Crimping prefabricated vertical drains

Q: Can you enlighten me of any work related to the crimping of prefabricated vertical drains (PVD) as a result of soil consolidation and settlement of harbor sludge or dredge spoil? We are anticipating 3 feet (1 m) of settlement in 30 feet (10 m) of sediment (sludge/spoil).

A: I would recommend the following two papers on the subject:

Cortlever N.G. (1983). “Investigation into the behavior of plastic drains in Rotterdam Harbour sludge.” Geotechnics Holland BV) 1-16.

Lawrence, C. A., and Koerner, R. M. (1988). “Flow behavior of kinked strip drains.” Proc., Geosynthetics for Improvement, New York, ASCE, 22–39.

Your 10% total strain is not worrisome. If you go above 25% localized strain, things get interesting for some PVDs. The core could break, and then transmissivity would be drastically reduced.

Please check out the ASTM standards available for PVD. The pertinent ones are as follows:

ASTM D6917 Standard Guide for Selection of Test Methods for Prefabricated Vertical Drains PVD 

ASTM D6918 Standard Test Method for Testing Vertical Strip Drains in the Crimped Condition ASTM D7498 Standard Test Method for Vertical Strip Drains Using a Large Scale Consolidation Test