Exploration and Mining
Yaghoob Zarei; Ali Uromeihy; MohammadReza Nikoodel
Abstract
In this labratory study, the effect of joint density (number and spacing) on the pressure wave velocity was researched in pyroclastic rocks. After determining the physical properties, the P-wave velocities of intact rock samples were measrued. Then, an artificial joint perpendicular to the measuring ...
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In this labratory study, the effect of joint density (number and spacing) on the pressure wave velocity was researched in pyroclastic rocks. After determining the physical properties, the P-wave velocities of intact rock samples were measrued. Then, an artificial joint perpendicular to the measuring direction was created in each sample, and the wave velocity tests were repeated. These tests were continued up to 5 joints with two sets of 2 and 5 cm spacing. Consequently, the data were analyzed using the statistical methods. The results show that the P-wave velocity was decreased by increasing the number of joints in both spacing sets, and thus an inverse linear relationship was obtained. However, as the number of joints increases, the reduction rates of wave velocity were different at two spacing sets. More precisely, up to 3 joints, the reduction rate in the 5 cm spacing set was more than that in the other set. Nonetheles, after the third joint, the decreasing rate in the 2 cm spacing set became greater. Generally, the shorter spacing had a more reduction (attenuation) in the P-wave velocity. In this regard, at a total of 5 joints, the reduction rate of the P-wave velocity in 2 cm spacing set was more than that in the other set.
Mohammad Masoud Samieinejad; Navid Hosseini Alaee; Kaveh Ahangari
Abstract
Because of the important role of rock mass structural properties on its mechanical behavior, determining the qualitative and quantitative properties of has been a subject of intense research. In this regard, numerous techniques such as scanline surveying, cell mapping, and geologic structure mapping ...
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Because of the important role of rock mass structural properties on its mechanical behavior, determining the qualitative and quantitative properties of has been a subject of intense research. In this regard, numerous techniques such as scanline surveying, cell mapping, and geologic structure mapping have been proposed. However, applying such field surveying techniques for rock mass properties involves spending substantial costs and times and high risks. Besides, due to the errors induced by operations, measurements, systematic errors, etc., the results of these techniques are not accurate and precise enough. Short-range digital photogrammetry is an state-of-art technique applied for surveying rock mass characteristics. Through this novel approach, rock mass surface is imaged, the obtained images are analyzed, and rock mass characteristics are determined, and finally, the technique is validated by comparing the obtained results with field surveys. In the present work, two digital photogrammetry based methods including digital image processing and laser-based imaging are implemented in rock mass characterization. The results show that short-range digital photogrammetry can be effectively employed in rock mass structure characterization. Moreover, this approach, unlike the existing traditional ones, involves low costs, high speed, and sufficiently accurate and precise results.
S. H. Hoseinie; H. Aghababaei; Y. Pourrahimian
Abstract
Drilling is one of the most expensive stages of open pit mining and has more complexity. In drilling process many parameters influence simultaneously, where studying each parameter requires recognition of the effects of the characteristics of the rock mass and its material. In ...
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Drilling is one of the most expensive stages of open pit mining and has more complexity. In drilling process many parameters influence simultaneously, where studying each parameter requires recognition of the effects of the characteristics of the rock mass and its material. In this paper, the main aim was directed to investigate the joints dipping among the structural parameters of the rock mass. In the course of study, geometrical condition of penetration and transition of drill bit from joint surface were analyzed and different conditions of dips considered mathematically. This was followed by physical modeling of each of the geometrical conditions and penetration rate of cross bit measured by using rotary drilling system. Based on the numerical results obtained from experiments, mathematical equation between angles of joint dip with respect to drilling prolongation and penetration rates was presented. Furthermore, in conformity with the presented equation, by decreasing relative angle of joints dip, penetration rate of drill bit in jointed rock masses decreases linearly.
