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Coupled Systems Mechanics
  Volume 2, Number 1, March 2013, pages 23-51
DOI: http://dx.doi.org/10.12989/csm.2013.2.1.023
 


Analytical model for estimation of digging forces and specific energy of cable shovel
M. Stavropoulou , G. Xiroudakis and G. Exadaktylos

 
Abstract     [Full Text]
    An analytical algorithm for the estimation of the resistance forces exerted on the dipper of a cable shovel and the specific energy consumed in the cutting-loading process is presented. Forces due to payload and to cutting of geomaterials under given initial conditions, cutting trajectory of the bucket, bucket\' s design, and geomaterial properties are analytically computed. The excavation process has been modeled by means of a kinematical shovel model, as well as of dynamic payload and cutting resistance models. For the calculation of the cutting forces, a logsandwich passive failure mechanism of the geomaterial is considered, as has been found by considering that a slip surface propagates like a mixed mode crack. Subsequently, the Upper-Bound theorem of Limit Analysis Theory is applied for the approximate calculation of the maximum reacting forces exerted on the dipper of the cable shovel. This algorithm has been implemented into an Excel TM spreadsheet to facilitate user-friendly, \"transparent\" calculations and built-in data analysis techniques. Its use is demonstrated with a realistic application of a medium-sized shovel. It was found, among others, that the specific energy of cutting exhibits a size effect, such that it decreases as the (-1)-power of the cutting depth for the considered example application.
 
Key Words
    ground-tool interaction;cable shovel; passive earth theory; limit analysis; fracture mechanics; cutting force; specific energy
 
Address
M. Stavropoulou : Department of Dynamic, Tectonic and Applied Geology, Faculty of Geology and Geoenvironment, University of Athens, GR-15784, Greece
G. Xiroudakis and G. Exadaktylos : Mining Engineering Design Laboratory, Department of Mineral Resources Engineering, Technical University of Crete, GR-73100 Chania, Greece
 

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