Energy Evolution and Acoustic Emission Characteristics of Sandstone Specimens under Unloading Confining Pressure

Qin, Tao; Duan, Yanwei; Sun, Hongru; Liu, Honglei; Wang, Lei

doi:10.1155/2019/1612576

Cited by 10 publications

(7 citation statements)

References 7 publications

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“…They found the change in elastic strain energy closely following the axial stress-strain curves and the dissipated energy increasing monotonically and acceleratively during loading. Similar phenomena were observed by other researchers on marbles [11,37], granites [38,39], dacites [40], and hard sandstones [41][42][43]. However, differences exist in the dissipated energy between different rocks.…”

Section: Introductionsupporting

confidence: 87%

Experimental Study on the Dilatancy and Energy Evolution Behaviors of Red-Bed Rocks under Unloading Conditions

Zheng,

Liu,

Zhuo

et al. 2023

Materials

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Surrounding rock deformation and consequent support failure are the most prominent issues in red-bed rock tunnel engineering and are mainly caused by the effects of unloading, rheology, and swelling. This study investigated the mechanical responses of two kinds of red-bed mudstone and sandstone under unloading conditions via laboratory observation. Volume dilation was observed on the rocks during unloading, and the dilatancy stress was linear with the initial confining pressure. However, the ratios of dilatancy stress to peak stress of the two rocks kept at a range from 0.8 to 0.9, regardless of confining pressures. Both the elastic strain energy and the dissipated energy evolved synchronously with the stress–strain curve and exhibited conspicuous confining pressure dependence. Special attention was paid to the evolution behavior of the dilatancy angle. The dilatancy angle changed linearly during unloading. When the confining pressure was 10 MPa, the dilatancy angle of mudstone decreased from 26.8° to 12.5° whereas the dilatancy angle of sandstone increased from 34.6° to 51.1°; when the confining pressure rose to 25 MPa, the dilatancy angle of mudstone and sandstone decreased from 45.8° to 17.4° and increased from 21.7° to 39.5°, respectively. To further understand the evolution of the dilatancy angle, we discussed the links between the variable dilatancy angle and the processes of rock deformation and energy dissipation.

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Section: Introductionsupporting

confidence: 87%

Experimental Study on the Dilatancy and Energy Evolution Behaviors of Red-Bed Rocks under Unloading Conditions

Zheng,

Liu,

Zhuo

et al. 2023

Materials

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“…Zhou et al studied the interaction of rock cracks under unloading conditions, which showed that the change of crack angle would weaken shear failure [6]. Qin et al studied the energy evolution and acoustic emission law of sandstone under unloading conditions [7]. It showed that, after the stress peak point of sandstone, the elastic strain energy would quickly be converted into dissipative energy, which leads to rock fracture.…”

Section: Introductionmentioning

confidence: 99%

Experimental Study on Triaxial Unloading Failure of Deep Composite Coal‐Rock

Yang

et al. 2021

Advances in Civil Engineering

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With the deep mining of coal, the phenomenon of high ground stress is more likely to cause dynamic disaster. In view of the above problems, this paper takes the unloading process of coal mining as the background to study the effects of mining rates under different conditions on the mechanical properties and triaxial failure criterion of composite coal-rock, so as to provide a theoretical basis for the prevention and control of dynamic disasters in coal mines. The composite coal-rock models with a composite ratio of 1 : 1 : 1 were tested under different unloading rates or confining pressures. The results show that the triaxial unloading process of coal-rock can be divided into five stages: compaction, single elasticity, elastic-plastic unloading, partial fracture, and complete fracture. In this paper, the failure criterion of composite coal-rock triaxial unloading is derived. The unloading rate has an exponential relationship with the triaxial compressive strength, and the relationship between initial confining pressure and compressive strength is linear. The triaxial compressive strength is determined by both. The peak strains ε of all samples under different unloading conditions were around 0.01. And initial confining pressure had an influence on the strain variation trend during the unloading of composite coal-rock. The higher the initial confining pressure, the greater the elastic modulus. In addition, an increase of initial confining pressure led to the increase of the total energy converted into dissipated part in the process of fracture and caused the obvious increase of the rebound characteristics of the curve. However, the unloading rate had no influence on the strain trend.

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“…According to the first law of thermodinamics, supposing the experiment system is a closed system ignoring the thermal energy dissipation in the experiment, the total energy U generated by the work done by external force is [23][24][25][26][27]…”

Section: Energy Calculation Methodsmentioning

confidence: 99%

Research on Stability Control Technology of Mining Roadway Based on Energy Transformation

2023

Self Cite

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The process of roadway surrounding rock deformation and instability is always accompanied by energy changes, and the energy transformation of surrounding rock directly drives its deformation and failure. In order to realize the stability control of mining roadway, the distribution of elastic strain energy and plastic strain energy of surrounding rock was analyzed by using FLAC3D numerical simulation software on the basis of the energy transformation law of sandstone under different confining pressures revealed by indoor triaxial compression test. Based on this, combined with the energy transformation, the principle of roadway surrounding rock stability control technology is proposed. One is to reduce the elastic strain energy of surrounding rock, that is, by increasing the extension of support body, part of the roadway energy is transferred to the support body, so as to improve the energy release of surrounding rock, or by optimizing the layout of roadway to reduce the energy accumulation of surrounding rock. The second is to increase the plastic strain energy of surrounding rock, that is, to increase the energy dissipation of surrounding rock by setting weak structure. The above research results are applied to the surrounding rock control of the right second transport roadway in the 91st coal of Xinjian coal mine. After the optimization of support measures, the roadway surface displacement and its increase rate decreased significantly, roof subsidence decreased from 247 mm to 62 mm, floor heave decreased from 120 mm to 26 mm, and the right rib shrinkage decreased from 292 mm to 94 mm, that is, the floor heave control effect was particularly obvious. The deformation of surrounding rock gradually stabilized after 45 days.

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Energy Evolution and Acoustic Emission Characteristics of Sandstone Specimens under Unloading Confining Pressure

Cited by 10 publications

References 7 publications

Experimental Study on the Dilatancy and Energy Evolution Behaviors of Red-Bed Rocks under Unloading Conditions

Experimental Study on the Dilatancy and Energy Evolution Behaviors of Red-Bed Rocks under Unloading Conditions

Experimental Study on Triaxial Unloading Failure of Deep Composite Coal‐Rock

Research on Stability Control Technology of Mining Roadway Based on Energy Transformation

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