Geosynthetics-Reinforced Soil Structures - Developments from Walls to Bridges-

Geosynthetics-Reinforced Soil Structures - Developments from Walls to Bridges-

Presenter: Prof. Fumio Tatsuoka
Title: Geosynthetics-Reinforced Soil Structures - Developments from Walls to Bridges-
Launching Date & Time: June 10 2020 12:00pm GMT

Download Related Technical Papers of GRS Structures by Tatsuoka et al.

Session Question & Answer [CLOSED]


Can we use polyester geogrids instead PVA geogrids in alkaline environment (fresh concrete touching grids at face)?
How to evaluate geogrids for such applications?

Fumio Tatsuoka

Dear Mr Mohan Krishna Kolli:

We evaluated the durability of several types of geogrid in alkaline environments by performing acceleration tests and confirmed that polyester geogrids are not suitable for long-term use in alkaline environments. Instead, PVA loses little the strength in long-term use in alkaline environments. This is indicated in Fig. 17 of the following paper:
Tatsuoka, F., Tateyama, M., Murata, O. and Tamura, Y. 1994. Geosynthetic-reinforced soil retaining wall structures with short reinforcement and a rigid facing (closure), Proc. of Int. Symposium Recent Case Histories of Permanent Geosynthetic-Reinforced Soil Retaining Walls (Tatsuoka and Leshchinsky eds.), Balkema, pp.323-342.
A copy of this paper can be downloaded from:

Currently, PVA (polyvinyl alcohol) with a PVC protection is used with many GRS structures with full-height rigid facing produced by casting-in-place concrete.

Best regards,

Andrew Jr Zapanta

Dear Tatsuoka-sensei,

The following are my questions:

1) Can we use wire mesh gabions (2.7mm diameter wire and Zinc-coated) to be casted with conrete for the rigid facing? The wire mesh will also be used as the reinforcement element with a distance of 0.50m between the layers of reinforcement.

2) If we use a geogrid and develop a connection system between the geogrid and the wire-mesh gabions (refer to question 1), can this be use for the FHR system?

Thank you in advance,

Best Regards,

Andrew A. Zapanta Jr.

Fumio Tatsuoka

Dear Mr. A. Zapanta Jr.:

Thank you very much for your two questions Q1 and Q2: (A to Q1) In Japan, for better workability, gravel-filled mesh boxes (30 cm-high) are very often used in place of two layers of gravel-filled geogrid-gabions (15 cm-thick) placed on the shoulder of each soil layer between two vertically adjacent geogrid layers (with a vertical spacing of 30 cm).
The followings may be important remarks:

1.Like gravel-filled geogrid gabions, the gravel-filled wire mesh boxes should be wrapped-around with end part of reinforcement layers (i.e., geogrid layers) so that a good permanent connection between the cast-in-place concrete FHR facing and the reinforcement layers is ensured even in case wire mesh boxes lose sufficient strength in a long run. That is, although the wire mesh boxes are treated to prevent rusting, they are not expected as permanent structural component in design. Likewise, we are not using wire-mesh layers as reinforcement layers in place of geogrid layers.

2.A vertical spacing between geogrid reinforcement layers equal to 30 cm is specified aiming at: 1. ensuring monolithic or integrated behaviour of reinforced soil zones that may be reinforced with relatively short reinforcement layers; and 2. enhancing good compaction of backfill by means of two 15 cm-thick lifts. Good compaction of the backfill is essential for stability of reinforced soil structure. Good compaction immediately back of the FHR facing is particularly important: (1) to use the crest of the reinforced backfill immediately back of the FHR facing as roads or railways (particularly those for high-speed trains); and (2) to use the FHR facing as a stable foundation that supports noise barrier, crash barrier, bridge girder and so on.

(A to Q2) My answer is “yes” with remarks depicted in (A to Q1).

I hope that my response is relevant.
Best regards, Fumio TATSUOKA