1,721,008 research outputs found
Soil Conditioning and Ground Monitoring for Shield Tunnelling
No full textSoil conditioning consists of mixing and remolding the natural material during the mechanical excavation of tunnels, generally at low depth, with additives, in order to obtain suitable properties of plasticity and consistency for the excavated material, so becoming able to apply a counterpressure against natural earth pressure and groundwater flow towards the excavation chamber. The assessment and the control of the soil parameters and of machine performance are fundamental for a regular and safe excavation, also with regards to surface stability. This paper mainly focus on testing approach aimed to the proper soil conditioning with EPB shields, whose results have been validated at real scale. The influence of the water content and the amount of conditioning foam has been studied by the Authors. A proper definition of conditioning parameters can allow to extend the application field of Earth Pressure Balance (EPB) tunnel machines to various grain soil distribution, even in weak rock formations (e.g. siltstone or flysch). Importance of conditioning is reflected also on the possibility of a proper spoil disposal or better for its reuse
Properties of non-conventional waste and geomaterials for reuse in excavation sites
Full text linkThis is the author accepted manuscript.Reuse and recycling of waste material from excavation and mining/quarrying activities is a global issue that
received significant attention in the last decades. The links among local geology, excavation methods, spoil
treatment and strategies for recycle have been identified as unavoidable in terms of early physical, chemical and
mechanical characterisation of spoils. The emergence of a range of industrial waste streams and the
environmental, economic and technical considerations arising from their recycle and reuse still need a
comprehensive technical and validated procedure for acceptance.
This paper describes the screening tests and treatment options for material recycling in the framework of an
original spoil classification system, also for specific applications, such as drainage layers, covering of dumps,
rehabilitation of abandoned sites. The experience learnt by the Authors from the development of suitable
methodologies for characterisation and management of spoil waste can be extended to other waste such as glass
waste, gypsum, rockwool, glasswool, granulates, chipping particles, polymeric cuttings which show similarities
with soils and geomaterials in terms of ‘bulk behaviour
Tunnel spoil classification and applicability of lime addition in weak formations for muck reuse
No full textTunnel construction planning requires careful consideration of the spoil management part, as this involves environmental, economic and legal requirements. In this paper a methodological approach that considers the interaction between technical and geological factors in determining the features of the resulting muck is proposed. This gives indications about the required treatments as well as laboratory and field characterisation tests to be performed to assess muck recovery alternatives. While this reuse is an opportunity for excavations in good quality homogeneous grounds (e.g. granitic mass), it is critical for complex formation. This approach has been validated, at present, for three different geo-materials resulting from a tunnel excavation carried out with a large diameter Earth Pressure Balance Shield (EPB) through a complex geological succession. Physical parameters and technological features of the three materials have been assessed, according to their valorisation potential, for defining re-utilisation patterns. The methodology proved to be effective and the laboratory tests carried out on the three materials allowed the suitability and treatment effectiveness for each muck recovery strategy to be defined
Damage and contour quality in rock excavations for quarrying and tunnelling: assessment for properties and solutions for stability
Full text linkThis is the author accepted manuscript.Excavations in rock masses determine the creation of temporary or final exposed surfaces. Features of these surfaces are depending on both geostructural pattern of the rock mass and adopted excavation method: among the others, roughness, quality of the contour and induced damage inside the rock left in place. These aspects are important as they are requirements expected during the excavation and construction procedures, such those involving dam sidewalls, quarry benches, tunnel profile, slope scaling. This methodological paper describes a list of the possible cases, with a particular emphasis on quarrying and tunneling. By following current modes for profile surveying, the damages are reported, in order to obtain suitable indices for induced damage. Finally the proper techniques for excavation are commented on the basis of real case histories of tunnels and quarries in order to reach the primary objectives of damage reduction and stability/productivity goals
Tunnelling muck classification:definition and application
No full textExcavated material management represents today a key issue due to environmental constraints and to the claim for possible reuse. Therefore, the knowledge of muck characteristics has become a topic of high interest. The muck can show different properties and behaviour, mainly due to the local geology, to the excavation mode and to the possible treatment. On the basis of the properties and of the possible local or remote recycling, the spoil can be processed in a treatment plant or sent to disposal. As the ground types can change along the tunnel, it is important to assess its variability in order to adapt the plant capability for producing a suitable by-product. For these reasons, a procedure for classifying the spoil from tunnelling is proposed (TMC). It represents a simple and practical tool for correlating ground type, possible muck destination and treatment type. Testing plan of the materials for the possible different muck destination should be compiled and conditions for safe waste disposal should be analysed as well
Problems concerning cutting tool performance during TBM work: modelisation and testing of the rock under the action of the tool
Full text linkIn rock excavation engineering, cutting performance prediction plays an important role in machine and cutting tool design. In the past, experimental and theoretical studies on the interaction between rock and TBM tools were conducted for the explanation of the intimate mechanism of rock failure and to obtain knowledge that was able to improve the performances of the TBMs. Nevertheless,, despite several decades of academic rock mechanics and practical rock engineering, there is still a lack of some fundamental knowledge on rock-tool interaction. The objective of this paper is to evaluate a model that predicts the distributed displacement and stresses under a TBM disk, taking into account, in the failure mode, the constitutive law of the rock, the presence of the tunnel head, the amount of the natural stress due to the high overburden, and the forces caused by the TBM disk on the tunnel head. Some laboratory tests were also planned to validate the theoretical results
Validation of numerical D.E.M. modelling of geogrid reinforced embankments for rockfall protection
Full text linkThis is the final version. Available on open access from Pàtron Editore via the DOI in this recordThe adoption of reinforced embankments for rockfall and landslide protection purposes is an effective
intervention for the reduction of risk and damages to civil facilities. These earth structures are manufactured with
layers of compacted soil alternated with geosynthetics (e.g. geogrids and geotextiles) that are anchored to the
outer quarterdeck frame or wrapped around it. This paper discusses the results obtained with a numerical
simulation of the reinforced embankment carried out by means of a distinct element commercial (D.E.M.) code
as particle code (P.F.C.). Several types of rock impacts on an embankment were simulated, varying block
speeds, energies and geometrical impact conditions. Data from practical experiences of the authors and data from
full-scale impact tests gathered from relevant literature, were used for the validation of the model. The main
result of the work is the development of design operative suggestions that can support the selection of the design
parameters of an embankment for rockfall protection purposes: its preliminary size based on impact energy level
and induced damages can be outlined. The results of this provide guidance to designers and relevant stakeholders
in the evaluation of risk scenarios arising from potential rock falls on infrastructures
Defining the borders between Sleep-Related Eating Disorder and Night Eating Syndrome
No full textAbstract not availablePiergiuseppe Vinai, Raffaele Ferri, Luigi Ferini-Strambi, Silvia Cardetti, Matteo Anelli, Paola Vallauri, Noemi Ferrato, Marco Zucconi, Gabriella Carpegna, Mauro Mancon
New data on psychological traits and sleep profiles of patients affected by nocturnal eating
No full textAbstract not availablePiergiuseppe Vinai, Raffaele Ferri, Matteo Anelli, Luigi Ferini-Strambi, Marco Zucconi, Alessandro Oldani, Mauro Mancon
Large Scale Trials of Waste Mine Burden Backfilling in Pit Lakes: Impact on Sulphate Content and Suspended Solids in Water
Full text linkThe paper describes the results obtained from a large-scale trial designed to assess the impact of the backfilling of waste mine burden in an exhausted pit on the quality of lake water. The trial aimed at understanding the interaction between groundwater and clay and silty sand soils composing the overburden material. The two main environmental concerns related to the turbidity of the water and the concentration of sulphate ions. Tests were designed to (I) assess the interaction between soil and water; (II) measure the turbidity of water, related to the amount of solid particles in suspension; (III) observe the sedimentation of fine particles; (IV) measure the concentration of sulphate ions during backfilling and water pumping operations; and (V) validate an analytical model for the prediction of sulphate quantity in water. The main results indicated that the basin was capable to retain particles with sizes in the order of diameters that were nearly 10 microns. The water pumping was responsible for a relevant motion of fine particles (diameter less than 2 μm); this effect impacted on the turbidity level observed at the outflow in a relevant way. On the other hand, the test indicated that the estimation of the release of sulphate ions in the water was heavily affected by a proper assumption of the average background values of the concentration of sulphate ions in the water before the dumping activity
- …
