Superbrittleness of rocks at high confining pressure

Тарасов, Б. Г.

doi:10.36487/acg_repo/1074_08

Cited by 22 publications

(25 citation statements)

References 38 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The ratio of the elastic energy stored in the rock compression process to the elastic energy under ideal conditions is used to characterize the prepeak brittleness, and the higher ratio indicates the stronger brittleness. Thus, by obtaining the corresponding area of the stress–strain curve, we have − …”

Section: Results and Discussionmentioning

confidence: 99%

Shale Brittleness Index Based on the Energy Evolution Theory and Evaluation with Logging Data: A Case Study of the Guandong Block

Zhou²,

Li³

et al. 2020

ACS Omega

View full text Add to dashboard Cite

Shale brittleness is a key index that indicates the shale fracability, provides a basis for selecting wells and intervals to be fractured, and guarantees the good fracturing effect. The available models are not accurate in evaluating the shale brittleness when considering the confining pressure, and it is necessary to establish a new shale brittleness model under the geo-stress. In this study, the variation of elastic energy, fracture energy, and residual elastic energy in the whole process of rock compression and failure is analyzed based on the stress–strain curve in the experiments, and a shale brittleness index reflecting the energy evolution characteristics during rock failure under different confining pressures is established; a method of directly evaluating the shale brittleness with logging data by combining the rock mechanic experiment results with logging interpretation results is proposed. The calculation results show that the brittleness decreases as the confining pressure increases. When the confining pressure of the Kong-2 member shale of the Guandong block is less than 25 MPa, the brittleness index decreases significantly as the confining pressure increases, and when the confining pressure is greater than 25 MPa, the brittleness index decreases slightly. It is shown that the shale brittleness index is more sensitive to the confining pressure within a certain range and less sensitive to the confining pressure above a certain value.

show abstract

Section: Results and Discussionmentioning

confidence: 99%

Shale Brittleness Index Based on the Energy Evolution Theory and Evaluation with Logging Data: A Case Study of the Guandong Block

Zhou²,

Li³

et al. 2020

ACS Omega

View full text Add to dashboard Cite

show abstract

“…Indeed, it is difficult to explain the entire combination of the features of this phenomenon on the basis of the traditional understanding of rock failure mechanisms. This section demonstrates that all these features of shear rupture rockbursts represent manifestations of the intrinsic properties of the fan mechanism (Tarasov, 2010, 2014b, 2018).…”

Section: The Fan Mechanism As a Generator Of Induced Earthquakesmentioning

confidence: 88%

“…Experiments were conducted on dolerite specimens ( S uc ≈ 300 MPa) obtained from a seismically active gold mine in Australia (Tarasov, 2010; Tarasov & Randolph, 2008). The grain size ranged from 0.05 to 0.7 mm.…”

Section: New Approach To the Experimental Study Of Postpeak Propertie...mentioning

confidence: 99%

“…Since extraordinary features of the fan mechanism and the properties of rocks determined by it are contradictory to the modern ideas, the fan‐hinged approach is viewed with great skepticism and distrust. The problem is that in the brief papers published so far, it was impossible to present this extremely complex and extensive topic with clear arguments, reliable evidence, and detailed discussion (Tarasov, 2008, 2010, 2011, 2013, 2014, 2016, 2017, 2019; Tarasov & Guzev, 2013; Tarasov & Ortlepp, 2007; Tarasov & Potvin, 2013; Tarasov & Randolph, 2008, 2011, 2016; Tarasov & Sadovskii, 2016; Tarasov et al, 2016, 2017).…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Fan‐hinged shear instead of frictional stick–slip as the main and most dangerous mechanism of natural, induced, and volcanic earthquakes in the earth's crust

Tarasov

2023

Deep Underground Science and Engineering

View full text Add to dashboard Cite

Frictional stick–slip instability along pre‐existing faults has been accepted as the main mechanism of earthquakes for about 60 years, since it is believed that fracture of intact rocks cannot reflect such features inherent in earthquakes as low shear stresses activating instability, low stress drop, repetitive dynamic instability, and connection with pre‐existing faults. This paper demonstrates that all these features can be induced by a recently discovered shear rupture mechanism (fan‐hinged), which creates dynamic ruptures in intact rocks under stress conditions corresponding to seismogenic depths. The key element of this mechanism is the fan‐shaped structure of the head of extreme ruptures, which is formed as a result of an intense tensile cracking process, with the creation of inter‐crack slabs that act as hinges between the shearing rupture faces. The preference of the fan mechanism over the stick–slip mechanism is clear due to the extraordinary properties of the fan structure, which include the ability to generate new faults in intact dry rocks even at shear stresses that are an order of magnitude lower than the frictional strength; to provide shear resistance close to zero and abnormally large energy release; to cause a low stress drop; to use a new physics of energy supply to the rupture tip, providing supersonic rupture velocity; and to provide a previously unknown interrelation between earthquakes and volcanoes. All these properties make the fan mechanism the most dangerous rupture mechanism at the seismogenic depths of the earth's crust, generating the vast majority of earthquakes. The detailed analysis of the fan mechanism is presented in the companion paper “New physics of supersonic ruptures” published in DUSE. Further study of this subject is a major challenge for deep underground science, earthquake and fracture mechanics, volcanoes, physics, and tribology.

show abstract

“…Accepting this fact, the models were simplified by presenting the future fault as consisting of "predetermined" slabs. A detailed description of the physical and mathematical models is presented in previous papers (Tarasov, 2010(Tarasov, , 2014(Tarasov, , 2017(Tarasov, , 2019Tarasov & Guzev, 2013;Tarasov & Randolph, 2011Tarasov et al, 2017). This paper uses The structure of the future fault consists of a row of "predetermined" slabs (tiles) inclined at an angle α 0 to the rupture plane.…”

Section: Physical and Mathematical Models Of The Fan Mechanismmentioning

confidence: 99%

New physics of supersonic ruptures

Tarasov

2023

Deep Underground Science and Engineering

View full text Add to dashboard Cite

Until recently, it is believed that the rupture speed above the pressure wave is impossible since spontaneously propagating ruptures are driven by the energy released due to the rupture motion, which is transferred through the medium to the rupture tip region at the maximum speed equal to the pressure wave speed. However, the apparent violation of classic theories has been revealed by new experimental results demonstrating supersonic shear ruptures. This paper presents a detailed analysis of the recently discovered shear rupture mechanism (fan hinged), which suggests a new physics of energy supply to the tip of supersonic ruptures. The key element of this mechanism is the fan‐shaped structure of the head of extreme ruptures, which is formed as a result of an intense tensile cracking process with the creation of intercrack slabs that act as hinges between the shearing rupture faces. The fan structure is featured with the following extraordinary properties: extremely low friction approaching zero; amplification of shear stresses above the material strength at low applied shear stresses; creation of a self‐disbalancing stress state causing a spontaneous rupture growth; abnormally high energy release; generation of driving energy directly at the rupture tip which excludes the need to transfer energy through the medium. The fan mechanism operates in intact rocks at stress conditions corresponding to seismogenic depths and in pre‐existing extremely smooth interfaces due to identical tensile cracking processes at these conditions. This is Paper 1 (of two companion papers) which discusses the fan theory and extreme ruptures in experiments on extremely smooth interfaces. Paper 2 entitled “Fan‐hinged shear instead of frictional stick‐slip as the main and most dangerous mechanism of natural, induced and volcanic earthquakes in the earth's crust” considers extreme ruptures in intact rocks. Further study of this subject is a major challenge for deep underground science, earthquake and fracture mechanics, physics, and tribology.

show abstract

Superbrittleness of rocks at high confining pressure

Cited by 22 publications

References 38 publications

Shale Brittleness Index Based on the Energy Evolution Theory and Evaluation with Logging Data: A Case Study of the Guandong Block

Shale Brittleness Index Based on the Energy Evolution Theory and Evaluation with Logging Data: A Case Study of the Guandong Block

Fan‐hinged shear instead of frictional stick–slip as the main and most dangerous mechanism of natural, induced, and volcanic earthquakes in the earth's crust

New physics of supersonic ruptures

Contact Info

Product

Resources

About