High-Energy Absorption
Rockfall Protection Construction

TOKYO ROPE MFG. CO., LTD.
TOKYO ROPE MFG. CO., LTD.
NIHONBASHI FRONT BLDG. 6-2 NIHONBASHI 3-CHOME CHUO-KU TOKYO 103-8306 JAPAN
Tel.: + 81 3 6366 7789, Fax: +81 3 3278 6870

TOKYO ROPE ENGNEERING LLC.
Build 28 Leninskaya Sloboda str., 26 Moscow, 115280, Russia
Tel.: +7 495 645 04 03, Fax: +7 495 645 04 09

TOKYO ROPE ALMATY LLP.
497, Krasnogvardesky trakt, Almaty city, 050030 Republic of Kazakhstan
Tel.: +7 727 290 3329

TOKYO ROPE MFG. CO., LTD.

http://www.tokyorope.co.jp/english
1710-AVN-EN

Curtain Net method can absorb rockfall energy
with the whole wire net, which provides
high-energy-absorption performance.
With the Curtain Net, struts and suspension ropes are not installed on the slope intended to draw
falling rocks, but unique robust struts are installed on both stable sides less prone to rockfall and are
secured by suspension ropes and stay ropes. With this arrangement, falling rocks do not strikedirectly on the struts or suspension ropes, but the rockfall energy is absorbed only by the curtain as
it is an elastic body. Thus, it is a high-energy absorbing, rockfall protection construction method.

12

34

Features
Tough and excellent in absorbing rockfall energy

Main rope

Reinforcing rope

The horizontal ropes along the top of the curtain and strut suspension ropes are stronger and more
flexible than the wire ropes used in conventional pocket-type rock nets. Besides, the vertical andhorizontal ropes (both main and reinforcing ropes) are placed densely, so that falling rocks of large
size are received integrally by both the rope and net members together, rather than by the net
alone.
The larger deal load of the curtain means a greater difference in energy before and after collision,
which results in substantial increase in the capacity to absorb rockfall energy.

Struts can be placed wider apart
Unlike the conventional pocket-type rock net, strut-to-strut intervals can be increased.
Consequently, struts can be installed on stable locations, avoiding dangerous slope and swamp
areas susceptible to rockfall and unstable cliffs. This arrangement prevents falling rocks from striking
directly on the struts and suspension ropes. On undulating slopes, the undulation can be utilized,that is, anchors can be installed directly in stable ground to extend the top horizontal top ropes toinstall the curtain.

5

Horizontal rope

Strut

Strut

Prone to less damage and easy in maintenanceThe curtain that receives falling rocks is less prone to damage because
its wire ropes and nets are composed of strong and flexible materials.
In addition, falling rocks are guided more desirably to the foot ofslope than in the pocket-type rock net, so that accumulated rocks canbe removed more easily.

High corrosion resistance and durability
High durability versions provide an expected service life of more than
50 years in mountainous areas.
Excellent corrosion resistance and durability result from thegalvanization on all members. Wires, such as those used in wire nets
and wire ropes, which are low in plating coating weight, are appliedwith zinc-aluminum alloy plating to improve corrosion resistance anddurability.

It is not desirable that important facilities built to prevent rockfall
accidents loose their function in short times due to corrosive
deterioration of any particular component member. Based on thisidea, standard plating specifications assure at least 50 years ofcorrosion resistance in mountainous areas, which are typical locations
for such facilities.

Rocks falling from high elevations can be received securely

Environmentally compatible (Toff-coated) version

The struts supporting the curtain are tall at 2.5 to 8.0 meters and form a large opening in the upper
pocket, which reliably accommodates rocks bounding down from high elevations.

“Toff-coated products” are offered as environmentally compatible versions, which are applied withmodified saturated polyester resin coating on the plated surface. The coating film of these products
provides resistance to peeling, resistance to scratches, and high adhesiveness, which together serve
to prevent salt damage. The Toff-coated version also features acid/alkali resistance that has not beenachieved by metal-based rust prevention. Furthermore, the film strength and elongation provide
high reliability for the coating of deformation-susceptible products such as wire rope and wire net.
When the Toff-coating is applied to winding grips, the power of fixing with the rope remains
conformant to the standard value.

6

Example of construction

Curtain Net

Curtain Net

7

The construction site: Tokushima Prefecture, Japan (CN-5.0)

The construction site: Chiba Prefecture, Japan (CN-5.0)

Curtain Net

The construction site: Chiba Prefecture, Japan (CN-4.0)

Curtain Net SuperThe construction site: Hiroshima Prefecture, Japan (CN-S)

8

CURTAIN NET
The models are CN-5.0ZA and CN-4.0ZA for rhombus wire nets of 5.0φ and 4φ wires, respectively, platedwith zinc aluminum alloy, and CN-5.0G and CN-4.0G for rhombus wire nets of galvanized element wires.
Further, Model TF refers to nets applied with Toff-coating over the galvanized surface.
When a net of Model 5.0 uses top horizontal ropes and strut suspension ropes of 7x7 30φ, it is referred toas Model CN-5.0ZA (G, TG)-30.

Model CN-5.0ZA (G, TF) Model CN-4.0.0ZA (G, TF)

Model CN-5.0ZA (G, TF)-30

Model

Model

Wire net
Top horizontal rope
Vertical/horizontal ropes
Vertical/horizontal reinforcing ropes
CN strut (with ladder)
Strut suspension rope
Strut side stay rope
Anchor fitting
TR Cement Jaw Anchor
FR anchorSaddle (for FR anchor)
Root anchor
Turnbuckle J&E
Turnbuckle E&E for Strut connection
Wire grip
ThimbleWinding grip
Suspension fitting
Cross grip
Coupling coil

Model CN-5.0ZA (G, TF)

Model CN-4.0ZA (G, TF)

5.0φ×50×50
7×7 24φ
3×7 18φ
3×7 14φ
H‐200×200×8×12, 2‐M33×1200
7×7 24φ
3×7 18φ25ｔ×450×450, 4‐M30×1200
M33×1200
FRC190 7×7 30φ 6.0m
16×600×1000
114.3φ×4.5×1800
1・1/2×419（38φ）
1×350（25φ）
1×350（25φ）
F24-25
A‐28For 18φ
For 14φ
For 24φ
4.5ｔ×60×75
4.0φ×70×300

4.0φ×50×50
7×7 20φ
3×7 16φ
3×7 12φH‐175×175×7.5×11, 2‐M30×1200
7×7 20φ
3×7 16φ25ｔ×450×450, 4‐M27×1200
M33×1200
FRC130 7×7 30φ 5.0m
16×600×1000
114.3φ×4.5×1800
1・1/2×419（38φ）
1×350（25φ）
1×350（25φ）
F20-22
A‐22For 16φ
For 12φFor 20φ4.5t×60×75 and 3t×60×60
4.0φ×70×300

Model CN-5.0ZA (G, TF)-30
Wire net
Top horizontal rope
Vertical/horizontal ropes
Vertical/horizontal reinforcing ropes
CN strut (with ladder)
Strut suspension rope
Strut side stay rope
Anchor fitting
TR Cement Jaw Anchor
FR anchor
Saddle (for FR anchor)
Root anchor
Rigging screw
Turnbuckle J&E
Turnbuckle E&E for Strut connection
Wire grip
ThimbleWinding grip
Suspension fitting
Cross grip
Coupling coil

5.0φ×50×50
7×7 30φ
3×7 18φ
3×7 14φ
H‐200×200×8×12, 2‐M33×1200
7×7 30φ
3×7 18φ25ｔ×450×450, 4‐M33×1350
M33×1200
FRC290 7×7 30φ 8.5m
16×６００×1000
114.3φ×4.5×1800
Nominal 36
1×350（25φ）
1×350（25φ）
F30-32
A‐34For 18φ
For 14φ
For 30φ4.5ｔ×60×75
4.0φ×70×300

Note: All parts are galvanized. For standard versions (ZA), the wire nets, wire ropes, and winding grips, which are low in plating coating weight, are plated with a highly durable alloyof zinc and 10% aluminum. For TF versions, members with a plating coating weight of 550 g/m2 or more (HDZ-55) are applied with powder coating baking.

Note: All parts are galvanized. For standard versions (ZA), the wire nets, wire ropes, and winding grips, which are low in plating coating weight, are plated with a highly durable alloyof zinc and 10% aluminum. For TF versions, members with a plating coating weight of 550 g/m2 or more (HDZ-55) are applied with powder coating baking.

Full scale weight impact tests

Selection Chart

Model CN-5.0ZA
1000

1000

Model CN-5.0

800

Hn=24m L=18m

700

Hn=18m L=18m

600

Hn=12m L=18m

500
400
300
200
10000

Hn=24m L=18m

Hn=18m L=18m
5.0

10.0

Hn=24m L=18m

800
700

Hn=18m L=18m

600

12

Hn=12m L=18m

500
400
300

32000

Hn=12m L=18m

Rockfall load W (kN)

The test confirms that a descending horn-shaped concreteplumb bob(10kN) from the upper chute with revolving
movement (plumb bob energy 378kJ) collided with theCurtain net construction and it catches the plumb bob
without being penetrated.

Model CN-5.0-30

900

Total absorption energy ET (kJ)

Total absorption energy ET

900

Model CN-4.0

15.0

Hn = curtain height; L = curtain length

0

5.0

10.0

15.0

Rockfall load W (kN)

20.0

25.0

Hn = curtain height; L = curtain length

After the impact

910CURTAIN NET
Structure of Curtain Net
CN-5.0Standard structuraldevelopment diagram

Strut
PL-25t×270×450ｈ

Strut height2.5200300450ｈ（m）
3.0
3.5f+500

Ladder φ194.0
4.5
5.0

H-200×200×8×125.5200

270

6.5

6000

7.0
7.5

1000

TR Cement Anchor, complete: with 2 nuts;
and washers with reinforcing pipe
2-M33×1200

8.06000

Hn6.06000

Underground cast-in anchor for strut foundation

Turnbuckle

PL-19t×950×950

J&E 1・1/2（38φ）
×419
38950

1000

1000
3000

3000

3000 3000

3000

3000
L

3000

3000

3000

3000

3000

3000
L21000

3000

419

950

1000

2000

Parts list
Symbol

24350

600

0150

000
4500
4000

Anchor fitting

246

Groutfor 24φ 2PL-12t×150×246

StrutSpacerRoot anchor

Vertical rope

FR anchor 7×7 30φ

Verticalreinforcing rope

Cast-in anchor

Suspension rope 7×7 24φ

f+500

450300

SaddleWire grip F24-25 Thimble A-28

Top horizontal rope 7×7 24φ

150

Anchor fitting

Vertical rope

Turnbuckle J&E 1・1/2（38φ）×419

Suspension fitting

6050

Verticalreinforcing rope

Top horizontal rope/
suspension rope

Top horizontal rope
7×7 24φ

J&E M24×350

114.3φ×4.5t

FR anchor FRC-190

450Part name

SymbolAnchor fitting
TR Cement Jaw Anchor
Turnbuckle
Wire grip
Winding grip
Suspension fitting
Cross grip
Coupling coil

300

Symbol1000300

Root anchor
114.3φ×4.5-1800

Thimble A-20
Wire grip F-18

Hn2PL-6×200×300

TR Cement Jaw Anchor
M33×1200

00

18

Horizontal rope 3×7 18φ
Winding grip
For 18φ - 1350

TR Cement Jaw Anchor

Guide rope 7×19 18φ

TR Cement Anchor,
complete: with 2 nuts;
and washers withreinforcing pipe
M30×1200

M331200

Strut side stay rope
3×7 18φ

25 200Part name

Wire net
Top horizontal rope
Vertical rope
Horizontal rope
Vertical reinforcing rope
Horizontal reinforcing rope
Strut
Strut suspension rope
Strut side stay rope

1200

Note: Separate specifications apply if snow load is taken into consideration.

1112

CURTAIN NET SUPER

Structure of Curtain Net Super

This model comprise a rhombus wire net of 5.0φ element wires plated with zinc-aluminum alloy with two
top horizontal ropes of 7x7 ZA/O 30φ. In addition, the model using wire nets, wire ropes, winding grips,
and coupling coils, all parts galvanized is Model G and the one applied with Toff-coating over thegalvanized surface is Model TF.

CNS-S
Standard structuraldevelopment diagram

f+500

Model CNS-S (ZA, G, TF)
Model

Note: All parts are galvanized. For standard versions (ZA), the wire nets, wire ropes, and winding grips, which are low in plating coating weight, are plated with a highly durable alloyof zinc and 10% aluminum. For TF versions, members with a plating coating weight of 550 g/m2 or more (HDZ-55) are applied with powder coating baking.

500
6000
500

6000

500
3000

3000

3000

3000

3000

3000
L

3000 3000

3000

3000

3000

3000
L2

2000

3000

Anchor fitting
Rigging screw, nominal 36

Parts list

Wire grip F30-32 Thimble A-34

Part name

Wire net
Top horizontal rope
Vertical rope
Horizontal rope
Vertical reinforcing rope
Horizontal reinforcing ropeStrut
Strut suspension rope
Strut side stay rope

SymbolPart nameAnchor fitting
TR E Anchor
Turnbuckle
Wire grip
Winding grip
Suspension fitting
Cross grip
Coupling coil

SymbolSuspension rope
Strutf

Suspension fitting
Cross grip
Coupling coil
Coupling coil (for top rope)

500

Top horizontal rope
7×7 30φ
Strut side stay rope
3×7 18φ

HnWinding grip

Hn5.0φ×50×50
7×7 30φ
3×7 18φ
3×7 14φ
H‐250×250×9×14, 4‐M33×1200
7×7 30φ
3×7 18φ
for 30φ 25×450×450, 4‐M33×1350
38φ×1200
FRC‐290 7×7 30φ 8.5m
16×600×1000
114.3φ×4.5×1800
Nominal 36
1×350（25φ）
3×7 18φF30‐32
A‐34for 18φ
for 14φfor 2×30φ
4.5ｔ×60×75
4.0φ×70×300
4.0φ×100×300

6000

Model CNS-S (ZA, G, TF)
Wire net
Top horizontal rope
Vertical/horizontal ropes
Vertical/horizontal reinforcing ropes
CNS strut (with ladder)
Strut suspension rope
Strut side stay rope
Anchor fitting
TR E Anchor
FR anchor
Saddle (for FR anchor)
Root anchor
Rigging screw
Turnbuckle J&E
Joint rope, with both ends worked for Toyolock
Wire grip
ThimbleTR E Anchor
38φ×1200

Full scale weight impact tests
Horizontal rope 3×7 18φ

Model CNS‐S
Model CNS-S（Hn=12m）（Hn=24m）

Hn=24m L=39m

1200

900

Hn=12m L=39m

15

Hn=12m L=24m
2025Rockfall load W (kN)3035

Hn = curtain height; L = curtain lengthｈ（m）
2.5
3.0
3.5
4.0Ladder φ192PL-25t×350×600

Hn=12m L=30m

13Strut height

Hn=24m L=24m

600

00ｈ

1300
400 300 400
700

Hn=24m L=30m

Winding grip for 18φ

Strut350

Total absorption energy (kJ)The test confirms that a descending horn-shaped concrete
plumb bob (25kN) from the upper chute with revolving
movement (plumb bob energy 1,076kJ) collided with theCurtain net construction and it catches the plumb bob
without being penetrated.

Model CNS-S

250

1500

4.5
5.0
H-250×250×9×14

5.5250

Selection Chart

6.0
6.5
7.0

TR Cement Anchor, complete: with 2 nuts;
and washers with reinforcing pipe
4-M33×1200

7.5
8.014