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Andriani, G. F. (University of Bari Aldo Moro) | Lollino, P. (Research Institute for Geo-Hydrological Protection of Italian National Research Council) | Perrotti, M. (Research Institute for Geo-Hydrological Protection of Italian National Research Council) | Fazio, N. L. (Research Institute for Geo-Hydrological Protection of Italian National Research Council)
This is particularly true for those rocks that are highly sensitive to the interaction with water, as for Very soft porous carbonate rocks belonging to the example the soft porous rocks here examined. It comes Calcarenite di Gravina Formation (upper Pliocene-lower out that hydro-mechanical processes as the water content Pleistocene) crop out extensively in the Apulia region variation, the saturation, the drying-wetting cyclic (South Italy) and, as such, are involved in a huge amount processes, the susceptibility of the rock to weathering of engineering boundary value problems regarding and degradation processes, the direction of propagation building foundations, underground caves and sea cliffs. of weathering, etc., strongly affect the mechanical In particular, sinkholes affecting man-made caves behaviour of these materials and therefore they deserve interacting with urban areas and transport infrastructures to be investigated. In this perspective, concerning the as well as collapses of sea cliffs affect soft calcarenite same calcarenite rock, Ciantia et al. (2015) described (i) outcrops in this region, with significant consequences in a short-term weathering to illustrate the quick reduction terms of hazard for the population and economy. These of geomechanical properties of the rock material from engineering problems are frequently controlled by the dry to wet conditions; (ii) a long-term weathering change of the boundary conditions acting on the rock associated to a relatively slow weathering process mass systems that leads to the variation of the rock usually induced by chemical dissolution processes. To material properties over time, even in a relatively short this purpose, accurate laboratory tests aimed at time (Aydan et al. 2005; Andriani and Walsh 2010; characterizing the most important physical and Ciantia et al. 2015; Hashiba and Fukui 2015; Castellanza mechanical properties of both the intact and the weathered rock material, as well as defining how the transition from dry to saturated conditions; times and weathering degree changes with time and in space, modes of saturation processes are strictly linked to the should be performed in order to define a framework of fabric features of the different facies. The post-peak behaviour of the investigated rocks (Castellanza et al. behaviour of the rock samples was investigated by using 2018).
Lollino, P. (Research Institute for Geo-Hydrological Protection of Italian National Research Council) | Perrotti, M. (Research Institute for Geo-Hydrological Protection of Italian National Research Council) | Fazio, N. L. (Research Institute for Geo-Hydrological Protection of Italian National Research Council) | Parise, M. (University of Bari "Aldo Moro")
ABSTRACT: The presence of man-made underground caves in soft carbonate rocks susceptible to degradation processes due to weathering nowadays induce high risk conditions in the Apulia region (Southern Italy) which is characterised by a huge number of caves spread in the territory. In recent years, several collapses affected some of these cavity systems, involving structures and roads located at the ground surface and, therefore, inducing high risk for human life and properties. In order to comply with this problem at the regional scale, Perrotti et al., 2018, have proposed specific charts aimed at assessing at a preliminary stage the stability conditions of a cave along with a safety margin with respect to the occurrence of failure. The charts have been defined upon the results of a large set of parametric two-dimensional finite-element analyses of ideal cases of underground cavities that account for the typical geometrical features of the caves and the range of mechanical properties of these rocks. The relationships obtained in terms of plots representing the ratio between the strength mobilized at failure and the vertical stress at the cavity roof against the ratio between cave width and roof thickness identify mechanically-based threshold envelopes for stability. In this paper, applications of the stability charts to case studies of man-made underground caves of soft carbonate rocks, either subjected to failure in the past or still stable, are discussed. In the first case the applications proposed show the role of specific structural elements, as pillars and walls, on the general stability of the examined quarry system, while in the second case an indication on the safety factor of the cave with respect to instability has been derived. Therefore, the proposed stability charts have been verified to provide a reliable method to assess in a preliminary way the stability of underground cavities in soft carbonate rocks, so that, for those situations where the safety margin results to be low, more detailed and sophisticated numerical models need to be developed.
Saponieri, Alessandra (Dipartimento di Ingegneria Civile, dell’Ambiente, del Territorio, Edile e di Chimica, Politecnico di Bari) | Valentini, Nico (Dipartimento di Ingegneria Civile, dell’Ambiente, del Territorio, Edile e di Chimica, Politecnico di Bari) | Damiani, Leonardo (Dipartimento di Ingegneria Civile, dell’Ambiente, del Territorio, Edile e di Chimica, Politecnico di Bari) | Amoruso, Vitoantonio (Dipartimento di Ingegneria Civile, dell’Ambiente, del Territorio, Edile e di Chimica, Politecnico di Bari)
Abstract The paper shows a preliminary analysis of the estimation of available wave energy around Apulian coasts. Recently, a wave Atlas of Italian seas has been published, displaying the yearly mean wave power, based on three-hourly wave data set collected by the Italian Wave Network. For the Apulia Region, the buoy belonging to the IWN is placed offshore Monopoli (Bari). In the present study both yearly and monthly mean wave power offshore Apulian coasts are estimated with the analysis of wave data recorded by other two wave buoys placed offshore Tremiti Islands and Taranto. Moreover the comparison between buoys recordings and other two wave data sets provided by the European Centre for Medium-Range Weather Forecasts (ECMWF) and the MeteOcean group of University of Genoa (Italy) is reported.
Abstract The Albanides tectonic setting comprises partly the Apulia Foreland, Orogenic Fold-and-thrust Belts and the Periadriatic Foredeep. Apulia Foreland, named the Sazani zone in Albanides, outcrops along the Karaburuni peninsula and Sazani Island, while at onshore depth its top carbonates is detected in few seismic lines. Meanwhile in the Adriatic Sea and Ionian one offshore, this unit presence is confirmed by three drilled wells and numerous seismic lines, as a thick carbonate sequence of the Triassic to Oligocene age, followed upward by molasses sequences of Miocene to Pleistocene. Albanides Orogeny comprises several Fold-and-Thrust Belts nappes that overthrust onto each other south-westward and entirely onto the Apulia-Sazani Foreland. The overthrust front outcrops obviously at the Llogara pass, whereas its northwest and southeast continuity is completely masked by Periadriatic Foredeep deposits. Periadriatic Foredeep, named the Durresi Depression in Albanides, consists of premolasses, molasses and late molasses deposits of Miocene to Pleistocene that cover transgressively most of the Apulia-Sazani-Paxos Foreland and partly the Ionian-Kruja orogenic nappe. Concerning the hydrocarbon potential, Durresi Depression, Ionian-Kruja nappe and Apulia Foreland are most prolific units, which comprise several types of hydrocarbon accumulation discovered and depicted prospects in the targets of the Cretaceous-Paleogene limestone and the Neogene sandstone. On the other hand, considering geological setting similarity, hydrocarbon exploration results gained in Albanides may be useful references for work in Hellenides, Dinarides and Apennines.
ABSTRACT Underground voids of natural or anthropogenic origin potentially represent a serious hazard to the built-up areas. Urban development and construction of infrastructures often is carried out without taking into account the possibility of encountering subsurface cavities, and the corresponding danger these might pose. In addition, loss of memory of man-made cavities under the historic part of many towns adds further problems. Evaluation of the stability of rock masses in underground setting is not an easy matter, since it requires, in addition to the geological and engineering background, speleological skills and techniques in order to explore and survey the cavities, identify the type of failures occurring therein, and collect the data necessary for the implementation of specific numerical analyses. In this paper we present an approach involving cavers, geologists and engineers to assess the rock mass stability in natural and man-made caves, aimed at determining the control of rock failures in the formation of sinkholes. The methodology is described through the application to a natural karst cave and an anthropogenic cavity in Apulia, SE Italy. In both cases, following a detailed speleological survey which is specifically addressed to define the complete cave topography, the geo-mechanical characterization of the carbonate rock mass was carried out, and the data so obtained were used to evaluate the rock mass stability by means of numerical codes.
The paper deals with the main steps carried out by D'Appolonia, together with the technical designers, to identify, assess and mitigate, when unavoidable, the potential environmental and social impacts due to a natural gas pipe laying in offshore and nearshore waters: namely the Italian section of the IGI -Poseidon project.. The paper describes the identifications of natural and social local elements of sensitivity, which represent a fundamental step in the process of techniques and routing selection and for the choice of proper mitigation measures.
Gomez, Carmen (Stanford Rock Physics Group) | Scotellaro, Cinzia (Stanford Rock Physics Group) | Vanorio, Tiziana (Stanford Rock Physics Group) | Dvorkin, Jack (Stanford Rock Physics Group) | Mavko, Gary (Stanford Rock Physics Group)
Summary This paper describes joint effective-medium modeling of elastic and resistivity laboratory data obtained on a set of outcrop carbonate samples from the Apulia Platform in Italy. The challenge is to model both the elastic-wave velocity and resistivity using a single theoretical approach. The candidate models are (a) the differential effective-medium (DEM) theory and (b) the self-consistent approximation (SC). DEM may accurately describe the elastic properties but fails to describe resistivity, because it explicitly assumes that the pores are inclusions in the mineral matrix and thus lack adequate connectivity. On the other hand, SC treats both the pores and the matrix as inclusions, thus implicitly providing the connectivity needed to match the measured resistivity. At the same time, SC makes it possible to match both the elastic data and the measured resistivity using one set of model parameters. We show that SC, where the rock components are assumed conceptually symmetric, is a robust approach to modeling both velocity and resistivity in our carbonate rock samples, particularly when using needle-like pores, which tend to be stiff but well connected. Introduction Carbonate rocks have a complex pore network, composed of inter- and intra-granular porosity. Here, we model velocity and resistivity laboratory measurements in a consistent manner for a set of carbonate rocks from the Apulia Platform in Italy that includes the Mt. Acuto, Peschici and Gravina formations. The samples cover a wide range of porosity (5 to 52 %), and their lithologic composition is mostly calcite, with some samples having significant dolomite fractions. The resistivity and velocity measurements for this case will be modeled using both theoretical and empirical models. The purpose is to better understand the porous network (porosity and permeability) of these carbonate samples, and how these characteristics reflect on their elastic and electrical properties. Method Our measurements were conducted on 125 core plugs: 31 from the Mt. Acuto formation (MA), 51 from the Peschici formation (FP), and 43 from the Gravina formation (GR and MAT). The core plugs have a diameter of approximately 2.5 cm, and vary in length between 2.4 and 3 cm. Resistivity was measured at 1 kHz at benchtop conditions using the 4-electrode method, with the benchtop set-up that is part of the Core Lab’s Advanced Resistivity System Model 300. The instrumental error for the measured resistivities is 10%. Core plugs were saturated with a calcium carbonate solution, and their water resistivity was monitored for a 48- hour period before the saturated rock resistivity measurements were performed. A calcium carbonate solution was used to ensure that the solution was in chemical equilibrium with the sample, and to minimize dissolution. The resistivity of water was recorded before performing each measurement. At the time of the measurements, the resistivity of the water was 28 ± 5 ohm m. One-hundred percent water saturation was not reached in these samples, particularly in those with low porosity; The average saturation was 90%.
ABSTRACT: Tectonic relationship between the Pre-Apulia Platform and the Albania Thrust Belt (Orogeny), as well as its impacts on hydrocarbon prospects nearby have been geological issues for times. But, recent exploratory works have provided invaluable information on tectonic setting and spatial position of some hydrocarbon prospects. Consequently, it's possible to make out the following main tectonic units and hydrocarbon prospect trends:Pre-Apulia Platform represents a big monocline composed of the Cretaceous-Oligocene carbonates that dips gradually north-eastwards under the Orogeny. Few oil prospects depicted in buried carbonate mounts somewhere are not sealed. So, oil has migrated into sandstone beds of Miocene deposits. Albanids and Hellenides Thrust Belt represents an orogenic assemblage composed of evaporite and carbonate formations of Mesozoic, as well as flysch, flyschoids and premollases of Cenozoic that build up two main tectonic stages and several tectonic zones. Several oilfields and oil prospects depicted in the target of Cretaceous-Eocene limestone are sealed by flysch. Per Adriatic Depression filled up with molasses deposits of the Messinian and the late molasses of the Pliocene that set up the Upper tectonic Stage and lie unconformable on both, the Platform and Orogeny. Sandstone beds of Messinian and Lower Pliocene have been the main target of exploratory works. Consequently, there are few oil and gas fields discovered, as well as few gas prospects depicted so far.
The procedure proposed is basedonthecalculationofthe specificdrinffig energy (SDE) bydrilling parameters and its correlation with strength parameters obtained in the traditional way (for example core drillings and penetrometertests). The procedure may be betterunderstood by considering two case histories. The first regards the foundations of viaducts of the new Bari - Taranto railway (Puglia region, Italy) resting on a pliocenic Calcarenite lying on a Cretaceous limestone, both being jointed and affected by deep karst phenomena; the second concerns the control of vibroflotation treatment oflagoon soils for the embankment ofthe new railway Ancona - Bari (Italy). INTRODUCTION The use ofdrilling parameters for the geotechnical characterization ofthe ground has become possible due to two technological procedures: a) the diffusion of pneumatic and hydraulic drill rigs allowing easy reading and recording of parameters; b) the progress and the diffusion of electronics and informatics, allowing the construction of small recording devices. The resistance to boring is largely utilized in geotechnics when penetrometers are employed, but the non coring drilling technique presents the following advantages: a) it is possible to employ the same machines of constructionworks; b) the rigs needno anchoring orspecial ballasts as the staticpenetrometers; c) theycandrill in all directions as unlike the penetrometers; d) it is possible to drill the hardest rocks and not stop ifa stone is encountered as inthe case ofpenetrometers; e) they can be used to the control ground treatments, generally not easy nor possible with the penetrometers because ofthe ground's density.
Summary Series of samples of calcarenites and tuffs have been subjected to triaxial compression tests with confining pressures up to 100 kg/cm. Due to the peculiar characteristics of these rocks, namely their high porosity and low strength, a complete breakdown of interparticle bonds often occurs within this stress range: the investigated stress range may be thus considered very broad compared to materials’ properties. The behaviour of the rocks shows a definite change with increasing stresses both in hydrostatic and triaxial compression. At low stresses the bonds are still intact and the material shows a typical "rock-like" behaviour (small strains nearly linear stress-strain relationship, brittle failure). At higher stresses, on the contrary the bonds are completely destroyed and the material's behaviour is typically "soil-like". The transition between the two behaviours occurs at stress states that are function of rock strength; for each material a domain of "rock-like" behaviour may be thus defined. 1 — General Soft rocks formations of sedimentary (calcarenites, sandstones) and volcanic origin (tuffs) are frequently found in Italy. In these formations, as a rule, fissures or other structural discontinuities are so widely spaced that they do not affect the behaviour of the rock mass from a Civil Engineering viewpoint; in the mean time, due to the high porosity, the strength of the rock is often rather low and becomes the controlling factor. For these reasons at the "Istituto di Tecnica delle Fondazioni" of Naples University a research on the behaviour of these rocks has been based on laboratory tests on samples. Earlier investigations [1, 2] dealt with the volcanic tuffs of Naples area. Recently some calcarenites have been also studied, so that an exhaustive picture of the stress-strain and strength behaviour of soft rocks has been gained and is here reported. Calcarenites were formed during plio-pleistocene in a littoral environment by chemical cementation of clastic carbonates fragments and fossil debris. They are found over broad areas (up to a thousand of km) in Apulia and Sicily. Résumé On a fait des essais de compression triaxiale, avec une pression latérale montant parfois jusqu’à 100 kg cm sur des types différents de calcarénites et de tufs. Les principales caractéristiques de ces roches, c’est-à-dire la porosité élevée et la basse résistance, ont permis l’essai jusqu’ à la rupture complète des liaisons entre les différentes particules. Le champ de sollicitations examiné peut être donc considéré très vaste par rapport aux caractéristiques des matériaux. Le comportement de la roche varie essentiellement par rapport à l’augmentation de la pression latérale et du déviateur. A des sollicitations peu élevées il n’y a pas de rupture des liaisons et le matériel a un comportement "rocheux" (petites déformations relation tensions-déformations à peu près linéaire, rupture fragile). A des sollicitations très élevées les liaisons sont complètement brisées et le matériel présente un comportement "pulvérulent". Le passage d’un comportement à l’autre a lieu en proportion des différentes valeurs des sollicitations dépendant de la compacité de la roche. Pour chacun des matériaux pris en examen on a donc pu établir un domaine de comportement rocheux. Zusammenfassung Es wurden triaxiale Druckversuche, mit Seitendrücken bis 100 kg/cm, auf verschiedene Arten von "Calcarenite" und Tuff ausgeführt. Die besonderen Eigenschaften dieser Gesteine, und zwar die grosse Porosität und die niedrige Festigkeit, haben erlaubt die Versuche bis zum vollständigen Bruch der Bindungen der verschiedenen Körner zu führen. Das Gebiet der Beanspruchungen, das ausgenützt wurde, kann also als sehr gross angesehen werden, in Bezugh auf die Eigenschaften des untersuchten Gesteines. Die Eigenschaften des Gesteines ändern sich beträchtlich mit zunehmender hydrostatischer Kompressionsspannung und zunehmendem Spannungsdeviator. Bei kleinen Beanspruchungen sind die Bindungen noch ganz erhalten und der untersuchte Stoff zeigt ein "steinartiges" Verhalten (kleine Verformungen, annähernde lineare Beziehung SpannungVerformung, Sprödbruch); bei grossen Beanspruchungen sind die Bindungen gänzlich zerstört und der Stoff zeigt ein ‘ pulverartiges" Benehmen. Der Übergang von einem Verhalten zum anderen geschieht bei Spannungszuständen, die von der Festigkeit des Gesteines abhängen; für jeden untersuchten Stoff wurde deshalb ein Bereich des steinartigen Verhaltens bestimmt.