An evaluation on rippability of geological units by seismic P- and S-wave velocities


Creative Commons License

KARSLI H. , BABACAN A. E. , ŞENKAYA M. , GELİŞLİ K.

PAMUKKALE UNIVERSITY JOURNAL OF ENGINEERING SCIENCES-PAMUKKALE UNIVERSITESI MUHENDISLIK BILIMLERI DERGISI, vol.27, no.3, pp.411-420, 2021 (Journal Indexed in ESCI) identifier

  • Publication Type: Article / Article
  • Volume: 27 Issue: 3
  • Publication Date: 2021
  • Doi Number: 10.5505/pajes.2020.35920
  • Title of Journal : PAMUKKALE UNIVERSITY JOURNAL OF ENGINEERING SCIENCES-PAMUKKALE UNIVERSITESI MUHENDISLIK BILIMLERI DERGISI
  • Page Numbers: pp.411-420
  • Keywords: Seismic P- and S-wave velocities, Rippability, Trabzon Province, POROSITY

Abstract

Seismic P- and S- wave velocities are directly dependent on the physical properties of the geological units (soil and rock) in which they propagate, the degree of decomposition and fracture-crack, depth and porosity, and are widely used in estimating the rippability in excavation works. P- and S-wave velocities of geological units can be determined by seismic refraction and multichannel surface wave analysis (MASW) methods, respectively, in the field. The rippability classes can be estimated quickly and reliably in relation to the distribution of the seismic velocities in 1 and 2 dimensions (1D and 2D) and geotechnical characteristics of geological units. In this study, data from many in situ seismic measurements performed in four different areas in vicinity of center of Trabzon province were re-evaluated using P- and S-wave velocity classification tables prepared according to international standards (Caterpillar and NEHRP) for the rippability of geological units in the measurement areas and a primary seismic velocity-rippability-geotechnical classification table was prepared by including S-wave velocity. Therefore, the type (soil, rock) and mechanical property (firm, solid, hard, etc.) of the geological units are defined according to the S-wave velocity and the degree of rippability according to the P-wave velocity. Accordingly, in general, the geological units in the study areas are classified as very easy-to-easy, less firm soil (Vp <900 m/s, Vs <300 m/s), moderately rippabile solid-firm soil (Vp approximate to 900-1500 m/s, Vs approximate to 400-600 m/s), hard to rippabile very firm-solid or weathered rock (Vp approximate to 1500-2100 m/s, Vs approximate to 600-800 m/s), very hard-to-extremely hard to rippabile solid rock (Vp approximate to 2100-2400 m/s, Vs approximate to 800-1100 m/s) and non-rippabile hard rock (Vp>2400 m/s, Vs>1100 m/s). In addition, it has been shown that the approximate limits ofgeological units on 2D P-wave velocity-depth sections. Consequently, the evaluation of P- and S-wave velocities together has provided the information about the type (soil or rock), mechanical and physical properties of the geological units besides the rippability, thus will ensure minimizing the rippability estimation errors and to the guiding of excavation works.