1,721,025 research outputs found
Application of high resolution shear wave seismic methods for a geotechnical problem
No full textApplied geophysical techniques in
underground exploration can be useful in defining
the subsoil geometry and the spatial relationships of
the physico–mechanical properties of the materials.
An example is presented to demonstrate how highresolution
seismic techniques using shear waves can
assist with a geotechnical issue. The survey has been
carried out to elucidate the subsoil geometry and
characterize lithotypes in terms of physicomechanical
parameters, useful in the geotechnical
study of an historic monument in which fractures
developed following a downslope excavation
Application of high resolution shear wave seismic methods to a geotechnical problem
No full textApplied geophysical techniques in
underground exploration can be useful in defining
the subsoil geometry and the spatial relationships of
the physico–mechanical properties of the materials.
An example is presented to demonstrate how highresolution
seismic techniques using shear waves can
assist with a geotechnical issue. The survey has been
carried out to elucidate the subsoil geometry and
characterize lithotypes in terms of physicomechanical
parameters, useful in the geotechnical
study of an historic monument in which fractures
developed following a downslope excavation
VSP processed down-hole data within local seismic response assessment
No full textLocal effects evaluation may be solved using different methodological ways. VEL Project of Tuscany district
approach, foresees the evaluation of the surface effects in a specified zone of a "forecasted" earthquake, through geological,
geomorphologic, geotechnical, geophysical and numerical modelling. The knowledge of bedrock depth and geometry is a
fundamental issue in such a multidisciplinary integrated approach. Down-hole tests carried out in not sufficiently deep
borehole to reach bedrock, have been processed as VSP (Vertical Seismic Profiling) method, allowing the knowledge of
bedrock depth. This has been obtained developing a processing aimed to the study of reflected signals that provided
important information on discontinuities occurring below the borehole bottom. Results obtained by VSP processing from
conventional SH waves down-hole data, have been calibrated by comparison with an high-resolution shear wave reflection
line carried out in the same site. This comparison provided new cognitive elements and work prospects
Power-law frequency distribution of H/V spectral ratio of seismic signals: Evidence for a critical crust.
No full textTime cross-sections generated from shallow seismic refraction data: preliminary results
No full textShallow refraction seismic survey is a very common and useful subsurface investigation method. However, traditional shallow seismic refraction processing methods show long-standing limitations due to the almost complete reliance on the first arrival signal. On the other hand, full wave form processing of data can by-pass inherent limitations and improve the imaging of the subsurface. In this sense, better results can be achieved through digital processing that has been successfully developed in reflection seismology. In particular, a time cross-section, similar to the well known reflection cross-section, can be generated through tools like CMP stacking that improves the signal-to-noise ratio. Other tools imply deconvolution and migration for improvement of, respectively, vertical and lateral resolution. Muting and dip filtering for deletion of coherent noise. This note presents a discussion on the feasibility of this kind of approach. Time cross-sections obtained with these methods are shown and compared with a HR reflection section
Advanced redox zonation of the San Pedro Sula alluvial aquifer (Honduras) using data fusion and multivariate geostatistics
Full text linkThe incorrect wastewater management and the land use distribution lead to severe environmental problems, creating heavy eutrophication condition in surface-water; when surface-water/groundwater relationships exist, the organic matter transferred to the aquifer oxidizes and triggers redox processes (i.e. Terminal Electron Accepting Processes, TEAPs), that provoke severe groundwater quality modifications and complicate its exploitation and management. For this reason, the definition of the redox zonation within an aquifer is an effective tool for the identification of the contamination sources and for the conceptual model refinement, when remediation strategies need to be planned. Although the redox processes are dynamic reactions, the aquifer redox zonation is generally aimed to identify homogenous zones, characterized by a predominant TEAP. To overcome this methodological approach, the Multi-Collocated Factorial Kriging (MCFK) was applied to redox-related physico-chemical parameters, which allowed identifying their spatial relationships at different scales, transferring this method from precision agriculture and soil science to hydrogeochemistry. The selected study area is the San Pedro Sula aquifer (Honduras), a multi-layer alluvial aquifer characterized by well-known surface-water/groundwater interactions and heavy eutrophicated streams. Here, high concentrations of Mn and Fe were found in the aquifer. The MCFK results identified a short-range (2300 m) factor, highlighting a strong relation between Mn concentrations and anoxic conditions, due to the organic matter transfer from eutrophicated surface-water into the aquifer. Simultaneously, the relationship between Fe and turbidity is related to a fine Fe(III) oxi-hydroxide colloidal phase, developed when different redox conditions of groundwater mix up in the wells. The long-range (6000 m) factor points out that Fe is related to redox processes at a wider scale, especially in the northern San Pedro Sula alluvial plain. These results are supported by both the Principal Component Analysis and the hydrogeochemical numerical modeling. As a result, different TEAPs occur simultaneously in contaminated areas, acting at multiple scales
Un’applicazione di metodologie sismiche ad alta risoluzione con onde di taglio per la risoluzione di una problematica di tipo geotecnico
No full text
Metodi geofisici integrati per la ricostruzione del sottosuolo e per la caratterizzazione dinamica dei terreni negli studi di microzonazione sismica: l’esempio di Pieve Fosciana (LU)
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