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| 3. |
- Weston, Richard, et al.
(author)
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Finite element models for use in mechanics including geological engineering
- 1998
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In: Engineering Geology. - 0013-7952. ; 49:3-4, s. 363-369
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Journal article (peer-reviewed)abstract
- A number of finite element (FE) models have been developed, starting with a purely magnetic one. The magnetic model was verified against analytical solutions and the commercial FE-programme ANSYS. The magnetic model was then coupled to the wave-equation, resulting in a model governing linear magnetostriction. In the magnetostrictive model a property of two degrees of freedom, that is, displacements, was coupled to a property of one degree of freedom, that is, magnetic potential. To make this possible, non-quadratic coupling matrices had to be developed. This linear model was then verified against analytical solutions, with a good conceptual agreement. In the next step the still linear system of equations was time-propagated, using the Newmark method. This model was verified by comparing the differential step-response of the system calculated with the time propagation method, to the frequency function of the system, calculated with the harmonic model. Further, non-linear and non-linear transient models were developed and discussed. The non-linear transient model was developed for a situation where a Terfenol rod was assumed to collide periodically with a rigid wall, thus indicating a tool for analysing a Terfenol based resonant system, which could be used, for example, for ultrasonic cutting of hard and brittle materials and also for rock-blasting.
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| 4. |
- Börgesson, Lennart
(author)
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Water flow and swelling pressure in non-saturated bentonite-based clay barriers
- 1985
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In: Engineering Geology. - : Elsevier BV. - 0013-7952 .- 1872-6917. ; 21:3-4, s. 229-237
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Journal article (peer-reviewed)abstract
- The water uptake of 10 and 20% bentonite-sand mixtures and of 100% pure bentonite was studied experimentally. The results were compared with calculated water content distributions to study the usefulness of the diffusion equation. The relation between the swelling pressure and the degree of saturation of a bentonite was also studied.
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| 5. |
- Eriksen, Trygve, et al.
(author)
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Sorption effects on cation diffusion in compacted bentonite
- 1999
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In: Engineering Geology. - 0013-7952 .- 1872-6917. ; 54:1-2, s. 231-236
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Journal article (peer-reviewed)abstract
- Diffusion of Na+. Cs+, Co2+ and Sr2+ in bentonite compacted to a dry density of 1800 kg m(-3) and saturated with groundwaters and aqueous solutions of differing ionic strength have been studied experimentally using the through diffusion technique. Sorption experiments have been carried out under a wide range of pH and concentration of supporting electrolyte. The dependence of the apparent diffusivity of Na+, Cs+ and Sr2+, mainly sorbed by ion exchange, on the sorption intensity is accommodated by a model encompassing diffusion of the sorbed cations within the electrical double layer next to the mineral surface in addition to diffusion in the pore water. The apparent diffusivity of Co2+, sorbed by surface complexation reactions, corresponds to complete immobilization on sorption.
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| 6. |
- Feng, Q., et al.
(author)
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Measuring fracture orientation at exposed rock faces by using a non-reflector total station
- 2001
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In: Engineering Geology. - 0013-7952 .- 1872-6917. ; 59:1-2, s. 133-146
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Journal article (peer-reviewed)abstract
- Measurements of fracture orientation are usually taken by using a compass-inclinometer device on exposed rock faces. The drawbacks when using this method is that it is time-consuming if many fractures are measured and that measurement might be impossible if the rock face cannot be safely reached physically. To improve field mapping of rock fractures, a method for applying a non-reflector total station to measuring fracture orientation is presented in this paper. A non-reflector total station is a geodetic device that captures three-dimensional co-ordinates of target points without using a reflector. Therefore, physical touching the rock surfaces is no longer required. To determine a fracture orientation, co-ordinates of a set of points on the exposed fracture surface are captured at a distance from the rock face. The best-fit plane of the exposed fracture surface is defined by the co-ordinates of the target points, and the orientation (e.g. dip angle and dip direction) of the fracture surface is determined as that of its best-fit plane. This paper presents the technical procedure and a portable system designed for the field mapping of fracture orientation. Results of a case study performed at an exposed rock face are also included.
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| 7. |
- Huang, Yi, et al.
(author)
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Introduction of neural network system and its applications in rock engineering
- 1998
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In: Engineering Geology. - 0013-7952 .- 1872-6917. ; 49:3-4, s. 253-260
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Journal article (peer-reviewed)abstract
- Neural network systems have a great advantage in dealing with problems in which many factors influence the process and result, and the understanding of this process is poor, and there are experimental data or field data. Most of the these problems occur in rock engineering. This article provides a brief introduction to neural network systems. Problems such as what is a neural network, how it works and what kind of advantages it has are discussed. Several applications in rock engineering are also detailed
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| 8. |
- Kou, Shao-Quan, et al.
(author)
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Identification of the governing parameters related to rock indentation depth by using similarity analysis
- 1998
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In: Engineering Geology. - 0013-7952 .- 1872-6917. ; 49:3, s. 261-269
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Journal article (peer-reviewed)abstract
- This paper focuses on the indentation depth in rocks caused by a hemispherical indenter. The problem is approached by a combination of similarity methods with an artificial neural network. The similarity methods offer a profound understanding of the physical problem and help to identify the most important governing parameters or factors that reflect the essence of the rock indentation events, thus simplifying the target problem. The artificial neural network provides an advanced computing model, which allows more factors to be involved. The predictions obtained using this combined approach are in better agreement with the experimental results than predictions using other methods.
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| 9. |
- Kulatilake, Pinnaduwa H.S.W., et al.
(author)
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Analysis of structural homogeneity of rock masses
- 1990
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In: Engineering Geology. - 0013-7952 .- 1872-6917. ; 29:3, s. 195-211
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Journal article (peer-reviewed)abstract
- The statistical tests suggested by Miller (1983) and Mahtab and Yegulalp (1984) to investigate structural homogeneity in rock masses are reviewed. The difficulty in making a decision about statistical homogeneity only through the results of either one of these two tests or through equal-area polar plots, is shown through a case study. New interpretations are suggested for these two tests to use them in assigning relative ranks for the strength of homogeneity of different regions in rock masses. An example is given to illustrate how one can use Miller's method with new interpretations along with equal-area plots in making decisions about statistical homogeneity in rock masses. The example also shows an attempt to incorporate results of Mahtab and Yegulalp's test with new interpretations to the decision-making process
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| 10. |
- Li, Chunlin, et al.
(author)
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Stress-strain behaviour of rock material related to fracture under compression
- 1998
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In: Engineering Geology. - 0013-7952 .- 1872-6917. ; 49:3/4, s. 293-302
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Journal article (peer-reviewed)abstract
- Fracture is the main reason for the non-linear behaviour of hard rocks. The fracture mechanics of rock is studied in this article by analysis of the fracture process under compression. A constitutive model that describes the relationship between the macro deformation of rock and the micro fracture within rock is developed. The propagation of microcracks, the non-linearity of deformation, the loading-and-unloading hysteresis and the variation of the apparent Young's modulus and Poisson's ratio are studied using the developed model. The model simulations demonstrate that: (1) the fracture toughness, initial crack length, crack density, and Young's modulus are four crucially important parameters that affect the deformation behaviour of rock; (2) the elastic parameters (E and v) of the rock matrix should be measured in triaxial tests. If they are measured in uniaxial tests, the upper straight unloading portion of the stress-strain curve is suggested to be used for the purpose, unless the closure effect of open cracks will be included in the estimations. In addition (3), the slope of the reloading stress-strain curve is a measure of the damage in material.
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