News Release

March 18, 2024

RTRI Develops and Puts into Practical Use
Seismic Reinforcement Method for Bridge Abutments
Using Ground Reinforcing Nails
and Available Even in Narrow Places
The Railway Technical Research Institute (RTRI) developed a “seismic reinforcement
method for bridge abutments using ground reinforcing nails” (Fig. 1) as an effective seismicreinforcement method which can be performed while minimizing the workspace in front sideof bridge abutments. This method eliminates the need for extensive work starting from thefront side of the abutment as in the past and enables economical design according to therequired seismic performance levels.
We hereby report that this method has been used for the first time in the seismic
reinforcement of a bridge across railways.

Ground Reinforcement
MaterialAbutment

Joining Walland Abutment

WallMethod Which Can Be
Applied From the Side ofthe Back Embankment

Fig. 1 Overview of Seismic Reinforcement Method for Bridge Abutments
Using Ground Reinforcing nails
1. Background of Development
In past earthquakes, many cases of damage (Fig. 2) have been reported in which horizontal
displacements and tilting of abutments caused settlement of the abutment backfill. Sincesuch damage can cause track deformation and significantly reduce safety during train
running, seismic reinforcement of existing abutments has been conducted so far by using
supporting strut (reinforcing members installed between abutments) and ground anchors(tensile materials such as high-strength steel, Fig. 3).

News Release

March 18, 2024

However, these methods require a wide workspace in front of an abutment, making it difficult
to perform seismic reinforcement in narrow places such as bridges across railways and those
across roads in urban areas.
Therefore, the RTRI has developed an effective seismic reinforcement method for abutmentsof bridges built in such locations, a "seismic reinforcement method for bridge abutments
using ground reinforcing nails", which can be applied from the side of the abutment backfill
without obstructing the front side of the abutment.

橋桁
橋台
Abutment
滑動・傾斜

Front Faceof Abutment

沈下
Settlement
背面盛土

Back Embankment

Strut

Horizontal Displacements
and Tilting

Ground Anchor

Fig. 2 Example of Damage to Bridge

Fig. 3 Example of Conventional Seismic

Abutment in Past Earthquakes

Reinforcement of Abutment

2. Overview and Major Characteristics of the Method
This method can be applied from the side of the abutment backfill using ground reinforcing
nails and reinforced concrete walls without obstructing the front side of the abutment.
This method integrates abutments, walls, and ground reinforcing nails to improveseismic resistance and reduce horizontal displacements and tilting of abutments as well
as settlement of the abutment backfill.

This method reinforces the abutment by placing ground reinforcing nails from the sideof the abutment backfill, eliminating the need for extensive work starting from the front
side of the abutment and simultaneously reinforcing the abutment backfill.

With this method, the effectiveness of seismic reinforcement can be adjusted by varying
the quantity of ground reinforcing nails. This allows economical design according to therequired seismic performance levels (Fig. 4).

News Release

March 18, 2024
Installment of H-Shaped
Steel Beam and the Like

Reinforced
Concrete Wall
GroundReinforcement
Materials

Abutment(a) Reinforcement Effect: Large(Three-Row Reinforcement)
Fig. 4GroundReinforcement
Materials

Abutment(b) Reinforcement Effect: Small(One-Row Reinforcement)

Example of Economical Design According to the Required Seismic
Performance Levels

3. Example of Practical Use
This method was first used in the seismic reinforcement of the bridge over the Odawara Lineof Odakyu Electric Railway Co., Ltd. (Construction completed in March 2023, Fig. 5).
Abutment

Reinforced Concrete Wall(a) Construction Status of the Site
Railway
CommercialLine

BridgeGirderReinforced Concrete Wall
Earth-Retaining
Steel Sheet Pile

Back Embankment
Abutment

GroundReinforcement
Materials(b) Plane View(c) Cross-Sectional View

Fig. 5 Overview of Practical Use Example