The Evaluation Of Deformability Modulus By Rock Mass Classification Systems: A Comparative Study

The systems of classification of rock mass give, apart from useful qualitative and quantitative indications about the problems connected to the excavation of tunnels and the stability of slopes, also qualitative indications about the strength envelope and about deformability. This paper means to dwell upon the evaluation of deformability of rock masses by passing through the relations available in literature and by discussing the fundamental parameters on which these relations are based, which need to be verified with adequate in situ - tests. An application of some of literature relations to the Bari Limestone rock mass has been developed, on the basis of the achievements obtained through the use of the methods of classification of Bieniawski and Barton and by comparing the results obtained with the ones obtained from in situ tests. Key Words: Deformability modulus, Rock classification system

Methodological study on pesticides in Alsatian groundwater

The risk assessment conducted by many federal and state agencies have generally relied on deterministic approaches, that use single input/output values, generally selected to fulfill the goal of being health protective. But, the presence of uncertainty and variability within the parameters of the procedure of risk assessment let them assume different values within a range of possible values, each with different probability of occurrence. In particular, the case study deals with groundwater contamination by agrochemical substances occurring in the French aquifer of Alsace. The regional supply of drinking water, water for irrigation and industrial water depends mainly on this water resource. A proper management of this area must consider, thus, the sustainability of a landscape capable of multiple uses and the overwhelming presence of censored data. For this reason, particular attention is given to the characterization of the extent and the chemico-physical distribution of the pollutant source for what concern the delimitation of the hazardous areas, to the determination of the probability density functions of the concerned variables and of the representative concentrations

Laboratory tests to analyze solute transport behavior in fractured media

La conoscenza dei fenomeni di flusso e trasporto all'interno delle formazioni geologiche fratturate è molto importante al fine di ottimizzare la gestione delle risorse idriche di tali acquiferi. In questo lavoro si riportano i risultati di uno studio in cui sono stati effettuati differenti test di tracciamento su un campione di roccia fratturata artificialmente. Le curve di risposta sperimentali ottenute dalle prove di tracciamento sono state confrontate con due modelli analitici unidimensionali ossia: il modello classico di advezione e dispersione (ADE) e il modello mobile ed immobile (MIM). Quest'ultimo approssima maggiormente il comportamento sperimentale osservat

Characterization of a coastal fractured karstic aquifer by means of sequential indicator simulation algorithm

The characterization and the description of phenomena that involve fractured and karstic aquifers remains an open issue that calls the attention of numerous researchers belonging to different disciplinary fields as far as the aspects linked both to shallow and to subsoil phenomena are concerned. The geologic knowledge of these phenomena proves to be of high importance especially if considered in relationship with water resource exploitation, with the problems linked to contamination and the ones lined to urban and industrial development of the territory. The examined area is located in the city centre of Bari, inside a geomorphologically depressed zone named "lago di Marisabella" and is heavily contaminated by hydrocarbons. Nowadays thi s area is object of an intense scientific panel discussion because of issues linked to groundwater remediation as well as to the realization of a fill in the bend of Marisabella, located downstream to the examined area. The realization of the landfill has required the development of a detailed local scale hydrogeologic model in order to evaluate the effects on groundwater flow and contaminant propagation. The present work emphasizes the importance of the realization of a detailed geological model of the aquifer that supports the hydrogeologic model in that it permits to widen considerably the comprehension of fluid flow and solute transport phenomena; it can allow consequently to implement conceptually plausible numerical models that make use of adequate state variables (permeability, porosity, solution features) and boundary conditions adherent to reality. This permits to optimize any anthropic intervention that can involve this environmental matrix

Characterization of a coastal fractured karstic aquifer by means of sequential indicator simulation algorithm

The characterization and the description of phenomena that involve fractured and karstic aquifers remains an open issue that calls the attention of numerous researchers belonging to different disciplinary fields as far as the aspects linked both to shallow and to subsoil phenomena are concerned. The geologic knowledge of these phenomena proves to be of high importance especially if considered in relationship with water resource exploitation, with the problems linked to contamination and the ones lined to urban and industrial development of the territory. The examined area is located in the city centre of Bari, inside a geomorphologically depressed zone named "lago di Marisabella" and is heavily contaminated by hydrocarbons. Nowadays thi s area is object of an intense scientific panel discussion because of issues linked to groundwater remediation as well as to the realization of a fill in the bend of Marisabella, located downstream to the examined area. The realization of the landfill has required the development of a detailed local scale hydrogeologic model in order to evaluate the effects on groundwater flow and contaminant propagation. The present work emphasizes the importance of the realization of a detailed geological model of the aquifer that supports the hydrogeologic model in that it permits to widen considerably the comprehension of fluid flow and solute transport phenomena; it can allow consequently to implement conceptually plausible numerical models that make use of adequate state variables (permeability, porosity, solution features) and boundary conditions adherent to reality. This permits to optimize any anthropic intervention that can involve this environmental matrix

Kinematic diffusion approach to describe recharge phenomena in unsaturated fractured chalk

When dealing with groundwater resources, a better knowledge of the hydrological processes governing flow in the unsaturated zone would improve the assessment of the natural aquifer recharge and its vulnerability to contamination. In North West Europe groundwater from unconfined chalk aquifers constitutes a major water resource, therefore the need for a good hydrological understanding of the chalk unsaturated zone is essential, as it is the main control for aquifer recharge. In the North Paris Basin, much of the recharge must pass through a regional chalk bed that is composed of a porous matrix with embedded fractures. The case study regards the role of the thick unsaturated zone of the Cretaceous chalk aquifer in Picardy (North of France) that controls the hydraulic response to rainfall. In order to describe the flow rate that reaches the water table, the kinematic diffusion theory has been applied that treats the unsaturated water flow equation as a wave equation composed of diffusive and gravitational components. The kinematic diffusion model has proved to be a convenient method to study groundwater recharge processes in that it was able to provide a satisfactory fitting both for rising and falling periods of water table fluctuation. It has also proved to give an answer to the question whether unsaturated flow can be described using the theory of kinematic waves. The answer to the question depends principally on the status of soil moisture. For higher values of hydraulic Peclet number (increasing saturation), the pressure wave velocities dominate and the preferential flow paths is provided by the shallow fractures in the vadose zone. With decreasing values of hydraulic Peclet number (increasing water tension), rapid wave velocities are mostly due to the diffusion of the flow wave. Diffusive phenomena are provided by matrix and fracture-matrix interaction. The use of a kinematic wave in this context constitutes a good simplified approach especially in cases when there is a lack of information concerning the hydraulic properties of the fractures/macropores close to saturation

Laboratory tests to analyze solute transport behavior in fractured media

La conoscenza dei fenomeni di flusso e trasporto all'interno delle formazioni geologiche fratturate è molto importante al fine di ottimizzare la gestione delle risorse idriche di tali acquiferi. In questo lavoro si riportano i risultati di uno studio in cui sono stati effettuati differenti test di tracciamento su un campione di roccia fratturata artificialmente. Le curve di risposta sperimentali ottenute dalle prove di tracciamento sono state confrontate con due modelli analitici unidimensionali ossia: il modello classico di advezione e dispersione (ADE) e il modello mobile ed immobile (MIM). Quest'ultimo approssima maggiormente il comportamento sperimentale osservat

Analysis of gravel back-filled borehole heat exchanger in karst fractured limestone aquifer at local scale

In designing and sizing of borehole thermal energy system, natural groundwater movement and temperature driven flow have a great importance on the borehole heat exchanger efficiency. The efficiency of double U – tube arrangement in gravel – backfilled borehole installed in a fractured limestone aquifer has been analyzed by means of three – dimensional numerical simulations. The numerical model is representative of 1 m deep of gravel back – filled borehole surrounded by the fractured aquifer. Several simulations have been carried out in order to evaluate the effect of aquifer parameters and boundary conditions on heat exchange efficiency by varying the mean temperature within the double U - tube. The fractured limestone aquifer of the industrial area of Bari (Italy) has been chosen as field site in order to identify the aquifer parameter range and the respective combinations. The results highlight that borehole thermal energy system efficiency is strictly dependent on aquifer transmissivity and groundwater Darcian velocity. The conducted analysis shows that, under lower Darcian groundwater flow and lower aquifer transmissivity, heat transfer efficiency increases at least by 25% compared to stagnant water, whereas heat transfer in the aquifer is governed by heat conduction. The increase of aquifer transmissivity induces the thermosiphon effect enhancing heat transfer processes both in the gravel back-filled borehole and aquifer. At higher values of groundwater Darcian velocity (> 0.1 m/d) advection due to groundwater flow is not negligible and mixed with free convection enhancing heat transfer further. Based on the results, discussion on the performance and environmental constraint of gravel back – filled borehole at field site has been presented