Introduction

What does RRR mean?

RRR stands for “Reinforced soil Road structures with Rigid facing”
RRR are reinforced structures that include embankments, retaining walls,
water-front structures, bridge abutments, bridge systems etc. constructed for railways,
highways and others.
RRR reinforced soil structures comprises four sub-systems, A to D：

Category	Structure type
RRR-A	Reinforced-soil bridge abutments & bridge systems
RRR-B	Geosynthetic-Reinforced Soil (GRS) retaining walls
RRR-C	Nail-Reinforced Soil (NRS) retaining walls
RRR-D	GRS structures to prevent water-front disasters
OHTERS	GRS Box Culvert / GRS Tunnel Entrance

RRR-AReinforced-soil bridge abutments & bridge systems

・GRS Bridge Abutments, using bearings to support a simple girder.

・GRS Integral Bridges and NRS Integral Bridges structurally integrating the girder respectively, to the top of FHR facing connected to GR backfill, and to the top of RC abutment connected to nailed backfill.

RRR-BGeosynthetic-Reinforced Soil (GRS) retaining walls

・GRS retaining walls (RWs) with full-height rigid (FHR) facing

・GRS RWs with FHR facing can support railway tracks or roads arranged close to the wall face. They can also support continuous RC slab railway tracks and external loads acting on, or close to, the facing.

RRR-CNail-Reinforced Soil (NRS) retaining walls

・Natural slopes and embankment slopes are cut to vertical walls by reinforcing slopes with medium to large diameter nails using full-height rigid facing.

RRR-DGRS structures to prevent water-front disasters

・Water-front GRS structures to prevent and mitigate disasters caused by scouring, erosion and overtopping flow by flood, storm and tsunami.

GRS Tunnel Entrance

GRS Box Culvert

Others

Brief history

1981

Start of basic research at Institute of Industrial Science, the University of Tokyo

1987

Start of research at Railway Technical Research Institute, Japan

1987

Application for the first patent (15 July)
Patent No.1870191 for "Embankment stabilization method by soil-reinforcing and structures constructed by this method"

1987

First prototype of GRS RW structure by RRR-B technology at Tennoji station, Osaka (August)

1991

Establishment of Association of RRR Construction System (12 July)

1994

Certificate of technical evaluation (No.0505) by Japan Institute of Country-ology and Engineering (31 March) : RRR-GRS Retaining Wall system (RRR-B system)

2002

Certificate of technical evaluation (No.1403) by Advanced Construction Technology Center (28 November): Radish Anchor (Large-diameter nails) method (RRR-C system)

2005

Publication of a book entitled by "All of the new reinforced soil retaining walls" by General Civil Engineering Institute Co.,Ltd. [Sougou Doboku Kenkyujo] (25 October)

2009

Establishment of Radish Anchoring Section (June)

BASIC PRINCIPLES

RRR structures are hybrid structures integrating a rigid facing and a reinforced soil body. The RRR structures can exhibit outstanding performance by combining advantageous features of rigid facing and reinforced soil body.
The basic principles of the RRR construction system are shown below:

Advantages of rigid facing

★High strength & high rigidity

★High durability