scholarly journals Estimation of Rock Burst Grades Using Rock Mass Strength

2020 ◽  
Vol 2020 ◽  
pp. 1-14
Author(s):  
Yalei Wang ◽  
Jinming Xu ◽  
Junshuai Xu ◽  
Chuanjiang Zhong
Keyword(s):  
Rock Mass ◽  
Rock Burst ◽  
Estimation Method ◽  
Western China ◽  
Actual Situation ◽  
Railway Tunnel ◽  
Good Reliability ◽  
Rock Mass Strength ◽  
Rock Bursts ◽  
Actual Rock

The traditional rock burst estimation method is usually based on the σc (rock strength) in practice, while the actual occurrence of rock burst depends more on the structure and strength of the rock mass. In this work, the actual rock bursts occurred in a railway tunnel project in Western China, and the σcm (rock mass strength) was calculated by the generalized Hoek–Brown criterion. According to the actual situation of rock bursts, a modified rock burst estimation criterion using the ratio of σcm to σmax (maximum geostress) was proposed. The influence of randomness on the reliability of rock burst estimation criterion was considered. The estimation results based on the traditional and modified method were furthermore compared with those of the actual rock bursts. The results show that σcm calculated by the generalized Hoek–Brown criterion may be considered well in the rock type and strength, construction condition, and structure features of the rock mass; the estimation results of rock burst using the ratio of σc to σmax are quite different from the actual situation, while those using the ratio of the σcm to σmax coincided relatively with the actual rock bursts; the ratios of σcm to σmax, which are greater than 0.167, 0.066 to 0.167, 0.012 to 0.066, and less than 0.012, are corresponded to the slight, medium, strong, and violent grades of the rock bursts, respectively; the randomness of data selection has certain influence on the rock burst estimation criterion, but the variation range is small; the modified estimation criterion of rock burst proposed in this work has a good reliability. The results presented herein are important for tunnel construction and the prevention of rock burst in the high geostress areas.

scholarly journals Mechanism of Rock Bursts Induced by the Synthetic Action of “Roof Bending and Rock Pillar Prying” in Subvertical Extra-Thick Coal Seams

2021 ◽  
Vol 9 ◽  
Author(s):  
Zhenhua Wu ◽  
Peng-Zhi Pan ◽  
Jianqiang Chen ◽  
Xudong Liu ◽  
Shuting Miao ◽  
...  
Keyword(s):  
Rock Mass ◽  
Coal Seam ◽  
Rock Burst ◽  
Roof Rock ◽  
High Energy ◽  
Coal Seams ◽  
Rock Bursts ◽  
Rock Pillar ◽  
Mining Depth ◽  
Rock Burst Mechanism

When studying the rock burst mechanism in subvertical extra-thick coal seams in the Wudong coal mine in Xinjiang, China, most studies focus on rock pillars, while the effect of the roof on rock bursts is usually ignored. In this paper, a rock burst mechanism in subvertical extra-thick coal seams under the control of a “roof-rock pillar” is proposed. A theoretical analysis is first performed to explain the effect of roof-rock pillar combinations on rock bursts in coal seams. Numerical modeling and microseismic analysis are implemented to further study the mechanism of rock burst. The main conclusions are as follows: 1) During the mining of the B3+6 coal seam, an obvious microseismic concentration phenomenon is found in both the roof and rock pillar of B3+6. The rock bursts exhibited obvious directionality, and its main failure characteristics are floor heave and sidewall heave, but there will also be some failures such as shoulder socket subsidence in some parts. 2) The stress transfer caused by rock pillar prying is the main reason for the large difference in rock burst occurrence near the vertical and extra thick adjacent coal seams under the same mining depth. 3) Under the same cantilever length, the elastic deformation energy of the roof is much greater than that of the rock pillar, which makes it easier to produce high-energy microseismic events. With an increasing mining depth, the roof will become the dominant factor controlling the occurrence of rock bursts. 4) The high-energy event produced by the rock mass fracture near the coal rock interface easily induces rock bursts, while the high-energy event produced by the fracture at the far end of the rock mass is less likely to induce rock burst. 5) Roof deformation extrusion and rock pillar prying provide high static stress conditions for the occurrence of rock bursts in the B3+6 coal seam. The superposition of the dynamic disturbance caused by roof and rock pillar failure and the high static stress of the coal seam is the main cause of rock burst in the B3+6 coal seam.

scholarly journals Rock Burst Mechanics: Insight from Physical and Mathematical Modelling

10.14311/1071 ◽  
2008 ◽  
Vol 48 (6) ◽  
Author(s):  
J. Vacek ◽  
J. Vacek ◽  
J. Chocholoušová
Keyword(s):  
Rock Mass ◽  
Mathematical Modelling ◽  
Mathematical Models ◽  
Rock Burst ◽  
Material Properties ◽  
Open Space ◽  
Time Dependent ◽  
Rock Bursts ◽  
Uranium Mines ◽  
Physical And Mathematical Models

Rock burst processes in mines are studied by many groups active in the field of geomechanics. Physical and mathematical modelling can be used to better understand the phenomena and mechanisms involved in the bursts. In the present paper we describe both physical and mathematical models of a rock burst occurring in a gallery of a coal mine.For rock bursts (also called bumps) to occur, the rock has to possess certain particular rock burst properties leading to accumulation of energy and the potential to release this energy. Such materials may be brittle, or the rock burst may arise at the interfacial zones of two parts of the rock, which have principally different material properties (e.g. in the Poíbram uranium mines).The solution is based on experimental and mathematical modelling. These two methods have to allow the problem to be studied on the basis of three presumptions:· the solution must be time dependent,· the solution must allow the creation of cracks in the rock mass,· the solution must allow an extrusion of rock into an open space (bump effect). 

Finite Element Analysis of Dongjusi Railway Tunnel within Hard Rock Mass Based on the Unified Rock Mass Strength Criterion

2007 ◽  
Vol 353-358 ◽  
pp. 2994-2997
Author(s):  
Yuan Hua ◽  
Tai Quan Zhou ◽  
Guo Liang Dai
Keyword(s):  
Rock Mass ◽  
Principal Stress ◽  
Hard Rock ◽  
Plastic Material ◽  
Strength Criterion ◽  
Intermediate Principal Stress ◽  
Stress Effect ◽  
Railway Tunnel ◽  
Rock Mass Strength ◽  
Intermediate Principal Stress Effect

The twin shear strength criterion has been proposed to consider the intermediate principal stress effect on the rock mass strength. The unified rock mass strength criterion could consider the intermediate principal stress effect on the rock mass strength. The unified rock mass elasto-plastic material model is implemented in ABAQUS user interface. As a case for study, the stability analysis of Dongjusi railway tunnel within hard rock mass is studied using the unified rock mass strength material. For comparison, the Hoek-Brown empirical strength criterion is also chosen for the rock mass material modeling. The computation results show that the plastic zone calculated using the unified rock mass strength criterion is smaller than that using the Hoek-Brown empirical strength criterion. The railway tunnel lining structure is designed according to the unified rock mass strength criterion and greatly makes use of the rock mass potential strength, which decreases engineering cost.

ROCK MASS STRENGTH IN RELATION TO LANDSLIDE PROGRESSION

2018 ◽  
Author(s):  
Brooke M. Hornney ◽  
◽  
Marlene C. Villeneuve ◽  
Jonathan Davidson
Keyword(s):  
Rock Mass ◽  
Rock Mass Strength

Fault controls on spatial variation of fracture density and rock mass strength within the Yarlung Tsangpo Fault damage zone (southeastern Tibet)

2021 ◽  
pp. 106238
Author(s):  
Xueliang Wang ◽  
Giovanni Battista Crosta ◽  
John J. Clague ◽  
Douglas Stead ◽  
Juanjuan Sun ◽  
...  
Keyword(s):  
Rock Mass ◽  
Spatial Variation ◽  
Damage Zone ◽  
Fracture Density ◽  
Rock Mass Strength ◽  
Fault Damage Zone ◽  
Yarlung Tsangpo ◽  
Southeastern Tibet

scholarly journals Directional Hydraulic Fracturing (DHF) of the Roof, as an Element of Rock Burst Prevention in the Light of Underground Observations and Numerical Modelling

Energies ◽  
2021 ◽  
Vol 14 (3) ◽  
pp. 562
Author(s):  
Marek Jendryś ◽  
Andrzej Hadam ◽  
Mateusz Ćwiękała
Keyword(s):  
Rock Mass ◽  
Hydraulic Fracturing ◽  
Coal Mining ◽  
Rock Burst ◽  
Coal Mine ◽  
Seismic Activity ◽  
Black Coal ◽  
Directional Hydraulic Fracturing ◽  
Before And After ◽  
The Face

The following article analyzes the effectiveness of directional hydraulic fracturing (DHF) as a method of rock burst prevention, used in black coal mining with a longwall system. In order to define changes in seismic activity due to DHF at the “Rydułtowy” Black Coal Mine (Upper Silesia, Poland), observations were made regarding the seismic activity of the rock mass during coal mining with a longwall system using roof layers collapse. The seismic activity was recorded in the area of the longwall itself, where, on a part of the runway, the rock mass was expanded before the face of the wall by interrupting the continuity of the rock layers using DHF. The following article presents measurements in the form of the number and the shock energy in the area of the observed longwall, which took place before and after the use of DHF. The second part of the article unveils the results of numerical modeling using the discrete element method, allowing to track the formation of goafs for the variant that does not take DHF into consideration, as well as with modeled fractures tracing DHF carried out in accordance with the technology used at “Rydułtowy” coal mine.

Rock Mass Strength Assessment for Bedrock Landsliding

1996 ◽  
Vol II (3) ◽  
pp. 325-338 ◽  
Author(s):  
K. M. SCHMIDT ◽  
D. R. MONTGOMERY
Keyword(s):  
Rock Mass ◽  
Strength Assessment ◽  
Rock Mass Strength
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