Experiment and Study on Mechanical Property of Sandstone Post-peak Under the Cyclic Loading and Unloading

Yang, Dafang; Zhang, Dingyuan; Niu, Shuangjian; Dang, Yuanheng; Feng, Wenlin; Ge, Shuangshuang

doi:10.1007/s10706-017-0414-6

Cited by 21 publications

(8 citation statements)

References 17 publications

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“…In the post-peak phase of the stress-strain curve, the strain usually has a significant increase when the stress changes little but has a downward trend, and it is generally considered that this is caused by the shear slip of the weak surface in the rock [74][75][76]. Therefore, this part of the strain is called shear-slip strain and can be used to characterize the plastic characteristics of the rock [36].…”

Section: Shear-slip Strainmentioning

confidence: 99%

Mineral Composition, Pore Structure, and Mechanical Characteristics of Pyroxene Granite Exposed to Heat Treatments

et al. 2019

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In deep geoengineering, including geothermal development, deep mining, and nuclear waste geological disposal, high temperature significantly affects the mineral properties of rocks, thereby changing their porous and mechanical characteristics. This paper experimentally studied the changes in mineral composition, pore structure, and mechanical characteristics of pyroxene granite heated to high temperature (from 25 °C to 1200 °C). The results concluded that (1) the high-temperature effect can be roughly identified as three stages: 25–500 °C, 500–800 °C, 800–1200 °C. (2) Below 500 °C, the maximum diffracted intensities of the essential minerals are comparatively stable and the porous and mechanical characteristics of granite samples change slightly, mainly due to mineral dehydration and uncoordinated thermal expansion; additionally, the failure mechanism of granite is brittle. (3) In 500–800 °C, the diffraction angles of the minerals become wider, pyroxene and quartz undergo phase transitions, and the difference in thermal expansion among minerals reaches a peak; the rock porosity increases rapidly by 1.95 times, and the newly created pores caused by high heat treatment are mainly medium ones with radii between 1 μm and 10 μm; the P-wave velocity and the elastic modulus decrease by 62.5% and 34.6%, respectively, and the peak strain increases greatly by 105.7%, indicating the failure mode changes from brittle to quasi-brittle. (4) In 800–1200 °C, illite and quartz react chemically to produce mullite and the crystal state of the minerals deteriorate dramatically; the porous and mechanical parameters of granite samples all change significantly and the P-wave, the uniaxial compressive strength (UCS), and the elastic modulus decrease by 81.30%, 81.20%, and 92.52%, while the rock porosity and the shear-slip strain increase by 4.10 times and 11.37 times, respectively; the failure mechanism of granite samples transforms from quasi-brittle to plastic, which also was confirmed with scanning electron microscopy (SEM).

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Section: Shear-slip Strainmentioning

confidence: 99%

Mineral Composition, Pore Structure, and Mechanical Characteristics of Pyroxene Granite Exposed to Heat Treatments

et al. 2019

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“…All of the test specimens were cylindrical, i.e., 50 mm in diameter and 100 mm in length. The specimens were soaked in distilled water for more than 72 h to ensure that they were fully saturated, which can reduce the post-peak brittleness of sandstone and guarantee post-peak unloading effects [25,26].…”

Section: Red Sandstonementioning

confidence: 99%

Experimental Investigation on the Post-Peak Short-Term and Creep Behavior of Fractured Sandstone

et al. 2020

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Short-term and creep tests of fractured sandstone with different degrees of damage prepared using pre-peak and post-peak unloading tests on intact sandstone were carried out using a servo-controlled rock mechanics system. Based on our experimental results, the influence of confining pressure and damage on short-term mechanical behavior of fractured sandstone with different degrees of damage was first analyzed. The results show that the peak strength, residual strength, elastic modulus, and secant modulus of fractured sandstone increase linearly with increasing confining pressure, but decrease with increasing damage. The short-term failure modes depend on the damage and change from typical shear failure modes to multiple shear failure modes with increasing damage. Then, the influence of the differential stress, confining pressure, and the degree of damage on the creep mechanical behavior of fractured specimens was further investigated. The axial instantaneous strain and creep strain increase linearly with increasing differential stress, and the specimens exhibit significant time-dependent behavior under high stress. The steady creep rate increases with increasing stress, but it decreases with increasing confining pressure and damage. However, the long-term strength and creep failure strength of fractured specimens increase linearly with increasing confining pressure, but they decrease linearly with increasing damage. The creep failure modes of fractured specimens are also the main shear failure modes, which are similar to the short-term failure modes.

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“…Some scholars have conducted experiments on rocks under cyclic loading. Yang et al [18] studied the mechanical property of sandstone post-peak under the cyclic loading and unloading; Zhang et al [20] carried out the lab tests on damage characteristics of sandstone subjected to pre-peak and postpeak cyclic loading; Munoz and Taheri [14] analyzed the post-peak deformability parameters of rocks under cyclic loading. ese studies can provide good experimental ideas and schemes for reference.…”

Section: Introductionmentioning

confidence: 99%

Experimental Study on Initial Damage Point of Deep Granite under Step Cyclic Loading Method

Guo

2021

Advances in Civil Engineering

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In deep engineering, the initial damage point of host rock has become an important concern. Nowadays, there are many methods which can work out the initial damage point. However, each existing method introduces some significant subjective or parametric errors. In this paper, a new determination method of initial damage point employing step cyclic loading tests was designed and a series of tests were conducted on deep granite. After analyzing the peak strength and effect of cyclic loading, the turning point of initial damage was confirmed. The testing results show that the turning stress of initial damage was about 45% peak strength and will present a little decrease with the confining pressure increasing. These calculated damage points are much more scientific, accurate, and intuitive, which provides a new method for the study on rock mechanics in deep mining.

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Experiment and Study on Mechanical Property of Sandstone Post-peak Under the Cyclic Loading and Unloading

Cited by 21 publications

References 17 publications

Mineral Composition, Pore Structure, and Mechanical Characteristics of Pyroxene Granite Exposed to Heat Treatments

Mineral Composition, Pore Structure, and Mechanical Characteristics of Pyroxene Granite Exposed to Heat Treatments

Experimental Investigation on the Post-Peak Short-Term and Creep Behavior of Fractured Sandstone

Experimental Study on Initial Damage Point of Deep Granite under Step Cyclic Loading Method

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