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Experimental Investigation of the Mechanical Properties and Energy Evolution of Layered Phyllite Under Uniaxial Multilevel Cyclic Loading
Abstract To study the anisotropic mechanical properties and energy evolution of layered rock masses under the action of cyclic loading, uniaxial graded cyclic loading and unloading tests under different upper and lower stress limits were carried out on samples with different bedding angles (0°, 22.5°, 45°, 67.5°, and 90°) to explore the deformation and mechanical response characteristics of bedded phyllite under cyclic loading and the mechanism controlling the evolution of the total absorption energy, elastic strain energy, and dissipated energy. The damage variable D and the damage increment ΔD were introduced to characterize the damage accumulation state inside the layered rock mass, and an instability criterion of bedded phyllite under mechanical cyclic loading was proposed. The results show that when the bedding angle increases from 0° to 90°, the failure types of the sample change from splitting shear failure to slipping shear failure and then to splitting tensile failure, and the corresponding irreversible strain and deformation modulus first decrease and then increase. With increasing stress level, the cumulative energy density increases in three stages, and the rate of increase presents a change in characteristic of "accelerating-steady-decelerating." The energy storage coefficient (Ke) decreases with increasing cycle number and stress level and first increases and then decreases with increasing bedding angle. Meanwhile, the energy dissipation coefficient (Kd) exhibits the opposite trend. The damage increment increases ΔD sharply after the first cycle in the nonfailure stage, drops sharply in the next cycle, and gradually decreases and stabilizes to near ΔD = 0.01 in the subsequent cycle. After entering the failure stage, the change in the damage increment of the variation in phyllite samples with different bedding angles is closely related to the stress level and number of cycles. The damage variable D can be used to describe the failure and instability of bedded phyllite under graded cyclic loading: when D ≤ 2 × $ 10^{–4} $, the rock is in the stage of compaction and steady crack growth; when D ≥ 2 × $ 10^{–4} $, the rock is at risk of failure and instability.
Highlights The changes in the irreversible strain and elastic modulus were analyzed based on the results of uniaxial graded cyclic loading and unloading testing.The evolution and distribution rules of various energy indicators under uniaxial graded cycle load are discussed from the perspective of energy.An instability judgment index based on energy dissipation theory is proposed, considering the relationship of layered millennium rock macro–micro deformation and energy evolution under the cyclic load.
Experimental Investigation of the Mechanical Properties and Energy Evolution of Layered Phyllite Under Uniaxial Multilevel Cyclic Loading
Abstract To study the anisotropic mechanical properties and energy evolution of layered rock masses under the action of cyclic loading, uniaxial graded cyclic loading and unloading tests under different upper and lower stress limits were carried out on samples with different bedding angles (0°, 22.5°, 45°, 67.5°, and 90°) to explore the deformation and mechanical response characteristics of bedded phyllite under cyclic loading and the mechanism controlling the evolution of the total absorption energy, elastic strain energy, and dissipated energy. The damage variable D and the damage increment ΔD were introduced to characterize the damage accumulation state inside the layered rock mass, and an instability criterion of bedded phyllite under mechanical cyclic loading was proposed. The results show that when the bedding angle increases from 0° to 90°, the failure types of the sample change from splitting shear failure to slipping shear failure and then to splitting tensile failure, and the corresponding irreversible strain and deformation modulus first decrease and then increase. With increasing stress level, the cumulative energy density increases in three stages, and the rate of increase presents a change in characteristic of "accelerating-steady-decelerating." The energy storage coefficient (Ke) decreases with increasing cycle number and stress level and first increases and then decreases with increasing bedding angle. Meanwhile, the energy dissipation coefficient (Kd) exhibits the opposite trend. The damage increment increases ΔD sharply after the first cycle in the nonfailure stage, drops sharply in the next cycle, and gradually decreases and stabilizes to near ΔD = 0.01 in the subsequent cycle. After entering the failure stage, the change in the damage increment of the variation in phyllite samples with different bedding angles is closely related to the stress level and number of cycles. The damage variable D can be used to describe the failure and instability of bedded phyllite under graded cyclic loading: when D ≤ 2 × $ 10^{–4} $, the rock is in the stage of compaction and steady crack growth; when D ≥ 2 × $ 10^{–4} $, the rock is at risk of failure and instability.
Highlights The changes in the irreversible strain and elastic modulus were analyzed based on the results of uniaxial graded cyclic loading and unloading testing.The evolution and distribution rules of various energy indicators under uniaxial graded cycle load are discussed from the perspective of energy.An instability judgment index based on energy dissipation theory is proposed, considering the relationship of layered millennium rock macro–micro deformation and energy evolution under the cyclic load.
Experimental Investigation of the Mechanical Properties and Energy Evolution of Layered Phyllite Under Uniaxial Multilevel Cyclic Loading
Zhang, Jiabing (author) / Du, Ronghuan (author) / Chen, Yiling (author) / Huang, Zhen (author)
2023
Article (Journal)
Electronic Resource
English
BKL:
38.58
Geomechanik
/
56.20
Ingenieurgeologie, Bodenmechanik
/
38.58$jGeomechanik
/
56.20$jIngenieurgeologie$jBodenmechanik
RVK:
ELIB41
| British Library Online Contents | 2018