Strength and deformability of a low-porosity sandstone under true triaxial compression conditions

Zhang, Shihuai; Wu, Shunchuan; Zhang, Guang

doi:10.1016/j.ijrmms.2019.104204

Cited by 41 publications

(11 citation statements)

References 51 publications

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“…When confining pressure further increases, pure shear bands are predicted, in good accordance with experimental observations. 15 Finally, the sandstone is far from ductile regime under the experimental conditions. Compared with other porous sandstones, Zigong sandstone features a wide brittle range due to its low porosity.…”

Section: Effect Of Confining Pressure On Strain Localization Modementioning

confidence: 89%

“…Zigong sandstone represents a low-porosity (6.5%) hard sandstone composed mainly of silicate minerals, which has been systematically tested and investigated under different stress conditions. 8,14,15 Compared with other highly porous sandstones, Zigong sandstone features relatively higher strength and a wider brittle range. 15 It exhibits prominent characteristics of brittle fracturing even under a confining pressure (σ3) of as high as 80 MPa, approximately corresponding to a buried depth of 4 km.…”

Section: Experimental Materials and Experimental Proceduresmentioning

confidence: 99%

“…8,14,15 Compared with other highly porous sandstones, Zigong sandstone features relatively higher strength and a wider brittle range. 15 It exhibits prominent characteristics of brittle fracturing even under a confining pressure (σ3) of as high as 80 MPa, approximately corresponding to a buried depth of 4 km.…”

Section: Experimental Materials and Experimental Proceduresmentioning

confidence: 99%

“…In addition, the peak strength of Zigong sandstone can be well captured by Hoek-Brown failure criterion and its extended 3D version. 15,25…”

Section: Stress-strain Curves and Characteristic Stress Thresholdsmentioning

confidence: 99%

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Elastoplastic constitutive behavior and strain localization of a low-porosity sandstone during brittle fracturing

Zhang¹,

Guo²,

Wu³

2021

Preprint

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We investigated the elastoplastic behavior and strain localization of the Zigong sandstone (porosity: 6.5%) during brittle fracturing based on two series of axisymmetric compression experiments. The experiments were conducted under various confining pressures (σ3 = 0 ~ 80 MPa). For each confining pressure, the sandstone specimens were deformed under constant axial and circumferential strain rates, respectively. When σ3 < 60 MPa, the sandstone first undergoes stable deformation in the post-peak stage and then loses its stability. Before the emergence of instability, the mechanical behavior is hardly affected by the controlling method. When the confining is larger, the sandstone manifests a stable failure process during the whole loading stage. The observed elastoplastic behavior was described by a two-yield surface constitutive model established in the framework of generalized plastic mechanics. The proposed constitutive model incorporates two quadratic yield functions, as well as two linearly independent plastic potential functions, to honor the shear yield and volumetric dilatancy, respectively. Via the return mapping algorithm, the proposed constitutive model was verified by comparing the numerical results with experimental results. In addition, the two-yield surface constitutive model, which is equivalent to the model proposed by Rudnicki and Rice,1 was applied to localization analysis. Assuming that the onset of localization occurs at peak stress, frictional coefficient μ and dilatancy factor β were determined from experimental data. The variations of both plastic parameters predict the transition of localization mode from pure dilation bands under uniaxial compression to pure shear bands at high confining pressures, which is consistent with the experimental observations.

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Section: Effect Of Confining Pressure On Strain Localization Modementioning

confidence: 89%

Section: Experimental Materials and Experimental Proceduresmentioning

confidence: 99%

Section: Experimental Materials and Experimental Proceduresmentioning

confidence: 99%

“…In addition, the peak strength of Zigong sandstone can be well captured by Hoek-Brown failure criterion and its extended 3D version. 15,25…”

Section: Stress-strain Curves and Characteristic Stress Thresholdsmentioning

confidence: 99%

See 2 more Smart Citations

Elastoplastic constitutive behavior and strain localization of a low-porosity sandstone during brittle fracturing

Zhang¹,

Guo²,

Wu³

2021

Preprint

Self Cite

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“…The dependence of the compressibility coefficient of the pore volume on the value of the effective pressure has a pronounced non-linear character [25,26]. Therefore, it is important to know in what range of effective pressure changes the pore compressibility coefficient was estimated [27,28]. This prompted the authors to consider the available approaches to assessing compressibility in more details and choose from them the most accurate and adequately reflecting changes in the stress state of rocks that do not exceed their elastic and/or strength limit.…”

mentioning

confidence: 99%

Comparison of the approaches to assessing the compressibility of the pore space

Zhukov

Кузьмин

2022

PMI

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Integral and differential approaches to determining the volumetric compression of rocks caused by changes in the stress state are considered. Changes in the volume of the pore space of rocks are analyzed with an increase in its all-round compression. Estimation of changes in the compressibility coefficients of reservoirs due to the development of fields is an urgent problem, since the spread in the values of compressibility factors reduces the adequacy of estimates of changes in the physical properties and subsidence of the earth's surface of developed fields and underground gas storages. This parameter is key in assessing the geodynamic consequences of the long-term development of hydrocarbon deposits and the operation of underground gas storage facilities. Approaches to the assessment differ in the use of cumulative (integral) or local (differential) changes in porosity with a change in effective pressure. It is shown that the coefficient of volumetric compressibility of pores calculated by the integral approach significantly exceeds its value calculated by the differential approach, which is due to the accumulative nature of pore compression with an increase in effective pressure. It is shown that the differential approach more accurately determines the value of the pore compressibility coefficient, since it takes into account in more detail the features of the change in effective pressure.

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Triaxial Compression Testing at Constant and Reducing Confining Pressure for the Mechanical Characterization of a Specific Type of Sandstone

et al. 2021

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Strength and deformability of a low-porosity sandstone under true triaxial compression conditions

Cited by 41 publications

References 51 publications

Elastoplastic constitutive behavior and strain localization of a low-porosity sandstone during brittle fracturing

Elastoplastic constitutive behavior and strain localization of a low-porosity sandstone during brittle fracturing

Comparison of the approaches to assessing the compressibility of the pore space

Triaxial Compression Testing at Constant and Reducing Confining Pressure for the Mechanical Characterization of a Specific Type of Sandstone

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