Ground water from the karstic Upper Floridan aquifer (UFA) is the sole source of water supply for Tallahassee, Florida, and surrounding areas of Leon County. the City of Tallahassee (City) currently operates 28 water-...
详细信息
ISBN:
(纸本)9780784410035
Ground water from the karstic Upper Floridan aquifer (UFA) is the sole source of water supply for Tallahassee, Florida, and surrounding areas of Leon County. the City of Tallahassee (City) currently operates 28 water-supply wells. Most of these wells yield an ample supply of potable water;however, low levels of tetrachloroethylene (PCE) have been found in water from several wells. the City removes the PCE from the water by passing it through granular-activated carbon units before distribution. To ensure that water-supply wells presently free of contamination remain PCE-free it is necessary to understand the ground-water flow system in sufficient detail to protect the contributing areas. the City cooperated withthe U.S. Geological Survey (USGS) in developing a ground-water flow model of the UFA to delineate contributing areas of water-supply wells and conduct age dating. Ground-water samples collected from four public-supply wells along a north-south transect were analyzed for tritium, helium-3, chlorofluorocarbons (CFCs), and sulfur hexafluoride (SF6). All three dating methods indicate that the apparent age of ground water generally decreases from northern to southern Leon County. this southward trend of decreasing ages is consistent with increasing amounts of recharge that occur as ground water moves from north to south. Ground-water age data derived by geochemical analyses were used in combination with ground-water flow modeling and particle tracking to determine an effective porosity for the Hawthorn clays and UFA. the Hawthorn clays range from a few meters thick to hundreds of meters thick and extend from land surface (or near land surface) down to the top of the UFA. the effective porosities for the UFA that resulted in best model matches were averaged to determine an average effective porosity of 7 percent, and the effective porosities for the Hawthorn clays that resulted in matches were also averaged to produce an effective porosity of 22 percent. Probabilis
the proceedings contain 125 papers. the topics discussed include: modeling the behavior of expansive clays;a constitutive model for undrained anisotropic behaviour of clays;response envelopes of the elasto-plastic S-C...
ISBN:
(纸本)0415408229
the proceedings contain 125 papers. the topics discussed include: modeling the behavior of expansive clays;a constitutive model for undrained anisotropic behaviour of clays;response envelopes of the elasto-plastic S-CLAY1 model;modelling small-strain stiffness withthe multilaminate framework;an evaluation of constitutive models to predict the behaviour of fine-grained soils with different degrees of overconsolidation;an elasto-plastic constitutive model for clays considering microstructure;a multilaminate model with destructuration;coupled analysis of an in situ experiment in a soft argillaceous rock using a new constitutive model;an elasto-plastic cap model for partially broken rock;and a generalized plasticity approach for describing the behaviour of silty soils forming the Venetian lagoon basin.
Paper describes results achieved during a 4 year european research project UPTUN GRD1-2001-40739, which finished in 2006. the objective of the project was to develop new methods and procedures for upgrading european t...
详细信息
ISBN:
(纸本)9780415440660
Paper describes results achieved during a 4 year european research project UPTUN GRD1-2001-40739, which finished in 2006. the objective of the project was to develop new methods and procedures for upgrading european tunnels and increasing their safety against fire accidents. Within the framework of this project authors contributed by developing and extending existing fracture-plastic material models for numerical modelling of structural behaviour subjected to fire. the behaviour of the model is demonstrated on simple uni-axial tests as well as on a three-dimensional analysis of a tunnel fire.
the solution-mined salt caverns can be utilized to store the natural gas and also the high-radioactive waste, so it is important to analyze the long-term stability of salt caverns. A user-defined creep constitutive mo...
详细信息
ISBN:
(纸本)9780415443982
the solution-mined salt caverns can be utilized to store the natural gas and also the high-radioactive waste, so it is important to analyze the long-term stability of salt caverns. A user-defined creep constitutive model is compiled as a dynamic link library (DLL) file that can be loaded whenever it is needed and implemented into the software FLAC ID. the stability after excavation and the law of the long-term volume convergence ratios of salt caverns selected in Jintan Salt Mine have been studied by the numerical method. the computation parameters are obtained from previous experimental results. the results show that the higher internal pressure will benefit the stability of salt caverns. the volume convergence ratios of salt caverns are below 22 percent as the running internal pressure of gas storage varies from 6 to 14.5 MPa. Based on the results of the numerical analysis, some useful advice has been provided for the construction and management of the gas storage in Jintan Salt Mine.
the well-known Cohesive Crack Model describes strain localization with a softening stress variation in concrete members subjected to tension. An analogous behaviour is also observed in compression, when strain localiz...
详细信息
ISBN:
(纸本)9780415440660
the well-known Cohesive Crack Model describes strain localization with a softening stress variation in concrete members subjected to tension. An analogous behaviour is also observed in compression, when strain localization takes place in a damaged zone and the stress reaches the compressive strength with surface energy dissipation. In the present paper, we propose the new concept of Overlapping Crack Model, which is analogous to the cohesive one and permits to simulate material compenetration. the two aforementioned elementary models are merged into a more complex algorithm able to describe both cracking and crushing growths during loading processes in RC members. A numerical procedure based on elastic coefficients is developed, taking into account the proposed constitutive laws in tension and compression. Withthis algorithm, it is possible to effectively capture the flexural behaviour of RC beams by varying the reinforcement percentage and/or the beam depth.
In a classical compression or tensile test using a Hopkinson bar, the stress-strain relation is obtained via the strain measurement on the bars. From the signals on the input and output bar the deformation and the str...
详细信息
ISBN:
(纸本)9780415440660
In a classical compression or tensile test using a Hopkinson bar, the stress-strain relation is obtained via the strain measurement on the bars. From the signals on the input and output bar the deformation and the stress in the specimen are calculated. In the case of spall experiments, the output bar vanishes and well-established methods cannot be applied. For this reason Schuler et al. 2006 developed a method for the measurement of the tensile strength and fracture energy in a spall experiment. the method is specified and analyzed via numerical simulations within this paper.
thin salt deposits present different solution mining issues than thick ones. For thin salts, traditional single-well plus annular casings solution mining methods are neither feasible nor economic. Here, we propose and...
详细信息
ISBN:
(纸本)9780415443982
thin salt deposits present different solution mining issues than thick ones. For thin salts, traditional single-well plus annular casings solution mining methods are neither feasible nor economic. Here, we propose and model the hydraulic coalescence solution mining method for thin salt deposits, based on circulation between wells linked through hydraulic fracturing, using the non-salt interfaces to constrain fracture propagation. Solution mining of salt is a chemico-thermal process, and the salt deposit will deform viscously under the combined effects of cavity growth and gravity-induced stresses during the mining process. this is clearly a thMC process (thermal, Hydrological, Mechanical, Chemical process). In this paper, the coupled thMC process is addressed theoretically, then a set of numerical simulations are carried out.
Electroporation is an effective alternative to viral methods to significantly improve DNA transfection after intradermal and topical delivery. We performed a series of in vivo experiments on rat skin using external pl...
详细信息
ISBN:
(纸本)9783540730439
Electroporation is an effective alternative to viral methods to significantly improve DNA transfection after intradermal and topical delivery. We performed a series of in vivo experiments on rat skin using external plate electrodes. the experiments showed that skin layers below stratum corneum can be permeabilized in this way. In order to study the course of skin tissue permeabilization by means of electric pulses, a numerical model was built, with COMSOL Multiphysics, using the finite element method. the model is based on the tissue-electrode geometry and electric pulses from our in vivo experiments. We took into account the layered structure of skin and changes of its bulk electric properties during electroporation, as observed in the in vivo experiments. We were using tissue conductivity values found in literature and experimentally determined electric field threshold values needed for tissue permeabilization. the results obtained withthe model were then compared to the in vivo results of gene transfection in rat skin and a good agreement was obtained. Withthe model presented we used the available data to try to explain the mechanism of the tissue electropermeabilization propagation beyond the initial conditions dictated by the tissue initial specific conductivities.
this research project aimed for the derivation of a consistent conversion formula between splitting tensile strength f(ct,sp) and uniaxial tensile strength f(ct) by applying methods of fracture mechanics. the derived ...
详细信息
ISBN:
(纸本)9780415440660
this research project aimed for the derivation of a consistent conversion formula between splitting tensile strength f(ct,sp) and uniaxial tensile strength f(ct) by applying methods of fracture mechanics. the derived conversion formula should encompass the entire spectrum of structural concretes used in practice. To achieve this target, an extensive experimental programme was carried out. Two normal strength, two high strength as well as two self-compacting concretes using different aggregates were tested. To analyse the obtained experimental results, the splitting tension tests and the uniaxial tension tests were modelled numerically. Both experimental and numerical test results showed that the uniaxial tensile strength f(ct) cannot be calculated from the splitting tensile strength f(ct,sp) using a single constant conversion factor. the main reason is due to the failure mechanism of the splitting tension test. Related fracture mechanical considerations are under development.
暂无评论