Symposium on the Application of Geophysics to Engineering and Environmental Problems 2018最新文献

{"title":"REFRACTION SEISMIC MODELING AND INVERSION FOR THE DETECTION OF FRACTURE ZONES IN BEDROCK","authors":"G. Tassis, J. Rønning, S. Rohdewald","doi":"10.4133/SAGEEP.31-036","DOIUrl":"https://doi.org/10.4133/SAGEEP.31-036","url":null,"abstract":"We have investigated the response of several synthetic models of variable complexity to tomographic inversion using Rayfract. This software is fairly advanced and complex and offers many different options when inverting refraction seismic data. Using this program to investigate the detection of fracture zones in bedrock, its parameters may be roughly grouped in three categories: the inversion and weighting method used, whether single or multi-run will be employed and the intensity of smoothing. We have discerned that multi-run Conjugate Gradient inversion method, with CosineSquared weighting and a 2D Plus-Minus starting model can give fairly good results. Minimal smoothing is also essential for the quantitative characteristics of the detected zones to be accurately calculated, but this is a hyper sensitive procedure which may result in over or underestimations of zone velocity values. Generally, we have concluded that it possible to locate and characterize fractured zones in bedrock albeit with some limitations. It has been found that the imaging of the position and inclination of zones can be problematic especially when the zones are neighboring bedrock areas with small velocity contrast. The detectable depth extent of fracture zones can be followed to a certain depth, but deep zones give the same response as shallow zones due to geological noise. The width of the zone is almost always very accurate and overburden layers can be precisely defined when the interactive picking of branch points prior to inversion is carefully done. The velocity of a zone can be calculated with a good combination of inversion parameters. Moreover, as seen after reprocessing some of the Knappe tunnel data, tomographic inversion can pick up zones that cannot be interpreted traditionally. Finally, denser shot point spacing can bring about a noticeable improvement on the inversion results.","PeriodicalId":156801,"journal":{"name":"Symposium on the Application of Geophysics to Engineering and Environmental Problems 2018","volume":"183 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-10-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121946779","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"3D TIME-LAPSE GEOELECTRICAL MONITORING OF MOISTURE CONTENT IN AN EXPERIMENTAL WASTE ROCK PILE: VALIDATION USING HYDROGEOLOGICAL DATA","authors":"Adrien Dimech, M. Chouteau, V. Martin, M. Aubertin, B. Bussière, B. Plante","doi":"10.4133/SAGEEP.31-009","DOIUrl":"https://doi.org/10.4133/SAGEEP.31-009","url":null,"abstract":"The hydrogeological behavior of heterogeneous and unsaturated media can be challenging to assess, especially where classical hydrogeological instrumentation cannot be directly installed such as in the core of waste rock piles. In this paper, the authors present the results of several 3D Electrical Resistivity Tomography surveys carried out in 2017 for time-lapse monitoring of water infiltration events in an experimental waste rock pile. This pile was built according to a recently proposed waste rock disposal method at the Lac Tio mine (RTFT, Québec, CA) that aims at diverting water flow from potentially reactive waste rock, thus limiting metal leaching and contamination of the effluent. The pile has been instrumented with soil moisture sensors and lysimeters to monitor water content over time and collect percolating water. In addition, 192 buried electrodes have been used to carry hourly measurements with an optimized protocol of 1000 configurations uploaded on a Terrameter LS (ABEM) to monitor internal flow of water sprinkled on the top of the pile with a water truck. Time-lapse 3D ERT data were inverted to yield the 3D model of soil electrical resistivity over time before, during and after induced infiltration events in the pile. While resistivity results show consistent variations associated with increased moisture content, conversion of resistivity into volumetric water content is not straightforward. This challenge is related, in part, to changes in the distribution of water resistivity over time in the pile, which in turn strongly affects resistivity within the waste rock. Laboratory column measurements have been conducted to assess the relationship between global (waste rock) resistivity, water resistivity and moisture content for samples from the pile. The images of water content obtained with ERT are then validated with hydrogeological measurements and modeling of the pile. This assessment indicates that geoelectrical monitoring is an efficient tool to monitor water moisture in a complex media.","PeriodicalId":156801,"journal":{"name":"Symposium on the Application of Geophysics to Engineering and Environmental Problems 2018","volume":"44 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-10-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121962229","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"INFLUENCE OF GROUND INHOMOGENEITY ON WIND INDUCED GROUND VIBRATIONS","authors":"M. Mohammadi, C. Hickey, R. Raspet, V. Naderyan","doi":"10.4133/SAGEEP.31-029","DOIUrl":"https://doi.org/10.4133/SAGEEP.31-029","url":null,"abstract":"The mechanical behavior of the near surface of the ground (vadose zone, critical zone) is required for many geotechnical applications such as roadway construction, trafficability, foundation design, and agricultural production. The mechanical behavior may also be indirectly related to transport across this critical interface such as; water infiltration and gas flux which are important to hydrological and climate studies. Mechanical sources for investigating near surface of the ground included high frequency electromechanical sources and loudspeakers. We attempt to exploit the pressure fluctuations produced by wind as a source for investigating near surface soil properties. In a previous study, the ground was modeled as an elastic homogenous half space and a prediction model was developed for the wind-induced ground motion. However, ground is a layered or inhomogeneous medium and will have a different response due to the surface pressure. In this presentation, we discuss different kinds of theoretical inhomogeneous grounds and their available analytical responses due to a surface load. Furthermore, we use Comsol-Multiphysics®, a commercial finite element package, to simulate a more realistic ground consisting of a layer over a half-space. A new response function is derived by interpolating the Comsol output to substitute in the wind-ground coupling equations. A comparison between the homogeneous and non-homogeneous ground predictions are used to evaluate the importance of layering on wind-induced ground vibrations.","PeriodicalId":156801,"journal":{"name":"Symposium on the Application of Geophysics to Engineering and Environmental Problems 2018","volume":"18 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-10-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127046539","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"INTEGRATED GEOPHYSICAL INVESTIGATION OF IJEBU-IMERI ARCHEOLOGICAL SITE, SOUTH WESTERN NIGERIA","authors":"Blessing S. Ekpebabor, M. Oladunjoye, A. O. Opadeji","doi":"10.4133/SAGEEP.31-003","DOIUrl":"https://doi.org/10.4133/SAGEEP.31-003","url":null,"abstract":"Integrated geophysical investigations involving ground magnetic and electrical resistivity methods were conducted at Ijebu-Imeri archeological site, Ogun state, Southwestern Nigeria. The site served as a location for fabrication of tools used for construction of Sungbo Eredo for defensive purpose 600 years ago. The surveys were aimed at locating, determining the spatial distribution and depth of burial of artifacts, thereby reducing wild-cats excavation. Magnetic data were acquired using proton precession magnetometer while resistivity data were acquired using the Campus Ohmega resistivity meter. The magnetic survey comprises thirty-one profiles in N-S and E-W directions with station interval of 5 m and inter-profile spacing of 5 m while the electrical survey comprises five parallel and four perpendicular profiles selected based on result of magnetic data. Wenner configuration with electrode spacing ranging from 1.0 – 6.0 m was employed for 2D electrical resistivity tomography. Profile length ranges from 1.0 100 m in the E-W direction and 0 – 68 m in the N-S direction for both methods. The magnetic data were processed and analyzed using Oasis Montaj Geosoft software while the resistivity data were processed and analyze using DIPRO for Windows software. Results of processed data were integrated and it revealed a distribution of the buried archaeological features within the study area. From the magnetic maps, regions of magnetic highs correspond to those of high resistivity on the 2D subsurface structure models. It was concluded that the areas with high magnetic and resistivity anomalies are possible areas that has buried artifacts with depths ranging 0 2 m. Trial pits located at regions of high total magnetic intensity and model resistivity yielded burnt pipes (TUYERE), iron slag; pottery fragments (POTSHERDS) and charcoal occurring at 0 – 0.6 m. The geophysical results therefore provided reliable and useful guide in pre-excavation of archaeology materials.","PeriodicalId":156801,"journal":{"name":"Symposium on the Application of Geophysics to Engineering and Environmental Problems 2018","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-10-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"134135132","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"GEOPHYSICAL AND PERMEABILITY ASSESSMENT OF SOIL SPATIAL VARIABILITY OF COCOA RESEARCH FARM IBADAN, SOUTHWESTERN NIGERIA","authors":"A. A. Olaojo, M. Oladunjoye, A. O. Oyerinde","doi":"10.4133/SAGEEP.31-031","DOIUrl":"https://doi.org/10.4133/SAGEEP.31-031","url":null,"abstract":"Site specific management has been the recent trend in assessing agricultural soil quality to optimizing productivity. This research stemmed from variations observed in pods yield by cocoa trees at Cocoa Research Institute of Nigeria. Soil conductivity (EC), volumetric water content (VWC), thermal properties and soil permeability were assessed at the root zone (0.3 m) to delineate soil’s management areas within cocoa farm. Spatial evaluations were conducted during the wet and dry seasons. A total of twenty-seven lines were occupied consisting of 912 and 906 EC/VWC data points during wet and dry seasons respectively on a non-saline soil (˂2000 μS/cm) using Allied resistivity earth meter (EC) and VG-meter-200 soil moisture meter (VWC). KD2PRO was used in evaluating the thermal regime during wet (90 data points) and dry (89 data points) seasons; and permeability test conducted on ten soil samples. ECa map was generated using ARCGIS software classified the soil into zones of low, medium and high EC. Variation in VWC is synonymous to EC distribution in soils. Strong correlation of 0.971 (wet season) and 0.806 (dry season) existed between EC and VWC. Regions of high EC/VWC were characterized by soils of low thermal diffusivity, high specific heat, high thermal conductivity and weak to moderate correlations were generated between these thermal properties and EC/VWC. Soil permeability (k) studies revealed that soils from high EC section have low permeability (0.000126 to 0.000431 cm/sec) suggesting slow/moderately slow/moderate infiltration rate classified to be silty sand/dirty sand while electrically less conductive soils were characterized with high permeability (0.000437-0.004109 cm/sec) indicating moderate to moderately rapid infiltration associated with nutrient leaching and water depletion, categorized as silty/dirty sand/sand/fine sand. These techniques mapped out zones of abundant pods yield to be sections of high EC/VWC, low k and vice versa.","PeriodicalId":156801,"journal":{"name":"Symposium on the Application of Geophysics to Engineering and Environmental Problems 2018","volume":"30 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-10-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121080468","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"GEOPHYSICAL INVESTIGATIONS IN THE SALSOVIA SUBMERGED, ARCHAEOLOGICAL SITE","authors":"A. Sorin","doi":"10.4133/sageep.31-004","DOIUrl":"https://doi.org/10.4133/sageep.31-004","url":null,"abstract":"","PeriodicalId":156801,"journal":{"name":"Symposium on the Application of Geophysics to Engineering and Environmental Problems 2018","volume":"19 3","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-10-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121108968","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"COMMUNICATION OF GEOPHYSICS IN UNDERGROUND INFRASTRUCTURE PROJECTS","authors":"M. Svensson, O. Friberg","doi":"10.4133/SAGEEP.31-032","DOIUrl":"https://doi.org/10.4133/SAGEEP.31-032","url":null,"abstract":"","PeriodicalId":156801,"journal":{"name":"Symposium on the Application of Geophysics to Engineering and Environmental Problems 2018","volume":"130 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-10-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121999778","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"PROJECTIONS ANALYSIS OF SURFACE WAVES (PASW) - DESCRIPTION OF THE METHOD AND CASE STUDIES","authors":"A. Konkov, A. Lebedev, S. Manakov","doi":"10.4133/SAGEEP.31-016","DOIUrl":"https://doi.org/10.4133/SAGEEP.31-016","url":null,"abstract":"This study is intended to describe the PASW method and the results of its application. This technique is based on both the analysis of the dispersion and frequency dependence of the Rayleigh wave ellipticity. Unlike for SASW / MASW (Spectral / Multichannel Analysis of Surface Waves), during carrying out the PASW method there is no need for a priori information on the pressure wave velocity (or, in other words, on the Poisson's ratio) of the underlying layers. Thus, this technology allows one to reconstruct the velocity profiles of two body waves. By analogy with the names of SASW / MASW, the method is named PASW (Projections Analysis of Surface Waves). The study will describe the features of the technology, its advantages and disadvantages. The PASW method has been successfully used to solve various model engineering problems. The accent will be made on two cases: measuring the variations in soil characteristics under controlled saturation with water, and studying the effects of liquefaction.","PeriodicalId":156801,"journal":{"name":"Symposium on the Application of Geophysics to Engineering and Environmental Problems 2018","volume":"21 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-10-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133133116","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"MAPPING SUBSURFACE IN KARST TERRAIN USING 2-D ELECTRICAL RESISTIVITY TOMOGRAPHY","authors":"K. J. Bansah, N. Anderson","doi":"10.4133/SAGEEP.31-011","DOIUrl":"https://doi.org/10.4133/SAGEEP.31-011","url":null,"abstract":"","PeriodicalId":156801,"journal":{"name":"Symposium on the Application of Geophysics to Engineering and Environmental Problems 2018","volume":"54 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-10-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114791821","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"PSEUDO THREE-DIMENSIONAL IMAGING OF CREEP FAILURE IN A HIGHWAY EMBANKMENT USING TWO-DIMENSIONAL ELECTRIC EARTH RESISTIVITY","authors":"R. Balikian, T. Larson","doi":"10.4133/SAGEEP.31-034","DOIUrl":"https://doi.org/10.4133/SAGEEP.31-034","url":null,"abstract":"In May 2017, we carried out an electrical resistivity tomography (ERT) survey of the downslope embankment of a state highway in central Illinois where creep failure has been observed for over 50 years. The fill is over 15 meters (~50 feet) at its deepest point and sits partially in an old stream bed. Water is currently conveyed through the channel in a box culvert underneath the embankment. The fill has been steadily creeping since initial construction and has caused severe damage to the highway above on several occasions. The purpose of this study was to image the failure associated with the subsurface creep in the fill and to identify the subsurface engineering works that may be interacting or moving with the creep. We surveyed 10 parallel ERT profiles using an ABEM Terrameter SAS 4000. Nine profiles were 80 meters long and one was 40 meters long, with 10 meter spacing between each profile. We used an inline dipole-dipole array with electrodes spaced 2 meters apart (with a minimum 'a' spacing of 2 meters and a maximum was 4 meters; the minimum 'n' value was 1 and the maximum was 8). These 10 profiles were processed using Geotomo’s Res2DInv software. Topographic corrections were made using GPS and elevation data collected the same day as the ERT survey. The data was interpolated between the survey lines using ArcScene to create a pseudo 3-dimensional model to identify key components of the slope creep. Several underground objects were identified, including metal and plastic drainage pipes, a chimney drain, the box culvert, and possible groundwater plumes from recent rainfall events. The failure surface associated with the creep was also identified, and mapped in three dimensions. Figure 1: Study Area in Context. Elevation contours show elevation before construction of the embankment around 1961 Source: ESRI, QGIS","PeriodicalId":156801,"journal":{"name":"Symposium on the Application of Geophysics to Engineering and Environmental Problems 2018","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-10-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131188830","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}