The present invention relates to a method to excavate a huge tunnel with a large cross section through radial expansion blasting of a pre-large hole using a tunnel boring machine (TBM), capable of reducing a construction period. According to the present invention, the method comprises: a pre-large hole boring step of pre-boring a part of a cross section of a tunnel in the longitudinal direction of the tunnel to be excavated; a radial charge hole boring step of boring a plurality of charge holes in a radial shape on the inner surface of a pre-large hole; a time delay blasting step of sequentially blasting each explosive with time delays; a muck removing step of removing muck of a space formed by time delay blasting; a support material installation step of installing a support member to sustain and keep an excavated surface formed through the time delay blasting; and a bench removing step of removing a bench up to the bottom surface of the tunnel. The radial charge hole boring step to the bench removing step or the pre-large hole boring step to the bench removing step are repeatedly performed.;COPYRIGHT KIPO 2019
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