Abstract
This study used a discrete-element analysis to predict the excavation performance of a 7.73 m-diameter earth pressure balance (EPB) shield tunnel boring machine (TBM). The simulation mainly predicted several excavation performance indicators for the machine, under different operating conditions. The number of particles in the chamber and the chamber pressure varied, as the operating conditions changed during the simulated TBM excavation. The results showed that the compressive force, torque, and driving power acting on the TBM cutterhead varied with its rotation speed, increasing as the cutterhead rotation speed rose. The overall compressive force acting on all of the disc cutters and their impact wear increased linearly as the cutterhead rotation accelerated. The position of a disc cutter on the cutterhead had a particularly strong influence, with higher compressive forces experienced by the cutters closer to the center. In contrast, the gauge disc cutters at the transition zone of the cutterhead showed more wear than those elsewhere. The muck discharge rate and the driving power of the screw conveyor rose with increasing screw conveyor and cutterhead rotation speeds. Finally, this study suggests optimal operation conditions, based on pressure balance and operational management of the TBM.
Highlights
A tunnel boring machine (TBM) can be classified by its use of a shield, method of securing reaction force, face support, cutterhead type, and excavation method [1]
The discrete-element method (DEM) simulation showed that the calculated compressive force on the cutterhead and disc cutter could be considered to be a component of the required thrust force
It was simulated to advance through a ground model of size 1.5 m × 15.6 m × 14.6 m, comprising 400,000 spherical particles of diameter 100 mm, randomly generated and stacked by gravity, after placement of the TBM geometry
Summary
A tunnel boring machine (TBM) can be classified by its use of a shield, method of securing reaction force, face support, cutterhead type, and excavation method [1]. Maynar and Rodríguez [10] conducted the first discrete-element analysis evaluation of an EPB shield TBM They modeled a mixed-face ground composed of six different layers, and simulated its excavation by a 9.4 m-diameter TBM. They assessed the required torque, thrust force, and muck discharge rate. Based on the parameters obtained from Wu and Qu [12], Wu et al [14] created the ground model and a detailed TBM model, based on a real EPB shield TBM (diameter, 6.14 m) used for line 4 of the Beijing metro They evaluated the chamber pressure and cutter force of each disc cutter as well as the required thrust, torque, and muck discharge rate. Tfctliooaioortnnen3v)d)6BewBw0yafaaosossasreresdumd3Rmn6oooPd0nodnMedesttrhlseheu1.elede2nTEdEduchPPneoueBBrdmnTses1dbhhBr2eiiiMdnreecillaodfddftamieiTdfTorfbBevnBeinrMasMnetnaon’’rcstsfotieotttcreaewnoocctnsithhaoadnsnontiiifiastocciilancaommlolansnsulsoppdl—mtaeeiiotctcofeiiniootfifdiuincoccraoasan—ttntciicd~ouofoni2tnotnts0iuseod,,rrmniiihtttscsseim.uoaaaEnt/dddtxsemvv.cRraaahEiPnnnvexMcacac(eetdTais(o(vattaRnbrarnaatlPwiendnoMsas4ntllss)aha.wtstraiiieAomonaennssduasatslcltlhairhmmmteererwoeuodee--wscerreewnocopnavretiycolersRaProMusn.dTthhee TshBiMeldadskviann, ctehewinastesriamctuiolantebdetawte~e2n0thmemsh/mieilnd (sTkainblaen4d).thAes ptharetrieclwesewreansonpoat rctoicnlseisdaerroeudnidn tthheissshtiuedldy.skin, the interaction between the shield skin and the particles was not considered in this study
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