The Reliability of a Tunnel Boring Machine

ABSTRACT Greater levels of complexity in tunnelling with Tunnel Boring Machine (TBM) allow higher chances of fail-ures that may increase the potential hazardous risks. This paper presents the results of a study on TBM reliability using risk analysis. Machinery Failure Mode and Effect analysis was applied to analyze the risks of a TBM using QS9000 and SAE.J1739 recommendations. For this purpose, 48 failure modes were pos-tulated for the TBM main systems and all subsystems. Afterwards, the effects of every failure were listed. Safeguards or controls that might prevent or mitigate the effects of each failure were also listed. In the final step, essential remedial actions to prevent or mitigate the failure were recommended. Risk Matrix was developed for each possible failure to be used for risk ranking. For this, the Risk Priority Number (RPN) was estimated for each failure mode for pro and post application of control measures to identify the most critical failures. The results revealed that 7 failure modes had risk priority numbers higher than 80 therefore, they were categorized unacceptable. Cutter head stop due to bad rock condition with RPN=240 was the significant critical failure. The results also showed that 3 failure modes in TBM required modifica-tion due to high Severity rate. The findings from this study were applied to a long tunnel under construc-tion and significantly reduced the accidents during the next two years tunnelling period. It can be con-cluded that MFMEA is a superb tool for TBM reliability evaluation and promotion. Keywords: Risk, Tunnelling, Analysis, Hazard, Tunnel Boring Machin

Proposal for a lunar tunnel-boring machine

A need exists for obtaining a safe and habitable lunar base that is free from the hazards of radiation, temperature gradient, and micrometeorites. A device for excavating lunar material and simultaneously generating living space in the subselenian environment was studied at the conceptual level. Preliminary examinations indicate that a device using a mechanical head to shear its way through the lunar material while creating a rigid ceramic-like lining meets design constraints using existing technology. The Lunar Tunneler is totally automated and guided by a laser communication system. There exists the potential for the excavated lunar material to be used in conjunction with a surface mining process for the purpose of the extraction of oxygen and other elements. Experiments into lunar material excavation and further research into the concept of a mechanical Lunar Tunneler are suggested

The behaviour of a two-component backfilling grout used in a Tunnel-Boring Machine

The instantaneous filling of the annulus that is created behind the segment lining at the end of the tail during the TBM advance is an operation of paramount importance. Its main goal is to minimize the surface settlements due to any over-excavation generated by the passage of the TBM. To correctly achieve the goals, a simultaneous backfilling system and the injected material should satisfy the technical, operational and performance characteristics. A two-component system injection for the back-filling is progressively substituting the use of traditional mortars. In this paper different systems of back-filling grout and in particular the two-component system are analyzed and the results of laboratory tests are presented and discusse

TBM pressure models: observations, theory and practice

Mechanized tunnelling in soft ground has evolved significantly over the last 20 years. However, the interaction between the tunnel boring machine (TBM) and the ground is often understood through idealized concepts, focused mostly on the machine actions in detriment of the reactions from the ground. These concepts cannot be used to explain several mechanisms that have been observed during the construction of mechanized tunnels. Therefore, this paper presents the path from field observations to the theoretical developments to model the TBM-ground interaction more realistically. Some ideas on how these developments can be applied into practice are presented. Finally, a discussion is proposed about how an effective collaboration between academia and industry can alleviate the current concentration of knowledge in the state of practice

Studying the Effect of Tunnel Depth Variation on the Specific Energy of TBM, Case Study: Karaj–Tehran (Iran) Water Conveyance Tunnel

The tunnel-boring machine (TBM) is a common piece of equipment used in tunneling projects. For planning a mechanical excavation project, prediction of TBM performance and the specification of design elements such as required forces are critical. The specific energy of excavation (SE), i.e. drilling energy consumption per unit volume of rock mass, is a crucial parameter for performance prediction of a TBM. In this study, the effect of variation of tunnel depth on SE by considering the post-failure behavior of rock mass was investigated. Several new relations between SE and tunnel depth are proposed according to the statistical analysis obtained from Karaj–Tehran Water Conveyance Tunnel real data. The results showed that there is a direct relation between both parameters and .A polynomial equations are proposed as the best expression of the correlation between these parameters

Exploration of a High Luminosity 100 TeV Proton Antiproton Collider

New physics is being explored with the Large Hadron Collider at CERN and with Intensity Frontier programs at Fermilab and KEK. The energy scale for new physics is known to be in the multi-TeV range, signaling the need for a future collider which well surpasses this energy scale. We explore a 10$^{\,34}$ cm$^{-2}$ s$^{-1}$ luminosity, 100 TeV $p\bar{p}$ collider with 7$\times$ the energy of the LHC but only 2$\times$ as much NbTi superconductor, motivating the choice of 4.5 T single bore dipoles. The cross section for many high mass states is 10 times higher in $p\bar{p}$ than $pp$ collisions. Antiquarks for production can come directly from an antiproton rather than indirectly from gluon splitting. The higher cross sections reduce the synchrotron radiation in superconducting magnets and the number of events per beam crossing, because lower beam currents can produce the same rare event rates. Events are more centrally produced, allowing a more compact detector with less space between quadrupole triplets and a smaller $\beta^{*}$ for higher luminosity. A Fermilab-like $\bar p$ source would disperse the beam into 12 momentum channels to capture more antiprotons. Because stochastic cooling time scales as the number of particles, 12 cooling ring sets would be used. Each set would include phase rotation to lower momentum spreads, equalize all momentum channels, and stochastically cool. One electron cooling ring would follow the stochastic cooling rings. Finally antiprotons would be recycled during runs without leaving the collider ring by joining them to new bunches with synchrotron damping.Comment: 11 pages, 20 figures, SESAPS 2015 Conference. Reference correcte

Recurrent neural networks and proper orthogonal decomposition with interval data for real-time predictions of mechanised tunnelling processes

A surrogate modelling strategy for predictions of interval settlement fields in real time during machine driven construction of tunnels, accounting for uncertain geotechnical parameters in terms of intervals, is presented in the paper. Artificial Neural Network and Proper Orthogonal Decomposition approaches are combined to approximate and predict tunnelling induced time variant surface settlement fields computed by a process-oriented finite element simulation model. The surrogate models are generated, trained and tested in the design (offline) stage of a tunnel project based on finite element analyses to compute the surface settlements for selected scenarios of the tunnelling process steering parameters taking uncertain geotechnical parameters by means of possible ranges (intervals) into account. The resulting mappings of time constant geotechnical interval parameters and time variant deterministic steering parameters onto the time variant interval settlement field are solved offline by optimisation and online by interval analyses approaches using the midpoint-radius representation of interval data. During the tunnel construction, the surrogate model is designed to be used in real-time to predict interval fields of the surface settlements in each stage of the advancement of the tunnel boring machine for selected realisations of the steering parameters to support the steering decisions of the machine driver

Procedure esecutive in presenza di convogli eccezionali su ponti stradali privi di documenti progettuali

La presente nota riguarda le procedure adottate per verificare l'ammissibilità del transito di convogli eccezionali su quattro viadotti esistenti lungo la S.S. 640 Agrigento-Caltanissetta per il trasporto di componenti della Tunnel Boring Machine (TBM) per la realizzazione della nuova Galleria Caltanissetta. Si descrivono le ispezioni ed i rilievi effettuati al fine di determinare le caratteristiche geometriche delle opere d'arte, le indagini sui materiali al fine di caratterizzarne la resistenza. Inoltre, facendo riferimento alla normativa in vigore all'epoca di progettazione, si sono disposte prove di carico preliminari tali da indurre sollecitazioni prossime a quelle indotte dal transito dei convogli eccezionali. Sulla base dei risultati delle suddette prove è stato autorizzato da parte dell'ANAS il transito dei convogli, rilevando gli spostamenti dell'impalcato. Il convoglio speciale è costituito da 20 assi, avente un peso complessivo non superiore a 3670 kN.This paper concerns the procedures used to verify the allowability of the transit of track live loads on four existing bridges along the road S.S. 640 Agrigento-Caltanissetta, in order to move some parts of the Tunnel Boring Machine (TBM), used for the tunnel construction of the Galleria Caltanissetta. We describe the inspections and surveys performed, in order to obtain the geometric configurations, the tests on the concrete and on the reinforcing steel. Furthermore, with reference to design code at the time of construction, we scheduled the load tests by using tracks that induced stresses similar to TBM components loads. On the bases of the tests results the owner (ANAS) authorized the transit on the four bridges of convoys consisting of 20 axes, having a total weight not more than 3670 kN

Slurry infiltration tests for slurry shield tunnelling in saturated sand

Tunnelling in saturated sand will cause excess pore pressures in the sand. This was the case during the construction of all tunnels in the Netherlands. This excess pore pressure influences the stability of the tunnel face. Therefore the magnitude of the excess pore pressure is of importance. Furthermore, it requires more information on the penetration process of the bentonite slurry as it will occur at the front of the tunnel face. This paper deals with preliminary infiltration tests to investigate some aspects of the infiltration. Results will be compared with theory