Interaktion Strasse-Hangstabilität: Umsetzung

• Forschungsstelle: ASTRA SBT
• Projektnummer: VSS2010/502
• Projekttitel Englisch: Road-landslide interaction: Applications

Schlüsselwörter (Deutsch)

Hangrutschung, Strasse, Stabilitätsanalyse, Überwachung, Stabilisation

Schlüsselwörter (Englisch)

Landslide, road, stability analysis, monitoring, stabilization

Kurzbeschreibung (Deutsch)

Die zuverlässigste Art der Voraussage von Verschiebungen und Langzeitstabilität grosser Kriechhänge beruht auf der Rückrechnung von Bodenparametern, die mit Hilfe von geodätischen Messungen, so wie Erd- und Wasserdruck Messungen in der kriechenden Schicht bestimmt werden. Zusätzlich zu den konventionellen geodätischen Messungen wird vorgeschlagen, die Verschiebungen in einer den Kriechhang durchschneidenden Strasse mit Hilfe von Dehnungen in einem Glasfaserkabel zu messen. Dies kann auf zwei Arten dienlich sein: Einerseits kann die Gebrauchstauglichkeit der Strasse überwacht und andererseits können die Verschiebungen zur Berechnung der Hangstabilität und der Hangverschiebungen genutzt werden. Ein neuartiges Gerät, Inclino-Deformometer (IDM), soll eine zuverlässige Erddruckmessung der sich bewegenden Schicht erlauben. Dessen Messungen sollen ebenfalls in die Rückrechnung mit einfliessen. Mit einem neuen Verfahren zur chemischen Behandlung von Tonen kann die Durchlässigkeit erhöht werden, was zu einer „flexiblen“ Drainage des Hanges führt. Des Weiteren soll eine neuartige Behandlung von Böden mit Bakterien auf der einen Seite die allfälligen chemischen Rückstände, die bei der chemischen Behandlung übrig geblieben sind, abbauen und auf der anderen Seite durch eine Art Zementierung die Scherfestigkeit der rutschenden Schicht erhöhen. Die aus dieser Forschung gewonnenen Resultate dienen zur Voraussage des Verhaltens von Strassen und Rutschungen und sollen anschliessend für die Planung von Stabilisierungsmassnahmen herangezogen werden.

Kurzbeschreibung (Englisch)

The most reliable approach to the long-term displacement and stability analysis of the large creeping landslides is based on the back-calculation (inverse analysis) of soil parameters from observed displacements and measured earth and water pressures in the sliding layer. In addition to the conventional geodetic measurements, it is suggested to monitor the deformations of a road intersecting a landslide using a novel fiberoptics strain measurement technology. This could serve a double purpose: to monitor the health of the road structure and to provide a unique data for the inverse analysis of the landslide stability and displacements. A novel Inclino-Deformometer (IDM) will allow for the first time to measure reliably the earth pressures in the sliding layer contributing more unique data for the inverse analysis. Novel approach to chemical treatment of clayey soils will help to increase the soil permeability allowing for improved drainage in the sliding layer. Novel approach to biological treatment of soil will help to remediate effects of the chemicals on the environment and to increase the shear strength of soil due to the biomineralization. Results of the research will be used for prediction of the road and landslide behavior and for planning of the stabilization measures.

Projektbeschreibung (Englisch)

Task 1: Further development of the IDM

The Incline-Deformometer (IDM) is a novel device developed by IGT for back-calculation of the changes of earth pressure with support from the ASTRA/VSS grant VSS 2005/502 “Road-Landslide Interaction” (Schwager et al., 2009). In the first step, IDM measures the change in dimensions of an inclinometer pipe in the sliding layer. The change in shape is assumed to be caused by the changes in the surrounding stress field. In the second step, the measured deformations are used to back-calculate the change in pressure via inverse analysis of the corresponding boundary value problem of a plastic pile surrounded by grout and soil under a changing stress state.

Task 2: Further development of the FO landslide monitoring techniques

Distributed fibre optic strain sensing technology (BOTDA Brillouin optical time domain analysis) opens new horizons in the field of landslide detection and infrastructure monitoring compared to traditional technologies. The technology uses special tight buffered single mode fibre optic cable for strain and temperature measurement along the fiber. It offers a high resolution of a few microstrains at a spatial resolution of 1m and large application lengths up to 30km.

Task 3: Development of chemical and biological stabilization techniques

Drainage of pore water pressures is an effective means to reduce the driving forces of creeping landslides. As conventional drainage systems have a high risk of failure due to differential displacement, a locally increased permeability in the soil itself provides an appropriately deformable drainage system. Infiltration of chemicals, that change the permeability of clayey soils, produces pipe-like zones around boreholes serving as flexible drainage pipes.

Using microorganisms and their specific metabolism is another possibility to improve soil properties in-situ. Soil bacteria can be placed and fed in critical zones by infiltration. Causing the formation of new minerals, these bacteria increase the cohesion between soil particles and thereby contribute to the improvement of slope stability.

Based on laboratory tests the efficiency of the above proposed methods to change soil parameters will be evaluated.

Task 4: Study of a naturally constrained landslide (Brattas, St. Moritz)

The Brattas landslide stops abruptly in the middle of the town of St. Moritz-Dorf. A special construction law for the effected area exists. The structures in this area have to be strong enough to resist the additional earth pressure and “swim” in the creeping landslide. But what about its long-term stability? If the earth pressure in the compression zone at the bottom of the landslide increases, it may eventually reach the passive pressure and lead to a catastrophic failure of the landslide. The task is to investigate the probability of this scenario. To this end the following subtasks will be performed.

Task 5: Study of an artificial constrained landslide (Combe Chopin)

For construction of the foundation of a bridge, a small landslide was stabilized by a retaining wall. During the construction, the anchors in the retaining wall were prestressed excessively, so that the landslide in its bottom part started moving uphill. At the moment the direction of the displacement has changed and it is now moving downhill. But will the retaining wall be overflown by the landslide in the future? The task is to investigate the probability of this scenario. To this end the following subtasks will be performed.

Task 6: Study of an unconstrained landslide (Braunwald)

The village of Braunwald is built on a creeping landslide. Special for this creeping landslide is the free pressure boundary condition at the bottom part of the landslide because the village is located on a natural terrace. An extensive drainage system has been planned but not yet installed. For assessment of the effectiveness and optimization of the drainage system the pore water pressure development in the landslide and shear strength degradation are of the greatest interest. How does this pore pressure effect the displacements? The task is to investigate these phenomena. To this end the following subtasks will be performed.

Task 7: Study of the boundry conditions at the bottom of the landslide (Ganter):

The Ganter Bridge is built on an active creeping landslide. Some of its piers are founded in a creeping area within large caissons. The upper part of such pier can be shifted uphill to correct the displacements. At the bottom part of the creeping landslide there is a riverbed which provides a boundary. Is this a stiff or an elastic boundary? Will the pressure at the bottom grow and exceed the passive pressure causing a collapse? The task is to investigate the probability of this scenario. To this end the following subtasks will be performed.

Task 8: Study of the effect of reactivation of a landslide by construction (Via Laret, St. Moritz)

Via Laret landslide in St Moritz has been discovered in 2008. The hypothesis is that this is a dormant landslide being sporadically reactivated by the construction in the area. When reactivated it causes devastating damage to the property. The task is to collect information to verify this hypothesis. To this end the following subtasks will be performed.

Task 9: A novel method for determining soil stiffness in a creeping body (Leimbach)

Leimbach landslide is a slowly creeping landslide in Zurich. It has been used as a testing ground for the IDM application. The task is to demonstrate that combining IDM measurements with inclinometer and geodetic measurements allows for determination of not only the pressure changes but also of the stiffness of the sliding layer.

Task 10: General conclusions and recommendations

Based on the results of the proposed research the conclusions and recommendations will be made.

Erwartete Erkenntnisse/ Nutzen, Nutzniesser (Englisch)

The research will improve our understanding of different mechanisms of creeping landslides with different boundary conditions. The novel analysis and monitoring tools developed in this research will enhance our ability to deal with a complex phenomenon of the creeping landslides in terms of prediction of their long term stability and displacements. When applied in the framework of this project to the real landslides in Switzerland, these tools will help to make decisions with respect to the landslide stabilization and hazard mitigation in an attempt to reduce the damage to the infrastructure and economy.

Methoden (Englisch)

PROPOSED RESEARCH

The task 1 “Further development of the IDM” will be divided into the following subtasks:

Subtask 1.1: Improvement of accuracy

To be able to back-calculate changes in earth pressures over a period of several years the first step of measuring deformations has to be improved. To avoid a possible shift the accuracy of the calibration of the device has to be enhanced.

The measurement of deformations can be improved as well by having more readings along the borehole, which allows an advanced interpretation and processing of the measured data.

Subtask 1.2: New analytical and numerical approaches to back-calculation of pressures

For the second step of the back-calculation of the pressures the relation between the measured deformations and the trial pressures will be developed. Because of physical and geometric non-linearities a numerical modeling approach is essential. Nevertheless, an attempt to develop a simplified analytical solution will be also made because of its simplicity in applications. Modeling approaches will be calibrated against full scale laboratory tests in the IDM box. In case of numerical models for inverse analysis the sensitivity has to be checked.

For the back-calculation it has to be taken into account that there are although deformations of the cross-section due to bending along the pipe. Additional correction has to be performed if the directions of principle stress do not coincide with the direction of the channels, in which the deformation is measured.

Subtask 1.3: Time dependency of measurements

For the back-calculation it is important to model the constitutive behaviour of the involved materials (i.e. pipe, grout and soil) in an appropriate way.

In case of the plastic material of the pipe the time dependency is the most important effect. The full scale laboratory creep tests will be carried out to study the viscous behaviour of the pipe. Element creep tests on the pipe material will be done as well.

Subtask 1.4: Effects of grout

The stiffness of the surrounding material of the inclinometer pipe has an important influence on the back-calculation. The full scale laboratory tests and element tests on common grout compounds will performed to quantify these effects. There will be suggestions made for an optimal stiffness of the grout in relation to the stiffness of the soil in respect to pressure measurements using IDM.

The task 2 “Further development of the FO landslide monitoring techniques” will be divided into the following subtasks:

Subtask 2.1: Design of cables and micro anchors

In landslide monitoring, a structure is rarely available for attaching the fiber optic cable (except roads, Iten et al., 2009) and therefore direct cable integration in soil is desirable. Extending fibre optic sensor measurements of strains and displacements directly into soil environment is not trivial for several reasons: vulnerable fibre optic cables tend to break during integration in the harsh soil environment and, additionally, soil can flow around the cable and thus, measured strain in the cable can be different to strain present in the soil. In order to prevent these undesired effects, robust cables and a micro-anchor concept were developed in the framework of a CTI project: CTI 9267.1 PFIW-IW “Novel fiber optic sensing systems for soil displacement monitoring”. Attached at discrete points along the cable, these micro-anchors connect the sensor cable to the moving soil until the bearing capacity of a single micro-anchor is reached.

In order to minimize the measurement error and to obtain a reliable novel sensor, a perfect adjustment of the micro-anchor size on fibre optic cable type, the sand covering depth and density is crucial. Therefore the behaviour in longitudinal direction of different types of cables and sizes of micro-anchors will be investigated in the framework of the CTI project in the Pullout Box in the IGT laboratory.

Subtask 2.2: Full scale shear zone simulation

In a typical landslide boundary with a shear zone, the fibre optic sensor is exposed to displacements in longitudinal and transversal direction. In order to asses the performance of this novel fiber optic sensor for soil displacements and to give a proof of the micro-anchor concept, a full scale simulation of a shear zone is intended in the framework of the CTI project. Different optimized cable types and anchor systems will be integrated at different depths in two rigid boxes with a shear zone in between. While one box is moved in steps, fiber optic strain measurements are taken and compared with the known applied strain in order to assess the measurement precision of this novel sensor under real conditions. Furthermore, the long term sensor behaviour (relaxation, temperature) can be investigated in this simulation.

Subtask 2.3: Further monitoring of the instrumented landslides approaches to back-calculation

In July 2008, a first field integration of this novel sensor was conducted. An 80m long sensor was integrated under a hiking path directly in soil, within a potential landslide. During the summer 2009 first strain measurements were successfully taken and further strain measurements in the near future are scheduled in order to provide data for characterization on this potential landslide.

Subtask 2.4: Improvement of interpretation techniques

A fibre optic strain measurement provides a continuous strain distribution with temperature compensation along the cable. In order to use this technology as a sensor not only for qualitatively detection and monitoring of landslide boundaries but also for quantitative measurements further studies and comparison with traditional technologies are necessary.

The task 3 “Development of chemical and biological stabilization techniques” will be divided into the following subtasks:

Subtask 3.1: Chemically enhanced drainage

Soil samples containing clay minerals will be treated with chemicals in order to assess the practicable increase of permeability. For that purpose, permeameter tests will be conducted to measure the change in hydraulic conductivity during infiltration of the dissolved chemicals. The adsorption behaviour of the chemicals will be investigated by determining a sorption isotherm in order to predict the required and the residual concentration of the chemicals in flow-through treatments.

Subtask 3.2: Bioremediation of the negative effects of the chemicals

In order to minimize the environmental effects of the chemicals, biological methods for degrading the residual chemicals after soil treatments will be investigated. Namely the cultivation of biodegrading microorganisms for the used chemicals will be carried out, especially considering their ability to live in soils.

Subtask 3.3: Strength increase via biomineralization

Soil bacteria will be used to increase the shear resistances of soils by means of cementation of soil particles. The change of shear strength due to microbially induced precipitation of calcite between soil particles will be examined by performing flow-through experiments with nutrient solutions and subsequent shearing of soil samples.

The task 4 “Study of a naturally constrained landslide (Brattas, St. Moritz)” will be divided into the following subtasks:

Subtask 4.1: field measurements

The following field measurements are proposed. The most important parameter - the change in the earth pressure in time at the bottom part – will be measured using the new Inclino-Deformometer. Additional GPS-measurements on geodetic points will show the displacements along the entire landslide, while inclinometer and piezometer measurements will show the change of displacements with depth and of the water pressures in time. Fiberoptic measurements will allow defining the horizontal and vertical landslide boundaries with a greater accuracy. Dilatometer measurements allow for measuring the stiffness of the sliding layer.

Subtask 4.2: laboratory tests

Ring shear tests will be performed on soil samples from the site to determine the shear strength dependency on the relative displacement. Oedometer tests allow for validation in the lab of the dilatometer stiffness measurements in the field.

Subtask 4.3: back-calculation using analytical model

A simplified analytical model will be developed, which will use the results of the field and laboratory measurements to back-calculate the missing soil parameters and predict the landslide behaviour in terms of the long-term stability and displacements.

Subtask 4.4: numerical verification of the analytical model

A more sophisticated finite element analysis will be performed to verify the simplifying assumptions of the analytical model.

Subtask 4.5: conclusions and recommendations

The conclusions with respect to the long term behaviour of the landslide and recommendations for its potential stabilization will be made.

The task 5 “Study of an artificial constrained landslide (Combe Chopin)” will be divided into the following subtasks:

Subtask 5.1: field measurements

The following field measurements are proposed. The most important parameter - the change in the earth pressure in time at the bottom part – will be back-calculated using the TRIVEC and anchor load cell measurements. Additional geodetical measurements will show the displacements along the entire landslide, while inclinometer and piezometer measurements will show the change of displacements with depth and of the water pressures in time.

Subtask 5.2: laboratory tests

Results of the previous investigatios will be used to determine the soil stiffness and the shear strength dependency on the relative displacement.

Subtask 5.3: back-calculation using analytical model

A simplified analytical model will be developed, which will use the results of the field and laboratory measurements to back-calculate the missing soil parameters and predict the landslide behaviour in terms of the long-term stability and displacements.

Subtask 5.4: numerical verification of the analytical model

A more sophisticated finite element analysis will be performed to verify the simplifying assumptions of the analytical model.

Subtask 5.5: conclusions and recommendations

The conclusions with respect to the long term behaviour of the landslide and recommendations for its potential stabilization will be made.

The task 6 “Study of an unconstrained landslide (Braunwald)” will be divided into the following subtasks:

Subtask 6.1: field measurements

The following field measurements are proposed. The change in the earth pressure in time will be measured in different cross-sections using the new Inclino-Deformometer to confirm existence of compression and extension zones and to back-calculate the soil stiffness and shear strength. Additional GPS-measurements on geodetic points will show the displacements along the entire landslide, while inclinometer and piezometer measurements will show the change of displacements with depth and of the water pressures in time.

Subtask 6.2: laboratory tests

Ring shear tests will be performed on soil samples from the site to determine the shear strength dependency on the relative displacement. Oedometer tests allow for validation in the lab of the stiffness backcalculated from IDM measurements in the field.

Subtask 6.3: back-calculation using analytical model

A simplified analytical model will be developed, which will use the results of the field and laboratory measurements to back-calculate the missing soil parameters and predict the landslide behaviour in terms of the long-term stability and displacements.

Subtask 6.4: numerical verification of the analytical model

A more sophisticated finite element analysis will be performed to verify the simplifying assumptions of the analytical model.

Subtask 6.5: conclusions and recommendations

The conclusions with respect to the long term behaviour of the landslide and recommendations for its potential stabilization will be made

The task 7 “Study of the boundary conditions at the bottom of the landslide (Ganter)” will be divided into the following subtasks:

Subtask 7.1: field measurements

The following field measurements are proposed. The most important parameter - the change in the earth pressure in time at the bottom part – will be measured using the new Inclino-Deformometer. Additional GPS-measurements on geodetic points will show the displacements along the entire landslide, while inclinometer and piezometer measurements will show the change of displacements with depth and of the water pressures in time. Dilatometer measurements allow for measuring the stiffness of the sliding layer.

Subtask 7.2: laboratory tests

Ring shear tests will be performed on soil samples from the site to determine the shear strength dependency on the relative displacement. Oedometer tests allow for validation in the lab of the dilatometer stiffness measurements in the field.

Subtask 7.3: back-calculation using analytical model

A simplified analytical model will be developed, which will use the results of the field and laboratory measurements to back-calculate the missing soil parameters and predict the landslide behaviour in terms of the long-term stability and displacements.

Subtask 7.4: numerical verification of the analytical model

A more sophisticated finite element analysis will be performed to verify the simplifying assumptions of the analytical model.

Subtask 7.5: conclusions and recommendations

The conclusions with respect to the long term behaviour of the landslide and recommendations for its potential stabilization will be made.

The task 8 “Study of the effect of reactivation of a landslide by construction (Via Laret, St. Moritz)” will be divided into the following subtasks:

Subtask 8.1: field measurements

The following field measurements are proposed. The change in the earth pressure will be measured using the new Inclino-Deformometer. Additional GPS-measurements on geodetic points will show the displacements along the entire landslide, while inclinometer and piezometer measurements will show the change of displacements with depth and of the water pressures in time. Fiberoptic measurements will allow defining the horizontal landslide boundaries with a greater accuracy. Dilatometer measurements allow for measuring the stiffness of the sliding layer.

Subtask 8.2: laboratory tests

Ring shear tests will be performed on soil samples from the site to determine the shear strength dependency on the relative displacement. Oedometer tests allow for validation in the lab of the dilatometer stiffness measurements in the field.

Subtask 8.3: numerical model

A simplified finite element model will be developed, to study effects of excavation on the landslide reactivation.

Subtask 8.4: conclusions and recommendations

The conclusions with respect to the long term behaviour of the landslide and recommendations for its potential stabilization will be made.

The task 9 “A novel method for determining soil stiffness in a creeping body (Leimbach)” will be divided into the following subtasks:

Subtask 9.1: field measurements

The following field measurements are proposed. An inclinometer pipe has been installed to the depth of 74 m. The changes in the inclinometer pipe diameters will be measured using the new IDM. Geodetical measurements will show the displacements around the inclinometer pipe, while inclinometer and piezometer measurements will show the change of displacements with depth and of the water pressures in time. Dilatometer measurements allow for measuring the stiffness of the sliding layer.

Subtask 9.2: laboratory tests

Oedometer tests allow for validation in the lab of the dilatometer stiffness measurements in the field.

Subtask 9.3: backcalculation of the soil stiffness from IDM measurements

An inverse boundary problem is solved numerically using as an input the changes in the inclinometer pipe diameters measured using IDM and displacements around the inclinometer pipe from geodetical measurements. The solution will produce the stiffness of soil and the change in the earth pressure.

Subtask 9.4: validation

The soil stiffness back-calculated from the previous subtask is going to be validated against the stiffness parameters obtained from field (dilatometer) and lab (oedometer) tests.

Task 10: General conclusions and recommendations

Based on the results of the proposed research the conclusions and recommendations will be made with respect to:

- the long term behaviour of the studied landslides;

- their potential stabilization;

- proper procedures for landslide monitoring and analysis;

- applicability of novel sensor technologies for landslide monitoring;

- applicability of the novel chemical and biological stabilization techniques;

- road infrastructure monitoring and maintenance.

Task 10 Final Report and Project Evaluation

In the last step the results from all previous tasks with conclusions and recommendations will be summarized in the final report. Additional an extended summary in German will be added to the final report. Recommendations with respect to further research programs in the obeserved field will be formulated.

PERSONNEL (Graphik 5)

As individuals, the project Primary Investigators (Pis) are presently active in the theoretical, laboratory and field research related to construction, geomechanics, and geotechnical engineering. The table below provides a brief summary on the Pis areas of expertise and their contribution to the proposed research.

Graphik 5

BUDGET (Graphik 6)

The wide scope of the project will require significant human resources. The required monitoring equipment, computers and software will be provided by Prof. Puzrin's research funds.

Graphik 6

Zugehörige Dokumente

• VSS 2010 502 Graphik 5 und 6.pdf [PDF] 289 kB

Spezielle Geräte und Installationen (Englisch)

The Inclino-Deformometer (IDM) is a novel device developed by IGT for back-calculation of the changes of earth pressure with support from the ASTRA/VSS grant VSS 2005/502 “Road-Landslide Interaction” (Schwager et al., 2009). In the first step, IDM measures the change in dimensions of an inclinometer pipe in the sliding layer. The change in shape is assumed to be caused by the changes in the surrounding stress field. In the second step, the measured deformations are used to back-calculate the change in pressure via inverse analysis of the corresponding boundary value problem of a plastic pile surrounded by grout and soil under a changing stress state.

Distributed fibre optic strain sensing technology (BOTDA Brillouin optical time domain analysis) opens new horizons in the field of landslide detection and infrastructure monitoring compared to traditional technologies. The technology uses special tight buffered single mode fibre optic cable for strain and temperature measurement along the fiber. It offers a high resolution of a few microstrains at a spatial resolution of 1m and large application lengths up to 30km.

There are different tools for testing the shear strength (direct shear, simple shear, ring shear or triaxial shear tests), but all of them except the ring shear (Bishop et al., 1971) are not able to run tests with long displacements (Cornforth, 2005). In order to simulate the shearing process in the creeping landslide, however, it is important to have the possibility of a long shear displacement. Commercially available ring shear devices are difficult to handle and suffer from excessive friction. For such reason a new ring shear apparatus was built in the summer 2006 at the workshop at the IGT according the ASTM international standard (ASTM, 2002) and has been going through some modifications and calibrations. Upon the completion of its development, the ring shear tests will be performed on soil samples from St. Moritz, Gantertal and Braunwald for determining of the residual shear strength.

Allgemeiner Stand der Forschung (Englisch)

The Institute for Geotechnical Engineering has been actively involved over the last 30 years in providing expert service to different communities (for example St. Moritz GR and Leimbach ZH) in the field of creeping landslides. In particular, the Geomechanics Group of Prof. Dr. A. M. Puzrin at IGT is strongly engaged in researching subaerial and submarine landslides (Puzrin and Germanovich, 2003; Puzrin et al., 2004; Puzrin and Germanovich, 2005; Puzrin and Sterba, 2006; Puzrin et al. 2007; Puzrin and Schmid, 2007; Iten et al., 2008; Puzrin et al., 2008). This research has attracted funding from the national competitive research funding agencies (the VSS/ASTRA grant “Road-Landslide Interaction” and the SNF grant “The Mechanisms of Tsunamigenic Landslides”). Three field investigation summer campaigns in the years 2006-2008 in St. Moritz and Gantertal have produced some valuable data for the landslide analysis. Development of the new monitoring techniques (such as a novel Inclino-Deformometermeter, fiber optic strain sensing, etc.) and improvement of the laboratory methods (a new ring shear device) provide an excellent basis for the proposed research.

Projektziele (Deutsch)

Das Hauptziel dieser Forschung besteht darin, ein neues Vorgehen zur Überwachung und Analyse von Kriechhängen, die Verkehrswege gefährden, zu erarbeiten. Dabei stützt sich diese Forschung auf eine frühere Arbeit. Dieses neue Vorgehen soll anschliessend an verschiedenen Kriechhängen in der Schweiz angewandt werden. Neuartige Methoden zur Hangstabilisierung sollen ebenfalls erörtert und Empfehlungen zu deren Anwendung in den untersuchten Gebieten gemacht werden. Die drei Ziele der Forschungsarbeit: Analyse, Überwachung und Stabilisierung, sind direkt miteinander verknüpft. Die Analyse benötigt die Daten der vorgängigen Messungen und erlaubt danach eine Optimierung der Stabilisierungsmassnahmen, deren Erfolg durch Überwachungsmassnahmen verifiziert wird und gegebenenfalls weiter angepasst werden müssen.

Projektziele (Englisch)

The goal of the proposed research is, by building on the previous pilot project, to develop new approaches for the monitoring and analysis of creeping landslides affecting the transportation infrastructure, and applying these new approaches to a number of Swiss landslides. Novel approaches to the landslide stabilization will be also explored, and recommendations for their application to the particular landslides will be made. The three goals of this research: analysis, monitoring and stabilization are closely interconnected. Analysis requires monitoring data, and allows for the optimization of the stabilization measures, whose effectiveness has to be in turn confirmed by the monitoring.

Forschungsplan (Englisch)

First year (Milestone 1)

The further development of the IDM will be accomplished so that the IDM can be used in the following years as a reliable “pressure” measurement tool (Task 1). On the same time the further development of the FO landslide monitoring techniques will be finished to improve the results and the interpretation of the FO measurements for the following years (Task 2). The development of chemical and biological stabilization techniques will be concluded in respect of possible application for the researched landslides (Task 3). The first results and recommendation based on the field and laboratory tests as well as on the analytical and numerical models for the “Brattas” landslides will be formulated (Task 4).

Graphik 1

Second year (Milestone 2)

The results of the field and laboratory tests, the analytical and numerical models for the three landslides “Combe Chopin”, “Braunwald” and “Ganter” will lead to conclusions and recommendations with respect of their different boundary conditions (Task 5 - 7).

Graphik 2

Third year (Milestone 3)

In consideration of the previous landslides the field and laboratory tests, as well as the analytical and numerical models for the last two landslides “Via Laret” and “Leimbach” will formulated to conclusions and recommendations (Task 8 - 9). All results of the previous tasks will be considered for the general conclusions and recommendations with respect to the landslide stabilization and hazard mitigation in an attempt to reduce the damage to the infrastructure and economy (Task 10).

Graphik 3

Final Report and Project Evaluation

In the last step the results from all previous tasks with conclusions and recommendations will be summarized in the final report. Additional an extended summary in German will be added to the final report. Recommendations with respect to further research programs in the obeserved field will be formulated.

Graphik 4

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• VSS 2010 502 Graphik 1 bis 4.pdf [PDF] 108 kB

Umsetzung und Anwendungen (Englisch)

Based on the results of the proposed research the conclusions and recommendations will be made with respect to the long term behaviour of the studied landslides and their potential stabilization. Proper procedures for landslide monitoring and analysis considering the applicability of novel sensor technologies as well as novel chemical and biological stabilization techniques will lead to more efficient road infrastructure monitoring and maintenance in favour of the owners and community.

Berichtsnummer (Deutsch)

1502

Berichtsnummer (Englisch)

1502

Literatur (Englisch)

Anderson, J. E. (1992), “Determination of water surface temperature based on the use of thermal infrared multispectral scanner data”, Geocarta International, 3, 3-8

ASTM international (2002), “Standard test Method for Torsional Ring Shear Test to Determine Drained Residual Shear Strength of Cohesive Soils”, Designation: D 6467-99, Annual Book of ASTM Standards, Vol 04.08

Akbar, A. and Clark, B. G. (2001), “A Flat Dilatometer to Operate in Glacial Tills”, Geotechnical Testing Journal, Vol. 24, No. 1, 51-60

Bishop, A., Green, G. E., Garga, V. K., Andersen, A., Brown J. D. (1971), “A new ring shear apparatus and its application to the measurement of residual strength”, Géotechnique 21, No. 4, 273-328

Bjerrum, L. (1967), „Progressive failure in slopes of overconsolidated plastic clay and clay shales“, J. Soil Mech. Found. Engng Div. ASCE 93, No. 5, 1-49.

Bollinger, D. (2000), “Ursachenanalyse der Hanginstabilitäten 1999”, Bull. angew. Geol., 5, No 1, 5-38.

Clark, B. G., Chen, C.-C. and Aflaki, E. (1998), “Intrinsic compression and swelling properties of a glacial till” Quarterly Journal of Engineering Geology, 31, 235-246

Cornforth, D. (2005). “Landslides in practice – Investigation, Analysis, and Remedial/Preventative Options in Soils“, Published by john Wiley & Sons, inc., Hobokon, New Jersey, ISBN 0-471-67816-3

Desai, Ch. S., Samantani, N. C., Vulliet, L. (1995) “Constitutive modeling and analysis of creeping slopes“, J. of Geotechn. Engng, Vol. 121, No. 1, 43-56

François, B., Bonnard, L., Laloui, L., Triguero, V. (2007), “Numerical modelling of the hydrological and geomechanical behaviour of a large slope movement: the Triesberg landslide (Liechtenstein)”, Can. Geotech. J. 44: 840-857.

Gens, A. and Hight, D. W. (1979), “The laboratory measurement of design parameters for a glacial till”, Design parameters in geotechnical engineering, Proceedings of the 7^th Eur Conf Soil Mech Found Engng, Brighton, Vol. 2, 57-65

Gillies, R. R. and Carlson, T. N. (1995), “Thermal remote sensing of surface soil water content with partial vegetation cover for incorporation into climate models”, Journal of Applied Meteorology, 34, 745-756

Huan, A.-B., Jiming, M., Baishan, Z., Xiaoguo, W., Jingang, C., and Yen-Te, H. (2005), “Ground Movement Monitoring Using an Optic Fiber Bragg Grating Sensored System”, 17^th International Conference on Optical Fibre Sensors, May 23–27 2005, Bruges, Belgium

Inaudi, D. and Glisic, B. (2005), “Application of distributed Fiber Optic Sensing for SHM”, 2^nd International Conference on Structural Health Monitoring of Intelligent Infrastructure (SHMII-2’2005), November 16-18 2005, Shenzhen, China

Inaudi, D. and Glisic, B. (2007), “Overview of Fiber Optic Sensing Technologies for Geotechnical Instrumentation and Monitoring”, Geotechnical News, September 2007

Iten, M., Puzrin, A. M., Schmid, A. (2008), “Landslide monitoring using a road-embedded optical fiber sensor” in Smart Sensor Phenomena, Technology, Networks, and Systems 2008, edited by Wolfgang Ecke, Kara J. Peters, Norbert G. Meyendorf, Proceedings of SPIE Vol. 6933 (SPIE, Bellingham, WA 2008) 693315.

Iten, M., Schmid, A., Hauswirth, D. and Puzrin, A. M. (2009), “Defining and monitoring of landslide boundaries using fiber optic systems“, Proc. Int. Symp. on prediction and simulation methods for geohazard mitigation, Kyoto, 451-456.

Labuz, J. F. and Theroux, B. (2005), “Laboratory Calibration of Earth Pressure Cells”, Geotechnical Testing Journal, Vol. 28, No. 2, 1-9

Liu, J.-K., Wong, Ch.-Ch., Huang, J.-H. and Yang, M.-J. (2002), “Landslide-Enhancement images for the Study of Torrential-Rainfall landslides”, Proceedings of the 23^rd Asian Conference on Remote Sensing (ARCS’2002), November 25-29 2002, Kathmandu, Nepal

Long, M. and Menkiti, C. O. (2007), “Geotechnical properties of Dublin Boulder Clay”, Geotechnique 57, No. 7, 595-611

Miura, K., Otsuka, N., Kohama, E., Supachawarote, Ch., Hirabayashi T. (2003), “The size effects of earth pressure cells on measurement in granular materials”, Japanese Geotechnical Society, Soils and Foundations, Vol. 43, No. 5, 133-147

Ohno, H., Naruse, H., Kihara, M. and Shimada, A. (2001), “Industrial Applications of the BOTDR Optical Fiber Strain Sensor”, Optical Fiber Technology, Vol. 7, No. 1, 45-64

Powell, J. J. M. and Butcher, A. P. (2003), “Characterisation of a glacial clay till at Chowden, Humberside”, Characterisation and Engineering Properties of Natural Soils, Vol. 2, 983-1020

Puzrin, A. M. and Germanovich, L. (2003), “Shear Band Propagation in an Infinite Slope”, In 16^th Engineering Mechanics Conference, ASCE, Seattle, USA

Puzrin, A. M. and Germanovich, L. (2005), “The growth of shear bands in the catastrophic failure of soils”, In Proceedings of the Royal Society A, Vol. 461, 1199-1228, London, UK

Puzrin, A. M., Germanovich, L. and Kim, S. (2004), “Catastrophic Failure of Submerged Slopes in Normally Consolidated Sediments“, Geotechnique 54, No. 10, 631-643

Puzrin, A. M., Messerklinger, S. and Schmid, A. (2008), “The in-situ stiffness of the sliding layer in a creeping landslide“, In Proceedings of the ISAtlanta 2008, September 21-24 2008, Atlanta, USA

Puzrin, A. M. and Schmid, A. (2007), “Trivec measurements in the inverse analysis of the long-term stability of a constrained landslide“, Proceeding of the 7^th international symposium on field measurements in Geomechanics, edited by Jerry DiMaggio, P. E., Peter Osborn

Puzrin, A. M. and Sterba, I. (2006) “Inverse long-term stability analysis of a constrained landslide.” Geotechnique, 56, No. 7, 483–489.

Puzrin, A. M., Sterba, I., Schmid, A., Messerklinger, S. (2007), “Der Schiefe Turm von St. Moritz – Geotechnische Aspekte von Bauten in einem aktiven Erdrutsch“, Jahresbericht 2006 des Departementes Bau, Umwelt und Geomatik der ETH Zürich

Terzaghi, K. (1936), “Stability of slopes of natural clay“, Proc. 1^st Int. Conf. Soil Mech. Found. Engng, Cambridge, MA 1, 161-165.

Tesarik, D. R., Seymour, J. B., Williams, T. J., Martin, L. A., Jones F. M. (2006), “Temperature corrections to earth pressure cells embedded in cemented backfill.”, report of investigations 9665, U.S. Department of Health and Human Services, Centers for Disease Control and Prevention, National Institute for Occupational Safety and Health, Spokane Research Laboratory, Spokane, WA

Schindler, C. (1982), “Problemreiche Hinterlassenschaften, Geologie und Wasserverhältnisse in Braunwald”, Separatdruck aus dem Neujahrsboten 1982 für das Glarnerland.

Schlüchter, Ch. (1988), “Instabilities in the area of St. Moritz, Switzerland”, Proceeding 5th Int. Symposium on Landslides, Lausanne, Switzerland

Schmid, A. (2006). “Kriechhang Ganterbrücke – Modellierung eines Kriechhanges” Diplomarbeit WS 2005/2006, IGT, ETHZ

Schwager, M. V., Schmid, A. and Puzrin, A. M. (2009). ”Inclinodeformometer : A novel device for measuring earth pressure in creeping landslides”, Proc. Int. Symp. on prediction and simulation methods for geohazard mitigation, Kyoto, 479-484.

Skempton, A. W. (1964), “Long-term stability of clay slopes“, Géotechnique 14, No. 2, 77-102.

Vulliet, L., Hutter, K. (1988), “Set of constitutive models for soils under slow movement”, J. of Geotech. Engng Vol. 114, No. 9, 1022-1041