the Levenberg–Marquardt (L–M) method coupled with origin to account for the deterioration trend in the strength of the silty mudstone over time. With the determined parameters, the modified Burgers model exhibited good qualitative consistency with field monitoring data. The user-defined material mechanical behavior (UMAT) subroutine of the modified Burgers model was successfully achieved after it was implemented in the numerical code ABAQUS. Based on the full-rheological effect, the proper supporting time of a deep-buried tunnel was studied, and it was proposed that a second lining should be cast in situ approximately 150 days after the excavation of the tunnel. The outcomes of the proposed modified rheological model can accurately represent the creep behavior of deep-buried silty mudstones in a specific engineering instance. The research results can provide a basis for the rheological behavior and supporting time of deep-buried silty mudstone.

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Section: Introductionmentioning

confidence: 99%

Modified Rheological Model for Deep‐Buried Silty Mudstone and Support Time Analysis Application

Zhou

et al. 2023

Mathematical Problems in Engineering

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“…Ding et al [16] comparatively analyzed and discussed the isochronous stress-strain curve method and the volume expansion method. Hou et al [17] determined the long-term strength of rock samples with differing initial damage by using four methods: the isochronous stress-strain curve, the steady-state creep method, the volume expansion method, and the steady-state creep rate intersection point method. Damjanac and Fairhurst [18] verified that the long-term strength of hard brittle rock was no less than 40% of the instantaneous strength, and they determined the long-term strength of rock through the relationship between the instantaneous strength and long-term strength.…”

Section: Introductionmentioning

confidence: 99%

Study on Creep Characteristics and Long-Term Strength of Mud-Calcareous Conglomerates in the Three Gorges Reservoir Area

et al. 2023

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The study of the time-dependent properties of engineering rock masses is a frontier topic in rock mechanics. In this study, creep tests and stress relaxation tests were conducted on mud-calcareous conglomerates from the Three Gorges Reservoir Area, and the long-term strength values of the conglomerate specimens were determined via different methods based on the test curves. By comparing these mainstream long-term strength determination methods, it was found that each of these methods have their own drawbacks. For example, the transition creep method requires a high accuracy of the test curve and only obtains an approximate strength interval rather than an accurate value. The long-term strength values determined by the isochronous stress–strain curve method are strongly influenced by subjective factors, among other things. Therefore, this paper proposes a new method for determining long-term strength, called the steady-state creep rate method, based on stress intervals. By comparison, the long-term strength values determined via this method are in good agreement with the transition creep method, the volume expansion method, and the stress relaxation method.

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“…Qiu et al used the ratio of the stress level loaded on a rock to the peak strength under the corresponding conditions of rock to characterize the predamaged degree [18]. Hou et al defined the predamaged degree based on the axial strain and elastic modulus and prepared samples with different initial damage degrees through a uniaxial preloading test [19]. Huang et al defined the predamaged degree of coal samples based on strain energy and prepared coal samples with different initial damage degrees by cyclic loading and unloading test [20].…”

Section: Introductionmentioning

confidence: 99%

Mechanical Behaviors and Damage Evolution Characteristics of Predamaged Rock under Triaxial Compression Experiment

Guo

Shang

Yuan

et al. 2022

Advances in Materials Science and Engineering

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The underground rock was disturbed repeatedly during the excavation, resulting in its damage degree gradually accumulated. Therefore, the rock in practical engineering can be regarded as predamaged (PD) rock, and its mechanical behaviors are different from conventional intact rock. This paper proposed the calibrate method to evaluate the predamaged degree of rock based on acoustic emission (AE) ring counts, and the PD rock samples were prepared by uniaxial cyclic loading and unloading test. Then, the triaxial compression experiment of predamaged rock was carried out to study the influence of different predamaged degrees on mechanical behaviors and damage evolution characteristics. The results show that the peak stress and axial strain of PD rock decrease gradually with the increase of predamaged degree. The yield stage of PD rock was significantly shorter than that of intact rock, and it entered the dilation deformation earlier. Furthermore, the constitutive equation of the PD rock based on energy was constructed and the damage evolution characteristics of PD rock were analyzed. It was observed that the bigger the predamaged degree was, the earlier the rock entered the damage, and the failure mode was more complex and crushed. The research results can provide the theoretical basis for the stability control of engineering disturbed rock.

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Evaluating Long‐Term Strength and Time to Failure of Sandstone with Different Initial Damage

Cited by 5 publications

References 24 publications

Modified Rheological Model for Deep‐Buried Silty Mudstone and Support Time Analysis Application

Modified Rheological Model for Deep‐Buried Silty Mudstone and Support Time Analysis Application

Study on Creep Characteristics and Long-Term Strength of Mud-Calcareous Conglomerates in the Three Gorges Reservoir Area

Mechanical Behaviors and Damage Evolution Characteristics of Predamaged Rock under Triaxial Compression Experiment

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