This paper presents a linear scaled distance methodology to estimate peak particle velocity (PPV) originated from blasting rounds, developed specifically for tunneling and drifting operations. It considers input parameters that are characteristic of different rock mass qualities, such as propagation velocity and resonance frequency, and explosive characteristics such as velocity of detonation (VOD) and the geometry of the blasting round. The final PPV value of any particular blasthole of the round is determined through the linear superposition of multiple waveforms, generated for a number of small incremental charges, each scaled by the distance from the explosive source to the point of interest. In addition, every waveform is shifted in time from the difference of their respective arrival times as they arrive to the point of interest. As a result of these considerations, the proposed methodology can yield a much more precise estimation of the PPV levels, which is a fundamental parameter to assess the damage potential the rock is being subjected to.
In prior research the existence of the strong relation between peak particle velocity, as a result of blasting, and damage to civil structures and mining excavations has been well established [1, 2, 3 and 4]. In essence, the higher the PPV levels, the greater has been the observed damage to a structure or excavation. Estimating PPV levels occurring at any given location (with respect to the explosive charge) as accurately as possible thus becomes critical toward making better, more reliable predictions of the potential for damage to existing structures and excavations.
The proposed methodology or the model from here on, is a modification to the original Hustrulid-Lu method [5] used for the near-field PPV prediction, where the arrival time delay, among small incremental charges pertaining to the a single blasthole, have been incorporated.