Hypoplastic and viscohypoplastic models for soft clays with strength anisotropy

This paper presents a new viscohypoplastic model for soft clays accounting for their typical features—strength anisotropy and rate dependency. The model is based on the hypoplastic model for clays enhanced by the anisotropic shape of the asymptotic state boundary surface. It has been shown that if the surface is skewed, the model predicts different ultimate strength in compression and in extension. Additional enhancement makes the tensor L bilinear in the strain rate, which more realistically predicts the stress paths of K₀ consolidated samples. The new model has been evaluated by simulating laboratory experiments on soft marine clays (Singapore and Bangkok clays). The model can be easily calibrated using only undrained triaxial and odometer tests. The model is subsequently enhanced by the rate effects. The resulting viscohypoplastic model has been evaluated using experiments of remolded kaolin clay and St. Herblain clay. It is shown that the enhanced model can predict important features of soil viscous behavior, such as rate dependency of strength and preconsolidation pressure, relaxation, and creep.     

Simulating low flows over a heterogeneous landscape in southeastern Poland

This paper presents a scheme describing low flow formation processes in areas with different environmental conditions, including the impact of the selection and explanatory power of predictors for a probabilistic model based on the Logit model. The research was carried out using 29 daily streamflow gauges located in the Lublin region of southeastern Poland for the hydrological period 1976–2018. Analysis resulted in two distinct low flow schemes. In the lowland rivers, low flows occur during the warm season and are related to evaporation exceeding precipitation. In the upland rivers, hydrogeological factors related to water levels in the local Cretaceous aquifers determine the occurrence of low flows. This differentiation affects the quality of the predictive models. For lowland rivers, models based on the climatic water balance with a monthly shift have a better fit, while these models used for upland rivers are characterized by an approximately 10% decrease in accuracy. For upland rivers, the combined C_tH_t models without shifts produce the best model fit. The generalized precision of the Logit models is around 80%–90%.     

Deconstructing Italy: (Northern) Italians and their new perception of territoriality

The nineties will go down in Italian history as the decade of great political change. By way of emphasising this change, the media and politicians use the expressions `Prima Repubblica' and `Seconda Repubblica' (first and second republics), adopting the terminology used by the French for their `republics'. During the so-called First Republic (1948–1994), the centrist Christian Democrat Party represented the moderate political force in every government. However, the corruption trials of 1992–1993, which involved many of this party's members, led to its collapse at the ballot box. In northern Italy, a consequence of the demise of the Christian Democrats was the resounding success of the Lega Nord at the local government elections of 1993 and the general election of 1994. The Lega Nord based, and continues to base, its success on the use of ethno-nationalist slogans and catchcries. Italy has an ancient tradition – dating at least from the fall of the Roman Empire – of political and linguistic splintering. Given today's situation, this factor may have impacts at the level of the structure of the state: federalism, special statutes for regions and/or provinces, the decentralization of the state, and so on. For the first time for perhaps more than a century, in this new period of uncertain political change, Italians are increasingly viewing territory and its characteristics as politically relevant. Justifications for `national' cohesion are being rediscovered, or invented, at the local level, transforming it into political claims. Italians have begun to talk about relationships with territories and neighbouring groups from a different perspective. At present, traditional political parties and politicians are too slow and insufficiently focused in their response to the rising call for autonomy and decision-making authority at the local level. This factor has provided the time and space for isolationist and culturally self-reliant localist ideologies to propagate. It is impossible to say how long this period of transition will last and what its outcomes will be. The three main choices now facing Italians would be appear to be:(1) reclaim the nationalist sentiment of a united state (abandoned after the Fascist era);(2) provide the space (ideological and territorial) for the numerous localist nationalisms;(3) construct a real and flexible `localist' democracy for Italy as a whole.     

EARLY MODERN EXPANSION AND THE POLITICIZATION OF OCEANIC SPACE*

ABSTRACT. The definition of oceans as international politicized space is an integral but little analyzed aspect of early modern European expansion, which took place between about 1450 and 1800. In this essay I explore the implications of thinking about the development of European imperialism and global dominance in oceanic terms. I argue that oceanic, rather than terrestrial, dominance characterized early modern European empires, particularly in relation to Africa and Asia, where indigenous political and economic control prevailed. The long apprenticeship in mastering oceanic space contributed to the ability of Europeans to build land-based empires in Asia and Africa in the nineteenth century. As well, the international relationships worked out by Europeans in the nonstate but militarized arena of the high seas contributed to an emergent global order.     

The influence of Zihe Stream on the groundwater resources of the Dawu well field and on the discharge at the Heiwang iron mine, Zibo City area, Shandong Province, China

 The Dawu well field, one of the largest in China, supplies most of the water for the Zibo City urban area in Shandong Province. The field yields 522,400–535,400 m³/d from an aquifer in fractured karstic Middle Ordovician carbonate rocks. Much of the recharge to the aquifer is leakage of surface water from Zihe Stream, the major drainage in the area. Installation of the Taihe Reservoir in 1972 severely reduced the downstream flow in Zihe Stream, resulting in a marked reduction in the water table in the Dawu field. Since 1994, following the installation of a recharge station on Zihe Stream upstream from the well field that injects water from the Taihe Reservoir into the stream, the groundwater resources of the field have recovered. An average of 61.2×10³ m³/d of groundwater, mostly from the Ordovician aquifer, is pumped from the Heiwang iron mine, an open pit in the bed of Zihe Stream below the Taihe Reservoir. A stepwise regression equation, used to evaluate the role of discharge from the reservoir into the stream, confirms that reservoir water is one of the major sources of groundwater in the mine. Received, May 1998 / Revised, May 1999 / Accepted, June 1999     

基于面状要素拓扑关系的数据匹配技术研究

数据匹配技术是空间数据集成与融合中的关键技术。本文根据9交模型中的面状拓扑关系的描述,对面积叠置率进行了几何度量上的定义,提出了基于面积迭置率的数据匹配思路,实现了面状要素一对一、多对一、多对多的数据匹配。最后,以面状目标为研究对象,以城市居民地的大比例尺数据为例,对基于面积迭置率的面状要素数据匹配算法进行了试验与分析。     

Definitions of Natural-Language Spatial Relations： Combining Topology and Directions

Introduction Inmanyapplications(CADandgeographical informationsystem,GIS),dataaremanagedby spatialdatabases,whichstorepoint,line,region objectsandspatialrelationsbetweenthem.Spa tialrelations(topologicalrelations,directionre lationsandapproximatedistancer…     

拓扑关系和方向关系的定性组合描述

空间关系理论研究是当前GIS界重点研究的前沿课题之一,但就目前研究成果看,空间关系理论中的拓扑关系和方向关系的理论研究多采用独立的描述模型,影响了空间推理和空间表达的精度。该文在分析拓扑关系和方向关系描述模型的基础上,提出将拓扑关系和方向关系定性表示相结合的TD模型,并用实例说明该模型能较全面地描述空间对象的空间关系。     

On the RH relations across weak and strong shocks in van der Waals gases

The Rankine–Hugoniot (RH) jump relations for normal shock waves in van der Waals fluids have been studied in order to improve a theoretical understanding of those shock related phenomena as observed in a real atmosphere which cannot be accounted for by the ideal gas model. The RH jump relations for the pressure, density, particle velocity, temperature, speed of sound, adiabatic compressibility and change-in-entropy across the shock front have been analysed in terms of the non-idealness parameter of the gas, downstream Mach number and adiabatic index of the gas. Further, as the strength of shock waves may range from weak to strong, the convenient forms of RH jump relations for weak and strong shock waves have been discussed, simultaneously. Finally, the effects on the flow-field behind the shock front have been explored due to the non-idealness parameter of the gas, downstream Mach number and adiabatic index of the gas.     

Kinematic hardening plasticity formulation of small strain behaviour of soils

An objective of this paper is to demonstrate that the small strain model developed by the authors can be incorporated into the conventional kinematic hardening plasticity framework to predict pre‐failure defor mations. The constitutive model described in this paper is constituted by three elliptical yield surfaces in triaxial stress space. Two inner surfaces are rotated ellipses of the same shape, representing the boundaries of the linear elastic and small strain regions, while the third surface is the modified Cam clay large‐scale yield surface. Within the linear elastic region, the soil behaviour is elastic with cross‐coupling between the shear and volumetric stress–strain components. Within the small strain region, the soil behaviour is elasto‐plastic, described by the kinematic hardening rule with an infinite number of loading surfaces defined by the incremental energy criterion. Within the large‐scale yield surface, the soil behaviour is elasto‐plastic, described by kinematic and isotropic hardening of the small strain region boundary. Since the yield surfaces have different shapes, the uniqueness of the plastic loading condition imposes a restriction on the ratio between their semi‐diameters. The model requires 12 parameters, which can be determined from a single consolidated undrained triaxial compression test. Copyright © 2000 John Wiley & Sons, Ltd.