Ricerc@Sapienza

In the mechanized excavation of tunnels with Tunnel Boring Machines, an ever more frequently used technique worldwide is the Earth Pressure Balance (EPB) technology; during the excavation phases this technology requires continuous injection of chemicals under the form of foam to be mixed with the excavated soil.
Since the features of the foam influence significantly the excavation performances and the propagation of induced effects such as settlements in the environment, the studies of the parameters affecting the quality of the foam have great importance for practical purposes.

Tunnel excavations in urban areas are often performed with TBM and Earth Pressure Bal-ance technology which requires the continuous injection of chemicals in the soil condi-tioning process. Several advantages can be achieved by performing laboratory activities prior to starting the excavation in order to predict risks such as clogging in fine grained soils or severe cutter-head wear in coarse soils and to define an optimal range of values for injection parameters.

The most effective, safe and controlled way to perform tunnel excavations is through the use of Tunnel Boring Machines. This technology often requires the injection of chemicals to modify the soil properties, enhancing the control on the pressure applied at the front-face and consequently reducing the risks related to unexpected surface settlements, to excessive abrasion of the excavation tools and to clogging phenomena inside the working chamber.

The paper presents a 3-D numerical strategy developed to accurately simulate the soil-shield and the soil-grout-lining interaction processes associated with the gap closure in mechanized tunneling. The problem is particularly relevant for the structural design of pre-cast lining of very deep tunnels subjected to high stresses.

The paper deals with the numerical modelling of crack formation in segmental tunnel linings. A series of numerical analyses was conducted using the finite difference code FLAC2D. The primary aims of the analyses were to back-analyse the damage pattern observed in a TBM driven hydraulic tunnel excavated in clayey soils and to evaluate the safety level of the excavation assessing the stress and strain state of the lining.

The paper deals with the evaluation of lining forces in TBM-driven tunnels in clayey soils. A 3D numerical model has been developed accounting for the main features of the excavation and construction, such as front pressure, cutterhead overcut, shield conicity, lining installation inside the shield, tail void grouting, grout hardening and injection distance from the shield.

The Water Cooled Lithium Lead (WCLL) is one of the selected breeding blanket (BB) concepts to be investigated in the EUROfusion Breeding Blanket Project (WPBB), and it was also recently chosen as one of the mock-up for ITER Test Blanket Module (TBM) program. The program foresees the test of different BB mock-ups, called Test Blanket Modules, with all the related ancillary systems.

Scavo meccanizzato di gallerie e gestione del terreno di risulta sono un binomio che da tempo può essere considerato inscindibile: entrambi infatti richiedono una accurata progettazione essendo molteplici le problematiche e le professionalità coinvolte, essendo necessario prevedere e valutare rischi per le maestranze coinvolte e per l’ambiente circostante ed essendo particolarmente articolato l’iter di approvazione e di validazione del progetto.

The use of Tunnel Boring Machines (TBM) and particularly the Earth Pressure Balance (EPB) technology is one of the most commonly used way to perform mechanized tunnel excavation. The possibility to perform the excavation with high performance, avoiding risk for workers and reducing the induced subsidence, particularly important in urban area, are the main reason of the growing of this technology.

Earth Pressure Balance (EPB) technology is currently the most widely used technique in mechanized tunnelling with Tunnel Boring Machines (TBMs) and particularly in urban en-vironments, because of several advantages, as the possibility to excavate in different geo-logical conditions and effectively controlling the induced effects on the pre-existing struc-tures. EPB technology requires the continuous injection of chemicals during the advance-ment: this may induce the accumulation of xenobiotic compounds in the excavated debris.