This paper introduced a novel microstructure-based constitutive model designed to comprehensively characterize the intricate mechanical behavior of anisotropic clay rocks under the influence of water saturation.The pr...This paper introduced a novel microstructure-based constitutive model designed to comprehensively characterize the intricate mechanical behavior of anisotropic clay rocks under the influence of water saturation.The proposed model encompasses elastoplastic deformation,time-dependent behavior,and induced damage.A two-step homogenization process incorporates mineral compositions and porosity to determine the macroscopic elastic tensor and plastic yield criterion.The model also considers interfacial debonding between the matrix and inclusions to capture rock damage.The application of the proposed model is demonstrated through an analysis of Callovo-Oxfordian clayey rocks,specifically in the context of radioactive waste disposal in France.Model parameters are determined,followed by numerical simulations of various laboratory tests including lateral decompression tests with constant mean stress,triaxial compression tests under different water saturation conditions,and creep tests.The numerical results are compared with corresponding experimental data to assess the efficacy of the proposed model.展开更多
This study aims at determining the quantitative effect of pesticides including 2, 4-D dichlorphenoxy acetic acids, Paraquat, Atrazine (2-chloro-4-ethylamino-6-isopropylamino-striazine), and MCPP 2-(2-Methyl-4-chloroph...This study aims at determining the quantitative effect of pesticides including 2, 4-D dichlorphenoxy acetic acids, Paraquat, Atrazine (2-chloro-4-ethylamino-6-isopropylamino-striazine), and MCPP 2-(2-Methyl-4-chlorophenoxy) pro-panioic acid on groundwater quality due to agricultural in Jenin and Tulkarem, northern part of the West Bank. The concentrations of pesticides in Jenin was found to be higher than those in Tulkarem where the majority of the samples taken had concentration 10 μg/L. It is concluded that the contamination of the tested wells was due to pesticides and not wastewater disposal, since most of the samples were free from pathogenic indicators. Results revealed that using these wells for drinking purposes has a potentially high health risk. This is mainly due to the uncontrolled industrial and agricultural activity as well as the lack of monitoring. Concentrations of heavy metals including cadmium (Cd), lead (Pb), iron (Fe), zinc (Zn), chromium (Cr) and copper (Cu) were also quantitatively determined for the same period extending from April, 2004 to May, 2005. Concentrations of Pb and Cr in most of the tested wells in Tulkarem complied with the WHO guideline;while nitrate (NO3) and potassium (K) concentrations exceeded the permissible concentra-tions.展开更多
This paper presents an efficient numerical tool for the prediction of railway dynamic response.A behavior calibration of the infinite Euler-Bernoulli beam resting on continuous viscoelastic foundation is proposed.Cons...This paper presents an efficient numerical tool for the prediction of railway dynamic response.A behavior calibration of the infinite Euler-Bernoulli beam resting on continuous viscoelastic foundation is proposed.Constitutive laws of the discrete elements are determined for a rectilinear ballasted track.A three-dimensional model coupled with an adaptive meshing scheme is employed to calibrate the beam model impedances by finding the similarity between the output signals using the genetic algorithm.The model shows an important performance with significant reduction in computational effort.This study emphasizes the major impact of the excitation characteristics on the parameters of the discrete models.展开更多
Spring recession flows are analyzed from a Bayesian point of view. Two general equations are derived and it is shown that the classical formulas of recession flow are particular cases of both equations. It is shown th...Spring recession flows are analyzed from a Bayesian point of view. Two general equations are derived and it is shown that the classical formulas of recession flow are particular cases of both equations. It is shown that most of the recession equations reflect a non-Markovian process. That means that the groundwater storage exhibits a memory effect and that there is a nonlinear relationship between flow and storage. The Bayesian approach presented in this paper makes it possible to give a probabilistic meaning to recession flow equations derived according to a physical approach and can be an alternative to the study of complex reservoir for which the physical processes governing recession flow are unclear. Twelve spring recession flow series are analysed in order to validate the probabilistic approach presented in this paper and a conceptual model of storage-outflow is proposed.展开更多
Annual maximum rainfall intensity for several duration and return periods has been analyzed according to the Gumbel distribution. The Intensity-Duration-Frequency (IDF) curves before and after 1980 have been computed ...Annual maximum rainfall intensity for several duration and return periods has been analyzed according to the Gumbel distribution. The Intensity-Duration-Frequency (IDF) curves before and after 1980 have been computed and compared. For the city of Toronto, it is shown that the rainfall intensities after 1980 are lower than those from before this date. This is especially clear for those of short duration. Comparing our results with those of other authors, it appears that, for the moment, no general law on the impact of global warming on the curves intensity duration frequency cannot be made. It appears that the impact of global warming on rainfall varies with geographic location and that it is not possible to draw some general conclusions across the planet.展开更多
A macroscopic yield criterion has been derived in the present work for a double saturated porous medium with a spheroidal pore at the mesocale and spherical pores at the microscale.These two types of pores are well se...A macroscopic yield criterion has been derived in the present work for a double saturated porous medium with a spheroidal pore at the mesocale and spherical pores at the microscale.These two types of pores are well separated at two different scales.The meso spheroidal pore saturated by a pore pressure which is different from the one in the micro spherical pores.A Drucker-Prager type criterion is adopted for the solid phase at the microscopic scale to describe its asymmetric behavior between tension and compression.The methodology to formulate this criterion is based on the limit analysis approach of a spheroidal volume containing a confocal spheroidal pore subjected to a uniform strain rate boundary conditions.The matrix at the mesoscopic scale obeys to a general elliptic yield criterion.Based on a two-step homogenization step,the influence of meso-pore shape(spherical,prolate or oblate),micro-porosity,meso-porosity and the effect of pore pressures at different scales are taken into account explicitly by this macroscopic yield criterion.展开更多
The numerical modelling of the excavation of an underground gallery in hard clay has been discussed in current article.A constitutive model is proposed to describe poromechanical behaviour of the hard clay.The main fe...The numerical modelling of the excavation of an underground gallery in hard clay has been discussed in current article.A constitutive model is proposed to describe poromechanical behaviour of the hard clay.The main features of the hard clay observed in laboratory and in-situ experimental investigation have been taken into account in the proposed constitutive model,in particular the plastic deformation,the visco-plastic deformation,the damage,etc.The influence of the initial in-situ stress and the pore pressure has been taken into consideration.The numerical modelling of the underground excavation has been implemented by using a fully coupled hydro-mechanical finite element calculation code.The performance of the model is examined by comparing numerical simulations with in situ measurements.The proposed model and the calculation procedure for the modelling of the excavation of an underground gallery have the capacity to reproduce well the excavation damaged/distributed zone and other main features and phenomena observed during the excavation process.However,the in-situ observed convergence could not be reproduced correctly.More effort on the discontinuous problem should be made for the reproduce the observed convergence.展开更多
文摘This paper introduced a novel microstructure-based constitutive model designed to comprehensively characterize the intricate mechanical behavior of anisotropic clay rocks under the influence of water saturation.The proposed model encompasses elastoplastic deformation,time-dependent behavior,and induced damage.A two-step homogenization process incorporates mineral compositions and porosity to determine the macroscopic elastic tensor and plastic yield criterion.The model also considers interfacial debonding between the matrix and inclusions to capture rock damage.The application of the proposed model is demonstrated through an analysis of Callovo-Oxfordian clayey rocks,specifically in the context of radioactive waste disposal in France.Model parameters are determined,followed by numerical simulations of various laboratory tests including lateral decompression tests with constant mean stress,triaxial compression tests under different water saturation conditions,and creep tests.The numerical results are compared with corresponding experimental data to assess the efficacy of the proposed model.
文摘This study aims at determining the quantitative effect of pesticides including 2, 4-D dichlorphenoxy acetic acids, Paraquat, Atrazine (2-chloro-4-ethylamino-6-isopropylamino-striazine), and MCPP 2-(2-Methyl-4-chlorophenoxy) pro-panioic acid on groundwater quality due to agricultural in Jenin and Tulkarem, northern part of the West Bank. The concentrations of pesticides in Jenin was found to be higher than those in Tulkarem where the majority of the samples taken had concentration 10 μg/L. It is concluded that the contamination of the tested wells was due to pesticides and not wastewater disposal, since most of the samples were free from pathogenic indicators. Results revealed that using these wells for drinking purposes has a potentially high health risk. This is mainly due to the uncontrolled industrial and agricultural activity as well as the lack of monitoring. Concentrations of heavy metals including cadmium (Cd), lead (Pb), iron (Fe), zinc (Zn), chromium (Cr) and copper (Cu) were also quantitatively determined for the same period extending from April, 2004 to May, 2005. Concentrations of Pb and Cr in most of the tested wells in Tulkarem complied with the WHO guideline;while nitrate (NO3) and potassium (K) concentrations exceeded the permissible concentra-tions.
文摘This paper presents an efficient numerical tool for the prediction of railway dynamic response.A behavior calibration of the infinite Euler-Bernoulli beam resting on continuous viscoelastic foundation is proposed.Constitutive laws of the discrete elements are determined for a rectilinear ballasted track.A three-dimensional model coupled with an adaptive meshing scheme is employed to calibrate the beam model impedances by finding the similarity between the output signals using the genetic algorithm.The model shows an important performance with significant reduction in computational effort.This study emphasizes the major impact of the excitation characteristics on the parameters of the discrete models.
文摘Spring recession flows are analyzed from a Bayesian point of view. Two general equations are derived and it is shown that the classical formulas of recession flow are particular cases of both equations. It is shown that most of the recession equations reflect a non-Markovian process. That means that the groundwater storage exhibits a memory effect and that there is a nonlinear relationship between flow and storage. The Bayesian approach presented in this paper makes it possible to give a probabilistic meaning to recession flow equations derived according to a physical approach and can be an alternative to the study of complex reservoir for which the physical processes governing recession flow are unclear. Twelve spring recession flow series are analysed in order to validate the probabilistic approach presented in this paper and a conceptual model of storage-outflow is proposed.
文摘Annual maximum rainfall intensity for several duration and return periods has been analyzed according to the Gumbel distribution. The Intensity-Duration-Frequency (IDF) curves before and after 1980 have been computed and compared. For the city of Toronto, it is shown that the rainfall intensities after 1980 are lower than those from before this date. This is especially clear for those of short duration. Comparing our results with those of other authors, it appears that, for the moment, no general law on the impact of global warming on the curves intensity duration frequency cannot be made. It appears that the impact of global warming on rainfall varies with geographic location and that it is not possible to draw some general conclusions across the planet.
文摘A macroscopic yield criterion has been derived in the present work for a double saturated porous medium with a spheroidal pore at the mesocale and spherical pores at the microscale.These two types of pores are well separated at two different scales.The meso spheroidal pore saturated by a pore pressure which is different from the one in the micro spherical pores.A Drucker-Prager type criterion is adopted for the solid phase at the microscopic scale to describe its asymmetric behavior between tension and compression.The methodology to formulate this criterion is based on the limit analysis approach of a spheroidal volume containing a confocal spheroidal pore subjected to a uniform strain rate boundary conditions.The matrix at the mesoscopic scale obeys to a general elliptic yield criterion.Based on a two-step homogenization step,the influence of meso-pore shape(spherical,prolate or oblate),micro-porosity,meso-porosity and the effect of pore pressures at different scales are taken into account explicitly by this macroscopic yield criterion.
基金This work has been partially supported by the ANDRA,which is gratefully acknowledged.
文摘The numerical modelling of the excavation of an underground gallery in hard clay has been discussed in current article.A constitutive model is proposed to describe poromechanical behaviour of the hard clay.The main features of the hard clay observed in laboratory and in-situ experimental investigation have been taken into account in the proposed constitutive model,in particular the plastic deformation,the visco-plastic deformation,the damage,etc.The influence of the initial in-situ stress and the pore pressure has been taken into consideration.The numerical modelling of the underground excavation has been implemented by using a fully coupled hydro-mechanical finite element calculation code.The performance of the model is examined by comparing numerical simulations with in situ measurements.The proposed model and the calculation procedure for the modelling of the excavation of an underground gallery have the capacity to reproduce well the excavation damaged/distributed zone and other main features and phenomena observed during the excavation process.However,the in-situ observed convergence could not be reproduced correctly.More effort on the discontinuous problem should be made for the reproduce the observed convergence.
