Angular deflection of rigid rectangular foundations on soil layer of finite thickness

G. V. Raskin

doi:10.1007/bf01703622

Closing the Energy Balance using a Canopy Heat Capacity – A physically based Approach for the Land Component JSBACHv3.11

10.5194/gmd-2018-17 ◽

2018 ◽

Author(s):

Marvin Heidkamp ◽

Andreas Chlond ◽

Felix Ament

Keyword(s):

Heat Capacity ◽

Energy Balance ◽

Diurnal Cycle ◽

Land Surface ◽

Climate Models ◽

Finite Thickness ◽

Soil Layer ◽

Surface Fluxes ◽

Delayed Response ◽

Stable Conditions

Abstract. Land surface-atmosphere interaction is one of the most important characteristic for understanding the terrestrial climate system, as it determines the exchange fluxes of energy and water between the land and the overlying air mass. In several current climate models, it is common practice to use an unphysical approach to close the surface energy balance within the uppermost soil layer with finite thickness and heat capacity. In this study, a different approach is investigated by means of a physical based estimation of the canopy heat capacity SkIn+. Therefore, in a first step, results of an offline simulation of the land component JSBACH of the MPI-ESM – constrained with atmospheric observations – are compared to energy- and water fluxes derived from eddy covariance measurements observed at the CASES-99 field experiment in Kansas where only shallow vegetation prevails. This comparison of energy and evapotranspiration fluxes with observations at the site-level provides an assessment of the model's capacity to correctly reproduce the coupling between the land and the atmosphere throughout the diurnal cycle. In a further step, a global coupled land-atmosphere experiment is performed using an AMIP type simulation over thirty years to evaluate the regional impact of the SkIn+ scheme on longer time scale, in particular, in respect to the effect of the canopy heat capacity. The results of the offline experiment show that SkIn+ leads to a warming during the day and to a cooling in the night relative to the old reference scheme, thereby improving the performance in the representation of the modeled surface fluxes on diurnal time scales. In particular: nocturnal heat releases unrealistically destroying the stable boundary layer disappear and phase errors are removed. On the global scale, for regions with no or low vegetation and a pronounced diurnal cycle, the nocturnal cooling prevails due to the fact that stable conditions at night maintain the delayed response in temperature, whereas the daytime turbulent exchange amplifies it. For the tropics and boreal forests as well as high latitudes, the scheme tends to warm the system.

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Closing the energy balance using a canopy heat capacity and storage concept – a physically based approach for the land component JSBACHv3.11

Geoscientific Model Development ◽

10.5194/gmd-11-3465-2018 ◽

2018 ◽

Vol 11 (8) ◽

pp. 3465-3479 ◽

Cited By ~ 3

Author(s):

Marvin Heidkamp ◽

Andreas Chlond ◽

Felix Ament

Keyword(s):

Heat Capacity ◽

Energy Balance ◽

Diurnal Cycle ◽

Heat Storage ◽

Finite Thickness ◽

Soil Layer ◽

Surface Fluxes ◽

Delayed Response ◽

Stable Conditions ◽

Physically Based

Abstract. Land surface–atmosphere interaction is one of the most important characteristic for understanding the terrestrial climate system, as it determines the exchange fluxes of energy and water between the land and the overlying air mass. In several current climate models, it is common practice to use an unphysical approach to close the surface energy balance within the uppermost soil layer with finite thickness and heat capacity. In this study, a different approach is investigated by means of a physically based estimation of the canopy heat storage (SkIn+). Therefore, as a first step, results of an offline simulation of the land component JSBACH of the Max Planck Institute Earth system model (MPI-ESM) – constrained with atmospheric observations – are compared to energy fluxes and water fluxes derived from eddy covariance measurements observed at the CASES-99 field experiment in Kansas, where shallow vegetation prevails. This comparison of energy and evapotranspiration fluxes with observations at the site-level provides an assessment of the model's capacity to correctly reproduce the diurnal cycle. Following this, a global coupled land–atmosphere experiment is performed using an AMIP (Atmospheric Model Intercomparison Project) type simulation over 30 years to evaluate the regional impact of the SkIn+ scheme on a longer timescale, in particular, with respect to the effect of the canopy heat storage. The results of the offline experiment show that SkIn+ leads to a warming during the day and to a cooling at night relative to the old reference scheme, thereby improving the performance in the representation of the modeled surface fluxes on diurnal timescales. In particular: nocturnal heat releases unrealistically destroying the stable boundary layer disappear and phase errors are removed. On the global scale, for regions with no or low vegetation and a pronounced diurnal cycle, the nocturnal cooling prevails due to the fact that stable conditions at night maintain the delayed response in temperature, whereas the daytime turbulent exchange amplifies it. For the tropics and boreal forests as well as high latitudes, the scheme tends to warm the system.

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Complex Variable Solution for Stress and Displacement of Layered Soil with Finite Thickness

Applied Sciences ◽

10.3390/app12020766 ◽

2022 ◽

Vol 12 (2) ◽

pp. 766

Author(s):

Xiangyu Sha ◽

Aizhong Lu ◽

Hui Cai ◽

Chonglin Yin

Keyword(s):

Finite Thickness ◽

Soil Layer ◽

Static Problem ◽

Surface Settlement ◽

Stress Fields ◽

Research Subject ◽

Analysis And Design ◽

Complete Contact ◽

Parametric Analyses ◽

Good Agreement

The static problem of a layered isotropic elastic body is a very useful research subject in relation to the analysis and design of foundation works. Due to the complexity of the problem, there is no analytical solution to the problem so far. This study provides an efficient analytical approach to accurately calculate the displacement and stress fields of the soil. The constraints of bedrock on soil, different soil layer thickness and the shear stress of the foundation on soil were all taken into account in the analysis. In this study, each layer is regarded as an isotropic elastomer with infinite width, and the layers are in complete contact. By using conformal mapping, each layer is mapped to a unit circle, and the two complex potential functions are expanded into Taylor series with unknown coefficients. These unknown coefficients are obtained by satisfying boundary conditions and continuity conditions. The boundary and continuity conditions were verified in this paper. As a validation step, we compared the analytical results for the settlement with the results of the ANSYS numerical simulations and found good agreement. Parametric analyses were also carried out to investigate the influence of different distribution forms of base pressure on surface settlement, and the effects of layered properties on the surface settlement and stress field.

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Deficient pore pressures in an eroding soil mass

Canadian Geotechnical Journal ◽

10.1139/t84-030 ◽

1984 ◽

Vol 21 (2) ◽

pp. 277-288 ◽

Cited By ~ 9

Author(s):

Sivajogi D. Koppula ◽

Norbert R. Morgenstern

Keyword(s):

Pore Pressure ◽

Moving Boundary ◽

Finite Thickness ◽

Soil Layer ◽

Free Water ◽

Soil Mass ◽

Bottom Boundary ◽

Pore Pressures ◽

Constant Rate ◽

Swelling Characteristics

The pore pressure response of a semi-infinite, fully saturated soil mass of finite thickness eroded at a constant rate is examined. Using Terzaghi's classical consolidation theory, an expression is derived for the deficient pore pressure as a function of depth and time. The resulting equation is mildly nonlinear with a moving top boundary. Closed form analytical solutions are obtained for various bottom boundary conditions and are presented in nondimensional quantities. The results indicate that the development of deficient pore pressures is dependent on (i) the rate of soil removal; (ii) the swelling potential of the soil mass; (iii) the ratio of the thickness of soil layer(s) removed to its original thickness; and (iv) the nature of the bottom boundary. Substantial negative pore pressures are likely to persist in the residual mass, even close to the eroded surface, although free water is made available at the top. The plots presented in this paper will be helpful for ascertaining the erosion–swelling characteristics of a soil mass that has been or is being eroded. Examples are presented to illustrate the development and dissipation of deficient pore pressures due to swelling. Keywords: constant rate, deficient pore pressures, depth factor, dredging, erosion–swelling ratio, isochrones, Laplace transform, moving boundary, swelling.

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The restoration of blurred electron micrographs

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100142529 ◽

1986 ◽

Vol 44 ◽

pp. 180-181

Author(s):

Bridget Carragher ◽

David A. Bluemke ◽

Michael J. Potel ◽

Robert Josephs

Keyword(s):

Cross Section ◽

Electron Micrographs ◽

Relative Motion ◽

Finite Thickness ◽

Image Plane ◽

Helical Axis ◽

Thin Sections ◽

Structural Details

We have investigated the feasibility of restoring blurred electron micrographs. Two related problems have been considered; the restoration of images blurred as a result of relative motion between the specimen and the image plane, and the restoration of images which are rotationally blurred about an axis. Micrographs taken while the specimen is drifting result in images which are blurred in the direction of motion. An example of rotational blurring arises in micrographs of thin sections of helical particles viewed in cross section. The twist of the particle within the finite thickness of the section causes the image to appear rotationally blurred about the helical axis. As a result, structural details, particularly at large distances from the helical axis, will be obscured.

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