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
