Seismic measurements on a rock massif surface at short distances

Title:

Seismic measurements on a rock massif surface at short distances

Creator:

Vilhelm, Jan, Rudajev, Vladimír, Roman Živor, and Lokajíček, Tomáš

Identifier:

https://cdk.lib.cas.cz/client/handle/uuid:b1460957-63e9-42da-a85d-9cd9bf83c3ae
uuid:b1460957-63e9-42da-a85d-9cd9bf83c3ae
issn:1214-9705

Subject:

Geologie. Meteorologie. Klimatologie, seizmicita, seismicity, repeatability of measurement, velocity measurement, seismic source, seismic P- and S-waves, 7, and 551

Type:

article, články, model:article, and TEXT

Format:

print, bez média, and svazek

Description:

Various geotechnical tasks require the knowledge of rock properties, e.g., of elastic moduli, fracture systems, inhomogeneities, etc. Seismic measurements usually provide these parameters. To describe the detailed properties of small rock volumes, it is necessary to use high-frequency signals and suitable registration systems. Seismic measurements are carried out directly on rock surfaces. Although the conditions, under which measuremen ts are carried out, seem to be simple and convenient, practical measurements themselves are often complicated. The various measuring systems, including seismic sources and seismic receivers used for different base lengths, are discussed in this paper. It was found that, for the repeatability of measurements, the fixing of the sensors with plaster plays most significant role. Repeatability of hammer blow as seismic source is adversely affected namely by signal amplitude triggering. Pencil lead breaking tests with lead 1 and 6 mm in diameter were found as suitable for testing of the hi gh-frequency measuring systems. Measuring directly on the rock massif surface is different compared to exploration seismic measurements. Due to absence of a low-velocity layer it necessary to use a special choice of mutual orientation of sources and receivers. Polarization analysis may be advantageous to identify the arrival of P and S seismic waves. It was also found that the rock massif behaves as a narrow frequency-b and pass filter. For exciting frequencies of 0.1 and 1 MHz the transmitted signal displayed the same frequency of 25 kHz at a distance of 1.1 m., Jan Vilhelm, Vladimír Rudajev, Roman Živor and Tomáš Lokajíček., and Obsahuje bibliografické odkazy

Language:

English

Rights:

http://creativecommons.org/licenses/by-nc-sa/4.0/
policy:public

Source:

Acta geodynamica et geomaterialia : | 2012 Volume:9 | Number:2 (166)

Harvested from:

CDK

Metadata only:

false