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- Volume 41, Issue 8, 2023
First Break - Volume 41, Issue 8, 2023
Volume 41, Issue 8, 2023
- Special Topic: Near Surface Geo & Mining
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3D Gpr Array Technology for Optimisation of Production Planning in Infrastructure Projects
Authors Jaana Gustafsson, Jonas Siikanen, Jesper Emilsson, Johan Friborg and Mike LangtonAbstractThis article will discuss the benefits of optimised production planning when installing new, and/or maintaining existing, buried infrastructure. Optimised production planning is cost effective and reduces risks for damages and accidents. To optimise production planning, all available information in an area of interest needs to be collected. This is traditionally achieved through the combined use of drawings, visual inspections, data collected with EM locators and GPR, and often also making test pits.
As of late, specific planning software using 3D GPR array data and other input has become the preferred choice for time effective and detailed production planning. GPR array investigations can often detect and map all existing buried assets in high detail, thus reducing project time. The article will show results from a project performed in Stockholm, Sweden, using MALÅ 3D GPR array technologies and the Terra Eye software platform.
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The Role of Ground Penetrating Radar (GPR) Surveying for Indoor Building Information Modelling (BIM)
Authors Hector R. Hinojosa, Daniel P. Bigman and Sean McConnelAbstractTraditionally, GPR surveys are performed outdoors to identify buried or embedded objects’ location, orientation, and depth. The objects of interest are commonly linear, planar, or volumetric features of engineering, archeological, geological, or environmental context and significance. Due to constant improvements in component electronics and powerful GPR software developments, GPR hardware and software are finding indoor applications in architecture, engineering, and construction projects of historic and modern buildings and industrial infrastructure. Particularly, insights from indoor GPR surveys can non-invasively identify the embedded object and provide a high-resolution characterisation of the material properties surrounding the object, such that the output is a digital model feeding a Building Information Modelling (BIM) database. We present case studies illustrating how indoor 2D and 3D GPR surveys create digital information for such databases.
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P- and S-wave Seismic Imaging of a Complex Aquifer System in Kurikka, Western Finland
AbstractThe Kurikka area in western Finland is an example of the complex groundwater system with an important connection to the fractured bedrock. The leaky confined aquifer system developed in the glacial sediments overlying the bedrock. Location, dimension, and connectivity of bedrock deformation zones constitute a big uncertainty in the 3D geological model. To image sediments and bedrock structures, we acquired 2D multicomponent seismic data using a nodal system and planted 3-C geophones as receivers and an electrically driven seismic vibrator (E-vib) operating in both the P- and S-wave mode as a source. Acquired 6-C data confirm the benefits and complementary nature of the P- and S-wave imaging in such conditions. Seismic interpretation was supported by the P-wave velocity models obtained from first-arrival tomography. Seismic data enabled us to map the bedrock surface with more details, determine the width of the bedrock fracture zones and the thickness of the weathered bedrock zone. New data also prove their utility in mapping glacial sediments, providing both the structural control and lithology distribution through the changes in P-wave velocity. We demonstrate that seismic data can be considered a great asset in 3D modelling of the buried valley’s aquifer system, reducing uncertainties introduced by conceptual models based on borehole data.
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Advances in Seismic Imaging of Quick Clays in Sweden
Authors Tatiana Pertuz, Myrto Papadopoulou and Alireza MalehmirAbstractQuick clays are special types of soils that can liquefy under excess pore-water pressure with relatively low intrinsic stresses, resulting in landslides. In an area prone to quick-clay landslides in Sweden, various geophysical methods have been performed to map the subsurface. However, due to the high conductivity of the near-surface materials, seismic methods have shown greater potential than other geophysical methods. To exemplify this, a 2D seismic profile is presented with a 1 m shot and receiver spacing, having the highest resolution data so far acquired at the site. A processing workflow is followed to obtain P- and S- wave sections and their velocity models. Three main reflections identified early from raw shot gathers, are imaged in the final seismic sections. Borehole logging data are used to correlate the deepest reflection with the bedrock, overlayed by two coarse-grained layers. Our findings show the site is characterised by extremely slow S-wave velocities, between 60–100 m/s, that are indicative of high-water content along with the presence of quick-clay materials suggesting that the site requires special attention for future risk mitigation of landslides.
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Permanent 3D Data Acquisition of Geotechnical Structures Using Web-Based Application of Terrestrial Lidar — Chances and Risks from an Engineering Geodetic Point of View
Authors Daniel Czerwonka-Schröder and Karsten ZimmermannSummaryAs part of the research project i2MON – ‘Integrated Impact MONitoring for the detection of ground and surface displacements caused by coal mining’ funded by HORIZON 2020 through the RFCS (Research Fund for Coal and Steel), the leading author, in collaboration with various European institutions, is working on the development of an integrated monitoring service for the identification and assessment of ground and slope movements associated with coalmining. The focus is on the correct integration (reliability, accuracy and integrity) of a long-range laser scanner into a continuous web-based monitoring system from an engineering geodetic point of view. The objective of this work is the development of an integrated monitoring service for the identification and evaluation of ground and slope movements in the context of coalmining, the prevention of natural hazards and protection of infrastructure. The focus is on the integration of a long-range laser scanner (1) into a continuous web-based monitoring system and (2) from an engineering geodetic point of view.
In the Vals Valley in Tyrol, a permanently installed RIEGL laser scanner was successfully operated and web-based in the area of a rockfall in the summer of 2020 and 2021. The data was visualised in near real-time on a monitoring platform. This paper will describe the practical benefits of this installation. In addition to the potential of automatic data acquisition, possibilities for multi-temporal analysis with regard to spatio-temporal changes will be discussed.
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An Unbiased Spiral Array for MASW Data Acquisition
By Koya SutoAbstractMASW surveys generally use linear arrays, and the result is posted at the centre of the geophone array. A question is asked whether there is any bias related to the source offset and direction relative to the linear array. This paper first examines the existence of the biases by a receiver array with variable source and a source array to different receiver locations.
A new pattern of geophone array is proposed to attempt to eliminate these biases. It is an omnidirectional, variable offset array with a spiral pattern. Geometrically, there is no uncertainty in the centre of the array. An experimental survey was carried out to compare this spiral array with a linear array centred at the same point. A record by the spiral array can be analysed using conventional MASW software which assumes constant geophone interval. The records are compared in both the time-distance and the frequency-phase velocity domains. The result demonstrates the spiral array delivers comparable dispersion image to the linear array and it assures a more confident array centre location.
The spiral array also indicates viability of a MASW array arranged two-dimensionally. This is also a step forward to a 3D MASW.
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Volumes & issues
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Volume 42 (2024)
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Volume 41 (2023)
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Volume 40 (2022)
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Volume 39 (2021)
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Volume 38 (2020)
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Volume 37 (2019)
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Volume 36 (2018)
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Volume 35 (2017)
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Volume 34 (2016)
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Volume 33 (2015)
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Volume 32 (2014)
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Volume 31 (2013)
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Volume 30 (2012)
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Volume 29 (2011)
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Volume 28 (2010)
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Volume 27 (2009)
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Volume 26 (2008)
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Volume 25 (2007)
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Volume 24 (2006)
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Volume 23 (2005)
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Volume 22 (2004)
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Volume 21 (2003)
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Volume 20 (2002)
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Volume 19 (2001)
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Volume 18 (2000)
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Volume 17 (1999)
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Volume 16 (1998)
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Volume 15 (1997)
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Volume 14 (1996)
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Volume 13 (1995)
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Volume 12 (1994)
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Volume 11 (1993)
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Volume 10 (1992)
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Volume 9 (1991)
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Volume 8 (1990)
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Volume 7 (1989)
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Volume 6 (1988)
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Volume 5 (1987)
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Volume 4 (1986)
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Volume 3 (1985)
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Volume 2 (1984)
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Volume 1 (1983)