Evaluation of signal properties when searching for cavities in soil under concrete slabs by radio detection stations of subsurface investigation
- 1 — Mikhailovskaya Artillery Military Academy
- 2 — Saint-Petersburg Mining University
- 3 — Saint-Petersburg Mining University
Abstract
A method of localization of concealed cavities on the basis of studying of the reflected electromagnetic impulses is considered in the paper. An issue of early detecting of concealed cavities in engineering facilities is a critical one due to a significant influence on further serviceability of a structure. Problems of localization of concealed cavities in the soil body under the concrete slabs of hydropower stations were studied; the results of ground radar detecting investigations of the cavities, physical simulation of a cavity as well as a mathematical modeling of a reflected signal are presented. Modern subsurface radar detection provides methods which allow to reliably detect concealed cavities in the soil. However, it is possible only in case of a clear boundary between the adjacent layers that conditions a jump of dielectric permeability. In the result of an abrupt change of dielectric permeability a reflected wave occurred; the existence of subsurface heterogeneity is conditioned by the properties of this wave. Moreover, the greater is the difference between the values of dielectric permeability in the adjacent layers, the larger amplitude the reflected wave will have. If the cavity is at the stage of forming, i.e. it is filled with the soil of reduced density, then there is no clear boundary at the border of the layers which will condition a gradual change of dielectric permeability with depth. In this case an amplitude of a reflected wave will be minimal and a formation signal will be masked out by jamming signals reflected from various heterogeneities. In such case to determine a cavity at the stage of forming seems to be impossible. To determine poor signals an analysis of a phase of a reflected signal may be used; phase alters in compliance with the reflection coefficient change pattern. The article contains information about signals reflected from the heterogeneities and a conclusion regarding a possibility of detecting cavities in the soil on the basis of a method of coherent processing of signals is made.
References
- Андреев Г.А. Радиоволновые системы подповерхностного зондирования / Г.А.Андреев, Л.В.Заенцев, В.В.Яковлев // Зарубежная радиоэлектроника. 1991. № 2. С. 3-22.
- Андрианов В.В. Подповерхностная радиолокация слоисто-неоднородного грунта планеты // Радиотехника и электроника. 1992. Т. 37. № 11. С. 1937-1948.
- Бреховских Л.М. Волны в слоистых средах. М.: Наука, 1973. 343 с.
- Владов М.Л. Введение в георадиолокацию / М.Л.Владов, А.В.Старовойтов. М.: Изд-во МГУ, 2004. 153 с.
- Вопросы подповерхностной радиолокации / Под ред. А.Ю.Гринёва. М.: Радиотехника, 2005. 416 с.
- Изюмов С.В. Теория и методы георадиолокации / С.В.Изюмов, С.В.Дручинин, А.С.Вознесенский. М.: Изд-во «Горная книга». 2008. 196 с.
- Крапивский Е.И. Основы технической диагностики и надежности трубопроводов / Национальный минерально-сырьевой университет «Горный». СПб, 2014. 337 с.
- Петровский А.Д. Радиоволновые методы в подземной геофизике. М.: Недра, 1971. 224 с.
- Подповерхностная радиолокация / М.И.Финкельштейн, В.И.Карпухин, В.А.Кутев, В.Н.Метелкин; Под ред. М.И.Финкельштейна. М.: Радио и связь. 1994. 215 с.
- Теоретические основы радиолокации / А.А.Коростелев, Н.Ф.Клюев, Ю.А.Мельник и др.; Под ред. В.Е.Дулевича. М.: Советское радио. 1978. 608 с.
- Финкельштейн М.И. Радиолокация слоистых земных покровов / М.И.Финкельштейн, В.Л.Мендельсон, В.А. Кутев; Под ред. М.И. Финкельштейна. М.: Советское радио. 1977. 173 с.
- Финкельштейн М.И. Применение радиолокационного подповерхностного зондирования в инженерной геологии / М.И.Финкельштейн, В.А.Кутев, В.П.Золотарев. М.: Недра, 1986. 128 с.
- Якубовский Ю.В. Электроразведка. М.: Недра, 1980. 384 с.
- Ground-penetrating radar reflection rofiling of groundwater and bedrock in an area of discontinuous permafrost / S.A.Arcone, D.E.Lawson, A.J.Delaney, J.C.Strasser, J.D.Strasser // Geophysics. 1998. Vol. 63. № 5. P. 1573-1585.