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Abstract In deep tunnels the knowledge of in-situ rock temperatures is of great importance, e.g. for the design of ventilation and cooling. A finite element model simulation technique for rock temperature prediction is described. The method handles complex thermal/hydraulic characteristics, pronounced topographic relief, deep groundwater circulation, transient coupled heat/fluid transfer, uplift/erosion and thermal history. During tunnel excavation the rock temperatures were measured. The procedure has been verified by comparing measurement and prediction under Alpine conditions, namely in the Gotthard base tunnel, Switzerland and the Koralm Tunnel, Austria: The agreement is well, within ±15%. Reliable simulations call for a solid data base; e.g. surface temperatures, basal heat flow and uplift/erosion patterns must be determined beforehand. The range of geothermal and hydrogeologic properties should be known. Only temperature data along the planned tunnel trace below the highest cover, preferably measured in well positioned boreholes, enable proper model calibration. 1 Introduction The distribution of in-situ rock temperatures in deep tunnelling is of predominant importance in planning, construction and operation, e.g. for the design of ventilation and cooling. The determination of rock temperatures along a planned tunnel trace at depth is especially a demanding task in mountainous terrain. The rock temperature field within a mountain massif is the result of heat transport processes (heat conduction and advection) and depends on several boundary conditions (e.g. surface temperature, basal heat flow) as well as on numerous parameters (e.g. 3-D topography, distribution of geological units/of thermal conductivity, water circulation pattern/distribution of hydraulic conductivity), along with transient processes like uplift/erosion or paleoclimatic changes. The complexity of these parameters calls for a correspondingly flexible and efficient calculation method. Only advanced numerical model simulation can cope with these manifold requirements. The development and application of such a modelling approach is presented for the Gotthard Base Tunnel (GBT), Switzerland, combined with its verification based on actual measurements along the excavated tunnel.
- Production and Well Operations > Well & Reservoir Surveillance and Monitoring > Production logging (1.00)
- Reservoir Description and Dynamics > Reservoir Characterization (0.89)
- Reservoir Description and Dynamics > Formation Evaluation & Management (0.88)
- Data Science & Engineering Analytics > Information Management and Systems (0.85)
Numerical Analysis of Laboratory Heating Experiments on Claybased Material
Wang, Xuerui (Federal Institute for Geosciences and Natural Resources (BGR)) | Shao, Hua (Federal Institute for Geosciences and Natural Resources (BGR)) | Hesser, Jürgen (Federal Institute for Geosciences and Natural Resources (BGR)) | Zhang, Chun-Liang (Gesellschaft für Anlagen- und Reaktorsicherheit (GRS)) | Wang, Wenqing (Helmholz Centre for Environmental Research (UFZ)) | Kolditz, Olaf (Helmholz Centre for Environmental Research (UFZ))
Abstract This paper presents coupled thermo-hydro-mechanical (THM) simulations of the laboratory heating experiments on the Callovo-Oxfordian (COX) clay and on the MX-80 bentonite. Both materials are commonly investigated as important components in the multiple barrier system for the disposal of high-level radioactive waste (HLW). The models are based on the Finite-Element (FEM) program OpenGeoSys (OGS) (Kolditz et al. 2012). A non-isothermal multiphase flow model was applied to take account of both the liquid and gas phase, the phase change and vapour diffusion. The transversal isotropic properties of COX is considered by applying anisotropic THM parameters. A pore pressure dependent permeability model has been developed to explain the experimental observations. The dependency of thermal conductivity on saturation degree and the temperature effect on water retention behaviour have been considered in the modelling to analyse the experimental data on the MX-80. The strong swelling and shrinkage behaviour of both materials were analysed with a swelling pressure model. 1 Introduction Heat-emitting is an important issue in the disposal of HLW. This paper concentrates on the development of numerical model to analyse the thermal effect on the hydromechanical process. To validate the model, simulations of two laboratory heating experiments have been carried out. One is a short-term heating experiment on Callovo-Oxfordian clay which was carried out by GRS, Germany in 2010 (Zhang et al. 2010). Another is a long-term heating and hydration experiment on MX-80 pellets that is being performed by CIEMAT (Centro de Investigaciones Energéticas, Medioambientales y Tecnológicas) since 2012 (Villar 2012). Both laboratory experiments have provided numerous database for the numerical analysis. Based on the experimental observations, several numerical approaching have been developed to get a better interpretation of the measurements. The developed models could be regarded as important tools for the structured framework of the interpretation and analysis of the coupled THM process in the repository of HLW from small to large scale.
- Geology > Geological Subdiscipline > Geomechanics (0.74)
- Geology > Mineral (0.56)
- Reservoir Description and Dynamics > Reservoir Fluid Dynamics > Flow in porous media (0.52)
- Reservoir Description and Dynamics > Reservoir Characterization > Reservoir geomechanics (0.41)
- Production and Well Operations > Well & Reservoir Surveillance and Monitoring > Production logging (0.37)
- Reservoir Description and Dynamics > Reservoir Fluid Dynamics > Multiphase flow (0.34)
Abstract Recently, early warning systems have gained much more importance in terms of risk management since awareness regarding landslide hazards has increased dramatically. Different instrumentation techniques have used to monitor mass movements. Although all techniques have their own advantages and disadvantages, optical fiber system has certain superiority over others with an incessant data acquisition capability. The main objective of this study is to monitor slope movement regardless of lithology and failure types. Equipment utilized consists of an optical fiber system containing Brillouin Optical Time Domain Reflectometer (BOTDR) and optical fiber cables. The tests show that fiber optical technology could be used as a monitoring tool and is useful in determining slope movement throughout a fiber array. The results of this study are expected to be used in risk assessment studies in hazard prone regions and during the construction and post construction period. 1 Introduction Landslide is one of the most destructive natural hazards in Turkey and around the world (Gökçe et al. 2008). Significance of mass movement studies becomes obvious when the number of landslide occurrences and adversely affected structures are considered. Awareness about these phenomena and the importance given to the concept of risk management has been continuously increasing due to low reoccurrence period of this disaster in a region. Therefore, early warning systems have gained popularity (i.e., Li et al. 2012, Liu et al. 2010, Pei et al. 2011). According to previous studies, geomorphological parameters, precipitation, groundwater fluctuation, seismicity, daily temperature difference, snowmelt, distribution of geological formations are the main causes of landslides and slope failures. In addition, instability of the slopes formed by the disturbance of the natural stability of the slope via manmade activities increases the level of hazard. There are many techniques use different instrumentation such as inclinometers, tiltmeters, extensometers, and ground based LIDAR to monitor landslides triggered by various effects (Savvaidis 2003 and Pei et al. 2011). Although all of these monitoring techniques have their own advantages and disadvantages, optical fiber technology became prominent owing to the characteristics of easy data transfer capability, high transmission speed, lightweight, resistance to environmental impacts and electromagnetism; and, simultaneous monitoring capability (Wang et al. 2008). Especially, capability of incessant data acquisition needed for early warning systems is a significant property. Superiority of optical fibers on these subjects makes their use reasonable for landslide monitoring as well as any displacement related engineering structure like dams, road cuts, mines and buildings.
- Europe (1.00)
- Asia > Middle East > Turkey (0.53)
- Geology > Geological Subdiscipline (0.48)
- Geology > Structural Geology (0.47)
- Data Science & Engineering Analytics > Information Management and Systems (1.00)
- Reservoir Description and Dynamics > Reservoir Characterization > Exploration, development, structural geology (0.54)
- Production and Well Operations > Well & Reservoir Surveillance and Monitoring > Production logging (0.49)
Abstract In the Mont Terri rock laboratory, nearly 20 years of experience with long-term monitoring could be gained. Long-term monitoring under harsh conditions, such as enhanced pressure, temperature and corrosive chemical environment is one of the key issues of the Mont Terri Project research program. Two experiments specifically focusing on monitoring are presented. Numerous long-term pressure time series are available, from overpressure systems, where the pressure transducer is installed at the borehole head. Long-term stability of pressure transducers proved to be very good. The measurement of temperature is regarded as a simple parameter to be measured; however, long-term experience with conventional temperature sensors has revealed their vulnerabilities. Long-term performance of different fiber optical sensors is evaluated in a further borehole. The three-year dataset clearly highlights the importance of independent conventional parameter control and the possibility for later recalibration. 1 Introduction Since 1996, numerous experiments have been conducted in the Mont Terri rock laboratory, located in the northwestern part of Switzerland. Monitoring and especially long-term monitoring of different parameters under harsh conditions in argillaceous rocks with highly saline pore waters, e.g. up to 20,000 mg/l of solutes, Cl/Br -ratios similar to recent sea water, anaerobic conditions, negative redox potential, and subjected to increased pressure and temperature conditions is one of the key issues of the research conducted in the Mont Terri rock laboratory. The research on monitoring is closely linked to the Swiss concept for a HLW repository, which foresees a Pilot repository located close to the main repository, where a well-defined part of HLW can be monitored over decades in the early phase of repository evolution. Experience about the behavior and long-term performance of different kinds of sensors could be gained from numerous experiments. Common parameters measured in the 130 experiments at Mont Terri rock laboratory, of which 46 are currently running, are pore water pressure, total pressure, temperature, humidity, deformation, climatic data, geochemical parameters, such as pH, Eh, electric conductivities, corrosion rates, gas concentrations, seismic and geo-electric signals. There are several experiments yielding datasets of up to nearly 20 years duration. From these experiments three examples, where monitoring and data evaluation including interpretation are of great importance are presented and discussed. The results and experience from numerous additional experiments are finally summarized, building the basis for future instrumentations of underground facilities.
- Geology > Geological Subdiscipline > Geochemistry (0.54)
- Geology > Geological Subdiscipline > Geomechanics (0.32)