- Home
- Conferences
- Conference Proceedings
- Conferences
Near Surface 2005 - 11th European Meeting of Environmental and Engineering Geophysics
- Conference date: 04 Sep 2005 - 07 Sep 2005
- Location: Palermo, Italy
- Published: 04 September 2005
21 - 40 of 180 results
-
-
Audiomagnetotelluric Sounding (AMTS) at Shallow Depths to Predict Accumulations of Oil-Gas Condensate Raw Stock
Authors E.M. Sheremet, A.V. Antsiferov, V.V. Sukhoi, Y.I. Nikolaev and I.Y. NikolaevA025 Audiomagnetotelluric sounding (AMTS) at shallow depths to predict accumulations of oilgas condensate raw stock Abstract 1 A.V. ANTSIFEROV E.M. SHEREMET V.V. SUKHOI YU.I. NIKOLAEV I.YU. NIKOLAEV Ten-year experience of using AMTS method within the Dnieper-Donets cavity (DDC) of Ukraine to predict and prospect for accumulations of oil-gas condensate raw stock has allowed to create efficient technique of field observations and geoelectric data processing. The employment of AMTS method which resolution throughout the depth is 0.5-2.0 km is based on the observations of the epigenetic transformation of rocks occurring above the oil pool. In the process of epigenetic transformations of
-
-
-
Localization of a Karst Conduit Using Magnetic Resonance Soundings – A Case Study
Authors M. Boucher, K. Chalikakis, J.-M. Baltassat, A. Legchenko and J.-F. GirardA027 Localization of a karst conduit using Magnetic Resonance Soundings a case study Abstract 1 Initially developed for one-dimensional applications Magnetic Resonance Soundings (MRS) technique can be also applied to investigation of two or three dimensional water-filled structures like karst conduits and caves. Numerical modeling reveals that MRS is able to detect water-filled karst. Based on these results field experiments were carried out. The aim of presented experimental study was to validate MRS 2D mathematical model and to develop a methodology of acquisition and interpretation of MRS profile over a karst conduit. It was found that results of 2D inversion
-
-
-
1D and 2D Cole-Cole-Inversions of Time Domain Induced Polarisation Data
More LessA028 1D AND 2D COLE-COLE-INVERSIONS OF TIME DOMAIN INDUCED POLARISATION DATA Summary 1 A new method for the 2D inversion of induced polarization (IP) data in the time domain has been developed. The whole IP transients were observed and inverted into 2D Cole-Cole earth models including resistivity chargeability relaxation time and the frequency constant. First of all a modified time domain electromagnetic algorithm was used to calculate the response of a layered polarizable ground. The transient signals were then inverted using the Marquardt-method to derive the Cole-Cole parameters of each layer. However model calculations showed that the EM effects could
-
-
-
Implementation to Back-Projection Techniques of Resistivity Data
Authors R. Martorana and P.L. CosentinoA029 IMPLEMENTATION TO BACK-PROJECTION TECHNIQUES OF RESISTIVITY DATA Summary 1 In order to obtain well contrasted images by back-projection of resistivity data some modifications to the back-projection algorithm as well as the use of filtering techniques for the sensitivity matrix were proposed (Kotre 1994; Cosentino et al. 1998). To further improve the back-projection algorithm a new implementation is here suggested. Besides a subsequent filtering algorithm of the sensitivity coefficient matrix is proposed. It is aimed to increase resistivity contrasts and to reduce smoothness in tomographic final representation. Finally the proposed technique is tested on synthetic data. Introduction The back-projection resistivity
-
-
-
Non-Linear Resistivity Inversion on 3D Structures with Complex Shapes
Authors L. Marescot, S. Palma Lopes, S. Rigobert, R. Lagabrielle and D. ChapellierA030 NON-LINEAR RESISTIVITY INVERSION ON 3D STRUCTURES WITH COMPLEX SHAPES Summary 1 A non-linear inversion code was presented for the processing of resistivity tomographies on complex 3-D structures using any electrode arrangement. This algorithm uses an original strategy (adjoint-state technique) to minimize the cost function and to avoid high-computation costs. Synthetic modellings have shown that the algorithm can be successfully used to invert resistivity data collected on complex 3-D structures with a large number of data and model parameters. Introduction The finite element method has been used by several authors in the context of direct current electrical resistivity inverse modelling.
-
-
-
Modeling and Monitoring the Tortin Alpine Glacier by Gravity and DGPS Surveys
Authors P. Chassseriau, P. Radogna, P. Logean, V. Lattion and R. OlivierA031 Modeling and monitoring the Tortin alpine glacier by gravity and DGPS surveys 1 Pierrick CHASSERIAU PierVittorio RADOGNA Philippe LOGEAN Vincent LATTION and Raymond OLIVIER Institute of Geophysics. Geosciences & Environment Department. University of Lausanne. Switzerland Abstract Since many years a significant retreat of alpine glaciers is observed. Some of them located in tourist areas have a special interest for ski resorts facilities. That is the case of the 3000 meters high Tortin glacier located on north face of Mont Fort in the Valais state (Switzerland). Several surveys (gravimetry DGPS Georadar) have been carried out in the last years (2001-2005).
-
-
-
Automatic Determination of Dispersion Curves
Authors B. Neducza and L. HermannA032 Automatic determination of dispersion curves Introduction 1 The well known and widely used Spectral Analysis of Surface Waves (SASW) and Multi- Channel Analysis of Surface Waves (MASW) methods of shear wave velocity (Vs) determination have crucial steps. One of these important points is the accurate determination of the dispersion data of Rayleigh waves because obviously these data influence the results of all further processing steps. In the classical SASW the method of determining dispersion data is the cross-power spectrum of surface waves received by two geophones. Although the proper distance of the geophone pair provides good horizontal resolution the
-
-
-
Geostatistical Estimation of Structural Vulnerability
Authors A.V. Christiansen, E. Auken, K. Sørensen, F. Jørgensen and R. JohnsenA033 Geostatistical estimation of structural vulnerability Summary 1 In this abstract we present a newly developed concept using geostatistical estimation and nonlinear inversion to optimize a function translating geophysical resistivity models to geophysical clay thickness. The algorithm uses information on reported clay thicknesses in drill holes. We call it geoStatistical estimation of Structural Vulnerability (SSV). The clay thickness in the upper part of the subsurface is an important factor for the water infiltration speed and thereby the vulnerability of underlying aquifers to pesticides nitrate etc. Drill hole information contains the most detailed information on clay thicknesses but most often drill
-
-
-
Characterization of Fractured Rock Aquifers by Surface Geophysical Methods
Authors A. Legchenko, M. Descloitres, L. Ruiz, M. Reddy, J.-F. Girard and M. SekharA034 Z-99 Characterization of fractured rock aquifers by surface geophysical methods Summary Comparison of MRS results with static water level measurements and hydraulic conductivity estimation in boreholes shows that MRS method could be an efficient tool for investigation of weathered part of crystalline aquifers with the effective porosity greater than 1%. It was shown using both numerical modeling and field measurements that the MRS method allows characterizing two- dimensional subsurface formations. Presented field example proves that a combination of the MRS with 2D electrical imaging tool improves geophysical results in complex heterogeneous gneissic formations of Southern India. Introduction Magnetic Resonance
-
-
-
Monitoring Water Content in the Porous Medium with 4-D GPR – Physical Model Experiment
Authors C. Kim and J.J. DanielsA035 Monitoring Water Content in the Porous Medium with 4-D GPR: Physical Model Experiment Abstract 1 A physical model experiment using a sand and gravel-filled tank was conducted to investigate the response of Ground Penetrating Radar (GPR) over simulated hydrogeologic conditions. Repeated GPR measurements were made on a 3-D survey grid on the surface of the tank at each level of water table for an extended period of time during raising and lowering the water table in stages to monitor changes in the sand and gravel layers in the tank. The results of the experiment during fluctuating water table demonstrate
-
-
-
Numerical Modelling of Ground Penetrating Radar Antennas
More LessA036 NUMERICAL MODELLING OF GROUND PENETRATING RADAR ANTENNAS Introduction 1 Numerical modelling of ground penetrating radar (GPR) can significantly enhance our understanding of the GPR’s detection mechanism especially in complex environments. In addition models could aid GPR data interpretation. There are a number of numerical methods that can be used to develop a forward GPR model. One of the most versatile and powerful technique is the Finite-Difference Time-Domain (FDTD) method pioneered by Kane Yee (1966). FDTD has been used successfully to model GPR responses from simple targets assuming either a two dimensional or a three dimensional geometries (Holliger et. al.
-
-
-
Use of Acoustic Method to Study Rock Mass in Tunnel Engineering
Authors A. Antsiferov, M. Tirkel, A. Glukhov and V. AntsiferovA037 Use of acoustic method to study rock mass in tunnel engineering 1 A. ANTSIFEROV M. TIRKEL A. GLUKHOV V. ANTSIFEROV UkrNIMI NANU 291 Chelyuskintsev St. 83121 Donetsk Ukraine Abstract In this article procedure for acoustic prediction of structural-tectonic structure of rock mass is given through a case history of engineering survey in construction of the tunnel through the Markotkhsky ridge (Krasnodarsky krai Russia). Introduction Many underground structures require engineering-geological research at all stages of design and construction. Conducting of research is of special significance in tunnel engineering. Tunnels are both difficult for construction and maintenance and also expensive and
-
-
-
Advances in Surface Wave Methods – Cascaded MASW-SASW
Authors R.S. Westerhoff, J.H. Brouwer and J.A.C. MeekesA038 Advances in surface wave methods: cascaded MASW-SASW Abstract 1 The application of the MASW method in areas that show strong lateral variations in subsurface properties is limited. Traditional SASW may yield a better lateral resolution but the dispersion curves (and thus the subsurface models) obtained with the method may be poor. The joint application of MASW and SASW is proposed to allow for a robust determination of dispersion curves and the incorporation of lateral changes in subsurface properties. The method involves the application of MASW for the initial estimation of a gross dispersion curve. From the gross dispersion curve
-
-
-
Time-Lapse Shear-Wave Seismic to Define the Lateral Extent of Impact Due to Sheet Piling
By R. GhoseA039 Z-99 Time-lapse shear-wave seismic to define the lateral extent of impact due to sheet piling Summary 1 It has not been possible so far to measure in the field in a laterally continuous manner the impact of sheet piling on subsoil structures and hence potentially on adjacent buildings. We propose the idea of time-lapse shear-wave seismic reflection surveys for this purpose. Result on field data shows that despite the usual difficulty to achieve sufficient reproducibility in seismic field data acquisition the impact of sheet piling on the soil boundaries can still be distinctly recognized in the time-lapse shearwave data.
-
-
-
Seismic Reconnaissance beyond the Faces of an Advancing Coal Mine Roadway
Authors K. Essen, R. Misiek and W. FriederichA040 SEISMIC RECONNAISSANCE BEYOND THE FACES OF AN ADVANCING COAL MINE ROADWAY K. ESSEN 1 R. MISIEK 1 AND W. FRIEDERICH 2 Summary 1 Within the scope of the current project the aim is to develop a non-destructive investigation technique using seismic waves to obtain information on the state of the rock ahead of the faces of a coal mine roadway. First test measurements were carried out in a mine of the Deutsche Steinkohle AG (DSK) in the northern Ruhr area. A series of disturbances are expected beyond the faces of this roadway from geologic investigations. Synthetic seismograms were calculated
-
-
-
Use of Surface Waves for Geotechnical Characterization of Neogene Deposits–The Glyfada, Athens Case Study
Authors K. Symeonidis, T.D. Papadopoulos and J. AlexopoulosA041 Z-99 Use of surface waves for geotechnical characterization of 1 neogene deposits – The Glyfada Athens case study. AUTHORS K. Symeonidis T.D. Papadopoulos and J. Alexopoulos University of Athens Geophysics-Geothermics Dpt. Panepistimiopolis Zographou 15784 Athens Greece Abstract Summary. The surface waves method was used in this case study as an alternative and efficient tool for geological and geotechnical investigation. The site is located at Glyfada Athens where neogene formations mainly composed by clayish layers with intercalations of conglomerates are present. The results were compared with data from geotechnical investigation and seismic refraction data. Introduction. The test site is located
-
-
-
Assessment of the Quality of Radar Results on Bridge Decks
More LessA042 Z-99 Assessment of the quality of radar results on Abstract Summary 1 bridge decks JOHANNES HUGENSCHMIDT EMPA Ueberlandstrasse 129 8600 Dübendorf Switzerland [email protected] Ground-Penetrating-Radar has become an important tool for non-destructive testing of concrete bridges. The evalution of the quality of radar results is in most cases restricted to very few points on real objects or to laboratory experiments. In recent years Empa had the opportunity to complete several projects aiming at the evaluation of radar results on concrete bridges. This paper presents an overview of the results giving a quantitative estimate of the quality of radar results. Introduction
-
-
-
Assets and Drawbacks of Draped Airborne-Magnetic Surveys in Highly Magnetized Regions – A Case Study
Authors C. Stotter and R. SupperA043 ASSETS AND DRAWBACKS OF DRAPED AIRBORNE-MAGNETIC SURVEYS IN HIGHLY MAGNETIZED REGIONS – A CASE STUDY Summary 1 High resolution draped airborne magnetic surveys are ideal for the collection of huge amounts of data in a relatively short time especially in areas that are not directly accessible from the ground like young volcanic morphologies. Technological developments have steadily increased the precision and consequently the possibilities of the airborne magnetic method. This however demands a corresponding increase of the accuracy of processing and of positioning especially in highly magnetized areas. Furthermore some of the basic assumptions of potential field methods (in
-
-
-
Airborne Geophysical Surveys Applied to Urban/Brownfield Investigations
Authors D. Beamish, R.J. Cuss and E. TartarasA044 Z-99 AIRBORNE GEOPHYSICAL SURVEYS APPLIED TO URBAN/BROWNFIELD INVESTIGATIONS 1 Abstract A number of airborne geophysical surveys have now been conducted in the UK using a fixedwing system operated jointly by the British and Finnish Geological Surveys. The system provides magnetic radiometric and frequency domain electromagnetic survey measurements. Regulatory survey permissions force a variety of flight elevations typically between 54 to 244 m. On the fringes of major conurbations we encounter urban greenspace and brownfield areas. These areas may contain mixtures of infrastructure and built structures together with derelict and green areas. In order to provide valid interpretations of the
-
-
-
Geophysics Applied in Tunnel Pilot Boreholes for Pre-Grouting Design Parameters
Authors E. Heikkinen, M. Lahti, E. Tammisto, H. Ahokas and T. AhokasA045 GEOPHYSICS APPLIED IN TUNNEL PILOT BOREHOLES FOR PRE-GROUTING DESIGN PARAMETERS Abstract 1 Geophysical logging was used in two pilot boreholes of an access tunnel to underground nuclear waste storage to provide design information for pre-grouting and support. Boreholes were diamond drilled from ground surface and tunnel. The surveys in first borehole were used to design the works and the advised methods were applied in the second pilot borehole drilled during tunnel excavation within a period of three days after which the excavation continued immediately and was interrupted over minimal time period. Logging methods were optical imaging flow logging borehole
-