In many engineering applications, it is important to determine both effective rock properties and the rock behavior which are representative for the problem's in situ conditions. For this purpose, ...rock samples are usually extracted from the ground and brought to the laboratory to perform laboratory experiments such as consolidated undrained (CU) triaxial tests. For low permeable geomaterials such as clay shales, core extraction, handling, storage, and specimen preparation can lead to a reduction in the degree of saturation and the effective stress state in the specimen prior to testing remains uncertain. Related changes in structure and the effect of capillary pressure can alter the properties of the specimen and affect the reliability of the test results. A careful testing procedure including back-saturation, consolidation and adequate shearing of the specimen, however, can overcome these issues. Although substantial effort has been devoted during the past decades to the establishment of a testing procedure for low permeable geomaterials, no consistent protocol can be found. With a special focus on CU tests on Opalinus Clay, this study gives a review of the theoretical concepts necessary for planning and validating the results during the individual testing stages (saturation, consolidation, and shearing). The discussed tests protocol is further applied to a series of specimens of Opalinus Clay to illustrate its applicability and highlight the key aspects.
The real-time detection of potentially destructive water, earth and snow mixtures such as debris flow and avalanches is a topic of growing interest to mitigate the risk in anthropized areas such as ...the Alpine region. In view of this, a new cutting-edge debris flow and avalanche detection system, called OPTIALP, was developed. The proposed system exploits the polarization variations induced on the fiber by mechanical vibrations, for the automatic detection along their propagation path of potentially destructive snow and soil-water mixtures. One of the main values-add of the OPTIALP system is the “quasi distributed” and spatially continuous detection along the whole fiber which improves the current monitoring technologies relying on “discrete” monitoring points and sensors. The OPTIALP system was designed and thoroughly tested in the laboratory environment by means of a specific setup. Over 650 tests were carried out and a new signal processing algorithm developed in Matlab environment capable to interpret the data acquired was created. The results showed that the OPTIALP system is able to correctly identify the signals produced by lab-scale mass movements.
Climate change is already being felt in Europe, unequivocally affecting the regions’ geo-structures. Concern over this is rising, as reflected in the increasing number of studies on the subject. ...However, the majority of these studies focused only on slopes and on a limited geographical scope. In this paper, we attempted to provide a broader picture of potential climate change impacts on the geo-structures in Europe by gathering the collective view of geo-engineers and geo-scientists in several countries, and by considering different geo-structure types. We also investigated how geo-structural concerns are being addressed in national adaptation plans. We found that specific provisions for geo-structural adaptation are generally lacking and mainly come in the form of strategies for specific problems. In this regard, two common strategies are hazard/risk assessment and monitoring, which are mainly implemented in relation to slope stability. We recommend that in future steps, other geo-structures are likewise given attention, particularly those assessed as also potentially significantly affected by climate change. Countries considered in this study are mainly the member countries of the European Large Geotechnical Institutes Platform (ELGIP).
Underground geotechnical structures, such as deep and shallow foundations, diaphragm walls, tunnel linings and anchors are being increasingly employed as energy geostructures to exchange heat with ...the ground by installing absorber pipes into the structural elements. This paper focuses on the application of this technology to reinforced concrete diaphragm walls used for construction of underground car parks, basements and metro stations, with the purpose of heating and cooling the adjacent buildings. Preliminary numerical modelling allowed optimising the geothermal plant design of the diaphragm wall. Then its energy efficiency is investigated through finite element thermo-hydro coupled analyses together with the effects of the thermal activation on the surrounding soil. Finally, finite difference thermo-mechanical analyses are used to study the mechanical effects induced by the thermal activation.
•Thermal and mechanical aspects of energy walls are discussed.•The horizontal configuration of pipes geometry allows maximising the heat exchange.•Heat exchange between 20 and 25 W/m2 with static ground water.•Heat exchange between 40 and 50 W/m2 with favourable groundwater flow.•Bending moment increase up to 16% due to thermal activation.
•FE models were run to study energy efficiency and sustainability of energy tunnels.•The energy tunnel system allow to exchange between 53 to 74W/m2 of tunnel lining.•Energy tunnels are effective and ...innovative ground heat exchangers.•Influence on the ground is limited if the system is used both in winter and summer
Deep and shallow foundations, diaphragm walls, tunnel linings and anchors are being increasingly employed as energy geostructures in Europe and all around the world. Besides being constructed for their primary structural role, they are equipped to be able to exchange heat with the ground and supply thermal energy for heating and cooling of buildings and de-icing of infrastructures. This technology can play a fundamental role in the current challenge of addressing the increasing need for clean and renewable sources of energy. This paper investigates the possibility of thermal activation of a new section under construction of the Metro Torino line 1 (Italy) to heat and cool adjacent buildings. The design and optimization of the geothermal plant, the quantification of the exploitable heat and the assessment of the eventual consequences on the surrounding ground are here discussed. For this purpose, thermo-hydro finite element analyses, able to capture the key aspects of the problem, were conducted. A 3D model is devoted to study the efficiency of the system, reproducing one ring of the instrumented tunnel segmental lining, while a 2D large scale model of the Torino aquifer is conceived to investigate the sustainability of the technology in terms of effects on the surrounding environment. Based on the results of the computations, it can be anticipated that, thanks to the favorable underground water flow conditions in Torino, the system would allow 53 and 74W per square meter of tunnel lining to be exchanged during winter and summer respectively.
Questo documento presenta le Linee Guida per la gestione sostenibile delle venute d’acqua e del calore geotermico nelle gallerie, elaborate dal Gruppo di Lavoro GESTAG (GEstione SosTenibile delle ...Acque nelle Gallerie), istituito il 20/06/2012 dal Comitato Italiano dell’Associazione Internazionale degli Idrogeologi. Il documento affronta e descrive obiettivi, metodi e casi di studio, ciascuno dei quali richiede di adottare misure tecniche di vario tipo, illustrate nei capitoli seguenti, come studi idrogeologici, modelli predittivi degli impatti, soluzioni tecnologiche di contenimento del drenaggio e di captazione, recupero e valorizzazione delle risorse intercettate, monitoraggi. Sono affrontati anche i così detti temi non tecnici, come la comunicazione, poiché è ormai noto che l’accettabilità sociale di una galleria influenza direttamente la sua sostenibilità economica e finanziaria, per gli effetti che può avere sui tempi di realizzazione e sui costi delle compensazioni. Sulla base delle diverse esperienze dei componenti del Gruppo di Lavoro GESTAG, si è optato per una suddivisione in 11 temi principali, in particolare, in ciascuno dei capitoli successivi a quello introduttivo vengono trattati rispettivamente: Capitolo 2: l’importanza del ritorno di esperienza proveniente da gallerie già scavate, le banche dati disponibili e i criteri di analisi dei dati pregressi; Capitolo 3: come realizzare lo studio idrogeologico di una galleria, la relazione con il modello geologico, le metodiche da adottare nelle differenti fasi del progetto, che sono state distinte in ante-operam, in corso d’opera e post-operam; Capitolo 4: il tema degli impatti che il drenaggio in galleria può avere sull’ambiente circostante, le analisi che devono essere svolte e gli strumenti da adottare per la gestione del rischio, infine gli interventi per la mitigazione degli impatti; Capitoli 5 e 6: le metodiche di progettazione per la valorizzazione rispettivamente delle acque drenate in galleria e del calore; Capitolo 7: i prodotti chimici che vengono utilizzati in fase di scavo per il sostegno e il miglioramento del terreno, e la loro compatibilità con l’utilizzo delle acque drenate; Capitolo 8: i criteri di monitoraggio delle acque in un progetto di galleria; Capitolo 9: la comunicazione, il rapporto con i territori e l’analisi di casi pregressi, nonché una guida sulle buone pratiche da adottare; Capitolo 10: una panoramica sulla normativa europea ed italiana in tema di valutazione di impatto ambientale, monitoraggio e scarichi delle acque drenate; Capitolo 11: la bibliografia ragionata inerente l’argomento trattato, che include pubblicazioni tecnico scientifiche, normative di riferimento e risorse web.
Background
Rockfall events are one of the most dangerous phenomena that often cause several damages both to people and facilities. During recent years, the scientific community focused the attention ...at evaluating the effectiveness of seismological methods in monitoring these phenomena. In this work, we present a quick and practical method to locate the rebounds of some man-induced boulders falls from a landslides crown located in the Northern Apennines (Central Italy). The reconstruction of the trajectories was obtained by means of back analysis performed through a Matlab code that takes into account both the DEM (Digital Elevation Model) of the ground, the geotechnical-geophysical characteristics of the slope and the arrival times of the seismic signals generated by the rock impacts on the ground.
Results
The localization results have been compared with GPS coordinates of the points and videos footage acquired during the simulations, in order to assess the reliability of the method. In most cases, the retrieved impact points match with the real trajectories, showing a high reliability. Furthermore, four different cases have been identified as a function of the geomechanical, geophysical and morphological conditions. Due to the latter ones, in some case it was necessary to assume different values for the propagation velocity of the elastic waves in the ground, here assumed to be isotropic and homogeneous.
Conclusions
This work aims at evaluating the effectiveness of a quick and practical method to locate rockfall events using a small-aperture seismic network. The obtained results indicate that the technique can provide quantitative information about the area most prone to impact of detached blocks. The method still presents some uncertainty, but reducing some of the approximations (e.g. by better constraining the velocity model), it could lead to prompt and more accurate results, easily applicable to hazard estimates.
This paper is to contribute to the understanding of the behaviour of tunnels in swelling ground. An Italian case study of a tunnel, collapsed due to swelling of a stiff clay, is taken as an example. ...The stress paths during excavation of elements of ground around the opening are computed in order to evidence the significant difference to that reproduced by usual swelling tests in the laboratory. An innovative triaxial testing procedure is developed and the stiff-clay tested. A numerical simulation of the swelling phenomenon induced by the excavation of the tunnel, based on the experimental results obtained, is then compared to site observations.
The first application of ground-based interferometric synthetic-aperture radar (GBInSAR) for slope monitoring dates back 13 years. Today, GBInSAR is used internationally as a leading-edge tool for ...near-real-time monitoring of surface slope movements in landslides and open pit mines. The success of the technology relies mainly on its ability to measure slope movements rapidly with sub-millimetric accuracy over wide areas and in almost any weather conditions. In recent years, GBInSAR has experienced significant improvements, due to the development of more advanced radar techniques in terms of both data processing and sensor performance. These improvements have led to widespread diffusion of the technology for early warning monitoring of slopes in both civil and mining applications. The main technical features of modern SAR technology for slope monitoring are discussed in this paper. A comparative analysis with other monitoring technologies is also presented along with some recent examples of successful slope monitoring.
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