PROBLEMS OF GEOCOSMOS

Proceedings of the 7th International Conference "Problems of Geocosmos" (St. Petersburg, Russia, 26-30 May 2008)
TEMPORAL VARIATIONS IN GEOPHYSICAL FIELDS AS A
MANIFESTATION OF THE NONLINEAR ROCK PROPERTIES
O.I. Silaeva 1 , A.V. Ponomarev 2 , A.A. Khromov 3 , S.M. Stroganova 4 , T.I. Rudenko 5
1 Institute of Physics of the Earth, Moscow, Russia, e-mail: silaeva@ifz.ru; 2 Institute of
Physics of the Earth, Moscow, Russia, e-mail: avp@ifz.ru; 3 Institute of Physics of the Earth,
Moscow, Russia; 4 Institute of Physics of the Earth, Moscow, Russia, e-mail:
stroganova306@mail.ru; 5 Institute of Physics of the Earth, Moscow, Russia
Abstract. In this study we have conducted research of rock properties changes under explosive
action by means of ultrasonic pule velocity method and apparent resistivity one.
At present a conception on a rock model as an open system having a discrete-block structure was
established. Conception of a rock model as a block medium was put forward by academician Sadovsky.
Actually a block structure of a massif is revealed at geomorphological surveys and distinctly traced on space
photographs. [1, 2]
A research of the medium behavior in time at its destruction (due to explosion or during an
earthquake, rock shock etc.) has a great scientific and practical significance to estimate rock massif stability
in a mine, at carriers’ excavation, trenches, underground cavities, canyons, water reservoirs and creation of
basements of different industrial constructions. In a theoretical paper [3] Rakhmatulin considered
propagation of deformations due to an explosion in a medium where these deformations exceed elasticity
limit. He proved that in this case a specified deformation wave will propagate in it which he called an
unloading wave. This wave is observed by miners during their work in mines with explosions. The
observations entail great technical difficulties. Therefore, there is an urgent need to obtain data on
propagation of slow deformational waves related to deformation process of real blocks of rock massifs
influenced by heavy effects: explosions, rock shocks, earthquakes, reflecting structural reconstruction of a
massif. We selected two geophysical methods to study a rock massif state occurring at its destruction: a
seismic one (in ultrasound frequency band) and an electric one (electrical resistance). These methods allowed
to trace temporal variations of field parameters of seismic and electrical waves related to destruction process
of the massif due to external effects registering a structural reconstruction of the massif at destruction by
underground explosions.
432