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The response of saturated porous medium is of significant interest in many fields ranging from geomechanics to biomechanics. Biot was the first to formulate the basic equations governing the process of coupled flow and deformation in porous media. Depending on the nature of loading vis‐à‐vis the characteristics of the media, different formulations (fully dynamic, partly dynamic, quasi‐static) are possible. In this study, analytical solutions are developed for the response of saturated and nearly saturated porous media under plane strain condition. The solutions for different formulations are developed in terms of non‐dimensional parameters. The response is studied for various conditions and the regions of validity for various formulations are identified in a parametric space. An assessment of the needed formulation for few important problems is also presented. Copyright © 2008 John Wiley & Sons, Ltd. 相似文献
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In this study the effect of cyclic loads on monotonic shear strength has been studied on torsional apparatus. Tests have been conducted on both reconstituted and undisturbed fine-grained hollow soil specimens. The plasticity index of soils is in the range from 2 to 33 for reconstituted specimens, prepared by dry pluviation, and from 5 to 13 for undisturbed soil specimens. The existence of a critical shear strain level, called yield shear strain, where softening starts, is determined from cyclic tests. The level of cyclic yield strain is ± 0.75% for the reconstituted soil specimens and ± 0.5% for the undisturbed soils. If soil undergoes a cyclic shear strain level below the cyclic yield strain, reduction of monotonic strength of reconstituted and undisturbed specimens is limited, but when cyclic shear strain level is larger than yield strain monotonic strength decreases down to 40% of its initial strength. 相似文献
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Adaptive Neuro-Fuzzy Inference System for drought forecasting 总被引：3，自引：2，他引：1
Ulker Guner Bacanli Mahmut Firat Fatih Dikbas 《Stochastic Environmental Research and Risk Assessment (SERRA)》2009,23(8):1143-1154
Drought causes huge losses in agriculture and has many negative influences on natural ecosystems. In this study, the applicability
of Adaptive Neuro-Fuzzy Inference System (ANFIS) for drought forecasting and quantitative value of drought indices, the Standardized
Precipitation Index (SPI), is investigated. For this aim, 10 rainfall gauging stations located in Central Anatolia, Turkey
are selected as study area. Monthly mean rainfall and SPI values are used for constructing the ANFIS forecasting models. For
all stations, data sets include a total of 516 data records measured between in 1964 and 2006 years and data sets are divided
into two subsets, training and testing. Different ANFIS forecasting models for SPI at time scales 1–12 months were trained
and tested. The results of ANFIS forecasting models and observed values are compared and performances of models were evaluated.
Moreover, the best fit models have been also trained and tested by Feed Forward Neural Networks (FFNN). The results demonstrate
that ANFIS can be successfully applied and provide high accuracy and reliability for drought forecasting. 相似文献
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In this study, a set of generalized analytical solutions are developed for the wave-induced response of a saturated porous seabed under plane strain condition. When considering the water waves originating in deep water and travelling towards the shore, their velocities, lengths and heights vary. Depending on the characteristics of the wave and the properties of the seabed, different formulations (fully dynamic, partly dynamic, quasi-static) for the wave-induced response of the seabed are possible. The solutions for the response with these formulations are established in terms of non-dimensional parameters. The results are presented in terms of pore pressure, shear stress and vertical effective stress distributions within the seabed. For typical values of wave period and seabed permeability, the regions of applicability of the three formulations are identified and plotted in parametric spaces. With given wave and seabed characteristics, these regions provide quick identification of the appropriate formulation for an adequate evaluation of the wave-induced seabed response. 相似文献
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Ismet Gul Buyruklardan Kaya Dilek Duranoglu Ulker Beker Bahire Filiz Senkal 《洁净——土壤、空气、水》2011,39(11):980-988
Ferric oxide‐loaded hybrid sorbents are environmentally benign and exhibit sorption behaviors for chromium removal from waters. In the current study, glycidyl methacrylate‐based polymer (GMD) and nanosized ferric oxide loaded glycidyl methacrylate‐based polymer (GMDFe) were prepared and assayed to examine the effect of ferric oxide loading on chromium sorption from aqueous solution for the first time from the equilibrium and kinetic points of view. The experimental equilibrium data, suitably fitted by the Langmuir and Freundlich isotherms, have shown that ferric oxide loaded hybrid sorbent exhibits higher adsorption capacity than glycidyl methacrylate‐based polymer (GMD). The Langmuir isotherm model was found to be the most suitable one for the Cr(VI) adsorption. The maximum adsorption capacities of GMD and GMDFe sorbents were determined at pH 4 as 109.54 and 157.52 mg/g, respectively. A series of column experiments was carried out to determine the breakthrough curves. The column was regenerated by eluting Cr(VI) using NaOH (10% w/v) solution after adsorption studies. 相似文献
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Breaking‐wave‐induced dynamic response and instability of seabed around a caisson breakwater are investigated. A seabed‐rubble‐breakwater system is modeled using finite elements. The impact response of the porous seabed and rubble foundation is assumed to be governed by the coupled Biot equations, and three possible formulations are considered with respect to the inclusion of inertial terms. The response is presented in terms of shear stress and pore pressure distributions at three locations underneath the breakwater. The effect of seabed and wave parameters and the inertial terms on the impact response is investigated through parametric studies. Analyses show that usually partly dynamic formulation yields the largest response amplitudes as compared to the fully dynamic formulation, which is the most complete form. The instability of seabed and rubble mound as a result of instantaneous liquefaction is also studied. Breaking wave‐induced pressures in some cases are found to cause liquefaction in the rubble and the seabed. The effect of some parameters on the instability is found to be significant. Copyright © 2011 John Wiley & Sons, Ltd. 相似文献
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