M.A. Chamanzad; M. Nikkhah
Abstract
Drilling and blasting have numerous applications in the civil and mining engineering. Due to the two major components of rock masses, namely the intact rock matrix and the discontinuities, their behavior is a complicated process to be analyzed. The purpose of this work is to investigate the effects of ...
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Drilling and blasting have numerous applications in the civil and mining engineering. Due to the two major components of rock masses, namely the intact rock matrix and the discontinuities, their behavior is a complicated process to be analyzed. The purpose of this work is to investigate the effects of the geomechanical and geometrical parameters of rock and discontinuities on the rock mass blasting using the UDEC software. To this end, a 2D distinct element code (DEM) code is used to simulate the stress distribution around three blast holes in some points and propagation of the radial cracks caused by blasting. The critical parameters analyzed for this aim include the normal stiffness (JKN) and shear stiffness (JKS), spacing, angle and persistence of joint, shear and bulk modulus, density of rock, and borehole spacing. The results obtained show that the joint parameters and rock modulus have very significant effects, while the rock density has less a effect on the rock mass blasting. Also the stress level has a direct relationship with JKN, JKS, bulk modulus, and the shear modulus has an inverse relationship with the rock density. Moreover, the stress variation in terms of spacing and joint angle indicates sinusoidal and repetitive changes with the place of target point with respect to the blast hole and joint set. Also with a decrease in the JKN and JKS values, the radial cracked and plastic zones around a blast hole show more development. With increase in the joint persistence, the plastic zones decrease around a blast hole.
Rock Mechanics
A. Turanboy; E. Ülker; C. B. Küçüksütçü
Abstract
The intersection lines between discontinuity surfaces and their intersection points on the visible surfaces of any engineering structure may be the instability indicators. This paper describes a new approach to modelling the intersecting lines and points that would provide the first evaluation of any ...
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The intersection lines between discontinuity surfaces and their intersection points on the visible surfaces of any engineering structure may be the instability indicators. This paper describes a new approach to modelling the intersecting lines and points that would provide the first evaluation of any instability in an engineering structure characterized by the failure modes. In this work, the intersection lines were grouped according to their direction either in the reverse or in the same direction as the dip of the slope. Furthermore, the intersection lines are grouped according to various ranges of the interior friction angle, which can be selected by the users in a computer application developed for this work. The orientation of the intersecting lines and the location of the exposed intersection points are defined and assigned as the scatter points. These exposed points are clustered to determine the centroid locations. The K-means clustering is used in this step. Finally, all these analyses are integrated in a logical order, and the results obtained are used to assess the instabilities on the slope surface. Experiments are carried out on a rock cut along the Konya-Antalya (Turkey) highway, which is composed of limestone, to demonstrate the performance and results of the approach. The locations of the possible failure zones in the critical range of the interior friction angle are defined both visually and numerically along the slope. Experiments show that the proposed method is very useful and easy to implement and yields practical preliminary evaluation results pertaining to instabilities according to the basic failure modes.
M Ebadi; Saeed Karimi Nasab; H Jalalifar
Abstract
rnDetermination of rock mass deformation modulus is very important in different projects, especially in civil and mining engineering works. In-situ measurements such as dilatometer, plate load and flat jack methods may be applied to determine the deformation modulus. However, these methods are very expensive ...
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rnDetermination of rock mass deformation modulus is very important in different projects, especially in civil and mining engineering works. In-situ measurements such as dilatometer, plate load and flat jack methods may be applied to determine the deformation modulus. However, these methods are very expensive and time- consuming. Analytical methods are very useful approaches which can also be used to estimate rock mass deformation modulus. Using these methods, the parameters influencing the rock mass modulus can also be evaluated. Analytical methods are based on the resultant displacement of rock mass and joints which are finally used to predict the rock modulus. It should be mentioned that none of the available analytical models could present a model to consider the effect of lateral stresses on rock mass modulus calculations. Therefore, this paper tries to investigate the effect of intermediate principal stress (σ2) and minimum principal stress (σ3) on the deformation modulus of jointed rock mass.rn
