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Collaborating Authors
2nd North American Rock Mechanics Symposium
ABSTRACT A natural joint wall surface is an irregular rough non planar surface. The non planar surface consists of an heterogeneous distribution of asperities with various sizes and shapes over a flat smooth surface. Is the shear behavior dependent on the joint wall morphology? In order to give an answer to this question, we describe, analyze and compare joint wall morphology of sheared joints that were strictly identical before testing. Identical replicas of a natural fracture in a granite were molded from an original sample and shearing tests were performed under various normal stresses and stopped at defined shear displacements. During shear testing shear displacement rate was constant and the joint mean plane was kept horizontal. The analysis of the morphology of the joint wall sheared surface consists in the identification of the damaged areas using an image analyzer. The evolution of the size and location of the damaged areas are analyzed in relation with the normal stress for a given shear displacement. 1 INTRODUCTION Literature on rock joint mechanical behavior and their applications to various workings stability analysis is quite abundant over the last fifteen years; testing and modeling of rock joints become more and more important (Stephanson & Jing, 1995). Few works have been dedicated to the progressive degradation of the joint surface morphology during shear displacement and its influence on stress-strain-dilatancy. These mechanical parameters characterizing rock joint behavior depend on the contact areas between the joint walls, their morphology and the magnitude of the normal stress acting on them. The knowledge of the evolution of the joint wall morphology is a prerequisite to estimate and evaluate the parameters that we need for modeling their mechanical behavior. Thus this paper is a contribution to the characterization of damaged zones created during shearing experiments with various normal stress and shear displacements. This characterization is based on the acquisition of grey level images of the joints surfaces; after that, a region based segmentation enables to identify the damaged zones and to generate binary images. Finally measurements of geometrical characteristics of the damaged zones are performed. 2 EXPERIMENTAL TESTING2.1 The replicas A series of identical replicas of a natural fracture in a granite (Guéret, France) was realized using a cement mortar. The original sample of the fracture from which replicas were molded was drilled perpendicular to the fracture plane. The upper parts of the replicas were grey dyed while the lower parts were stained pink (Figure 1). Then, each part of the replicas was adjusted carefully in a steel box, to ensure their mutual position and orientation. The method of fabrication allows to create a great number of replicas so it is possible to perform shearing experiments keeping constant some parameters and varying the others. In this paper we present the evolution of the degradation of the joint surface morphology when increasing both the normal stress and the shear displacement, the rate of shearing and the direction of shearing remaining unchanged.
- Europe > France (0.35)
- North America > Canada (0.28)
1. INTRODUCTION
ABSTRACT :
We conducted two series of hydraulic fracturing experiments. In one we maintained unequal principal horizontal far-field stresses; in the other the horizontal stresses were isotropic. Tested boreholes were instrumented with a device capable of monitoring diametral changes during pressurization in two perpendicular directions. During borehole pressurization under anisotropic far-field stresses diametral increase at right angles to the future hydrofrac helped isolate two critical pressures, one at which fracture initiated (well before breakdown) and one at which fracture propagation stopped (beyond breakdown). Under isotropic far-field stress fracture initiation appeared to coincide with breakdown. Both results are in accord with a recent fracture mechanics analysis of hydraulic fracture mechanism. The ability to detect the fracture initiation pressure in the field is a prerequisite to obtaining more accurate estimates of the maximum in situ horizontal stress using conventional hydrofrac criteria.
The conventional interpretation of the hydraulic fracturing process has been that the breakdown pressure Pb, the peak pressure reached during pressurization of the borehole test interval, signifies the instance of hydrofrac initiation. The magnitude of the pressure at which fracture initiates is crucial to the accurate assessment of the maximum horizontal stress H based on the elastic (Hubbert and Willis, 1957) or the poroelastic (Haimson and Fairhurst, 1967) approaches. Both of these criteria assume linear elastic behavior of the rock until tensile failure occurs and fracture initiates. Recently, Detournay and Carbonell (1994) have challenged the assumption that hydraulic fractures necessarily initiate at Pb. They distinguish between three different critical pressures: one responsible for fracture initiation (P1), another for unstable fracture propagation (P11), and the breakdown (peak) pressure (Pb). They speculate that the condition of unstable fracture propagation, defined as the state of continued crack propagation under decreasing test interval pressure, is in effect equal to the breakdown pressure, i.e. P11 = Pb. Furthermore, using a fracture mechanics approach, they define P1 as the pressure at which a critically oriented pre-existing natural short crack around the borehole is in a state of limit equilibrium. They deduce that at slow pressurization rates and uniform far-field stress (sh = sH) fracture propagation at initiation is always unstable. Thus, initiation pressure in this case is also the breakdown pressure (P1 = Pb), as assumed in the conventional elastic and poroelastic hydrofrac criteria. On the other hand, when the two horizontal far-field stresses are non-isotropic (sh
- Geology > Geological Subdiscipline > Geomechanics (1.00)
- Geology > Rock Type > Igneous Rock > Granite (0.44)
Contaminant Transport In Fractured Porous Formations With Strongly Heterogeneous Matrix Properties
Jansen, D. (Institute of Hydraulic Engineering and Water Resources Management, Aachen University of Technology) | Kongeter, J. (Institute of Hydraulic Engineering and Water Resources Management, Aachen University of Technology) | Birkholzer, J. (Lawrence Berkeley Laboratory, Earth Science Division)
ABSTRACT: Contaminant transport in fractured porous formations is often simulated with dual-porosity models. In such models the heterogeneous formation is separated into two coupled continua, one representing the fractures, one representing the rock matrix. The main objective of the present study is to investigate the effect of spatial variations of matrix block properties (especially such as size and shape) and to determine effective continuum parameters for the matrix continuum. Different averaging approaches are compared with regard to their suitability for continuum representation of the matrix system. A numerical study was performed considering two different sets of simulation runs. One considering the exact matrix properties, and the second using different averaged effective continuum parameters. The breakthrough curves are compared to check the accuracy of the averaging procedures with regard to their application in dual-porosity models. 1 INTRODUCTION Fractured porous formations are typified by a high permeable fracture system and a matrix system with very low permeability but high storativity. Due to the different response times in the fractures and in the matrix regional transport takes place in the fractures and is of advective-dispersive character. Transport in the matrix blocks is of diffusive type; it depends on the concentration in the adjacent fractures and is therefore of local nature. Contaminant transport in such systems is often simulated with dual-porosity models. Essential to the principle on homogenization for heterogeneous media is the definition of equivalent model parameters for both media, capable of describing the correct physical behavior of the system. Numerous studies have been performed e.g. by (Long et al. 1982, 1987) in the past to check if a continuum representation of fracture networks is valid. If so equivalent continuum parameters can be derived and the model error associated to this averaging process may be estimated. However, only little work has been done to address this task with regard to the matrix blocks of a given subdomain, which may considerably vary in size, shape or material properties. In most cases of dual-porosity modelling, the matrix continuum parameters are only roughly estimated and error analysis is not performed. Due to the distribution of the fractures the geometric parameters (block size and shape) can be extremely heterogeneous in the matrix system. These heterogeneities are important for the transport behavior of the matrix system. 2 APPROACH For continuum representation of heterogeneous rock formations (e.g. dual-porosity models) averaging procedures for the fracture system as well as for the matrix system are necessary. In many studies the equivalent continuum parameters of fracture systems are derived by determining the heterogeneous behavior of the system using discrete models (discrete representation of the fractures). The accurate description of the matrix volume and cross- section area available for matrix diffusion at a certain distance from the matrix-fracture interface is essential to the correct simulation of matrix diffusion. However, in most of the case studies concerning dual-porosity models the matrix system has been strongly idealized to a set of matrix blocks uniform size and shape and detailed averaging procedures have not been applied.
1 INTRODUCTION ABSTRACT: Research on damage process in the region of low confinement near openings, subjected to high in-situ stresses, suggests that it initiates in a moderately jointed brittle rockmass by the nucleation and growth of extension fractures within the intact rock material inside the rockmass, and that valid information can be extracted from laboratory tests on intact rock to assess the initiation of rockmass damage (Castro, 1996). This papers proposes that potential zones of damage initiation (DI) around deep excavations can be reliably predicted by performing elastic numerical analyses to identify regions where the deviatoric stress, (s1-s3), exceeds the threshold value at which stable crack growth commences for intact rock tested under uniaxial compression, s sc. Application of this criterion, successfully predicted the depth of the DI zones in the moderately jointed, brittle norite rockmass surrounding the Sudbury Neutrino Observatory (23 m diameter x 30.8 m high) excavated at a depth of 2070 m at INCO's Creighton Mine in Sudbury, Canada. Field observations and an extensive literature review strongly suggests that, under compressive loading and conditions of low confinement, the damage process is dominated by the initiation and propagation of extension fractures within the intact rock. This means that the mode of damage initiation is by extension fracturing, which was observed to: a) nucleate, at a microscopic scale, from stress concentrators such as pores, pre-existing cracks and particularly, grain boundaries in most polycrystalline rocks; b) be a consequence of induced (or local) tensile stress, extension strain, or strain energy density around these stress concentrators; c) form at low angle (i.e.,<10º) or parallel to the direction of the major principal induced stress; and d) be sensitive to changes in the magnitude and direction of the major principal stress (Castro, 1996). Research on damage and failure processes in the region of low confinement near openings, subjected to high in-situ stresses, suggests that movements of blocks and along pre-existing, non-continuous discontinuities have only a minor effect on rockmass damage initiation, because the blocks do not have the kinematic freedom to allow translation or rotation. Thus, damage must initiate and progress within intact rock material. However, the progression of the damage process then creates new internal structures. The interaction of the newly formed internal fractures, together with the pre-existing discontinuities, increases the number and variety of kinematically feasible failure mechanisms that can be developed around the opening (Castro, 1996). This paper proposes that, even in a moderately jointed rockmass, the onset of damage is essentially controlled by the inherent properties of the intact rock material inside the rockmass and their relationship to the magnitude and orientation of the induced deviatoric stresses. If this hypothesis is correct, it means that valid information can be extracted from small-scale laboratory tests regarding the onset of damage, which occurs in a moderately jointed rockmass around an underground excavation at great depth, i.e., information can be transferred between different loading systems, the laboratory system and the field system, respectively.
ABSTRACT: An experimental study was conducted to investigate the surface characteristics of an oil sand fracture and its mechanical response to an increasing confining pressure. The oil sand fracture was induced in core samples along the axis of the sample using the Brazilian tension test. A Computer Assisted Tomography (CAT) scanning analysis was performed before and during the application of confining pressure to determine the fracture geometry during the closure process. The fracture was shown to be a variable aperture system with (when considering possible fluid conductance) surface roughness and tortuosity becoming increasingly important as the fracture closed. The mechanical response showed the importance of surface roughness and the resultant contact area on the ability of the fracture to withstand a confining pressure. 1 INTRODUCTION Heavy oil and bitumen are a major energy resource in Canada, Venezuela, and elsewhere. The challenge in developing this resource is the difficulty in recovering these highly viscous substances. Thermal recovery has become an accepted method with steam-based recovery drawing much attention. Steam-based recovery methods involve the injection of steam into the reservoir to heat up the reservoir, lowering the viscosity of the bitumen, which increases production rates. Cyclic steam- based recovery processes have become common practice in the thermal operations of the Cold Lake heavy oil reservoirs (Boone et al. 1993). The steam injection approach used at Cold Lake encourages fracturing of the reservoir each steam cycle, exploiting the permeability of the fracture instead of relying on a layer of bitumen depleted, permeable oil sand. The high hydraulic conductivity of the fracture enables heat transfer to take place further away from the well, thus, accessing more undisturbed reservoir material instead of depositing most of the heat in a previously heated and bitumen depleted area of the reservoir. In order to optimize this steaming approach an understanding of the medium used to carry the heating agent, the fracture, is essential. The geometry of the fracture, characterized by surface roughness, aperture distribution and tortuosity, plays a key role in the permeability of the fracture as well as the flow channels available to the injected mass. A detailed picture of an oil sand fracture, its surface characteristics and mechanical behaviour under a varying confining pressure is needed to better understand and possibly exploit the flow phenomena taking place during and after the hydraulic fracturing process of steam stimulation. According to the authors knowledge, no work is currently available characterizing an oil sand fracture or proving that fractures in this material behave in a similar manner as to what has been previously studied in rock fractures (Barton et al. 1985; Brown and Olsson 1993; Hakami and Barton 1990). The following study presents an experimental, physical characterization of an oil sand fracture using a Computer-Assisted Tomography (CAT or CT) scanning analysis to visualize the fracture geometry and closure response. The results of this procedure give an understanding of an oil sand fracture's aperture distribution, surface roughness, as well as its mechanical behaviour under an increasing confining pressure.
ABSTRACT : Artificial neural networks were used to infer missing data when given geological data were insufficient. But the learning of the traditional networks were too slow for practical use. Authors adopted Fahlman's quickprop program to accelerated artificial neural network, to improve learning ability and speed up the learning time. Some test result showed learning time of new networks was reduced from tens of hours to a few minutes, while the output pattern was almost the same with other studies when the program ran on IBM compatible PC486 DX 66 MHz machine. Cecil's database was used for learning pattern. All the test run showed sufficient accuracy. 1. INTRODUCTION Accurate and resonable rock mass classification is needed to design and construct underground rock structures safely and economically. Rock classification methods are empirical ones to classify the rock mass and determine the support amounts by the ratings. Many items are needed like RQD, weathering condition of discontinuities, to classify the rock mass properly. Geological data sets can be usually insufficient in early stage of design because there are many limitations to reach underground site or uncertainty of the property itself. Traditional classification algorithms cannot work when one or more data items are omitted. Even all the data item is given, there can be a confliction between the data. In this case engineer must do some guesswork and inevitably be biased. Artificial intelligence like fuzzy system, expert system or artificial neural networks can be used to diminish the subjective errors. Neural networks are simplified models of neurons. They are composed of nodes in input, hidden and output layers and their connections. They learn facts from the given database through activation function and by controlling connection weights to make generalized inner information. They infer wanted data from new data set which they didn't learn or omitted or from distorted data set which they learned. There are more than 50 neural network models and many of them adopted error back propagation (EBP) learning algorithm with the generalized delta rule by Rumelhart et al.(1986) Some neural networks have been introduced in rock engineering field. Among them are networks to predict elastic compressibility of sandstone specimens (Zahng et al, 1991) and to infer failure mode of rock mass (Lee and Sterling, 1992). Conventional artificial neural networks require exceedingly long learning time. This disadvantage lead to lack of efficiency. They are too slow for practical use. In this study, authors take up new algorithms of accelerated artificial neural network, to improve learning speed and ability of artificial intelligent program. Adopted algorithm is Fahlman's quickprop program (Fahlman, 1989). It is modified and made to a module of ROMES, Rock Mechanics Expert System (Yang et al., 1995). New program was tested by well known XOR and character recognition problems to verify the validity. It was applied to the reference data of Cecil and others which were applied by Lee and Sterling, and Moon and Lee (1993). The inferred results, learning speed and ability were compared with those others.
ABSTRACT: In order to examine the influence of the water as stress corrosion agent on the strength of rocks, a series of uniaxial compression tests under the water vapor pressure ranging from 10 to 10 Pa is conducted on Kitagishima granite and Kumamoto andesite. The values of the stress corrosion index of both rocks are determined. 1 INTRODUCTION At the beginning of the twenty one century, the large rock cavern for radioactive waste disposal will be constructed within a rock mass at a depth of more than 1000m, in Japan. The stability of such large rock cavern must be guarantee over very long timescale. The prediction of long-term strength of rocks is indispensable for insuring long-term stability of the rock cavern. The strength of rocks under compression is affected by the density, the shape and the direction of cracks, the strain and stress rate of loading, the stress state, the temperature and the existence of water in vapor phase or in liquid phase, and so on. Some researchers have indicated that the strength of rocks is dependent on the subcritical crack growth due to stress corrosion and is proportional to the water vapor pressure in atmosphere. However, few experiments to verify this fact have been performed. In this paper, to examine the influence of the water as the stress corrosion agent on the strength of rocks, a series of uniaxial compression tests under the water vapor pressure ranging from 10-³ to 10³ Pa is conducted on Kitagishima granite and Kumamoto andesite. Furthermore, the stress corrosion index is determined, then the estimation of long-term strength of rock is discussed. 2 RELATION BETWEEN STRENGTH AND WATER VAPOR PRESSURE In general, it is considered that the stress corrosion plays a major role in the subcritical crack growth at the fracture of rocks, ceramics. The water, namely aqueous environments, is one of important agents for the stress corrosion of rocks. The expressions of crack velocity including the effect of the stress corrosion have been proposed to explain the subcritical crack growth, where a is the crack length, p is the water vapor pressure, E* is the activation energy, k is the Boltzman's constant, T is absolute temperature, nw and n are experimentally determined constants and E* is the tensile stress near the crack tip for a very narrow elliptical crack. The value of nw is to be almost unity (Wiederhorn 1969). Sano performed a series of the experiments in which the strain rate varied under atmosphere, then the stress corrosion index of Oshima granite was determined to be 32. The values of stress corrosion index of other rocks is determined by John (1972), Sangha (1972), and Peng (1973) based on uniaxial compressive strength obtained from the same testing method. These values were 32 to 62. The values of the stress corrosion index determined by them were 13 to 70. However, there is a few experiments to examine the influence of the water vapor pressure on the uniaxial compressive strength.
- Geology > Rock Type > Igneous Rock > Granite (0.71)
- Geology > Geological Subdiscipline > Geomechanics (0.70)
ABSTRACT: In testing rock specimens containing a single discontinuity, both the direct shear test and the triaxial compression test may be used to determine the strength and deformability characteristics of the discontinuity. However, in employing these two techniques, various investigators have indicated that there appears to be a discrepancy between the respective experimental results. In an attempt to investigate this disparity, a series of laboratory experiments were conducted using both the direct shear test and the triaxial compression test, to compare the shear strength characteristics of Penrith sandstone (PrS) and an artificial rock -like specimen (Quickrock or Qu) containing different types of a single discontinuity. 1 INTRODUCTION Before embarking on experimental results of this research, it is worth emphasizing the importance of this work with an example. Consider a cylindrical specimen containing a discontinuity that is cored from an underground rock formation. Due to the difficulties in preparing the specimen for triaxial compressive test to determine the shear strength of the joint, it is expected that the direct shear method should be used. The question is whether the latter method satisfies the condition from which the specimen has been sampled and to what extend the determined shear strength is the same as the one that exists in triaxial environment such as the underground opening. To offer an answer to these questions, one should find out whether it is possible to use triaxial and direct shear testing methods interchangeably. Consequently the comparison of results from triaxial and direct shear tests is an issue of significance. The experiments were conducted in order to assess the extend to which the direct shear tests would produce the same results with the triaxial tests when applying equivalent loading conditions. Use was made of a special triaxial cell, a detail description of which may be found in the work by BUZDAR (1968). The confining pressures employed for the triaxial tests ranged between 2.5 MPa and 15 MPa and were applied by a pressure intensifier apparatus that monitors during testing the volumetric changes with a resolution better than 0.1 ml. During the triaxial compression tests the rate of the axial strain was maintained constant at 0.25%/min. The direct shear tests were conducted in a special shear test apparatus capable of applying a maximum 1 MN normal load resulting in normal and shear stresses up to 50 MPa and 35 MPa, respectively (GHAROUNINIK, 1993). Quickrock was used as casting material for the direct shear apparatus, mainly because of its ability to gain strength at a fast rate (its uniaxial compressive strength after a few hours reaches 30 MPa and after a day is more than 50 MPa). 2 EXPERIMENTAL RESULTS In order to involve all the possible forms of discontinuities, various types of roughness in clean and infilled surfaces have been used. In other words, an attempt has been made in this study to simulate the surfaces from the simplest to the most cumbersome situation, i.e. clean smooth and infilled rough surfaces, respectively.
- Geology > Geological Subdiscipline > Geomechanics (0.56)
- Geology > Rock Type > Sedimentary Rock (0.34)
ABSTRACT: This paper presents several methods for determining the deformability, tensile strength, and fracture toughness of anisotropic rocks by diametral compression (Brazilian loading) of thin discs of rocks. The mechanical and fracture properties of several sandstones and one shale were successfully determined using the proposed methods. The deformability and tensile strength were calculated using the complex variable function method combined with the Generalized Reduced Gradient approach. The mixed-mode fracture toughness was evaluated using a new formulation of the Boundary Element Method (BEM) developed by the authors. 1 INTRODUCTION Many rocks exposed near the Earth's surface show well defined fabric elements in the form of bedding, stratification, layering, foliation, fissuring or jointing. In general, these rocks have properties (physical, dynamic, thermal, mechanical, hydraulic) that vary with direction and are said to be inherently anisotropic. Anisotropy can be found at different scales in a rock mass ranging from intact specimens to an entire rock mass. Anisotropy is a characteristic of intact foliated metamorphic rocks (slates, gneisses, phyllites, schists) and intact laminated, stratified or bedded sedimentary rocks (shales, sandstones, siltstones, limestones, coal, etc..). At a larger scale, rock mass anisotropy is found in volcanic formations (basalt, tuff), in sedimentary formations consisting of alternating layers or beds of different rock types, and in rock formations cut by one or several regularly spaced joint sets. Anisotropy plays a crucial role in various rock engineering activities. In civil and mining engineering, rock anisotropy controls the stability of underground excavations, surface excavations, and foundations. Rock anisotropy affects drilling, blasting, and rock cutting. In petroleum engineering, rock anisotropy is a critical factor in controlling borehole deviation, stability, deformation and failure. It also impacts fracturing and fracture propagation. Despite its noted importance, rock anisotropy is still poorly understood in particular by the practice. Questions that often arise include: (1) How to characterize rock anisotropy in the laboratory and in- situ? (2) When is rock anisotropy important? and (3) How much of an error is involved in neglecting rock anisotropy by assuming the rock to be isotropic ? This paper does not attempt to answer all those questions. It presents experimental and analytical methods for determining in the laboratory the deformability, tensile strength and fracture properties of intact rocks that are transversely isotropic (i.e. with one dominant direction of planar anisotropy). The methods are used in the interpretation of diametral loading tests of discs of rocks (Brazilian tests). Discs of four different types of clearly bedded sandstones and one shale were tested under diametral loading in the laboratory. The rock elastic properties were determined by measuring strains using 45° strain rosettes glued at the center of the discs. The effect of rock anisotropy on tensile strength was determined by testing several discs with planes of anisotropy inclined at different angles to the loading direction. Tests were also carried out on initially cracked discs of one sandstone and one shale in order to determine the fracture toughness under pure mode I and mode II loading.
- Geology > Geological Subdiscipline > Geomechanics (1.00)
- Geology > Rock Type > Sedimentary Rock > Clastic Rock > Sandstone (0.90)
- Geology > Rock Type > Sedimentary Rock > Clastic Rock > Mudrock > Shale (0.87)
ABSTRACT: The thirty years old history of underground nuclear tests gives a possibility to accumulate the sufficient amount of experimental data from instrumental and visual observations, which one can use to understand the influence of rock structure on excavation's stability. The analysis of results, received from investigations of the deformation and destruction processes in the close-in zone of underground nuclear explosions, is presented. It was shown, that the principle mechanism of failure of underground openings over important for practice dynamic loading amplitude range is the roof and wall breakage due to the fall of key blocks. The rock massif properties change exclusively due to relative displacements of individual rock blocks. Some empirical relations for estimations of failure extent were derived. INTRODUCTION Most of the criteria of underground excavation stability applied to rock mechanics is based on the analysis of static and dynamic stresses acting in vicinity of opening as well as on comparison of stress level with shear, tensile and compressive strength limits of rock material. It should be readily apparent that the exceeding of the strength limits actually results in failure of material near the opening, however, it does not necessary bring to the large destruction of the excavation. The indispensable condition of excavation failure (here we ignore the falling of separate small blocks and thin rock layers) is apparently to be the achievement of some level of strain at which the significant volume of rock near the opening loses the stability or, in other words, become movable. In the rock massif divided into the blocks by the joints and faults of different scales the problem of providing the underground dynamic excavation stability cannot be properly solved on the basis of the traditional solution of mechanics of continua. Any engineering methods of providing stability and usually designed for averaged spaced stress may appear to be useless due to very large values of the discrete local rock loads acting on opening support even if the averaged stress level is relatively low. It is especially likely to be in the case of large - scaled dynamic loadings where besides the constant gravity acting on the massif there occur additional body forces - mertial forces - which are able to initiate the loss of rock block stability. The deformations which are originated in this case and are localised in the soft interblock gaps, i.e. faults, joints, and fractured zones can attain very considerable values. Several mechanisms of excavation destruction should be noted (here we confine our consideration by a sufficiently long - period wave so that we could avoid the spalling effect). EXPERIMENTAL RESULTS. The underground nuclear explosions are considered to be an ideal tool for the investigations of rock deformation properties. A large scale of loadings, a wide range of amplitude and a lot of instrumental and visual observations which were carried out during many years of tests, make it possible to analyse the rock massif structure effect on the process of rock deformation and the destruction of rock.
- Geology > Geological Subdiscipline > Geomechanics (0.66)
- Geology > Structural Geology (0.46)