Engineering Geology

In the frame of risk analysis the knowledge of the existence and
location of hazard zones is of major importance. Besides the
traditional deterministic and statistic methods for automatic
hazard analysis, the use of artificial Neural Nets is a new and
interesting approach. The advantage of Neural Nets is their
ability to handle non­linearities as well as large and complex
data sets.
Several types of neural models have been developed and tested for landslide recognition. It is a characteristic of these
Neural Nets that they are capable to recognize different types
of mass movements. Not only the landslide itself but also the
complete area influenced by mass movements. Various strategies have been pursued to develop the Neural Nets. Besides the standard nets for landslide recognition, also nets switched in line and nets using the MTL­approach have been trained and tested. The tests demonstrated that the different net models de­velop different specializations.
The best nets for landslide recognition classified up to 86% of
the test sites in the Eastern Alps correctly. The tests showed
that these nets are especially qualified for the detection of
landslides caused by erosional and mount torrent processes.
Using query techniques it has been possible to further improve
the results up to 89%.

Keywords: risk analysis, hazard analysis, landslide recognition,
landslide, neural net, MLP, feed forward net, RPROP, MTL,
Salzkammergut, Stambach, Zlambach.

Im Rahmen von Risikoanalysen spielt die Kenntnis über das
Vorhandensein und die Lage von Gefahrenherden eine ganz
wesentliche Rolle. Neben den bisher bekannten deterministischen und statistischen Verfahren können auch künstliche Neuronale Netze zur automatischen Gefahrenerkennung genutzt werden. Der Vorteil Neuronaler Netze liegt in ihrer Fähigkeit begründet, nichtlineare Zusammenhänge gut darzustellen und mit sehr großen Datenmengen gut zurechtzukommen.
Für die Erkennung von Hangrutschungsgebieten sind mehrere neu­ronale Modelle entwickelt und untersucht worden. Eine
Besonderheit ist, dass die Netze verschiedene
Massenbewegungstypen erkennen können. Es wird auch nicht nur die Rutschung sondern der ganze Einflussbereich der Massenbewegung erkannt. Bei der Entwicklung der Netze sind verschiedene Strategien verfolgt worden. Neben Netzen zur Rutschungserkennung sind in Reihe geschaltete Netze und nach dem MTL-Ansatz trainierte Netze untersucht worden. Dabei hat sich gezeigt, dass die einzelnen Modelle z.T. unterschiedliche Spezialisierungen entwickeln.
Bei Versuchen mit den Netzen Rutschungen in Testgebieten in den Ostalpen zu erkennen, haben die besten Netze bis zu 86% der Gebiete richtig klassifiziert. Dabei hat sich gezeigt, dass die
Netze Massenbewegungen in Zusammenhang mit Wildbach­ und
Erosionsprozessen besonders gut erkennen können. Durch gezielte Abfragen konnten die Ergebnisse auf bis zu 89 % erhöht werden.

Schlüsselwörter: Risikoanalyse, Gefahrenerkennung, Rutschungser­kennung, Massenbewegung, Rutschung, Neuronales Netz, MLP, Vor­wärtsgerichtete Neuronale Netze, PROP, MTL, Salzkammergut, Stambach, Zlambach.

Today geology faces new challenges but also great chances brought on by the increased use of digital information. On one hand in the last decade the increase in data volume has been enormous, on the other hand the data sources are still neither homogeneous nor widely distributed. Furthermore often the only available data for a survey were acquired for completely different purposes. Especially when tasks become more complex, the usage of distributed not homogeneous data is essential and leads to considerable problems.
One possible solution is the development of data warehouses, integrating all available and needed data. The disadvantage of this concept is a reduced flexibility and the investments to build up and run this data environment. Another solution is provided by recent developments in Geoinformatics: the use of Spatial Data Infrastructures (SDI) for management of huge amounts of spatially related data. In contrast to the data integration approach, SDIs foster the re-use of already existing data inventories for future uses that are not known yet. The approach aims at just-in-time integration of data in a distributed computing environment. The main building block of any SDI is the web service technology, an industrial standard in the field of Information Technology (IT).
Most tasks related to engineering geology are dependent on a broad variety of data, not necessarily assembled in one place In this paper problems resulting from this fact will be discussed and shown where engineering geologist may profit from the application of SDI. Typical approaches for the usage will be shown and an established case study (groundwater vulnerability assessment) is discussed to demonstrate the capabilities the potential of this technique in Engineering Geology.

Besides precipitation triggered landslides, a major thread from landslides is related to earthquake triggered landslides, which account for the majority of catastrophic landslides. This fact is complicated due to the progressive development of urban areas and infrastructure, the dependency of our society on a functioning infrastructure and an increasing number of endangered objects in the affected areas. Therefore there is a need to improve basic understanding of the technical, financial and social risks posed by earthquakes triggered landslides. Furthermore basic understanding of processes and cascading hazards related to earthquake triggered landslides must be improved. For the past two decades an increasing number of landslide warning systems are developed and applied for general public and industrial purposes. On the other side earthquake triggered landslide warning and monitoring has made very little advances and is still under development. Resent research in the area of sensor network development focus on the application of micro sensors (MEMS) in ad hoc wireless sensor networks operated in an interoperable spatial data infrastructure (SDI) according to the sensor web enablement (SWE) guidelines of the OGC (Open Geospatial Consortium) for real-time monitoring of landslides like the SLEWS – Sensor based Landslide Early Warning System. The SLEWS sensor nodes provide next to motion detection also a 3D acceleration data to evaluate direction and value of the peak acceleration. This information can be used in an event case both to monitor endangered slopes or critical infrastructures and to initiate warnings to trigger e.g. rail or road blocks. Furthermore the data from the sensor network can be provided in real-time for shake or alert maps via standardized interfaces.

The ground freezing construction technique is one of the most effective and widely applied site construction methods in soft soil areas, like Shanghai. Some elevation-inclined refrigeration pipes are arranged for the artificial freezing excavation of the Pudong-side first-storey connection aisle, which is designed to connect two adjacent tunnel lanes of Shanghai East-Fuxing-Road tunnel project. No advanced research results could be found for computing the temperature field of tunnels and aisles frozen with inclined refrigeration pipes. Anyhow the computation of the relevant temperature field is of high importance for the safe and economical excavation of the above-mentioned aisle. In this paper, a method for computing the aisle temperature field using 3D FEM is given, and the computation accuracy is verified by contrasting the computed and site measured results. The back propagation neural networks are also applied to the temperature prediction using self-developed Neural Network-Expert System software, the predicted results are also very satisfactory. The mechanism during freezing and aisle excavation will be discussed on the basis of 3D FEM simulation. The authors believe that studying the parameter-sensitivity of temperature field is very important for the optimum selection of parameter values. So, in this paper, the parameter-sensitivity of temperature field is also discussed. In order to obtain the optimum frozen wall thickness, the relation between the frozen wall thickness and the initial freezing brine temperature is studied. At the end, an excavation pre-control plan is proposed by means of fuzzy logic theory for improving the excavation safety. The research result of the current paper is very helpful for projects that will be excavated by freezing construction technique.

The clay-electrolyte system is characterized by the interaction between ions on the surface of the clays. The most important theory to compute the potential at surface and potential distribution are the ones of Gouy and Stern. The following paper deals with the quantitative computation of the potential at the surface for pure kaolinite and smectite mixed with water, 1 M NaCl and pure ethanol. Besides, an attempt has been made to compute the potential distribution by means of the Stern model.

The Lake Ohrid Basin in FYROM (Former Yugoslav Republic of Macedonia) and Albania meets all criteria of an active, seismic landscape: linear step-like fault scarps in the landscape and under water within the lake. Post-glacial (or Late Pleistocene) bedrock fault scarps at Lake Ohrid are long-lived expressions of repeated surface faulting in tectonically active regions, where erosion cannot outpace the fault slip. Other morphotectonic features are wind gaps, wineglass-shaped valleys and triangular facets, which are well preserved. Generally, the faults and fault scarps are getting younger towards the basin centre, as depicted on seismic and hydroacoustic profiles. Additionally, mass movement bodies within the lake and also onshore (rockfalls, landslides, sub-aquatic slides, homogenites, turbidites) are likely to have been seismically triggered. These morphotectonic observations are in line with focal mechanisms of earthquakes in the greater Lake Ohrid area. We investigated the neotectonic history and tectonic geomorphology of the Lake Ohrid Basin by means of an integrated multidisciplinary approach, using tectonic geomorphology and a variety of geophysical and remote sensing methods.

Early warning systems are becoming one of the main pillars of disaster prevention in natural hazards
especially where mitigation strategies are not realizable. Therefore, the call for multi-hazard early warning systems and improvement of monitoring of natural hazards is steadily growing. However, data gathering (generation) through sensor integration as well as system independent supply of information from early warning networks are of particular challenge. Because very complex information and warning chains have to be served for, standardization and interoperability plays an important role for all organizations and infrastructures being involved. The SLEWS project investigates the complete information chain, starting from data gathering using wireless sensor networks via information processing and analysis to information retrieval. This is demonstrated for landslides and mass movements. The proposed approach adds especially to the funding target of mobile, cost-reduced and easy deployable measurement systems, as well as the modern information systems under consideration of interoperability and service orientated architecture concepts. The proposed wireless network provides the basis for applying further techniques like sensor fusion, identification of malfunctions or errors. The obtained geodata is processed according to the requirements of particular users and can be provided for use in a local or regional as well as global information structure. Interfaces will be created, which make a mobile and flexible adaptation or integration of geodata possible. Thus, it is ensured that the early warning system reaches the spectrum of potential users and provides a maximum flexibility.

Charlemagne (Charles the Great) placed the centre of his kingdom during Carolingian times in Aachen, Germany (Aquisgrana). This medieval period and his regency are associated with a period of extensive constructions in Aachen, including the Carolingian part of the Aachen cathedral. The cathedral was the first building in Germany to join the UNESCO World Heritage list. The foundations and construction ground of the cathedral were excavated during recent archaeological and geotechnical investigations. The cathedral is founded on pillars and piles in Devonian blue limestone and shale, covered by Pleistocene loess sediments. Remains of Roman buildings, such as thermae, are situated below this part of the cathedral. The pillars are connected by up to 5 m deep foundation walls and are up to 2.4 m thick. Even though information about the construction site is important for the assessment of structural health and remediation measures, it is often rare for old historical buildings. Documentations from construction time concentrate on the construction progress and financial aspects. Detailed descriptions on the foundation ground and techniques are usually not preserved. This information is of relevance for assessment of earthquake related structural damages and site effects on construction. Investigations in the course of remediation measures or archaeological surveys fill this information gap. They provide insights in the ancient foundation techniques and can be used for identifying earthquake related phenomena in the construction site. Furthermore, a direct insight into potential seismic effects associated with the ground and building response on seismic shaking becomes possible. In the case of the Aachen cathedral, typical geotechnical investigation methods including drilling and laboratory tests were applied together with GPR measurements to evaluate the construction ground and evaluate potential seismological effects.

In the last years the number of tunnelling projects in Europe increased considerably. Today the most common technique is mechanical heading with tunnel boring machines (TBM). In the course of tunnelling projects, often unexpected problems are encountered due to adhesion between clays and tool surfaces. Unfortunately, there is a lack of knowledge regarding the chemo-mechanical behaviour of the excavated material. As it is well known, the engineering behaviour of fine-grained soils depends mainly on the clay mineralogy of the soil. In first experiments Atterberg limits and vane shear tests have been performed with pore fluids showing different dielectric constants which were added to standard clays. These experiments were performed to investigate and quantify the impact of the dielectric constant of the fluids on the geotechnical properties of the different clay groups. All tests show that the mechanical behaviour is strongly affected by the dielectric constant of the pore fluids. Additionally, electro-osmotic experiments have been performed to investigate the effect of electric charge on the adhesion behaviour of the clay samples in order to reduce the adherence for a certain clay type. The adhesion behaviour of different clays has been also tested in newly developed cone pull-out tests.

Besides precipitation, a major trigger for landslides is earthquake. Landslides triggered by earthquake always cause significant fatalities and economic loss. Therefore it is
needed to improve basic understanding of the technical, financial and social risks posed by earthquakes triggered landslides. Furthermore basic understanding of processes and cascading
hazards related to earthquake triggered landslides must be enhanced. Recent research in the area of real-time monitoring of landslides development focus on the application of micro
sensors (MEMS) in ad hoc wireless sensor networks operated in an interoperable spatial data infrastructure (SDI) according to the sensor web enablement (SWE) guidelines of the OGC
(Open Geospatial Consortium), like the SLEWS-Sensor based Landslide Early Warning System. Apart from motion detection, the SLEWS sensor nodes also provide a 3D acceleration data to evaluate direction and value of the peak acceleration. This information can be used in an event case both to monitor endangered slopes or critical infrastructures and to initiate warnings of rail or road blocks. Furthermore the data from the sensor network can be provided in real-time for shake or alert maps via standardized interfaces. In this paper, through comparison of numerical solutions and real-time data, the mechanical parameters can be inferred by inversion method, which are in turn to determine the safety factor or the
reliability degree of slopes needed in DIN 1054.

Underground coal gasification is currently being considered as an economically and environmentally sustainable option for development and utilization of coal deposits not mineable by conventional methods. This emerging technology in combination with carbon capture and sorptive CO2 storage on the residual coke as well as free-gas CO2 storage in the cavities generated in the coal seams after gasification could provide a relevant contribution to the development of Clean Coal Technologies. Three hard coals of different rank from German mining districts were gasified in a laboratory-scale reactor (200 g of coal at 800 °C subjected to 10 L/min air for 200 min). High-pressure CO2 excess sorption isotherms determined before and after gasification revealed an increase of sorption capacity by up to 42%. Thus, physical sorption represents a feasible option for CO2 storage in underground gasification cavities.

During mechanical tunnel driving, the excavated material often leads to several problems. For example, the sticking of clay in a tunnel boring machine can occur at various surfaces: at the cutting wheel, in the mixing chamber, and in the transport system. Unfortunately, it is presently very difficult to quantify the adhesion by using laboratory tests. Additionally, methods used to address the clogging are still based on empirical attempts without acting on the mineralogical properties of the clays. Atterberg limit determinations and undrained shear tests were performed in order to observe the variation of these simple mechanical properties for smectite-quartz powder mixtures with water and different electrolytes (e.g., NaCl and CaCl2). Additionally, the clogging potential of pure smectite-quartz powder mixtures with water, NaCl, and CaCl2 was quantified by the so-called cone pull-out test. NaCl and CaCl2 solutions reduce the clogging of smectite-quartz mixtures in the laboratory due to a decrease in the liquid limit and plasticity index. This work will help researchers to gain a better understanding of the mechanisms that influence clogging during mechanical tunnel driving in clayey soil sediments, as the effects of different electrolytes on the variation of soil sediment properties.