UNE-EN ISO 12958-2:2021

This International Standard specifies a method for determining the constant-head water flow capacity

within the plane of a geotextile or geotextile-related product, using boundary materials and test

conditions of interest. A standard series of test conditions are proposed, involving soil confinement, low

hydraulic gradients, seating times and an array of normal loads.

NOTE 1 The results obtained under this test procedure may not compare with those obtained under ISO

12958 Part 1, even if some of the test conditions are similar.

NOTE 2 Many geosynthetic products can creep under constant load, i.e. see their thickness diminish over

time, which may influence their in-plane water flow capacity. Although a seating time typically greater than the

one used in ISO 12958-part 1 is used, this test does not cover all creep-related issues for drainage geocomposites.

Assessment of long-term flow capacity may require further considerations.

NOTE 3 This procedure may be useful to assess the effect of geotextile intrusion into the drainage core on the

transmissivity of a drainage product, using soil from a particular project as a stress-distribution layer in contact

with the geotextile.

Note 4 There are other test methods which may be more suitable for the characterization of particular

drainage products, such as ISO 18325 for Prefabricated Vertical Drains. It is the responsibility of the user to

assess the limit of this test procedure and select the appropriate test method, and/or test conditions that

adequately reflect the particular needs for his project.

NOTE 5 In this test method, the performance of the product is approached considering soil confinement,

service load and service hydraulic gradient, as well as primary creep. However, other field-related issues will

affect material long-term performance, such as secondary or tertiary creep, chemical or biological clogging,

chemical resistance and durability, installation, backfilling, etc. These issues are covered in separate standards

and must be considered while designing with geosynthetics.