DEEP COMPACTION OF NON-COHESIVE SOILS BY THE USE OF EXPLOSIVES

A method of compacting loose sands, using explosives to increase ground stability before construction, is described. The technique can be used on land, under water, and in nearshore marine conditions. A wash boring is performed to a predetermined depth and a charge, whose intensity is a function of its depth, is placed and detonated. The soil around the detonated charge is liquefied and resettles at a higher density. The choice of the spacings and number of borings, the intensity of the charges, and the sequence of the detonations are very important. Higher density and a more homogeneous layer structure are achieved. Details are given of the use of the method, underwater, to compact an area of 17000 sq m of dumped sand as the foundation layer for the breakwaters of a new outer harbour at zeebrugge, Belgium. Cpt tests were used to monitor and control the effectiveness of the compaction, and the results show a considerable increase in cone resistance in the dumped sand layer after detonation. In the underlying sand layer which contained many thin clay seams, only the sand zones were compacted; the clay seams were unaffected. The method gives a high production rate with a limited amount of equipment and personnel, but requires highly skilled and experienced rig operators and blasting specialists. In nearshore applications a small jack-up platform may be used.

• Corporate Authors:

  MINISTRY OF PUBLIC WORKS, DEPARTMENT OF WATERWAYS

  Bruxelles,   Belgium 

  SERVICE

  ,    
• Authors:
  • -
• Publication Date: 1983-10

Language

• English

Media Info

• Pagination: 3 p.

Subject/Index Terms

• TRT Terms: Compaction; Density; Depth; Granular soils; Methodology; Presplitting; Sand; Tests
• Geographic Terms: Belgium
• Subject Areas: Construction;

Filing Info

• Accession Number: 00487738
• Record Type: Publication
• Source Agency: Transport and Road Research Laboratory (TRRL)
• Files: ITRD, TRIS
• Created Date: Sep 30 1989 12:00AM