ISO 24057:2022

INTERNATIONAL ISO
STANDARD 24057
First edition
2022-11
Geotechnics — Array measurement of
microtremors to estimate shear wave
velocity profile
Géotechnique — Mesure en réseau des microtrémors pour estimer un
profil de vitesse des ondes de cisaillement
Reference number
© ISO 2022
All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may
be reproduced or utilized otherwise in any form or by any means, electronic or mechanical, including photocopying, or posting on
the internet or an intranet, without prior written permission. Permission can be requested from either ISO at the address below
or ISO’s member body in the country of the requester.
ISO copyright office
CP 401 • Ch. de Blandonnet 8
CH-1214 Vernier, Geneva
Phone: +41 22 749 01 11
Email: copyright@iso.org
Website: www.iso.org
Published in Switzerland
ii
Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms, definitions, symbols and abbreviated terms . 1
3.1 Terms and definitions . 1
3.2 Symbols and abbreviated terms . 2
4 Equipment . 3
4.1 General . 3
4.2 Sensor . 3
4.3 Time calibration equipment . 4
4.4 Data logger . 4
4.5 Distance and location measuring instrument . 4
4.6 Protective products . 4
5 Survey procedure .5
5.1 General . 5
5.2 Preparation . 6
5.2.1 Desk study . 6
5.2.2 Array design . 6
5.3 Field observation . 6
5.3.1 Huddle test . 6
5.3.2 Setting of sensors. 7
5.3.3 Recording . 7
5.4 Data organization after field observation . 8
5.4.1 Quality control of the microtremor record. 8
5.4.2 Data storage . 8
6 Data Analysis . 8
6.1 Data organization after field observation . 8
6.2 Phase velocity analysis. 8
6.3 Inversion analysis to S-wave velocity profile . 10
6.4 Uncertainty of phase velocity and S-wave velocity profile . 10
7 Reporting .11
7.1 General . 11
7.2 Field report . 11
7.3 Analysis report . 13
Annex A (informative) Example of a figure and a table schematic figure of array
measurement of microtremors .15
Annex B (informative) Example of microtremor records and analysis results .16
Annex C (normative) Array design .18
Annex D (informative) Frequency characteristics of sensors in huddle test .22
Annex E (informative) Examples of good and poor quality microtremor records .23
Annex F (informative) Methods for phase velocity analysis .25
Annex G (informative) Method for inversion analysis to S-wave velocity profile .32
Annex H (informative) Uncertainty .34
Bibliography .38
iii
Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards
bodies (ISO member bodies). The work of preparing International Standards is normally carried out
through ISO technical committees. Each member body interested in a subject for which a technical
committee has been established has the right to be represented on that committee. International
organizations, governmental and non-governmental, in liaison with ISO, also take part in the work.
ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of
electrotechnical standardization.
The procedures used to develop this document and those intended for its further maintenance are
described in the ISO/IEC Directives, Part 1. In particular, the different approval criteria needed for the
different types of ISO documents should be noted. This document was drafted in accordance with the
editorial rules of the ISO/IEC Directives, Part 2 (see www.iso.org/directives).
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. ISO shall not be held responsible for identifying any or all such patent rights. Details of
any patent rights identified during the development of the document will be in the Introduction and/or
on the ISO list of patent declarations received (see www.iso.org/patents).
Any trade name used in this document is information given for the convenience of users and does not
constitute an endorsement.
For an explanation of the voluntary nature of standards, the meaning of ISO specific terms and
expressions related to conformity assessment, as well as information about ISO's adherence to
the World Trade Organization (WTO) principles in the Technical Barriers to Trade (TBT), see
www.iso.org/iso/foreword.html.
This document was prepared by Technical Committee ISO/TC 182, Geotechnics.
Any feedback or questions on this document should be directed to the user’s national standards body. A
complete listing of these bodies can be found at www.iso.org/members.html.
iv
Introduction
This document provides the specifications on the equipment, survey and analysis procedure of array
measurement of microtremors in order to estimate shear wave velocity profile.
This document is intended for use by administrators of infrastructure facilities (public sector
institutions, such as national and local governments, and private institutions), building constructors,
house builders, consultants, academia, and public/private research institutions. The array measurement
of microtremors deliverable described in this document can be useful in various engineering fields such
as the
— estimation of geotechnical site conditions for construction;
— stability assessment of foundations;
— evaluation of the risk for soil liquefaction;
— evaluation/prediction of earthquake ground motions.
Array measurement of microtremors is one of the geophysical measurements using surface waves,
and it is a non-destructive testing method described in an application manual of geophysical methods
[5]
to engineering and environmental problems for estimating S-wave velocity profile from dispersive
characteristics of the surface waves. Reliability of the method has been evaluated by blind tests and
[6],[12]
numerical simulations in several international projects .
The array measurement of microtremors is a passive method using natural and artificial ambient
vibrations. Since power of the ambient vibrations is highly variable from one site to the other, it
will possibly not be applicable to a site where the ambient vibration level is less than internal noise
of measuring instruments. The array measurement of microtremors using vertical ground vibration
to estimate an S-wave velocity profile by processing microtremor records based on the fundamental
mode of Rayleigh waves is the most common surface wave method. In addition to the fundamental
mode, including the processing of higher modes of the Rayleigh waves improves the reliability of
the estimated S-wave velocity profile. However, a procedure for identifying the higher modes from
observed microtremors is not authorized in academics yet. Hence, analysing the higher mode of the
Rayleigh waves is out of scope in this document. Love waves is another type of surface waves extracted
from horizontal ground vibration. Joint use of the Rayleigh waves and the Love waves also improves
the reliability of the estimated S-wave velocity profile. However, the surface wave method using Love
waves is not widely used in practice. Hence, the measurement and the analysing of the Love waves are
out of scope in this document. Therefore, the array measurement of microtremors using vertical ground
vibration and the data analysis of the microtremor records with an assumption of the fundamental
mode of Rayleigh waves are described in this document.
This method provides a vertical S-wave velocity profile. The depth range of the S-wave velocity profile
varies depending on the wavelength of observed s
...