Dependence Models of Borehole Expansion on Explosive Charge in Spherical Cavity Blasting

Abstract

In geotechnical practice, it is often necessary to improve the properties of soil and rock in which different structures are built. For this purpose, spherical cavity blasting can be applied to expand the borehole. Such expansion may incorporate various constructive elements such as anchors and thus stabilize the slope. The paper presents the method for determining the increased volume, expansion, and deepening of the borehole as a result of spherical cavity blasting. In addition, mathematical models describing the dependency of the borehole expansion on the amount of explosive charge are presented. The models are mutually compared with the Akaike information criterion.

Comparative Analysis of Basic and Extended Power Models of Boreholes Expansion Dependence on Explosive Charge in Blasting in Clay Soil

“…Other than performed research from 2014 to 2016 [15], and researche in Težak, D. 2018 [6] and Težak, D. et al 2019 [1], there are a couple of similar methods found in literature.…”

“…The area of interest was blasted in soft rock in order to create spherical volume cavities using different types and masses of explosive. Collection of all the field data and the innovative approach in data processing were published in Težak D. et al, 2019 [1].…”

“…Spherical cavity blasting is one-time or multiple time blasting of small explosive charges at the bottom of the borehole with the purpose of expansion [1,2]. Detonation of the explosive charge at the bottom of the borehole results in a high value of pressure of detonation products [3,4].…”

“…Original data source, for the volume of spherical cavity (V rc ), horizontal (L re ), and vertical (D re ) borehole increase, were obtained in field research from 2014 to 2016 [6,15]. Težak D. et al, 2019 [1] introduced the initial values of spherical cavity volume, horizontal, and vertical borehole increase. The inclusion of these values in the database resulted in the reduction of the error of estimation of the dependence of the boreholes expansion on the explosive charge during spherical cavity blasting.…”

“…In all six cases, combinations of one of three efficiency indicators (V rc , L re and D re ) and type of explosive (Pakaex and Permonex V19), power model turned out to be the most efficient. Power model gives smallest estimation error values shown as the sum of square residuals (SS), largest values of determination coefficient (R 2 ) and smallest loss of information shown by Akaike's Information Criteria (AIC and AIC c ) [1].…”