Sample Disturbance: what is it?
The aim of this free webinar is to stimulate a discussion and start a process whereby we can begin to decide on factors which might build to be a disturbance classification.
Both EC7 and BS5930 suggests that there are five quality classes of sample which can be obtained from intrusive ground investigation, some are quite self-explanatory however for strength and deformation testing we are advised to use Class 1 samples.
This webinar will ask what constitutes a class 1 sample – the codes suggest that to obtain class 1 samples we should use techniques such as thin wall sample tubes or rotary coring methods. However, practitioners and laboratory technicians alike will tell you that even with these methods many samples are evidently disturbed and not class 1, it is therefore certain that by using one of these suggested methods that a class 1 sample is not necessarily achieved.
This webinar will look at:
· The sampling process and methods which may provide a class 1 sample
· What constitutes a class 1 sample and how do we recognise sample disturbance
· Are there grades of disturbance what is acceptable
· Should there be a scale to enable technicians and laboratories to recognise and report the degree of disturbance
Attendees can expect to learn:
· The sampling process and what influences sample disturbance
· What makes a class 1 sample and why is it so important
· The differences between the sample classes and the effect on sample behaviour and measured parameters
· How to visually identify sample disturbance
This webinar will be of interest to engineers of all grades; practitioners; specifiers; laboratories and investigation designers.
To participate in this free webinar, select the add to cart and register button, followed by proceed to check-out. Complete your details and click on place order. You’ll receive two confirmation email; one confirming your order and another with your registration link. You won’t be charged to attend this webinar.
Presentations
Sampling methods and sample disturbance and checking up on the disturbance
David Norbury, Director at David Norbury Ltd
We all know we want to have undisturbed samples to examine and test. Do we really want and need this? If so how do we specify what degree of sample disturbance we are prepared to accept? What sampling methods might best be deployed to attain that acceptable level of disturbance? How do we check the recovered samples for disturbance? These matters will be reviewed in the context of the EN Standards.
Sample disturbance in soft clay, causes and how it can be assessed
Tom Lunne, Expert adviser at Norwegian Geotechnical Institute
All natural clays have some structure which may be partly or completely damaged during sampling and sample handling. Soil parameters measured in the laboratory can be strongly influenced by sample disturbance and frequently to such an extent that they are not representative for in situ conditions. In Norway a of set criteria for evaluating sample disturbance of soft clay have been established, and this is now included in national and international guidelines/standards. Examples will be given on how these criteria can be used for practical projects. The range of validity and limitations of these criteria will also be given.
Sample disturbance in stiff clay, can we assess it? What labs can and can’t do!
John J M Powell, Technical Adviser at Geolabs Limited
Following on from soft clays then can we maintain in situ structure and stress state when sampling stiff, overconsolidated clays. In these stiff clays do current sampling methods allow quality samples to be obtained, what is the role of the sampler, the operator, the sample handling and storage in sample disturbance? What assessment can a laboratory make of sample quality, what should they be expected to report? These topics will be discussed and hopefully lead to an open discussion!
This webinar will be of interest to engineers of all grades; practitioners; specifiers; laboratories and investigation designers
- Sampling methods and sample disturbance and checking up on the disturbance
- Sample disturbance in soft clay, causes and how it can be assessed
- Sample disturbance in stiff clay, can we assess it? What labs can and can’t do!
She has worked in the site investigation field for specialist contractors and for design consultancies on many major transport and energy infrastructure schemes, on earthworks design schemes and asset management in the road, rail and energy sectors.
Sally has more recently concentrated on business development and technical management of geotechnical operations within Coffey in the UK and has been the AGS Business Practice Working Group Leader since 2019.
At Geolabs he is responsible for technical output and specifically for developing further the areas of advanced testing of soils and rocks for both land and offshore applications. He is also responsible for managing and developing in-house and collaborative research to advance both equipment and soil behaviour.
He sits on and chairs national and international technical and standards committees on related works.
Assignments have included construction and redevelopment of land, marine and underground works and nuclear licensed sites. With responsibilities incorporating the design, execution and validation of investigation, construction, forensic and remedial programmes. He has provided Expert Witness services on a range of technical, planning and contractual disputes, including presentations at hearings and in court.
