We investigate the relationships between the in situ P-wave velocity (Vp) of rock masses, measured by borehole acoustic logging, and their Geological Strength Index (GSI), to support a reliable assessment of equivalent continuum rock mass properties at depth. We quantified both Vp and GSI in three deep boreholes drilled in a crystalline core complex of the central Italian Alps. The boreholes were driven up to 400 m in depth and provided high-quality drill cores in gneiss, schist and metasedimentary rocks with variable lithology. Geological and geomechanical logging was carried out for over 800 m of cores, and acoustic logging was performed for more than 600 m of borehole length. High-resolution core logging in terms of GSI was obtained using an original quantitative approach. Candidate empirical correlation functions linking Vp and GSI were tested by a two-step statistical analysis of the experimental dataset, including outlier removal and nonlinear regression analysis. We propose a sigmoid Vp–GSI equation valid over a depth range between 100 and 400 m. This accounts for extremely variable lithological, weathering and rock mass damage conditions, complementing existing shallow-depth approaches and showing potential for practical applications in different engineering settings.

Agliardi, F., Sapigni, M., Crosta, G. (2016). Rock Mass Characterization by High-Resolution Sonic and GSI Borehole Logging. ROCK MECHANICS AND ROCK ENGINEERING, 49(11), 4303-4318 [10.1007/s00603-016-1025-x].

Rock Mass Characterization by High-Resolution Sonic and GSI Borehole Logging

AGLIARDI, FEDERICO
;
CROSTA, GIOVANNI
Ultimo
2016

Abstract

We investigate the relationships between the in situ P-wave velocity (Vp) of rock masses, measured by borehole acoustic logging, and their Geological Strength Index (GSI), to support a reliable assessment of equivalent continuum rock mass properties at depth. We quantified both Vp and GSI in three deep boreholes drilled in a crystalline core complex of the central Italian Alps. The boreholes were driven up to 400 m in depth and provided high-quality drill cores in gneiss, schist and metasedimentary rocks with variable lithology. Geological and geomechanical logging was carried out for over 800 m of cores, and acoustic logging was performed for more than 600 m of borehole length. High-resolution core logging in terms of GSI was obtained using an original quantitative approach. Candidate empirical correlation functions linking Vp and GSI were tested by a two-step statistical analysis of the experimental dataset, including outlier removal and nonlinear regression analysis. We propose a sigmoid Vp–GSI equation valid over a depth range between 100 and 400 m. This accounts for extremely variable lithological, weathering and rock mass damage conditions, complementing existing shallow-depth approaches and showing potential for practical applications in different engineering settings.
Articolo in rivista - Articolo scientifico
Acoustic logging; Borehole geophysics; Empirical correlation; Geological Strength Index; P-wave velocity; Rock mass characterization;
Acoustic logging; Borehole geophysics; Empirical correlation; Geological Strength Index; P-wave velocity; Rock mass characterization; Geotechnical Engineering and Engineering Geology; Geology; Civil and Structural Engineering
English
2016
49
11
4303
4318
reserved
Agliardi, F., Sapigni, M., Crosta, G. (2016). Rock Mass Characterization by High-Resolution Sonic and GSI Borehole Logging. ROCK MECHANICS AND ROCK ENGINEERING, 49(11), 4303-4318 [10.1007/s00603-016-1025-x].
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/10281/131014
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