scholarly journals Simple Correlations between Rock Abrasion and Other Significant Rock Properties for Rock Mass and Intact Quartzite

2017 ◽  
Vol 07 (02) ◽  
pp. 194-207
Author(s):  
Scott Ureel ◽  
Moe Momayez
Keyword(s):  
Rock Mass ◽  
Rock Properties ◽  
Rock Abrasion

The Mechanics of Rock Failure Due to Water Jet Impingement

1974 ◽  
Vol 14 (01) ◽  
pp. 10-18 ◽  
Author(s):  
S.E. Forman ◽  
G.A. Secor
Keyword(s):  
Rock Mass ◽  
Stress Field ◽  
Pressure Distribution ◽  
Pore Pressure ◽  
Static Pressure ◽  
Jet Impingement ◽  
Water Jet ◽  
Rock Properties ◽  
Rock Surface ◽  
Pressure Loading

Abstract The initiation of fracture in a rock mass subjected to the impingement of a continuous water jet has been studied. The jet is assumed to place a quasistatic pressure loading on the surface of the rock, which is treated as a saturated, porous-elastic, isotropic, and homogeneous half-space. While this pressure loading is held constant, the impinging water flows through the rock according to Darcy's law and pressurizes the fluid in the pores. The pore pressure distribution couples with the stress field due to the surface loading to produce an effective stress field, which can start tensile fracturing directly under the load. At various time intervals after initial impingement, the effective-stress field is computed using finite element methods and the results, together with the Griffith criterion for tensile failure, produce the loci of the zones of fracture initiation. The behavior of these zones is displayed as a function of the two jet parameters - pressure and nozzle diameter - and the five rock properties: Young's modulus, Poisson's ratio, tensile strength, porosity and permeability, and time. To experimentally verify that pore pressure plays an important role in the mechanism of rock fracture due to jet impingement, thin sheets of copper (0.001 to 0.005 in.) were placed between a continuous jet (up to 20,000 psi) and the surface of a block of Indiana limestone. The purpose of the copper sheet was to allow the pressure of the jet to be transmitted to the rock, but to prevent water from entering the pore structure. Using pressure substantially greater than the threshold pressure of pressure substantially greater than the threshold pressure of limestone (3,500 psi) where penetration always occurred in the absence of the copper sheet, placement of the sheet was sufficient to prevent any visible damage from occurring to the rock surface, provided the jet did not penetrate the copper first. provided the jet did not penetrate the copper first Introduction The method by which a water jet penetrates and fractures a rock mass is highly complicated and poorly understood. This is mainly because the rock is subjected during the impact to several separate processes, each of which can cause failure. Failure can result from the effects of dynamic stress waves, static pressure loading and erosion. The degree of failure caused by each mechanism is, of course, dependent on the rock properties and jet parameters. parameters. In the first few microseconds of impingement, a subsonic jet pressure on the rock surface reaches the so-called "water hammer" pressure on the rock surface reaches the so-called "water hammer" pressure of pvv(c) and then drops to the nozzle stagnation pressure pressure of pvv(c) and then drops to the nozzle stagnation pressure of approximately 1/2 pv2. (p = fluid density, v = jet velocity, and v(c) = velocity of compression waves in the liquid.) During this initial period of impact, large-amplitude compressive waves are caused to emanate from the point of impingement. Upon reflection off a free surface, these waves become tensile and can cause spalling failures. This mode of failure is usually important with pulsed jet impingement. For continuous jets the spalling effects are small and will be neglected for this study. During the impingement process, the water of the jet flows into the accessible pore space of the rock mass. Since in a continuous jetting process the jet applies a quasi-static pressure loading to the rock surface, the water in the pores is pressurized while the surrounding rock mass is simultaneously stressed. The intent of this paper is to describe the role played by this static pressure loading coupled with the pore-pressure distribution, or pressure loading coupled with the pore-pressure distribution, or the "effective stress," in the first moments of penetration. In studying the process, we will take into account the influence of jet parameters and rock properties. In the course of the impingement process, the jet pressure loading is constantly being redistributed over the crater as it is formed. During this progressive removal of material, erosion is also contributing. The process of erosion is in itself highly complex, so no attempt will be made to characterize it here. EFFECTS OF STATIC PRESSURE DISTRIBUTION-ZERO PORE PRESSURE It has been shown by Leach and Walker that a water jet emanating from the nozzle depicted in Fig. 1 applies a quasi-scatic pressure loading to the surface upon which it is impinging. SPEJ P. 10

Static and Dynamic Elastic Modulus of Jointed Rock Mass

2010 ◽  
Vol 1 (2) ◽  
pp. 89-112
Author(s):  
T. G. Sitharam ◽  
M. Ramulu ◽  
V. B. Maji
Keyword(s):  
Rock Mass ◽  
Elastic Modulus ◽  
Jointed Rock ◽  
Jointed Rock Mass ◽  
Intact Rock ◽  
Rock Properties ◽  
Dynamic Elastic Modulus ◽  
Joint Factor ◽  
Joint Frequency ◽  
Joint Inclination

In this paper the compressive strength/elastic modulus of the jointed rock mass was estimated as a function of intact rock strength/modulus and joint factor. The joint factor reflects the combined effect of joint frequency, joint inclination and joint strength. Therefore, having known the intact rock properties and the joint factor, jointed rock properties can be estimated. The test results indicated that the rock mass strength decreases with an increase in the joint frequency and a sharp transition was observed from brittle to ductile behaviour with an increase in the number of joints. It was also found that the rocks with planar anisotropy exhibit the highest strength in the direction perpendicular to the anisotropy and the lowest at an inclination of 30o-45o in jointed samples. The anisotropy of the specimen influences the dynamic elastic modulus more than the static elastic modulus. The results were also compared well with the published works of different authors for different type of rocks.

Anisotropic velocity tomography: A case study in a near‐surface rock mass

Geophysics ◽  
1993 ◽  
Vol 58 (12) ◽  
pp. 1748-1763 ◽  
Author(s):  
R. G. Pratt ◽  
W. J. McGaughey ◽  
C. H. Chapman
Keyword(s):  
Rock Mass ◽  
Fault Zone ◽  
Seismic Velocity ◽  
Anisotropic Media ◽  
Rock Properties ◽  
Initial Assessment ◽  
Borehole Data ◽  
Near Surface ◽  
Crown Pillar ◽  
Velocity Tomography

Cross‐borehole data were acquired in the surface crown pillar of a massive sulfide ore mine. The data consist of five, two‐dimensional (2-D), cross‐borehole panels, each with approximately 900 source‐receiver pairs. The panels were located within the crown pillar at either side of and within a major subvertical fault zone that intersects the orebody. An initial analysis of the data indicates that the bedrock containing the orebody is seismically anisotropic. A rigorous analysis of the traveltimes using anisotropic velocity tomography confirms the initial assessment that anisotropy exists within the crown pillar rock mass. Anisotropic velocity tomography is the generalization of tomographic methods to anisotropic media. As in any geophysical problem, the data are insufficient to completely resolve the distributions of the rock properties at all scale lengths; we use external constraints on the roughness of the final solution to ensure an algebraically well‐posed problem. Plots of the data residuals (the “traveltime surfaces”) are an essential tool in determining an optimal level of constraint. Of equal importance are plots of the relationship between the solution roughness and the rms level of the residuals. The final results of anisotropic velocity tomography are a set of images (tomograms) of the velocity and selected anisotropy parameters for the five panels. Our images do not contain the distortions typically exhibited when using isotropic tomography in anisotropic media. The velocity tomograms clearly show the geometry of the overburden contact at the top of the bedrock. The anisotropy tomograms show a decrease in anisotropy with depth on two of the panels. They also show a decrease in anisotropy with proximity to the fault zone. These features of the seismic velocity anisotropy are consistent with observations of fracture orientation and distribution. The results of the crosshole data interpretation contribute to the overall site investigation and provide a reliable interrogation of the bulk properties of the rock mass.

scholarly journals Characterization of Weathered Soft Rock Mass by Index Tests

2018 ◽  
Vol 1 (1) ◽  
Author(s):  
Fernandes Leão M
Keyword(s):  
Rock Mass ◽  
Soft Rock ◽  
Point Load ◽  
Load Test ◽  
Rock Properties ◽  
Morphological Description ◽  
Durability Test ◽  
Stability Issues ◽  
Weathering Zone

The understanding of geotechnical and geomechanical rock mass behavior is challenging, mainly regarding weathered parts, since they may trigger stability issues. Soft Rocks, as phyllite, are known to enhance these problems. In this case, a road cut on a highway between the cities of Ouro Preto and Mariana (MG – Brazil) was studied, showing a particular weathering zone with changing conditions. After morphological description and geological fragmentation (using geological hammer, the Schmidt hammer and a switchblade) of the weathering zone, tests were done on rock matrix and rock mass in order to identify the discontinuity features. Physical properties were determined by physical index, using the point load test and slake durability test. The results permit to define the weathering zone, showing some huge anisotropy and heterogeneity in the rock properties.

Static and Dynamic Elastic Modulus of Jointed Rock Mass

2012 ◽  
pp. 110-133
Author(s):  
T. G. Sitharam ◽  
M. Ramulu ◽  
V. B. Maji
Keyword(s):  
Rock Mass ◽  
Elastic Modulus ◽  
Jointed Rock ◽  
Jointed Rock Mass ◽  
Intact Rock ◽  
Rock Properties ◽  
Dynamic Elastic Modulus ◽  
Joint Factor ◽  
Joint Frequency ◽  
Joint Inclination

In this paper the compressive strength/elastic modulus of the jointed rock mass was estimated as a function of intact rock strength/modulus and joint factor. The joint factor reflects the combined effect of joint frequency, joint inclination and joint strength. Therefore, having known the intact rock properties and the joint factor, jointed rock properties can be estimated. The test results indicated that the rock mass strength decreases with an increase in the joint frequency and a sharp transition was observed from brittle to ductile behaviour with an increase in the number of joints. It was also found that the rocks with planar anisotropy exhibit the highest strength in the direction perpendicular to the anisotropy and the lowest at an inclination of 30o-45o in jointed samples. The anisotropy of the specimen influences the dynamic elastic modulus more than the static elastic modulus. The results were also compared well with the published works of different authors for different type of rocks.

Rock mass damaging investigation through the analysis of microseismic monitoring data collected on rock masses

2021 ◽  
Author(s):  
Danilo D'Angiò ◽  
Luca Lenti ◽  
Salvatore Martino
Keyword(s):  
Rock Mass ◽  
Damping Ratio ◽  
Inelastic Strain ◽  
Microseismic Monitoring ◽  
Monitoring Data ◽  
Rock Properties ◽  
Analysis Approach ◽  
Monitoring Networks ◽  
Rock Masses ◽  
Main Research

<p>Rock mass damaging investigation is a main research topic in the ambit of rock fall hazard assessment. Roads and railways interruptions, as well as damages of buildings, are among the main inconveniences due to the detachment of unstable sectors of highly jointed rock masses. The contribution of rock mass creep together with natural and anthropic forcings leads to the accumulation of inelastic strain within the rock mass and to the formation of new joints or to the extension and movement of the pre-existing ones. The associated stress release produces tiny vibratory signals (known as microseismic emissions) that can be detected by on-site installed microseismic monitoring networks. Monthly and annual microseismic monitoring data can provide information on seismicity increase over certain periods and on the deterioration of rock properties as the elastic moduli. However, other seismic attributes may support the comprehension of rock mass damaging processes. In particular, the analysis over time of the damping ratio associated with the microseismic emissions could indicate transient and permanent changes within the micro-joint network. This analysis approach has been already conducted on a three-month long microseismic dataset collected at the Acuto field-lab, which is hosted in an abandoned quarry and is mainly exposed to environmental forcings (rainfalls and thermal cycles); moreover, to account also for anthropic vibrations, preliminary studies were carried out on a rock mass located in proximity of a railway. As a further perspective, the investigation of multi-year seismic dataset acquired on unstable rock masses will allow to better inspect the reliability of this analysis approach for rock mass damaging assessment.</p>

scholarly journals A Study of the Effects of Geological Conditions on Korean Tunnel Construction Time Using the Updated NTNU Drill and Blast Prediction Model

2021 ◽  
Vol 11 (21) ◽  
pp. 10096
Author(s):  
Yangkyun Kim ◽  
Sean Seungwon Lee
Keyword(s):  
Rock Mass ◽  
Prediction Model ◽  
Rock Properties ◽  
Design Stage ◽  
Construction Time ◽  
Tunnel Support ◽  
Advance Rate ◽  
Rock Mass Quality ◽  
Geological Conditions ◽  
Drill And Blast

This paper analyses the construction time and advance rate of a 3 km long drill and blast tunnel under various geological conditions using an upgraded NTNU drill and blast prediction model. The analysis was carried out for the five types of Korean tunnel supports according to the rock mass quality (from Type 1, meaning a very good rock mass quality; to Type 5, meaning a very poor rock mass quality). Four kinds of rock properties, as well as the rock mass quality, for each tunnel support type were applied to simulate different geological conditions based on previous studies and the NTNU model. The construction time was classified into five categories: basic, standard, gross, tunnel and total, according to the operation characteristics to more effectively analyse the time. In addition, to consider the actual geological conditions in tunnelling, the construction times for the three mixed geological cases were analysed. It was found that total construction time of a tunnel covering all the operations and site preparations with a very poor rock mass quality was more than twice that of a tunnel with a very good rock mass quality for the same tunnel length. It is thought that this study can be a useful approach to estimating the construction time and advance rate in the planning or design stage of a drill and blast tunnel.

scholarly journals PERFORMANCE PREDICTION OF HYDRAULIC BREAKERS IN EXCAVATION OF A ROCK MASS

2021 ◽  
Vol 36 (4) ◽  
pp. 107-119
Author(s):  
Mohamed Ismael ◽  
Khaled Abdelghafar ◽  
Mohamed Sholqamy ◽  
Mohamed Elkarmoty
Keyword(s):  
Rock Mass ◽  
Site Investigation ◽  
Time Frame ◽  
Rock Properties ◽  
Environmental Aspects ◽  
Rock Quality ◽  
Light Duty ◽  
Mass Properties ◽  
One Year

The demand for the usage of hydraulic rock breakers in excavating rock masses has increased recently for environmental and economic reasons. The conventional method (i.e., drill and blasting technique) has many restrictions due to environmental aspects. In this paper, we propose a methodology for the prediction of the performance of hydraulic rock breakers in the excavation of a rock mass. The case study area is located in Northwest Egypt on the shoreline of the Mediterranean Sea. Extensive site investigation was implemented using exploration boreholes showing that the majority of the site is limestone with lenses of sands. Based on the collected rock properties, mapping of both the rock quality (RQD) and the uniaxial compressive strength (UCS) for the rock mass was conducted. Such mapping of the mechanical properties helps in the zoning of a rock mass and grouping the similar rock zones of nearly matched properties. Due to economic and machinery availability concerns, this study focuses on very small, small, and medium capacity hydraulic breakers. For each type of rock breaker, calculations of the net breaking rate (NBR) are implemented for each group of the rock with similar properties. The challenge of this methodology is that the excavation of the rock mass shall be implemented in a very limited time frame (only one year ≈ 300 workdays). Therefore, two scenarios of light-duty and medium rock breakers are applied providing the number of machines required with specifications and working days. The first scenario is assigned to medium duty machines, while the second scenario concerns very small to small rock breakers. In general, such a sequence could be adopted for other cases with different rock mass properties, hydraulic breakers specifications and any desired time frame.

scholarly journals DESIGN OF DRILLING AND EXPLOSION WORKS IN UNDERGROUND MINING USING IN MICROMINE GGIS

2020 ◽  
Vol 1 (1) ◽  
pp. 3-14
Author(s):  
Andrei A. Basargin ◽  
Viktor S. Pisarev
Keyword(s):  
Rock Mass ◽  
Underground Mining ◽  
Rock Properties ◽  
Modern World ◽  
Geological Exploration ◽  
Mining Operations ◽  
Design Decisions ◽  
Well Placement ◽  
Rational Distribution ◽  
Special Software

In the modern world, an increasing number of enterprises involved in geological exploration and exploration use special software and information systems in their work. The use of such systems can significantly accelerate the processing and analysis of information. They make it possible to automate the processing and interpretation of geological exploration data, as well as use them to model deposits and design underground drilling and blasting operations. GGIS Micromine will automate the design of drilling and blasting operations while ensuring well placement taking into account the block geometry and rock properties, and a rational distribution of borehole charges for the most efficient crushing of rock mass. In conditions of high intensity of mining operations at the MGIS quarries, Micromine ensures the efficiency and multivariance of design decisions when performing blasting.

scholarly journals Smart Software Assessment of Effects of Rock Properties on Blast-Induced Ground Vibrations

2020 ◽  
Vol 9 (2) ◽  
pp. 393-397
Keyword(s):  
Rock Mass ◽  
Rock Strength ◽  
Prediction Models ◽  
Strength Properties ◽  
Rock Properties ◽  
Vibration Velocity ◽  
Rock Mass Properties ◽  
Ground Vibrations ◽  
Mass Properties ◽  
Software Assessment

The drilling and blasting method considered most economical method in civil and urban construction process. Ground vibrations are one of the major problem in blasting activity. Velocity of blast induced ground vibrations influenced by mainly three parameters such as properties of the rock mass properties, the explosive characteristics and the blast design and execution. In those parameters, rock mass properties of blasting area are unchangeable, so study of influence of rock properties very essential to minimize the effect of vibration on nearby structure. This study investigated the effect of rock strength parameters on vibration velocity. In this study, the blasting vibration monitored at a blasting site with different rock masses. This paper, presented a review on prediction models and rock properties influence on peak particle velocity. This paper also presented the relation between peak particle velocities different mines with their respective rock properties. This paper critical analysis on previous studies. This paper presented correlation between rock strength properties like compressive strength and tensile strength on vibration velocity.

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