Techno Press
Techno Press

Geomechanics and Engineering
  Volume 6, Number 4, April 2014 , pages 377-389
DOI: https://doi.org/10.12989/gae.2014.6.4.377
 


Vacuum distribution with depth in vertical drains and soil during preloading
Abdul Qudoos Khan and G. Mesri

 
Abstract
    The vacuum consolidation method which was proposed by Kjellman in 1952 has been studied extensively and used successfully since early 1980 throughout the world, especially in East and Southeast Asia. Despite the increased successful use, different opinions still exist, especially in connection to distribution of vacuum with depth and time in vertical drains and in soil during preloading of soft ground. Porewater pressure measurements from actual cases of field vacuum and vacuum-fill preloading as well as laboratory studies have been examined. It is concluded that (a) a vacuum magnitude equal to that in the drainage blanket remains constant with depth and time within the vertical drains, (b) as expected, vacuum does not develop at the same rate within the soil at different depths; however, under ideal conditions vacuum is expected to become constant with depth in soil after the end of primary consolidation, and (c) there exists a possibility of internal leakage in vacuum intensity at some sublayers of a soft clay and silt deposit. A case history of vacuum loading with sufficient subsurface information is analyzed using the ILLICON procedure.
 
Key Words
    vacuum consolidation; vacuum pressure distribution; preloading; ground improveme
 
Address
(1) Abdul Qudoos Khan:
National University of Sciences and Technology, H-12, Islamabad, Pakistan;
(2) G. Mesri:
University of Illinois at Urbana-Champaign, USA.
 

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