Advantages and limitations of an α-plasticity model for sand     

Sun  Yifei  Sumelka  Wojciech  Gao  Yufeng 《Acta Geotechnica》2020,15(6):1423-1437

Acta Geotechnica - The stress–strain response of sand was observed to depend on its material state, i.e., pressure and density. Successful modelling of such state-dependent response of sand...  相似文献   

The glacial landsystem of a tropical glacier: Charquini Sur,Bolivian Andes          下载免费PDF全文

Jakub Małecki  Harold Lovell  Wojciech Ewertowski  Łukasz Górski  Tomasz Kurczaba  Beata Latos  Michał Miara  Dorota Piniarska  Jacek Płocieniczak  Tomasz Sowada  Marcin Spiralski  Anna Warczachowska  Antoine Rabatel 《地球表面变化过程与地形》2018,43(12):2584-2602

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Reply to “Generation and propagation of transient nonlinear waves in a wave flume Wojciech Sulisz and Maciej Paprota 55:4 (2008) 277–287” [Coastal Engineering 56 (2009) 895–896]     

Wojciech Sulisz  Maciej Paprota 《Coastal Engineering》2010

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Generation and propagation of transient nonlinear waves in a wave flume     

Wojciech Sulisz  Maciej Paprota 《Coastal Engineering》2008

A semi-analytical nonlinear wavemaker model is derived to predict the generation and propagation of transient nonlinear waves in a wave flume. The solution is very efficient and is achieved by applying eigenfunction expansions and FFT. The model is applied to study the effect of the wavemaker and its motion on the generation and propagation of nonlinear waves. The results indicate that the linear wavemaker theory may be applied to predict only the generation of waves of low steepness for which the nonlinear terms in the kinematic wavemaker boundary condition and free-surface boundary conditions are of secondary importance. For waves of moderate steepness and steep waves these nonlinear terms have substantial effects on wave profile and wave spectrum just after the wavemaker. A wave spectrum corresponding to a sinusoidally moving wavemaker possesses a multi-peak form with substantial nonlinear components, which disturbs or may even exclude physical modeling in wave flumes. The analysis shows that the widely recognized weakly nonlinear wavemaker theory may only be applied to describe the generation and propagation of waves of low steepness. This is subject to further restrictions in shallow and deep waters because the kinematic wavemaker boundary condition as well as the nonlinear interaction of wave components and the evolution of wave energy spectrum is not properly described by weakly nonlinear wavemaker theory. Laboratory experiments were conducted in a wave flume to verify the nonlinear wavemaker model. The comparisons show a reasonable agreement between predicted and measured free-surface elevation and the corresponding amplitudes of Fourier series. A reasonable agreement between theoretical results and experimental data is observed even for fairly steep waves.  相似文献   

Non‐normality and induced plastic anisotropy under fractional plastic flow rule: a numerical study          下载免费PDF全文

Wojciech Sumelka  Marcin Nowak 《国际地质力学数值与分析法杂志》2016,40(5):651-675

In this paper, an implementation of fractional plastic flow rule in the framework of implicit and explicit procedures is under consideration. The fractional plastic flow rule is obtained from a generalisation of the classical plastic flow rule utilising fractional calculus. The key feature of this new concept is that in general, the non‐associative flow is obtained without necessity of additional potential assumption. If needed, the model can cover the anisotropy induced by plastic deformation. Illustrative examples showing the unusual flexibility of this model are also presented. Copyright © 2015 John Wiley & Sons, Ltd.  相似文献   

A Model to Simulate Pumping Tests in Wells with High Loss and Backflow     

M. Wojciech Kawecki 《Ground water》2011,49(3):445-449

Traditional methods of analyzing pumping tests in single wells fail when the well loss is very high due to a low transmissivity skin. Because of the restricted rate at which water can enter a high loss well from the aquifer, well casing storage becomes a significant factor. Additionally, if a slug of water enters the well from the pump column immediately after the pump is switched off, it has a long‐lasting significant effect on the recovering water level in the well because it cannot be absorbed rapidly by the aquifer. A theoretical model is derived here that simulates the water level in a well in these circumstances. In the model, the continuously changing rate of water inflow from the aquifer to the well is approximated by a step function with a finite difference time step. It is demonstrated by a real example that the model can be applied easily to analyze pumping tests, including tests with a varying pumping rate. The analysis confirms suspected high well loss, calculates the unknown rate of backflow, and determines the aquifer's transmissivity.  相似文献   

On the bulk parameterization of snow and its application to the quantitative studies of precipitation growth     

Wojciech W. Grabowski 《Pure and Applied Geophysics》1988,127(1):79-92

Appropriate formulation of bulk parameterization of snow growth and evaporation based on observational characteristics of snow particles is presented. The parameterization is compared to that of S. A. Rutledge and P. V. Hobbs and to detailed treatment in which snow particles are assumed to grow or evaporate in each size bin separately. On the contrary to bulk parameterization of rain, snow diffusional growth or evaporation is accurately represented in the suggested bulk formulation, but growth by riming is overpredicted. Integrations of water budget equations in a one-dimensional updraft have shown that quantitative results, e.g., precipitation intensity, cloudwater content, supersaturation with respect to ice, depend on the parameterization scheme employed, which suggests that comparisons of field measurements with parameterized model outputs is usually not straightforward.  相似文献   

Methods and models for dealing with spatial variability in soil and rock characterisation: design,management and related hazards     

Giovanna Vessia  Wojciech Pula 《Georisk: Assessment and Management of Risk for Engineered Systems and Geohazards》2015,9(4)

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Modelling of hydrogeochemical potential of three lake catchments in Polesie region (Eastern Poland)     

Jarosław Dawidek  Beata Ferencz  Wojciech Sobolewski 《水文研究》2013,27(12):1773-1780

Total dissolved solids (TDS) in lake and catchment water is a result of geological structure, as well as duration of rock and water contact and human activity. In this paper, a potential dissolved solids (PtDS) in three ??czna–W?odawa Lake catchments was determined using extraction and computer software (GIS and AquaChem). Human pressure on water quality was estimated as a difference of the TDS and a catchment hydrogeochemical potential (TPtDS, total potential dissolved solids). TPtDS coefficient included hydrogeological features of the aquifer, soil cover impact on infiltrated water quality, and sediments susceptibility to denudation. The main advantage of the model is a possibility of its employment for every catchment or other areas (e.g. administrative) on both microscale and mesoscale. The highest TPtDS occurred in the catchment, favoured with underground supply, which was located in the vicinity of the Cretaceous mesoregional unit (Che?m Hills). The lowest value was observed in the catchment built with organogenic sediments and coarse material. A seasonal constancy of TPtDS values proved a stability of the lake‐catchment systems under study. Copyright © 2012 John Wiley & Sons, Ltd.  相似文献   

Explicit stress integration with error control for the Barcelona Basic Model: Part I: Algorithms formulations     

Wojciech T. Sołowski  Domenico Gallipoli 《Computers and Geotechnics》2010,37(1-2):59-67

The numerical integration of the stress–strain relationship is an important part of many finite element code used in geotechnical engineering. The integration of elasto-plastic models for unsaturated soils poses additional challenges associated to the presence of suction as an extra constitutive variable with respect to traditional saturated soil models. In this contribution, a range of explicit stress integration schemes are derived with specific reference to the Barcelona Basic Model (BBM), which is one of the best known elasto-plastic constitutive models for unsaturated soils. These schemes, however, do not address possible non-convexity of the loading collapse (LC) curve and neglect yielding on the suction increase (SI) line. The paper describes eight Runge–Kutta methods of various orders with adaptive substepping as well as a novel integration scheme based on Richardson extrapolation. The algorithms presented also incorporate two alternative error control methods to ensure accuracy of the numerical integration. Extensive validation and comparison of different schemes are presented in a companion paper. Although the algorithms presented were coded for the Barcelona Basic Model, they can be easily adapted to other unsaturated elasto-plastic models formulated in terms of two independent stress variables such as net stress and suction.  相似文献