12.12.2016
14:53
von: Juergen

Geotechnical Engineering

FlowLineRedTracer  sandwave

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Fields of Work at the Federal Waterways Engineering and Research Institut (BAW), Bundesanstalt für Wasserbau auf Youtube

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Visualisation of flowlines in the soil below river bed using tracer fluid (experimental picture – left side) and sand waves initiated by travelling water waves causing pore water pressure variations delta u(z,t) inside the underlaying sand at river bed with upward (+) and downward (-) directed transient pore water flow (schematic picture – right side), see also the link to the paper for the IAHR-Conference 2007 in Venice (Iatly)

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TestPressureinSubsoil

More details and explanations to this video sequence (above) about the untertaken investigation may be found with the following Link to the paper (contribution 10) presented by Davis, Koenders & Köhler at the BAW-Workshop 2004 and at the end of this page down below.

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Saturationwaterpressuredistrbution

Distribution of saturation and pore water pressure in the tree phase system soil above and below piezometric level

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This internet page deals with submerged soil being recognized as a 3-phase-medium, containing gas, water and soil particles. Some of the research results of this phenomenon are presented, taking into account the direct influence on structure stability.

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Geotechnical Workshop about „Soil Liquefaction“ at the TU Freiberg (Saxony) from 14th to 15th of June 2012

Flyer, paper Köhler TU Freiberg 2012, powerpoint presentation Köhler TU Freiberg 2012

–>  Link zum Verlag Taylor & Francis

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Special research work undertaken by me at the Federal Waterways Engineering and Research Institute (BAW)  dealt with revetment and filter design at navigable inland water ways:

Filter and revetment design of water imposed embankments induced by wave and draw down loadings

Poster zur Standsicherheit von Deckwerken pd1Poster Standsicherheit von Deckwerken

Poster dealing with the phenomenon of excess pore water pressure at inland waterways caused by navigating vessels and their influence on revetment stability (left poster) as well as with experimental investigation methods using endoscopic and digital image processing  technique (right poster)

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Poster-Exhibition of the Federal Waterways Engineering and Research Institute (BAW) at the XIV. International Conference of Soil Mechanics and Geotechnical Engineering in Hamburg (XIVth ICSMGE) 1997

ICSMGEHamburg1997

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Absunk aus Schiffahrt

Water level draw down effect at an canal embankment caused by the passage of a navigating vessel

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Video-sequence of the water level draw down situation caused by the passage of a navigating vessel occurring at a flat sandy beach at the river Elbe near Hamburg (Youtube) –> small tsunami effect

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 Link to the list of publications by H.-J. Köhler

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Selected Publications:

Using digital image processing technique, which was established in a longstanding cooperation between the Federal Waterway Engineering and Research Institute (BAW) in Karlsruhe and Prof. B. Jähne and his research team at the  Research Institute for Scientific Image Processing Technique (IWR) at the Universität Heidelberg, a new measurement technique was succesfully introduced into the investigation methods to solve water soil interaction phenomena in soils under water. Many Diploma- and phD-Theses document this more than 10 years research activity between the Federal Waterway Engineering and Research Institute in Karlsruhe and Prof. B. Jähne and his research team at the University of Heidelberg. The results attained by this new digital image processing technique gained during our joint work are documented in a number of conference and journal papers.These investigational results of the experiments on particle motion at soil interfaces were printed as a short version in the following handbook:

See also the suggested text version submitted to be printed in this book.

A German publication presented at the Workshop 2004 at the University of Braunschweig describes one of the latest results gained from investigations on underwater embankments during wave attack undertaken in the test flume of the Waterway Engineering and Research Institute (BAW) in Karlsruhe:

The research led to clarifying results about the interaction of submerged soil particles and transient acting pore water flow. Meanwhile it has found its way into investigation strategies by different researchers dealing with similar research targets in order to solve questions in the fields of the engineering practice.

The following video sequence, gained by this newly developed digital image processing technique, shows the result of an investigation at a submerged soil body, which was loaded by water pressure fluctuations:

Auswertung zur Sedimetbewegung  Click on the lefthand image to start of the image video sequence (gif-file  –  5,95 kb)

ISTorino1999-Poster

  • Material Transport an Structure Changes at Soil-Water Interfaces, In: Proceedings of the 3rd International Conference Geofilters 2000, Warsaw, Poland, June 2000, Filters and Drainages in Geotechnical and Environmental Engineering, W. Wolski et al. (eds.), A.A. Balkema, Rotterdam, pp. 91 – 97, ISBN 9058091465, see also the poster for the Geofilters 2000-Conference „Material Transport…“ in Warschau:

WarschauGeofilters2000-Poster7MB

Bologna2000Poster

Istanbul2001-Poster

PosterPotsdam2002

  • Behaviour of near-saturated soils under cyclic wave loading,  in: Proceedings of the Third International Symposium on Deformation Characteristics of Geomaterials, IS Lyon 2003, Lyon, France, September 2003, Deformation Characteristics of Geomaterials, H. Di Benedetto et al. (eds), A.A.Balkema-Publishers, Lisse, pp 857 – 862, ISBN 905809 6041
  • Filters subjected to transient hydraulic loading, in: Proceedings of the 4th International Conference on Filters and Drainiage in Geotechnical and Environmental Engineering (Geofilters 2004), Windhuk, Südafrika, 2004, Filters and Drainages, et al. (eds.), 2004. A.A. Balkema, Rotterdam, pp 371 – 382

PosterSkemptonConferenceLondon2004

  • Unsaturated subsoil erosion protection in turbulent flow conditions
    by M. DAVIS, H.J. KÖHLER and M.A. KOENDERS                                                                       Link to Taylor  Francis (priview)
    IAHR – Journal of Hydraulic Research (JHR), 2006, Vol:44/Issue: 3
    Flow is considered over an obstacle placed on a coarse gravel layer that covers a sand layer. The pressure distribution as a function of position and time is obtained for partially saturated conditions in the subsoil. The flow in the open water and coarse layer is calculated using a lattice Boltzmann technique; the pressure in the subsoil is evaluated by means of an analytical solution using the lattice Boltzmann simulation as boundary condition. The results demonstrate where the greatest risk of damage to the subsoil may be located.
    Buy the full paper [in Adobe PDF format]

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Workshops 2002 and 2004 at the Federal Waterways and Research Institute Karlsruhe (BAW) – Bundesanstalt für Wasserbau Karlsruhe (BAW)

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BAW-Workshop 2002

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Program 2002

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Link to the Publications at the BAW-Workshop 2002
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  • Contribution 4

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BAW-Workshop 2004
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Turbulence at sea and river beds – foto originates from research experiments undertaken in an experimental flume at the Federal Waterway and Research Institute Karlsruhe (BAW) and presented at the BAW-Workshop 2004

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Program 2004

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Link to the Publications at the BAW-Workshop 2004

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Auswertung zur Sedimetbewegung Durchmischung farbig markierter Sandschichten (Fluidisierung) Digitale Bildauswertung

The preceding images above show experimental results of investigations undertaken on submerged soil in order to evaluate movements of a soil body caused by water level draw down loading. In order to distinguish between the movements of the whole soil body and its individual soil particles the following video sequence (moving soil segment) describes the process of heaving during a water level draw down loading. The image shows a vertical plane cut section of the size 6 x 6 mm. This image sequence is taken at the interface between an underlaying sand layer covered by a 10 cm thick protection layer of gravel, whilst interweaving pixel movements were simultaneously recorded by an endoscopic measuring technique during the loading phase. Using image processing technique the grabbed pixel movements were analyzed in order to distinguish between diverging and rotating motion. All single pixels of the image were evaluated by different especially developed algorithms to interpret the video sequences by a digital image analyzing technique gaining the interweaving motion of water and soil particles (sediment motion). The preceding video sequence shows the mass motion of the heaving soil body under observation together with the interpreted rotating and diverging motions in order to calculate the observed vector field.

Using digital image processing technique, which was established in a longstanding cooperation between the Federal Waterway Engineering and Research Institute (BAW)  in Karlsruhe and Prof. B. Jähne and his research team at the  Research Institute for Scientific Image Processing Technique (IWR) at the Universität Heidelberg, a new measurement technique was succesfully introduced into the investigation methods to solve water soil interaction phenomena in soils under water. Many Diploma- and phD-Theses document this more than 10 years research activity between the Federal Waterway Engineering and Research Institute (BAW) in Karlsruhe and Prof. B. Jähne and his research team at the University of Heidelberg. The results attained by this new digital image processing technique gained during our joint work are documented in a number of conference and journal papers. See also the following information in:

A German written publication presented at the Workshop 2004 at the University of Braunschweig describes one of the latest results gained from investigations on underwater embankments during wave attack undertaken in the test flume of the Federal Waterways Engineering and Research Institute (BAW) in Karlsruhe:

The research led to clarifying results about the interaction of submerged soil particles and transient acting pore water flow, which meanwhile has found its way into investigation strategies by different researchers dealing with similar research targets in order to solve questions in the fields of the engineering practice.

The following video sequence shows the result of an investigation at a submerged soil body, which was loaded by water pressure fluctuations, gained by this newly developed digital image processing technique:

Auswertung zur Sedimetbewegung  Click on the lefthand image to start the image video sequence (gif-file  –  5,95 kb)

The reason for this mass motion are tiny small gas bubbles occluded in the pore water of naturally submerged soils. These gas enclosures may cause transient water and soil flow motions, if external pressure changes (rising or reducing pressures) act on such soils. Pressure changes may therefore cause the increase or decrease in volume of the gas bubbles contained in the pore water according to Boyle-Mariot´s law, if rapid water level changes take place. In order to prevent or at least significantly hinder such processes of volume changes by the gas bubbles a satisfactory size of top load on the soil body is needed in order to minimize the endangering soil structure changes.

Porenwasserdruckmessung in der BöschungPorenwasserdruckabbau Modellvorstellung zur Volumenänderung einer Gasblase bei äußerer Druckänderung

Where pressure changes take place much faster than the value of the described pore water permeability k (m/s) of the soil under observation, measured in the terms of flow length in time (speed), the enclosed gas bubbles may be impaired from changing volume (dV/dt) within the simultaneously elapsing time. This causes transient pore water pressure potentials, time dependent to act in a delayed pore water pressure state. Either acting transient as an excess pore water pressure or as a not large enough adjusted smaller pore water pressure state. Such loading conditions lead to the initiation of  unsteady pore water flow, which may cause soil deformation within the time of  the pressure changes acting on the soil structures, if the soils are not highly enough protected by an appropriately selected heavy filter top load.

Where the filter protection layer is selected as an appropriately acting top load by means of a large amount of weight, the sediment motions may be prevented. Soil structure changes can therefore not take place. This may sufficient to ensure the soil against soil failure at unsteady state (hindered soil motion). Especially rapid water pressure changes, such as water level draw down or waves causing water pressure changes, i.e due to navigational traffic at water ways, may easily cause destabilisation of the soil at  river and sea beds or under water embankments. (see following image).

Absunk aus Schiffahrt

Hydraulic loading due to water level draw down and waves

Scheme of the hydraulic loading influence on bed and embankment stability in navigational canals

Hydraulic scheme of the water level draw down loading, caused by the passage of a vessel in the canal, endangering bed and embankment stability at navigational waterways

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Revetment Design Guide published in:

Bulletin No. 88  of the Federal Waterways Engineering and Research Institute (Bundesanstalt für Wasserbau), Karlsruhe • August• 2005, ISSN 0572-5801, Principles for the Design of Bank and Bottom Protection for Inland Waterways
by the members of  the Working Group “Revetments for Waterways“ of the Federal Waterways Engineering and Research Institute (BAW) Karlsruhe, 2005                       English Version of the GBB) published in the Mitteilungsblatt Nr. 88 of the Federal Waterways Engineering and Research Institute  (BAW)  Karlsruhe, 2005

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The following image shows an experimental setup of a coloure coded stone rip rap revetment structure under investigation tested in the wave flume at the Federal Waterways Engineering and Research Institute (BAW), Karlsruhe, against wave impact. At a model scale of 1:1 these wave attack experiments were undertaken in order to investigate the stability of stone rip rap revetment structures against water level lowering and surging or breaking waves. Valuable decisions for the design of revetments about the requested stone size and revetment structure thickness could be gained from the results of these experiments, which have been very useful in establishing new design rules for safe revetment structures (see also the link to the English version of the guide lines for revetment design (GBB 2004), published in 2004 and 2005 by the Federal Waterways Engineering and Research Institute (BAW) Karlsruhe.   

BAW-Versuche

Wave attack on an embankment in the test flume at the BAW Karlsruhe

OscillatingWaves

Scheme of the oscillating wave impact on the pore pressure response inside the subsoil

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The content of gas enclosures in the pore water gains therefore not only a direct significance for the construction of water ways, its influence stretches out to all fields of soil mechanics and foundation engineering. Especially for stability calculations and safety estimations of retaining wall structures, embankments and ground cut sections these gas enclosures in the pore water of natural submerged soils gain importance and need to be taken into account. Different application examples are documented in a number of publications and papers presented at different international conferences and in the Newsletters of the Federal Waterways Engineering and Research Institute (BAW).

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The following poster prepared for the “Skempton Memorial Conference”, held in London 2004, describes for instance three of such essential influencing structure cases, which are also printed in the Conference Proceedings and may be reached directly with the following link.          

Schwab, R., Köhler, H.-J. & Schulze, R. 2004 Pore water compressibility and soil behaviour – excavations, slopes and draining effects. In: Proceedings of the A.W. Skempton Memorial Conference 2004, London, UK, March 2004, R.J. Jardine et al. (eds), Thomas Telford Ltd, London, Vol. 2, pp. 1169 – 1182, ISBN 0727732641,
http://public.hj-koehler.de/PapSchwKoehSchuSkempton2004.pdf

PosterSkemptonConferenceLondon2004

Poster prepared for the Skempton Memorial Conference 2004 in London

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ChristmascardBAW2000

Christmas Card 2000 of the Federal Waterways Engineering Institute (BAW) pointing at our research work initiated by the „Filter and Erosion Research Club (FERC)“

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As soon as the research targets were published in 1997 an international research structure  –  Filter and Erosion Research Club (FERC)  –  was established between the  Federal Waterways Engineering and Research Institute (BAW) Karlsruhe (Germany), Rijkswaterstaat-Institute Delft (DWW) (The Netherlands), Institute for Scientific Image Processing Technique (IWR) at the University of Heidelberg (Germany), Kingston University (Great Britain – UK) and Institute for Hydromechanics (IfH) at the University (TH) Karlsruhe (Germany), which supported different research projects to investigate hydrodynamic imposed filter and erosion structures. See also the following publications, dealing with this subject:

  Link to Taylor  Francis (priview)

 IAHR – Journal of Hydraulic Research (JHR), 2006,Vol:44/Issue: 3 Flow is considered over an obstacle placed on a coarse gravel layer that covers a sand layer. The pressure distribution as a function of position and time is obtained for partially saturated conditions in the subsoil. The flow in the open water and coarse layer is calculated using a lattice Boltzmann technique; the pressure in the subsoil is evaluated by means of an analytical solution using the lattice Boltzmann simulation as boundary condition. The results demonstrate where the greatest risk of damage to the subsoil may be located.  Buy the full paper [in Adobe PDF format]

  • Contribution to the fluidisation of soils:
Direct visualisation of underwater phenomena in soil-fluid interaction and analysis of the effects of an ambient pressure drop on unsaturated media
by H.J. KÖHLER and M.A. KOENDERS                    
—> Link to Taylor & Francis (preview)
IAHR – Journal of Hydraulic Research (JHR), 2003,Vol:41/Issue: 1
A description is given of an apparatus in which a wide range of hydraulic conditions can be realised. A unique observation system using optical fibre based ‘endoscopes’ and an imaging system that includes a signficant digital processing element enables the visualisation of grain and fluid motion as well as air bubble behaviour in granular deposits of specified composition and geometry under externally imposed hydraulic conditions. Examples are given and a particular application in which a soil is studied that is fluidized by an external pressure drop. A description of the fluidized behaviour is given and the outcomes are cast in terms of a mathematical/physical model for fluidized material. This model is then used to predict the extent of a fluidized region in a one-dimensional situation
Buy the full paper [in Adobe PDF format]

Direct visualisation of underwater phenomena in soil-fluid interaction and analysis of the effects of an ambient pressure drop on unsaturated media

Some results of these latest investigations in 2004, using Lattice Boltzmann Simulations on erosion structures loaded by current and travelling waves, are shown in the following sketches. More details and explanations about the untertaken investigation may be found with the following Link to the paper (Beitrag 10) presented by Davis, Koenders & Köhler at the BAW-Workshop 2004.

Teststreamlines

Click on to the image (above) in order to start the image sequence of the calculated flow lines as a time dependent image sequence

Lattice Boltzmann Simulation for the current over an 10 cm high obstacle installed on a gravel bed protection layer of a thickness of 10 cm (uniform gravel with a median diameter of 10 mm) above a uniform base of fine sand and the occurrence of the initiated stream lines over the obstacle, above as well as inside the gravelly protection layer, running over the protected flume structure (water bed), superimposed by a simultaneously acting wave loading of sinosoidal travelling waves

TestPressureinSubsoil

Click on to the image (above) in order to start the calculated transient pore pressure response inside the sandy sublayer below the gravelly protection layer using the flow and water pressure regime originating from the Lattice Boltzmann Simulation.

Results were gained by using an analytical time dependent calculation scheme in order to evaluate the transient pore pressure response inside an underlaying base layer of fine sand. These took into account the results of the Lattice Boltzmann Simulation with current above a 10 cm high obstacle superimposed by synosoidal water waves travelling over an gravelly protection layer. The goal of this investigation is to evaluate the transient pore pressure response inside the underlaying base of the uniform fine sand layer below the 10 cm thick protection layer of uniform gravel, consisting of grain particles with a median diameter of 10 mm, caused by the hydrodynamic loading (current and waves) acting inside and above the water bed.

Link to the Sketch of this Lattice Boltzmann Simulation as pdf-file

Link to the results of a Lattice-Boltzmann-Simulation visualising the calculated streamlines of an horizontal turbulent water current above a gravilly water bed hindered by an obstacle.

The above mentioned research projects have been succesfully finished in 2004.

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