Practical criteria for assessment of horizontal borehole instability in saturated clay

Practical criteria for assessment of horizontal borehole instability in saturated clay Horizontal borehole instability raises concern due to negative impacts on success of drilling, reaming and pipe installation during Horizontal Directional Drilling. Shear failure (blow-out) and tensile failure (hydraulic fracture) are the two main failure mechanisms controlling borehole instability in saturated clay. Criteria for categorizing shear failure versus tensile failure are given which are functions of the ratio of undrained shear strength to vertical effective stress Su/σv′ and the Lateral Earth Pressure Coefficient at Rest K0′. Given that Su/σv′ and K0′ can be expressed as a function of soil parameters like friction angle, Over Consolidation Ratio (OCR) and Liquidity Index (LI), new forms of these criteria are developed for situations where Su/σv′ and K0′ cannot be obtained directly. It is confirmed that tensile failure generally controls in brittle clays like heavily overconsolidated and/or low liquidity index materials. Cases from the laboratory and the field as reported in the literature are used to examine the effectiveness of the new criteria, with inconsistency between theory and the physical evidence explained. http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png Tunnelling and Underground Space Technology Elsevier

Practical criteria for assessment of horizontal borehole instability in saturated clay

Loading next page...
 
/lp/elsevier/practical-criteria-for-assessment-of-horizontal-borehole-instability-sMpdHqmGAR
Publisher
Elsevier
Copyright
Copyright © 2018 Elsevier Ltd
ISSN
0886-7798
D.O.I.
10.1016/j.tust.2018.02.002
Publisher site
See Article on Publisher Site

Abstract

Horizontal borehole instability raises concern due to negative impacts on success of drilling, reaming and pipe installation during Horizontal Directional Drilling. Shear failure (blow-out) and tensile failure (hydraulic fracture) are the two main failure mechanisms controlling borehole instability in saturated clay. Criteria for categorizing shear failure versus tensile failure are given which are functions of the ratio of undrained shear strength to vertical effective stress Su/σv′ and the Lateral Earth Pressure Coefficient at Rest K0′. Given that Su/σv′ and K0′ can be expressed as a function of soil parameters like friction angle, Over Consolidation Ratio (OCR) and Liquidity Index (LI), new forms of these criteria are developed for situations where Su/σv′ and K0′ cannot be obtained directly. It is confirmed that tensile failure generally controls in brittle clays like heavily overconsolidated and/or low liquidity index materials. Cases from the laboratory and the field as reported in the literature are used to examine the effectiveness of the new criteria, with inconsistency between theory and the physical evidence explained.

Journal

Tunnelling and Underground Space TechnologyElsevier

Published: May 1, 2018

References

You’re reading a free preview. Subscribe to read the entire article.


DeepDyve is your
personal research library

It’s your single place to instantly
discover and read the research
that matters to you.

Enjoy affordable access to
over 12 million articles from more than
10,000 peer-reviewed journals.

All for just $49/month

Explore the DeepDyve Library

Unlimited reading

Read as many articles as you need. Full articles with original layout, charts and figures. Read online, from anywhere.

Stay up to date

Keep up with your field with Personalized Recommendations and Follow Journals to get automatic updates.

Organize your research

It’s easy to organize your research with our built-in tools.

Your journals are on DeepDyve

Read from thousands of the leading scholarly journals from SpringerNature, Elsevier, Wiley-Blackwell, Oxford University Press and more.

All the latest content is available, no embargo periods.

See the journals in your area

Monthly Plan

  • Read unlimited articles
  • Personalized recommendations
  • No expiration
  • Print 20 pages per month
  • 20% off on PDF purchases
  • Organize your research
  • Get updates on your journals and topic searches

$49/month

Start Free Trial

14-day Free Trial

Best Deal — 39% off

Annual Plan

  • All the features of the Professional Plan, but for 39% off!
  • Billed annually
  • No expiration
  • For the normal price of 10 articles elsewhere, you get one full year of unlimited access to articles.

$588

$360/year

billed annually
Start Free Trial

14-day Free Trial