No description available.

Detailed structural and petrographic studies of the Hylas zone northwest of Richmond, Virginia, reveal that Late Paleozoic thrusting to the northwest produced a zone of protomylonite, mylonite and ultramylonite from felsic gneiss and amphibolite. The thrusting event, which initiated retrograde metamorphism to greenschist facies, carried an allochthonous plate of coarse-grained, locally porphyry tic Petersburg(?) Granite over a layered sequence of metamorphosed sedimentary and volcanic rocks now represented by biotite gneiss, biotite schist and amphibolite. Non-cataclastic rocks west of the Hylas zone have undergone at least two periods of deformation (DI,D2) prior to cataclasis. Prograde metamorphism (MI) was concurrent with deformation and is inferred to have occurred about 342 ± 70 m.y. ago. The Hylas zone deformation (D3) caused a pervasive cataclastic foliation (Sc) and a later widely spaced shear cleavage (Ss ) to be formed in rocks in the fault zone. Deformation was accompanied by retrograde metamorphism (m2) to greenschist facies mineral assemblages. Fracturing and high angle faulting (D4) was superimposed on the Hylas zone about 221 ± 6 m.y. ago under zeolite facies temperatures and pressures;laumontite, calcite and quartz crystallized in open spaces at this time. Sedimentation in the basin created by D4 faulting and downwarp occurred during Late Triassic time to form the Richmond Basin. Northwest-trending joints and faults appear to have formed post-221 m.y. ago and pre-Cretaceous time. Cenozoic reverse faulting along strike of the Hylas zone in the Coastal Plain of Maryland may indicate a continuation of this polytectonic zone to the north. / Master of Science

Thesis (MSc)--Stellenbosch University, 2013. / ENGLISH ABSTRACT: Rhythmic magmatic layering in granites is an intriguing feature that has been reported from plutons with contrasting chemical compositions from a wide range of tectonic settings. Layered granites are rare and occur in association with volumetrically dominant non-layered rocks having similar composition. Understanding the origin of such layering in granites, particularly from well exposed outcrops, may give crucial insights on the physical-chemical conditions and processes (such as fractional crystallization, size and composition of individual magma batches, efficiency of mixing between batches etc.) within magma chambers during their construction. In the Cape Granite Suite, rhythmic layering is exceptionally well preserved in outcrops of the S-type granodioritic to monzogranitic Peninsula pluton along the coastline of the small town of Llandudno. At Llandudno, the granodioritic facies of the Peninsula pluton is exposed as a coarse-grained, cordierite and K-feldspar phenocrystic granite (referred to as Llandudno granodiorite in this study). Layering within the Llandudno granodiorite occurs within several lens-shaped bodies, of which the largest, with a thickness of about 5 m. The studied rhythmic sequence comprises 50 layers with thicknesses ranging between 5 and 50 cm. Each layer is typically characterised by a sharp lower contact overlain by a biotite-rich portion containing approximately 50 vol. % biotite. This mafic lower portion, grades upwards into a strongly leucocratic upper portion enriched in quartz, plagioclase and K-feldspar. The layered rocks host a substantially lower abundance of K-feldspar megacrysts and cordierite than the surrounding Llandudno granodiorite. In particular, cordierite crystals are five times less abundant in the layered zone than the un-layered Llandudno granodiorite. The K-Feldspars megacrysts that do occur within the layering are generally concentrated in the mafic part of some of the layers and are commonly oriented parallel to the layering. The K-feldspar megacrysts are significantly smaller than those in Llandudno granodiorite, but were found to be similar in composition. The whole rock compositions of the layered rocks are peraluminous with A/CNK >1.4. They have lower Mg#s (51 to 58) than the Llandudno granodiorite (51 to 65). The Na2O/CaO ratio of mafic and leucocratic portions is higher than in the Peninsula pluton. The mafic portions show an enrichment of trace and rare earth elements relative to the leucocratic portions and Peninsula pluton. The difference in bulk rock composition as well as trace and rare earth elements composition shows that the layered rocks were not formed by magmas produced by differentiation of the Llandudno granodiorite. The differences in biotite composition in basal sections of adjacent layers suggest that each layer represents a separate magma pulse, with the mafic portions of the layers largely representing an accumulation of the crystals in the magma batch at the time of injection and that these crystals mostly consist of orthopyroxene and biotite. This is in agreement with the findings based on the whole rock chemistry of the layers compared with the Llandudno granodiorite. The inclusion of K-feldspar megacrysts from the host granite into the layering, as well as the exceptional state of preservation of the layering, suggests that the layering formed relatively late in the crystallization sequence of the granite. This, in combination with the evidence for subtle differences in the chemistry of the magmas that formed separate layers, suggests that the layers represent a frozen feeder zone in the Peninsula pluton recording small successive pulses of magma addition. Frequent occurrence of the less-preserved layered biotite schlieren in the pluton may represent the equivalents of the layering that have become partially digested and texturally equilibrated with the host magma. / AFRIKAANSE OPSOMMING: Ritmiese magmatiese gelaagdheid in graniet is ’n interessante kenmerk van plutone met teenstellende chemiese samestellings in ’n wye verskeidenheid tektoniese omgewings. Gelaagde graniet is seldsaam en kom saam met volumetries dominante, niegelaagde gesteentes met soortgelyke samestellings voor. ’n Begrip van die oorsprong van hierdie gelaagdheid in graniet, veral in goed sigbare dagsome, kan belangrike insig verleen in die fisies-chemiese omstandighede en prosesse (soos fraksionele kristallisasie, die grootte en samestelling van individuele volumes magma, die doeltreffendheid van volume-vermenging, ensovoorts) in magmakamers gedurende die vorming daarvan. In die Kaapse granietgroep het ritmiese gelaagdheid besonder goed behoue gebly in dagsome van die S-tipe granodioritiese tot monsogranitiese Skiereilandse plutoon langs die kuslyn van die voorstad Llandudno. Die granodioritiese fasies van die Skiereilandse plutoon by Llandudno manifesteer in die vorm van ’n grofkorrelrige, kordiëritiese en K-veldspatiese fenokris-graniet (wat in hierdie studie Llandudno-granodioriet genoem word). Gelaagdheid in die Llandudno-granodioriet kom voor in verskeie lensvormige massas, waarvan die grootste sowat 5 m dik is. Die bestudeerde ritmiese opeenvolging bestaan uit 50 lae met diktes van tussen 5 cm en 50 cm. Elke laag word gekenmerk deur ’n skerp onderste kontakvlak wat bedek is met ’n biotiet-ryke gedeelte wat uit sowat 50 vol % biotiet bestaan. Hierdie mafiese onderste gedeelte gradeer opwaarts in ’n sterk leukokratiese boonste gedeelte wat ryk is aan kwarts, plagioklaas en K-veldspaat. Die gelaagde gesteentes bevat beduidend minder K-veldspatiese megakriste en kordiëriet as die omliggende Llandudno-granodioriet. Die kordiëritiese kristalle in besonder kom vyf keer minder in die gelaagde sone as in die niegelaagde Llandudno-granodioriet voor. Die K-veldspatiese megakriste wat wél in die gelaagdheid voorkom, is oor die algemeen in die mafiese gedeelte van sommige lae gekonsentreer, en is meestal parallel met die gelaagdheid georiënteerd. Die K-veldspatiese megakriste is aansienlik kleiner as dié in die Llandudno-granodioriet, maar het ’n soortgelyke samestelling. Die heelrots-samestellings van die gelaagde gesteentes is peralumineus, met A/CNK >1,4. Dit toon ook laer Mg#s (51 tot 58) as die Llandudno-granodioriet (51 tot 65). Die Na2O/CaO-verhouding van die mafiese en leukokratiese gedeeltes is hoër as in die Skiereilandse plutoon. In die mafiese gedeeltes is daar ‘n verryking in spoor- en skaarsaarde-elemente relatief tot die leukokratiese gedeeltes sowel as die Skiereilandse plutoon. Die verskil in heelrots-samestelling sowel as spoor- en seldsame-aardelementsamestelling toon dat die gelaagde gesteentes nié gevorm is deur magmas wat uit differensiasie van die Llandudno-granodioriet ontstaan het nie. Uit die verskille in die biotiet-samestelling van basissnitte uit aanliggende lae word afgelei dat elke laag ’n afsonderlike magmapuls verteenwoordig, terwyl die mafiese gedeeltes van die lae hoofsaaklik ‘n versameling van kristalle verteenwoordig wat tydens inplasing van die magma volume gevorm het, meestal ortopirokseen en biotiet. Dít stem ooreen met die bevindinge rakende die heelrots-chemie van die lae in vergelyking met die Llandudno-granodioriet. Die insluiting van K-veldspatiese megakriste vanaf die moedergraniet by die gelaagdheid, dui daarop dat die gelaagdheid betreklik laat in die kristallisasie-orde van die graniet gevorm het. Dít, tesame met bewyse van subtiele verskille in die chemie van die magmas waaruit afsonderlike lae gevorm is, dui daarop dat die lae ’n bevrore toevoersone in die Skiereilandse plutoon uitmaak wat kort, opeenvolgende pulse van magmatoevoeging vasgevang het. Die gereelde voorkoms van swakker bewaarde, gelaagde biotiet-sliere in die plutoon kan moontlik dui op sones van die gelaagdheid wat gedeeltelik verteer is en tekstureel met die moedermagma ge-ekwilbreer het.

Le domaine allochtone de la chaîne Neoproterozoïque Araçuaí met en jeu de grandes quantités de magma, de la fusion partielle et un gradient thermique élevé, ce que caractérise cette chaîne comme un orogène chaud. La suite tonalitique Galiléia, mise en place dans des métasédiments et déformée à l'état magmatique, représente un énorme batholite qui a fortement influencé le comportement mécanique de la croûte moyenne. L'anisotropie de susceptibilité magnétique (ASM) mesurée à travers le batholite et utilisé comme proxy de la petrofabrique, associé à une étude de la minéralogie magnétique, a permit de définir le comportement paramagnétique de la suite Galiléia et de mettre en évidence une déformation complexe en 3D. Les structures développées dans le magma visqueux résultent d'une combinaison de tectoniques tangentielles induites par la compression, et de forces gravitaires découlant du poids de la croûte sus-jacente. La dynamique du batholite est compatible avec celles déjà décrites pour des roches ductiles d'orogènes chauds. Les datations U/Pb sur zircon et monazites et 40Ar/39Ar sur amphiboles, muscovites et biotites ont permit la caractérisation de l'évolution t hermique du batholite et de contraindre la durée de la déformation. Le batholite Galiléia s'est mis en place à ~580 Ma, au cours d'un important événement magmatique, tectonique et thermique. Les températures sont restées hautes durant les premiers ~50 Ma de l'évolution thermique, favorisant une déformation constante du batholite à l'état magmatique, pendant plusieurs dizaine de millions d'années. De telles hautes températures et une telle déformation stable durant de si longues périodes sont des caractéristiques qui semblent communes au orogènes chaud. Le refroidissement lent estimé à 10°C/Ma après ~500 Ma indique l'exhumation a été très lente, probablement due à l'érosion uniquement. / The allochtonous domain of the Neoproterozoic Araçuaí belt involves large amounts of magma, widespread partial melting, granulitic facies and high geotherm, characterising this belt as a hot orogen. The Galiléia tonalitic suite, emplaced within host metasediments and deformed at magmatic state, represents a huge batholith that strongly influenced the mechanical behaviour of this middle crust. The anisotropy of magnetic susceptibility (AMS) measured through this batholith and used as a petrofabric proxy, combined to a detailed magnetic mineralogy investigation, permitted to characterize the paramagnetic behaviour of the Galiléia suite and therefore to highlight a complex 3D strain deformation. The observed structures developed within the viscous magma resulted from a combination of tangential tectonics induced by the compression, and gravitational forces arising from the load of the overlying crust. The kinematics of the batholith is compatible with that already described for ductile rocks of hot orogens. U/Pb dating on zircons and monazites together with 40Ar/39Ar dating on amphiboles, muscovites and biotites permitted to define the thermal evolution of the Galiléia batholith and its host metasediments and constrain the timing of the deformation. The Galiléia batholith emplaced during an important magmatic, tectonic and thermal event at ~580 Ma. Temperature remained high during the first ~50 Ma of the thermal evolution, promoting a seemingly constant deformation of the batholith at magmatic state during several tens of millions years. Such high temperature conditions and stable deformation kinematics during protracted periods of time are supposed to be characteristic of hot orogen. The slow cooling rate of ~10°C/Ma evidenced after ~500 Ma probably indicate a very slow exhumation probably only conducted by erosion.

Choi, Yuk Kam. / Thesis submitted in: December 2008. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2009. / Includes bibliographical references (leaves 204-221). / Abstracts in English and Chinese. / Abstract --- p.i / Abstact (in Chinese) --- p.iv / Acknowlegement --- p.vi / Table of contents --- p.viii / List of tables --- p.xiii / List of figures --- p.xv / List of plates --- p.xvi / Chapter CHAPTER 1 --- INTRODUCTION --- p.1 / Chapter 1.1 --- Research background --- p.1 / Chapter 1.2 --- Conceptual framework --- p.3 / Chapter 1.3 --- Research objectives --- p.10 / Chapter 1.4 --- Significance of the study --- p.10 / Chapter 1.5 --- Organization of this thesis --- p.11 / Chapter CHAPTER 2 --- LITERATURE REVIEW --- p.13 / Chapter 2.1 --- Introduction --- p.13 / Chapter 2.2 --- Hong Kong's forestry and use of native species in ecological restoration --- p.14 / Chapter 2.3 --- Factors limiting the use of native species in ecological rehabilitation --- p.17 / Chapter 2.4 --- The climate and soils in Hong Kong --- p.19 / Chapter 2.5 --- Soil physical properties --- p.22 / Chapter 2.5.1 --- Soil water and water holding capacity --- p.23 / Chapter 2.5.2 --- Penetration resistance --- p.26 / Chapter 2.5.3 --- Soil structure --- p.27 / Chapter 2.6 --- Soil amendment materials --- p.29 / Chapter 2.6.1 --- Compost --- p.30 / Chapter 2.6.2 --- Coconut meal --- p.32 / Chapter 2.6.3 --- Water absorbing polymer --- p.35 / Chapter 2.7 --- Summary --- p.39 / Chapter CHAPTER 3 --- EFFECT OF AMENDMENT MATERIALS ON PHYSICAL PROPERTIES OF DECOMPOSED GRANITE AND THE GROWTH OF SCHIMA SUPERBA : GREENHOUSE EXPERIMENT I --- p.41 / Chapter 3.1 --- Introduction --- p.41 / Chapter 3.2 --- Materials and methods --- p.42 / Chapter 3.3 --- Experimental design --- p.43 / Chapter 3.3.1 --- "Amending DG with water absorbing polymer, coconut meal and compost" --- p.43 / Chapter 3.3.2 --- Watering treatment --- p.45 / Chapter 3.3.3 --- Post-planting treatment --- p.47 / Chapter 3.3.4 --- Monitoring of penetration resistance and soil moisture content --- p.48 / Chapter 3.4 --- Plant growth measurement --- p.49 / Chapter 3.4.1 --- Survival rate --- p.49 / Chapter 3.4.2 --- Height and basal diameter --- p.49 / Chapter 3.4.3 --- Chlorophyll fluorescence --- p.49 / Chapter 3.4.4 --- Aboveground biomass --- p.50 / Chapter 3.5 --- Laboratory analysis --- p.50 / Chapter 3.5.1 --- Texture --- p.50 / Chapter 3.5.2 --- Reaction pH and conductivity --- p.51 / Chapter 3.5.3 --- Organic carbon of soil and the amended substrates --- p.51 / Chapter 3.5.4 --- Total carbon of coconut meal and compost --- p.51 / Chapter 3.5.5 --- Total Kjeldahl Nitrogen --- p.52 / Chapter 3.5.6 --- Total phosphorus --- p.52 / Chapter 3.5.7 --- Exchangeable A1 and H and total exchangeable acidity --- p.53 / Chapter 3.5.8 --- "Total potassium, sodium，calcium and magnesium" --- p.53 / Chapter 3.5.9 --- Heavy metals --- p.53 / Chapter 3.5.10 --- Exchangeable cations --- p.53 / Chapter 3.5.11 --- Water absorbency of water absorbing polymer --- p.54 / Chapter 3.5.12 --- Water retention capacity --- p.54 / Chapter 3.5.13 --- Mean weight diameter --- p.54 / Chapter 3.6 --- Statistical analysis --- p.55 / Chapter 3.7 --- Results and discussion --- p.55 / Chapter 3.7.1 --- Properties of decomposed granite --- p.55 / Chapter 3.7.2 --- "Properties of water absorbing polymer, coconut meal and compost" --- p.58 / Chapter 3.8 --- Effects of amendment materials on DG --- p.60 / Chapter 3.8.1 --- Penetration resistance --- p.60 / Chapter 3.8.2 --- Soil moisture --- p.64 / Chapter 3.8.3 --- Water release characteristic curves and available water content --- p.69 / Chapter 3.8.4 --- Effect of amendment materials on soil organic carbon --- p.74 / Chapter 3.8.5 --- Relationship between SOC and water release characteristics --- p.77 / Chapter 3.8.6 --- Mean weight diameter --- p.78 / Chapter 3.9 --- Effects of amendment materials on the growth of Schima superba --- p.81 / Chapter 3.9.1 --- Survival rate --- p.81 / Chapter 3.9.2 --- Height and basal diameter increment --- p.84 / Chapter 3.9.3 --- Aboveground biomass --- p.88 / Chapter 3.9.4 --- Chlorophyll florescence --- p.89 / Chapter 3.10 --- Summary --- p.91 / Chapter CHAPTER 4 --- EFFECT OF AMENDMENT MATERIALS ON PHYSICAL PROPERTIES OF DECOMPOSED GRANITE AND THE GROWTH OF CASTANOPSIS FISSA: GREENHOUSE EXPERIMENT II --- p.94 / Chapter 4.1 --- Introduction --- p.94 / Chapter 4.2 --- Materials and methods --- p.95 / Chapter 4.2.1 --- Materials --- p.95 / Chapter 4.2.2 --- Experimental design --- p.96 / Chapter 4.2.3 --- Preparation of growth substrates --- p.96 / Chapter 4.2.5 --- Soil sampling --- p.98 / Chapter 4.2.6 --- Monitoring of soil moisture change and penetration resistance --- p.99 / Chapter 4.2.7 --- Plant growth measurement --- p.100 / Chapter 4.2.8 --- Laboratory analysis --- p.101 / Chapter 4.3 --- Results and discussion --- p.101 / Chapter 4.3.1. --- Properties of DG --- p.101 / Chapter 4.3.2 --- Water absorbency of ALCOSORB® --- p.103 / Chapter 4.3.3 --- Effect of amendment materials on physical properties of DG --- p.103 / Chapter 4.3.4 --- Effect of soil amendment on water release characteristic curves --- p.109 / Chapter 4.3.5 --- Soil evaporation test --- p.113 / Chapter 4.3.6 --- Soil organic carbon --- p.119 / Chapter 4.3.7 --- Mean weight diameter --- p.121 / Chapter 4.3.8 --- Effects of amendment materials on the growth of Castanopsis fissa --- p.123 / Chapter 4.3.8.1 --- Survival rate --- p.123 / Chapter 4.3.8.2 --- Height and basal diameter --- p.126 / Chapter 4.3.8.3 --- Aboveground biomass --- p.132 / Chapter 4.3.8.4 --- Chlorophyll fluorescence --- p.134 / Chapter 4.4 --- Summary --- p.136 / Chapter CHAPTER 5 --- CAN WATER ABSORBING POLYMER BENEFIT QUARRY REHABILITATION IN THE DRY SEASON? --- p.139 / Chapter 5.1 --- Introduction --- p.139 / Chapter 5.2 --- The study area --- p.142 / Chapter 5.2.1 --- The Anderson Road Quarry --- p.142 / Chapter 5.2.2 --- Rehabilitation of Anderson Road Quarry --- p.143 / Chapter 5.3 --- Experimental design --- p.145 / Chapter 5.3.1 --- Site preparation --- p.145 / Chapter 5.3.2 --- Selection of native species for planting --- p.147 / Chapter 5.3.3 --- The planting --- p.148 / Chapter 5.3.4 --- Data logging the growth environment --- p.150 / Chapter 5.3.5 --- Plant growth measurement --- p.150 / Chapter 5.3.6 --- Soil sampling and analysis --- p.151 / Chapter 5.4 --- Statistical analysis --- p.151 / Chapter 5.5 --- Results and discussion --- p.152 / Chapter 5.5.1 --- Properties of decomposed granite in ARQ --- p.152 / Chapter 5.5.2 --- Survival rate --- p.155 / Chapter 5.5.3 --- Height and basal diameter increments --- p.157 / Chapter 5.5.4 --- Major limiting factors for the establishment of seedlings --- p.160 / Chapter 5.5.4.1 --- Drought --- p.160 / Chapter 5.5.4.2 --- Soil erosion caused by rainstorm --- p.163 / Chapter 5.6 --- Summary --- p.165 / Chapter CHAPTER 6 --- EFFECT OF WATER ABSORBING POLYMER ON THE GROWTH OF NATIVE SPECIES IN A RESTORED QUARRY --- p.167 / Chapter 6.1 --- Introduction --- p.167 / Chapter 6.2 --- Study area --- p.168 / Chapter 6.3.2 --- Data logging the growth environment --- p.169 / Chapter 6.3.3 --- Plant growth measurement --- p.169 / Chapter 6.3.4 --- Spatial variation of irrigation water --- p.170 / Chapter 6.4 --- Statistical analysis --- p.170 / Chapter 6.5 --- Results and discussion --- p.170 / Chapter 6.5.1 --- Survival rate --- p.170 / Chapter 6.5.2 --- Height and basal diameter increments --- p.178 / Chapter 6.5.3 --- Growth environment in Anderson Road Quarry --- p.185 / Chapter 6.5.4 --- Weed competition --- p.189 / Chapter 6.6 --- Summary --- p.190 / Chapter CHAPTER 7 --- CONCLUSIONS --- p.191 / Chapter 7.1 --- Summary of major findings --- p.191 / Chapter 7.2 --- Implications of the study --- p.196 / Chapter 7.3 --- Limitations of the study --- p.199 / Chapter 7.4 --- Suggestions for further study --- p.200 / REFERENCES --- p.204 / APPENDICES --- p.222

published_or_final_version / abstract / toc / Geography and Geology / Master / Master of Philosophy

The intention of this work is to provide a deeper understanding of the engineering geological behaviour of granite saprolite and how this affects the engineering of such material, with specific reference to the construction of Injaka Dam in the north eastern portion of South Africa Whilst extensive investigation of weathered granites has been carried out internationally, very little detailed research on the nature of this material is documented locally. The construction of Injaka Dam afforded the opportunity to investigate the saprolite in detail. This study was initially submitted to the Department of Geology and Applied Geology at the University of Natal, Durban (renamed the University of KwaZulu-Natal in 2004) to fulfill the requirement of a Master of Science degree in 200 I. Following this submission, and supported by recommendations made by the external examiners and the project supervisor, it was agreed to upgrade the work and submit this thesis for the degree of Doctor of Philosophy. Intensive chemical weathering of granite at Injaka Dam site has resulted in the formation of thick saprolitic deposits overlying the weathered bedrock. The granite forms part of the 3 075 Ma Nelspruit Suite which has been intersected by the African erosion surface. The extensive, multicyclic period of weathering and erosion that formed this surface has resulted in deep (up to 35 m) chemical weathering of the underlying bedrock in this area. The construction of Injaka Dam on this material necessitated a thorough engineering geological investigation to understand the nature of the weathering and the possible influences it exerts on the engineering behaviour of the saprolite. This was accomplished by analysing the weathering of the granite and relating the effects of these weathering processes and changes to the engineering behaviour of the material. By applying various chemical and mineralogical indices to the weathered granite, the intensity of weathering and related changes could be quantified and compared with the engineering behaviour of the material. This was achieved by applying a series of engineering indices to the material and relating these to the quantified weathering changes. In this way tentative extrapolation of the engineering behaviour of the material could be gained and used to predict engineering performance. The resultant effects of the engineering behaviour of the material on the design and construction of the dam are also discussed. / Thesis (Ph.D.)-University of KwaZulu- Natal, 2004.

La résistance au cisaillement de l'interface béton-roche est un facteur clé dans l'évaluation de la stabilité contre le glissement des barrages en béton construits sur une fondation rocheuse. Alors que plusieurs études ont montré que la rugosité de la surface rocheuse ainsi que la cohésion initiale contribuent à la résistance au cisaillement de l’interface béton-roche, la plupart des recommandations pour l'évaluation de stabilité des barrages proposent des valeurs conventionnelles pour les paramètres mécaniques de cette interface. De plus, la plupart des critères proposés dans la littérature pour déterminer la résistance au cisaillement des joints rugueux sont basés sur des essais de cisaillement direct réalisés sur des joints sans cohésion initiale. Une autre difficulté majeure réside dans la quantification de la rugosité de surface par un paramètre objectif permettant de décrire l'aspect tridimensionnel ainsi que l'anisotropie observée expérimentalement. Dans ce contexte, l'un des principaux objectifs de cette thèse est de mieux comprendre le comportement en cisaillement des joints cohésifs rugueux de béton-granite et de relier la résistance au cisaillement aux paramètres morphologiques de l'interface.En raison de la complexité du comportement en cisaillement des joints cohésifs et du fait que peu d'études ont été réalisées sur des échantillons cohésifs, il a été décidé de réaliser plusieurs campagnes expérimentales sur différents types de rugosité de surface (joints lisses, bouchardés, joints avec aspérités triangulaires et surfaces naturelles). À cette fin, plus de trente essais de cisaillement direct ont été effectués sur des échantillons cohésifs et à trois niveaux de contrainte normale. L'influence de la vitesse de cisaillement sur le comportement mécanique a également été étudiée. Avant la réalisation des essais, un outil morphologique a été développé afin de fournir une quantification objective de la rugosité de surface basée sur des mesures de surface obtenues avec un profilomètre laser.Sur la base des résultats des essais de cisaillement, deux comportements différents ont été observés pour les joints naturelles en fonction de la rugosité de surface et du niveau de la contrainte normale. Ainsi, une expression analytique a été proposée afin de quantifier la contribution des différents modes de rupture à la résistance au cisaillement. Il est montré que cette expression est capable de bien prédire la résistance au cisaillement des joints naturels. De plus, un nouveau paramètre de rugosité a été proposé afin de quantifier la morphologie des joints naturels et de prendre en compte les différents niveaux de rugosité de surface impliqués dans le mécanisme de cisaillement. Ce paramètre s'est avéré être bien corrélé avec la résistance au cisaillement dans le cas des joints cisaillés à une contrainte normale inférieure à 0.6MPa.D'autre part, une modélisation en 3D des essais de cisaillement direct a été proposée par la méthode des éléments finis en incorporant la surface reconstruite des joints obtenue à partir du profilomètre laser. Deux modèles de comportement différents ont été utilisés: un modèle cohésif-frottant pour la phase de pré-pic et une loi de contact pour modéliser la phase résiduelle de cisaillement. Les paramètres mécaniques de l'interface béton-granite ont été obtenus à partir des résultats des campagnes expérimentales sur des échantillons bouchardés. La comparaison entre les résultats numériques et les données expérimentales a montré un bon accord dans la phase résiduelle et une reproduction de la forme globale de la courbe de contrainte de cisaillement. / The shear strength of the concrete-rock interface is a key factor in assessing the stability against sliding of concrete dams founded on rock. While several studies have shown that both surface roughness and the initial cohesion contribute to the shear strength, most of the recommendations for the stability assessment of dams propose conventional values for the mechanical parameters of the dam-foundation interface (i.e. friction angle and cohesion). Moreover, most of the criteria proposed in the literature in order to determine the shear strength of rough joints are based on direct shear tests conducted on joints without initial bonding. Another major difficulty lies in the quantification of surface roughness by means of an objective parameter able to describe the three dimensional aspect of surface roughness as well as the anisotropy observed experimentally. In this context, one of the primary objectives of this thesis is to better understand the shear behavior of bonded rough joints and to relate the shear strength to the morphological parameters of the concrete-rock interface.Due to the complexity of the shear behavior of bonded joints and because few studies have been carried out on cohesive samples, it was decided to perform several experimental campaigns on different types of geometries with an increasingly complex roughness (smooth, bush-hammered, tooth-shaped asperities and natural surfaces). For this purpose, more than thirty direct shear tests were performed on bonded samples at three levels of normal stress. The influence of the shear displacement rate on the shear behavior of joints was also investigated. Prior to the shear tests, a morphological tool was developed in order to provide an objective quantification of surface roughness based on surface measurements obtained with a laser profilometer.Based on the shear test results, two different shear behaviors were observed for the natural joints according to surface roughness and the level of normal stress. Thus, an analytical expression was proposed in order to quantify the contribution from the different modes of failure to the shear strength. It is shown that this expression is able to well predict the shear strength of natural joints. Furthermore, a new roughness parameter was proposed in order to quantify the morphology of natural joints and to account for the different levels of surface roughness involved in the shearing mechanism. This parameter was found to be well correlated with the shear strength of joints sheared at a normal stress less than 0.6MPa.On the other hand, numerical simulations of the direct shear tests were conducted by using a 3D finite element code and by incorporating the reconstructed joint surface obtained from the laser profilometer. Two different models were used: a cohesive-frictional model for the pre-peak phase and a contact law for modeling the residual shear behavior. The mechanical parameters of the concrete-granite interface were obtained from the results of the experimental campaigns on bush-hammered samples. The comparison between the numerical results and the experimental data showed a good agreement in the residual phase. The use of a cohesive-friction model, on the other hand, allowed to mimic the overall shape of the shear stress curve.

Des analyses structurales et pétrophysiques ont été menées dans le Massif de Melechov afin d’étudier les structures contrôlant la porosité, la perméabilité et la conductivité thermique de la roche. La structure du massif a été déterminée sur la base d’un jeu étendu de données incluant des mesures d’ASM et des mesures de terrain des structures ductiles et cassantes. Le système de fractures du massif a été décrit par quatre ensembles de fractures. Les données pétrophysiques mesurées ont servi pour caractériser l’effet de la fracturation et de l’altération sur la géométrie de l’espace poreux et en conséquence sur la perméabilité, la conductivité thermique et les propriétés élastiques du granite. Des propriétés pétrophysiques distinctes ont été identifiées pour du granite intact, du granite sain fracturé ainsi que pour du granite fracturé et altéré contenant des oxydes de fer, de la chlorite et des minéraux argileux. Une étude microstructurale détaillée, combinée à des mesures multi-directionnelles de vitesse des ondes P (VP) à pressions de confinement croissantes a été menée sur un échantillon du granite Lipnice aux schlieren. Les résultats indiquent que l’anisotropie des VP à basses pressions de confinement est contrôlée par des fissures inter-granulaires reliant les clivages sous-parallèles aux schlieren des micas et des feldspaths ainsi que par des fissures intra- ou trans-granulaires dans du quartz sous-parallèles aux fractures d’exfoliation. Une importante fermeture de la porosité de fissures à partir d’une profondeur de 500 m a été interprétée en termes d’élasticité des fissures manifestée par une augmentation rapide des VP avec la pression de confinement croissante. / Structural and petrophysical analysis have been conducted within the Melechov massif with focus on structures controlling the porosity, permeability and thermal conductivity of the rock. The structure of the massif has been constrained based on extensive dataset including AMS and field structural measurements of ductile and brittle structures. The fracture system of the massif has been described by four sets of fractures. The measured petrophysical data have been used to characterize the effect of fracturing and alteration on pore space geometry and in turn on permeability, thermal conductivity and elastic properties of the studied granite. Distinct petrophysical properties have been identified for pristine granite, for fractured fresh granite as well as for fractured granite altered by Fe-oxide, chlorite and clay minerals. A detailed microstructural study combined with multidirectional P-wave velocity measurements at high confining pressure and with AMS analysis has been conducted on a schlieren bearing sample of Lipnice granite. The granite VP anisotropy at low confining pressure was controlled by intergranular cracks interconnecting schlieren-subparallel cleavage cracks in micas and feldspars and by exfoliation fracture-subparallel intra- or trans-granular cracks in cleavage-free quartz. Major closing of the crack porosity linked to the schlieren granite below depth of 500 m has been interpreted in terms of crack compliance reflected by rapid increase in VP with confining pressure.

Dès le début de leur histoire, les Égyptiens ont réussi à maîtriser l'extraction et la taille du granite dans les carrières d'Assouan. Cette roche, réputée pour sa dureté, est particulièrement appréciée au Nouvel Empire où son exploitation prend une importance sans précédent. Les temples de Karnak, lieux de cultes majeurs à cette époque, constituent à ce titre les sites d'érection privilégiés de ces monuments en granite, à l'image des quinze obélisques qui furent, pendant un temps, dressés dans l'enceinte d'Amon. L'utilisation de ce matériau ne se limite cependant pas à ces monolithes ; il a également été employé pour de nombreux éléments d'architecture, de statuaire et de mobilier de culte.S'inscrivant dans une démarche pluridisciplinaire comprenant une approche égyptologique, géologique et technique, cet ouvrage propose une étude sur ces réalisations à travers le prisme du site de Karnak, suffisamment riche pour être, dans une certaine mesure, représentatif de l'utilisation générale du granite dans les temples de l'Égypte ancienne / From the beginning of their history, the Egyptians have acquired an expert knowledge of granite quarrying and cutting in Aswan region. This stone, whose hardness made it famous, has been particularly used during the New Kingdom, when it got an unprecedented importance. The Karnak temples, as major cult spots at that time, have been a privileged site for the erection of monuments made from granite, as reflected by the fifteen obelisks which stood in the Amon enclosure for centuries. Its usage has not been limited to these large monolith pieces ; it has also been shaped in a tremendous amount of architectural elements, statues and objects for worship.Following an interdisciplinary approach combining an egyptological, a geological and a technical study, this work presents an investigation of granite monuments through the prism of the Karnak temples, whose history spreads far enough to be representative, in some way, of the general use of granite in ancient Egypt temples.