Alaskan Earthquake, 27 March 1964: Vertical Extent of Faulting and Elastic Strain Energy Release

Because both faults and cleats exist in coal, sharp stress drops occur during loading when coal is deformed. These drops occur during the pre-peak stage and are accompanied by sudden energy releases. After a stress drop, the stress climbs slowly following a zigzag path and the energy accumulated during the pre-peak stage is unstable. A stress–strain curve is the basic tool used to evaluate the bursting liability of coal. Based on energy accumulation in an unsteady state, the pre-peak stress–strain curve is divided into three stages: pre-extreme, stress drop, and re-rising stage. The energy evolution of the specimen during each stage is analyzed. In this paper, an index called the effective elastic strain energy release rate (EESERR) index is proposed and used to evaluate the coal’s bursting liability. The paper shows that the propagation and coalescence of cracks is accompanied by energy release. The stress climb following a zigzag path prolongs the plastic deformation stage. This causes a significant difference between the work done by a hydraulic press during a laboratory uniaxial compression experiment and the elastic strain energy stored in the specimen during the experiment, so the evaluation result of the burst energy index would be too high. The determination of bursting liability is a comprehensive evaluation of the elastic strain energy accumulated in coal that is released when the specimen is damaged. The index proposed in this paper fully integrates the energy evolution of coal samples being damaged by loading, the amount of elastic strain energy released during the sample failure divided by the failure time is the energy release rate. The calculation method is simplified so that the uniaxial compressive strength and elastic modulus are included which makes the new index more universal and comprehensive. Theoretical analysis and physical compression experiments validate the reliability of the evaluation.

Download Full-text

Elastic strain energy release from fragmenting grains: Effects on fault rupture

Journal of Structural Geology ◽

10.1016/j.jsg.2011.11.004 ◽

2012 ◽

Vol 38 ◽

pp. 265-277 ◽

Cited By ~ 22

Author(s):

Timothy R.H. Davies ◽

Mauri J. McSaveney ◽

Carolyn J. Boulton

Keyword(s):

Energy Release ◽

Elastic Strain ◽

Strain Energy ◽

Elastic Strain Energy ◽

Strain Energy Release ◽

Fault Rupture

Download Full-text

Finite Element Simulation of Post-Elastic Strain Energy Release Rate for Ductile Thin Wall Structure

Proceedings of the Eighth International Conference on Civil and Structural Engineering Computing ◽

10.4203/ccp.73.69 ◽

2009 ◽

Author(s):

D. Tran

Keyword(s):

Finite Element ◽

Release Rate ◽

Elastic Strain ◽

Strain Energy ◽

Strain Energy Release Rate ◽

Elastic Strain Energy ◽

Strain Energy Release ◽

Wall Structure ◽

Thin Wall ◽

Element Simulation

Download Full-text

Study on the Instability Mechanism and Control Measures of a Roadway in a Mine with Retained Coal Pillars and Close Coal Seams

Shock and Vibration ◽

10.1155/2021/8871807 ◽

2021 ◽

Vol 2021 ◽

pp. 1-14

Author(s):

Huai-Qian Liu ◽

Lei Wang ◽

Lian-Chang Han ◽

Ping Liu ◽

Peng Zou

Keyword(s):

Energy Release ◽

Elastic Strain ◽

Strain Energy ◽

Coal Pillar ◽

Elastic Strain Energy ◽

Surrounding Rock ◽

Burial Depth ◽

Moderate Pressure ◽

Pillar Width ◽

Energy Accumulation

The deformation and instability of roadway surrounding rock reflect the processes of energy accumulation and release. To reveal the instability of roadway surrounding rock, based on the engineering geological conditions of a certain mine, this paper established a nonuniform superimposed stress model of a coal pillar, starting from the energy accumulation and release of the surrounding rock of the floor roadway after coal pillar failure. The essence of the deformation of the lower roadway was revealed, and the following conclusions were drawn: (1) The elastic strain energy accumulated in the lower roadway roof and upper coal pillar is related to not only the physical properties of the coal seam but also the distance between the coal pillar and surrounding rock, the caving height and shape, the burial depth, and the retained pillar width. (2) The elastic strain energy accumulated in the lower roadway roof and the upper coal pillar induced large displacements of the roadway due to the energy release during excavation. (3) It is proposed that the “stress relief degree” and failure morphology are used to identify zones in the rock and coal, and the two zoning modes have a high consistency. (4) The stress distribution in a narrow coal pillar should be calculated in segments. (5) Based on the zoning and energy release characteristics, the following control factors are suggested regarding the coal pillar width and roadway layout: (a) for the coal pillar, avoid the overlap or intersection of the peak values in the limit equilibrium zone and ensure a sufficient elastic zone; (b) arrange the roadway in shear slip Zone B-2 or the moderate pressure relief Zone B-2 to reduce the accumulation of elastic strain energy in the surrounding rock.

Download Full-text

The Effect of Local Yielding on the Strain-Energy Release Rate

Journal of Basic Engineering ◽

10.1115/1.3571230 ◽

1969 ◽

Vol 91 (4) ◽

pp. 852-854

Author(s):

P. L. Key

Keyword(s):

Energy Release Rate ◽

Energy Release ◽

Correction Factor ◽

Release Rate ◽

Strain Energy ◽

Strain Energy Release Rate ◽

Elastic Strain Energy ◽

Strain Energy Release ◽

Finite Width ◽

Dugdale Model

In a recent paper in the Journal of Basic Engineering [1], Forman presented numerical results for the strain-energy release rate of a crack in a finite width plate using the Dugdale model [2] of a yielded crack to describe the effects of local plastic flow. However, there appear to be several errors in the formulation of the problem by Forman. In addition, it is believed that an analytical rather than numerical approach to this problem would be more useful for applications. In this Note, an analytical form for a correction factor due to yielding is obtained for the elastic strain-energy release rate from an exact expression for the strain-energy release rale of the Dugdale model of a yielded crack in an infinite sheet. The effect of finite sheet width is treated as a separate correction factor.

Download Full-text

Brittle Characteristic and Microstructure of Sandstone under Freezing-Thawing Weathering

Advances in Civil Engineering ◽

10.1155/2020/8893278 ◽

2020 ◽

Vol 2020 ◽

pp. 1-12

Author(s):

Songtao Yu ◽

Junren Deng ◽

Hongwei Deng ◽

Feng Gao ◽

Jielin Li

Keyword(s):

Elastic Modulus ◽

Energy Release Rate ◽

Release Rate ◽

Elastic Strain ◽

Strain Energy ◽

Strain Energy Release Rate ◽

Elastic Strain Energy ◽

Strain Energy Release ◽

Peak Stress ◽

Brittleness Index

As an important property of rock material, brittleness plays a vital role in rock engineering. This paper raised the concept of elastic strain energy release rate and proposed an elastic strain energy release rate based brittleness index based on the most acceptable definition of brittleness. Mechanical and Nuclear Magnetic Resonance parameters of sandstone under various Freezing-Thawing (F-T) cycles are also acquired and analyzed. Then, the proposed brittleness index is used to compare with two recently proposed brittleness indices to verify its correctness and applicability. Finally, the brittleness index is applied to evaluate the brittle behavior of F-T cycles treated sandstone under uniaxial compression. The results show that elastic modulus, value of the postpeak modulus, and peak stress decrease with F-T cycles, and the porosity and microstructure develop with F-T cycles. The proposed brittleness index is highly related to F-T cycles, peak stress, porosity, and elastic modulus of sandstone that suffered recurrent F-T cycles. It declines exponentially with F-T cycles and porosity increase while growing exponentially with peak stress and elastic modulus increase.

Download Full-text

Multiscale effects caused by the fracturing and fragmentation of rock blocks in rock mass movement: Implications for rock avalanche propagation

10.5194/nhess-2021-127 ◽

2021 ◽

Author(s):

Qiwen Lin ◽

Yufeng Wang ◽

Yu Xie ◽

Qiangong Cheng ◽

Kaifeng Deng

Keyword(s):

Rock Mass ◽

Elastic Strain ◽

Strain Energy ◽

Mass Movement ◽

Elastic Strain Energy ◽

Rock Avalanche ◽

Strain Energy Release ◽

Rock Block ◽

Positive Trend ◽

Mass System

Abstract. Fracturing and fragmentation of rock blocks are important and universal phenomena during the propagation of rock avalanches. Here, the movement of a rectangular rock block characterized by different joint sets along an upper inclined and lower horizontal traveling path is simulated, aiming to quantify the fracturing and fragmentation effect of the block in propagation. The preset of the joint sets allows the block to break along the weak joint planes at the very beginning of fragmentation. With this design, the fracturing and fragmentation processes in the sliding rock block and their influences on energy transformation in the system are investigated. The results show that fragmentation can alter the horizontal velocities and kinetic energies of fragments in the block system with the front subblocks being accelerated and the rear part being obviously decelerated. Such energy conversion and transfer between the front and rear subblocks is attributed to the elastic strain energy release and transformation caused by fragmentation. The energy transfer induced by fragmentation is more efficient than that induced by collision. A positive trend between the kinetic energy increase of the front subblocks induced by fragmentation and the rock strength can be fitted well with a linear function. However, no good relationship is reached between the strain energy incremental ratio and travel distance, which implies that the fragmentation effects may be weakened with the increasing complexity of the fragmenting rock mass system. Three elastic strain wave release effects caused by rock fragmentation are further inferred and discussed based on simulation results.

Download Full-text