The authors study the usefulness of geoelectrical resistivity methods for detecting cavities. A theoretical study was conducted of the different conventional measurement arrangements, focused arrangements and special arrangements for geoelectrical investigation between two boreholes. The detectability limits of a cylindrical cavity of given transverse section and depth was calculated for different measurement arrangements by means of apparent resistivity calculations. Furthermore the influence of possible errors is investigated for focused systems. Part 2 considers the apparent resistivity, the disturbing potential due to the cavity, and the normal potential of the measurement arrangement for a homogeneous terrain. In the last part of the article, theoretical results are compared with in-situ measurements. (TRRL)
In this paper we consider the organization of exogenous karst monitoring and providing of geo-ecological safety in complex technical objects. We have substantiated the application of electrical methods for karst-suffusion processes monitoring, for example, Nizhny Novgorod nuclear power plant.
We prove that groups acting geometrically on delta-quasiconvex spaces contain no essential Baumslag-Solitar quotients as subgroups. This implies that they are translation discrete, meaning that the translation numbers of their nontorsion elements are bounded away from zero.