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1.
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2.
Summary The laboratory testing program reported herein describes the statistical correlations of unconfined compressive strength ( c ), Young's modulus (E t50), and modulus ratio (MR) to their coefficients of variation (CV( c ), CV(E t50), and CV(MR)). Negative correlation of both c andE t50 to CV( c ) indicates that data scatter tends to decrease with increasing strength and stiffness. A positive correlation between MR and CV( c ) indicates that stiffer rocks are more variable for a given compressive strength.  相似文献   

3.
Summary Thirteen natural rock profiles (Barton and Choubey, 1977) are analyzed for their fractal properties. Most of the profiles were found to approximate fractal curves but some also showed features of specific wavelengths and amplitudes superimposed on fractal characteristics. The profiles showed fractal dimensions from 1.1 to 1.5 covering a range of selfsimilar and self-affine curves. The analysis results suggest a negative correlation between fractal dimension,D, and amplitude,A. Joint roughness coefficients (JRC) show a positive correlation with amplitude,A, and a negative correlation with fractal dimension,D. A numerical model of fracture closure is used to investigate the effects of different profile characteristics (D, A and sample size) on the nature of dilation and contact area, using the natural profiles and synthetic fractional Brownian motion profiles. Smooth profiles (low JRC, highD, lowA) display many small contact regions whereas rough fractures (high JRC, lowD, highA) display few large contact areas. The agreement with published experimental data supports the suggested correlations between JRC and the fractal parameters,A andD. It is suggested that observed scale effects in JRC and joint dilation can be explained by small differential strain discontinuities across fractures, which originate at the time of fracture formation.  相似文献   

4.
Summary The hoop forces which develop in circular tubes buried in elastic-plastic ground are investigated. A closed form solution is used to determine the hoop forces which develop when the field stresses in the elastic-plastic ground are initially uniform. The finite element method is used to solve the problem for biaxial field stress. A parametric study is undertaken to assess the influence of tube stiffness and ground strength on the hoop forces, and use is made of elastic stress contours to predict the likely extent of material failure around tubes buried in ground with biaxial prestress.Notation a tube radius - c cohesion - D flexural stiffness of the structure - E i Young's modulus of structure - E s Young's modulus of ground - F hoop force (compression positive) - G s shear modulus of ground - H hoop stiffness of the structure - K coefficient of lateral pressure - N tan2(45+/2) - q ( 1– 1)/2 - S f relative flexural stiffness of the structure - S h relative hoop stiffness of the structure - t structural thickness - v circumferential displacement - w radial displacement - v l Poisson's ratio of structure - v s Poisson's ratio of ground - normal traction acting on the structure - d deviatoric component of field stress - h horizontal field stress - m uniform component of field stress - v vertical field stress - 1 major principal stress - 3 minor principal stress - tangential traction acting on the structure - angle of internal friction of the ground - angle of dilation of the ground  相似文献   

5.
Zusammenfassung Offene Faltung in proterozoischen Tilliten der Huronian Supergroup führte zu geringen Differentialverschiebungen zwischen Matrix und Grobkomponenten innerhalb von konglomeratischen Schichtgliedern. Einmessung der aus der Bewegung resultierenden Striemungen und feiner Risse erlaubt die Bestimmung der regionalen Spannungsachsen (1 > 2 > 3).
Deformation mechanics of an open conglomerate fabric—A contribution to static tectonics
Summary Open folding of Proterozoic tillites (Huronian Supergroup) caused minor differential displacements between matrix and clasts within conglomeratic units. Detailed measurements of striations and ruptures along the clast surface permitted the deduction of regional stress axes (1 > 2 > 3).

Mit 6 Abbildungen

Herrn Prof. Dr. Dr. h. c.B. Sander zum 90. Geburtstag gewidmet.  相似文献   

6.
Cubic specimens of fine-grained artifical polycristalline rock salt were deformed at different principal stresses in the range of 20–200° C. The data from different types of tests are compared by plotting 1–3 against 1, 2, 3. The deformation behavior is highly influenced by the intermediate principal stress 2. An increase of the intermediate stress from compression (1>2=3) to extension (1=2>3) lowers the rate of deformation. An increase of temperature always gives rise to an increase of deformation rate.Translation gliding on (110) is assumed to be the dominant flow mechanism. Textural changes and development of preferred orientation were investigated by means of the X-ray diffractometer. Intensities were measured for (110), (111), and (100). Compression leads to girdle occupations about the unique principle compressive axis, extension to girdles about the unique principle axis of extension. When all principle stresses are different the polfigures tend to a position intermediate between the two occupations.  相似文献   

7.
Summary Results of resonant column tests were used to determine values of low amplitude shear modulus (G 0) of a remoulded kaolinite clay for different durations of ageing and for different values of consolidation stress (0) and overconsolidation ratio (OCR). It was found that after completion of primary consolidation the values of G 0 increased linearly with the logarithm of time and after a week of confinement the value of normalized rate of secondary increase of shear modulus (N G ) could be reliably estimated. Values of N G were found to derease linearly with the logarithm of OCR and with the logarithm of ageing duration. This similarity of behaviour provided a basis for establishing an equivalency between age and equivalent overconsolidation ratio (OCR)eq. The effects of 0 and OCR on the value of G 0 were also established in a functional form that indicated a stronger influence compared to that predicted by the Hardin Equation.  相似文献   

8.
The Pillara Zn–Pb deposit is the largest of several known Mississippi Valley-type (MVT) deposits in the Lennard Shelf of the Canning Basin. Paleomagnetic and rock magnetic measurements are reported for 294 specimens from 23 sites in mineralization and its carbonate host rocks from the deposit as well as on 15 artificial specimens of zinc and lead concentrate and of tailings. Pyrrhotite carries the characteristic remanent magnetization (ChRM) in nearly all specimens. The ChRM postdates most faulting as shown by breccia tests and most minor regional tilting as shown by the degraded fit on tilt correction. The mean ChRM direction for all sites is D=20.6°, I=–27.5° (N=23, 95=5.3°, k=34.1), yielding an age of 358±5 Ma (2) that is similar to the comparable age of 354±8 Ma (2) for the Kapok MVT deposit. Host rock diagenesis with attendant secondary remagnetization yields an age of 361±5 Ma (1) and the MVT mineralization with a primary chemical remanent magnetization gives an age of 356±3 Ma (1), co-eval with a published Rb–Sr sphalerite age of 357±3 Ma. Interpretation of this temporal data suggests that the MVT deposits of the southeastern Lennard Shelf originated during extension, probably in response to rift-related topography-driven fluid flow.Editorial handling: C. Brauhart  相似文献   

9.
Two-dimensional Hurst Index of Joint Surfaces   总被引：2，自引：1，他引：2  
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10.
An internal variable model for the creep of rocksalt   总被引：3，自引：0，他引：3  
Summary The creep strain rate of rocksalt, like that of other ductile crystalline materials, can be described by a power law equation of the type ( ) n , where the active stress is the difference between the total deviatoric applied stress and an internal stress i . In this paper, the origin and the nature of this internal stress, which develops during inelastic deformation of the material, are discussed. It is shown that this internal stress can serve as an internal (or state) variable in the constitutive model of rocksalt, which reflects the microstructure evolution of the material under the competitive action of hardening and recovery mechanisms.An analysis of experimental data, both our own and those taken from the literature, demonstrates that such a law is able to correctly reproduce rocksalt creep test results in the steady-state domain. The proposed model is in accordance with the macroscopic and microscopic behavior of salt, and with direct measurements of the internal stresses made by others on this material.  相似文献   

11.
Axial-symmetric and real triaxial deformation tests on Solnhofen limestones were made in the range of 20 to 650° C. Stress, strain and time observations as functions of temperature and the ratios of the external stresses are plotted as stress-strain and strain-time curves. Mechanical twinning on e (01¯12) and syntectonic recrystallization (at temperatures above 500° C) is assumed to be the dominant flow mechanism. On samples of high permanent strain the textural changes and development of preferred orientations were investigated by means of the X-ray diffractometer. In all tests the symmetry of the polefigures is exactly identical with the symmetry of the external stress-field.In tests with 1>2=3 the poles of the planes investigated (10¯11; 10¯12; 11¯20) occupy girdles about the unique principle compressive axis. When all principle stresses are different (1>2>3) the poles of the planes investigated tend to maxima (in the case of plane strain) ore to girdle-occupations about the principle axis of maximum extension. The deduced c-diagrams show a fairly similar tendency of the spacial orientations.The pole figures (as well as the calculated orientation of the c-axis) must be explained by the superposition of reflected intensities on planes in twinned and untwinned grains. In every diagram partial occupations—possibly representing the orientations of twinned grains-are in fairly good agreement with the orientation predicted by the theory of Brace-MacDonald for the stable orientation of anisotropic minerals in a non-hydrostatic stress-field.

Herrn Prof. Dr. F. Karl danke ich sehr herzlich für zahlreiche Diskussionen sowie für die kritische Durchsicht des Manuskripts. Mein Dank gilt auch der Deutschen Forschungsgemeinschaft, welche die Untersuchung durch eine Sachbeihilfe unterstützte.  相似文献   

12.
High-grade iron mineralisation (>65%Fe) in the North Deposit occurs as an E-W trending synclinal sheet within banded iron formation (BIF) of the Early Proterozoic Dales Gorge Member and consists of martite-microplaty hematite ore. Three hypogene alteration zones between unmineralised BIF and high-grade iron ore are observed: (1) distal magnetite-siderite-iron silicate, (2) intermediate hematite-ankerite-magnetite, and (3) proximal martite-microplaty hematite-apatite alteration zones. Fluid inclusions trapped in ankerite within ankerite-hematite veins in the hematite-ankerite-magnetite alteration zone revealed mostly H2O–CaCl2 pseudosecondary and secondary inclusions with salinities of 23.9±1.5 (1, n=38) and 24.4±1.5 (1, n=66) eq.wt.% CaCl2, respectively. Pseudosecondary inclusions homogenised at 253±59.9°C (1, n=34) and secondary inclusions at 117±10.0°C (1, n=66). The decrepitation of pseudosecondary inclusions above 350°C suggests that their trapping temperatures are likely to be higher (i.e. 400°C). Hypogene siderite and ankerite from magnetite-siderite-iron silicate and hematite-ankerite-magnetite alteration zones have similar oxygen isotope compositions, but increasingly enriched carbon isotopes from magnetite-siderite-iron silicate alteration (–8.8±0.7, 1, n=17) to hematite-ankerite-magnetite alteration zones (–4.9±2.2, 1, n=17) when compared to the dolomite in the Wittenoom Formation (0.9±0.7, 1, n=15) that underlies the deposit. A two-stage hydrothermal-supergene model is proposed for the formation of the North Deposit. Early 1a hypogene alteration involved the upward movement of hydrothermal, CaCl2-rich brines (150–250°C), likely from the carbonate-rich Wittenoom Formation (13C signature of 0.9±0.7, 1, n=15), within large-scale folds of the Dales Gorge Member. Fluid rock reactions transformed unmineralised BIF to magnetite siderite-iron silicate BIF, with subsequent desilicification of the chert bands. Stage 1b hypogene alteration is characterised by an increase in temperature (possibly to 400°C), depleted 13C signature of –4.9±2.2 (1, n=17), and the formation of hematite-ankerite-magnetite alteration and finally the crystallisation of microplaty hematite. Late Stage 1c hypogene alteration involved the interaction of low temperature (~120°C) basinal brines with the hematite-ankerite-magnetite hydrothermal assemblage leaving a porous martite-microplaty hematite-apatite mineral assemblage. Stage 2 supergene enrichment in the Tertiary resulted in the removal of residual ankerite and apatite and the weathering of the shale bands to clay.Editorial handling: B. Lehmann  相似文献   

13.
The shear strength of rock joints in theory and practice   总被引：62，自引：10，他引：62  
SummaryThe Shear Strength of Rock Joints in Theory and Practice The paper describes an empirical law of friction for rock joints which can be used both for extrapolating and predicting shear strength data. The equation is based on three index parameters; the joint roughness coefficientJRC, the joint wall compressive strengthJCS, and the residual friction angle r . All these index values can be measured in the laboratory. They can also be measured in the field. Index tests and subsequent shear box tests on more than 100 joint samples have demonstrated that r can be estimated to within ± 1° for any one of the eight rock types investigated. The mean value of the peak shear strength angle (arctan/ n ) for the same 100 joints was estimated to within 1/2°. The exceptionally close prediction of peak strength is made possible by performing self-weight (low stress) sliding tests on blocks with throughgoing joints. The total friction angle (arctan/ n ) at which sliding occurs provides an estimate of the joint roughness coefficientJRC. The latter is constant over a range of effective normal stress of at least four orders of magnitude. However, it is found that bothJRC andJCS reduce with increasing joint length. Increasing the length of joint therefore reduces not only the peak shear strength, but also the peak dilation angle and the peak shear stiffness. These important scale effects can be predicted at a fraction of the cost of performing large scale in situ direct shear tests.With 20 Figures  相似文献   

14.
Summary The new mineral orschallite, Ca3(SO3)2SO4 · 12H2O, was found at the Hannebacher Ley near Hannebach, Eifel, Germany. Crystal structure analysis of the mineral, chemical analysis and water determination on synthetic material gave the composition Ca3(SO3)2SO4 · 12H2O. The mineral crystallizes in space group with a = 11.350(1), c = 28.321(2) Å, V = 3159.7 Å3, Z = 6, Dc = 1.87 Mg/m3, Dm = 1.90(3) Mg/m3. It is uniaxial positive with the optical constants = 1.4941, = 1.4960(4). The strongest lines in the powder pattern are (d-value (Å), I, hkl) 5.73, 100, 1 0 4/8.11, 80, 0 1 2/2.69, 80, 3 0 6/3.63, 60, 1 1 6/3.28, 40, 3 0 0. Refinement of the crystal structure led to a weighted residual of Rw = 0.043 for 600 observed reflections with I > 2(I) and 52 variable parameters.
Orschallit, Ca3(SO3)2SO4 · 12H2O, ein neues Kalzium-Sulfat-Sulfat-Hydrat-Mineral
Zusammenfassung Das neue Mineral Orschallit, Ca3(SO3)2SO4 · 12H2O, wurde in der Hannebacher Ley bei Hannebach, Eifel, Deutschland gefunden. Eine Analyse der Kristallstruktur an einem Einkristall des natürlichen Materials, chemische Analyse und Wasserbestimmung an synthetischem Material ergaben die Zusammensetzung Ca3(SO3)2SO4 · 12H2O. Das Mineral kristallisiert in der Raumgruppe mit a = 11.350(1), c = 28.321(2) Å, V = 3159.7 Å3, Z = 6, Dc = 1.87 Mg/m3, Dm = 1.90(3) Mg/m3. Es ist optisch einachsig mit den optischen Konstanten = 1.4941, = 1.4960(4). Die stärksten Linien des Pulver-diagramms liegen bei (d-Wert (Å), I, hkl) 5.73, 100, 1 0 4/8.11, 80, 0 1 2/2.69, 80, 3 0 6/3.63, 60; 1 1 6/3.28, 40, 3 0 0. Die Verfeinerung der Kristallstruktur ergab einen gewichteten Residualwert Rw = 0.043 für 600 beobachtete Reflexe mit I > 2(I) und 52 variable Parameter.

With 5 Figures  相似文献   

15.
Sm-Nd systematics for nine whole-rock samples of hornblende norites, pyroxenites and a lamprophyre from various parts of the Cortlandt Complex were analyzed. Six of these samples from the central and eastern parts of the complex give an isochron age of 430±34 (2) Ma with an Nd value of –2.9±0.5, and the other three samples from the western part, including the lamprophyre, define a similar age of 394±33 (2) Ma but with a distinctly different Nd value of –1.4±0.4. The two different initial 143Nd/144Nd ratios corresponding to these -values are interpreted to reflect continental crustal contamination of the lamprophyric parental liquid prior to final emplacement and crystal fractionation to produce the different rock types of the complex. The intrusion age of 430 Ma for the complex clearly post-dates the major metamorphic event of the Taconic orogeny. The Nd-isotopic data also suggest a relationship between the Cortlandt Complex and a belt of lamprophyric dike rocks to the west, known as the Beemerville trend, which cuts across the metamorphic trends of the Taconic (Ratcliffe 1981).  相似文献   

16.
The concept of an ideal rock texture, in which crystals are distributed randomly in space, is proposed for use in general analysis of rock textures. The spatial correlation function for the ideal rock texture was examined and the function, a specific kind of spatial correlation function, is related to crystal size distribution and to some extent to crystal boundaries. The function is unity at distance zero, and monotonically decreases with increasing distance for the ideal texture. This behavior of the function is observed for any size distribution. In an ideal texture, the function is directly related to crystal size distribution and crystal shape. It is important in stereology because the crystal size distribution in three dimensions may be deduced from analyzing a function that is obtained from analyzing two-dimensional section images. Crystal shape is also related to the function. If crystals are concave in shape, or have inclusions of other phases, the function may show a hump or plateau when plotted against distance. However, the crystal shape effect cannot produce values smaller than zero. If values become negative, the texture is no longer considered ideal. The ideal textures for two model size distributions—step and delta functions—are considered. The rate of decrease of values is more strongly dependent on size distribution than on system dimension.  相似文献   

17.
DC and AC electrical conductivities were measured on samples of two different crystals of the mineral aegirine (NaFeSi2O6) parallel () and perpendicular () to the [001] direction of the clinopyroxene structure between 200 and 600 K. Impedance spectroscopy was applied (20 Hz–1 MHz) and the bulk DC conductivity DC was determined by extrapolating AC data to zero frequency. In both directions, the log DC – 1/T curves bend slightly. In the high- and low-temperature limits, differential activation energies were derived for measurements [001] of EA 0.45 and 0.35 eV, respectively, and the numbers [001] are very similar. The value of DC [001] with DC(300 K) 2.0 × 10–6 –1cm–1 is by a factor of 2–10 above that measured [001], depending on temperature, which means anisotropic charge transport. Below 350 K, the AC conductivity () (/2=frequency) is enhanced relative to DC for both directions with an increasing difference for rising frequencies on lowering the temperature. An approximate power law for () is noted at higher frequencies and low temperatures with () s, which is frequently observed on amorphous and disordered semiconductors. Scaling of () data is possible with reference to DC, which results in a quasi-universal curve for different temperatures. An attempt was made to discuss DC and AC results in the light of theoretical models of hopping charge transport and of a possible Fe2+ Fe3+ electron hopping mechanism. The thermopower (Seebeck effect) in the temperature range 360 K < T <770 K is negative in both directions. There is a linear – 1/T relationship above 400 K with activation energy E 0.030 eV [001] and 0.070 eV [001]. 57Fe Mössbauer spectroscopy was applied to detect Fe2+ in addition to the dominating concentration of Fe3+.  相似文献   

18.
The friction and deformation behaviour of rock joints   总被引：2，自引：3，他引：2  
SummaryThe Friction and Deformation Behaviour of Rock Joints The present investigation deals with the influence of joint roughness and material strength on the friction and deformation behaviour of rough indented joints. Besides the analytical determination of the joint roughness by the dilatation behaviour of the joint, friction tests on models with natural joint morphology and rock samples have been conducted.A material law is developed, describing the friction resistance and the dilatation behaviour at large deformations in their dependence on normal stress and material strength.
ZusammenfassungDas Reibungs- und Verformungsverhalten von Klüften Die vorliegende Untersuchung war dem Einfluß der Kluftflächenunebenheit und der Materialfestigkeit auf das Reibungs- und Verformungsverhalten rauher, verzahnter Kluftflächen gewidmet.Neben der analytischen Bestimmung der Kluftflächenunebenheit anhand des Dilatationsverhaltens der Kluftfuge wurden Reibungsversuche an Modellkörpern mit natürlicher Kluftmorphologie und an Gesteinen durchgeführt. Es wird ein Stoffgesetz entwickelt, mit welchem der Reibungswiderstand und das Dilatationsverhalten in Abhängigkeit von der Normalspannung und der Materialfestigkeit bei längeren Gleitwegen beschrieben werden kann.
RésuméLe comportement des fissures au frottement et aux déformations La présente étude traite de l'influence de la rugosité d'une diaclase et de la résistance de la roche sur le comportement au frottement et aux déformations d'une fissure âpre et endentée. La rugosité de la fissure a été déterminée d'après la dilatation maximale. Des éssais de frottement ont été exécutés à l'aide de modèles ayant une surface de fissure naturelle et à l'aide d'échantillons de roche. Une loi a été développée qui décrit la resistancé au frottement et le comportement à la dilatation de la fissure pour de grandes déformations en fonction de la contrainte normale et de la résistance des matériaux.
List of Symbols h dilatation - i deviation angle, dilatation angle - s shear deformation - residual friction angle - normal stress - F tensile strength - shear stress With 15 Figures  相似文献   

19.
Modeling soil variability as a random field   总被引：1，自引：0，他引：1  
The observed variability in the spatial distribution of soil properties suggests that it is natural to describe such distribution as a random field. One of the ways to study engineering problems in such a stochastic setting is by the use of the Monte-Carlo simulation procedure. Application of this technique requires the capability to generate a large number of realizations of a given random field. A numerical procedure for the generation of such realizations in two-dimensional space is introduced as a finite difference approximation of a stochastic differential equation. The equation used was that suggested by Heine (1955). The resulting procedure is essentially similar to other autoregressive procedures used for the same purpose (Whittle, 1954; Smith and Freeze, 1979). However, contrary to these procedures, the present one is defined in terms of physically significant parameters:r 0, the autocorrelation distance;, the discretization size; and the standard deviation, . Formulating the simulation procedure in terms of the physically significant parameters (r 0,, ) greatly simplifies the task of generating realizations that are compatable with a given soil deposit.  相似文献   

20.
The Tojottamanselkä gneisses of the Koitelainen region, northern Finland, have been dated by the Sm-Nd and the common Pb methods. The Sm-Nd data of seven samples from a small area (100 m × 100 m) define an isochron ofT=3.06±0.12 (2) Ga, with correspondingI Nd=0.50848±9 (2), or Nd(T)=–3.7±1.8. This age is in good agreement with the zircon U-Pb discordia age (3.1 Ga) reported by Kröner et al. (1981) and is interpreted as the time of magmatic emplacement. The distinctly negative Nd(T) value is found for the first time for Archean tonalitic gneisses and implies derivation of these magmas by remelting of continental material with a long (200–500 Ma) crustal residence time. A few samples, on the other hand, possess Nd(T) values close to zero, hence they are thought to be derived by partial melting of basaltic sources with nearchondritic REE distribution patterns.Common Pb isotopic data yield an isochron age of 2.64±0.24 (2) Ga which is in agreement, within error limit, with the published Rb-Sr isochron age of 2.73±0.24 Ga (Kröner et al. 1981). The age of ca. 2.7 Ga is interpreted as the time of regional metamorphism during which both Pb and Sr isotopes were rehomogenised.The tonalitic gneisses have highly fractionated REE patterns with (La/Yb)N ratios varying from 9 to 43. Like most Archean gneisses of TTG composition (tonalite-trondhjemite-granodiorite), they could be derived by partial melting of crustal sources of basaltic to granodioritic compositions. Direct derivation by melting of mantle peridotites is excluded.The present geochemical study indicates that the Tojottamanselkä gneisses have had a very complex history that involved multi-stage development. Together with the published age data for the basement gneisses and greenstone belts of eastern central Finland (Vidal et al. 1980; Martin et al. 1983a), we conclude that the Archean crustal development in Finland started at least 3.5 Ga ago and passed through a series of magmatic and metamorphic events at 3.1, 2.85, 2.65 and 2.5 Ga before the final intrusions of K-rich granites about 2.4 Ga ago.  相似文献   

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