Comparison between different estimators of the degree of rock mass fracturing

Abstract The aim of this study was to examine the effect of the temperature of surrounding rocks on enthalpy and temperature of air flowing along several model mine workings. Long workings surrounded by non- -coal rocks as well longwall gates surrounded by coal were taken into consideration. Computer-aided simulation methods were used during the study. At greater depths the amount of moisture transferred into a mine working from the rock mass is two orders of magnitude smaller than the moisture that comes from external (technological) sources, mainly from coal extraction-related processes, therefore in the equation describing temperature changes only the terms representing the flux of heat from rocks were included. The model workings, for calculation purposes, were divided into sections, 50 m in length each. For each of the sections temperature of its ribs and temperature and stream of enthalpy of air flowing along it were calculated with the use of the finite differences method. For workings surrounded by non-coal rocks two variant calculations were carried out, namely with or without technological sources of heat. For coal surrounded workings (longwall gates) a new method for determination of heat from coal oxidation was developed, based on the findings by Cygankiewicz J. (2012a, 2012b). Using the results of a study by J.J. Drzewiecki and Smolka (1994), the effects of rock mass fracturing on transfer of heat into the air stream flowing along a working were taken into account.

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Moment tensors of mining tremors: Detection tool of the mode of rock-mass fracturing

Third Passive Seismic Workshop - Actively Passive 2011 ◽

10.3997/2214-4609.20145317 ◽

2011 ◽

Author(s):

J. Sileny ◽

E. Latter ◽

A. Milev

Keyword(s):

Rock Mass ◽

Moment Tensors ◽

Detection Tool ◽

Rock Mass Fracturing ◽

Mining Tremors

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Classification Method and Application of Rock Fracture Ability by Supercritical CO2 Blasting

Shock and Vibration ◽

10.1155/2022/7973016 ◽

2022 ◽

Vol 2022 ◽

pp. 1-11

Author(s):

Xiaohong Zhu ◽

Jianhong Jia ◽

Zhongwei Cai

Keyword(s):

Rock Mass ◽

Supercritical Co2 ◽

Evaluation Method ◽

Cloud Model ◽

Rock Fracture ◽

Evaluation Index System ◽

Classification Theory ◽

Classification Method ◽

Entropy Weight ◽

Rock Mass Fracturing

In order to study the fracture ability classification of rock mass under the cracking action of supercritical CO2 phase transition, based on the classification theory of rock mass in blasting engineering, an analytic hierarchy process (AHP)-entropy weight method (EWM) and the cloud model classification method for rock mass cracking under CO2 phase transformation are proposed. In this method, rock density, rock tensile strength, rock wave impedance, and rock mass integrity coefficient are used as the factors to determine the level of rock mass fracturing, and the evaluation index system of rock mass fracturing is established. Through this evaluation method, the rock mass in a reconstruction project section of Nyingchi, Tibet, is classified and evaluated. The results present that this new classification method of rock mass fracture ability uses AHP–EWM to carry out the weight distribution of the classification index. In addition, it is combined with the cloud model for the classification division, overcoming the traditional classification method fixed with appraisal pattern flaw. Therefore, it has validity and feasibility. According to the characteristics of fracture ability, the rock masses in the area to be rebuilt on the Tibet Highway are divided into grade II, grade III, and grade IV, which provides scientific guidance for the construction of the project.

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Multiconfiguration GPR measurements for geometric fracture characterization in limestone cliffs (Alps)

Geophysics ◽

10.1190/1.2194526 ◽

2006 ◽

Vol 71 (3) ◽

pp. B85-B92 ◽

Cited By ~ 57

Author(s):

Mathieu Jeannin ◽

Stéphane Garambois ◽

Colette Grégoire ◽

Denis Jongmans

Keyword(s):

Rock Mass ◽

Test Site ◽

Fracture Characterization ◽

Rock Stability ◽

Transmission Data ◽

Velocity Image ◽

Maximum Penetration ◽

Rock Mass Fracturing ◽

Ground Penetrating

Rock-mass fracturing is a key parameter in rock-fall hazard assessment. However, traditional geologic observations can provide information only about discontinuities at the surface. In this case study, detailed ground-penetrating-radar (GPR) measurements (with antennas of [Formula: see text], [Formula: see text], [Formula: see text], and [Formula: see text]) were conducted on a test site, using different acquisition configurations deployed on vertical cliff faces. Conventional 2D profile data, common-midpoint (CMP) survey data, and transmission data were acquired to evaluate the potential use of radar waves to characterize the geometry and properties of the major discontinuities (fractures) within a Mesozoic limestone massif. Results showed that the continuity and geometry (orientation and dip) of the major observed fractures, which are crucial parameters for assessing rock stability, can be obtained by combining vertical and horizontal profiles measured along the cliff. We used [Formula: see text] antennae and reached a maximum penetration of [Formula: see text], which limits the technique to rock volumes of a few tens of thousands of cubic meters. We observed significant differences in reflectivity along the detected fractures, which suggests that the fractures’ characteristics vary in the rock mass. We used transmission data to obtain a radar velocity image. Although the results were consistent with radar profiles on the cliff, they showed that the technique has little utility, beyond that of more traditional GPR methods, for delineating fractures in a rock mass.

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