Section 651. ROCK FALL PROTECTION Description 651.01

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Nov 29, 2013 (3 years and 11 months ago)

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Section 651.


ROCK

FALL
PROTECTION


Description


651.01
This work consists of designing, furnishing,

and installing
permanent rock

fall fence
,
rock fall netting, pinned rockfall netting, attenuators and sculpted shotcrete
to restrain rock fall.


This

work includes any incidental work to install the rock

fall fence
and wire mesh netting
system
s
. This includes, but is not limited to the following:


(a)

E
xcavation

to install rock

fall fence,
fence posts

and wire mesh netting
.


(b)
Concrete required to

set rock

fall fence post foundations.


(c)
Post and wire rope foundations


Material


651.02

Conform to the following Subsection:



Rock

fall fence








710.12



Rock fall netting








720.04


Submit the following certificates to the CO at least two
weeks prior to beginning work.


(a)

Certificates stating that samples for testing are from normal stock, which will be used in
the work.


(b)

Manufacturer’s certified test results of set time, shelf life, and compressive strength for
each type of grout to be used.


(c)

Certified reports, not more than one year old, that the product to be supplied equals or
exceeds these specifications.


Design
Requirements


651.03 Submittals
.
Design and assemble the
rock fall fence system in accordance with the
contract documents and the manufacturer’s standards and requirements.
Submit complete design

and detail drawings of the following:


(a
) The rock fall
fence system showing full, detailed dimensions of all component parts of
the system to the CO for approval according to Subsection 104.03.
Design a system that is
capable of absorbing impact design loads for a kinetic energy
(Design Impact Energy)
specifi
ed in the plan drawings and specifications and be able to absorb the ultimate impact
loads without allowing the rock to pass. Design a system that will enhance, and not impede
,

future revege
tation efforts planned for the S
ite.


(b)

The rock fall netting

system showing full, detailed dimensions of all component parts of
the system to the CO for approval according to Subsection 104.03
,

prior to purchase of the
material.


(c
)
Supply documentation certifying the rock fall fence and rock fall netting syste
ms are

designed for a minimum service

life of 75 years.


Construction Requirements


651.04 General.

Safety of the work is the responsibility of the Contractor. Perform the work in
a manner to minimize hazards and exposure to the public, construction personnel, and
equipment.
Install
rock

fall fence and rock fall netting systems

in accordance with the
m
anufacturer’s standards and requirements. Install
at the locations designated in the plan
drawings or as directed and approved by the CO.


(a)

Submit shop drawings to the CO in accordance with Subsection 104.03. Refer to data in
the Soils and Foundation
Report. One set of drawings marked with any suggested
modifications or changes will be returned to the Contractor.


(b)


Certify that the designed system has demonstrated a satisfactory performance in similar
applications and capacities.


(c)


Provide documentati
on that certifies that the system design can absorb the required
ultimate load.


Regularly engage the manufacturer of the rock fall fence and rock fall netting systems in the
design and assembly of rock fall fence and rock fall netting systems. Use a manu
facturer with a
minimum of three years of documented experience with manufacturing of such systems used in a
similar application and capacity. Supply manufacturer’s written evidence demonstrating
certification of a quality assurance program.


Properly mar
k all transported materials to identify system components with the approved shop
drawings.


651.05

Excavation and Preparation.



Perform all excavation and foundation preparation work in accordance with Sections 107 and
209.


Carefully
shape

material around the vicinity of the rock

fall fence system to match the existing
ground surface and to prevent the creation of jumping ramps for falling rocks. If spreading
excess excavated material in this area will create an increased rock

fall or inst
ability risk, remove
material to designated disposal area.


Perform foundation work for the columns and rock anchors in accordance with the plan
drawings. Space fence columns, centerline to centerline, in accordance with the plan drawings.


651.06 Syste
m Installation.


Erect the foundations, anchors, and columns in accordance with the plan drawings. Fence
columns should not vary from the indicated pitch or from vertical by more than 2 inches from
top to bottom of the column and should not deviate more t
han
+

3 inches from centerline to
centerline of the columns.


Install and fasten support ropes in accordance with manufacturer’s instructions. Do not fasten
support ropes until the columns are properly set. Tension all ropes as necessary to eliminate
sla
ck, and tension the support ropes until there is no sag in the ropes.


Label all material and the system components clearly per manufacturer. Ship and handle the
material according to manufacturer’s recommendations.


Install the rock fall netting system u
nder the supervision of a qualified professional engineer and
in accordance to manufacturer’s recommendations. Use seam rope to fasten the mesh panels to
each other and to lace the mesh to the top support rope.


651.07 Shipping.
P
roperly label all mater
ials prior to shipping to the job site to easily identify
the system components with the manufacturer’s drawings to minimize installation time. Su
pply
spare parts for the system
.


651.08

Testing.
Verify that anchors have a pull out strength of at least 6 tons
(or minimum
recommended by the manufacturer)
by conducting pullout on 20 percent of the total number of
anchors.
Provide pullout test load that is 1.2 times the minimum pullout strength.
Tes
t against a
temporary yoke or load frame with no part of the yoke or load frame within 3 feet of the anchor.
If more than 25 percent of the tested anchors fail, test all anchors. Replace all failed anchors


651.09

Acceptance.

Material for the rockfall
fence system will be evaluated under Subsections
106.03 and 106.04. Construction of rockfall fence system will be evaluated under Subsections
106.02 and 106.04.


Measurement


651.
10

Measure the Section 651 items listed in the bid schedule according to Su
bsection 109.02.


Payment


651.11

The accepted quantities will be paid at the contract price per unit of measurement for the
Section 651
pay
items listed in the bid schedule. Payments will be full compensation for the
work prescribed in this Section. Se
e Subsection 109.05.



Section 710.

FENCE AND GUARDRAIL


710.12 Rockfall Fence


(a)

Wire rope netting:

Provide straight woven nets with continuous wire rope. Braid nets
with high strength corrosion resistant clips. Provide net wire of high tensile stre
ngth carbon
steel with a nominal 0.157
-
inch diameter and a minimum breaking strength of 257,000
pounds per square inch. Provide wire that is coated with a minimum 4.4 ounces per square
yard of zinc/aluminum super coating.


(b)

Wire mesh:

Provide nets that are covered with chain link mesh material, the latter being
attached to the wire rope netting and fastened with galvanized rings and/or galvanized tie
wire on 24
-
inches centers horizontally and vertically. Provide chain link material th
at is 9
-
gauge minimum, conforms to AASHTO M181
-
90, and is zinc coated in accordance with
A392
-
84, Class 1 Standards.


(c)

Net support columns:

Provide columns fabricated from wide flange structural members
meeting ASTM A36 for preformed steel shapes. Prov
ide columns galvanized with a
minimum of one coat. Column foundation shall be of shear pin assembly instead of direct
buried foundation. All steel shapes shall comply with ASTM A36
-
84 and bolts, nuts and
washers to ASTM A325
-
86.


(d)

Support wire ropes:

Design support wire ropes in accordance with manufacturer’s
specifications. Verify rope diameter and minimum breaking strength are adequate to provide
a safe design with an adequate factor of safety. Provide wire ropes meeting the Federal
Specification

RR
-
W
-
410D or equivalent.


(e)

Rock anchors:

Specify and verify anchor pullout strengths that are adequate to provide a
safe design with an adequate factor of safety and verifiable in the field. Perform verification
test consisting of a pullout test inco
rporating 20 percent of the total number of anchors.
Provide pullout test load that is 1.2 times the minimum pullout strength. If more than 25
percent of the tested anchors fail, test all anchors. Replace failed anchors at no cost to the
government. Pe
rform testing using a temporary yoke or load frame. No part of the yoke or
load frame shall bear within 3 feet of the anchor.


(f)

Miscellaneous materials:

Galvanize a
ll miscellaneous hardware such as wire rope clips,
thimbles, bolts, shackles, etc.

Manu
facturer will
suppl
y

miscellaneous materials

with the
system.


(g)

Corrosion protection:

Provide all materials that are galvanized meeting
the
requirements of ASTM A641

for zinc coated carbon steel wire.




Section 720.

STRUCTURAL WALL AND STABILIZED EMB
ANKMENT MATERIAL



720.04 Rockfall Netting.


(a)
Mesh
. Furnish
galvanized, coated steel
wire mesh consisting of
double twist netting
type, with a maximum tensile strength of 75,000 pounds per square inch per ASTM A

641,
soft temper steel. Provide PVC coating conforming to ASTM A975
-
97, Section 8.2
.

Galvanize in accordance with ASTM A 153.


(b) Net support ropes.

Manufacture rope from galvanized steel wire strand, common
grade, Type 1 coating, conforming to the r
equirements of ASTM A 475
, with a minimum
breaking strength

in accordance with
design requirements and manufacturer’s specifications.



(c) Mesh Pins.

Furnish mesh pins to keep wire mesh within 2 feet of rock face to reduce the
height from which rock fall can occur.


(d)


Rock anchors.
Furnish
bar or
wire rope anchors
. Conform bar anchors to the
requirements of Section 260, Rock Bolts, Grade 75, for ancho
rs. Furnish wire rope
in
accordance with
design requirements and
manufacturer’s specifications.



(e
) Seam rope and fasteners.
Furnish galvanized steel

conforming to ASTM A 475
, with
diameters and minimum breaking strengths in accordance with
design req
uirements and
manufacturer’s specifications.


(f
) Shackles.
Furnish galvanized anchor shackles in accordance with
design requirements
and
manufacturer’s specifications.


(g
) Wire rope.
Furnish galvanized wire rope conforming to Federal Specification RR
-
W
-
410F.


(h
) Miscellaneous material.

Hot dip galvanize nuts, bolts,
shackles
and all other
miscellaneous material associated with the rock

fall
netting
system.


(i
)

Grout.

Use non
-
shrink cement grout for the anchors.


(j)


Bearing Plates.

Furnish steel

bearing plates in accordance

with ASTM A36. G
alvanize
for corrosion protection.