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  • 1.
    Dehkordi, Seyed Emad
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Sustainable development, Environmental science and Engineering, Land and Water Resources Engineering. University of Western Ontario, Canada.
    Olofsson, Bo
    KTH, School of Architecture and the Built Environment (ABE), Sustainable development, Environmental science and Engineering, Land and Water Resources Engineering.
    Schincariol, Robert A.
    Effect of groundwater flow in vertical and horizontal fractures on borehole heat exchanger temperatures2015In: Bulletin of Engineering Geology and the Environment, ISSN 1435-9529, E-ISSN 1435-9537, Vol. 74, no 2, p. 479-491Article in journal (Refereed)
    Abstract [en]

    Vertical closed loop systems, also known as borehole heat exchangers (BHEs), are a popular way of extracting the ground source heat energy. Primary factors affecting the performance of BHEs are the thermal and hydrogeological properties of the subsurface. Groundwater flow is known to potentially influence heat transport and system performance. The effect of groundwater movement is more commonly studied under homogeneous conditions. However, in heterogeneous fractured rocks, BHEs are more common than horizontal or open loops due to lack of sufficient soil layers and productive aquifers. The finite-element modelling shows that fractures can play an important role in BHE functioning. Especially, vertical open fractures (≥1 mm) near the borehole (≤10 m) can have a considerable impact. Although increase in fracture aperture continuously affects the subsurface and BHE temperatures, the increase in its effect progressively lessens. Depending on the distance and aperture, one major fracture influencing the BHE operation performance can be identified; yet a larger number of fractures may govern heat transport (thermal plume outline) and thermal recovery. Individually, horizontal fractures may have less influence than vertical fractures. However, as the density of horizontal fractures increases, their impact can be major, exceeding that of fracture aperture. In particular, we propose that measurements of rock thermal properties be combined with fracture mapping, to better analyse the thermal response testing results and integrate the configuration of fractures in design and layout of the BHE(s). This is particularly valid for (vertical) fractures not intersecting with the borehole.

  • 2.
    Ghaderi, Abdolvahed
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Soil and Rock Mechanics.
    Abbaszadeh Shahri, Abbas
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Soil and Rock Mechanics. Islamic Azad Univ, Roudehen Branch, Fac Civil Engn, Tehran, Iran..
    Larsson, Stefan
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Soil and Rock Mechanics.
    An artificial neural network based model to predict spatial soil type distribution using piezocone penetration test data (CPTu)2019In: Bulletin of Engineering Geology and the Environment, ISSN 1435-9529, E-ISSN 1435-9537, Vol. 78, no 6, p. 4579-4588Article in journal (Refereed)
    Abstract [en]

    Soil types mapping and the spatial variation of soil classes are essential concerns in both geotechnical and geoenvironmental engineering. Because conventional soil mapping systems are time-consuming and costly, alternative quick and cheap but accurate methods need to be developed. In this paper, a new optimized multi-output generalized feed forward neural network (GFNN) structure using 58 piezocone penetration test points (CPTu) for producing a digital soil types map in the southwest of Sweden is developed. The introduced GFNN architecture is supported by a generalized shunting neuron (GSN) model computing unit to increase the capability of nonlinear boundaries of classified patterns. The comparison conducted between known soil type classification charts, CPTu interpreting procedures, and the outcomes of the GFNN model indicates acceptable accuracy in estimating complex soil types. The results show that the predictability of the GFNN system offers a valuable tool for the purpose of soil type pattern classifications and providing soil profiles.

  • 3.
    Magnusson, Mimmi K.
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Land and Water Resources Engineering, Engineering Geology and Geophysics.
    Fernlund, Joanne
    KTH, School of Architecture and the Built Environment (ABE), Land and Water Resources Engineering, Engineering Geology and Geophysics.
    Dahlin, Torleif
    Department of Engineering Geology, Lund University.
    Geoelectrical imaging in the interpretation of geological conditions affecting quarry operations2010In: Bulletin of Engineering Geology and the Environment, ISSN 1435-9529, E-ISSN 1435-9537, Vol. 69, no 3, p. 465-486Article in journal (Refereed)
    Abstract [en]

    Determination of the subsurface geology is very important for the rock quarry industry. This is primarily done by drilling and mapping of the surface geology. However in Sweden the bedrock is often completely covered by Quaternary sediments making the prediction of subsurface geology quite difficult. Incorrect prediction of the rock-mass quality can lead to economic problems for the quarry. By performing geophysical measurements a more complete understanding of the subsurface geology can be determined. This study shows that by doing 2D-parallel data sampling a 3D inversion of the dataset is possible, which greatly enhances the visualization of the subsurface. Furthermore the electrical resistivity technique together with the induced polarization method proved to be very efficient in detecting fracture frequency, identification of major fracture zones, and variations in rock-mass quality all of which can affect the aggregate quality. With this technique not only the rock-mass quality is determined but also the thickness of the overburden. Implementation of geophysics can be a valuable tool for the quarry industry, resulting in substantial economic benefits.

  • 4.
    Robison Fernlund, Joanne
    KTH, School of Architecture and the Built Environment (ABE), Land and Water Resources Engineering, Engineering Geology and Geophysics.
    Image analysis method for determining 3-D size distribution of coarse aggregates2005In: Bulletin of Engineering Geology and the Environment, ISSN 1435-9529, E-ISSN 1435-9537, Vol. 64, no 2, p. 159-166Article in journal (Refereed)
    Abstract [en]

    A new 3-D grain size distribution analysis method for coarse aggregates using image analysis is presented. The method is designed for a laboratory environment and requires no sieving, only imaging of the aggregate. A luminous background material eliminates unwanted shadow effects. Particles are placed so they are not touching, thus the images of the aggregates are of good quality allowing an easy and accurate image analysis with no preprocessing. All three axial lengths of every particle are measured. The results can be plotted either as a continuous curve or showing the axial size of each and every particle. The latter allows the frequency of particles in the tails to be easily evaluated. Good agreement exists between the size distribution curves obtained from the Image Analysis and hand measurements using the Danish Box.

  • 5.
    Spross, Johan
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Soil and Rock Mechanics.
    Larsson, Stefan
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Soil and Rock Mechanics.
    On the observational method for groundwater control in the Northern Link tunnel project, Stockholm, Sweden2014In: Bulletin of Engineering Geology and the Environment, ISSN 1435-9529, E-ISSN 1435-9537, Vol. 73, no 2, p. 401-408Article in journal (Refereed)
    Abstract [en]

    For tunnelling in rock in Sweden, the public authorities usually set stringent requirements on low groundwater inflow to the tunnel, to minimise the risk of building settlement and the environmental impact. To improve this groundwater control, the potential application of the observational method in this matter was studied. A comparison was made between the actual implementation of groundwater control in the Northern Link road tunnel project in Stockholm and the definition of the observational method in Eurocode 7. The results showed that the groundwater control in the Northern Link project mainly agreed with the Eurocode. The significance of the deviations was discussed, and it was concluded that adopting the observational method for groundwater control so that it complied with Eurocode 7 would mostly entail simply a formalisation of today's procedures.

  • 6.
    Weixing, Wang
    et al.
    KTH. Chang’an University, China .
    Fengping, Wang
    Xiaojun, Huang
    Junfang, Song
    Rock fracture image acquisition using two kinds of lighting and fusion on a wavelet transform2016In: Bulletin of Engineering Geology and the Environment, ISSN 1435-9529, E-ISSN 1435-9537, Vol. 75, no 1, p. 311-324Article in journal (Refereed)
    Abstract [en]

    In order to obtain more precise information regarding rock fractures, images of a rock sample using two different light sources were acquired and fused. For image acquisition, an epoxy resin liquid was first injected into a fracture zone in situ, and when the epoxy resin was dry, the rock core sample, including the epoxy resin, was removed from the rock base. The rock core sample was then cut into multiple slices and images of the slices using ultraviolet (UV) and visible lighting were acquired. In order to fuse two slice images, an algorithm based on the redundant lifting, non-separable wavelet transform was studied and utilised. Fusion includes three primary steps for each pair of slice images: (1) applying the redundant lifting, non-separable wavelet transform to each image, and then approximating the two images separately; (2) fusing the approximated images corresponding to the decomposition level using certain rules and fusion operators for obtaining fusion coefficients; and (3) applying the fused wavelet coefficients to the redundant lifting non-separable wavelet transform. The results show that combining the proposed method of image acquisition and the image fusion algorithm is not only effective at obtaining a large volume of detailed rock fracture information, it is also an economical and easy to use method. By applying the new method, rock fractures can be easily detected, and many different parameters in different rock engineering applications can be measured and analyzed.

1 - 6 of 6
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