TY - THES

T1 - Theoretical investigations on the influence of artificially induced joints on the performance of mechanical rock excavation by roadheaders

AU - Bock, Stefan

N1 - embargoed until null

PY - 2017

Y1 - 2017

N2 - The influence of the specific energy to the cutting performance was investigated and different hybrid cutting performance perdition models were established. Those models vary in different cutting depths and different preconditioning depths of the tunnel face. The most effective forecast model of Mr. Comakli was investigated in more detail. These multi regression models sets the uniaxial compressive strength, Brazilian tensile strength, Schmidt hammer value, ultrasonic test, dry density and porosity into relation. The original equation creates a correlation value of 0.98. As the best precondition technique the microwave fragmentation was chosen, because the horizontal and radial cracks create an easier situation for extraction of the tunnel face with a roadheader cutting head than e.g vertical laser drilled holes. Lower the rock mass rating by a factor of 20% will lead to an improvement of the performance, expressed by the net cutting rate of 22%. The preconditioning with laser drilled holes (vertical and inclined) was interpreted as not sufficient for mining operations, because the tunnel face will get too hot and the thermal wear of the wolframite pick will move out of the economic situation. The most effective cutting situation could be a microwave preconditioned face and a water jet assisted cutting process. As best the precondition will be, as higher the cutting performance will be in the end.

AB - The influence of the specific energy to the cutting performance was investigated and different hybrid cutting performance perdition models were established. Those models vary in different cutting depths and different preconditioning depths of the tunnel face. The most effective forecast model of Mr. Comakli was investigated in more detail. These multi regression models sets the uniaxial compressive strength, Brazilian tensile strength, Schmidt hammer value, ultrasonic test, dry density and porosity into relation. The original equation creates a correlation value of 0.98. As the best precondition technique the microwave fragmentation was chosen, because the horizontal and radial cracks create an easier situation for extraction of the tunnel face with a roadheader cutting head than e.g vertical laser drilled holes. Lower the rock mass rating by a factor of 20% will lead to an improvement of the performance, expressed by the net cutting rate of 22%. The preconditioning with laser drilled holes (vertical and inclined) was interpreted as not sufficient for mining operations, because the tunnel face will get too hot and the thermal wear of the wolframite pick will move out of the economic situation. The most effective cutting situation could be a microwave preconditioned face and a water jet assisted cutting process. As best the precondition will be, as higher the cutting performance will be in the end.

KW - artificially induced joints

KW - mechanical rock excavation

KW - roadheaders

KW - induzierten Klüfte

KW - Vortriebsleistung von mechanischen Vortriebsmaschinen

KW - Roadheader

M3 - Master's Thesis

ER -