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Resistivity and IP measurements at the Bolmen Tunnel and Ådalsbanan, Sweden

Cegrell, Miriam and Mårtensson, Jimmy (2008) In Dissertations in Geology at Lund University
Department of Geology
Abstract
In all tunnel construction projects geophysical methods are important as a foundation for engineering
geological conceptual models. Detailed information about the condition and the physical properties of rocks at
depth is desirable, and geophysical methods have the potential to exploit these properties. This work is based on
geophysical investigations with focus on the geoelectrical methods. The methods are direct current (DC) resistivity
and induced polarisation (IP). The use of the continuous vertical electrical sounding (CVES) gives continuous data
in a time and cost efficient way. The methods have been tested at two tunnel investigation sites in Sweden, at the
Bolmen tunnel and Ådalsbanan. Complementary magnetic and VLF (Very Low... (More)
In all tunnel construction projects geophysical methods are important as a foundation for engineering
geological conceptual models. Detailed information about the condition and the physical properties of rocks at
depth is desirable, and geophysical methods have the potential to exploit these properties. This work is based on
geophysical investigations with focus on the geoelectrical methods. The methods are direct current (DC) resistivity
and induced polarisation (IP). The use of the continuous vertical electrical sounding (CVES) gives continuous data
in a time and cost efficient way. The methods have been tested at two tunnel investigation sites in Sweden, at the
Bolmen tunnel and Ådalsbanan. Complementary magnetic and VLF (Very Low Frequency) measurements has also
been carried out. Pre-investigations of tunnelling construction projects commonly include core drilling. The resistivity
and IP methods provide significant geological information and by including these methods at an initial stage,
the selection of drilling site can be optimized. By combining different geophysical methods with drilling a more
reliable model can be compiled. The resistivity method is based on the fact that each rock has a specific physical
character. The physical property of the rock can then be interpreted in terms of geological properties and in some
cases even allow an assessment of the rock mass quality. The main purpose in this work was to estimate the applicability
and the limitations of these methods used for pre-investigation in tunnel construction projects. This material
includes geological interpretations and estimations of the quality of the rock based on geoelectrical methods.
With the resistivity method several low resistive zones were detected and interpreted as weakness zones. Many of
these were verified by data from earlier tunnel investigations. The IP method gave information about the character
(e.g. water and clay content) of the fracture zones and served as a complement to the resistivity method. These
methods provided general information, from which a geological model was estimated. The results show that the
resistivity and IP are useful methods in pre-investigation for sub-surface tunnel constructions. (Less)
Abstract (Swedish)
Geofysiska metoder används vid alla tunnelbyggnadsprojekt då geotekniska beskrivningar och
modeller baseras på resultat från dessa. Detaljerade redogörelser för markförhållanden och information om djupet
till berggrunden är av intresse, och med geofysiska metoder kan dessa parametrar utvärderas. Detta arbete är baserat
på geofysiska undersökningar med fokus på de geoelektriska metoderna. Metoderna som använts är DC (direct
current) resistivitet och inducerad polarisation (Induced Polarisation, IP). CVES (Continous Vertical Electrical
Sounding) är en kostnads- och tidseffektiv resistivitets-metod som ger kontinuerlig data. Dessa metoder har testats
på undersökningsområden belägna ovanför två tunnlar i Sverige, Bolmentunneln och... (More)
Geofysiska metoder används vid alla tunnelbyggnadsprojekt då geotekniska beskrivningar och
modeller baseras på resultat från dessa. Detaljerade redogörelser för markförhållanden och information om djupet
till berggrunden är av intresse, och med geofysiska metoder kan dessa parametrar utvärderas. Detta arbete är baserat
på geofysiska undersökningar med fokus på de geoelektriska metoderna. Metoderna som använts är DC (direct
current) resistivitet och inducerad polarisation (Induced Polarisation, IP). CVES (Continous Vertical Electrical
Sounding) är en kostnads- och tidseffektiv resistivitets-metod som ger kontinuerlig data. Dessa metoder har testats
på undersökningsområden belägna ovanför två tunnlar i Sverige, Bolmentunneln och Ådalsbanan.
Komplimenterande mätningar med VLF (Very Low Frequency) och magnetometer har även utförts. Förundersökningarna
till tunnelprojekt innefattar ofta kärnborrning. Resistivitet och IP metoden ger viktig geologisk information
och genom att i ett tidigt skede inkludera dessa metoder, kan en bedömning av det mest optimala läget för
borrningen göras. Användandet av flera geofysiska metoder tillsammans med borrningar, ökar tillförlitligheten i
den framtagna modell som visar markens uppbyggnad. Resistivitetsmetoden bygger på att man kan särskilja olika
bergarter då deras fysiska egenskaper skiljer sig. En bergarts fysiska egenskaper kan kopplas till dess geologiska
karaktär och i vissa fall kan även en bedömning av bergets kvalitet göras. Syftet med denna studie har varit att utvärdera
metodernas användbarhet och eventuella begränsningar i samband med förundersökningar till tunnelprojekt.
Detta arbete innefattar geologiska tolkningar och utvärderingar av bergkvalitén som baserats på resultaten
från de geoelektriska metoderna. Med resistivitetsmetoden detekterades flera lågresistiva zoner som tolkades som
svaghetszoner. Förekomsten av flertalet svaghetszoner kunde verifieras av data från tidigare tunnelundersökningar.
IP-metoden gav information om sprickzonernas karaktär (såsom förekomst av vittring och lerinnehåll) och har i
detta arbete fungerat som ett komplement till resistivitetsmetoden. Dessa metoder ger övergripande information om
geologin och utifrån denna kan en geologisk modell tas fram. Resultaten visar att resistivitets- och IP-metoden är
användbara metoder i förundersökningar för konstruktionsprojekt av bergtunnlar. (Less)
Please use this url to cite or link to this publication:
author
Cegrell, Miriam and Mårtensson, Jimmy
supervisor
organization
alternative title
Resistivitet och IP mätningar längs Bolmen tunneln och Ådalsbanan, Sverige
year
type
H1 - Master's Degree (One Year)
subject
keywords
resistivity, induced polarisation (IP), geophysics, geology, Bolmen, Ådalsbanan, resistivitet, inducerad polarisation (IP), geofysik, geologi
publication/series
Dissertations in Geology at Lund University
report number
231
language
English
id
2303826
date added to LUP
2012-01-30 11:02:07
date last changed
2012-01-30 11:02:07
@misc{2303826,
  abstract     = {In all tunnel construction projects geophysical methods are important as a foundation for engineering
geological conceptual models. Detailed information about the condition and the physical properties of rocks at
depth is desirable, and geophysical methods have the potential to exploit these properties. This work is based on
geophysical investigations with focus on the geoelectrical methods. The methods are direct current (DC) resistivity
and induced polarisation (IP). The use of the continuous vertical electrical sounding (CVES) gives continuous data
in a time and cost efficient way. The methods have been tested at two tunnel investigation sites in Sweden, at the
Bolmen tunnel and Ådalsbanan. Complementary magnetic and VLF (Very Low Frequency) measurements has also
been carried out. Pre-investigations of tunnelling construction projects commonly include core drilling. The resistivity
and IP methods provide significant geological information and by including these methods at an initial stage,
the selection of drilling site can be optimized. By combining different geophysical methods with drilling a more
reliable model can be compiled. The resistivity method is based on the fact that each rock has a specific physical
character. The physical property of the rock can then be interpreted in terms of geological properties and in some
cases even allow an assessment of the rock mass quality. The main purpose in this work was to estimate the applicability
and the limitations of these methods used for pre-investigation in tunnel construction projects. This material
includes geological interpretations and estimations of the quality of the rock based on geoelectrical methods.
With the resistivity method several low resistive zones were detected and interpreted as weakness zones. Many of
these were verified by data from earlier tunnel investigations. The IP method gave information about the character
(e.g. water and clay content) of the fracture zones and served as a complement to the resistivity method. These
methods provided general information, from which a geological model was estimated. The results show that the
resistivity and IP are useful methods in pre-investigation for sub-surface tunnel constructions.},
  author       = {Cegrell, Miriam and Mårtensson, Jimmy},
  keyword      = {resistivity,induced polarisation (IP),geophysics,geology,Bolmen,Ådalsbanan,resistivitet,inducerad polarisation (IP),geofysik,geologi},
  language     = {eng},
  note         = {Student Paper},
  series       = {Dissertations in Geology at Lund University},
  title        = {Resistivity and IP measurements at the Bolmen Tunnel and Ådalsbanan, Sweden},
  year         = {2008},
}