An Estimation Method of In-situ Rock Masses by Characteristic of Electric Resistivity for Jointed Rock Mass Model
Makoto NAKAMURA and Harushige KUSUMI
Abstract:Before the underground structures such as tunnels are constructed, electrical prospecting is often applied, because of its sensitivity for the water included in the rock mass. However, the relationship between resistivity and the physical property of the rock mass has not quantitatively been clarified. Especially, in the jointed rock mass, it is important to grasp the influence of the joint on the resistivity. In this paper, two kinds of jointed rock mass model are used. One is the discontinuity model, which is made to change the open width of discontinuity by inserting various number of filter papers. The other is the porous model, in which micro opening cracks are generated inside the rock by heating with the electricity muffle furnace. Using these models, the characteristics of resistivity for the jointed rock mass are examined by comparing with the field data obtained by electrical prospecting. As the result, it is shown the possibility to evaluate the porosity of in-situ rock mass from the relationship between porosity and resistivity of the porous model. Key Words:Jointed rock mass, Intact rock specimen, Heating, Discontinuity, Characteristics of resistivity