A model for multiphase flow and transport in porous media including a phenomenological approach to account for deformation—a model concept and its validation within a code intercomparison study

Multiphase flow processes in unsaturated cohesive soils are often affected by deformation due to swelling and shrinking as a result of varying water contents. This paper presents a model concept which is denoted ‘phenomenological’ in terms of the processes responsible for soil deformation, since the effects of deformation on flow and transport are only considered by constitutive relations that allow an adaptation of the hydraulic properties. This new model is validated in a detailed intercomparison study with two state-of-the-art models that are capable of explicitly describing the processes relevant for the deformation. A ‘numerical experiment’ with a state-of-the-art reference model is used to produce ‘measurement data’ for an inverse-modelling-based estimation of the model input parameters for the phenomenological concept.     

Soil–structure cyclic direct shear tests: a new interpretation of the direct shear experiment and its application to a series of cyclic tests

This paper presents a series of cyclic 2D direct shear tests on sand–rough material interfaces under constant normal load (CNL) and constant normal stiffness (CNS) conditions. The aim of these tests is to describe the behavior of the soil–pile contact subjected to a large number of cycles due to environmental or anthropic loadings. These cycles (typically 10⁴ or less due to an early rupture) are small (10, 20 and 40 kPa in terms of shear stress). A new interpretation of the direct shear tests is proposed. The sample of soil is schematically composed of a sheared interface and of a buffer under oedometric load. The problem of sand leakage between the shear box and the rough plate, classical phenomenon in this type of test, is focused. The effect of initial density, position of “center of cycles” in stress plane (mean cyclic variables) and cyclic amplitude is investigated. The cycles are defined by the initial mean cyclic normal stress, the level of initial mean cyclic stress ratio and the normalized cyclic amplitude. Under CNL condition, either dilation or contraction is exhibited, in agreement with the characteristic state developed by Luong (International symposium on soils under cyclic and transient loading, Swansea, 7–11 January, pp 315–324, 1980). The influence of a prescribed normal stiffness is especially considered. It can be highlighted that CNS cyclic paths are always contractive. This contraction results in a drop of mean cyclic normal stress often called degradation of friction.     

An example of the use of veins to establish a cover fold history—irregully formation,western Australia

Structural correlation using fold overprinting and style, plus the timing and orientation of possible syntectonic veins, are used to interpret three minor folding events in part of the Irregully Formation. The formation lies near the base of the Middle Proterozoic Bangemall Group in the Bangemall Basin of Western Australia. It comprises interbedded well-laminated dolostones and orthoquartzites, metamorphosed under lower greenschist-facies conditions. Bedding in the formation is folded about a gently NW-plunging axis. Most mesofolds are consistent with the bedding distribution, exhibiting a fold-axis maximum plunging gently NW and vertical axial planes. Folds with NE-, E- and NNE-trending axial planes are common in the area, but most cannot be explained by reorientation of the dominant NW-trending folds.A deformation history accounting for different fold geometries is established using fold overprinting in conjunction with dilational offsets between fold-related quartz and dolomite veins. A number of approaches to determine the history of folding are possible. Fold overprinting is the most valuable criterion, but in weakly deformed terrains it may not be easily recognised, so that alternative methods should be examined. Fold directions in the Irregully Formation are parallel to trends in the underlying Ashburton Formation, suggesting a degree of basement reactivation. As a fold chronology in the cover has been established accounting for mesofolds and macrofolds, the interpreted reactivation is believed to have involved compression rather than passive drape over earlier structures. In the Irregully Formation differently oriented folds probably developed through a degree of cover shortening, associated with reactivation of basement faults or folds.     

Kinematics and significance of a poly-deformed crustal-scale shear zone in central to south-eastern Madagascar: the Itremo–Ikalamavony thrust

International Journal of Earth Sciences - Across the crystalline basement of Madagascar, late Archaean rocks of the Antananarivo Block are tectonically overlain by Proterozoic, predominantly...     

Mathematical and physical modeling to justify a new geophysical method—electrical anisotropy logging

Results of theoretical and experimental studies obtained for an electromagnetic logging probe of new design are presented. As in the case of an induction logging probe, the magnetic dipole of the new probe produces a harmonically varying electromagnetic field, and the parameter to be measured is the electric voltage in the short receiving MN line. The theoretical studies have shown that under certain conditions, the results of measurement with this probe depend on the electrical anisotropy coefficient and do not depend on the longitudinal and transverse electrical resistivities of the anisotropic medium. A technique for determining the electrical anisotropy coefficient was tested on experimental data obtained by physical modeling.     

Constructing a social vulnerability index to earthquake hazards using a hybrid factor analysis and analytic network process (F’ANP) model

Iran is a seismic prone country and has been host to a long series of devastating earthquakes which have resulted in heavy casualties and damages. In order to assess social vulnerability (SV) to earthquake hazards, this paper presents the development of a hybrid factor analysis and analytic network process model for aggregating vulnerability indicators into a composite index of SV to earthquake hazards. The proposed model is then applied in Iran as a case study. The proposed model uses factor analysis (FA) to extract the underlying dimensions of SV. The identified dimensions of SV and their primary variables are then entered into a network model in Analytic Network Process (ANP). The ANP is used to calculate the relative importance of different SV variables, taking into consideration the results obtained from FA and the possible interdependence between variables of the individual dimensions of SV. These weights are then used to compute the factor scores for the individual dimensions of SV and also the composite social vulnerability index (SOVI). The application of the proposed model to a real world case study and its validation show that it is a robust approach for constructing a composite SOVI. Its application to counties in Iran indicates that there exist severe regional differences in terms of SV to earthquake hazards. The pronounced regional variations in SV warrant special attention by both local authorities and the national government to reconsider current natural disaster management strategies.     

Analysis of human risks due to dam-break floods—part 1: a new model based on Bayesian networks

Dam breaks have catastrophic consequences for human lives. This paper presents a new human risk analysis model (HURAM) using Bayesian networks for estimating human risks due to dam-break floods. A Bayesian network is constructed according to a logic structure of loss-of-life mechanisms. The nodes (parameters) and the arcs (inter-relationships) of the network are quantified with historical data, existing models and physical analyses. A dataset of 343 dam-failure cases with records of fatality is compiled for this purpose. Comparison between two existing models and the new model is made to test the new model. Finally, sensitivity analysis is conducted to identify the important parameters that lead to loss of life. The new model is able to take into account a large number of important parameters and their inter-relationships in a systematic structure; include the uncertainties of these parameters and their inter-relationships; incorporate information derived from physical analysis, empirical models and historical data; and update the predictions when information in specific cases is available. The application of this model to the study of human risks in a specific dam-break case is presented in a companion paper.     

Discrete element modelling of a granular platform supported by piles in soft soil – Validation on a small scale model test and comparison to a numerical analysis in a continuum

This paper focuses on the mechanisms taking place in a granular platform supported by piles in soft soil. Several modelling approaches were explored. A two-dimensional small scale model test using the Taylor–Schneebeli soil analogue was first developed and the experimental results were compared to a discrete element model using the particle code PFC. The validation of this numerical approach allowed the parametric study to be extended numerically. Parametric studies were also performed on continuum model using the finite-difference code FLAC. Comparison of the parametric studies performed on each modelling approach underlined some differences and lead to a consideration on the macro- and micromechanical parameters.     

“Calcic amphibole equilibria and a new amphibole-plagioclase geothermometer”—reply to the comment of Poli and Schmidt

Conclusions Although only Al^iv appears in our thermometer expression, this in no way infers that we believe tschermakite (or katophorite, kaersutite and other) substitutions to be unimportant. A careful reading of our earlier papers makes it clear that the reverse is true, e.g. Holland and Richardson 1979; Will et al. 1990a, b; Guiraud et al. 1990. Indeed in B and H (p. 211) we state that natural and synthetic amphiboles are dominated by a combination of edenite, pargasite, hornblende and hastingsite substitutions. What we endeavoured to point out was that because of the nature of reaction (1) and the use of mixing-on-sites activity models the extent of Al substitutions on M2 or Na on M4 do not materially influence our expression for K₁ and consequently our thermometer. Certainly any sophisticated activity model for amphibole explicitly should account for all cross-site interactions between M-, Tl- and A-site cations, as alluded to by P and S in reference to Docka et al. (1987), as well as O3-site anions. However, such a day currently is well away and mixing-on-sites, with modifications as outlined above and to be detailed in T.J.B. Holland and J.D. Blundy (in preparation), seems rather promising for the purposes of amphibole thermometry. We do not share the rather negative and pessimistic outlook on activity models and thermobarometry implicit in P and S comments.     

Numerical analysis on seepage failures of dike due to water level-up and rainfall using a water–soil-coupled smoothed particle hydrodynamics model

For seepage failures of dike due to water level-up and rainfall, surface infiltration and strength change induced by suction reduction are important factors; thus, numerical analysis should consider the coupling of water and soil, as well as the effect of saturation to obtain more precise failure mechanism. Based on the advanced smoothed particle hydrodynamics (SPH) method, this work proposed a two-phase-coupled SPH model in coordination with a novel constitutive model for unsaturated soils. Then, a triaxial compression test is simulated to check the applicability of the SPH method on the soil phase. After that, the failure test of a dike due to water level-up is discretized and simulated, from which the seepage process, the distribution of maximum shear strain, the slip surface, and pore water pressure are obtained. The two-phase-coupled SPH model is also applied to a slope failure test of heavy rainfall, and the results are compared to the model test. Finally, a dike failure test due to rainfall is analyzed using the proposed SPH model to reproduce the surface infiltration and suction reduction. The proposed SPH model provides several insights of seepage failures and can be a helpful tool for the analysis of dike failures induced by water level-up and rainfall.     

Ore mineralization related to geological evolution of the Karkonosze–Izera Massif (the Sudetes,Poland) — Towards a model

The Karkonosze–Izera Massif is a large tectonic unit located in the northern periphery of the Bohemian Massif. It includes the Variscan Karkonosze Granite (about 328–304 Ma) surrounded by the following four older units:

• -Izera–Kowary (the Early Paleozoic continental crust of the Saxothuringian Basin),
• -Ještĕd (the Middle Devonian to Lower Viséan sedimentary succession deposited on the NE passive margin of the Saxothuringian Terrane), out of the present study area,
• -Southern Karkonosze (metamorphosed sediments and volcanics filling the Saxothuringian Basin), out of the present study area,
• -Leszczyniec (Early Ordovician, obducted fragment of Saxothuringian Basin sea floor).

The authors present a genetic model of ore mineralization in the Karkonosze–Izera Massif, in which ore deposits and ore minerals occurrences are related to the successive episodes of the geological history of the Karkonosze–Izera Massif:

• -formation of the Saxothuringian Basin and its passive continental margin (about 500–490 Ma)
• -Variscan thermal events:
  • -regional metamorphism (360–340 Ma)
  • -Karkonosze Granite intrusion (328–304 Ma)
• -Late Cretaceous and Neogene-to-Recent hypergenic processes.

The oldest ore deposits and ore minerals occurrences of the Karkonosze–Izera Massif are represented by pyrite and magnetite deposits hosted in the Leszczyniec Unit as well as by magnetite deposit and, presumably, by a small part of tin mineralization hosted in the Izera–Kowary Unit. All these deposits and occurrences were subjected to the pre-Variscan regional metamorphism.Most of the Karkonosze–Izera Massif ore deposits and occurrences are related to the Karkonosze Granite intrusion. This group includes a spatially diversified assemblage of small ore deposits and ore mineral occurrences of: Fe, Cu, Sn, As, U, Co, Au, Ag, Pb, Ni, Bi, Zn, Sb, Se, S, Th, REE, Mo, W and Hg located within the granite and in granite-related pegmatites, in the close contact aureole of the granite and within the metamorphic envelope, at various distances from the granite. Assuming world standards, all these deposits are now uneconomic. Various age determinations indicated that ore formation connected with the Karkonosze Granite might have taken place mostly between about 326 and 270 Ma.The last ore-forming episode in the Karkonosze–Izera Massif is related to hypergenic processes, particularly important in the northern part of the massif, in the Izera–Kowary Unit where some uranium deposits and occurrences resulted from the infiltration of ore solutions that originated from the weathering of pre-existing accumulations of uranium minerals. A separate problem is the presence of oxidation zones of ore deposits and occurrences, both the fossil and the recent.A full list of ore minerals identified in described deposits and occurrences of the Karkonosze–Izera Massif together with relevant, key references is presented in the form of an appendix.     

Roman Law and political control — from a primitive society to the dawn of the Modern World

The purpose of this paper is to survey the history of Roman Law in order to shed light upon processes whereby society may grow more dynamic. Roman Law is the only one whose development can be traced for over thousand years, a time during which two main epochal crises brought about far-reaching changes to Roman society. The first was a consequence of the second Carthaginian war (218-200 BC), when the raw inhabitants of Latium, in a mere space of sixty years, attained supremacy over the ancient world. The second followed closely upon the death of Emperor Alexander Severus (235 AD), when the growing strength of alien populations was becoming a serious threat to the Empire.These two historical watersheds mark three different ages and three correspondingly quite different law systems that can be named: (i) the Quiritarian or strictly Roman Law, (ii) the Universal-Roman Law, (iii) the Greek-Roman Law. The legal sytem of the first epoch was suitable to a narrow rural society. The law system of the second age was suitable to the ends and values of an open civilised society. The last stage of Roman Law unfolded in the Eastern Empire, and the well-known Code of Emperor Justinian (527–29) marked the climax of this process.As a result of cautious reforms lasting several centuries, the political structures of primitive Roman society(familiae, gentes, tribus) declined, a powerful central authority was built, the nuclear family became the basic building block of society displacing extended family and clan structures, the condition of women was freed from obnoxious tutelage.Traditionally, the Roman estate of thefamilia was nearly a territorial State. Primitive buildings, often mere huts, were independent from each other. The drive to an increasingly civilised urbanisation inevitably brought about a closer spatial integration of the built-up area, and therefore made it necessary the establishment of more and more frequent praedial servitudes. To allow the organisation of urban space to emerge, the builder had to be granted a right to hold the building thus erected, for a limited time or in perpetuity, by lease or sale, against the territorial pretence of extended family or clan authority. Usucaption, pledges, mortgages, initially used in provincial lands, replaced the traditional Roman land transfer procedure(fiducia). In the time of the late Empire, slavery declined and was to some extent replaced by serfdom(colonatus). Roman citizenship was granted to all (212 AD), but the commoners(humiliores) suffered under heavy disabilities. Powerful families(honestiores) often retreated to the countryside, while the rest of the urban population was left to her own devices under an oppressive taxation system. Many luckless heads of families had to become tax proctors: they were held responsible for the gathering of taxes to the extent of their whole estate, and even on pain of torture. The State increasingly took control over most features of social and economic activity, from agriculture to the prices of foodstuffs; while individual enterprise, progress and creativity became more and more stagnant. All these are indicators of an increasingly static society. Oriental despotism became the dominant form of political organisation.Thus, while private law became more and more modernised, paving the way to the present legal systems, the social structure and the spatial organisation became more rigid and less open to innovation. Therefore a very incomplete modernisation occurred. The emergence of more open and dynamic societies was to take place many centuries after the fall of the Western Empire, precisely in the same geographical space that had belonged to it, mainly under the impulse of the more efficient and civilised among the new (Germanic) peoples (Angles, Saxons, Jutes, Franks, Longobards, etc.) who immigrated there with theVölkerwanderung and injected fresh blood into the lands of the former Western Empire, thereby ending oriental despotism. The heritage left by the evolution of Roman Law, however, was to be felt and assimilated by these peoples: it was to become a considerable part of their own cultural and legal heritage, and one of the many factors paving the way to the eventual emergence of dynamic Western societies.The age-long process of change of Roman Law can provide useful glimpses on how attitudes and cultural values not hostile to development may arise and grow to full maturity. Its study can help — though by no means alone — to understand how that part of Europe which came under its direct influence was able to achieve cultural traits open to socio-economic innovations and development.Though each social and spatial system follows its own distinctive path to development (or stagnation), some necessary cultural preconditions are broadly similar for any society. Stress upon individual values is doubtless one such inescapable precondition to the emergence of a dynamic society capable of endogenous development. Unfortunately, utterly opposite values are firmly entrenched in many Third World countries, and social evolution there is, under this viewpoint, exceedingly slow — if any.Centuries had still to elapse for individual values to prevail in Europe after the age of Justinian, and more centuries went by between the triumph of these individual values and the actual take-off stage, which only came about with the industrial revolution. Bearing in mind these facts, the inescapable conclusion arises that the apparent lack of significant cultural change leading towards a dynamic society in many countries must necessarily be a matter of the deepest concern. This is aggravated by other disquieting features of the Third World, such as the propensity to authoritarian regimes — a propensity which in its own turn is closely related to poorly developed individual values.     

Development of a Darcy-Brinkman model to simulate water flow and tracer transport in a heterogeneous karstic aquifer (Val d’Orléans, France)

Darcy’s law is the equation of reference widely used to model aquifer flows. However, its use to model karstic aquifers functioning with large pores is problematic. The physics occurring within the karstic conduits requires the use of a more representative macroscopic equation. A hydrodynamic model is presented which is adapted to the karstic aquifer of the Val d’Orléans (France) using two flow equations: (1) Darcy’s law, used to describe water flow within the massive limestone, and (2) the Brinkman equation, used to model water flow within the conduits. The flow equations coupled with the transport equation allow the prediction of the karst transfer properties. The model was tested by using six dye tracer tests and compared to a model that uses Darcy’s law to describe the flow in karstic conduits. The simulations show that the conduit permeability ranges from 5?×?10^?6 to 5.5?×?10^?5?m² and the limestone permeability ranges from 8?×?10^?11 to 6?×?10^?10?m². The dispersivity coefficient ranges from 23 to 53 m in the conduits and from 1 to 5 m in the limestone. The results of the simulations carried out using Darcy’s law in the conduits show that the dispersion towards the fractures is underestimated.     

How to resolve the controls on mesothermal vein systems in a goldfield characterized by sparse kinematic information and fault reactivation—a structural and graphical approach

Current mine exposures of auriferous veins in the Charters Towers Goldfield (CTGF) are characterized by a scarcity of kinematic indicators. Furthermore, the dip direction of exposed and historically mined orebodies largely coincides with the orientation of pre-existing discontinuities. Consequently, the reactivation of earlier structures during gold deposition is strongly indicated. Both factors complicate the structural analysis of the auriferous vein systems, as slip on earlier faults likely occurred before new rock failure and evolution of fault networks reflecting the stress field present at the time of gold deposition. Despite access to drillcore, open pits and underground workings, extracted data were limited to ten occurrences of wear groove striations and three reverse separations of dykes and a pegmatite cut by sulphide-bearing quartz veins. Because of the scarcity of kinematic information, the structural analysis focused on the geometry of veins and ore-shoots, also applying basic graphical and kinematic methods.     

Using impacts of deep-level mining to research karst hydrology—a Darcy-based approach to predict the future of dried-up dolomitic springs in the Far West Rand goldfield (South Africa). Part 1: a conceptual model of recharge and inter-compartmental flow

Some of the world’s deepest goldmines are located in the Far West Rand (FWR) goldfield operating below of up to 1.2-km-thick dolomites hosting some of the largest karst aquifers in South Africa. Associated impacts include the dewatering of the overlying karst aquifers as well as linking previously disconnected compartments by mining through aquicludes (dykes). The focus of the study is on predicting groundwater balances in re-watered aquifers after mining ceases as this will determine whether or not associated karst springs that dried-up due to dewatering will ever flow again. Critically revisiting, Swart et al. (Environ Geol 44:751–770, 2003a) who predict that all springs will flow again, this study uses significantly larger data sets and modified assumptions to increase the robustness of findings as the question is crucial for post-closure development. As a first of two papers, this part develops a conceptual model on the mega-compartment concept that predicts a flat water table across all linked compartments that would leave the springs dry. The model identifies the ratio between inflowing surface water (recharge) and underground water losses to downstream compartments via mined-through dykes (‘inter-compartmental groundwater flow’, IGF) as a key factor governing the elevation of the post-mining water table, creating the base for part 2, where the IGF and the post-mining water tables are determined using unique large data sets that have not been evaluated before.