The use of shear wave velocities determined in down-hole (Vs vh) and cross-hole (Vs hv) tests for the evaluation of K0 in soils

• Type: Article in International Scientific Journal
• Date: 2005

Authors

Viana da Fonseca, A (Author) FEUP; Cristiana Ferreira (Author) Other; Jorge Manuel C. Machado de Carvalho (Author) FEUP

Journal

Title: Solos e Rochas

Vol. 28

Pages: 271-281

ISSN: 0103-7021

Publisher: Associacao Brasileira de Mecanica dos Solos

Indexing

ISI Web of Knowledge

Scopus - 8 Citations

Other information

Authenticus ID: P-007-EYE

Abstract (EN): The measurement of horizontal at rest stresses in natural grounds is a very difficult task. The drawbacks of the current techniques - even considering the most complex ones, such as the self-boring pressuremeter, and the most advanced interpretation analyses - are usually associated with the processes of installation of the instruments or equipments in the specific locations where this evaluation is required (very often at deep ground levels). Recent trends in use and interpretation of seismic tests, especially those performed in boreholes, have provided some confidence on the estimation of K0,. The basic principle of the methodology relies on the independence of the relation between horizontally and vertically polarized shear waves - measured during direct seismic tests (such as Cross-Hole, CH or Down-Hole, DH) - and the corresponding principal stress acting in the same direction. The at rest coefficient of the earth pressure is therefore a relation between these velocities, taking into account the exponential dependence of each of the velocities with those stresses, which can be derived from calibration laboratory tests over the same soil in undisturbed conditions. An experimental investigation on a typical weathering profile of residual (saprolitic) soil from granite was conducted, in order to complete some recently published data, which preliminarily supported the methodology. This will be hereby presented, after introducing the bases of the methodology and the first experimental results. These results are based on laboratory triaxial tests (with bender elements for measuring seismic wave velocities) over good quality undisturbed samples taken from boreholes that were specifically executed for the seismic tests (DH, with the purpose of determining the velocity of shear waves vertically propagating and horizontally polarized, Vs vh, and CH, using a classical hammer with vertical impact, for the determining the velocity of shear waves horizontally propagating and vertically polarized, Vs hv).

Language: English

Type (Professor's evaluation): Scientific