hillslope drainage with sudden drawdown closed form solution and laboratory experiments theory is developed for hillslope drainage and is applied to the condition of sudden drawdown at the aquifer outlet the equations for prediction of cumulative outflow volume flow rate and water table profile are based on the boussinesq approximation for subsurface water flow above a sloping impermeable layer the advantages of the theory presented here are that the assumption of a long thin aquifer is unnecessary the same equations apply to both sloping and horizontal aquifers and the equations contain only parameters that are easily measured or estimated slope drainable porosity saturated hydraulic conductivity and layer thickness the accuracy of the outflow equations is illustrated by a series of laboratory experiments

isrm suggested methods for borehole geophysics in rock engineering in recent years many geophysical methods have been used in rock engineering for effective application of geophysics it is important to ensure that all aspects of a geophysical survey from the planning to the reporting are properly implemented to assist this in the field of rock engineering the suggested methods for geophysics have been drafted by the international society for rock mechanics commission on application of geophysics to rock engineering those for the land geophysics were already published in this journal last year this is the second volume of the suggested methods which describe borehole geophysics considering the present status of their utilization in rock engineering six types of geophysical methods used in boreholes velocity measurement along a borehole electric and electromagnetic logging nuclear logging vertical seismic profiling seismic tomography and resistivity tomography are described in addition since tunnels can be considered as boreholes seismic ahead of a tunnel face is also included in this volume because it has been often used in tunneling for each of the methods the following seven aspects of their deployment are described general applicability planning field operation data processing interpretation and output and report great emphasis is placed on aspects of planning and interpretation because they become more important in recent application of geophysics to rock engineering

modeling of rainfall triggered shallow landslide by integrating hydrological modeling with the infinite slope stability analysis a rainfall triggered shallow landslide model was developed by iverson water resour res 36 1897 1910 2000 in iverson s model the infiltration capacity is assumed to be equivalent to the saturated hydraulic conductivity for finding pressure heads analytically however for general infiltration process the infiltration capacity should vary with time during the period of rain and the infiltration rate is significantly related to the variable infiltration capacity to avoid the unrealistically high pressure heads iverson employed the beta line correction by specifying that the simulated pressure heads cannot exceed those given by the beta line in this study the suitability of constant infiltration capacity together with the beta line correction for hydrological modeling and landslide modeling of hillslope subjected to a rainfall is examined by amending the boundary condition at ground surface of hillslope in iverson s model the modified iverson s model with considering general infiltration process is developed to conduct this examination the results show that the unrealistically high pressure heads from iverson s model occur due to the overestimation of infiltration rate induced from the assumption that the infiltration capacity is identical to the saturated hydraulic conductivity considering with the general infiltration process the modified iverson s model gives acceptable results in addition even though the beta line correction is applied the iverson s model still produces greater simulated pressure heads and overestimates soil failure potential as compared with the modified iverson s model therefore for assessing rainfall triggered shallow landslide the use of constant infiltration capacity together with the beta line correction needs to be replaced by the consideration of general infiltration process

observation and analysis of near surface pore pressure measurements in clay shales slopes clay shales largely outcrop in the northern apennines of italy where they are associated with frequent and widespread landslide activity the paper presents the results of monitoring activities carried out in two field sites and focused on the hydrology of clay shales prone to landsliding in the monitored slopes the water table is close to the ground surface throughout the year with seasonal fluctuations of tens of centimetres to a couple of metres shallow weathered soils or clay cover and unaltered material exhibit a much different behaviour although responses to single rainfalls are clearly identifiable as pressure pulses in the clay cover they are never observed in the underlying parental clay shales where downward gradients indicate recharge and only long term seasonal fluctuations are recorded short term variations of pressure head in the clay cover are ruled by downward propagation of a pressure wave in saturated conditions more than 400 pore pressure responses collected in the two sites are analysed in terms of lag time rate and amount of pressure increase and timing of pressure peaking it emerges that the linear diffusion theory can satisfactorily explain the observed behaviour in deeper unaltered material the barometric effect influences the measures similarly to what is observed in confined aquifers after its removal the corrected data exhibit regular seasonal fluctuations which are used to estimate the diffusivity of the material based on phase lag and attenuation of the downward propagating long term periodic pulse copyright 2011 john wiley sons ltd

comparison of geoelectrical imaging and tunnel documentation at the hallandsas tunnel sweden article i nfo for construction in rock a thorough pre investigation is important in order to avoid unforeseen conditions which may delay the work it is crucial to remember the results from this investigation in the further work and use the experience from the construction to update the geological prognosis and reduce the uncertainties different geophysical methods have proved valuable tools in such investigations in this work the electrical imaging is evaluated with regards to the method s applicability the evaluation is done qualitatively by comparing the electrical imaging with tunnel documentation from a tunnel in southern sweden by evaluating the result continuously when making the tunnel a more detailed geological prognosis can be compiled and used in the continued work with the tunnel the parameters used for the comparison are lithology q rqd weathering and water leakage the result was that virtually every change in electrical resistivity image coincides with a change in rock conditions the general trend was that high resistivity corresponded with good quality gneiss whereas low resistivity corresponds to poor quality rock e g high weathering low rqd low q and or several lithological contacts the intermediate resistivity is often amphibolites or rock with water bearing fractures the results were supported by in situ resistivity measurements inside the tunnel and resistivity logging in a core drilling geoelectrical imaging proved to give valuable information for a detailed geological model which could be compiled for a section where the tunnel had not yet been drilled as a help for planning of the continued tunnel work as is the case other geophysical methods it is clear that for the interpretation of data a priori information about the geological setting is necessary

electrical resistivity tomography applied to groundwater aquifer at downstream of chih ben creek basin taiwan groundwater resource investigations primarily involve inferring groundwater levels and recharge sources from factors such as the distributed location and range subsurface geological structure and flow paths of groundwater sources this study conducted an investigation on the underground aquifer at the downstream of the chih ben creek basin taiwan in addition convenient rapid and accurate two dimensional electrical resistivity tomography ert was employed for evaluations the cross sectional ert image indicates that the low resistivity region in the stratum at survey line cb01 may be a groundwater deposit or fracture zone this region can be divided into three major segments the segment that is 0 50 m from the survey line exhibits a decreasing trend and is thus inferred to be a recharge source survey line cb02 can be generally divided into four layers with the second layer containing a greater amount of groundwater this layer is an aquifer with a depth of approximately 25 100 m below the ground surface and 75 100 m in thickness the base of the aquifer slopes toward the east and primarily possesses a lithological composition of slate and sandstone with explicit and fractured joints

allanite and other ree rich epidote group minerals epidote group minerals rich in rare earth elements ree in particular allanite are common accessory phases in igneous metamorphic metasomatic and sedimentary rocks small amounts of ree are present in most epidote group minerals but in allanite and the related minerals dissakisite ferriallanite dollaseite khristovite and androsite the ree are essential structural constituents an important characteristic of ree rich epidote group minerals is that their octahedrally coordinated m sites contain major amounts of divalent cations this paper summarizes literature data for these minerals and discusses their chemistry occurrence phase relations and petrologic and geologic significance the chapter emphasizes allanite because it is the most common and best studied of the ree rich epidote group minerals epidote group minerals contain isolated silicon tetrahedra and corner sharing groups of two tetrahedra and are thus assigned to the disilicate or sorosilicate structural family for a detailed description of the structure see franz and liebscher 2004 the epidote group structural formula is a2m3 sio4 si2o7 o f oh or in a simplified form a2m3si3o11 o f oh in which a ca sr pb2 mn2 th ree3 and u and m al fe3 fe2 mn3 mn2 mg cr3 and v3 deer et al 1986 there are two structurally different a sites a 1 and a 2 with different coordination numbers and there are three different m sites m 1 m 2 and m 3 which are all octahedrally coordinated ueda 1955 dollase 1971 in epidote group minerals trivalent ree are accommodated in the a sites which in endmember epidote both contain ca the incorporation of ree3 is commonly charge balanced by a divalent cation fe2 mn2 mg substituted for a trivalent one in the m sites table 1

reply to comments on drainage from a uniform soil layer on a hillslope by f stagnitti m b parlange t s steenhuis and j y parlange

detection and correlation of tephra derived smectite rich shear zones by analyzing glass melt inclusions in mineral grains abstract shear zones rich in the clay mineral smectite are significant geological features because of the particular physicochemical properties of this mineral however predicting the distribution of such shear zones using limited borehole data is a challenge for geoscientists and geoengineers here we present detailed mineralogical and geochemical analyses of clay rich shear zones 30 cm thick that are associated with bedding parallel or bedding oblique faults in drill cores of a siliceous mudstone containing mainly opal cristobalite tridymite from the horonobe area northern hokkaido japan the bedding parallel shear zones are rich in smectite and some shear zones are characterized by melt inclusions hosted by plagioclase and quartz the chemical compositions of melt inclusions in six shear zones are very similar but distinct from those of melt inclusions in other shear zones these six shear zones consistently occur in horizons 350 m shallower than a known tephra layer these mineralogical characteristics and stratigraphic positions suggest that the six shear zones occur within the same tephra layer and that the smectite formed as a result of burial diagenesis of volcanic glass tephra derived smectite rich shear zones can be detected and correlated by analyzing melt inclusions preserved in mineral grains the distribution of such shear zones can be predicted in a similar way to tephra layers

mathematical simulation of interdependent surface and subsurface hydrologic processes it has become popular with some hydrologists to consider runoff produced by rainfall intensities in excess of soil infiltration capacity horton excess and runoff produced by rain falling on saturated soil zones saturation excess to be alternative or competitive models for describing surface runoff on the contrary we contend with freeze 1972 that these two mechanisms along with subsurface stormflow are three parts of a continuum of hydrologic response that are controlled by the relative properties of the soil and the rainfall we introduce a model which trades some of the generality of the freeze 1972 hillslope model for increased efficiency by selecting efficient approximations for key elements in hillslope hydrodynamics infiltration and movement in the unsaturated flow zone the hillslope is considered to consist of two soil layers with the lower soil capable of restricting vertical flow at the interface to create a perched aquifer and subsurface stormflow the slope of the interface is arbitrary a kinematic method for routing unsaturated vertical flow is described and is linked consistently with a modern analytically derived infiltration model which operates when rainfall exceeds surface saturated hydraulic conductivity ks the model is used to demonstrate several of the relationships between rainfall flux soil hydraulic properties hillslope geometry and runoff characteristics the model is also applied to simulate experimental data from a hillslope in western australia subsurface stormflow recessions are demonstrated to be affected by the ratio ks ql anisotropy and spatial distribution of saturated hydraulic conductivity ks where ql is the rate of loss from the perched aquifer vertical growth of the saturated zone depth is demonstrated to have a potentially greater effect on runoff than horizontal movement in cases where anisotropy and or slope is not severe

observation and analysis of pore pressure fluctuations in a thin colluvium landslide complex near cincinnati ohio abstract field observations in a thin colluvium landslide complex along the ohio river near cincinnati show that measurable late winter and spring pore water pressure increases occur when several centimetres of rain fall over a period of one or more days average pre storm fillable porosity of 9 suggests that the colluvium was near saturation during the period of record dimensional analysis of flow through a sloping homogeneous layer of uniform thickness shows that short term pore pressure fluctuations in very nearly saturated soils can be approximated by a one dimensional linear diffusion equation the concept of slope parallel and slope normal characteristic times is also introduced to determine the conditions under which slope parallel and slope normal flow will predominate analytical solutions to the diffusion equation are then used to investigate the effects of storm frequency and magnitude on pore pressure fluctuations comparison of solutions for layers of finite and infinite thickness shows that an impermeable substrate nearly doubles pore pressures along the substrate for storms of short duration however the effect of an impervious boundary vanishes with increasing duration finally measured rainfall values are incorporated into a finite difference simulation of the observed pore pressures with good results

the effect of sample disturbance on laboratory properties of lac du bonnet granite laboratory properties of lac du bonnet granite samples collected at depths ranging from near surface to 1000 m were established the laboratory properties indicated that either the in situ properties were changing with depth or the samples were changing with depth comparison of p wave velocities in the samples and in situ confirmed the latter i e sample disturbance was affecting the laboratory properties the strength of the damaged samples indicated that sample disturbance affected the cohesion of the material not the frictional properties and that the cohesion loss cannot be accounted for by applying a confining stress sample disturbance started to affect the laboratory properties of lac du bonnet granite when the maximum far field in situ stress exceeded about 10 of the unconfined compression strength key words sample disturbance core discing cohesion brittle rocks damage microcracks stress dependent young s modulus

comments on drainage from a uniform soil layer on a hillslope by f stagnitti m b parlange t s steenhuis and j y parlange note 23 1704 reference eflum article 1987 001 record created on 2005 09 08 modified on 2017 02 23

a diagenesis model for geomechanical simulations formulation and implications for pore pressure and development of geological structures forward basin modelling is routinely used in many geological applications with the critical limitation that chemical diagenetic reactions are often neglected or poorly represented here a new temperature dependent kinetic diagenesis model is formulated and implemented within a hydromechanical framework the model simulates the macroscopic effects of diagenesis on 1 porosity loss 2 sediment strength 3 sediment stiffness and compressibility 4 change in elastic properties 5 increase in tensile strength due to cementation and 6 overpressure generation a brief overview of the main diagenetic reactions relevant to basin modelling is presented and the model calibration procedure is demonstrated using published data for the kimmeridge clay formation the calibrated model is used to show the implications of diagenesis on prediction of overpressure development and structural deformation the incorporation of diagenesis in a uniaxial burial model results in an increase in overpressure of up to 9 mpa due to both stress independent porosity loss and overpressure generated by disequilibrium compaction caused by a reduction in permeability finally a compressional model is used to show that the incorporation of diagenesis within geomechanical models allows the transition from ductile to brittle behaviour to be captured due to the increase in strength that results in an over consolidated stress state this is illustrated by comparison of the present day structures predicted by a geomechanical only model where a ductile fold forms and a geomechanical model accounting for diagenesis in which a brittle thrust structure is predicted

estimation of the highest potential transmissivity of discrete shear fractures using the ductility index abstract previous studies indicated that the highest potential transmissivities of fractures in fault zones might be well estimated by a mechanical indicator the ductility index di the di is defined as the effective mean stress normalized to the tensile strength of the intact rock mass the mechanism of formation and preservation of pore structures in fault zone fractures can be explained by local shear induced tensile stresses and pore structures in discrete shear fractures may form in the same way i investigated therefore whether the di model can correctly predict the highest transmissivities of shear fractures recorded in fractured neogene diatomaceous mudstone koetoi formation where fault zones and joints are rare but discrete shear fractures without mineral fillings are abundant analyses of the shear fractures reveal that the detected states of paleostress are nearly equal to the current stress state implying the shear fractures have potentially been tectonically active thus the highest transmissivities detected at fractures by flowing fluids electric conductivity ffec borehole logging may potentially be treated as the highest potential transmissivities in terms of the given dis relationships between the transmissivities of flow anomalies and dis fit the existing di model well which suggests the model is applicable to discrete shear fracture systems as well as fault zones

seventeenth canadian geotechnical colloquium the effect of cohesion loss and stress path on brittle rock strength stress strain curves for brittle rocks show three characteristic stress levels crack initiation long term strength and peak strength damage controlled testing at low confining stresses has shown that the long term and peak strengths are sensitive to the amount of induced damage i e the greater the amount of damage the lower the long term and peak strengths these tests also showed that the brittle failure process is characterized by a loss of cohesion as friction is mobilized excavation of a circular test tunnel in massive brittle rock resulted in failure around the tunnel the back calculated strength for the failed rock around the tunnel is approximately one half of that measured in laboratory tests crack induced damage of lac du bonnet granite both in the laboratory and in situ begins when the load exceeds approximately one third of the unconfined compressive strength however the stress level associated with failure is a function of loading path in the laboratory where the loading path monotonically increases the ultimate strength of an unconfined sample is 225 mpa numerical studies suggest that in situ the loading path around the tunnel is more complex involving stress increase and decrease and stress rotation for this loading path failure initiates at a stress between 100 and 120 mpa conventional frictional failure criteria did not adequately predict the extent of brittle failure measured around the circular tunnel the results from the damage controlled laboratory tests and the microseismic monitoring carried out during tunnel construction indicate a constant deviatoric stress criterion is a reliable indicator for predicting the onset of damage this criterion was also found to give a reasonable prediction for the maximum depth of failure around the test tunnel the fundamental assumption in the constant deviatoric stress criterion is that at low confining stresses such as those which occur around underground openings the brittle failure process is dominated by cohesion loss

silica diagenesis of neogene diatomaceous and volcaniclastic sediments in northern japan marine diatomaceous siliceous sediments in neogene sections of northern japan contrast with the monterey shale of california in containing many intercalations of acidic volcaniclastic sediments diagenesis of these sediments from deep boreholes and surface sections was investigated three diagenetic zones biogenic opal opal ct and quartz zones are recognized in siliceous sediments corresponding roughly to amorphous silica low cristobalite and quartz zones in acidic vitric volcaniclastic sediments opal ct consists almost exclusively of silica and water while low cristobalite contains appreciable amounts of a1 ca na and k in subsurface sections values of d 101 spacing of opal ct decrease progressively with increasing burial depth the progressive ordering is not associated with additional silica cementation in surface sections the behaviour of d 101 spacing is complicated owing to the modification of the progressive ordering developed during burial diagenesis by later silica cementation during uplift the cementing opal ct is probably precipitated from percolating groundwater which dissolves siliceous skeletons in porous diatomaceous mudstones overlying the opal ct porcellanite opaline cherts that form during burial diagenesis are designated as early opaline chert while those which form during uplift are later opaline chert the later opaline chert contains two groups of opal ct one is progressively ordered opal ct and the other is additionally cemented opal ct with higher d 101 spacing than that in the host porcellanite in diatomaceous siliceous sediments early opaline chert is scarce most if not all opaline cherts in surface sections are of later origin

application of seismic tomography for detecting potential seepage paths in bakhtyari dam iran abstract bakhtyari dam and hydropower plant project is one of the largest hydroelectric projects in iran this dam is located in lorestan in southern iran on the bakhtyari river which is a headstream of the dez river previous gallery surveying showed that some open joints were present in the abutments these joints may act as a good conduit for seepage five galleries were used to carry out seismic tomography in the right and left abutments gr1 gr2 and gr3 gl2 gl3 totally 765 m the objective of the tomography was to detect these weak zones susceptible for seepage velocity images obtained by p wave travel time tomography indicated that in the level of gr2 gallery upward there is a large zone of low velocity but the rock mass quality seems better in the left abutment in spite of unfavorable condition in r 23 block gr2 gr3 the p wave velocity between gr2 and gr1 galleries is in the range of undisturbed limestone despite the presence of these weak zones the placement of the dam is where the rock mass quality is good and the design of the grout curtain could help to bypass the reservoir water away from these seepage paths

induced liquefaction experiment in relatively dense clay rich sand deposits 1 in this paper we report results from a controlled blast induced liquefaction experiment at the field scale the physical and mechanical properties of the materials at the subsurface are characterized by a suite of in situ and laboratory tests including the standard penetration test spt downhole and cross hole seismic velocity tests density porosity and gradation tests and direct shear tests since the blast experiment was performed above groundwater table the subsurface was saturated by a sequence of controlled infiltration tests a 50 kg tnt charge was detonated at a depth of 10 m and seismic ground motions were recorded in a vertical geophone array positioned at a horizontal distance of 30 m from the blast borehole obtained liquefaction features include a water fountain that erupted from the blast borehole prolonged bubbling of the water surface inside the infiltration trench a process equivalent to sand boils typically observed at sites which have experienced liquefaction lateral spreading and surface settlement we argue that in contrast to conventional predictions liquefaction may be induced in relatively dense silty and clayey sands shear wave velocity 300 m s 1 relative density 63 89 relatively rich in clays fines content 30 and that the driving mechanism should not necessarily be restricted to cyclic shear stress loading

effects of degree of saturation on shallow landslides triggered by rainfall the empirical rainfall threshold concept and the physical based model are two commonly used approaches for the assessment of shallow landslides triggered by rainfall to investigate in detail the rainfall triggered shallow landslides many physical based models coupling the infinite slope stability analysis with the rainfall infiltration modeling in variably saturated soil were developed however in those physical based shallow landslide models the unit weight and the unsaturated shear strength were assumed constant rather than depending on the degree of saturation in this study the effects of the unit weight and the unsaturated shear strength as function of degree of saturation on rainfall triggered shallow landslides are examined several designed scenarios and a real case scenario are used to conduct the examinations the results show that not only the occurrence of shallow landslides but also the failure depth and the time to failure could be misassessed if the influences of degree of saturation on the unit weight and the unsaturated shear strength are neglected

quartz types authigenic and detrital in the upper cretaceous eagle ford formation south texas usa abstract lithologic heterogeneity of the eagle ford formation in south texas arises from mixing of extrabasinal grains of siliciclastic composition with intrabasinal grain assemblages composed dominantly of marine carbonate with a lesser component of biosiliceous debris detrital quartz in particular is derived from both extrabasinal and intrabasinal sources posing a challenge for the use of bulk compositional data for mudrock classification extrabasinal detrital quartz supplied along a major axis of siliciclastic influx the woodbine depositional system of east texas is reduced to a minor part of the grain assemblage in south texas petrographic evidence and point count results indicate that around 85 percent of total quartz in these rocks equal to about 12 6 volume percent is authigenic thus significant quantities of authigenic silica are not restricted to siliceous mudrocks but can be found in carbonate rich mudrocks as well formerly opaline skeletons of radiolaria the dominant source of silica for authigenic quartz precipitation are only poorly preserved by replacements including calcite dolomite pyrite and quartz dissolved silica released by dissolution of radiolarians and perhaps also by volcanic glass dissolution is re precipitated in a variety of forms including matrix dispersed microquartz cement fillings within primary intragranular pores and grain replacement of both calcareous and siliceous allochems the mass balance of dissolved silica mobilized from radiolarians and other reactive silicates and the precipitation of authigenic quartz is uncertain because the initial volumes of now dissolved detrital material versus the final volume of authigenic material quartz and other authigenic silicates cannot be determined with accuracy

khmer sandstone quarries of kulen mountain and koh ker a petrographic and geochemical study abstract sandstone from several ancient quarries and natural outcrops located at the eastern foothill of kulen mountain and in koh ker northern cambodia has been characterized by means of petrographic analysis scanning electron microscopy and geochemical analysis the samples have been collected during a series of field surveys organized jointly by the metropolitan museum of art and the authority for the protection and management of angkor and the region of siem reap apsara the data show how the sandstone quarried from these sites is characterized by an overall petrographic and geochemical homogeneity and is consistent with the upper terms of the lower middle jurassic terrain rouge formation this result suggests that petrography and geochemistry of sandstone belonging to the terrain rouge formation might not be unambiguously characteristic of single quarry sites but rather representative of vast portions of the sedimentary sequence

modeling of layered infinite slope failure triggered by rainfall the infinite slope is typically regarded as composed of a single layered soil with a uniform property in various physical based models used for modeling rainfall induced shallow landslides this study extends the physical based model to consider the layered infinite slope to examine the importance of soil layer distribution for rainfall induced shallow landslides hypothetical scenarios of infinite slope composed of soil layers with different thicknesses and parameters are employed to conduct this examination the results show that pressure heads caused by rainfall infiltration are strongly related to soil layer distribution this shows the significant influence of soil layer distribution in assessing infinite slope stability failure of a layered infinite slope does not necessarily occur at the impervious bottom of the hillslope soil but may also occur at the interface between two soil layers this result shows that a neglect of soil layer distribution could misestimate failure depth hence soil layer distribution must be considered to reliably analyze infinite slope failure induced by rainfall

consideration on the construction process and the sandstone quarries during the angkor period based on the magnetic susceptibility abstract detailed magnetic susceptibility measurement was conducted on the sandstones used for the angkor monuments constructed in the period spanning the preah ko and angkor wat styles and the construction process of the buildings and quarries of the sandstones was considered combined with the previous study on the sandstones of the bayon style uchida e cunin o shimoda i suda c nakagawa t 2003 the construction process of the angkor monuments elucidated by the magnetic susceptibility of sandstone archaeometry 45 221 232 the magnetic susceptibility measurement revealed that there were 7 sandstone quarries corresponding to stages i ii iii iva v vii and viiib during the angkor period the sandstones used for the monuments belonging to stage i show average magnetic susceptibility values ranging from 1 1 to 2 3 10 3 si units in the bakheng style period stage ii the average magnetic susceptibility of the supplied sandstones decreased gradually from around 10 to 1 10 3 si units over time the magnetic susceptibility range of the sandstones used for the monuments of stage iii was from 2 3 to 3 0 10 3 si units in the early angkor wat style period ivb the average magnetic susceptibility of the supplied sandstones increased over time reflecting the supply of the sandstones from two different quarries that is the quarry corresponding to the khleang and baphuon style monuments stage iva with low average magnetic susceptibilities of 1 1 to 2 4 10 3 si units and the quarry corresponding to the main angkor wat style monuments stage v with high average magnetic susceptibilities ranging from 2 8 to more than 4 3 10 3 si units the sandstones of stage vii show low average magnetic susceptibility around 1 10 3 si unit the sandstones of stage vid is a mixture of sandstones of stages v and those of stage vii the sandstones with high magnetic susceptibilities are found in the monuments belonging to stage viiib reflecting the supply from the new sandstone quarry

nature and provenance of the sandstone used for bayon style sculptures produced during the reign of jayavarman vii under jayavarman vii 1182 83 ca 1218 ce the khmer empire reached its apex leaving a heritage of major construction works and unique artistic production the stone materials of several sculptures produced under his reign were characterized and compared to possible geological sources in northern and eastern cambodia the data suggest that a specific type of sandstone rich in volcanic detritus was deliberately selected and quarried from a triassic sedimentary sequence exposed far from angkor the main political and economic center at that time

topkapi a model for the representation of the rainfall runoff process at different scales the paper introduces a new distributed rainfall runoff model derived upon the assumption that the horizontal flow at a point in the soil and over the surface can be approximated by means of a kinematic wave model the point assumption is then integrated up to a finite pixel dimension thus converting the original differential equation into a non linear reservoir equation based upon physically meaningful parameters the solution of which can be found numerically the catchment behaviour is finally obtained by aggregating the non linear reservoirs into three cascades representing the soil the surface and the drainage network following the topographic and geomorphologic elements of the catchment the main advantage of this approach lies in its capability of being applied at increasing spatial scales without losing the physical interpretation of the model and parameters other advantages of the topkapi approach can be found in the full use of the digital elevation model soil maps land use maps etc for the derivation of the non linear reservoir cascade and for the estimate of the model parameters this allows for the extension of the model to ungauged catchments and as a promising tool for the impact assessment of climatic as well as land use changes three case studies are presented showing the model application to catchments that are different in nature and size from a few to over a thousand square kilometres and described by means of widely different elementary grid cells pixels the results of these applications are interesting and they essentially fulfil the general purpose although the work to be done is still great the model appears to be a promising tool worthy of further investigation

reservoir rock properties of coal measure strata of the lower monongahela group greene county southwestern pennsylvania from methane control and production perspectives abstract the methane emission rate into an underground mine environment from overburden strata during longwall mining is impacted by reservoir and geomechanical characteristics of the coal measure rocks in the overlying strata as well as the presence of any coal seam the reservoir characteristics and how they change during mining potentially affect the performance of gob gas ventholes which consequently impacts the efficiency of methane control in the mining environment this study presents reservoir and elastic properties of coal measure rocks in the lower monongahela group in greene county southwestern pennsylvania of the northern appalachian basin since the source of methane in this region from underground mining is located between the sewickley coal and the pittsburgh coal a specific emphasis was given to this interval core analyses were performed in the laboratory to determine rock porosity and permeability geophysical logging data gamma density sonic obtained from two exploration boreholes were used for evaluating formation boundaries shale contents log porosities and geomechanical properties of formations permeability was also calculated using density log data and empirical equations and compared with laboratory measurements and slug tests performed in isolated intervals of boreholes the results presented in this study can be used as data sources for reservoir studies related to the production and control of methane

in situ experiments on an excavation disturbed zone induced by mechanical excavation in neogene sedimentary rock at tono mine central japan abstract the excavation disturbed zone edz is defined as the rock zone where rock properties and conditions have been changed due to the processes induced by excavation such as fracturing stress redistribution and desaturation based on our results of the in situ blasting excavation disturbance experiment at the tono mines the rock mass around the drift behaved elastically and the excavation damage induced by blasting was considered to be a primary factor in causing a change in rock properties the excavation damage was considered to depend on the excavation method so we performed an excavation disturbance experiment with mechanical excavation using a boom header in the neogene sedimentary soft rock to compare the rock property change and width of the edz induced by blasting geological observation rock mass displacement and vibration measurement were performed during the drift excavation seismic refraction and tomographic surveys borehole expansion test and hydraulic test were performed before and after the drift excavation a low seismic velocity layer of the edz with a width of ca 0 3 m and a seismic velocity of 65 70 of the intact rock was detected by a seismic refraction survey along the drift wall deformability and hydraulic conductivity were not changed in the rock mass up to 0 3 m from the drift wall the change in rock properties and width of the edz was shown to depend on the excavation method in this geological setting the mechanical excavation method is more effective in limiting the extent of the edz and change in rock mass properties

opal a opal ct phase boundary inferred from bottom simulating reflectors in the southern south korea plateau east sea sea of japan 1 multi channel seismic reflection profiles from the trough areas of the southern south korea plateau east sea sea of japan reveal high amplitude positive polarity bottom simulating reflectors bsrs at about 500 ms two way travel time ca 450 m below the seafloor the positive polarity and no noticeable drop of frequency low frequency shadow below the bsr strongly suggest that the bsr is due to an opal a opal ct phase boundary the bsr often marks a sharp interface between low amplitude reflections above and high amplitude reflections below the weak but distinct reverse polarity event seen 70 150 ms two way travel time below the bsr may represent the base of the silica diagenetic zone the geothermal gradients 78 111 c km estimated from the sub bottom depth of the bsr are comparable to that 98 c km measured at the nearby kita yamato trough where the opal a opal ct boundary has been penetrated by the ocean drilling program odp drilling

on subsurface stormflow predictions with simple kinematic theory for saturated and unsaturated flows this paper provides analytical solutions for some simple cases of subsurface stormflow the solutions are based on kinematic approximations in both unsaturated and saturated zones solutions for rising falling and partial equilibrium hydrographs are given the analytical model has been applied to data collected on a hillslope of the east twin brook catchment mendip united kingdom measured and predicted hillslope hydrographs were in good agreement

mine by experiment in a deep shaft in neogene sedimentary rocks at horonobe japan abstract the japan atomic energy agency jaea has been implementing several research studies at the horonobe underground research laboratory url in support of the japanese r d program for the geological disposal of high level radioactive waste hlw understanding the development and properties of an edz excavation disturbed or damaged zone including the rock mechanical hydrogeological and geochemical responses around excavated openings is important to the design of plugs and sealing material and for performance assessment of geological disposal the mine by experiment described in this paper was carried out to investigate the development of an edz in one of the deep vertical shafts excavated in neogene sedimentary rocks at the horonobe url site the objective of this study is to obtain fundamental parameters of an edz in neogene sedimentary rock where case studies are few in support of the geological disposal studies in japan before and after shaft sinking btv borehole television borehole expansion tests permeability tests and seismic velocity logging were carried out to determine initial conditions and changes in the mechanical and hydraulic properties during shaft sinking extensometers were installed in the rock mass to determine rock mass response to excavation the variation of hydraulic properties was largest within one meter of the shaft wall and the variation in hydraulic conductivity was in the range of one order of magnitude

an improved approach for evaluating the time dependent stability of colluvial landslides during intense rainfall the paper presents an improved analytical approach for evaluating the time dependent stability of colluvial landslides during intense rainfall infiltration the approach comprises two steps first to simulate rainfall infiltration and then to compute the safety factor in terms of the irregularity of the natural landslide surface in implementation of the method the landslide is divided into several soil slices with approximately straight sides each single slice is regarded as a finite slope so that the infiltration formula and safety factor can be deduced the infiltration formula is derived with combination of the green ampt model and mass conservation law considering seepage perpendicular and parallel to slope surface simultaneously in the modified infiltration model both size effect and angle effect are vividly observed in the process of rainfall infiltration into the finite slope while the former of which is not presented in the original green ampt model the safety factor is computed using the limit equilibrium method with the influence of infiltrating water on the shear strength gravity and seepage force of soil slices considered by case study of the shuping landslide in three gorges decline in the safety factor and the decrease in the tendency are definite specifically under the rainfall intensity of 50 mm h the failure of shuping landslide is most likely to occur at the time of 102 h in addition the results highlight shallow failure along the wetting front under intense rainfall

damage phenomenon and petrophysical properties of sandstones at the phnom bakheng temple angkor cambodia first investigations and possible conservation measures sandstones clay in the form of bricks and laterite are the building materials used by the khmer to construct the imposing and magnificent temples in southeast asia many of these monuments suffer from fracturing sanding contour scaling crust formation and salt weathering the affinity to weathering is closely connected to the type of material two sandstone types classified as feldspathic arenite and quartz arenite of angkor as well as two arkosic sandstones from thailand are described and investigated in this study important petrophysical properties determined for the different sandstones consist of hydric expansion thermal expansion pore radii distribution and ultrasonic velocity different investigations such as capillary water uptake surface hardness hygroscopic water sorption and salt resistance tests were undertaken in the laboratory to characterize the various rock types observations and quantified damage mapping were done onsite at the phnom bakheng temple contour scaling in the form of weathering crusts is one of the main deterioration features observable at the angkor monuments comparisons are made between the building stone the crust material from the phnom bakheng temple and fresh stone material used for restoration significant differences in hydric and especially in thermal expansion of the crust and sandstone have been determined the results seem to indicate that extensional processes occur which can be considered a force for detachment i e contour scaling flaking in an experimental trial the hydric and thermal expansion of the weathering crust and the building stone was significantly reduced by using a weak acid for the crust and a swelling inhibitor for the original building stone

fluid flow due to the advance of basin scale silica reaction zones the conversion of biogenic silica opal a to opal ct cristobalite and tridymite in biosiliceous sediment causes increased rates of water expulsion because of the reduction in sediment porosity and dehydration of the amorphous opal a phase this release of water occurs over large tracts of sedimentary basins during sediment burial within discrete diagenetic reaction zones analysis of two dimensional and three dimensional seismic data sets from basins in the northern hemisphere provides geophysical evidence for a variety of fluid conduits and roughly circular erosional depressions at the contemporaneous seabed we interpret these features as indicative of water expulsion and focused fluid flow emanating from opal a to opal ct reaction zones at burial depths within the range 200 800 m the rate at which water is expelled depends upon the degree of porosity reduction and the weight fraction of bound water at the reaction zone as well as the rate of advance of the reaction zone where the reaction is actively taking place within homogeneous biosiliceous sediment the rate of water expulsion is independent of the reaction rate this is because water is released across the entire reaction zone therefore slow reaction rates are compensated for by expulsion of water across wider reaction zones we calculate the rate and volume of water expulsion for the faeroe shetland basin where the sediment immediately below the reaction zone contains on average 30 opal ct by weight the estimated volumetric rate of water expulsion per unit surface area at the present day is 6 m3 my 1 per square meter which is greater than the vertical flux of water at the same depth from compaction of the deeper basin fill the average volumetric rate of water expulsion is 120 km3 my 1 across the whole basin biogenic silica is particularly rich in neogene successions in high latitude and equatorial regions and where silica reaction zones are identified they should be factored into sediment compaction and fluid flow histories

quartz types in the upper pennsylvanian organic rich cline shale wolfcamp d midland basin texas implications for silica diagenesis porosity evolution and rock mechanical properties

kinematic subsurface stormflow this paper builds on the analysis of henderson and wooding 1964 in comparing simplified models of subsurface stormflow for the case of a sloping soil mantle in which the hydraulic conductivity is constant throughout it is shown that models based on a kinematic wave formulation may be good approximations for those based on the extended dupuit forchheimier assumptions for values of the nondimensional parameter 4i cos k sin2 less than about 0 75 in terms of predicting both water table profiles and subsurface stormflow hydrographs by using this critical value of the range of values of slope angle and saturated hydraulic conductivity for which the kinematic approximation is valid can be specified a comparison is made with slope angles and hydraulic conductivities at field sites where subsurface stormflow has been shown to be an important component of catchment storm response it is concluded that the kinematic approximation may be useful for cases of practical interest

diagenesis and distribution of sterenes in late miocene to pliocene marine siliceous rocks from horonobe hokkaido japan abstract late miocene to pliocene marine siliceous rocks from horonobe hokkaido japan are rich in sterenes and steradienes diagenetic degradation and transformation of these components in sediments from the wakkanai and koetoi formations were studied using core samples from boreholes hdb 3 and hdb 4 drilled by the japan atomic energy agency the palaeotemperatures of the rocks were estimated to be in the range 30 60 c on the basis of the transformation of opal a to opal ct and the present day geothermal gradient in the horonobe region concentrations of steradienes and sterenes decrease rapidly in the range 45 60 c the significant increase in sterane concentration in the same temperature range shows that part of the steranes is derived from sterenes and steradienes the sterane sterene ratios of the c27 c28 and c29 components change similarly with increasing maturity indicating that the ratio can be a useful indicator of palaeotemperature in the early diagenetic stage for sterenes and steranes the relative abundance of the c27 c28 and c29 components is quite similar through both boreholes showing that it is not significantly affected by the diagenetic transformation of sterenes

a conventional straddle sliding packer system as a borehole extensometer monitoring shear displacement of a fault during an injection test abstract a constant head step injection test using a conventional straddle packer system was performed for a normal fault in siliceous mudstone the test applied a new method whereby axial displacements of isolated test sections in a borehole during injection are monitored by measuring the pressures of sliding packers and the pore pressure in the test section the measured pressures and axial displacement and the injection flow rate were used to estimate the hydraulic aperture shear displacement normal compliance normal stress shear stiffness and hydraulic dilation angle of the fault during the test the injection successfully yielded a large shear displacement during normal faulting of up to 13 3 49 5 mm including the estimation error which left residual shear displacement of 2 8 10 4 mm after a remarkable shear slip event the shear stiffness during faulting is estimated to be 2 3 107 to 8 4 107 pa m 1 considering the estimation error which is consistent with empirically predicted values based on previous studies the hydraulic dilation angle was inferred to be effectively zero as the residual shear displacement did not leave any increase in hydraulic aperture the experimental method applied here does not require specialized equipment and could aid in the investigation of the hydromechanical behavior of subsurface fractures or aquifers

can surface samples be used to infer underground permeability structure a test case for a neogene sedimentary basin in horonobe japan abstract we measured gas permeability of neogene sedimentary rocks from wakkanai koetoi and yuchi formations in the horonobe area in northern hokkaido japan measurements were done at room temperature and during pressure cycling to simulate underground conditions fresh intact samples from surface outcrops yielded a similar range of permeabilities as did intact samples from drill cores within lithological variations comparison of laboratory and in situ measurements has revealed that the permeability of wakkanai formation middle to late miocene siliceous mudstone from in situ measurements is bounded by the permeability of brecciated specimen on the upper side and by the permeability of intact specimens on the lower side fragments in fault breccia are smaller than sample size and laboratory data should be applicable to natural fault rocks permeability of fractured specimens falls in between those upper and lower bounds and complex scale issues will not be important in determining upper and lower bounds of permeability the hydraulic conductivity values from in situ tests for koetoi formation late miocene to pliocene diatomaceous mudstone are similar to those of the gas permeability of intact specimens effects of faults and fractures on permeability seems to be minor for this formation and this was confirmed by permeability measurements with fractured samples the hydraulic conductivity values from in situ tests for yuchi formation are lower than estimates from laboratory tests by within an order of magnitude thus permeability measurements in laboratory on fresh surface samples intact fractured and brecciated combined with geological survey on the development of faults and fractures leads to quantitative estimates even if not complete of underground permeability structures

influences of soil water characteristic curve on rainfall induced shallow landslides the analysis of slope instability induced by rainfall was usually performed using the main drying curve as the measurement of the main wetting curve is a more time consuming and costly task in this study the influences of the main drying and wetting curves on rainfall induced shallow landslides are examined three designed scenarios and a real case scenario are used to conduct this examination the prediction of shallow landslide occurrence is related to the main drying and wetting curves due to the strong relation between groundwater pressure head and hysteresis effect the main wetting curve may have a less minimum landslide triggering rainfall amount and a less rainfall duration threshold for landslide occurrence than the drying wetting curve for safety s sake an underestimation of shallow landslide occurrence may be produced by the commonly used main drying curve in addition besides the shallow landslide occurrence the failure depth and the time to failure are also influenced by the main drying and wetting curves the hysteresis effect should be taken into account for assessing rainfall induced shallow landslides

ultrasonic velocities of opaline rocks undergoing silica diagenesis experimental results of laboratory measurements at ultrasonic frequencies on dry opaline rocks are documented from the monterey formation a siliceous unit in the san joaquin basin in these samples the silica is primarily biogenic opal a in origin but progressively alters to opal ct and then quartz with depth the diagenetic transitions are accompanied by a marked porosity reduction compressional and shear wave velocities were measured on core plugs at effective reservoir pressure experimental results on samples from the opal a opal ct transition and the opal ct quartz transition show very little pressure dependence of elasticwave velocities when their elastic moduli are normalized by those of the solid phase the moduli porosity trend is very close to that of chalk and in the lower porosity domain of some clean sandstones

modelling a mine by test at the mont terri rock laboratory switzerland abstract an instrumented mine by test was conducted at the mont terri rock laboratory switzerland in 1997 1998 to assess issues associated with tunnel excavation in a middle jurassic claystone known as the opalinus clay excavation induced stresses resulted in unusually large deformations and the development of an excavation disturbed zone edz around the tunnel where the observed dominant mode of yielding consisted of extensional fracturing from field and laboratory observations it has been observed that opalinus clay exhibits responses that often are not represented adequately by linear elastic or elasto plastic models in particular strong non linear elastic behaviour at low stresses was observed in laboratory tests this behaviour has been captured by a phenomenological based model known as the stress dependent modulus sdm model the concepts of the sdm model have been extended to a piece wise pore pressure formulation that captures the hydromechanical rockmass response these models were implemented into a finite difference method numerical code and used to simulate the short term deformations and pore pressure response of the ed b mine by test these simply calibrated models provided a reasonable fit to the field data particularly in regions of unloading where rockmass deformations were not dominated by dilation

diagenesis and distribution of acyclic isoprenoid hydrocarbons in late miocene to pliocene marine siliceous rocks from horonobe hokkaido japan abstract a sequence of late miocene to pliocene siliceous mudstones from boreholes hdb 3 and hdb 4 from horonobe hokkaido japan is homogeneous and useful for the study of diagenetic degradation and transformation of sedimentary organic matter using these siliceous mudstones the diagenetic change in acyclic isoprenoid hydrocarbons was investigated the palaeotemperatures of the samples were estimated to be in the range 30 60 c on the basis of the silica mineral transformation and the present day geothermal gradient in the region the relative abundances of pristane to pristenes and phytane to phytenes increase drastically with depth the remarkable changes in pristane pristene and phytane phytene occur in a temperature range of about 35 50 c the relative abundances could be potential parameters for palaeotemperature analysis of immature sedimentary rocks remarkable increases in pristane and phytane concentration with maturity show that in addition to extractable free pristenes and phytenes bound acyclic isoprenoids are the major source of pristane and phytane pristane phytane and pristenes phytenes are nearly constant through the entire boreholes showing that the relative abundance of the precursor c 19 c 20 acyclic isoprenoids was determined at the time of deposition and or in the early stage of diagenesis pristene phytene as well as pristane phytane could be useful parameters for assessing palaeodepositional environment

numerical modeling of rainstorm induced shallow landslides in saturated and unsaturated soils for the assessment of shallow landslides triggered by rainfall the physically based model coupling the infinite slope stability analysis with the hydrological modeling in nearly saturated soil has commonly been used due to its simplicity however in that model the rainfall infiltration in unsaturated soil could not be reliably simulated because a linear diffusion type richards equation rather than the complete richards equation was used in addition the effect of matric suction on the shear strength of soil was not actually considered therefore except the shallow landslide in saturated soil due to groundwater table rise the shallow landslide induced by the loss in unsaturated shear strength due to the dissipation of matric suction could not be reliably assessed in this study a physically based model capable of assessing shallow landslides in variably saturated soils is developed by adopting the complete richards equation with the effect of slope angle in the rainfall infiltration modeling and using the extended mohr coulomb failure criterion to describe the unsaturated shear strength in the soil failure modeling the influence of rainfall intensity and duration on shallow landslide is investigated using the developed model the result shows that the rainfall intensity and duration seem to have similar influence on shallow landslides respectively triggered by the increase of positive pore water pressure in saturated soil and induced by the dissipation of matric suction in unsaturated soil the rainfall duration threshold decreases with the increase in rainfall intensity but remains constant for large rainfall intensity

mechanical strength of the transition zone at the boundary between opal a and opal ct zones in siliceous rocks abstract in a massive siliceous mudstone at the site of the horonobe underground research laboratory in hokkaido japan a hard part having a very high unconfined compressive strength occurs at the top of siliceous mudstone opal ct zone at the boundary with the overlying diatomaceous mudstone opal a zone bulk chemical data does not indicate additional silica cementation or differences in mineralogy in the hard part compared with the remainder of the siliceous mudstone the hard part corresponds to a transition zone between opal a and opal ct where the two phases coexist sem images show that microcrystalline opal ct precipitates within pore spaces in the pre existing intricate diatom supported framework of the transition zone below this zone the framework is replaced by aggregations of relatively fine and equigranular opal ct the strength of the hard part probably reflects the strong framework cementation due to the coexistence of opal a and opal ct consequently the transition zone between opal a and opal ct is generally strong and brittle and if it tectonically deformed it could act as a fluid conduit

the role of low temperature organic matter diagenesis in carbonate precipitation within a marine deposit abstract carbonate minerals in veins can record paleo hydrogeological information that enables the reconstruction of groundwater history this paper investigates the cause of differences in the occurrence of carbonate veins in the koetoi and wakkanai formations both neogene mudstone units in northwestern hokkaido from the perspective of controls on co2 supply from the alteration of organic matter carbonate veins are rare in the koetoi formation but are widespread in the wakkanai formation this area is a region of oil and gas accumulation where deep groundwater is saturated mainly with ch4 and co2 the results show high 13c values in co existing ch4 32 6 and co2 31 0 gases an investigation of 13c d systematics among these gases indicates that isotopic fractionation was caused by microbial co2 reduction although total organic carbon content in the koetoi formation decreases with increasing depth total organic content in the wakkanai formation remains roughly constant with depth furthermore although 13c values also show depth dependence values from the wakkanai formation are higher than those from the koetoi formation this 13c enrichment could be explained by rayleigh fractionation in a closed system based on these results the processes behind the formation of the carbonate veins can be summarized as follows carbon dioxide behavior is thought to play an important role with respect to carbonate formation because co2 abundance is closely linked to ph and pressure in shallow sedimentary rocks such as the koetoi formation that have started to experience diagenetic alteration of organic matter co2 in groundwater is supplied by microbial decomposition of organic matter and is reduced to ch4 by methanogens in deep sedimentary rocks such as the wakkanai formation that have undergone diagenesis but have only experienced moderate temperatures so that thermal decomposition of organic matter has not yet begun microbial degradation of organic matter has proceeded too far for any more co2 to be produced thus carbonate precipitation is initiated when ph rises due to microbial co2 reduction the contrast between the occurrence of carbonate veins in the koetoi and wakkanai formations can be explained by our results which can also be applied to general carbonate behavior in marine sedimentary rocks

the mechanical behaviour of weak mudstone opalinus clay at low stresses abstract over the last 10 years argillaceous rocks mudrocks such as the jurassic claystone opalinus clay have gained acceptance as a potential host formation for geological disposal of nuclear waste observations from tunnels in opalinus clay at the mont terri rock laboratory switzerland suggest that the excavation induced response is not linear elastic the micro structure of the opalinus clay has been identified as a source for this response it has been demonstrated that diagenetic processes over the last 180 ma have been responsible for the formation of strong diagenetic bonds locking latent strain energy into the micro structure of opalinus clay a conceptual model of the micro structure including the effects of diagenetic processes has been developed as a framework to interpret the mechanical behaviour of the opalinus clay samples recovered at mont terri rock laboratory have been subjected to processes that have resulted in bond breakage and the release of locked in latent strain energy this tends to reduce the strength and deformation properties of samples and induces low stiffness non linearity of the stress strain curve at low stress levels numerical modelling of the sampling stress path at mont terri rock laboratory shows that unloading was the dominant factor resulting in this response as a result samples can shed light on the unloading response of the rockmass to excavation this non linear behaviour has been quantified by means of routine laboratory compressive tests

preliminary result from pore pressure monitoring on an unstable clay slope abstract we monitored positive pore water pressure in a clay slope in the apennines to investigate how rainfall influences the pore pressure distribution along the soil profile and consequently affects slope stability conditions data refers to the first season of monitoring activities august 2001 june 2002 the study site is located at the head of a complex landslide where incipient shallow failures are visible along the slope the preliminary analysis of pressure data allowed to point out consistent trends which manifested throughout 11 months during the cold and wet season saturation always extends close to the ground surface the presence of prefertial flow path in the sub surface can only explain anomalous response of some sensors or substantial differences between buried at similar depths

field evidence of pore pressure diffusion in clayey soils prone to landsliding 1 the hydrologic behavior of shallow weathered soils commonly determines the propensity for slope failure here we use laboratory data and field data collected by an automated monitoring system to assess the character of pore water pressure responses in a natural clay slope subject to intermittent rainfall although we did not measure pore pressure distributions that triggered slope failure we obtained three years of field data that provided reliable and largely reproducible documentation of transient pore pressure responses at depths of tens of centimeters to a few meters below the ground surface moisture and pressure sensors recorded relatively fast transient responses to precipitation the speeds of pore pressure pulses advancing downward in the saturated zone were much larger than those of advective fronts driven by gravity and the amplitudes of the pulses attenuated with depth statistical assessment of 129 pressure head responses demonstrates that this behavior is consistent with predictions of a linear one dimensional pore pressure diffusion model however the model best simulates measurements if diffusivity is treated as a calibration parameter and if initial moisture conditions match model assumptions for regional assessment of slope stability the predictive accuracy of the linear diffusion model is limited by inherent uncertainties in defining the initial conditions and in assigning the values of hydraulic parameters

quarries and transportation routes of angkor monument sandstone blocks sandstone blocks are the main construction materials used in the angkor monuments in cambodia however a thorough study of the quarries has not yet been carried out we conducted a field investigation of sandstone quarries from the angkor period at the southeastern foot of mt kulen which is approximately 35 km northeast of the angkor monuments as a result we discovered more than 50 sandstone quarries on the basis of the measurements of magnetic susceptibilities and thicknesses step heights we found that they were quarried at different times these four quarrying areas were identified as the quarries d to g inferred by uchida et al 2007 in addition we investigated a canal that was identified on satellite images connecting quarry sites at the foot of mt kulen to the angkor monuments the field investigation suggests a high probability that the canal was used for the transportation of sandstone blocks from mt kulen

elastic and shear moduli of coal measure rocks derived from basic well logs using fractal statistics and radial basis functions abstract gamma ray density sonic and core logs obtained from two boreholes drilled over a longwall panel in southwestern sw pennsylvania were analyzed for formation boundaries log derived porosities and densities and for rock elastic properties from sonic transit times gamma ray gr and density logs dl were analyzed using univariate statistical techniques and fractal statistics for similarity and ordering of the log data in depth a fourier transformation with low pass filter was used as a noise elimination filtering technique from the original logs filtered data was tested using basic univariate and fractal statistics rescaled range r s and power spectrum ps analysis to compare the information characteristics of the filtered logs with the original data the randomness of log data in depth was analyzed for fractional gaussian noise fgn or fractional brownian motion fbm character a new prediction technique using radial basis function rbf networks was developed to calculate shear and young s moduli of the formations when sonic logs are not available for this approach the filtered logs were used as input to an rbf based upon a combination of supervised and unsupervised learning the network was trained and tested using rock elastic properties calculated from the sonic log of one of the boreholes the network was used to predict the elastic and shear moduli of the coal measure rocks over a longwall coal mine in sw pennsylvania this approach demonstrated that it could be used for prediction of elastic and shear moduli of coal measure rocks with reasonable accuracy

evaluation of landfill disposal boundary by means of electrical resistivity imaging this paper deals with an employment of electrical resistivity imaging eri for survey of leachate content on the waste disposal site in northern israel the research consisted of conducting ten eri lines and drilling investigation wells data simulation used a 2d earthimager inversion program analysis of 2d eri interpretation results shows that determination of the boundary between the landfill body bottom intensively saturated with leachates and underlying layers of highly water saturated fat nonconsolidated clays presents a challenge however statistical analysis of eri data indicates that standard deviation and confidence interval of a set of resistivity data measured in the landfill body are significantly larger than those in underlying clays moreover maximum changes of these parameters are found on the boundary between landfill body and underlying soil thus reflecting natural differences in scattering of resistivity data measured in these two objects

focused fluid flow along faults in the monterey formation coastal california fluid flow in fractured siliceous mudstone of the miocene monterey formation of california is inferred to be highly focused toward map scale faults that locally contain extensive amounts of carbonate and minor silica cement the distance of cross stratigraphic flow as inferred based on the strontium isotopic composition of carbonate fault cement is close to the thickness of the monterey formation of 700 m in one of two study locations jalama beach and less than the formation thickness at another location arroyo burro beach fluid is thus derived from within the monterey formation rather than from underlying older units based on mass balance estimates of the fluid volume required for fault cementation at jalama beach the minimum distance of formation parallel flow into the fault zone is 4 km and possibly 12 km the inferred distance of flow parallel to the formation into this fault thus exceeds the distance of cross formational upward flow along the fault by at least a factor of six the mass balance estimate requires that fluid flow along the fault is channeled into a pipe shaped conduit rather than distributed along fault strike fluid flow from the surrounding formation into fault pipes is inferred to follow a radial rather than uni or bilateral flow symmetry using bedding confined sets of extension fractures and stratabound breccia bodies radial fluid flow toward fault pipes requires fairly isotropic fracture permeability for flow along bedding and a low permeability across bedding the inferred flow geometry illustrates the combined effect of fault permeability structure permeability anisotropy of the surrounding formation and hydraulic head distribution in controlling basinal fluid flow in faulted sequences

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

non linear soil stiffness in routine design soil stress strain behaviour is highly non linear and this has an important influence on the selection of design parameters for simple routine geotechnical calculations non linear behaviour can be characterized by rigidity and degree of non linearity and these can be determined from measurements of very small strain stiffness peak strength and failure strain very small strain stiffness can be found from measurements of shear wave velocity in situ or in laboratory tests peak strength and failure strain can be measured in routine laboratory tests but are strongly influenced by initiation of shear bands the important non linear stiffness parameters for soil are related to its composition and to its current state back analyses of the load settlement behaviour of full scale and model foundations demonstrate the influence of non linear soil behaviour variations of stiffness with settlement calculated from full scale and model foundations agree well with non linear soil stiffnesses based on rigidity and d

influence of rock composition on kinetics of silica phase changes in the monterey formation santa barbara area california the diatomaceous deposits of the monterey formation along the santa barbara coast were subjected to temperatures and burial depths that increased westward after deposition as a result the silica phase in originally similar laterally equivalent strata generally changed westward from biogenous opal a to diagenetic opal ct to diagenetic quartz in individual beds at the same stratigraphic level however silica phases changed at various temperatures producing a transformation or kinetic sequence related to variations in the ratio of silica to detrital minerals compared to silica in rocks with minor detrital minerals in rocks with progressively more abundant detrital minerals 1 opal ct formed progressively later 2 the initial d spacing of opal ct was progressively smaller and 3 quartz formed progressively earlier comparison of associated calcareous dolomitic and carbonate free rocks with equal silica detrital ratios shows that carbonates did not significantly affect rates of silica diagenesis in the vast majority of rocks in carbonate bearing rocks with silica detrital ratios 8 however some 2 to 10 quartz formed early in diagenesis probably prior to opal ct formation in addition atypical quartz cherts formed locally in carbonate bearing strata by pore filling and replacement early in diagenesis possibly before widespread opal ct formation

hydromechanical modeling of stress pore pressure and porosity evolution in fold and thrust belt systems we present coupled critical state geomechanical fluid flow simulations of the evolution of a fold and thrust belt in nw borneo our modelling is the first to include the effects of both syntectonic sedimentation and transient pore pressure on the development of a fold and thrust belt the present day structure predicted by the model contains the key first order structural features observed in the field in terms of thrust fault and anticline architectures stress predictions in the sediments show two compressive zones aligned with the shortening direction located at the thrust front and back limb between the compressive zones near to the axial plane of the anticline the modelled stress field represents an extensional regime the predicted overpressure distribution is strongly influenced by tectonic compaction with the maximum values located in the two laterally compressive regions we compared the results at three notional well locations with their corresponding uniaxial strain models the 2d thrust model predicted porosities which are as much as 7 5 lower at 2 5 km depth and overpressures which are up to 6 4 mpa higher at 3 km depth these results show that one dimensional methods are not sufficient to model the evolution of pore pressure and porosity in contractional settings finally we performed a drained simulation during which pore pressures were kept hydrostatic the predicted geological structures differ substantially from those of the coupled simulation with no thrust faulting these results demonstrate that pore pressure is a key control on structural development

petrology and diagenetic changes of neogene siliceous rocks in northern japan abstract diagenetic changes in textures and mass properties of neogene marine noncalcareous siliceous rocks corresponding to silica phase transformations opal a opal ct quartz were studied in subsurface and surface sections of northern japan in opal a diatomite siliceous tests are well preserved no cementation is observable and pores exist chiefly as inter and intragranular micropores 2 10 during the opal a to opal ct transformation siliceous tests are extensively dissolved to form fine aggregates of opal ct in matrix and cement of opaline porcelanite an abrupt decrease of as much as 15 in porosity occurs between opal a and opal ct zones in subsurface sections a decrease which may be due to the destruction of intragranular pores in siliceous tests by dissolution ultramicropores 10 as molds and chambers of siliceous tests in quartzose porcelanite porosity of neogene noncalcareous siliceous rocks in subsurface sections of northern japan gradually decreases with the increase of burial depth and silica phase transformations have a relatively small effect on it this gradual decrease in porosity which corresponds well to that of neogene mudstone and clean fine grained sandstone indicates that little additional silica cementation occurs during burial iijima and tada 1981 at a depth of 4 5 km and a temperature of 130 c quartzose porcelanite holds porosity of 10 15 burial depth of around 10 km might be required to form dense quartzose chert without porosity by burial diagenesis of siliceous rocks if extrapolating from the burial depth porosity relation this depth is too large some additional mechanisms are required ther than mechanical compaction silica phase transformations and clay alteration pressure solution reprecipitation of quartz is the most probable one

application of direct fitting mass integral and multirate methods to analysis of flowing fluid electric conductivity logs from horonobe japan 1 the flowing fluid electric conductivity ffec logging method is an efficient way to provide information on the depths salinities and inflow strengths of individual conductive features intercepted by a borehole without the use of specialized probes using it in a multiple flow rate mode allows in addition an estimate of the transmissivities and inherent far field hydraulic heads in each of the conductive features the multirate method was successfully applied to a 500 m borehole in a granitic formation and reported recently the present paper describes the application of the method to two zones within a 1000 m borehole in sedimentary rock which produced for each zone three sets of logs at different pumping rates each set measured over a period of about 1 day the data sets involve several complications such as variable well diameter gradual water level decline in the well during logging possible fluid flow through the unfractured rock matrix and effects of drilling mud various techniques were applied to analyze the ffec logs direct fitting mass integral and the multirate method mentioned above in spite of complications associated with the tests analysis was able to identify 44 hydraulically conducting fractures distributed over the depth interval 150 775 m below ground surface the salinities in fec and transmissivities and hydraulic heads in dimensionless form of these 44 features were obtained and found to vary significantly among one another these results were compared with transmissivity and head values inferred from eight packer tests that were conducted in this borehole over the same depth interval ffec results were found to be consistent with packer test results thus demonstrating the robustness of the ffec logging method under nonideal conditions

the role of bedding in the evolution of meso and microstructural fabrics in fault zones abstract to investigate the role of bedding in the evolution of meso and microstructural fabrics in fault zones detailed microscopic mineralogical and geochemical analyses were conducted on bedding oblique and bedding parallel faults that cut a folded neogene siliceous mudstone that contains opal ct smectite and illite an analysis of asymmetric structures in the fault gouges indicates that the secondary fractures associated with each fault exhibit contrasting characteristics those of the bedding oblique fault are r 1 shears whereas those of the bedding parallel fault are reactivated s foliation the bedding oblique fault shows the pervasive development of s foliation lacks opal ct and has low sio 2 tio 2 ratios only in gouge whereas the bedding parallel fault exhibits these characteristics in both gouge and wall rocks the development of s foliation and the lack of silica can result from local ductile deformation involving the sliding of phyllosilicates coupled with pressure solution of opal ct although such deformation can occur in gouge the above results indicate that it may occur preferentially along bedding planes preceding the formation of a gouge slip surface thus in sedimentary rocks that contain phyllosilicates and soluble minerals bedding can influence the rheological evolution of meso and microstructural fabrics in fault zones

drainage from a uniform soil layer on a hillslope note 22 631 634 reference eflum article 1986 001 record created on 2005 09 08 modified on 2017 02 23

unsaturated and saturated flow through a thin porous layer on a hillslope the subsurface stormflow in a layer of porous earth overlying an impervious hill is investigated in the case when the thickness of the layer is small compared to a typical hill dimension if the infiltration rate at the surface is low and varies slowly with time the head is approximately constant along normals to the hillslope and the flow in both the saturated and unsaturated regions is described by a simple kinematic wave equation solutions of this equation describe the spatial and temporal development of the water table as well as the flow in the saturated and unsaturated regions a numerical example is given