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Geofysiska mätmetoder för prospektering till ballastmaterial

Bohlin, Erik and Landen, Ludvig (2008) In Examensarbeten i geologi vid Lunds universitet
Department of Geology
Abstract
The Swedish rock-mass industry is currently in a transition period because new rules and regulations strongly limit the possibility to use naturally sorted aggregates for construction and concrete purposes. Furthermore, research and development within the industry is more oriented towards crushed bedrock aggregates. Whilst the crystalline bedrock of Scandinavia mostly consists of Precambrian gneiss that has been de¬formed a great number of times for over one billion ye¬ars, the quality of the bedrock varies rigorously within small areas. This report aims at creating an instrument to visualize the subsurface, by using near surface geop¬hysics, and connect collected data with variations in the quality of what will be aggregates for... (More)
The Swedish rock-mass industry is currently in a transition period because new rules and regulations strongly limit the possibility to use naturally sorted aggregates for construction and concrete purposes. Furthermore, research and development within the industry is more oriented towards crushed bedrock aggregates. Whilst the crystalline bedrock of Scandinavia mostly consists of Precambrian gneiss that has been de¬formed a great number of times for over one billion ye¬ars, the quality of the bedrock varies rigorously within small areas. This report aims at creating an instrument to visualize the subsurface, by using near surface geop¬hysics, and connect collected data with variations in the quality of what will be aggregates for construction purposes. This survey has been performed at three different quarries, all of which differ from a geologic perspec¬tive.

The electric method used was continuous vertical electrical sounding (CVES) where resistivity and IP-data were collected. 11 parallel profiles were performed with an equal distance of 4 meters and a length of 160 meters for all three sites where the survey was performed. The data collected were inverted both as two-dimensional pro¬files and a three-dimensional grid. A seismic profile was also performed at each site. The profile was 166 meters and was placed along one CVES-profile of special interest. Along the profile there were 39 shoots and the source of energy was a shotgun. Two 24-channel seis¬mographs were used for maximum data coverage. As electromagnetic method, magnetometry was chosen. The measurements were only perfor¬med in two of the sites because no significant magnetic anomaly was expected at the third site.

The results of this report show that a combination of the near surface geophysical methods used in this sur¬vey can generate a good picture of the subsurface. The report also shows how joints and fracture zo¬nes, dykes, aggregates of clay and weak structures in the bedrock surface can be detected. The fracture frequency has also been interpreted and attempts were made to correlate the geophysical data with the standard mechanical tests for rock aggre¬gates. One conclusion of this report is that quarries can gain a lot by performing more geophysical surveys. (Less)
Abstract (Swedish)
Bergmaterialindustrin i Sverige befinner sig just nu i en omstruktureringsfas då nya regler starkt
begränsar möjligheten att använda sig av naturgrus för så väl bygg- och anläggningsändamål som för betongindustrin.
Detta har även lett till att teknikutvecklingen stävar mot en övergång mot krossat berg, och inte sällan har det
lett till bergmaterial med egenskaper som överträffar dem för naturgrus. Då Skandinaviens berggrund till stor del
består av prekambrisk kristallin gnejs som utsatts för upprepad deformation under ett par tusen miljoner år varierar
kvaliteten, med hänseende på de mekaniska egenskaperna, i krossat bergmaterial ofta stort inom små områden.
Denna studie syftar till att med hjälp av marknära geofysiska... (More)
Bergmaterialindustrin i Sverige befinner sig just nu i en omstruktureringsfas då nya regler starkt
begränsar möjligheten att använda sig av naturgrus för så väl bygg- och anläggningsändamål som för betongindustrin.
Detta har även lett till att teknikutvecklingen stävar mot en övergång mot krossat berg, och inte sällan har det
lett till bergmaterial med egenskaper som överträffar dem för naturgrus. Då Skandinaviens berggrund till stor del
består av prekambrisk kristallin gnejs som utsatts för upprepad deformation under ett par tusen miljoner år varierar
kvaliteten, med hänseende på de mekaniska egenskaperna, i krossat bergmaterial ofta stort inom små områden.
Denna studie syftar till att med hjälp av marknära geofysiska undersökningsmetoder skapa ett instrument för att
i större utsträckning kunna visualisera dels berggrundens överyta, dels att försöka koppla samman data som metoderna
genererar till variationer i kvaliteten som berggrunden besitter. Undersökningarna genomfördes vid tre olika
stenbrott, som alla skiljer sig från varandra ur ett geologiskt perspektiv.
Som elektrisk undersökningsmetod användes multi-elektrodmätning, så kallad CVES (Countinous Vertical
Electrical Sounding), där resistivitets- och IP-data samlades in. Elva parallella profiler utfördes med 4 meters inbördes
avstånd och 160 meters längd för vart och ett av de tre stenbrotten. De data som erhölls inverterades både som
tvådimensionella profiler och som en tredimensionell kropp. En seismisk profil utfördes per undersökningslokal.
Profilen var 166 meter lång och drogs längs en utvald CVES-profil. Längs profilen gjordes 39 skottpunkter med
”shotgun” som energikälla. Två stycken seismografer användes med vardera 24 geofoner för att samla in data. Som
elektromagnetisk metod användes magnetometri. Magnetometrimätningarna utfördes endast på två av undersökningslokaliteterna
då den tredje inte förväntades uppvisa någon större magnetisk anomali. En lokalitet gav användbar
data.
Resultaten visar att en kombination av de använda geofysiska undersökningsmetoderna kan ge en god bild av
markens underyta. Rapporten visar bland annat hur man kan detektera sprickzoner, gångbergarter, leransamlingar
och svaghetszoner samt den kristallina bergrundens överytan. Även berggrundens sprickfrekvens har kunnat uppskattas.
Försök har även gjorts att direkt korrelera geofysisk data med mekaniska kvalitetstester. En slutsats av vikt i
rapporten är att särskilt vid större bergtäkter finns mycket att vinna på en ökad användning av geofysisk undersökningsmetodik. (Less)
Please use this url to cite or link to this publication:
author
Bohlin, Erik and Landen, Ludvig
supervisor
organization
alternative title
Geophysical methods used for aggregate prospecting
year
type
H1 - Master's Degree (One Year)
subject
keywords
prospektering, ballastmaterial, LosAngeles test, microDeval test, kulkvarnstest, resistivitet, IP, normaliserad IP, refraktionseismik, tomografi, geofysik, geologi, aggregate prospecting, electrical resistivity imaging, induced polarization, normalized induced polarization, refraction seismics, tomography, studded tyres test, geophysics, geology
publication/series
Examensarbeten i geologi vid Lunds universitet
report number
236
language
Swedish
additional info
Mimmi Magnusson, Kungliga tekniska högskolan, KTH.
id
2303183
date added to LUP
2012-03-20 09:05:04
date last changed
2012-03-20 09:05:04
@misc{2303183,
  abstract     = {The Swedish rock-mass industry is currently in a transition period because new rules and regulations strongly limit the possibility to use naturally sorted aggregates for construction and concrete purposes. Furthermore, research and development within the industry is more oriented towards crushed bedrock aggregates. Whilst the crystalline bedrock of Scandinavia mostly consists of Precambrian gneiss that has been de¬formed a great number of times for over one billion ye¬ars, the quality of the bedrock varies rigorously within small areas. This report aims at creating an instrument to visualize the subsurface, by using near surface geop¬hysics, and connect collected data with variations in the quality of what will be aggregates for construction purposes. This survey has been performed at three different quarries, all of which differ from a geologic perspec¬tive. 

The electric method used was continuous vertical electrical sounding (CVES) where resistivity and IP-data were collected. 11 parallel profiles were performed with an equal distance of 4 meters and a length of 160 meters for all three sites where the survey was performed. The data collected were inverted both as two-dimensional pro¬files and a three-dimensional grid. A seismic profile was also performed at each site. The profile was 166 meters and was placed along one CVES-profile of special interest. Along the profile there were 39 shoots and the source of energy was a shotgun. Two 24-channel seis¬mographs were used for maximum data coverage. As electromagnetic method, magnetometry was chosen. The measurements were only perfor¬med in two of the sites because no significant magnetic anomaly was expected at the third site.

The results of this report show that a combination of the near surface geophysical methods used in this sur¬vey can generate a good picture of the subsurface. The report also shows how joints and fracture zo¬nes, dykes, aggregates of clay and weak structures in the bedrock surface can be detected. The fracture frequency has also been interpreted and attempts were made to correlate the geophysical data with the standard mechanical tests for rock aggre¬gates. One conclusion of this report is that quarries can gain a lot by performing more geophysical surveys.},
  author       = {Bohlin, Erik and Landen, Ludvig},
  keyword      = {prospektering,ballastmaterial,LosAngeles test,microDeval test,kulkvarnstest,resistivitet,IP,normaliserad IP,refraktionseismik,tomografi,geofysik,geologi,aggregate prospecting,electrical resistivity imaging,induced polarization,normalized induced polarization,refraction seismics,tomography,studded tyres test,geophysics,geology},
  language     = {swe},
  note         = {Student Paper},
  series       = {Examensarbeten i geologi vid Lunds universitet},
  title        = {Geofysiska mätmetoder för prospektering till ballastmaterial},
  year         = {2008},
}