field evaluation of permeability of concrete linings and rock masses around underground lined rock caverns by a novel in situ measurement system abstract in this paper we introduce a novel in situ permeability measurement system and present the results of field permeability testing using the developed system using a modular structural design and wide measurement range from low to high permeability the developed system was capable of measuring in situ scale permeabilities of concrete linings construction joints and rock mass around excavated rock caverns such measurements have been extremely limited so far but are essentially required in estimating the sealing performance of underground storage caverns the experimental results of a concrete block model test as well as field permeability measurements of concrete linings and the excavation damaged zone edz around a lined rock cavern lrc in a pilot plant for underground compressed air energy storage caes were presented from these experimental measurements we could verify the effective applicability of the developed system to a wide range of measurement conditions from the low permeability concrete lining matrix to the highly permeable construction joints and fractured rock masses around underground rock storage caverns

field scale acoustic investigation of a damaged anisotropic shale during a gallery excavation in the opalinus clay formation at the mont terri underground rock laboratory the gallery ga08 was excavated in august 2008 to join the end face of the pre existing gallery ga04 the aim of the present work was to perform in situ acoustic experiments to monitor the evolution of the excavation damaged zone edz induced during the gallery construction the end face of ga04 was instrumented with two arrays of acoustic transducers allowing for the active and passive seismic monitoring i e acoustic survey and micro seismicity from the acoustic survey data which required a high energy acoustic source to emit high frequency signals 21 25 31 and 38 khz the rock mass was observed to be anisotropic and heterogeneous at the scale of the experiment p wave velocities were determined to be in average between 3300 m s along a structural bedding plane and 2700 m s at 70 incidence relative to that assuming a transversely isotropic shale formation the p wave velocity dependence versus was modeled using thomsen s weak transverse isotropy model thomsen 1986 36 thomsen s p wave anisotropy parameter was found to be 0 15 and the fifth thomsen s parameter controlling the deviation of the wave front from an ellipsoidal geometry was found to be 0 16 the s wave velocity was estimated along a single direction of aligned receivers and turned out to be around 1560 m s at 30 we also show that the rock mass acts as a frequency filter for acoustic waves related to the rock mass heterogeneities i e the inter bedding structure which induces wave scattering and refraction from the micro seismicity data we identified a large number of micro seismic events mses detected on the acoustic arrays during and following the excavation most of the mses were induced on the excavated face but we also located some mses inside the rock mass itself we show that these events are located close to a major fault which seems to be reactivated by the excavation process

conodont color and textural alteration an index to regional metamorphism contact metamorphism and hydrothermal alteration experimental and field data are used to extend the utility of conodonts as semi quantitative thermal indices into the regimes of regional and contact metamorphism as well as hydrothermal alteration an arrhenius plot of data from induced conodont color alteration by pyrolysis in air at 1 atm was used to generate the geologic temperatures for conodont color alteration indices cai above 300 c that is for cai values of 5 through 8 such cai values occur in very low to medium grade regionally metamorphosed contact metamorphosed and hydrothermally altered rocks the uniformity or variability of cai values within a sample together with conodont texture can help to distinguish grades and environments of metamorphism particularly in metacarbonate sequences induced cai by pyrolysis in a water methane mixture at kbar results in retardation of cai and in a disparate mixture of both low and high cai values within each experimental sample in this system color alteration processes above a cai of 2 to 3 seem to change from predominantly carbonization to predominantly loss of organic matter presumably by oxidation and volatilization of oxides these experiments approximate the type of cai mixture characteristically found in conodonts recovered from hydrothermally altered rocks these data indicate that cai values of 6 to 8 cannot be used to assess precise temperatures of hydrothermally altered rocks but may serve as useful indicators of potential mineralization

hydrochemical disturbances measured in groundwater during the construction and operation of a large scale underground facility in deep crystalline rock in japan changes in the hydrochemical conditions of groundwater were evaluated following the construction of a large scale underground facility at the mizunami underground research laboratory miu japan the facility was constructed to a depth of 500 m in sedimentary and granitic rocks drawdown of the groundwater level in the range of several tens to hundreds of meters was observed up to hundreds of meters away from the shafts during the first ten years of facility construction and operation subsequent changes in groundwater chemistry occurred due to upconing of high salinity groundwater from the deepest part of the shaft and the infiltration of low salinity shallow groundwater we predict that future deep groundwater chemistry in the vicinity of the miu facility will resemble that of the present day shallow groundwater multivariate statistical analysis provides fundamental insights into such a site we found that the extent of hydrochemical variability related to miu construction and operation was dependent on the distance from the facility shafts and galleries and on hydrogeological compartmentalization resulting from lithological boundaries such as permeable conglomerates vs more compact lithological units and other features such as faults or clay layers we conclude that hydrochemical impact assessment of groundwater in low permeability rock is essential prior to the construction of such a facility this should include characterization of hydrogeological structures and compartments to propose suitable location of shafts and galleries

tectonothermal analysis of a major unit of the cantabrian zone the ponga unit variscan belt nw spain the paleothermometric evolution of the ponga unit at the core of the cantabrian zone the arcuate foreland fold and thrust belt of the variscan orogen in nw spain is analyzed using the conodont color alteration index and the kubler index of illite the results indicate that the distribution of the thermal maturity patterns is independent of the stratigraphy and the structure of the unit these include the occurrence of dominant diagenetic values and very low to low grade metamorphism in the southern area the main thermal event is interpreted to be related to hydrothermal fluids ascending through late variscan extensional faults the anomalous high heat flow in the southern sector of the ponga unit is part of a previously identified large band in the cantabrian zone where the common occurrence of low grade metamorphic rocks hydrothermal dolostones and ore mineralizations is related to an extensional orogenic episode that started near the carboniferous permian boundary soon after the closure of the asturian arc

assessment of mineralogical and petrographic factors affecting petro physical properties strength and cracking processes of volcanic rocks abstract microtextural features influence the petrophysical and mechanical properties of rocks including the elastic properties and cracking processes under axial loads volcanic rocks with varying microtextural characteristics and compositions were evaluated to assess the effect of the main constituents mineralogical petrographic and micro structural features on the petrophysical properties elastic properties and strength furthermore detailed analyses were also used to understand the cracking processes under axial loads the analyses of the cracking processes were completed on thin sections obtained from the mechanically tested specimens the results from the quantitative mineralogical and petrographic studies and observations from thin sections revealed that the mineral mass fractions have an effect on the specific gravity and loss on ignition loi values on the other hand unconfined compressive strength ucs and elastic properties are mostly affected by petrographic variables e g mineral content the ucs values tend to decrease with a relative increase in the groundmass with respect to the phenocryst content and vice versa biotite is the only mineral that influences the ucs individually geometric features e g feret s diameter and perimeter of opaque minerals and biotite are determined to be important constituents influencing the young s modulus under axial loads crack propagation is strongly dependent on the proportional distribution of the phenocryst and groundmass it was observed that increasing groundmass content leads to predominantly axial cracks the cracks tend to bend or propagate as a boundary crack when they reach the boundary of an unaltered phenocryst thus axial and shear cracks co exist with increasing amounts of phenocrysts which hinders crack propagation occasionally cracks can penetrate the altered or opaque phenocrysts depending on the degrees of orientation with respect to applied load of the same minerals furthermore the synthesis of the measurements obtained from ucs tests and thin section observations reveals that an increase in the amount of phenocrysts which promote the formation of more shear cracks in addition to axial cracks causes an increase in the radial strain and poisson s ratio the other factors investigated had minor effects on physical and mechanical properties of studied rocks

localization and characterization of cracks in clay rocks using frequency and time domain induced polarization induced polarization ip is a geophysical method that is potentially sensitive to the presence of cracks in porous rocks and therefore to damage we performed time domain and frequency domain ip measurements at the tournemire underground research laboratory url aveyron france in areas where different types of cracks are observed these cracks correspond to both tectonic fractures and new cracks associated with stress release and desiccation resulting from the excavation of a gallery these measurements were performed both in eastern and northern galleries of the test site the eastern gallery was excavated in 1996 while the northern gallery was excavated recently in 2008 this gives us the opportunity to study the electrical characteristics of the excavation damaged zone surrounding the galleries with respect to the age of the excavation longitudinal profiles were performed along the floor of the galleries with 48 cu cuso4 electrodes separated by a distance of 20 cm chargeability and resistivity were inverted using a gauss newton iterative approach assuming an isotropic heterogeneous clay rock material the resulting ip tomograms show a correlation between high values of chargeability and the presence of calcite filled tectonic fractures x ray analysis indicates that the presence of pyrite in these fractures is a potential source of the observed ip signals the cracks associated with the mechanical damage of the formation exhibit low values of chargeability on the same order of magnitude than the chargeability of the clay rock matrix and are therefore hardly observable a smaller ip response associated with the presence of these cracks is observed in the older gallery and this observation is qualitatively related to the desaturation process associated with these cracks in a specific area of one of the galleries the presence of calcareous nodules is observed to be an important source of anomalous chargeability this signature seems to be associated with the presence of pyrite

gas and water flow in an excavation induced fracture network around an underground drift a case study for a radioactive waste repository in clay rock summary the excavation damaged zone edz surrounding a drift and in particular its evolution is being studied for the performance assessment of a radioactive waste underground repository a specific experiment called cdz was designed and implemented in the meuse haute marne underground research laboratory url in france to investigate the edz this experiment is dedicated to study the evolution of the edz hydrogeological properties conductivity and specific storage of the callovo oxfordian claystone under mechanical compression and artificial hydration firstly a loading cycle applied on a drift wall was performed to simulate the compression effect from bentonite swelling in a repository drift bentonite is a clay material to be used to seal drifts and shafts for repository closure purpose gas tests permeability tests with nitrogen and tracer tests with helium were conducted during the first phase of the experiment the results showed that the fracture network within the edz was initially interconnected and opened for gas flow particularly along the drift and then progressively closed with the increasing mechanical stress applied on the drift wall moreover the evolution of the edz after unloading indicated a self sealing process secondly the remaining fracture network was resaturated to demonstrate the ability to self seal of the cox claystone without mechanical loading by conducting from 11 to 15 repetitive hydraulic tests with monitoring of the hydraulic parameters during this hydration process the edz effective transmissivity dropped due to the swelling of the clay materials near the fracture network the hydraulic conductivity evolution was relatively fast during the first few days low conductivities ranging at 10 10 m s were observed after four months conversely the specific storage showed an erratic evolution during the first phase of hydration up to 60 days some uncertainty remains on this parameter due to volumetric strain during the sealing of the fractures the hydration was stopped after one year and cross hole hydraulic tests were performed to determine more accurately the specific storage as well as the hydraulic conductivity at a meter scale all hydraulic conductivity values measured at the injection interval and at the observation intervals were all below 10 10 m s moreover the preferential inter connectivity along the drift disappeared specific storage values at the observation and injection intervals were similar furthermore they were in agreement with the value obtained at the injection interval within the second hydration phase 60 days after starting hydration the graphical abstract synthesizes the evolution of the hydraulic gas conductivity for 8 intervals since the beginning of the cdz experiment the conductivity limit of 10 10 m s corresponds to the lower bound hydraulic definition of the edz and it is demonstrated that edz can be sealed this is a significant result in the demonstration of the long term safety of a repository

faults and fractures in the gallery 04 of the mont terri rock laboratory characterization simulation and application this paper deals with the reconstruction of a fracture network observed in an underground gallery of a tunnel buried in clay stones in switzerland below mont terri the trace maps of the gallery 04 and of the ez g niche of this site have first been digitized and used in various ways to characterize the data the traces have been divided into two groups i e the pre existing faults in the gallery and the fractures of the excavated damaged zone edz in the niche each group has been analyzed individually the number of data for the faults has turned out to be statistically significant while it was very limited for the edz fractures for both cases the major statistical characteristics of the traces have been extracted and a reconstruction procedure developed and tested a full example has been worked out a gallery immersed in a reconstructed fractured porous medium has been meshed and the electrical field created by a dipole at the wall calculated by solving the three dimensional laplace equations in the fractures and in the porous medium

continuum discontinuum analysis of failure mechanisms around unsupported circular excavations in anisotropic clay shales abstract the stability of circular excavations in clay shales is a key issue in the drilling and tunnelling industries as well as in the field of deep geological waste storage a large body of experimental evidence indicates that the damaged zone around these cavities is influenced by strong mechanical anisotropy induced by the layered material structure the vast majority of numerical models adopted to date to analyse the stability of openings in layered rocks have been based on continuum mechanics principles using classic shear failure theory for elasto plastic materials however a number of experimental observations demonstrate that clay shales may fail in a brittle manner under low confinement conditions such as those characterizing the near field of the excavation therefore an alternative numerical approach based on non linear fracture mechanics principles and the discrete element method is adopted to gain new insight into the failure process of this class of geomaterials in order to account for the influence of clay shale microstructure on its mechanical behaviour a newly developed approach to capture the anisotropy of strength is proposed with this numerical approach the cohesive strength parameters of the fracture model are assumed to be a function of the relative orientation between the element bonds and the layering orientation the effectiveness of the numerical technique is quantitatively demonstrated by simulating standard rock mechanics tests on an indurated claystone namely opalinus clay emergent strength and deformation properties together with the simulated fracture mechanisms are shown to be in good agreement with experimental observations the modelling technique is then applied to the simulation of the excavation damaged zone edz around a circular tunnel in horizontally bedded opalinus clay the simulated fracturing process is mainly discussed in the context of the damage mechanisms observed at the mont terri url furthermore the influence of in situ stress on resulting edz geometry is analysed together with possible implications for ground support and tunnel constructability modelling results highlight the importance of shear strength mobilization along bedding planes in controlling the edz formation process in particular slippage of bedding planes is shown to cause rock mass deconfinement which in turn promotes brittle failure processes in the form of spalling the numerical technique is currently limited to two dimensional analyses without any thermo hydro mechanical coupling

geothermal palaeogradients and metamorphic zonation from the conodont colour alteration index cai the conodont colour alteration index cal is potentially does not exist there are areas where cal and ki values are valuable in thermal history investigations but there are notably consistent for the anchizone boundaries however problems in its use an approach is proposed herein to anomalous correlations between cal and ki values have also overcome the problem of establishing reliable geothermal been found in some areas a cal anchizone or ancaizone is palaeogradients in areas with burial metamorphism based on defined in order to enable cal values to be used independently knowledge of the stratigraphic succession thickness the to establish a metamorphic zonation boundaries of chronostratigraphic units and the age and duration of deformation episodes although also problematical terra nova 13 79 83 2001 that a correlation between cal and kubler index ki values

calibration of conodont color alteration using color image analysis a set of 40 polished sections of silurian and devonian conodonts with color alteration indices ranging from 1 0 to 8 0 was examined using color image analysis the color composition of each conodont specimen was determined by measuring the intensities of the red green and blue color components on several carefully selected areas the data were evaluated using nested analysis of variance the observed variance can be attributed to three different sources of error within the studied conodont population the variance due to rank amounts to an average 90 the variance due to taxonomic differences or type of conodont element is about 3 and thus of minor importance the heterogeneity within single specimens amounts to 6 and is also a minor source of variance the application of color image analysis helps characterize samples of different rank but similar optical properties color image analysis helps reduce the subjectivity of conodont color alteration studies

spectral reflectance of conodonts a step toward quantitative color alteration and thermal maturity indexes changes in the color of conodonts have long been used to assess thermal maturity color is a subjective measure and color changes in conodonts are related to a subjective scale the conodont alteration index or cai in this paper we propose a simple nondestructive method for objectively determining cai and relating cai to thermal maturity the spectral reflectance of conodonts src the diffuse reflectance of about 30 large conodont fragments arranged on a barium sulfate slide was determined with a total reflectance spectrophotometer in the wavelength range of 300 850 nm by examining conodonts that ranged from a cai of 1 to a cai of 6 we found that the average slope of the reflectance curve from 550 to 800 nm is a good proxy for cai a second order regression equatio estimates cai from this slope with high accuracy correlation coefficient 0 99 these estimates appear most accurate for a cai of 1 to a cai of 4 where the slopes change most rapidly but give reasonable results up to a cai of 6 based on the results of our analysis of two samples with known thermal maturities from the valles caldera region of new mexico we propose a preliminary relationship among src slope cai and in situ alteration temperature

thermal maturity of carbonaceous material in conodonts and the color alteration index independently identifying maximum temperature with raman spectroscopy abstract the color alteration index cai of conodont specimens is commonly used for identifying the maximum temperature to which units of sedimentary rock particularly carbonates have been heated observable color variations in these fossils are thought to be a result of the thermally induced structural evolution of organic carbonaceous matter cm such temperature history information is extremely valuable for applications in hydrocarbon exploration as well as for constraining other temperature related geological processes in sedimentary systems however the identification of cai depends on the qualitative visual assessment of color which along with a host of other potential complications may yield inaccurate determinations of maximum temperature raman spectroscopy allows thermally induced structural changes in cm to be quantified and it has been used to estimate the thermal maturity in metasedimentary rocks for almost two decades here we use raman spectroscopy of carbonaceous material rscm in conodont specimens and their mississippian to upper triassic host rocks from british columbia canada to estimate maximum temperatures based on the transformation structural reorganization of disordered carbon to graphite this study demonstrates that the maximum temperatures experienced by conodont specimens as calculated from rscm using the iterative fitting of raman spectra ifors technique correlate well with cai but lie outside the suggested ranges in some instances this may be due to complex thermal histories of these conodont specimens or the influence of diagenetic alteration not thermal histories on conodont color we recommend the application of raman spectroscopic analyses of cm in conodonts and their host rocks to obtain more confident accurate and precise estimations of maximum temperature that are independent of cai

in situ behaviour of a stiff layered clay subject to thermal loading observations and interpretation the paper presents an interpretation of an in situ heating test carried out on opalinus clay in the mont terri underground laboratory opalinus clay is a stiff strongly bedded mesozoic clay of marine origin when subjected to thermal loading saturated stiff clays exhibit a strong pore pressure response that significantly affects the hydraulic and mechanical behaviour of the material the observations gathered in the in situ test have provided an opportunity to examine the integrated thermo hydro mechanical thm response of this sedimentary clay coupled thm numerical analyses have been carried out to provide a structured framework for interpretation and to enhance understanding of thm clay behaviour numerical analyses have been based on a coupled theoretical formulation that incorporates a constitutive law especially developed for this type of material the law includes degradation of bonding by damage by performing three dimensional computations it has been possible to incorporate anisotropy of m

investigation of the damage induced by desiccation and heating of tournemire argillite using digital image correlation abstract a set of samples taken from the tournemire site was submitted to a desaturation process in an oven at different temperature levels of 40 c 50 c 80 c 105 c 150 c and 200 c the resulting hydro mechanical behavior was studied by measuring the strain fields obtained from a non invasive method called digital image correlation dic after a few dozens of minutes from the beginning of the thermal loading the induced strains concentrated into narrow zones or bands indicating strain localization these narrow zones were precursors of desiccation cracks which were also detected from the first temperature level at 40 c or 50 c our results confirmed the fundamental role of the textural and sedimentological heterogeneities in the cracking process desiccation cracks appeared at the interface between clay matrix and macroscopic non clayey heterogeneity i e calcite concretion and were predominantly parallel to the bedding planes at a temperature level of 105 c the desiccation cracks were no longer observable and seemed to close this healing process was interpreted as a thermally driven process when the shrinkage limit was reached a thermal dilation of the water clay minerals system occurred leading to a gradual closure of desiccation cracks

geological and hydraulic characterisation of the excavation disturbed zone in the opalinus clay of the mont terri rock laboratory abstract the fracture network in the excavation disturbed zone edz of an argillaceous formation the opalinus clay in the mont terri rock laboratory in northwest switzerland is characterised using structural and hydrogeological techniques sampling of unloading fractures is done by analysing resin injected overcores taken from the edz resulting in a structural data set of fracture orientations frequencies and extent of the edz these parameters are derived in tunnel sections which were excavated by blasting pneumatic hammering and road header techniques pneumatic and hydrogeological tests are subsequently carried out to derive hydraulic parameters such as permeability and transmissivity distributions of the fracture network synthesis of the structural and hydrogeological data led to a conceptual model of the edz in the mont terri rock laboratory which is defined by a 2 m plastically deformed zone around the tunnel this plastic zone is further divided into an inner 1 m zone consisting of an air filled fracture network and an outer zone with mostly saturated and isolated fractures transmissivities in the inner zone are orders of magnitude higher than those of the undisturbed opalinus clay finally a methodology is proposed for the structural and hydrogeological characterisation of the edz this methodology is not site specific and is thus applicable at any argillaceous underground facility

anisotropy of experimentally compressed kaolinite illite quartz mixtures the anisotropy of physical properties is a well known characteristic of many clay bearing rocks this anisotropy has important implications for elastic properties of rocks and must be considered in seismic modeling preferred orientation of clay minerals is an important factor causing anisotropy in clay bearing rocks such as shales and mudstones that are the main cap rocksofoilreservoirs thepreferredorientationofclaysdepends mostly on the amount of clays and the degree of compaction to studytheeffectoftheseparameters wepreparedseveralsamples compressingattwoeffectiveverticalstressesamixtureofclays illite and kaolinite and quartz silt with different clay quartz ratios the preferred orientation of the phases was quantified with rietveld analysis on synchrotron hard x ray images pole figures for kaolinite and illite display a preferred orientation of clay platelets perpendicular to the compaction direction increasing in strength with clay content and compaction pressure quartz particles have a random orientation distribution aggregate elastic properties can be estimated by averaging the singlecrystal properties over the orientation distribution obtained from the diffraction data analysis calculated p wave velocity anisotropy ranges from 0 pure quartz sample to 44 pure clay sample highly compacted but calculated velocities are much higher than measured velocities this is attributed to uncertainties about single crystal elastic properties and oriented micropores and limited grain contacts that are not accounted for in themodel inthiswork wepresentaneffectivemethodtoobtain quantitative data helping to evaluate the role of clay percentage and compaction pressure on the anisotropy of elastic properties ofclay bearingrocks

development of coupled shear flow visualization apparatus and data analysis abstract a new type apparatus for shear flow coupling test named coupled shear flow visualization apparatus was developed to investigate the hydromechanical behavior and the fracturing process of intact soft sedimentary rock with this apparatus it is possible to simultaneously carry out direct shear test and constant head flow test and also to observe specimen surface during the experiment under controlled shear load normal load flow rate and shear displacement can be obtained as raw data moreover fracture area and fracture apertures can be estimated using image processing techniques the shear and normal stress capacities of load cells are 4 08 mpa and 3 33 mpa respectively the measurable maximum permeability of apparatus is about 5 80 10 3 cm s under a hydraulic gradient of 40 cm cm according to the observation of visible fractures on specimen surface the fractures were not completely propagated at the peak of shear stress the developed testing method with image processing techniques enabled us to analyze the relationships between fracture flow rate hydraulic aperture and two fracture apertures defined in this study

seismic investigation of the excavation damaged zone in opalinus clay a mini sonic borehole probe was used to investigate the excavation damaged zone edz around an underground opening in the opalinus clay in the mont terri rock laboratory in switzerland the edz could be determined by using seismic parameters as interval velocities and amplitudes of first arrivals derived from measurements in eight radial drilled boreholes the extent of the edz is about 1 m but varies between 0 6 and 2 2 m

velocity survey of an excavation damaged zone influence of excavation and reloading during gallery excavation regardless of the method chosen the surrounding rock is mechanically disturbed in the case of a an underground disposal for ultimate chemical wastes or for radioactive wastes such mechanical changes to the rock state can create preferential pathways for releasing material from the waste inside the excavation e g chemical waste gases brine or dissolved radionuclide up to the biosphere the mechanical characterization of this disturbed zone is thus essential to assessing the rock capacity necessary for constituting an impermeable geological rock barrier the key to this effort lies in determining the nature extent and change to this disturbed zone the survey by means of ultrasonic wave analysis is particularly appropriate for these purposes since it provides information on the zone left undisturbed by the boreholes the main objective behind this paper is to describe a recent in situ experiment called ez a conducted in opalinus clay at the mont terri rock laboratory in switzerland bossart et al 2002 this in situ experimental campaign successfully studied the possibility of improving the properties of rocks forming the edz excavation damaged zone the experiments consisted of three stages the first entailed locating the edz from the existence of gallery ez a at the mont terri laboratory the second traced evolution of the edz arising from a 20 cm thick and 150 cm deep slot excavation at the ez a gallery floor and the third stage focused on p wave velocity evolution surrounding the slot during a pressure loading performed at the slot walls which serves to characterize edz evolution in the slot these three stages were carried out by applying the seismic technique of tomography and then recording wave propagations during the excavation and reloading stages the velocity before and after slot excavation reloading along with the survey during slot excavation showed a decrease in p wave velocity underneath the slot floor down to a 0 2 m depth reloading clearly improves p wave propagation along the sidewall and slightly decreases these same characteristics under the slot

a new approach to quantify the anisotropy of hydromechanical strains in clay rock at the gallery scale abstract we describe a new method to quantify the anisotropy ratio of hydric strains acquired at the gallery scale and over a period of at least one year this method was applied in the context of an investigation conducted on a gallery front of the experimental station of tournemire france which was subjected to a natural seasonal cycle our approach was based primarily on a new algorithm for digital image correlation known as h dic which can accurately locate desiccation cracks and extract fifteen uncracked blocks with quantified sub vertical and sub horizontal strains the values of the anisotropy ratio of hydric strains i e the ratio of the sub vertical strains to the sub horizontal strains or the ratio of the strains perpendicular to the bedding to those parallel to the bedding are in the range of 2 84 5 35 with a mean value close to 4 2 the anisotropy ratio for the hydric strains appears to be independent of the natural cycle i e hygrometry present in the gallery this observation is supported by a theoretical estimation of this anisotropy ratio which suggests that the poroelastic parameters of clay rock are insensitive to climatic changes or that theirs evolutions roughly cancel each other out with regard to geometrical patterns area width height aspect ratio and orientation calculated for the uncracked blocks the anisotropy ratio of the hydric strains does not depend on the area of these uncracked blocks moreover a literature review shows that the values of the anisotropy ratio for the hydric strains determined in this study are significantly larger than those obtained at the laboratory scale on undamaged samples or estimated from a theoretical relationship established in a poroelastic framework these comparisons strongly suggest that damage to clay rock existing on the gallery front contributes to a significant increase in the anisotropy ratio of the hydric strains

well integrity assessment under temperature and pressure stresses by a 1 1 scale wellbore experiment a new in situ experiment is proposed for observing and understanding well integrity evolution potentially due to changes that could occur during a well lifetime the focus is put on temperature and pressure stresses a small section of a well is reproduced at scale 1 1 in the opalinus clay formation representative of a low permeable caprock formation in mont terri underground rock laboratory switzerland the well system behavior is characterized over time both by performing hydro tests to quantify the hydraulic properties of the well and their evolution and sampling the fluids to monitor the chemical composition and its changes this paper presents the well integrity assessment under different imposed temperature 17 52 c and pressure 10 28 bar conditions the results obtained in this study confirm the ability of the chosen design and observation scale to estimate the evolution of the well integrity over time the characteristics of the flow along the well system and the reasons of the observed evolution in particular the estimated effective well permeability is higher than cement or caprock intrinsic permeability which suggest preferential flow pathways at interfaces especially at the very beginning of the experiment the significant variations of the effective well permeability observed after setting pressure and temperature stresses indicate that operations could influence well integrity in similar proportions than the cementing process

in situ seismic measurements in claystone at tournemire france compressional and shear wave seismic measurements were performed in an old railway tunnel and in galleries excavated in a 250 m thick toarcian claystone formation in the tournemire experimental station france three component 3c geophones and three orthogonal orientations of the vibroseismic force source were used additionally vertical seismic profiling vsp measurements were recorded with a 3c borehole geophone a hydrophone and a microphone in a 159 m deep borehole id180 in the tunnel the seismic data show that toarcian claystone has strong transverse isotropy ti with a vertical symmetry axis the qp sh and qsv wave propagation velocities in horizontal directions the plane of isotropy of the ti medium are measured as 3550 1850 and 1290 m s 1 respectively the zero offset vsp reveals that only one shear wave propagates in the vertical depth direction and the p and s wave velocities are 3100 and 1375 m s 1 respectively four elastic moduli of the ti medium are determined from the seismic velocities and from the bulk density of 2 53 g cm 3 c11 31 9 gpa c33 24 3 gpa c44 4 5 gpa and c66 8 7 gpa a walkaway vsp with the borehole geophone at 50 m depth in borehole id180 and shot points in the galleries leads to oblique seismic ray paths which allow us to determine the fifth elastic modulus of the ti medium to c13 16 gpa the tube wave recorded by a hydrophone in the water filled lower part of the borehole propagates with 1350 m s 1 which confirms the estimate of the elastic constant c66 the analysis of body wave and surface wave data from a seismic experiment in galerie est shows reflections from several fracture zones in the gallery floor the thickness of the excavation damaged zone edz in the floor of galerie est is estimated to 0 7 m the authors 2014 published by oxford university press on behalf of the royal astronomical society

hydrologic issues associated with nuclear waste repositories significant progress in hydrology especially in subsurface flow and solute transport has been made over the last 35 years because of sustained interest in underground nuclear waste repositories the present paper provides an overview of the key hydrologic issues involved and to highlight advances in their understanding and treatment because of these efforts the focus is not on the development of radioactive waste repositories and their safety assessment but instead on the advances in hydrologic science that have emerged from such studies work and results associated with three rock types which are being considered to host the repositories are reviewed with a different emphasis for each rock type the first rock type is fractured crystalline rock for which the discussion will be mainly on flow and transport in saturated fractured rock the second rock type is unsaturated tuff for which the emphasis will be on flow from the shallow subsurface through the unsaturated zone to the repository the third rock type is clay rich formations whose permeability is very low in an undisturbed state in this case the emphasis will be on hydrologic issues that arise from mechanical and thermal disturbances i e on the relevant coupled thermo hydro mechanical processes the extensive research results especially those from multiyear large scale underground research laboratory investigations represent a rich body of information and data that can form the basis for further development in the related areas of hydrologic research

in situ monitoring of tunnel deformation evolutions from auxiliary tunnel in deep mine abstract deformation caused by excavation is of great effects on tunnel stability and tunnel support design monitoring using instruments that are installed in place within the examined tunnel cannot record a large amount of surrounding rock deformation that usually takes place ahead and close to the tunnel face for this important reason the overall deformation process was observed using instruments installed prior to excavation from auxiliary tunnel in a 900 m deep coal mine tunnel two monitoring methods i e multipoint extensometers and wave velocity tomography were used at two monitoring sections with different rock lithology the results showed that a large amount of deformation at both monitoring sections had already been occurred when the excavation face passed the monitoring sections at a very small distance the size of the plastic zone at monitoring section 1 is identified as 1 8 m 0 36 d d denotes the diameter of the examined tunnel and the velocities within this zone decreased from 4 5 km s to 2 km s the primary deformation was generated in a distance from 0 8 d ahead the excavation face to 2 3 d behind the excavation face the induced deformation was also observed after the primary deformation period and some additional deformation was still occurred in the plastic zone although the size of plastic zone remains constant the displacements and p wave velocities at the two monitoring sections showed little differences

an unsaturated hydro mechanical modelling of two in situ experiments in callovo oxfordian argillite abstract the unsaturated behaviour of callovo oxfordian argillite is investigated through the modelling of 2 in situ experiments the first test studies the influence of ventilation in a gallery on the hydro mechanical behaviour of the rock mass the second test consists in a gas injection in the rock mass from an experimental borehole a hydro mechanical model is described and used in the modelling of the experiments a review of the main hydro mechanical parameters of argillite is presented the numerical results highlight the need of a flow boundary condition reproducing the fluid transfers between the surroundings and the rock mass the influence of dissolved gas on the compressibility of the liquid phase is also emphasised

non invasive detection of fractures fracture zones and rock damage in a hard rock excavation experience from the aspo hard rock laboratory in sweden abstract a key requirement for licensing of the construction of underground repositories for nuclear waste is the demonstrated capability to verify design assumptions involving the presence and extent of the excavation damage zone around tunnels shafts emplacement holes and caverns as part of ongoing work to select and refine key technologies and techniques towards this end geophysical surveys were performed at two locations within the aspo hard rock laboratory in sweden earth resistivity res induced polarization ip and ground penetrating radar gpr data were collected using a variety of survey parameters light detection and ranging lidar data were collected as a reference for surface structures surface topography and site geology based on an analysis of the data models for the highly damaged zone hdz and excavation damage zone edz at both sites were developed the hdz was found to be approximately 5 to 10 cm in thickness and the edz was found to extend between 15 and 35 cm below the excavation surface two dimensional 2d res profiling generated the most reliable assessment of the hdz whereas chargeability data and gpr data were more useful in the estimation of the edz dimensions

hierarchies of overpressure retardation of organic matter maturation case studies from petroleum basins in china the effects of overpressure on different aspects of organic matter maturation have been examined in three basins using multiple parameters overpressure in the yinggehai basin has retarded kerogen maturation hydrocarbon generation and thermal cracking of long chain normal hydrocarbons as well as evolution of isoprenoid hydrocarbons overpressure in the dongpu depression bohai bay basin seems to have retarded the maturation of bulk kerogens reflected by rock eval tmax the thermal cracking of long chain normal hydrocarbons and the evolution of isoprenoid hydrocarbons but seems to have had no detectable effects on vitrinite reflectance overpressure in the qiongdongnan basin has had no detectable retardation effects on all aspects of organic matter maturation the observed phenomena suggest differential retardation of organic matter maturation that is different organic matter maturation reactions and different maturity parameters have been retarded by overpressure to different degrees in the same overpressured system and four hierarchies of overpressure retardation hierarchy i retardation is defined as the state where the overpressure has retarded all aspects of organic matter maturation and is proposed to have been caused by the combination of high formation pressure and excess pressure a high water organic matter ratio and strong retention of reaction products in an early developed strong persistent overpressured system hierarchy ii retardation refers to the case in which all aspects of organic matter maturation except the maturation of hydrogen poor kerogens especially vitrinite have been retarded and seem to have been caused by early developed moderate to strong persistent overpressure hierarchy iii retardation refers to the situation where overpressure has retarded only the thermal cracking of liquid hydrocarbons but has had no detectable effect on the maturation of both hydrogen rich and hydrogen poor kerogens and is proposed to have been caused by moderate to strong persistent overpressures that began to develop around peak oil generation hierarchy iv retardation is defined as the situation where overpressure has had no detectable retardation on all aspects of organic matter maturation and may have been caused by cases wherein the overpressure developed too late the intensity of the overpressure was too low the duration of the overpressure was too short or overpressured fluids had been expelled frequently resulting from both the diversities of organic matter maturation reactions and the complexities of overpressure generation and development the hierarchies of overpressure retardation in different basins may be quite different and it is necessary to use multiple parameters to understand the evolution of the petroleum systems in overpressured basins

numerical and experimental investigation of blasting damage control of a high rock slope in a deep valley abstract the disturbance of a rock mass due to blasting impact and stress redistribution can significantly affect the overall performance of an excavation crack formation during presplit blasting was analyzed with a mathematical model considering the in situ stress the results clearly indicate that the in situ stress can inhibit crack formation the linear density of the explosive and blast hole spacing should be adjusted to improve crack formation the damage distribution produced by different blasting approaches was reproduced with a numerical simulation based on the secondary development of ls dyna the results demonstrate that the damage control effects of conventional presplit blasting or smooth blasting under in situ stress are not ideal owing to the combination of blasting load and stress redistribution crack formation at the lateral sides was inhibited during presplit blasting while the middle side could not be sufficiently broken during smooth blasting an optimized method of presplit smooth blasting was proposed and verified with numerical simulations finally based on excavation of the baihetan high rock slope a comparison of the conventional and optimized approaches was conducted with sonic wave tests and roughness monitoring the results demonstrate that the presplit smooth blasting approach inherits the advantages of both presplit and smooth blasting and could significantly improve contour control effects

tectonothermal evolution of a major thrust system the esla valsurbio unit cantabrian zone nw spain the tectonothermal evolution of a unit in the foreland fold and thrust belt of the iberian massif is established using the conodont colour alteration index cai the unit consists of two parts with different tectonothermal histories the esla nappe region and the valsurbio region separated by a synorogenic carboniferous basin guardo valderrueda basin the esla nappe region evolved in diacaizonal conditions corresponding to the diagenetic conditions of the pelites whose palaeotemperatures were controlled by rock burial maximum values were reached before the emplacement of the thrust nappes so tectonic superimposition is not registered by the cai overburial due to the emplacement of the thrust units was prevented by simultaneous intense erosion the geothermal gradient obtained for burial was c 35 c km 1 and the temperature reached by the older cambrian rocks was c 210 230 c the valsurbio region was affected by an extensional tectonothermal post orogenic event that gave rise to metamorphism with ancaizonal or epicaizonal conditions corresponding to anchizone or epizone of the pelites the most common maximum palaeotemperatures reached in this event fall within the range 305 415 c although higher palaeotemperatures could be reached locally as a consequence of contact metamorphism this event gave rise to subhorizontal cleavage that cuts the main variscan folds coal rank data indicate an increase in maximum palaeotemperatures eastwards from the esla nappe region to the valsurbio region through the guardo valderrueda basin

review and update of the applications of organic petrology part 1 geological applications abstract organic petrology developed as coal petrology at the beginning of the 20th century dedicated mainly to the study of coals because of their utilization in industry coal petrology was then considered a branch of coal science later with the development of specialized nomenclature classification of coal components and the standardization and improvement of analytical microscopical methods this discipline expanded in interests and name becoming organic petrology organic petrology carries a broader context being as well a tool applied in the study of dispersed organic matter in sedimentary rocks due to its importance in exploration for fossil fuel resources at present organic petrology is a discipline widely recognized for its role in fundamental and applied research with respect to both coal utilization and in geosciences throughout the 20th century several important monographs have been published on the discipline of organic petrology including stach s textbook of coal petrology 1st edition 1935 2nd 1975 3rd 1982 updated as the more general organic petrology by taylor et al 1998 more recently the text applied coal petrology the role of petrology in coal utilization was published by suarez ruiz and crelling 2008 this review is the first in a two part review series that describes and updates the role of organic petrology in geosciences a second part complementing this one and focused on the applications of organic petrology to other scientific fields will follow

criteria for rapid sliding ii thermo hydro mechanical and scale effects in vaiont case abstract thermally induced excess pore pressures have been included into a two wedge evolutive model of vaiont landslide the problem requires the solution of a system of four coupled balance equations for the shear bands and the surrounding rock as well as the joint equation of motion of the entire slide the model predicts the high velocities observed and is consistent with other data slide geometry residual strength and conditions on the sliding surface the interpretation of a sensitivity analysis suggests that there exists a threshold permeability band in the range 10 8 to 10 10 m s which separates potentially fast motions from slow motions this conclusion is maintained if the scale of the landslide is reduced

conodont palaeothermometry of contact metamorphism in middle ordovician rocks from the precordillera of western argentina the yerba loca formation middle upper ordovician exposed in the western precordillera san juan argentina is made up of clastic carbonate turbidites and basic ultrabasic rocks it is affected by regional siluro devonian very low grade metamorphism that locally reaches greenschist facies at ancaucha creek 45 conodont samples were taken from two sections that include 30 to 50 m thick sills in order to analyse the thermal alteration patterns produced by these intrusive bodies conodont colour alteration index cai is contrasted with optical petrography and x ray diffraction analyses of clay minerals the intrusions are dated as post darriwilian da2 as determined by conodont biostratigraphy of the host rock which indicates the paroistodus horridus subzone of the lenodus variabilis zone the distribution of cai values defines a thermal aureole of about 2 5 times intrusion thickness that prevailed over the later very low grade metamorphism metasomatism at ancaucha creek is recorded by cai values of 4 to 7 particularly restricted to a few layers close to the intrusions as indicated by conodont textures and rock fabric one dimensional thermal computer simulation conforms to empirical data indicating temperatures greater than 600 c for the contact zone although it points out slightly narrower thermal aureoles the clay mineral assemblage of most of the analysed samples chlorite illite smectite and i s mixed layers is complex and probably derives from several superimposed processes thus representing non equilibrium assemblages in turn ki values 0 27 0 32 indicate anchizone metamorphism in agreement with regional cai values of 4 consequently the occurrence of smectite and i s probably resulted from retrograde diagenesis processes

the early paleozoic evolution of the argentine precordillera as a laurentian rifted drifted and collided terrane a geodynamic model paleontologic and stratigraphic evidence points to the early paleozoic precordilleran terrane of western argentina as being the conjugate rift pair of the appalachians stratigraphic similarities of the cambrian and early arenig carbonate series and very strong affinities among trilobite conodont and brachiopod faunas show their close relationship the most probable provenance areas are the appalachian ouachita rifted margin and the newfoundland appalachians although the former fits better with geometric and drifting paths suggested by faunal affinities increasing celtic and baltic brachiopod genera and divergent stratigraphy since the arenig indicate the drifting of the precordilleran terrane collisional foredeeps developed on collapsed former platform carbonates as flexural subsidence progressed the collision of the precordillera with western gondwana occurred during the mid llanvirn to llandeilo a magmatic arc related to eastward subduction present coordinates was active in the famatina range east of the precordillera this region of celtic affinity shows faunal exchange with the precordilleran terrane since the late arenig and may represent accreted intra iapetus volcanic island arc complexes the rifting and drifting stages are consistent with paleoclimatic and paleomagnetic data that show the migration of the precordilleran terrane from periequatorial to peripolar latitudes between the cambrian and latest ordovician the deep ocean to the west of the precordillera started to close by the late ordovician with the eastward drift of the chilenian terrane absence of volcanic or pyroclastic arc derived rocks in the precordillera indicate west dipping subduction as chilenia approached the continental margin a new forebulge was established on the former collided precordilleran terrane developing an erosional unconformity in central precordillera talacasto tambolar arch a gondwanic signature was fully developed by the middle silurian when the malvinokaffric clarkeia fauna flourished before then the late ordovician glacial record and associated hirnantia fauna were the first clear tie to gondwana during the silurian the marginal basin behaved as a foreland with lithosphere rheology and eustasy governing the sequence stratigraphy wrench faulting along its eastern boundary displaced the precordillera toward the south continued shortening during closure with the chilenian terrane in the mid devonian produced thrust loading of the basin and generated a thick graywacke succession final accretion of chilenia late devonian generated a regional angular unconformity between the lower and upper paleozoic new eastward subduction was initiated west of the accreted chilenian terrane during the late permian triassic as indicated by the choiyoi volcanic complex which presently outcrops in the frontal cordillera

anomalies of noble gases and self potential associated with fractures and fluid dynamics in a horizontal borehole mont terri underground rock laboratory abstract before the excavation of the new gallery ga08 in the mont terri underground rock laboratory switzerland which joined the existing gallery ga04 in 2008 the end face of gallery ga04 was instrumented in 2007 to characterize the evolution of the rock mass with geochemical and geophysical methods the noble gas content of a 12 m long horizontal borehole evidenced that desaturation processes occurred in the first 2 m where pre existing fractures accommodated the stress change during excavation of gallery ga04 four years before these first 2 m are associated with the so called excavation damaged zone edz as an inflow of pore water was observed in this borehole few weeks after its drilling continuous self potential sp measurements were performed to characterize its dynamics after the drilling of new sub horizontal boreholes in the end face strong localized variations of sp occurred the comparison with the geological features of the rock mass suggests that these dynamic anomalies have to be associated with fluid circulation in pre existing tectonic fractures that were primarily reactivated by the excavation of the gallery ga04 and subsequently by the drilling operations

the mont terri rock laboratory a new international research project in a mesozoic shale formation in switzerland abstract in many countries argillaceous formations are being considered as potential host rocks for repositories of radioactive waste therefore in 1995 several organisations decided to start an international research project in the reconnaissance gallery of the mont terri motorway tunnel in north western switzerland in a mesozoic shale formation the opalinus clay aalenian this project is under the patronage of the swiss national hydrological and geological survey the following organisations are also partners in the project andra and ipsn france bgr germany enresa spain nagra switzerland jnc and obayashi japan sckcen belgium the aims of the project are to analyse the hydrogeological geochemical and rock mechanical properties of an argillaceous formation the changes of these properties induced by the excavation of galleries and to evaluate and improve appropriate investigation techniques in january 1996 eight niches were excavated for the project and 15 experiments were started in boreholes of no more than 30 m in length in the winter of 1997 1998 a new research gallery was excavated to host further experiments different excavation drilling and investigation techniques have been tested and improved significant results of the different experiments are already available some of those dealing with hydrochemistry porewater pressure measurements and the evolution of the excavation disturbed zone edz are reported in this paper

numerical simulation on excavation induced damage of rock under quasi static unloading and dynamic disturbance during the excavation of underground opening the rock may experience a complex loading path that includes the highly confined compression before excavation unloading of confining stress and further disturbance of dynamic loading after excavation by using rock failure process analysis for dynamics rfpa dynamics the failure of rock sequentially subjected to this complex loading path is numerically simulated in order to examine the rock failure mechanism induced by excavation the rfpa dynamics is firstly used to reproduce the failure of rock under confined compression followed by unloading of confining pressure and it is validated against with the existing experimental observation then the failure characteristics of rock specimen sequentially subjected to the quasi static triaxial loading unloading of confining pressure and dynamic disturbance are numerically simulated where the effect of magnitude of axial loading and confining pressure and duration and amplitude of the dynamic disturbance on the final failure patterns of rock are examined the numerical results indicate that the arc shaped spalling damage zone is prone to develop with the increase in the axial pressure and lateral pressure coefficient as for the effect of dynamic disturbance the contribution of duration and amplitude of dynamic disturbance on the energy input are similar where the area of damage zone increases with the energy input into the rock specimen in this regard the area of the damage zone is influenced by both the magnitude of in situ stress and waveform of dynamic disturbance this study denotes that it is of great significance to trace the complex loading path induced by excavation in order to capture the rock failure mechanism induced by underground excavation

influence of tectonic shears on tunnel induced fracturing abstract the opalinus clay is currently under investigation as a potential host rock for deep geological disposal of nuclear waste at the mont terri rock laboratory in switzerland bedding in the opalinus clay at mont terri is ubiquitous and highly persistent leading to mechanical transverse isotropy adding to the complexity at the rock laboratory is the frequent occurrence of small scale tectonic shears this paper explores the influences of millimetre thick tectonic shears and bedding on the development of induced fractures mapped in the ez b field experiment at the research facility a series of numerical analyses were carried out by increasing the geological complexity of the host rock and comparing the redistributed stress field with geological maps of the induced fractures the analyses show that if tectonic shears are not kinematically constrained mobilisation of the shears can play a key role in the development of the induced fracture network and therefore be a primary factor in the development of the excavation damaged zone this illustrates that under certain conditions rock mass heterogeneity in this case resulting from the tectonic shears may dominate over rock matrix anisotropy in this case resulting from bedding and must be considered when predicting the induced fracture network of the excavation damaged zone

an experimental study of the flow of gas along synthetic faults of varying orientation to the stress field implications for performance assessment of radioactive waste disposal critical stress theory states that fault transmissivity is strongly dependent upon orientation with respect to the stress tensor this paper describes an experimental study aimed at verifying critical stress theory using a bespoke angled shear rig designed to examine the relationship between gas flows along a kaolinite filled synthetic fault as a function of fault dip a total of 22 gas injection experiments were conducted on faults oriented 0 15 30 and 45 to horizontal both with and without active shear gas flow was seen to be complex repeat gas injection testing showed a consistent gas entry pressure but considerably different nonrepeatable gas peak or breakthrough pressure gas flow occurred along discrete dilatant pathways the physics governing the pressure at which these features formed was repeatable however permeability was dependent on the number distribution and geometry of the resultant pathways the nonrepeatable gas response suggests that the number of pathways was dependent on very subtle variations in gouge properties no fault orientations were seen to exhibit nonflow characteristics although critical stress theory predicted that two of the investigated fault angles should be effective seals however a small variation in gas entry pressure was seen with fault angle as a result of varying normal and shear stress acting on the gouge material shear was seen to enhance gas movement by reducing gas entry pressure and increased permeability once gas became mobile therefore in kaolinite gouge filled faults shear is not an effective self sealing mechanism to gas flow

seismic tomography of the excavation damaged zone of the gallery 04 in the mont terri rock laboratory summary an endoscopic antenna is used to perform a seismic cross hole tomography in the excavation damaged zone edz of the new g04 gallery of the mont terri underground rock laboratory switzerland excavated in opalinus clay more than 800 seismic traces were recorded between two vertical boreholes by combining 22 source and 48 receiver locations a vertical area of 1 2 3 4 m under the floor of the gallery is investigated with a high resolution tomography data with a very good quality allow to determine the traveltimes and the amplitudes of a 40 khz source wavelet propagating between the two boreholes the analysis of the traveltimes shows that the wave velocity is homogeneous but anisotropic with a minimum value of 2490 45 m s 1 in the direction normal to the bedding and a maximum of 3330 90 m s 1 parallel to the bedding the amplitude of the first arrivals strongly varies depending on the source receiver locations and suggesting an heterogeneous distribution of the attenuation coefficient of the seismic waves a bayesian inversion provides likely models of attenuation that are compared with geological observations the areas where fractures or cracks exist in the opalinus clay appear as highly absorbing the seismic waves

wave friction factor as related to the shields parameter for steady currents abstract the wave friction factor fw is an important dimensionless parameter used to estimate wave induced bed shear stress which together with current induced bed shear stress controls sediment transport in the marine and lacustrine environment however fw is either overestimated or underestimated by existing equations the matter is complicated by the fact that different equations must be used for hydrodynamically smooth or rough flows but the limit between these two boundary conditions is still poorly defined some equations also require estimated values for the nikuradse roughness length and the wave boundary layer thickness neither of which can be derived accurately it is therefore not surprising that fw values as calculated by existing equations differ by as much as a factor of 3 in the present paper fw is related to the shields parameter for unidirectional currents which not only facilitates the direct comparison and summation of bed shear stresses but also yields a more accurate equation valid for grains of different density in any fluid irrespective of the boundary condition

oxidation front and oxygen transfer in the fractured zone surrounding the meuse haute marne url drifts in the callovian oxfordian argillaceous rock

kimberlite emplacement temperatures from conodont geothermometry abstract kimberlites are mantle derived ultramafic rocks preserved in volcanic and sub volcanic edifices and are the main primary source of diamonds the temperatures of formation transport eruption and deposition remain poorly constrained despite their importance for understanding the petrological and thermodynamic properties of kimberlite magmas and styles of volcanic eruption here we present measured values of colour alteration indices cai for conodonts recovered from 76 paleozoic carbonate xenoliths found within 11 pipes from the chidliak kimberlite field on baffin island nunavut canada the dataset comprises the largest range of cai values 1 5 to 8 and the highest cai values reported to date for kimberlite hosted xenoliths thermal models for cooling of the chidliak kimberlite pipes and synchronous heating of conodont bearing xenoliths indicate time windows of 10 20 000 h and for these short time windows the measured cai values indicate heating of the xenoliths to temperatures of 225 to 925 c we equate these temperatures with the minimum temperatures of the conduit filling kimberlite deposit i e emplacement temperature t e the majority of the xenoliths record cai values of between 5 and 6 5 suggesting heating of xenoliths to temperatures of 460 c 735 c the highest cai values are consistent with being heated to 700 c 925 c and establish the minimum conditions for welding or formation of clastogenic kimberlite deposits lastly we use t e variations within and between individual pipes in conjunction with the geology of the conduit filling deposits to constrain the styles of explosive volcanic eruption

desaturation and structure relationships around drifts excavated in the well compacted tournemire s argillite aveyron france this study aimed to explore the relationships between the extension of rock desaturation and the excavation damaged zone edz subsequent to the excavation of a century old tunnel and of recent drifts 1996 and 2003 at the tournemire underground research laboratory url located in the aveyron county south of the massif central france the other objective of this work was to assess the impact of desaturation on the hydraulic head profile measured around the tunnel one section was selected per drift two boreholes were drilled for each section one parallel and one inclined 45 with respect to the bedding for each borehole we performed on site drill core mapping petrophysical measurements pneumatic and hydraulic tests by means of a modular mini packer system mmps results indicate that the edz around drifts is mainly a combination of unloading joints mimicking the drift shape and of desaturation cracks parallel to the bedding the edz extension around the tunnel is twice to three times that of the drifts of 1996 and 2003 and is essentially composed of unloading joints resulting from the mechanical response of the rock the masonery covering the tunnel walls is assumed to have protected the rock from seasonal variations of air humidity thus limiting without excluding the formation of desaturation cracks the edz extension deduced from core mapping is in agreement with that deduced from pneumatic tests with permeabilities several orders of magnitude greater than in the undisturbed zone degrees of saturation for the three sections range between 0 9 and 1 in the edz area and reach 1 in the undamaged zone the head profile deduced from measurements recorded since 2002 indicates the occurrence of an excavation disturbed zone edz of about 40 m around the tunnel this edz is likely due to the existence of sub atmospheric water pressures clearly seen in the first meter around the tunnel we have tried to quantify the impact of the tunnel since its excavation on saturation degree and on hydraulic heads the simulation was performed by considering as a first approach the absence of fracturing in the edz a constant suction of 3300 m deduced from the mean annual values of relative humidity and temperature measured in the tunnel atmosphere since 2002 was applied at the tunnel wall the degrees of saturation simulated around the tunnel are underestimated in the edz area and consistent to experimental data in the unfractured zone the modelling of hydraulic heads is overestimated in the horizontal direction and is in the domain of experimental values in the vertical direction but the lack of intermediate data cannot enable us to conclude on this consistency this study demonstrated the role played by fracturing on the distribution of petrophysical parameters and of heads around drifts and the century old tunnel it has also demonstrated the necessity of coupling mechanic and hydraulic calculations by considering capillary forces

gas injection test in the callovo oxfordian claystone data analysis and numerical modelling this paper describes a field scale experiment on gas transport mechanisms performed at andra s underground research laboratory url in a clay rock the experimental layout consists of two parallel boreholes that are equipped with multiple packer completions isolating three intervals each which have been continuously monitoring the pore pressure evolution of the clay rock nitrogen gas was injected in the middle test interval of one of the boreholes at increasing rates the entire gas test comprised six periods of controlled gas injections each followed by a shut in pressure recovery phase the experimental data are presented along with their interpretation by means of numerical modelling of two phase flow of gas and water using different numerical codes and different geometrical approaches that include axisymmetric half space and full 3d models an iterative modelling process was used to show step by step how an accurate description of each component of the experiment system produced a satisfactory reproduction of the experimental data and an improved understanding of the relevant phenomena for instance the initial volume of remaining water in the test interval and the presence of a damaged zone around the boreholes was important for the models to obtain good agreement with the field data

calculation of the conodont color alteration index cai for complex thermal histories abstract a simple model for the arrhenius reaction conodont color alteration index cai that can be implemented easily in a computer program is introduced the model named to as easycai envisages the overall process of conodont alteration as a series of 12 parallel pseudo first order reactions our approach is especially amenable to a spreadsheet program and can solve complex geological histories involving variable heating and cooling rates with easycai a profile of cai values versus time can be obtained for a given stratigraphic level if the time temperature history for that level has been estimated easycai can provide additional constraints to optimize thermal history models by computing profiles of cai values with depth and time thus providing a new tool for quantitative cai palaeothermometric analysis

analysis of flow path around the sealing section hg a experiment in the mont terri rock laboratory as part of the hg a experiment in the mont terri rock laboratory large scale in situ water gas injection experiments was conducted in a microtunnel this research work focuses on the numerical analysis of the experimental data and the in situ observations concerning a temporary change of the hydromechanical properties of opalinus clay during experimental operations three phases were numerically interpreted these included the generation of excavation damaged zone during tunnel excavation in which highly permeable flow paths around the tunnel have been formed the self sealing effect during water tests and the pressure evolution during a long term gas injection test a coupled two phase flow and mechanics model taking into account the strong anisotropic properties of opalinus clay was developed to interpret the measured data the hydraulic anisotropy was described by a transversely isotropic permeability tensor an elasto plastic model was established to consider both stiffness anisotropy and strength anisotropy anisotropic plasticity was studied using the microstructure tensor method

time dependent fracture formation around a borehole in a clay shale abstract opalinus clay a mesozoic clay shale has been chosen as host rock formation for the disposal of radioactive waste in switzerland for this study borehole damage zones were utilized as a proxy for an excavation damage zone that forms around a circular mechanically excavated tunnel in intact opalinus clay pilot boreholes were resin impregnated and over cored at different times after drilling to provide insight into the time dependent formation of fractures on both the micro and the macro scale observed fractures were characterized in terms of failure mode their relation to the rock anisotropy and the in situ stress tensor the analyses show that fractures that form in the short term initiate as shear fractures at the pilot borehole wall and propagate parallel to bedding typically a dominant shear fracture tangential to the pilot borehole wall was observed upon propagation of these shear fractures wing cracks horsetail splays and second order shears form sub parallel and sub perpendicular to bedding planes forming a complex fracture network which extends a quarter pilot borehole diameter into the rock mass in the longer term tangential shear fractures tend to propagate in a direction opposite to the initial propagation direction in addition new bedding parallel fractures deeper in the rock develop leading to the formation of thin slabs buckling of the slabs when unsupported and eventually progression of the buckling zone deeper into the rock mass buckling is associated with the formation of extensional fractures normal to bedding in the center and lateral to the buckling zone the zone of buckled rock slabs was found to have an extension of more than one borehole diameter at the time of preservation with resin in the short term the axis connecting the maximum failure depth on opposing sides of the borehole is parallel to the minimum stress direction in a plane normal to the borehole axis in the long term this axis rotates significantly towards the maximum stress direction primarily as a consequence of tangential shear fracture propagation slab formation and buckling dissipation of excess pore pressures may be the key process underpinning longer term fracture propagation and formation

characterizing the mechanical tensile behavior of beishan granite with different experimental methods abstract this work investigates with different test methods the mechanical tensile behavior of beishan granite especially the damage evolution process the granite is taken from the beishan site a potential chinese area for high level radioactive waste repository in the work three widely used tensile testing methods are employed namely the brazilian test with simplified isrm standard type i the brazilian test with the china standard type ii and the direct tensile test an acoustic emission test system is also used to capture the microcracking process under different loading conditions even though the tensile strength obtained by the three testing methods is similar some difference can still be noticed the highest value of average tensile strength 11 24 mpa is obtained by the indirect method proposed by irsm which is about 22 higher than the indirect method with china standard 9 15 mpa and about 18 higher than the direct tensile test 9 53 mpa the damage evolution process is further analyzed based on the recorded ae events it is revealed that in direct tensile testing the ae events accumulated mainly along the failure surface whereas in indirect tests the location and variation of ae events are much more complex moreover due to the stress concentration induced by the steel bars placed between the flat plate and the specimen the accumulation of ae events around the loading surface is more significant in the indirect test with the china standard than the accumulation recorded in the irsm method the recorded ae events give rise to a reasonable explanation of the macroscopic mechanical behavior of granite and are also valuable for understanding the damage evolution process of granite induced by tensile stress

microstructure and composition of brittle faults in claystones of the mont terri rock laboratory switzerland new data from petrographic studies geophysical borehole logging and permeability tests abstract claystones are considered as a geological barrier however the properties of claystone may be modified if these are cut by brittle faults and fractures investigations of fault rocks are therefore crucial to evaluate the barrier properties of clay rich formations the present study is dealing with the characterization of naturally and artificially deformed opalinus clay of the mont terri rock laboratory in nw switzerland complete core sections covering the artificially excavation damaged zone edz and several tectonic fault zones have been studied using a multidisciplinary approach consisting of geophysical geotechnical mineralogical geochemical and lithological structural data the fault zones encountered are characterized by a high density of planar discontinuities which often show slickenside striations under the microscope the fault zones turned out to be pervasively deformed resulting in open veins and pore space now filled with calcite and celestine fault zone reactivation led to very fine grained cohesionless fault gouge and fragmentation of the previously formed calcite veins packer tests in boreholes reveal excavation induced enhanced permeabilities up to 3 m borehole depth 1 9 m to gallery floor seismic borehole measurements indicate that seismic attributes which are typical for undisturbed opalinus clay are not reached until 7 5 m borehole depth 4 8 m to gallery floor which is larger than in the usual gallery configuration we interpret the anomalies in geophysical measurements as well as the elevated permeabilities measured in the main fault 3 6 m to 4 2 m to gallery floor to result from an enlarged edz influenced by the presence of the brittle fault structures the up to two orders of magnitude higher permeability compared to the intact claystone most probably results from excavation induced stress and a local reactivation of fault planes the results suggest that the presence of a fault zone can alter the extent of the edz significantly and thereby affect the rock integrity at least in the near field of a repository tunnel

measurement of in situ stress in weak rocks at mont terri rock laboratory switzerland in situ stress measurements in weak rocks such as clay shales that respond strongly to environmental changes are particularly difficult an extensive in situ stress measurement program has been conducted at the mont terri rock laboratory in northwestern switzerland hydraulic fracturing undercoring around a 600 mm diameter borehole using csiro triaxial strain cells and the borehole slotter were used to establish the state of stress for the opalinus clay at this location conflicting orientations and magnitudes resulted from the measurement programs three dimensional elastic modelling was used in conjunction with tunnel and borehole observations to establish the most likely stress tensor a stress measurement program using a borehole deformation gauge is currently underway to check the stress tensor resulting from the observational modelling

spatial predictions of geological rock mass properties based on in situ interpretations of multi dimensional seismic data abstract the article presents a statistical approach to characterize and predict engineering geological conditions in the up to 2000 m deep faido tunnel and gotthard base tunnel in switzerland seismic investigations were conducted to improve the technology of interpreting seismic tomographic images overall the goal of this study was to predict spacial maps of geological rock mass properties such as uniaxial compressive strength or total fracture spacing by using up to six seismic features in combination e g compression wave and shear wave velocities and dynamic poisson s ratio self organizing mapping som an artificial intelligent method was used for the purposes of interpreting multi dimensional geophysical attributes derived from seismic profiles of tomographic images along tunnel sidewalls the som method was applied in the faido tunnel to delineate complex physical relations between the geological and seismic parameters then the method was applied to predict geological properties around a segment of the gotthard base tunnel with unknown geological geotechnical conditions the results illuminate that correlation analyses pairwise parameter classification are substantially less powerful than the som method multi parameter classification in order to interpret geological features from seismic in situ data moreover predicted spatial distributions of the total fracture spacing and the uniaxial compressive strength for example corresponded well with drill core and tunnel mapping results the som approach was a helpful tool for practitioners in predicting zones of instabilities and geological complexity during underground excavation processes of the gotthard base tunnel it is suggested to use such an interpretation method as decision support for purposes of sub surface exploration and long term geophysical monitoring of large scale geoengineering projects such as disposals of nuclear waste and greenhouse gases or geopower plants for renewable energy geothermal biosoils

conodont geothermometry and tectonic overburden in the northernmost east greenland caledonides kronprins christian land lies at the northernmost limit of the east greenland caledonides and may be divided into four main tracts foreland parautochthon thin skinned thrust sheets containing neoproterozoic sediments and thick skinned thrust sheets of crystalline basement the eastern part of the foreland and the parautochthon are composed of ordovician silurian shelf carbonates overlain by llandovery lower wenlock turbidites deposited at the southern margin of the franklinian basin deformation of the parautochthon occurred beneath a major detachment the vandredalen thrust with neoproterozoic sediments of the rivieradal group lying in the hanging wall the rivieradal group was deposited in an e facing half graben and was displaced westwards across its rift shoulders during caledonian thrusting extensive sampling for conodonts has been carried out within the lower palaeozoic rocks of the foreland and parautochthon in order to increase the precision of structural interpretations and to provide data on maximum burial temperature and in turn the thickness of overburden in contrast to earlier studies conodont colour alteration indices cai show a gradual and continuous increase from cai 3 in the eastern part of the foreland to cai 5 in the easternmost parts of the parautochthon the isopleths are not disrupted or truncated by thrusting as previously suspected indicating that the heating is not attributable to pre thrusting stratigraphic overburden furthermore considerations of the regional geology indicate that there was no significant accumulation of sedimentary overburden in post caledonian time the predominant component is thus considered to be loading by thrust sheets modelling of the overburden thickness suggests that prior to erosion it increased from 3 9 km cai 3 in the easternmost foreland to a maximum of 12 5 km beneath the vandredalen thrust sheet in the easternmost part of the area providing constraints for restoring cross sections across the orogen

micro textural effects on crack initiation and crack propagation of andesitic rocks abstract the onset of dilation and uniaxial compressive strength ucs of rocks are known to be affected by mineralogical petrographic and microstructural features therefore micro textural variations are essential for understanding variation in strength and failure behaviour of rocks in this study volcanic rock samples with different micro textural characteristics from different locations in turkey were evaluated the mechanical tests revealed considerable variations in unconfined uniaxial compressive strength and the crack initiation ci threshold the ucs ranges between 108 289 mpa and ci ranges between 46 130 mpa detailed quantitative petrographic and mineralogical analyses were carried out on each tested specimen to understand these strength variations additionally microstructural studies were carried out on thin sections before and after mechanical perturbation to analyze 1 the effect of the main constituents of the rock specimens and mineral heterogeneity on crack initiation and propagation and 2 the orientation and distribution of micro and macro cracks formed during laterally unconfined compression the synthesis of mechanical mineralogical petrographic and microstructural data suggests that both the crack initiation threshold and peak strength are influenced by the ratio of the area of fine grain groundmass grains smaller than 200 m to amphibole and plagioclase phenocrysts in addition ci and ucs decrease with an increasing normalized area of biotite phenocryst

temporal behavior of a ventilated claystone at the tournemire url cross spectral analyses focused on daily harmonics abstract the main topic of this communication is the presentation of study auscultation and supervision procedures of deep geological radioactive waste storage repositories using natural harmonic forcings in this paper the effects of natural ventilation on the macroscopic behavior of a clayrock are investigated by means of time series recorded underground over a period of two years in the eastern part of gallery 1996 at the tournemire underground research laboratory url this study is based on time series acquired in the atmosphere at the gallery wall surface and inside the rock mass it includes measured signals from 6 thermo hygrometers 5 crack meters measuring the displacement of 2 shrinkage cracks and 3 tectonic fractures and a 1 meter fdr frequency domain reflectometry profile probe equipped with 6 sensors for measuring the volumetric pore water content into the rock mass auto spectral and cross spectral analyses using the concept of singular spectrum harmonics sshs and cross sshs are developed our analyses and interpretations focus here mainly on the solar diurnal atmospheric tide denoted s1 this tide corresponds to the insolation cycle of the earth atmosphere during a mean solar day 24 h 00 min this component is tracked throughout the various measured signals spectral tracking of tide fluctuations across signals this is equivalent in a way to analyzing the temporal behavior of the url during a mean solar day on earth results indicate that the daily natural forcing caused mainly by a combination of barometric and temperature related fluctuations is the most important effect overall on our various signals the daily harmonic induces the fluctuations of gallery air temperature relative and absolute air humidity and it leads to desaturation of the claystone which in turn leads to the claystone deformation and damage the effects of the annual harmonic sa may also be significant it was fully analyzed in the more complete version of this work however the sa results are not presented here because the spectral resolution on the annual harmonic is insufficient at this stage with only 2 years and 2 months of clean recorded data focusing the present study on daily fluctuations the cross spectral time shifts were obtained from the phase spectrum for the daily component s1 for various pairs of pore water content sensors located at different distances from the gallery wall these time shifts were then used to quantify a spectral velocity which is found to be on the same order than the hydraulic conductivities deduced previously from pneumatic tests performed in the excavation damaged zone of gallery 1996

mechanical analysis and interpretation of excavation damage zone formation around deep tunnels within massive rock masses using hybrid finite discrete element approach case of atomic energy of canada limited aecl underground research laboratory url test tunnel the construction of an underground opening leads to changes in the in situ stress regime surrounding the excavation the opening influences the rock mass owing to the redistribution of the stresses

recent advances in coalification studies and their application to geology abstract recent advances in coalification studies since 1970 are reported concerning microscopic methods causes of coalification the coalification process as such and application to geology the degree of coalification rank is mostly determined on the basis of vitrinite reflectance measured on finely dispersed material in rocks for rocks bare of vitrinite other microscopic methods are used such as fluorescence properties of liptinites and graptolite reflectance under incident light or coloration of microfossils like palynomorphs and conodonts in transmitted light the validity of the various methods is discussed maximum rock temperature and its duration are the main causes of chemical coalification reactions heating rates during subsidence influence the attainment of rank equilibrium contact metamorphic coals and natural cokes formed from bituminous coals are characterized by a relatively high reflectance and anisotropy strong frictional heat may cause local increase of rank adjacent to thrust planes graphitization is thermodynamically not possible in nature without pressure and shearing confining pressure retards the chemical coalification reactions tectonic stress especially shearing promotes the increase of maximum reflectance and of anisotropy it commonly leads to bi axial optical properties instead of the more typical uni axial negative geometry of vitrinite in undisturbed coal seams bi axial optical properties are common for vitrinite inclusions in clastic rocks on the basis of combined fluorescence microscopical and geochemical studies bituminization has been recognized as the characteristic part of coalification in the range between sub bituminous and bituminous coal it is characterized by the generation of petroleum like substances which enable the coal to soften and to agglomerate during carbonization hydrogenation properties are favoured by the bituminization process the different liptinite macerals behave differently during coalification and pass coalification jumps at different rank stages a considerable part of total inertinites is formed during early coalification brown coal to sub bituminous coal stage as rank inertinite this new knowledge appears to become important in relation to hydrocarbon exploration diagenetic methane some examples for the application of coalification studies to geology refer to vitrinite reflectance as an indicator of rock diagenesis and metamorphism palaeogeographical and structural history palaeogeothermics and hydrocarbon exploration large scale areal coalification studies in foredeeps and backdeeps of ancient and recent orogens suggest estimations of crustal thicknesses and relations to plate tectonics

polyphase metamorphism in the eastern carnic alps n italy s austria clay minerals and conodont colour alteration index evidence thermal evolution of the palaeozoic triassic sequences of the carnic alps has been characterized by b cell dimension and kubler index illite crystallinity of k white micas ki arkai index ai of chlorites clay mineral assemblages and conodont colour alteration index cai data indicate at least two metamorphic events variscan and alpine in the older event high anchizonal conditions predominated although epizonal conditions were reached over wide areas it was characterized by low intermediate pressure facies the thermal peak was mainly due to an extensional regime during the bashkirian a younger thermal overprint generated by alpine orogeny was of lower grade reaching high diagenetic anchizonal conditions characterized by high pressure facies inverted metamorphic patterns are associated with middle to late miocene thrusting hydrothermal alteration in the northern part of the region can be linked with emplacement of oligocene plutons and high heat flow along the periadratic lineament

ordovician metamorphic event in the carbonate platform of the argentine precordillera implications for the geotectonic evolution of the proto andean margin of gondwana an ordovician metamorphic event is recorded by means of conodont paleothermometry in the slope sedimentary sequences of the western precordillera allochthonous conodonts from reworked deposits of the eastern carbonate platform with cai 4 5 5 and autochthonous conodonts from the olistostrome matrix with cai 3 allow for constraining the metamorphic age within the paltodus deltifer and lenodus variabilis zones i e ca 480 465 ma the conodont data support an ordovician instead of an alternative devonian collision for the cuyania terrane with the proto andean margin of gondwana which is consistent with the earlier proposed but still contentious microcontinent model in the latter scenario the collision of the cuyania terrane caused unroofing and cannibalism of the leading edge of the carbonate succession and basement rocks the erosion of these rocks supplied detritus and metamorphosed conodonts to the deeper basinal settings of the western precordillera as the deformation front migrated into the peripheral foreland of the eastern and central precordillera nonmetamorphosed conodonts were eventually incorporated into the west prograding synorogenic clastic wedge the occurrence of allochthonous and autochthonous conodonts in the slope facies of the western precordillera provides a time constraint for the early accretion of the cuyania terrane and its transition to an evolving foreland mountain system in the ordovician period