spatial modeling of discontinuous geologic attributes with geotechnical applications geologic data obtained by drilling investigations field measurements and laboratory tests are irregularly distributed with respect to location both horizontally and vertically spatial discontinuities impact soil classification hydraulic conductivity and chemical content in this study a three dimensional modeling method which combines the optimization principle method and a stochastic simulation method was developed optsim this method consists of three steps the transformation of geologic attributes into binary 0 or 1 under certain thresholds the three dimensional interpolation of these transformed binary data and the construction of conditional cumulative distribution functions ccdf by repeatedly changing the threshold and interpolation analysis the monte carlo method was then used to inversely determine the attributes from the constructed ccdfs three types of attribute expressed by value code and class were examined the optsim was applied to spatial modeling of geotechnical structures in the kumamoto plain southwest japan using two kinds of data lithologic units and physical soil properties resistivity data obtained by electric logging and the locations of screens were linked to geologic distribution the constructed model contributed to the location of chief aquifers and estimates of amount of shallow groundwater a combination of granular composition n value and water content was examined transgression and regression patterns following the last glacial stage were also inferred through this analysis in both applications discontinuities in lithologic units and soil properties resulting from fault movements and sea level changes were successfully expressed in the distribution models

water balance modelling in lateritic terrain an analytical approximate model for unsaturated flow in a spatially variable field coupled with infiltration and evapotranspiration at the upper boundary and a fluctuating water table at the lower boundary has been developed the unsaturated flow equations depend on parameterizations of and k they are based on the notion of a moving discontinuous front the field heterogeneity refers to saturated hydraulic conductivity only horizontal variability is considered and the flow medium is approximated as a set of uncorrelated vertically homogeneous columns expectations and variances obtained with this approach have been compared with observations of the field hydrological processes three important aspects of the hydrology in this lateritic terrain are rapid water table response hortonian surface runoff generation and soil suction variability the stochastic conceptualization used explains to a high degree these characteristics although some limitations are demonstrated

hydromechanical behavior of a deformable rock fracture subject to normal stress lbl 12297 preprint to be published in the journal of geophysical research hydromechanical behavior of a deformable rock fracture subject to normal stress y w tsang and p a witherspoon january 1981 two week loan copy this is a library circulating copy which may be borrowed for two weeks for a personal retention copy call tech info diu is ion ext 6782 prepared for the u s department of energy under contract w 7405 eng 48

rainfall induced differential settlements of foundations on heterogeneous unsaturated soils this study stochastically investigates the rainfall induced differential settlement of a centrally loaded rigid strip foundation on an unsaturated soil with spatially varying values of either preconsolidation stress or porosity the differential settlement between the two foundation ends is calculated at various times during rainfall by way of a coupled hydro mechanical finite element analysis the barcelona basic model describes the mechanical behaviour of the soil and the van genuchten relationships describe water retention and permeability the variability of soil properties is modelled by means of random fields with spatial correlation in the framework of a monte carlo simulation the study demonstrates that the occurrence of rainfall induced differential settlements can be consistently analysed using concepts of unsaturated soil mechanics and random field theory results show that differential settlements can be vastly underpredicted or even completely missed if random heterogeneity and parti

analysis of spatial variability of spt penetration resistance in collapsible soils considering water table depth abstract geostatistical kriging approach was used for mapping of water table depth and for checking its influence on penetration resistance observed in standard penetration test spt geostatistical mapping was based on a compartmentalisation of 204 spt records in two main groups using monthly and yearly rainfall marks as a segregation criterion six maps produced at 1 10 000 scale were achieved as follows water table depth variation and penetration resistance variation at the depths of 1 5 6 0 8 5 11 0 13 5 m greater variations of the penetration resistance in terms of increase and reduction of resistance were observed at the depths of 6 0 and 8 5 m

a generic approach to soil structure interaction considering the effects of soil heterogeneity the longitudinal variation of soil properties has a major influence for many types of structure including pavements buried pipes raft foundations and railways as it induces stresses and or displacements that cannot be predicted when assuming soil homogeneity a set of simple numerical models has been developed to describe how soil structure interaction can be influenced by soil variability these models include a a description of the soil spatial variability within the frame of geostatistics where the correlation length of soil properties is the main parameter and b a mechanical description of the soil structure interaction which depends on the structure resting on the ground there are some differences between a more or less rigid raft on piles a set of buried pipes with more or less flexible connections and a hyperstatic beam but the basic principles of mechanics are similar in all these cases several very general conclusion are drawn a soil heterogeneity induces effects differen

kinematic wave approximation to infiltration into soils with sorbing macropores infiltration into soils with macropores is treated as two domain flow the first domain is the soil matrix in which water is subjected to capillarity and infiltration is approached by philip s sorptivity concept the second domain is the soil macropore system in which water moves only under gravity and flow is approached by kinematic wave theory a sink function with respect to flow in the macropore system accounts for water sorption by the soil matrix the two domain flow model is then applied to infiltration into a block of undisturbed soil containing macropores

influence of soil spatial variability on possible dysfunction and failure of buried pipe case study in pessac city france malfunctions and failures of buried pipes such as oil and gas transmission networks are caused primarily by heterogeneous geotechnical conditions and spatial variability of soil properties they are the main source of uncertainty in the choice of the design properties these heterogeneity and variability can be well detected using the geotechnical and geophysical investigations on a construction site such as pressuremeter and soil resistivity tests in this study a geostatistical analysis of soil modulus es coupled with geotechnical and geophysical data of a real construction site in france city of pessac is conducted to improve the mechanical characteristics of soil on the construction site the collocated ordinary cokriging between twelve values of es and 272 values of soil resistivity was used to model the spatial variability of young s soil modulus from this two different modelings using the winkler model with pipe soil interaction were applied in order to analyze the longitudinal behavior of buried steel pipes an analytical modeling to deal with uncertainty of es and a numerical modeling to deal with spatial variability of es a comparison between numerical and analytical outcomes highlights the major influence of spatial variability on the uncertainties of the bending moment and differential settlement of buried steel pipes finally results show the significant influence of the soil spatial variability on the longitudinal behavior of buried pipes thus special consideration is necessary to adapt the buried pipe design to a construction site where soil properties vary spatially in order to reduce their possible dysfunction and failure

vlf resistivity mapping and verticalization of the electric field1 tabbagh a bendritter y andrieux p decriaud j p and guerin r 1991 vlf resistivity mapping and verticalization of the electric field geophysical prospecting 39 10831097 for over 20 years powerful vlf transmitters have been used as electromagnetic sources for subsurface investigations in mining exploration measurements initially concerned the vertical component of the magnetic field or the inclination of the field and were later extended to measurement of the horizontal electric field in the direction of the transmitter to determine the resistivity of the terrain measurement of the electric field is usually performed with electric lines grounded or not with lengths of at least 5 m this paper presents the concept of a vlf resistivity meter with a very short electric sensor 1 m and the results obtained with it this technique improves the measurement of the electric field which is in principle a point value it also permits a higher spatial sampling rate and by closely linking the electric sensor with the magnetic sensor on a lightweight mount makes it possible for the instrument to be used by a single operator in addition transformation of the electric field data analogous to reduction to the pole in magnetism is proposed to correct the horizontal deformation of the anomalies created by polarization of the primary field comparison with direct current electrical measurements shows highly satisfactory correlations this transformation validated for vlf can be extended to any electrical or electromagnetic method using a uniform primary field i e gradient array in direct current or low frequency magnetotellurics we call this verticalization of the electric field resistivity measurements and mapping using the vlf frequency range can be applied not only to mining but also to a wide range of shallow geophysical studies hydrology civil

the geochemistry of co and cu in the kafue river as it drains the copperbelt mining area zambia abstract samples of the dissolved 0 45 m phases have been collected in the kafue river during a 1 year cycle within the mining area the concentrations of co cu and s in the river occasionally increase more than 100 times compared to concentrations upstream from the mining area the highest concentrations of dissolved cu 3 4 m and fe 4 2 m are found during high water discharge probably indicating a washout of leached weathering products from spoil heaps high levels of co appear to originate from one point source the location where the co ore is treated in the kafue river secondary mn and fe rich particles are formed on which co and cu respectively are enriched the elements associated to secondary fe and mn particles are enriched at the sediment surface in the river due to redox processes hence secondary particles and sorbed trace elements may be resuspended and transported further downstream in the river system however very high concentrations of cu 1 and co 0 1 in the sediment are caused by primary sulphides

a new geometrical model for non linear fluid flow through rough fractures summary fractures in rock mass are the main flow paths and introduce as a most important attribute in rock mass hydraulic behavior the non linear fluid flow through rock fractures was studied in this paper computational domain of an artificial three dimensional fracture is generated and used for cfd simulations both laminar and turbulent flow simulations were performed for a wide range of flow rates also a new non linear fluid flow formulation was developed on the basis of some geometrical and kinematical assumptions for fracture and fluid flow respectively based on comparison between simulation results and developed formulation a new geometrical model has been proposed for non linear fluid flow through rough fractures which suggests a polynomial expression like forchheimer law to describe the dependence of pressure drop on flow rate finally this model has been evaluated with experimental results of a fracture with different geometries the results show that the predicted pressure drop for turbulent flow simulation was roughly 3 17 more than those for laminar one at the reynolds number of 4 5 89 5 respectively moreover a good accuracy was found between the proposed model and turbulent flow simulation results these findings may prove useful for computational studies of flows through real rock fractures or inclusions in simulators for large scale flow in fractured rocks

geotechnical modeling at the city scale using statistical and geostatistical tools the pessac case france abstract in the context of the riviera project the building of a 3d geotechnical model at the city scale pessac france has been undertaken from several hundreds of boreholes and geotechnical tests it is first shown how the combination of the lithological information and of geotechnical results can improve thanks to bayesian statistics the knowledge of mechanical characteristics in the various alluvial terraces which can be encountered in this area secondly the upper and lower limits of the 3d model at the city scale are computed by improving an initial digital elevation model for the upper limit and by kriging under inequality constraints for the lower limit these limits border quaternary formations which are of interest for geotechnical applications in a third stage it is focused on the spatial modelling of the pressuremeter modulus the sequential indicator simulation method enables to obtain the spatial probability of occurrence of a given pressiometer modulus class coupled with other information the analysis of these statistical and geostatistical models makes possible to develop decision support tools such as to localise for instance areas more prone to the clay shrinkage swelling hazard

an experimental study of single and two phase fluid flow through fractured granite specimens triaxial tests on the two phase flow of air and water through fractured granite specimens were performed to discover whether the two phase fluid flow within rock fractures was laminar or turbulent the two phase flow characterization was carried out based on the macroscopic two phase steady state flow model and the homogeneous steady state flow model rock specimens with a single natural fracture joint roughness coefficient jrc 10 were tested using two phase high pressure triaxial rig experimental results show that the estimated reynolds numbers for various inlet fluid pressures are well below 1000 the findings of this study reveal that both single and two phase flow through rock fractures jrc 10 can be characterized as laminar flows at moderate inlet fluid pressures however for single phase air flow an increase in inlet air pressures may result in the formation of turbulent flow

comment on effective groundwater model parameter values influence of spatial variability of hydraulic conductivity leakance and recharge by j j gomez hernandez and s m gorelick

effect of soil variability on the bearing capacity of clay and in slope stability problems site specific geotechnical data are always random and variable in space in the present study a procedure for quantifying the variability in geotechnical characterization and design parameters is discussed using the site specific cone tip resistance data qc obtained from static cone penetration test scpt the parameters for the spatial variability modeling of geotechnical parameters i e i existing trend function in the in situ qc data ii second moment statistics i e analysis of mean variance and auto correlation structure of the soil strength and stiffness parameters and iii inputs from the spatial correlation analysis are utilized in the numerical modeling procedures using the finite difference numerical code flac 5 0 the influence of consideration of spatially variable soil parameters on the reliability based geotechnical deign is studied for the two cases i e a bearing capacity analysis of a shallow foundation resting on a clayey soil and b analysis of stability and deformation pattern of a cohesive frictional soil slope the study highlights the procedure for conducting a site specific study using field test data such as scpt in geotechnical analysis and demonstrates that a few additional computations involving soil variability provide a better insight into the role of variability in designs

depth of investigation in electromagnetic sounding methods the time or frequency at which the electromagnetic em response of a buried inhomogeneity can first be measured is determined by its depth of burial and the average conductivity of the overlying section it is relatively independent of the type of source or receiver and their separation the ability to make measurements at this time or frequency however depends on the sensitivity and accuracy of the instrumentation the signal strength and the ambient noise level these factors affect different em sounding systems in surprisingly different ways for the magnetotelluric mt method it is possible to detect a buried half space under about 1 5 skin depths of overburden the maximum depth of investigation is virtually unbounded because of high signal strengths at low frequencies transient electromagnetic tem soundings on the other hand have a limited depth of penetration but are less affected by static shift errors for tem a buried inhomogeneity can be detected under about one diffusion depth of overburden for conventional near zone sounding in which induced voltage is measured impulse response the depth of investigation is proportional to the 1 5 power of the source moment and ground resistivity by contrast if the receiver is a magnetometer step response system the depth of investigation is proportional to the 1 3 power of source moment and is no longer a function of resistivity magnetic field measurements may therefore be superior for exploration in conductive areas such as sedimentary basins far zone or long offset tem soundings are traditionally used for deep exploration the depth of investigation for a voltage receiver is proportional to the 1 4 power of source moment and resistivity and is inversely proportional to the source receiver separation magnetic field measurements are difficult to make at long offsets because instrumental accuracy limits the measurement of the very slow decay of the magnetic field frequency domain controlled source systems are ideally suited for sounding at the very shallow depths needed for engineering archaeological and groundwater applications because of the relative ease of extending the measurements to arbitrarily high frequencies and also because geometric soundings can be made at low induction numbers

simulation of weathered profiles coupled with multivariate block support simulation of the puma nickel laterite deposit brazil modelling and assessing spatial variability and uncertainty of mineral deposits is critical for both capital investments in mining projects as well as operational issues once a mine is developed however traditional approaches for modelling geological domains and geostatistical estimation provide smoothed representations of the pertinent deposit attributes ignore spatial variability and thereby can mislead downstream decisions spatial variability and related uncertainty in modelling mineral deposit characteristics of interest ranging from metal content and geological boundaries to geomechanical geotechnical rock properties can be modelled and quantified by stochastic spatial simulations this is demonstrated through a detailed step by step application to the puma deposit a major nickel lateritic asset in brazil part of the onca puma mining complex to integrate the variability of the regolith profiles of the deposit their thicknesses are calculated after an unwrinkling process is applied and the deposit is then jointly simulated using min max autocorrelation factors maf the realizations serve as geological boundaries within which ni co fe sio2 mgo and dry tonnage factor dtf are subsequently jointly simulated directly at block support scale the final result is a series of equally probable representations of the puma deposit which are used to quantify and assess the uncertainty about key aspects of the project at the puma deposit such as the uncertainty of the in situ resources documented herein and the strict control of the ore s quality that feeds the ferronickel processing plant the framework presented shows the advantages of the maf and direct block simulation approaches for the efficient joint simulation of spatially variant geological attributes of large deposits for industrial environments the methods presented are general new in the context of geotechnical and geomechanical engineering and can assist in the modelling of spatial variability and quantification of uncertainty linked to geotechnical rock properties and pertinent lithological boundaries

horizontal hydraulic conductivity of shallow streambed sediments and comparison with the grain size analysis results streambed horizontal hydraulic conductivity kh has a substantial role in controlling exchanges between stream water and groundwater we propose a new approach for determining kh of the shallow streambed sediments undisturbed sediment samples were collected using tubes that were horizontally driven into streambeds the sediment columns were analysed using a permeameter test pt on site this new test approach minimizes uncertainties due to vertical flow in the vicinity of test tube and stream stage fluctuations in the computation of the kh values ninety eight pts using the new approach were conducted at eight sites in four tributaries of the platte river east central nebraska usa the kh values were compared with the nondirectional hydraulic conductivity values kg determined from 12 empirical grain size analysis methods the grain size analysis methods used the same sediment samples as kh tests only two methods the terzaghi and shepherd methods yielded kg values close to the kh values although the sauerbrei method produced a value relatively closer to kh than other nine grain size analysis methods the values from this method were not as reliable as the methods of terzaghi and shepherd due to the inconsistent fluctuation of the average estimates at each of the test sites the zunker zamarin hazen beyer and kozeny methods overestimated kh while the slichter us bureau of reclamation usbr harleman and alyamani and sen methods underestimated kh any of these specific grain size methods might yield good estimates of streambed kh at some sites but give poor estimates at other sites indicating that the relationship between kg and kh is significantly site dependent in our study copyright 2011 john wiley sons ltd

uncertainty quantification of structural and geotechnical parameter by geostatistical simulations applied to a stability analysis case study with limited exploration data abstract there are many uncertain factors impacting stability analyses of rock structures quantification of these factors significantly impact the engineering decision making process some of these factors are spatially distributed within the geological domain and the quantification of the spatial uncertainty is beneficial for stability analysis of the structure this paper proposes an integrated methodology for a stability analysis of rock structure by incorporating spatially varying factors this research models two key factors one categorical structural parameter fault zones and one continuous geotechnical parameter rock quality designation rqd two geostatistical simulation algorithms i e sequential indicator simulation and sequential gaussian simulation are applied to quantify the spatial uncertainty by generating multiple equiprobable simulation maps of fault zones and rqd values a slope stability analysis is performed by modeling the spatially varying fault zones and rqd the proposed method is validated using a synthetic data set the results from the synthetic data show the stability value of the synthetic data closely match with stability value calculated from simulated data finally the proposed method is applied to a slope stability analysis for an open pit mine design where limited exploration data is available geostatistically simulated rqd maps from the case study mine are analyzed to determine a safe slope angle of 44 for the open pit mining operation the proposed method can be applied for quantifying other geotechnical risk and integrated within any stability analysis framework

bearing capacity prediction of spatially random c ϕ soils soils with spatially varying shear strengths are modeled using random field theory and elasto plastic finite element analysis to evaluate the extent to which spatial variability and cross correlation in soil properties c and affect bearing capacity the analysis is two dimensional corresponding to a strip footing with infinite correlation length in the out of plane direction and the soil is assumed to be weightless with footing placed on the soil surface theoretical predictions of the mean and standard deviation of bearing capacity for the case where c and are independent are derived using a geometric averaging model and then verified via monte carlo simulation the standard deviation prediction is found to be quite accurate while the mean prediction is found to require some additional semi empirical adjustment to give accurate results for worst case correlation lengths combined the theory can be used to estimate the probability of bearing capacity failure but also sheds light on the stoc

modeling heterogeneity of gravel sand braided stream alluvial aquifers at the facies scale abstract the coarse grained alluvial aquifers are recurrently considered as almost homogeneous and isotropic media nevertheless water flow through these sediments is controlled by internal architecture therefore a better knowledge is necessary to understand the effects of facies heterogeneity on the conductivity magnitude and anisotropy within these aquifers in this work we search interactions at the facies scale within a glacio fluvial aquifer among sedimentary heterogeneity distribution of permeability and anisotropy the case study concerns pleistocene sequences of the ticino basin northern italy where three model blocks dug into real sediments at a quarry site have been investigated at the meter scale these model blocks represent the most diffuse facies associations 1 sand gravel dunes 2 gravel bedforms and 3 poorly sorted mass gravity deposits facies maps with 2 cm resolution were obtained for each block and used to condition 3d geostatistical simulation of the sediment volumes with a hierarchical modification of sisim conductivities of samples were either measured with laboratory tests or estimated with empirical formulas conductivity values were finally introduced as input data into the numerical flow model to compute the upscaled tensor of equivalent conductivity at the model block scale the results of field infiltration tests were used to verify the outcomes of upscaling experiments which identified the primary influence on the most permeable facies open framework gravel on both conductivity magnitude and anisotropy ratio the latter property is unrelated to the abundance of this facies but is controlled by its spatial distribution within the blocks as the connectivity of open framework gravel increases model blocks become more anisotropic on the other hand the low permeable sand facies of dunes do not produce significant anisotropy at the block scale these results show the importance of introducing the hierarchical assemblage of different rank depositional units in conceptual aquifer models in addition we identified the most significant depositional units to forecast the spatial distribution of aquifer heterogeneity at different scales

groundwater transport of cu in laterites in zambia abstract the risk of transporting copper cu in near surface laterite with acid groundwater was studied down gradient of a newly constructed open mine in the north western province of zambia the assessment was based on results obtained from field and laboratory work and geochemical modeling large seasonal variations in the groundwater elevation is changing the subsurface water flow from a dominating darcy flow in the laterite during the rainy season to a dominating fracture flow in the deeper fractured gneiss in the dry season as the major groundwater flow occurs in the laterite and the low ph of the groundwater is also observed in the laterite mineralogical and sorption experiments were confined to this unit where the risk of a cu groundwater transport is highest the mineralogy of the laterite was studied using x ray analysis infrared and mossbauer spectroscopy and results revealed a homogeneous composition of strongly weathered primary silica minerals mainly quartz muscovite biotite and feldspars and secondary minerals dominated by disordered kaolinite iron oxide goethite hematite mixtures or solely goethite and minute amounts of vermiculite cu sorption to the laterite was determined from batch experiments using initial cu concentrations between 10 and 400 mg l and ph of 2 8 and 4 5 at ph 4 5 a maximum sorption capacity of 239 mg kg was found for aqueous equilibrium cu concentrations of 150 mg l for aqueous cu concentrations below 150 mg l a nearly linear sorption was observed with kd value of 18 cu sorption to the laterite is negligible for ph 2 8 the mineralogical study of the laterite suggests that cu predominately sorbs to the minerals iron oxides and kaolinite

reliability evaluation of shallow foundation bearing capacity on c φ soils as our understanding of soils has been steadily improving the characteristics of its variability can now be highlighted this has practically changed our geotechnical modus operandi from strictly deterministic models to semiprobabilistic or even strictly probabilistic models the latter are still to be regarded as experimental and cannot for the time being be used routinely in practical working applications however the ongoing continued research and study of these methods combine to develop their worth and bring out any drawbacks this paper proposes a possible application of probabilistic methods to the study of shallow foundations reliability with respect to their bearing capacity the study concerns a foundation on a soil characterized by effective cohesion c and friction angle considering possible values of correlation coefficients between them and taking into account the effects of vertical fluctuation scale the results show that higher reliability indexes are found when correlations betw

a water balance study in lateritic terrain the water balance of a 600 m2 field site on a lateritic hillslope in kerala southwest india has been studied during two southwest monsoon seasons surface runoff was of minor importance while infiltration and evapotranspiration were the major components amounting to approximately 2 3 and 1 3 of the rainfall respectively groundwater response was rapid involving fluctuations of several metres recharge mechanisms hypothesized are water movement via preferred pathways from the ground surface to the capillary fringe where rapid rise in groundwater level is brought about by a transmitted pressure pulse groundwater recharge was found normally to take place during the southwest monsoon season only the field study demonstrates that seasonal shallow groundwater recharge representing the major portion of the rainfall may be observed in this lateritic terrain in the humid tropics it indicates a good potential for further groundwater development moreover conditions are conducive to a considerable contribution to possible recharge to deeper aquifers the observed groundwater recharge is the result of a complex process on which further research will throw more light

a case study to assess the potential for saline soil development due to irrigation abstract with the help of a generalized conceptual model for the formation of saline soil we examine whether irrigation proposed for an area near lethbridge alberta will compound an existing salinity problem the geology of the site is characterized by weathered and non weathered tills which overlie cretaceous bedrock locally preglacial sands and gravels occur along the axes of two bedrock valleys beneath the site piezometric data define local groundwater flow from west to east following the regional topographic slope however the depth to the water table is extremely variable and controlled by the preglacial sand and gravel unit the existing problem of soil salinity which is restricted to the western part of the study area is caused by the high water table and large quantities of dissolved mineral mass in the groundwater in the central and eastern part of the area the water table occurs at depths greater than 20m and saline soils have not formed flow modeling along a two dimensional cross section confirms that the water table configuration and hence the distribution of saline soils is controlled by the preglacial deposits indications are that excess recharge due to irrigation will not result in a water table rise unless the quantity involved is considerably larger than the natural rate of recharge thus irrigation will not contributed to a marked increase in the size of the area affected by the saline soil

soil pipe contribution to steady subsurface stormflow flow through a saturated idealized hillslope with a single soil pipe was simulated using a finite difference solution to the equation for three dimensional darcian flow in saturated heterogeneous media the proportions of hillslope discharge originating from flow through the soil matrix and from flow through a soil pipe were determined considering such factors as the radius depth and length of the pipe pipe spacing and the length and slope of the hillslope results demonstrate that soil pipes can contribute a significant amount and in many instances the majority of total subsurface stormflow

preferential flow and the generation of runoff 1 boundary layer flow theory approaches to soil water flow which are based on the theory of potential flow often overestimate either the volume of flow or the response time at the hillslope scale when their results are compared with observations macropore flow is frequently thought to be the reason for the discrepancy between observations and model performance the expression macropore flow is considered to be too restricting it confines the rapid flow and transport processes to the easily observed channels concealing the more general question as to what degree potential flow theory adequately describes flow in porous media the application of potential flow theory to infiltration leads to the richards equations only when hydrodynamic dispersion of soil water and capillary potential are perfectly correlated in this paper a boundary layer infiltration model is presented which is based on kinematic theory it is also expanded to lateral flow in a sloping soil

geotechnical characterization of the upper pleistocene holocene alluvial deposits of roma italy by means of multivariate geostatistics cross validation results abstract we are presenting an attempt to evaluate the spatial variability of geotechnical parameters in the upper pleistocene holocene alluvial deposits of roma italy by means of multivariate geostatistics the upper pleistocene holocene alluvial deposits of roma are sensitive to high levels of geohazard they occupy a sizable and significant part of the city being the foundation for many monuments historical neighborhoods and archaeological areas and the main host of the present and future subway lines we have stored information from more than 2000 geotechnical boreholes crossing the alluvial deposits into a relational database for the present study only the boreholes with lithologic textural interpretation and geotechnical information were selected the set includes 283 boreholes and 719 samples which have a set of geotechnical information comprising physical properties and mechanical parameters techniques of multivariate statistics and geostatistics were combined and compared to evaluate the estimation methods of the mechanical parameters with special reference to the drained friction angle from direct shear test principal component analysis was applied to the dataset to highlight the relationships between the geotechnical parameters through cross validation analysis multiple linear regression kriging and cokriging were tested as estimators of cross validation demonstrates that the cokriging with granulometries as auxiliary variables is the most suitable method to estimate in addition to proving that cokriging is a good estimator of cross validation demonstrates that input data are coherent and this allows us to use them for estimation of geotechnical parameters although they come from different laboratories and different vintages nevertheless to get the same good results of cross validation in estimation it is necessary for granulometries to be available at grid points since this information being not available at all grid points it is expected that in the future textural information can be derived in an indirect way i e from lithologic textural spatial reconstructions

geotechnical survey and mechanical parameters in urban soils modelling soil variability and inferring representative values using the extension of lyon subway line d as a case study urban soils are generally heterogeneous and thus require for any project careful geotechnical evaluation considering the difficulty faced by geotechnical engineers in defining a model of the und

influence of spatial variability of permeability property on steady state seepage flow and slope stability analysis in recent years spatial variability modeling of soil parameters using random field theory has gained distinct importance in geotechnical analysis in the present study commercially available finite difference numerical code flac 5 0 is used for modeling the permeability parameter as spatially correlated log normally distributed random variable and its influence on the steady state seepage flow and on the slope stability analysis are studied considering the case of a 5 0 m high cohesive frictional soil slope of 30 degrees a range of coefficients of variation cov from 60 to 90 in the permeability values and taking different values of correlation distance in the range of 0 5 15 m parametric studies using monte carlo simulations are performed to study the following three aspects i e i effect ostochastic soil permeability on the statistics of seepage flow in comparison to the analytic dupuit s solution available for the uniformly constant permeability property ii strain and deformation pattern and iii stability of the given slope assessed in terms of factor of safety fs the results obtained in this study are useful to understand the role of permeability variations in slope stability analysis under different slope conditions and material properties c 2009 elsevier b v all rights reserved

a case study of a chemical spill polychlorinated biphenyls pcbs 2 hydrogeological conditions and contaminant migration the purpose of the second paper in this pair is to describe the hydrogeology and to account for the observed patterns of pcb contamination of the federal pioneer site in regina canada six major hydrostratigraphic units were identified from detailed test drilling and sampling from the surface downward these are a thin surface fill the regina clay the condie silt the till zone the interglacial silt and the regina aquifer system this latter unit is an important source of potable groundwater at present the nearest wells are hundreds of meters from the site the permanent water table is situated below the condie silt in sandy glacial till an active perched groundwater system has developed within the thin fill layer beneath the floor of the plant the extensive lateral flow of ground water in this zone has contributed significantly to the spreading of pcbs to at the site the pcbs have also moved downward through fractures in the regina clay and in the upper part of the condie silt it can be expected that capillary forces will halt the downward movement of inerteen 70 30 as fractures narrow or stop however the possible existence of fractures connecting the contaminated zone to the reginamore aquifer system or the potential for transport as a dissolved phase in the groundwaters may permit pcbs migrate downward to the aquifer or to flow laterally off site the most significant hazard represented by the spill is the potential for contamination of future water supply wells that may be placed near the site or aquifer contamination that could result if future drilling provides pathways for contaminants through poorly sealed wells or test holes less

assessment of alluvial aquifer heterogeneity and development of stochastic hydrofacies models for the hat yai basin in southern thailand in previous studies the groundwater flow models formulated for the hat yai basin were conventional and deterministic because the geologic heterogeneity of the alluvial aquifer system in the basin had not yet been assessed this paper describes an effort to develop hydrofacies models such that the spatial variability of the aquifer system can be represented in a systematic way variogram parameters that characterize the alluvial aquifer heterogeneity were determined based on these variogram parameters an indicator based geostatistical approach was used to develop hydrofacies models using sequential indicator simulation the hydrofacies models indicate three distinct aquifer units namely hat yai khu tao and kho hong aquifers which is in good agreement with a conceptual model and incorporates spatial variability as observed in field data from borehole logs the hydrofacies models can be used in groundwater modeling and simulations

spatial correlation structures of cpt data in a liquefaction site abstract in this paper the spatial structures of cone penetration test parameters in a liquefaction site in taiwan are estimated based on multiple cpts conducted in situ the study area was divided into three sub regions based on the geological condition of the study area the results show that in the vertical profile cone tip resistance q c has a larger scale of fluctuation sof than that of sleeve friction f s the soil profile which is composed of various sources and complex process of deposition has a smaller sof in q c parameter however the spatial structure in f s parameter is not sensitive to the geological formation the analysis results of the cpt data in horizontal direction indicate that the correlation distances of q c and f s in horizontal direction are similar the horizontal spatial structure is dominated by the anisotropy of the geological and river systems in conclusion this study demonstrates that a proper geological zonation is necessary for estimating the spatial structure in both the vertical and horizontal directions

hydraulic properties of 3d rough walled fractures during shearing an experimental study abstract this study experimentally analyzed the influence of shear processes on nonlinear flow behavior through 3d rough walled rock fractures a high precision apparatus was developed to perform stress dependent fluid flow tests of fractured rocks then water flow tests on rough walled fractures with different mechanical displacements were conducted at each shear level the hydraulic pressure ranged from 0 to 0 6 mpa and the normal load varied from 7 to 35 kn the results show that i the relationship between the volumetric flow rate and hydraulic gradient of rough walled fractures can be well fit using forchheimer s law notably both the linear and nonlinear coefficients in forchheimer s law decrease during shearing ii a sixth order polynomial function is used to evaluate the transmissivity based on the reynolds number of fractures during shearing the transmissivity exhibits a decreasing trend as the reynolds number increases and an increasing trend as the shear displacement increases iii the critical hydraulic gradient critical reynolds number and equivalent hydraulic aperture of the rock fractures all increase as the shear displacement increases when the shear displacement varies from 0 to 15 mm the critical hydraulic gradient ranges from 0 3 to 2 2 for a normal load of 7 kn and increases to 1 8 8 6 for a normal load of 35 kn and iv the forchheimer law results are evaluated by plotting the normalized transmissivity of the fractures during shearing against the reynolds number an increase in the normal load shifts the fitted curves downward additionally the forchheimer coefficient decreases with the shear displacement but increases with the applied normal load

electrical resistivity tomography to understand clay behavior during seasonal water content variations abstract problems with foundations highlight a lack of understanding surrounding factors which influence ground movements during wet dry cycles vincent 2009 to address this issue geotechnical characterizations of a clayey formation can be used to identify significant variability in lithological facies both vertically and horizontally over very short distances soil heterogeneities explain in this case a wide range of geotechnical parameters and weak correlations between them assessed on soil behavior observed on site this paper focuses on soil water deficits and benefits over time related to soil composition in a heterogeneous clay formation through the use of electrical resistivity tomography ert electrical resistivity tomography and time domain reflectometry tdr were used simultaneously to measure resistivity and soil moisture at an experimental field site with the unique objective of qualifying soil moisture in this first stage of the study the resistivity variations obtained from ert were compared to local effective rainfall and soil moisture measurements from time domain reflectometry tdr down to a depth of 3 m results show the potential of qualifying soil water content variations over the seasons and especially of detecting a rapid increase in humidity thanks to spatial soil heterogeneity at a decimetric scale ert proves to be a useful method of delineating soil facies based on their drying and humidification behavior

indirect determination of the modulus of deformation of rock masses based on the gsi system today as a result of the increase in the number of large tunnel constructions and underground excavations required for civil engineering and waste disposal and the operation of deep open pit mines determination of rock mass properties has become one of the most important stages in design and construction for rock engineering when rocks and rock masses are classified for geotechnical purposes this needs to be on the basis of strength or static modulus of deformation to give an indication of their stability or deformational response in addition the strength and modulus of deformation are the necessary input parameters of the rock masses to be utilized by numerical methods the modulus of elasticity of the rock material is undoubtly the geomechanical parameter that best represents the mechanical behaviour of rock material a similar conclusion can also be made for rock masses however the modulus of deformation of rock masses should be determined in situ by carrying out special tests which normally implies considerable costs and operational difficulties because of such difficulties the determination of the modulus of deformation of the rock masses continues to attract the attention of rock engineers and engineering geologists given the importance of having the value of the modulus of deformation available and at the same time the operational and economical difficulties mentioned above many researchers mentioned below were led to consider several cost effective and not too time consuming indirect procedures that can provide information on the modulus of deformation these attempts

effects of longitudinal variability of soil on a continuous spread footing abstract a simple model describing the soil foundation interaction for continuous wall footing and which takes longitudinal variations in soil s properties into account is presented in this paper this model has been developed using a finite element representation in which a 1d structure continuous spread footing rests on a spatially variable soil described by winkler type springs characterized by the subgrade reaction coefficient geotechnical pressuremeter tests and geophysical vlf r very low frequency resistivity mode surveys performed over a selected study area resting on an alluvial terrace were used to provide information on the soil s variability and to reveal the presence of clayey soil three kinds of natural variability are considered natural soil variations rapid variations in the soil s properties and shrinkage of clayey soil a relationship between the coefficient of subgrade reaction and the resistivity was observed the spatial variability of the coefficient of subgrade reaction was analyzed using geostatistics and then used in the model to derive differential settlements and bending moment values of a continuous spread footing which cannot be predicted if the soil is assumed to be homogeneous or if shrinkage under the continuous wall footing is not taken into account results show that as is often the case in practice when the longitudinal soil variability is not taken into account the design may be unsafe

3d geostatistical modeling of lascaux hill from ert data abstract the lascaux cave located in southwest france is one of the most important prehistoric caves in the world that show paleolithic paintings this study aims to simulate the 3d geological environment of the cave by geostatistical modeling based on 2d electrical resistivity tomography ert data seventeen ert profiles were carried out resulting in 64 195 geolocated resistivity values covering about 14 500 m2 of the lascaux site from this dataset 3d resistivity geo model has been built by geostatistical method we used geotechnical data from 36 boreholes and cone penetrometer tests to validate the geo model by modeling from 2d data we can establish a good estimation of the 3d geological environment of the lascaux site our results show that the site can be generally separated in two parts the limestone promontory in the center and the detrital formations located in both east and west sides there is a high contrast between resistivity of the two formations 45 m detrital formation to 556 m limestone with a rough boundary in the center the limestone could also be separate into two parts a superficial layer of weathered limestone 150 m and a deeper layer with compact limestone 556 m

reliability based design for allowable bearing capacity of footings on rock masses by considering angle of distortion abstract this study addresses the impact of spatial variability on the angle of distortion between two footings in rock masses a simple elasto perfectly plastic model based on the hoek brown criterion is taken to simulate the spatial variation of rock mass properties in the finite element analyses this model is calibrated by a large rock mass database with monte carlo simulations stochastic samples of angle of distortion between two footings are obtained which are further used to derive reliability based allowable bearing stresses the analysis results show that the geological strength index gsi of rock masses and uniaxial compressive strength of intact rock are the two dominate factors that affect the reliability based design comparisons to the existing codes show that these codes are appropriate for poor to fair rock masses conservative for good to very good rock masses and un conservative for very poor rock masses

simulation of three dimensional flow of immiscible fluids within and below the unsaturated zone this paper presents a two phase flow model based on a three dimensional finite difference formulation as three dimensional simulations can require substantial computer effort a numerical technique that takes advantage of vector and parallel processing computer architecture is developed the model is posed in terms of water saturation and nonwetting fluid pressure it uses three phase capillary pressure and relative permeability relationships to permit simulation within or below the unsaturated zone a modified formulation of slice successive overtaxation an iterative matrix solution technique is introduced this technique is designed to use parallel processing capabilities of new computers the model is applied to immiscible fluid flow at two chemical waste landfills near niagara falls new york at both sites denser than water nonaqueous liquids napls are present in the groundwater regimes in relatively large quantities the model applications address several technical concerns at the two sites including the effectiveness of clay as a geologic barrier to napl migration owing to capillary pressure forces the three dimensional aspects of dense napl flow and the sensitivity of napl recovery in pumping wells due to various hydrogeologic and fluid properties the results of the applications show that 1 even under a downward hydraulic gradient natural differences in capillary pressure relationships for different lithologies can prevent downward migration of napl 2 without any lithologic capillary barrier an upward hydraulic gradient induced by a de watering system can prevent downward migration of napl 3 napl recovery at wells is sensitive to relative permeability a relationship that requires field calibration in many settings and 4 the three dimensional aspects of two phase flow and hydrogeologic heterogeneity require explicit treatment in many settings

the boolean stochastic generation method bosg a tool for the analysis of the error associated with the simplification of the stratigraphy in geotechnical models abstract in geotechnical modelling some minor stratigraphic features are usually discarded in order to simplify the problem avoiding to deal with further uncertainties about their position thickness and lateral extent the study proposes a new method based on the stochastic generation of different soil layers configurations following a boolean logic the material is either matrix or layer i e gravel lenses in a clay rich matrix the method has been called bosg boolean stochastic generation the methodology allows to randomize the presence of a specific material interdigitated in a uniform matrix thus enabling to gather a dataset which could be analysed automatically in order quantify the error associated with the adopted simplification the commercial codes flac and flac3d were used for the geotechnical modelling a specifically coded matlab program allows to generate randomly the different soil configurations and then to automate the computation with the commercial software in order to maximize the sample number in this paper the methodology is applied with reference to a simplified slope in 2d and in 3d results show that within a low resistance matrix the presence of layers with higher friction angle can significantly affect significantly the stability and the displacement pattern of an unstable slope therefore a method to investigate the influence of the spatial distribution of these layers can be particularly useful

hydromechanical properties and alteration of natural fracture surfaces in the soultz granite bas rhin france natural fractures are characterized by rough surfaces and complex fluid flows a large distribution of apertures residual voids within their walls and the presence of contact points in situ normal loads produce heterogeneous flows channeling the resulting permeabilities porosities or fluid rock exchange surfaces cannot be realistically modeled by parallel and smooth plate models four natural fractures are sampled at different depths and degrees of alteration in the soultz sandstone and granite eps1 drillhole soultz sous forets bas rhin france the fracture surfaces are measured with mechanical profilometry and maps of asperity heights xyz resulting local apertures xye are then calculated a statistical study of the surface profiles xz show that the fractures are more or less rough and tortuous according to the types of alteration altered samples are characterized by smoother surfaces of fractures such differences imply that i the average fracture aperture is not representative for the whole fracture and that ii the different local apertures should be integrated in hydraulic and mechanical models a hydraulic model finite difference calculations of fluid flow taking into account the elastic closure hertz contact theory of fractures with depth is used maps of contact points and relative local loads within the fracture planes are compared to flow maps they show different channeling of fluid flows strongly altered fractures are characterized by homogeneous fluxes despite the presence of numerous contact zones during the closure of fracture by contrast fresh fractures develop increasing fluid flow channels with depth fracture closure increasing normal stress does not systematically increase the channeling of fluid flow there is evidence for a general smoothing out of the irregularities of the fracture walls due to precipitation of secondary minerals indicating that the cubic law can be commonly valid also at great crustal depth but this validity depends on the degree of fracture alteration mineralogical and geochemical observations thus should be taken into account to perform more accurate permeability calculations and models of fluid circulation in fracture networks d 2002 elsevier science b v all rights reserved

hydrogeotechnical characterization of a metallurgical waste this paper presents the results of hydrogeotechnical characterization tests carried out on the metallurgical waste mw from a tailings impoundment located on the terraces of the moa river cuba characterization of the mw includes chemical and mineralogical analysis oedometer tests triaxial tests tensile strength tests determination of the water retention curve and shrinkage and permeability tests the mw which has a grain size distribution similar to that of a silt mainly contains iron and heavy metals minerals and has low plasticity consolidated undrained triaxial tests on remoulded samples indicate a dilative behaviour with a decrease in pore water pressure near failure the material is susceptible to liquefaction when subjected to a cyclic load in the triaxial test hydraulic conductivity soil stiffness and compressive and tensile strength of the mw have an important dependence on the degree of saturation and vary significantly during the drying process the results indicate that during t

subsurface water flow simulated for hillslopes with spatially dependent soil hydraulic characteristics water flow through hillslopes consisting of five soil layers with varying spatial dependence in hydraulic characteristics in the lateral plane was simulated by solving richards equation in three dimensions under varying rainfall intensities and for two complexities of terrain by concepts of similar media the variability in soil hydraulic characteristics was expressed by a single dimensionless parameter the scaling factor the moments of log normally distributed were set as mean 1 0 and standard deviation 1 0 four cases of spatial dependence of in the lateral plane were selected for simulation using exponential variogram functions ranging in spatial structure from radom no spatial dependence to large dependence large correlation lengths the simulations showed that the rates of subsurface flow from the 30 hillslope during and following rainfall were significantly enhanced with an increase in spatial dependence subsurface drainage was also increased with increases in rainfall intensity and slope complexity for hillslopes the relative effect of spatial dependence in soil hydraulic characteristics was smaller with 30 horizontal pitching than without pitching hillslopes with a random distribution of hydraulic characteristics provided greater opportunity for soil units with differing water capacities to interact than in cases with spatially correlated distributions this greater interaction is associated with a greater lag in subsurface flow generation these studies illustrate some of the expected effects of spatial dependence of soil hydraulic characteristics on the integrated hydrologic response of land areas

mapping groundwater contamination using dc resistivity and vlf geophysical methods a case study geophysical methods can be helpful in mapping areas of contaminated soil and groundwater electrical resistivity and very low frequency electromagnetic induction vlf surveys were carried out at a site of shallow hydrocarbon contamination in utah county utah previously installed monitoring wells facilitated analysis of water chemistry to enhance interpretation of the geophysical data the electrical resistivity and vlf data correlate well and vertical cross sections and contour maps generated from these data helped map the contaminant plume which was delineated as an area of high interpreted resistivities

a probabilistic approach to soil layer and bedrock level modeling for risk assessment of groundwater drawdown induced land subsidence sub surface construction in urban areas generally involves drainage of groundwater which can induce subsidence in soil deposits knowledge of where compressible sediments are located and how thick these are is essential for estimating subsidence risk a probabilistic method for coupled bedrock level and soil layer modeling to detect compressible sediments is presented the method is applied in an area in central stockholm where clay is the compressible sediment layer first a bedrock level model was constructed from three sources of information a geotechnical drillings reaching the bedrock b drillings not reaching the bedrock and c mapped bedrock outcrops input data for the probabilistic bedrock level model was generated by a stepwise kriging procedure second a three layer soil model was constructed including the following materials a coarse grained post glacial and filling material below the ground surface b glacial and post glacial clays and c coarse grained glaciofluvial and glacial till deposits above the bedrock layer thicknesses were transformed to proportions of the total soil thickness since kriging requires data to be normally distributed the proportions were transformed from proportions p to standard normal quantiles z in each iteration of a monte carlo simulation a spatial distribution of the bedrock level was simulated together with the transformed values for the soil layer proportions from the iterations the probability density of the clay thickness compressible sediments at each grid cell was calculated the results of the case study map the expected value mean and the 95th percentile of the probability of compressible sediments at specific locations the resulting model is geologically realistic and validated through a cross validation procedure in order to be in good agreement with a reference dataset the case study showed that the method can efficiently handle large amounts of data and requires little manual adjustment moreover the mapped results can provide useful decision support when planning risk reducing measures and when communicating with stakeholders although this novel method is developed for risk assessment of groundwater drawdown induced subsidence it is useful for other applications involving spatial soil strata modeling

numerical modeling of the groundwater flow system of the gumera sub basin in lake tana basin ethiopia the groundwater flow contribution into lake tana was simulated using gumera river sub basin as a case study draining into lake tana the gumera sub basin boundary was delineated from a 90 m shuttle radar terrain mapping srtm digital elevation model dem using archydro tools the sub basin boundary served as the divide line of the groundwater flow while stream networks were used as internal drainage lines input parameters such as transmissivity and hydraulic conductivity were obtained from past studies and experts knowledge based on the geological information of the sub basin unconfined subsurface flow condition was considered and simulated using modular 3d finite difference ground water flow model modflow analytical solutions were also used for comparison purposes the result indicates that head contours are aligned to the streams showing their relationship as a subdued form of the surface water flow which are dictated by the morphology of the basin this suggested the need to account groundwater contribution of the sub basins to lake tana as baseflow and to estimate groundwater inflow from the floodplain separately the contribution from the floodplain was estimated using a finite differences method which showed an inflow of 0 15 billion cubic meter bcm from rivers into the floodplain out of which 0 09 bcm is flowing out to the lake tana and 0 06 bcm stored in the aquifers of the floodplain the stored quantity could meet irrigation demands as well as contribute to the preservation of the ecological structure and function of the area the study suggests further research on validation of parameters through inverse modeling approaches and optimization of water allocations

combining borehole log stratigraphies and ambient vibration data to build a 3d model of the lower var valley nice france abstract in seismic hazard studies site effects assessment is based on an accurate knowledge of mechanical properties and geometry of superficial geological formations the lower var valley nice southeastern france is a 2 km wide fluvial sedimentary basin where site effects have been observed on earthquake recordings in addition this area is a significant economically developing zone including the second largest airport of france therefore it is highly important to define a 3d sub surface model of the basin to understand the ground motion amplifications based on the compilation of several years of geotechnical and geophysical studies the quaternary alluvial deposits of the lower var valley were investigated using 331 borehole log stratigraphies and 439 ambient vibration measurements these data were combined in a commercial software that models and allows to visualize geoscientific data and geological models in 3d the borehole log stratigraphies helped to define a representative lithostratigraphic soil profile and the geometry of the different sedimentary layers only few boreholes are reaching the engineering bedrock pliocene conglomerates characterized by a s wave velocity larger than 800 m s 1 from the ambient vibration data the fundamental resonance frequency identified from h v curves indicates the bedrock depth using the well known f0 vs 4h relationship these h v curves were interpreted using geological knowledge of the studied zone our results show that the bedrock depth varies in the center of the valley between 50 m in the northern part of the studied zone and more than 100 m on the river estuary first the average s wave velocity in the alluvial deposits is estimated according to combined analysis of the borehole log stratigraphies and h v calculations on ambient vibration measurements the spatial variability of this velocity has been translated into a velocity zonation of the valley second this zonation allows us to extrapolate the quaternary pliocene limit in the whole valley the 3d model of the lower var valley will be useful in future numerical simulations of seismic ground motions in order to evaluate and mitigate seismic risk in the area

effective hydraulic conductivities of transient unsaturated flow in stratified soils the effective hydraulic conductivities of transient unsaturated flow in stratified soils are evaluated using a three dimensional stochastic approach because of the disparity of the correlation scales in a stratified soil the general stochastic equations are simplified and this allows analytical evaluation and derivation of generic expressions for the effective hydraulic conductivities simple asymptotic expressions valid at particular ranges of the soil property and the mean flow characteristics are also derived several examples illustrating the results using data from two real soils are also presented it was found that the effective hydraulic conductivities show significant hysteresis and are anisotropic with a degree of anisotropy depending on the mean flow conditions wetting or drying such hysteresis and anisotropy are produced by the spatial variability of the hydraulic soil properties rather than hysteresis or anisotropy of the local parameters a physical interpretation of the results is given along with a qualitative comparison with field observations the ramifications of this study need to be further investigated and be considered in field applications such as waste disposal control

origin age and movement of pore water in argillaceous quaternary deposits at four sites in southwestern ontario hydrogeologic information in the form of textural properties field and laboratory determined hydraulic conductivity values vertical hydraulic gradients from piezometer nests and major ion and isotopic contents 18o 2h 3h 13c 14c was obtained from four sites located in southwestern ontario on thick deposits of clayey till and glaciolacustrine clay at each site the piezometers were installed from the water table zone situated 1 4 m below the surface to a maximum depth between 20 and 35 m below the surface values of hydraulic conductivity determined in the laboratory by consolidometer and triaxial methods are in the order of 10 8 10 7 cm s and are similar to values calculated from rates of water level rise in piezometers mean values of average vertical groundwater velocity calculated with the measured values of hydraulic conductivity porosity and hydraulic gradient using the darcy equation for a saturated non fractured porous medium range from 0 13 to 0 26 cm yr tritiated pore waters only occur within 3 6 m of ground surface thereby indicating that groundwaters below this depth recharged prior to at least 1952 18o in the pore waters exhibit a distinctive regular shift with depth from water table values of 9 to 10 smow characteristic of present day precipitation to values between 14 and 17 at depths of 20 40 m which are characteristic of much cooler waters corrected 14c ages of the groundwater are greater than 8000 yr b p thereby suggesting that the groundwaters at depth entered these deposits during or after the formation of these deposits approximately 11 000 to 14 000 yr ago 18o 2h and cl concentration profiles were simulated with a one dimensional model for transport by advection and diffusion in a saturated porous medium reasonable agreement between the model and the field profiles was obtained with values of effective diffusion coefficients of 3 0 10 6 cm2 s for 18o 2h and cl and with groundwater velocities between 0 03 to 0 05 cm yr based on these results it is concluded that the pore water in these deposits is a mixture of late pleistocene and modern waters and that the distribution of 18c 2h and cl in these deposits is influenced predominantly by molecular diffusion apparently more so than by hydraulic flow

influence of soil heterogeneity on load redistribution and settlement of a hyperstatic three support frame spatial and geometrical variability of mechanical soil properties can induce differential settlements and load redistribution in hyperstatic structures therefore damage prevention requires specific attention to be paid to the global mechanisms of soil structure interaction a reduced scale model of a hyperstatic three support frame scale 1 100 is installed on the cea cesta centrifuge up to 100g various configurations are studied with different loadings different structural stiffnesses and different geometries of the soil layer strain gauges are fixed at various points so as to enable the retro analysis of all components of forces at free ends displacements are recorded at several points on the structure and on the free surface a numerical model of the frame based on beam theory with elastic supports is calibrated first to determine an equivalent support stiffness and second to quantify the effect of variations of the structural stiffness soil modulus ratio on the structural response a prob

groundwater geochemistry and composition of hardpans in southwestern australian regolith the mineralogy and geochemistry of pedogenic and groundwater silcretes and ferricretes and associated groundwater geochemistry were investigated for deeply weathered highly kaolinised lateritic regolith in southwesternaustralia the silcretes and ferricretes form subsurface hardpans and impede movement of the highly saline acidic shallow groundwaters in lower valleys of the subdued ancient landscape these valleys are associated with the discharge of groundwater and the formation of saline seeps which host a variety of secondary minerals including amorphous silica opal ct goethite feooh hematite fe 2 o 3 akaganeite feooh jarosite kfe 3 so 4 2 oh 6 barite baso 4 gypsum caso 4 2h 2 o and halite nacl deep groundwater silcretes are commonly composed of silicified in situ lateritic pallid zone materials and saprolite that have developed from granitic rocks the matrix consists of amorphous silica diffused through a porous kaolin groundmass these materials were initially highly porous but the voids are now mostly occupied by amorphous silica and secondary anatase acid groundwater weathering has resulted in the dissolution of most primary silicates including feldspars and micas which has greatly elevated the concentration of dissolved silicon in groundwater isovolumetric weathering of feldspar initially produced highly porous assemblages of fine grained kaolin and minor halloysite which now contain high concentrations of amorphous silica up to about 50 wt occupying most of the pores alkali feldspars alter to kaolin pseudomorphs that are much more porous than vermicular kaolin pseudomorphs replacing mica minerals consequently these pseudomorphs contain much less amorphous silica geochemical modeling using phreeqc enabled prediction of the saturation state of minerals and indicated the dissolution and precipitation reactions occurring in the regolith groundwater environment acid moderately saline groundwaters were in near equilibrium with respect to amorphous silica while near neutral ph saline groundwaters corresponded to undersaturated conditions for extremely acid groundwaters ph 3 5 phreeqc predicted dissolution of kaolin goethite and hematite which is reflected in the elevated concentrations of iron up to 169 mg l and aluminium up to 389 mg l in the groundwater this study is important for the understanding of how groundwater geochemistry influences the precipitation of cementing minerals that form various hardpans in the southwest australian landscape

tracer test to assess flow and transport parameters of an earth slide the montecagno landslide case study italy abstract subsurface water processes are principle triggering and driving factors during slope movements however the hydraulic properties that drive groundwater flow along the slope remain poorly understood moreover landslide deposits are often characterized by layering and fissures that cause high heterogeneity in the distribution of hydraulic properties this heterogeneity leads to great uncertainty in the prediction of groundwater flow paths this study aimed to improve understanding of hydraulic and transport properties of deep earth slides and to identify preferential flow directions inside the landslide body a dye tracer test was used to estimate transport parameters and characterize groundwater flow paths the results indicate that in the studied landslide two groundwater flow types exist and are related to the presence of fissured rock blocks and debris horizons embedded in a fine matrix the estimated low groundwater flow velocity has rarely been estimated in other studies of this landslide type the groundwater flow direction appears to be mainly influenced by the failure surface shape and differs from the sliding direction our results differ from those in other landslide studies and improve our knowledge of groundwater flow properties in deep earth slides furthermore they offer a new contribution to slope stability analyses and formula and to the effective design of mitigation strategies

geostatistical method for analysing soil displacement from underground urban construction the aim of this study was to assess the influence of uncertainties related to soil variability in the numerical modelling of settlements caused by underground work based on a large number of in situ tests a geostatistical method kriging applied to the stratigraphy of the sub surface was justified and used in order to determine the mean position of the soil layers and their estimation variances in a first stage the influence of the uncertainty in the soil stratigraphy on the calculated surface settlements was analysed in a second stage a stochastic finite element method was used to introduce the influence of uncertainty in the soil mechanical parameters on the predicted surface settlements

modelling of groundwater flow in heterogeneous porous media by finite element method the hysuf fem code hydrodynamic of subsurface flow by finite element method is proposed in this article in order to estimate the spatial variability of the transmissivity values of the berrechid aquifer morocco the calibration of the model is based on the hydraulic head hydraulic conductivity and recharge three numerical tests are used to validate the model and verify its convergence the first test case consists in using the steady analytical solution of the poisson equation in the second the model has been compared with the hydrogeological system which is characterized by an unconfined monolayer isotropic layer and computed by using pmwin modflow software the third test case is based on the comparison between the results of hysuf fem and the multiple cell balance method in the aquifer system with natural boundaries case good agreement between the hydrodynamic of subsurface flow the numerical tests and the spatial distribution of the thickening of the hydrogeological system is deduced from the analysis and the interpretations of hydrogeological wells copyright 2011 john wiley sons ltd

study of nonuniform bedding support because of erosion under cast iron water distribution pipes abstractseveral recent studies have investigated failure mechanisms for cast iron water pipes these studies have primarily focused on the adverse effects of corrosion frost reactive backfill and earthquakes it appears that leaking pressure pipes can produce erosion voids under the buried structure in this paper a parametric study employing three dimensional finite element analyses is used to examine buried continuous cast iron water pipes the objective is to understand the effect of such erosion voids on the stability of buried cast iron pipes and the longitudinal soil pipe interaction the results of the finite element analyses demonstrate that the radial r and the axial stresses a are low compared with the hoop stresses and the peak tension is always in the hoop direction as a result of the high hoop stresses induced by the nonuniform bedding support longitudinal fractures are likely to occur in the pipe which may consequently cause pipe failure

high sampling rate measurement and data treatment for mobile investigations kinematic electrical resistivity tomography kert abstract this paper presents an innovative system which adapts electrical resistivity tomography ert for fast investigation on long transects the device consists in a set of on the go sensors allowing high sampling rate measurement for mobile prospections the weak contact between the mobile sensors and the soil to allow fast investigations induces very noisy raw datasets kinematic electrical resistivity tomography named kert is then associated with a data treatment process a two step process reveals the information contained in the datasets the first focuses on the procedure to remove noise through the use of a low pass filter the assessment of cutoff frequency for smoothing is deduced from a fast fourier transform fft analysis thus the value is adapted to the site and the prospection the second phase consists in calibration of the kert on a conventional static ert at this point a classical static ert was used as a reference and directed on a reduced part of the kert transect the estimation of a factor of calibration xc to correct bias revealed the resistivity variations along the entire transect and in depth in the last part of the paper the validation of the investigation method and data treatment methodology is performed on a real case study a 450 m transect is investigated in 5 min mean speed about 6 km h integrating 10 depths of investigation the steps of data processing are detailed to show the final results consisting in a zonation along the transect

stochastic analysis of unsaturated flow in heterogeneous soils 3 observations and applications results of stochastic theory for flow in heterogeneous soils are analyzed by comparisons with laboratory experiments and field observations and through applications examples the two key theoretical results are 1 the variability of capillary pressure or moisture content increases when mean capillary pressure increases and 2 the anisotropy ratio horizontal vertical of effective mean unsaturated hydraulic conductivity increases when mean capillary pressure increases or mean moisture content decreases comparisons with the field data on moisture content and capillary pressure variability show trends similar to those predicted by the theory calculations of hydraulic conductivity anisotropy based on two actual soils show that the variations in soil texture produce large changes in anisotropy as the mean capillary pressure changes several previously reported field observations and laboratory experiments support the theoretical finding of a capillary pressure dependent hydraulic anisotropy for unsaturated flow the importance of this anisotropy effect in applications involving groundwater recharge irrigation surface runoff generation and waste isolation is discussed

reconstructing hydraulic conductivity field for hydrogeological modeling in an urban environment abstract hydrogeological analysis of flow is largely based on the concept of hydraulic conductivity in numerical hydrogeological modeling a value of hydraulic conductivity must be assigned at each element of mesh in heterogeneous geological formations this value governs the average behavior of groundwater flow within an aquifer the goals of this study are twofold 1 development of a methodology to transform the description of lithological units into local hydraulic conductivity values and 2 development of a methodology for reconstruction of hydraulic conductivity fields on a 83 km2 of the bordeaux urban area two approaches a 2d approach and a 3d approach based on geostatistical analysis are explained in details and compared for both approaches variographical analysis and ordinary kriging are carried out on the logarithmic of hydraulic conductivity and composite hydraulic conductivity is calculated using thickness weighting to get horizontal and vertical hydraulic conductivities the comparison of both approaches and the assessment of their potential and limitations suggest that the 2d approach is more appropriate than the 3d approach

spatially varying hydraulic and solute transport characteristics of a fractured till determined by field tracer tests funen denmark a natural gradient tracer test that simulated one dimensional flow was conducted in a large 4 m 4 8 m surface area isolated block of fractured till in funen denmark to determine both bulk and spatially distributed hydraulic properties hydraulic conductivity based on free flow tests was higher in the upper 2 5 m 5 81 10 5 m s 1 than in the upper 4 m 8 00 10 6 m s 1 of till indicating the more highly fractured and bioturbated nature of the upper part of the till chloride was introduced at the surface of the block as nacl solution 490 mg l 1 cl and breakthrough of cl was monitored in 13 horizontal screens at depths of 2 5 and 4 m arrival times of half of the input cl concentrations c c0 0 5 ranged about sevenfold among various screens at each sampling depth 5 35 hours at 2 5 m and 11 68 hours at 4 m chloride breakthrough data for the two depths were fitted to both an equivalent porous media epm model based on the convective dispersive equation and a discrete fracture model these results indicate differences in transport characteristics of the till with depth at the 2 5 m depth the epm model fit the initial part of the breakthrough curves quite well for most samplers but did not predict the long tails adequately the converse was generally true for the discrete fracture model thus it appears that transport in the upper 2 5 m of till is controlled by a complex interconnected system of fractures and macropores field measurements of fractures and macropores at this site substantiate these results at the 4 m depth the discrete fracture model described solute transport in all samplers better than the epm model indicating that vertical fracture flow dominates in the lower portion of the block fracture apertures and spacings were estimated based on the cubic law and fitting the breakthrough data to the discrete fracture model fitted fracture spacings at the 4 m depth 0 025 0 08 m were slightly smaller than the minimum spacing 0 09 m mapped in the field calculated apertures at the 4 m depth were large compared with other studies and ranged from 65 to 127 m average value of 94 m

unified pipe network method for simulation of water flow in fractured porous rock abstract rock masses are often conceptualized as dual permeability media containing fractures or fracture networks with high permeability and porous matrix that is less permeable in order to overcome the difficulties in simulating fluid flow in a highly discontinuous dual permeability medium an effective unified pipe network method is developed which discretizes the dual permeability rock mass into a virtual pipe network system it includes fracture pipe networks and matrix pipe networks they are constructed separately based on equivalent flow models in a representative area or volume by taking the advantage of the orthogonality of the mesh partition numerical examples of fluid flow in 2 d and 3 d domain including porous media and fractured porous media are presented to demonstrate the accuracy robustness and effectiveness of the proposed unified pipe network method results show that the developed method has good performance even with highly distorted mesh water recharge into the fractured rock mass with complex fracture network is studied it has been found in this case that the effect of aperture change on the water recharge rate is more significant in the early stage compared to the fracture density change

coupled hydromechanical modeling of rock fractures under normal stress in this paper a nonlinear poromechanical model is developed for a single rock fracture under normal stress the fracture is represented by a set of voids and the progressive fracture displacement

in situ study of the shrinkage swelling of a clay soil over several cycles of drought rewetting abstract this article presents results describing the in situ behavior of clay soils pleistocene brach formation regarding shrinkage and swelling an experimental site was established different types of sensors were used to continuously measure the movements of the clay bed rock and variations in the temperature and water content of the soil these parameters were correlated with annual climatic variations as measured at an on site meteorological station the results obtained thus far represent five cycles of drought rewetting thus enabling a medium term study of the shrinkage swelling of a clay soil over time a cumulative effect of shrinkage over several cycles was observed with non negligible variations of water content to a depth of 3 m almost 1 cm of cumulative shrinkage occurred over the first three cycles of a 2 meter thick clay layer the last two cycles were marked by a stabilization of the swelling by determining the accumulated soil hydric condition over time we discovered a correlation between this parameter and the periods of shrinkage swelling the accumulated hydric condition as defined in this article is a good indicator of the behavior of soil under shrinkage and swelling

unsaturated flow in spatially variable fields 1 derivation of models of infiltration and redistribution models of water flow in the upper soil layer of spatially variable fields are developed field variability is assumed to take place in the horizontal plane the saturated hydraulic conductivity is assumed to be a random variable of lognormal distribution and head suction and moisture content are related to it by simple analytical relationships the aim of the study is to derive the expectation and variances of the moisture content suction heads hydraulic conductivity and water flux as functions of depth and time for infiltration and redistribution toward this aim a simplified solution of vertical flow in a homogeneous column based on the concept of moving front is developed the statistical procedure for using this solution in a spatially variable field is outlined

empirical estimation of rock mass modulus the deformation modulus of a rock mass is an important input parameter in any analysis of rock mass behaviour that includes deformations field tests to determine this parameter directly are time consuming expensive and the reliability of the results of these tests is sometimes questionable consequently several authors have proposed empirical relationships for estimating the value of rock mass deformation modulus on the basis of classification schemes these relationships are reviewed and their limitations are discussed based on data from a large number of in situ measurements from china and taiwan a new relationship based upon a sigmoid function is proposed the properties of the intact rock as well as the effects of disturbance due to blast damage and or stress relaxation are also included in this new relationship