Change search
Refine search result
1 - 10 of 10
CiteExportLink to result list
Permanent link
Cite
Citation style
  • apa
  • harvard1
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf
Rows per page
  • 5
  • 10
  • 20
  • 50
  • 100
  • 250
Sort
  • Standard (Relevance)
  • Author A-Ö
  • Author Ö-A
  • Title A-Ö
  • Title Ö-A
  • Publication type A-Ö
  • Publication type Ö-A
  • Issued (Oldest first)
  • Issued (Newest first)
  • Created (Oldest first)
  • Created (Newest first)
  • Last updated (Oldest first)
  • Last updated (Newest first)
  • Disputation date (earliest first)
  • Disputation date (latest first)
  • Standard (Relevance)
  • Author A-Ö
  • Author Ö-A
  • Title A-Ö
  • Title Ö-A
  • Publication type A-Ö
  • Publication type Ö-A
  • Issued (Oldest first)
  • Issued (Newest first)
  • Created (Oldest first)
  • Created (Newest first)
  • Last updated (Oldest first)
  • Last updated (Newest first)
  • Disputation date (earliest first)
  • Disputation date (latest first)
Select
The maximal number of hits you can export is 250. When you want to export more records please use the Create feeds function.
  • 1.
    Rasul, Hedi
    et al.
    Koya University.
    Zou, Liangchao
    KTH, School of Architecture and the Built Environment (ABE), Sustainable development, Environmental science and Engineering, Resources, Energy and Infrastructure.
    Olofsson, Bo
    KTH, School of Architecture and the Built Environment (ABE), Sustainable development, Environmental science and Engineering, Water and Environmental Engineering.
    Monitoring of moisture and salinity content in an operational road structure by electrical resistivity tomography.In: Near Surface Geophysics, ISSN 1569-4445, E-ISSN 1873-0604Article in journal (Refereed)
    Abstract [en]

    Moisture dynamics in road systems significantly affect road structure design and maintenance. This study analysed moisture dynamics in a cross-section of motorway (the E18) in Sweden during a one-year period through in situ monitoring using electrical resistivity tomography (ERT). The monitoring methodology was assessed since resistivity can provide a good proxy for monitoring moisture in the road structure. Monthly electrical resistivity was calculated by inverting resistivity data along a pre-installed electrical resistivity line beneath the surface asphalt layer of the road at the test site. The electrical resistivity data were then statistically analysed and correlated with local climate data, i.e. precipitation and temperature, and with ground parameters such as moisture content. The results showed high variation in resistivity in the road surface layer and road shoulders depending on weather conditions, water flow and other surface activities. In general, negative correlations between electrical resistivity and precipitation were observed. The results also indicated possible retardation of de-icing salt after accumulating in the top layer during winter. These findings advance understanding of the moisture dynamics in roads and can help improve pavement design in response to future climate change.

  • 2.
    Shamu, John
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Soil and Rock Mechanics.
    Zou, Liangchao
    KTH, School of Architecture and the Built Environment (ABE), Sustainable development, Environmental science and Engineering, Resources, Energy and Infrastructure.
    Kotzé, Reinhardt
    Incipientus Ultrasound Flow Technologies AB, Sweden.
    Wiklund, Johan
    Incipientus Ultrasound Flow Technologies AB, Sweden.
    Håkansson, Ulf
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Soil and Rock Mechanics. Skanska Sweden AB, Sweden.
    Radial Flow Velocity Profiles of a Yield Stress Fluid between Smooth Parallel DisksManuscript (preprint) (Other academic)
  • 3.
    Zou, Liangchao
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Sustainable development, Environmental science and Engineering, Resources, Energy and Infrastructure.
    Håkansson, U.
    KTH.
    Cvetkovic, Vladimir
    KTH, School of Architecture and the Built Environment (ABE), Sustainable development, Environmental science and Engineering, Resources, Energy and Infrastructure.
    Impacts of elastic jacking on rock grouting2018In: ISRM International Symposium - 10th Asian Rock Mechanics Symposium, ARMS 2018, International Society for Rock Mechanics , 2018Conference paper (Refereed)
    Abstract [en]

    The injection pressure is an important design and operational parameter in rock grouting since it controls the grout penetration length and may cause harmful mechanical deformation of the rock mass, such as opening/dilation of the fractures, referred to as jacking. At present, modeling of rock grouting mainly relies on analytical models where the impact of jacking on the grout penetration in rock fractures is not considered. In this study, we present a hydro-mechanical coupled model for rock grouting in a single one-dimensional rock fracture, with consideration of jacking and two-phase flow, i.e. cement grout and groundwater. It assumes that the cement grouts are Bingham fluids and that the rock matrix is an elastic material. The fracture is simplified as a pair of smooth parallel plates. A finite element method (FEM) code is developed to iteratively solve the two-phase flow in the fracture and the elastic deformation of the rock matrix. Two cases with and without consideration of jacking are simulated and compared. The results generally show that jacking of fractures significantly affects the grout penetration in the fracture, which should be properly considered in modeling of rock grouting. This numerical model is able to describe more realistic physical processes in rock grouting, which can be used to estimate the optimal injection pressure in practice. 

  • 4.
    Zou, Liangchao
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Sustainable development, Environmental science and Engineering, Resources, Energy and Infrastructure.
    Håkansson, Ulf
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering.
    Cvetkovic, Vladimir
    KTH, School of Architecture and the Built Environment (ABE), Sustainable development, Environmental science and Engineering, Resources, Energy and Infrastructure.
    Cement grout propagation in two-dimensional fracture networks: Impact of structure and hydraulic variability2019In: International Journal of Rock Mechanics And Mining Sciences, ISSN 1365-1609, E-ISSN 1873-4545, Vol. 115, p. 1-10Article in journal (Refereed)
    Abstract [en]

    Analysis of cement grout propagation in water-saturated two-dimensional discrete fracture networks is presented in this study. A two-phase flow model for Bingham fluids flow in a single saturated fracture is extended to simulate cement grouts propagation in saturated networks. Using this extended model, the impacts of network structure and hydraulic variability, i.e., network geometry and aperture distribution, on the propagation process are investigated through numerical simulations. Cement grout propagation in 50 realizations of a two-dimensional discrete fracture network (2D DFN) are simulated with different cases of aperture variability, i.e. constant aperture, uncorrelated and length-correlated heterogeneous apertures following a truncated lognormal distribution. The results indicate that network structure and hydraulic variability significantly affect the grout propagation in 2D DFN systems. The randomized network structure and uncorrelated heterogeneous apertures significantly delay the propagation rate and largely increase the variability range of the propagation volume fraction. In contrast, in the case with length-correlated heterogeneous apertures, the propagation rate increases, while the variability range and rate of change of the propagation volume fraction decreases. The extended two-phase flow model for fracture networks and the simulation results presented in this work are useful for basic understanding of the processes relevant for design, monitoring and execution of rock grouting.

  • 5.
    Zou, Liangchao
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Sustainable development, Environmental science and Engineering, Resources, Energy and Infrastructure.
    Håkansson, Ulf
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Soil and Rock Mechanics.
    Cvetkovic, Vladimir
    KTH, School of Architecture and the Built Environment (ABE), Sustainable development, Environmental science and Engineering, Resources, Energy and Infrastructure.
    Modeling of rock grouting in saturated variable aperture fractures2018In: Proceedings of Bergdagarna 2018., 2018, p. 79-87, article id 10Conference paper (Refereed)
    Abstract [en]

    Modeling and analysis of cement grouts flow in rock fractures is important in the design, execution and monitoring of grouting in fractured rocks. At present, modeling of rock grouting mainly relies on analytical models, e.g., the real time grouting control (RTGC) method. In the RTGC method, it is assumed that the rock fractures are consisting of smooth parallel plates or disks and water flow is neglected. However, in reality, the natural rock fractures are commonly consisting of complex rough-walled surfaces and are filled with groundwater; therefore, grouting is actually a multiphase (non-Newtonian grouts and groundwater) flow process in rough-walled rock fractures with variable apertures. In this study, we present an efficient one-dimensional (1D) numerical model for modeling of rock grouting in a single rock fracture with consideration of multiphase flow and variable apertures. It is assumed that the cement grouts are Bingham fluids and that the analytical solution for flowrate with a given pressure gradient in a pair of smooth parallel plates is locally applicable. A time-dependent advection equation is used to describe the interface (between the grout and groundwater) propagation. A finite element method (FEM) code is developed to iteratively solve the mass balance and the interface advection equations. The numerical simulations are compared with the RTGC method. It generally shows that water flow significantly affect grouts penetration in the fracture, especially for the grouts with relatively lower viscosity. The variable aperture significantly postpones the penetration process compared with that of constant aperture. This numerical model is able to describe more realistic physical processes and geometry conditions in rock grouting, which can be readily used in practice to reduce the potential uncertainties in application of simplified analytical models.

  • 6.
    Zou, Liangchao
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Sustainable development, Environmental science and Engineering, Resources, Energy and Infrastructure.
    Håkansson, Ulf
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Soil and Rock Mechanics. Skanska AB .
    Cvetkovic, Vladimir
    KTH, School of Architecture and the Built Environment (ABE), Sustainable development, Environmental science and Engineering, Resources, Energy and Infrastructure.
    Non-Newtonian grout flow in single rough-walled rock fractures2019Conference paper (Refereed)
    Abstract [en]

    Modeling of cement grout flow in rock fractures plays an important role in the design of rock grouting. Cement grouts used in rock grouting practice are typical non-Newtonian fluids containing yield stress, and are often assumed as Bingham fluids. Natural rock fractures typically consist of rough surfaces. Therefore, in reality, rock grouting process actually involves non-Newtonian fluid flow in rough-walled fractures, which is rarely studied in the literature. In this work, we focus on the impact of surface roughness and present direct numerical simulations of non-Newtonian grouts flow in single rough-walled fractures, using a regularized method to approximate the yield-stress. The rough-walled rock fracture models are created from a laser-scanned surface of a granite rock sample, to represent realistic features of natural rock fractures. The numerical results generally show nonlinear behaviors of non-Newtonian fluid flow in rough-walled fractures. The surface roughness significantly reduces the effective transmissivity when Reynolds number is relatively large. The obtained result can be used for upscaling analysis in practice, in order to reduce the potential uncertainties caused by the surface roughness of the rock fractures.

    The full text will be freely available from 2020-01-01 23:22
  • 7.
    Zou, Liangchao
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Sustainable development, Environmental science and Engineering, Resources, Energy and Infrastructure.
    Håkansson, Ulf
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Soil and Rock Mechanics.
    Cvetkovic, Vladimir
    KTH, School of Architecture and the Built Environment (ABE), Sustainable development, Environmental science and Engineering, Resources, Energy and Infrastructure.
    Two-phase cement grout propagation in homogeneous water-saturated rock fractures2018In: International Journal of Rock Mechanics And Mining Sciences, ISSN 1365-1609, E-ISSN 1873-4545, Vol. 106, p. 243-249Article in journal (Refereed)
    Abstract [en]

    Modeling of cement grout flow in rock fractures is important for the design, monitoring and execution of rock grouting that is widely used in a variety of rock engineering applications. This study presents a mathematical model based on the Reynolds flow equation for cement grout flow in a homogeneous water-saturated rock fracture. The model is based on two-phase flow, i.e. grout as a Bingham fluid and groundwater as a Newtonian fluid, and is used for investigating the importance of the water phase in rock grouting. The modeling results for the two-phase flow generally show the importance of the water phase that can significantly affect the pressure distribution and grout penetration in the fracture, especially under the condition of grout hardening. Such effects depend on the viscosity ratio between the grout and groundwater, which becomes increasingly important for cases with smaller values of the viscosity ratio. The grout density also affects the grout penetration length. Applying an analytical solution based on single-phase flow, i.e. neglecting the impact of groundwater flow, for modeling grout injection, will generally overestimate the penetration length.

  • 8.
    Zou, Liangchao
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Sustainable development, Environmental science and Engineering, Resources, Energy and Infrastructure.
    Jing, Lanru
    KTH, School of Architecture and the Built Environment (ABE), Sustainable development, Environmental science and Engineering, Land and Water Resources Engineering.
    Cvetkovic, Vladimir
    KTH, School of Architecture and the Built Environment (ABE), Sustainable development, Environmental science and Engineering, Resources, Energy and Infrastructure.
    Effect of sorption on solute transport in a single rough rock fracture2017In: 13th ISRM International Congress of Rock Mechanics, International Society for Rock Mechanics , 2017Conference paper (Refereed)
    Abstract [en]

    Sorption process plays a significant role for solute retardation in rock fractures. In this paper, for the aim to investigate the effect of sorption on solute transport in a single rough fracture, a 2D model of representative single rock fracture was built and its roughness was statistically characterized based on the measured data of rock surface topography by laser scanning. A Finite Volume Method (FVM) code was developed to solve the Navier-Stokes (NS) equations and transport equation for numerical modelling the process of fluid flow and solute transport in the rock fracture model. Two groups of simulations were conducted: with and without the consideration of the sorption process with different average flow velocities. The results show that the surface roughness increased the complexities of flow fields, and the non-linear sorption process plays a significant role in the retardation of solute transport through rock fractures. The sorption process caused an obvious lagging time in both the solute concentration fields (plumes) and corresponding breakthrough curves. This lagging time increases with the distance from the inlet boundary, and relatively decreases with the increase of mean velocities.

  • 9.
    Zou, Liangchao
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Sustainable development, Environmental science and Engineering, Land and Water Resources Engineering.
    Jing, Lanru
    KTH, School of Architecture and the Built Environment (ABE), Sustainable development, Environmental science and Engineering, Land and Water Resources Engineering.
    Cvetkovic, Vladimir
    KTH, School of Architecture and the Built Environment (ABE), Sustainable development, Environmental science and Engineering, Land and Water Resources Engineering.
    Modeling of Solute Transport in a 3D Rough-Walled Fracture-Matrix System2017In: Transport in Porous Media, ISSN 0169-3913, E-ISSN 1573-1634, Vol. 116, no 3, p. 1005-1029Article in journal (Refereed)
    Abstract [en]

    Fluid flow and solute transport in a 3D rough-walled fracture-matrix system were simulated by directly solving the Navier-Stokes equations for fracture flow and solving the transport equation for the whole domain of fracture and matrix with considering matrix diffusion. The rough-walled fracture-matrix model was built from laser-scanned surface tomography of a real rock sample, by considering realistic features of surfaces roughness and asperity contacts. The numerical modeling results were compared with both analytical solutions based on simplified fracture surface geometry and numerical results by particle tracking based on the Reynolds equation. The aim is to investigate impacts of surface roughness on solute transport in natural fracture-matrix systems and to quantify the uncertainties in application of simplified models. The results show that fracture surface roughness significantly increases heterogeneity of velocity field in the rough-walled fractures, which consequently cause complex transport behavior, especially the dispersive distributions of solute concentration in the fracture and complex concentration profiles in the matrix. Such complex transport behaviors caused by surface roughness are important sources of uncertainty that needs to be considered for modeling of solute transport processes in fractured rocks. The presented direct numerical simulations of fluid flow and solute transport serve as efficient numerical experiments that provide reliable results for the analysis of effective transmissivity as well as effective dispersion coefficient in rough-walled fracture-matrix systems. Such analysis is helpful in model verifications, uncertainty quantifications and design of laboratorial experiments.

  • 10.
    Zou, Liangchao
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Sustainable development, Environmental science and Engineering, Land and Water Resources Engineering.
    Jing, Lanru
    KTH, School of Architecture and the Built Environment (ABE), Sustainable development, Environmental science and Engineering, Land and Water Resources Engineering.
    Cvetkovic, Vladimir
    KTH, School of Architecture and the Built Environment (ABE), Sustainable development, Environmental science and Engineering, Resources, Energy and Infrastructure.
    Shear-enhanced nonlinear flow in rough-walled rock fractures2017In: International Journal of Rock Mechanics And Mining Sciences, ISSN 1365-1609, E-ISSN 1873-4545, Vol. 97, p. 33-45Article in journal (Refereed)
    Abstract [en]

    Nonlinear flow in 3D rough-walled rock fractures is simulated by solving the Navier-Stokes equations. The emphasis is on the impact of shear-caused aperture changes (variable apertures and asperity contacts) and flow conditions (inertial term) upon nonlinear flow behavior. In order to compare shear effects, two 3D fracture models, with and without shear, were established with identical initial rough-walled surfaces topographies of a realistic rock sample. Five groups of simulations with different inflow boundary conditions of flowrates/Reynolds numbers (Re) were conducted to demonstrate shear-enhanced nonlinearity of flow fields and limitations of local cubic law (LCL) approach. The flow results clearly show channeling flow along the preferential paths, transverse flow around the contact spots, and eddy flows behind contact spots with increasing Re, which cannot be observed in 2D models. The effective transmissivity of the 3D fracture model was calculated from the modeling results of velocity and pressure fields. The results showed that the effective transmissivity is a function of local apertures with important uncertainties even when Re is small (i.e. Re = 0.4 in this study), thus the validity of the transmissivity evaluation using LCL approach for nonlinear flow in 3D rough-walled rock fractures is questionable.

1 - 10 of 10
CiteExportLink to result list
Permanent link
Cite
Citation style
  • apa
  • harvard1
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf