عنوان مقاله [English]
Estimation of cutting forces acting on a disc cutter while cutting rock has been used for cutter head design and performance prediction of tunnel boring machines (TBMs). On the other hand, cutting forces is resulted from pressure in contact zone between disc cutter and rock. In this study, numerical modeling of rock cutting procedure with disc cutter by applying commercial finite element code ABAQUS is performed and in order to validate this model, contact zone pressure between disc and rock was compared by Rostami(1997) ‘s semi-empirical model. Modeling Shows 14 error percentage that confirms good relation between two models. The other result of this modeling is study the effective geometrical parameters of disc in pressure distribution of contact zone area in linear rock cutting procedure.
In this Study, linear rock cutting procedure of a single disc cutter was modeled by Commercial finite element code ABAQUS/CAE. Numerical models of rock and disc with perfect match by laboratory testing of linear rock cutting test by Rostami(1997) was built and finally validated. Pressure distribution of cutting zone with considering of non-loading zones was studied and was compared with semi-empirical model of Rostami(1997). With lower than 14% of error percentage comparing laboratory result, This models shows a perfect match. Also, geometrical parameters of disc cutter was studied to find the effects on pressure distribution zone of contact area. With a longitude and a latitude cross sections of rock model in cutting path, it was concluded that with increasing edge and angle of disc tip, micro cracks was formed in rock. Although the disc diameter causes increasing weight of disc, resulted pressure distribution has less changes.
Rock cutting procedures is an indentation of a cutter into rock that formed a pressure bubble immediate beneath cutter in rock and finally a soft powder is formed around the cutter. This bubble develop a crack pattern to rock material. In 1993, Rostami & Ozedmir believe that this bubble has a hydrostatic pressure forms that has linear behavior but in 1997 by calibration of disc and do more rock cutting tests, found out the other form of pressure bubble and non-loading zones exist in rear and forward of disc cutter in cutting procedure.
Methodology and Approaches
In order to modeling linear rock cutting procedures, Commercial finite element code ABAQUS/CAE was employed and for validating that, laboratory linear rock cutting test by Rostami (1997) was considered. Rock and disc cutter models was built in ABAQUS GUI module and to simulate rock behavior of rock model, Strength criterion with linear equation of state was implemented to material model. Boundary Condition for disc cutter was similar to TBM’s working status with linear velocity of 2 meter per seconds and angular velocity of 9.3 radians per seconds.
Results and Conclusions
The results from Numerical modeling of rock cutting that validated by laboratory test of Rostami (1997) shows prefect match with semi-empirical model. Even though this model can be employed in other applications of TBM designs, more study is needed to find out deeper issues of rock cutting procedures.