scholarly journals Estimating the rockburst hazard of hard rocks based on laboratory test results

2019 ◽  
Vol 129 ◽  
pp. 01008
Author(s):  
Iuliia Fedotoval ◽  
Nikolay Kuznetcov ◽  
Eduard Kasparyan
Keyword(s):  
Rock Mass ◽  
Rock Fracture ◽  
Standard Test ◽  
Standard Equipment ◽  
Rock Classification ◽  
Rockburst Hazard ◽  
Hazard Degree ◽  
Laboratory Test Results ◽  
Dynamic Fractures ◽  
Deformation Patterns

The results of laboratory tests of samples are used to estimate rock proneness to dynamic fractures, in particular, by brittleness index. A common drawback of the approaches in use is that they do not expressly consider the main condition of dynamic rock fracture – rock mass ability to accumulate energy when loaded. The article discusses the results of studies of the nature of elastic energy accumulation during loading and deformation of samples of various rocks under uniaxial compression in order to assess the degree of their explosion. The approach is original as it studies the deformation curve of rocks at the pre-peak stage that may be obtained with any standard equipment without the use of special-purpose test (“rigid”) devices. Results of the studies conducted on standard test devices have allowed us to identify two different deformation patterns for the rock type tested with further establishment of criteria of rock classification by the degree of proneness to dynamic fractures. This approach is of practical value as it specifies the geomechanics zoning method of the rock mass and improves the assessment of rockburst hazard degree of specific areas at deposits being developed.

Influence exerted by underground excavation shape and by effective stresses on the formation of a tensile strain zone at a depth greater than 1 km

2020 ◽  
pp. 67-75
Author(s):  
Van Min Nguyen ◽  
V. A. Eremenko ◽  
M. A. Sukhorukova ◽  
S. S. Shermatova
Keyword(s):  
Rock Mass ◽  
Cross Sections ◽  
Tensile Strain ◽  
Rock Fracture ◽  
Strain Analysis ◽  
Surrounding Rock ◽  
Underground Excavation ◽  
Secondary Stress ◽  
Principal Stresses ◽  
Mining Depth

The article presents the studies into the secondary stress field formed in surrounding rock mass around underground excavations of different cross-sections and the variants of principal stresses at a mining depth greater than 1 km. The stress-strain analysis of surrounding rock mass around development headings was performed in Map3D environment. The obtained results of the quantitative analysis are currently used in adjustment of the model over the whole period of heading and support of operating mine openings. The estimates of the assumed parameters of excavations, as well as the calculations of micro-strains in surrounding rock mass by three scenarios are given. During heading in the test area in granite, dense fracturing and formation of tensile strain zone proceeds from the boundary of e ≥ 350me and is used to determine rough distances from the roof ( H roof) and sidewalls ( H side) of an underground excavation to the 3 boundary e = 350me (probable rock fracture zone). The modeling has determined the structure of secondary stress and strain fields in the conditions of heading operations at great depths.

Rockburst-hazard criterion of rock mass

1999 ◽  
Vol 35 (6) ◽  
pp. 598-601 ◽  
Author(s):  
A. A. Yeryomenko ◽  
A. P. Gaidin ◽  
V. A. Vaganova ◽  
V. A. Yeryomenko
Keyword(s):  
Rock Mass ◽  
Rockburst Hazard

PHYSICAL PREREQUISITES FOR GAS PERMEABILITY SIMULATION OF MINED ROCK MASS

2021 ◽  
pp. 78-84
Author(s):  
Oleksandr Shashenko ◽  
◽  
Vladyslava Cherednyk ◽  
Natalia Khoziaikina ◽  
Dmitro Shashenko ◽  
...  
Keyword(s):  
Rock Mass ◽  
Physical Model ◽  
Rock Sample ◽  
Coal Mass ◽  
Dynamic Processes ◽  
Deformation Diagram ◽  
Gas Dynamic ◽  
Laboratory Test Results ◽  
Deformation Properties ◽  
Complete Deformation

Purpose. Justification of the gas collectors formation physical model on the basis of research of conformity of permeability of rock mass to the full diagram of rock sample deformation. Methodology consists in sequential analysis of the stages of the complete deformation diagram of the rock specimen under “hard” loading, comparing them with the stages of formation of the high stress zone in front of the lava bottom and statistical analysis of laboratory test results. Results. Based on the rock’s deformation properties analysis and their comparison with the rock sample full deformation diagram, the physical model of formation of gas reservoirs during the development of gas-saturated coal seam is substantiated. Within the solved problem framework, four stages of the complete deformation process are analyzed, namely: elastic, at the limit of strength, out-of-bounds stage and equivoluminal flow zone. The gas collector boundaries, which are the characteristic points of the rock sample deformation diagram in specified deformations mode (the limit of elastic strength and the limit of final strength) are determined. It is proved that the structural and textural features of the coal mass in connection with the course of gas-dynamic processes are manifested in the change in the pores and cracks volume contained in it, which together make the filtration space. Knowledge regarding the transfer of the permeability changes established regularities and free methane accumulation zones formation to the real rock mass, if the process of its forgery is considered as a consistent change of geomechanical states of rocks, is obtained. Scientific novelty lies in the first substantiated possibility of modeling the stress state before the longwall face by equivalent stages of the rock sample destruction in the given deformations mode. Gradual comparative analysis of the internal mechanism of rock samples deformation along the complete deformation diagram allowed establishing causal relationships between geomechanical and gas-dynamic processes in coal mass, and qualitatively characterizing general trends in permeability and volumetric expansion in changes of these samples. Practical value of the work lies in the justification of the principle of construction of a digital geomechanical model for the detection of man-made gas collectors in a mined coal mass.

Research on the Cavern Stability and Rock Fracture with Different Joint Groups

2012 ◽  
Vol 188 ◽  
pp. 96-100 ◽  
Author(s):  
Hai Ping Ma ◽  
Wei Shen Zhu ◽  
Song Yu ◽  
Jing Wang
Keyword(s):  
Rock Mass ◽  
Loading Condition ◽  
Fracture Process ◽  
Process Analysis ◽  
Rock Fracture ◽  
Rock Stability ◽  
Joint Rock Mass ◽  
Deformation Stress ◽  
Cavern Stability ◽  
Joint Rock

The numerical simulation using DDARF was carried out to analysis the rock samples with two and four cracks under uniaxial loading condition. Contrastive research was made about the fracture process analysis of rock mass with joints sets at the three different angles. The rock stability with difference of joint rock mass was compared when the lateral coefficient of initial stress varied. It is shown that distribution of joint groups will bring effects on rock surroundings in controlling deformation, stress status and stability.

Study of Seepage Properties of Fractured Rock Mass Based on Improved K-Means Clustering Algorithm

2013 ◽  
Vol 405-408 ◽  
pp. 310-315
Author(s):  
Hai Qing Guo ◽  
Bo Wen ◽  
Xiao Feng Bai
Keyword(s):  
Rock Mass ◽  
Clustering Algorithm ◽  
Fractured Rock ◽  
Rock Fracture ◽  
Fractured Rock Mass ◽  
Dam Foundation ◽  
Fracture Geometry ◽  
Basic Task ◽  
Matlab Program ◽  
Seepage Properties

Seepage properties of fractured rock mass are of prime importance for hydraulic engineering and accurate description of rock fracture geometry parameters is an important and basic task in rock hydraulics. In this paper, an improved K-means clustering algorithm for structural plane of fractured rock mass was first brought forward and the corresponding Matlab program for discontinuity orientations partitioning was compiled and then used in the fitting analysis of dominant orientations of certain dam foundation rock mass. On this basis, combining calculation formulas of multi-group fractures, the permeability tensor and principle value was calculated for the actual dam foundation. The results provide a theoretical and computational reference for other similar projects.

scholarly journals Determining the REV for Fracture Rock Mass Based on Seepage Theory

Geofluids ◽  
2017 ◽  
Vol 2017 ◽  
pp. 1-8 ◽  
Author(s):  
Lili Zhang ◽  
Lu Xia ◽  
Qingchun Yu
Keyword(s):  
Rock Mass ◽  
Fractured Rock ◽  
Engineering Application ◽  
Existence Condition ◽  
Analysis Tool ◽  
Fractured Rock Mass ◽  
Rock Classification ◽  
Fracture Spacing ◽  
Fractured Rock Masses

Seepage problems of the fractured rock mass have always been a heated topic within hydrogeology and engineering geology. The equivalent porous medium model method is the main method in the study of the seepage of the fractured rock mass and its engineering application. The key to the method is to determine a representative elementary volume (REV). The FractureToKarst software, that is, discrete element software, is a main analysis tool in this paper and developed by a number of authors. According to the standard of rock classification established by ISRM, this paper aims to discuss the existence and the size of REV of fractured rock masses with medium tractility and provide a general method to determine the existence of REV. It can be gleaned from the study that the existence condition of fractured rock mass with medium tractility features average fracture spacing smaller than 0.6 m. If average fracture spacing is larger than 0.6 m, there is no existence of REV. The rationality of the model is verified by a case study. The present research provides a method for the simulation of seepage field in fissured rocks.

scholarly journals Failure Mechanisms of Brittle Rocks under Uniaxial Compression

2017 ◽  
Vol 47 (3) ◽  
pp. 59-80 ◽  
Author(s):  
Taoying Liu ◽  
Ping Cao
Keyword(s):  
Rock Mass ◽  
Crack Initiation ◽  
Failure Mechanism ◽  
Shear Crack ◽  
Fractured Rock ◽  
Rock Fracture ◽  
Wing Crack ◽  
Rock Bridge ◽  
Brittle Rocks ◽  
Shear Connection

AbstractThe behaviour of a rock mass is determined not only by the properties of the rock matrix, but mostly by the presence and properties of discontinuities or fractures within the mass. The compression test on rock-like specimens with two prefabricated transfixion fissures, made by pulling out the embedded metal inserts in the pre-cured period was carried out on the servo control uniaxial loading tester. The influence of the geometry of pre-existing cracks on the cracking processes was analysed with reference to the experimental observation of crack initiation and propagation from pre-existing flaws. Based on the rock fracture mechanics and the stress-strain curves, the evolution failure mechanism of the fissure body was also analyzed on the basis of exploring the law of the compression-shear crack initiation, wing crack growth and rock bridge connection. Meanwhile, damage fracture mechanical models of a compression-shear rock mass are established when the rock bridge axial transfixion failure, tension-shear combined failure, or wing crack shear connection failure occurs on the specimen under axial compression. This research was of significance in studying the failure mechanism of fractured rock mass.

scholarly journals Considerations in Fracture of Rock Mass by Using Trial Hydraulic Rock Fracture Machine.

1997 ◽  
pp. 249-258
Author(s):  
Yoshinori Inada ◽  
Koichi Nohara ◽  
Takeshi Uehara ◽  
Takashi Matsumoto ◽  
Masaaki Okamoto ◽  
...  
Keyword(s):  
Rock Mass ◽  
Rock Fracture

scholarly journals Soft Computing Based Prediction of Support Pressure in Tunnels

2019 ◽  
Vol 8 (6) ◽  
pp. 856-863 ◽  
Keyword(s):  
Neural Network ◽  
Rock Mass ◽  
Linear Regression Analysis ◽  
Network Models ◽  
Empirical Models ◽  
Support Pressure ◽  
Neural Network Models ◽  
Connection Weight ◽  
Rock Classification ◽  
Tunnel Support

Prediction of Tunnel support pressure up to an accurate and reliable degree is difficult, but of utmost importance. Empirical models are available with different set of parameters, mostly are based on the rock classification parameters. A feed forward neural network based predictive models from the data collected from literature for the Himalayan tunnels have been developed. The input variables in the developed neural network models were depth of over burden, radius of tunnel, normalised closure. The fourth input variable was rock mass quality or rock mass number or rock mass rating. The output was a support pressure. Sensitivity analysis relating the variables affecting the support pressure has been performed. The developed neural network models were compared with models developed based on the multiple linear regression analysis as well as with empirical models already available in literature. Finally, model equations have been presented based on the connection weight.

scholarly journals Investigating the variation of the fields of elastic stresses in the rock mass when developing the Peschanskoye deposit

2020 ◽  
pp. 19-28
Author(s):  
Lipin Iakov ◽  
◽  
Sentiabov Sergei ◽  
Krinitsyn Roman ◽  
◽  
...  
Keyword(s):  
Rock Mass ◽  
Stress State ◽  
Rock Burst ◽  
Extreme Values ◽  
Rockburst Hazard ◽  
Elastic Stresses ◽  
Ore Bodies ◽  
Study Parameter ◽  
State Variation ◽  
The Impact

Research aim is to study parameter variations in the stress state of the rock mass to ensure safe and efficient mining of the Peschanskoye magnetite deposit (Northern Ural) to the full depth, which has been carried out by Severopeschanskaya mine since 1958 in a complex of hard rock at a depth of 200 to 700 m. Blind, thick, and steep ore bodies are developed by a block-caving method with ore breaking to a clamped medium. From a depth of 400 m, the field is classified as rock burst hazardous. The first rock burst was recorded in 1981 at a depth of 450 m. Research methodology includes full-scale experimental measurements of the rock and ore mass stress state at accessible depths and horizons of the deposit, establishing patterns of stress growth with depth, as well as long-term (since 1990) geo-deformational monitoring of an untouched rock mass stress level in time. Research results analysis has allowed to establish the patterns in stress-strain state changes during mining. Gradients of gravitational and tectonic stresses growth with depth are determined. Alternating (astrophysical) stresses are highlighted in a special line, the extreme values of which are linked chronologically with various information factors. Conclusions. The determined values of rock mass natural stress state variation parameters in combination with the established stresses around the workings and goafs (technogenic impact) make it possible to take into account the main tempo-spatial factors of the impact made by the mentioned loads when selecting rockburst-safe and effective mining parameters for underground geotechnology both at the top horizons when applying controlled collapse of overlying blind deposits and in the prevention of rockburst hazard in the lower horizons of the developed field

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