Influence of stope geometry and blasting patterns on recorded overbreak

Abstract

Chemical alteration of the strength of sandstone has been investigated to establish the fundamental knowledge for chemically assisted fracturing. If the rock strength can be chemically lowered, this technology would be useful to raise the fracturing efficiency. The purpose of the present study is to evaluate the effect of chemical solutions on the strength. To evaluate experimentally the effect, Brazilian tests and multi-stage triaxial compression tests have been performed on Gosford sandstone saturated with solutions of dodecyltrimethyl ammonium bromide (DTAB), polyethylene oxide (PEO) and aluminium chloride (AlCl 3 ). The tensile strength varied with the concentration of chemical additives, became the lowest at certain concentrations which are consistent with the zero zeta-potential concentrations. AE activity is the most active in dry specimen, and the least AE activity is found in the specimen saturated with chemical solution. The uniaxial and triaxial strengths did not vary significantly with concentration of the chemical solutions. In case of compression test where failure mode is dominated by shear failure, there is little effect of chemical solutions on the compressive strength.