Experimental analysis of dynamic and static mechanical properties of deep thick anhydrite cap rocks under high-stress conditions

Yin, Shuai; Xie, Rong‐Jun

doi:10.1007/s13146-018-0450-1

Cited by 8 publications

(4 citation statements)

References 28 publications

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“…We assume that the natural rock matrix frequency of oscillations 𝛺 is linked with the frequency of disturbing oscillations 𝜔 via some function 𝛺 𝛼𝜔 , where coefficient 𝛼 ≫ 1 means that the intrinsic matrix oscillation surpasses the external load oscillation. The coefficient 𝐵 is determined from (5); then (8) can be represented as The displacement of a mass u = u(t) from an equilibrium position specifies changes in a sample's length, which allows us to calculate l min and l max in (1). In accordance with Newton's second law, the Equation for mass is determined by the relation…”

Section: Model Formulationmentioning

confidence: 99%

“…The accuracy of geomechanical modelling, as well as the reliability of constructed geotechnical structures, depends on the values of elastic characteristics [4], the dynamic Young's modulus in particular, and phenomena laid out in the model. The most common technique for estimation of the dynamic Young's modulus of sedimentary rocks is the elastic wave theory, which is grounded in the principles of acoustic wave propagation through a porous rock [5][6][7][8][9][10][11][12][13][14][15]. According to such an approach, the dynamic Young's modulus is estimated using the velocity of waves, elastic constants, and rock density [16].…”

Section: Introductionmentioning

confidence: 99%

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Modelling of the Dynamic Young’s Modulus of a Sedimentary Rock Subjected to Nonstationary Loading

et al. 2020

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This paper presents a mathematical model that reflects the nature of the dynamic Young’s modulus of a dry sedimentary rock during nonstationary uniaxial loading. The model is based on an idealized model of a system suggested by Jaeger J.C. A rock sample is considered as a spring with stiffness, the bottom point of which is fixed, while the upper point carries a mass. A sample experiences dynamic load and the rock matrix response. Displacement of the mass from the equilibrium state sets the variation of the sample’s length. Displacement of all the sample’s points goes according to the same law regardless of the point location. The response of a rock to a disturbing nonstationary load is selected based on the combination of conditions of each experiment, such as the load frequency and amplitude and the mass, length, and diameter of a sample. The mathematical model is consistent with experimental data, according to which an increase in load frequency leads to an increase in the dynamic Young’s modulus for each value of the load. The accuracy of the models is evaluated. The relations underlying the model can be used as a basis to describe the Young’s modulus dispersion of sedimentary rocks under the influence of nonstationary loads.

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Section: Model Formulationmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Modelling of the Dynamic Young’s Modulus of a Sedimentary Rock Subjected to Nonstationary Loading

et al. 2020

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“…This is a simple geochemical system, and hydration is readily achievable under moderate laboratory conditions of temperature and pressure. Hydration of anhydrite under experimental differential stress conditions using natural polycrystalline rocks has been studied only recently (Li et al, 2019;Xu et al, 2019;Wang et al, 2020), with a focus on the mechanical properties of anhydrite (Yin and Xie 2019), and the expansion or swelling associated with hydration (Serafeimidis and Anagnostou, 2013;Xu et al, 2019;Li et al, 2019). Additionally, long term (several months long) hydration experiments, mainly on powders of sieved natural and synthetic anhydrite under hydrostatic conditions (water) have failed to produce hydration products or show relatively slow hydration rates (e.g., Ramsdell and Patridge, 1929;Leininger et al, 1957;Hardie, 1967).…”

Section: Introductionmentioning

confidence: 99%

Rapid hydration and weakening of anhydrite under stress: Implications for natural hydration in the Earth’s crust and mantle

Heeb

Healy

Timms

et al. 2023

Preprint

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Abstract. Mineral hydration is an important geological process that influences the rheology and geochemistry of rocks, and the fluid budget of the Earth’s crust and mantle. Steady-state differential compaction (SSDC), dry and ‘wet’ tests under confining pressure, and axial stress were conducted, for the first time, to investigate the influence of triaxial stress on hydration in anhydrite-gypsum aggregates. Characterization of the samples before and after triaxial experiments were performed with optical and scanning electron microscopy, including energy dispersive spectroscopy and electron backscatter diffraction mapping. Stress-strain data reveal that samples that underwent steady state differential compaction in the presence of fluids are ~14 to ~41 % weaker than samples deformed under ‘wet’ conditions. The microstructural analysis shows that there is a strong temporal and spatial connection between the geometry, distribution, and evolution of fractures and hydration products. The increasing reaction surface area in combination with pre-existing gypsum in a gypsum-bearing anhydrite rock led to rapid gypsification. The crystallographic orientations of newly formed vein-gypsum have a systematic preferred orientation for long distances along veins, beyond the grain boundaries of wall-rock anhydrite. Gypsum crystallographic orientations in {100} and {010} are systematically and preferentially aligned parallel to the direction of maximum shear stress (45° to σ1). Gypsum is also not always topotactically linked to the wall-rock anhydrite in the immediate vicinity. This study proposes that the selective inheritance of crystal orientations from favourably oriented wall-rock anhydrite grains for the minimization of free energy for nucleation under stress leads to the systematic preferred orientation of large new gypsum grains. A sequence is suggested for hydration under stress that requires the development of fractures accompanied by localised hydration. Hydration along fractures with a range of apertures up to 120 µm occurred in under 6 hours. Once formed, gypsum-filled veins represent weak surfaces and are the locations of further shear fracturing, brecciation, and eventual brittle failure. These findings imply that non-hydrostatic stress has a significant influence on hydration rates and subsequent mechanical strength of rocks. This phenomenon is applicable across a wide range of geological environments in Earth’s crust and upper mantle. Please find a graphical abstract in the PDF manuscript document and as PNG with the supplements.

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“…stability of engineering structures. Especially, due to a series of manmade and natural conditions during the construction and use of underground rock mass engineering, such as excavation disturbance, blasting construction and occurrence conditions of rock strata, the stability of surrounding rock is often affected by unsteady and complex stress environment, which leads to the complexity and uncertainty of deformation and failure characteristics (Yin and Xie, 2019;Ji and Guo, 2020;Lv et al, 2022;Yang et al, 2023). Therefore, it is of great engineering value and practical significance to study deformation and failure characteristics of rock under variable loading rates.…”

mentioning

confidence: 99%

Experimental study on mechanical and acoustic emission characteristics of sedimentary sandstone under different loading rates

Li,

Feng,

Yue

et al. 2023

Front. Earth Sci.

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In the field of rock engineering, complexity of stress environment is an important factor affecting its stability. Thus, in view of fracture mechanism of rock under different loading rates within the scope of quasi-static strain rate, four groups of uniaxial compression tests with different strain rates were carried out on sandstone specimens, and strength, deformation, failure modes and acoustic emission characteristics of specimens were compared and analyzed. Furthermore, the fracture mechanism was discussed from the perspective of fracture characteristics based on fractal dimension, crack propagation law inverted through acoustic emission b-value, and micro fracture morphology. The results showed that as the strain rate increased from 10 to 5 s−1 to 10−2 s−1, the fractal dimension of rock fragments increased, and the fractal dimension of rock fragments increased by 9.66%, 7.32%, and 3.77% successively for every 10 times increase in strain rate, which means that the equivalent size of fragments was getting smaller, and the fragmentation feature was becoming increasingly prominent. The crack propagation process based on acoustic emission b-value showed that with the increase of loading rate, the specimen entered the rapid crack propagation stage earlier, in order of 68%, 66%, 29%, and 22% of peak stress. Moreover, the microscopic fracture morphology showed that with the increase of loading rate, transgranular phenomenon was clear, and the fracture morphology changed from smooth to rough. That meant that the fracture of sandstone rock at high loading rates was mainly caused by the propagation of large cracks, which was different from the slow process of initiation, convergence and re-propagation of small cracks at low strain rates.

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Experimental analysis of dynamic and static mechanical properties of deep thick anhydrite cap rocks under high-stress conditions

Cited by 8 publications

References 28 publications

Modelling of the Dynamic Young’s Modulus of a Sedimentary Rock Subjected to Nonstationary Loading

Modelling of the Dynamic Young’s Modulus of a Sedimentary Rock Subjected to Nonstationary Loading

Rapid hydration and weakening of anhydrite under stress: Implications for natural hydration in the Earth’s crust and mantle

Experimental study on mechanical and acoustic emission characteristics of sedimentary sandstone under different loading rates

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