To minimize the social cost and interference with existing facilities, tunnels for cable and electricity have been mostly constructed using trenchless technology in recent years. In this study, a new small-scale excavation method using a multi-hammer tunnelling machine was suggested. To evaluate the optimum operating conditions of the machine, linear percussion testing system to experiment with various conditions was established. Linear percussion tests were conducted considering the air pressure and RPM (i.e., two dominant-field operating conditions). The optimum operating condition of a multi-hammer tunnelling machine for three rock classes was obtained from the test results. Based on the penetration rate data measured from a field test, a prediction chart of the penetration rate was proposed for various rock classes.

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