219Rockfall Mesh

Rockfall Mesh

219.1DESCRIPTION

1 This section describes the requirements for furnishing and installing anchors and rockfall mesh on finished backslopes.

219.2MATERIALS

1 Provide materials in accordance with the following:

Materials

Anchors Subsection

822.3 Hardware 822.6 Lacing and Fasteners 822.2 Non-shrink Grout 822.4 Rockfall Mesh 822.1 Wire Rope 822.5

1 Provide mesh in an industry-standard color.

219.3EQUIPMENT—V acant

219.4CONSTRUCTION

219.4.1 General

1 Submittals: Submit the following to the engineer at least 10 working days before beginning work:

to be used, taken from normal stock of the manufacturer. Submit the samples with mill reports indicating tensile yield point, where applicable, and the tensile and punching tests of the rockfall mesh. Submit a color sample of the rockfall mesh to the engineer for final approval.

used on the project

for minimum strength of PVC and metallic coated gabion materials.

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combination of ram, jack, and pressure gauge to be used for testing of the bar or wire rope anchors. Calibrate the stressing ram assembly within 30 days of the initial on-site testing.

schedule; proposed drilling methods; the proposed grout, mix design, or specifications and placement procedure; and the proposed stressing procedure for grouted anchors.

Professional Rope Access Technicians (SPRAT) at Level 1; or as Slope Access Technician Level 1 through the Professional Climbing Instructors Association (PCIA); or document ( provide resume) that they have acquired the equivalent knowledge, skills and abilities required for certification through SPRAT or PCIA in their previous work on rock slopes.

2 Before installing mesh, prune shrubs and trees so that mesh will lie flat. Scale backslopes in accordance with Section 220, Scaling Rock Cuts.

3 Begin installation after the engineer has approved the plan in writing.

4 Maintain and take responsible care for the safety of the work at all times. Perform the work in a manner to reduce hazards and potentially hazardous conditions to the public, construction personnel, and equipment. Schedule placement of the rockfall mesh to ensure safety.

5 Perform all work requiring rope access in accordance with the Code of Federal Regulations 1926.501 B15. Contact the Wyoming Occupational Safety and Health Administration for an interpretation of these regulations and certifications as they apply to the work.

6 Give the engineer a copy of the record of each day’s work on the following workday. Include in the daily records the location and quantity of anchors, grout, rockfall mesh, top support wire rope, hardware, and accessories installed.

219.4.2 Installation

219.4.2.1 General

1 Install the rockfall mesh at the locations designated in the contract or established by the engineer. Install the rockfall mesh to extend down the face to the height specified in the contract; support the rockfall mesh panel at the top with a bearing rope. Support the bearing rope and rockfall mesh with either driven anchors or grouted anchors as specified in the contract. Place mesh so that the natural curl from the roll is toward the face. Do

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not anchor the face or bottom of the mesh. Extend the rockfall mesh above the ditch as specified in the contract.

2 For rockfall mesh with grouted or driven anchors, connect the wire rope to the end grouted anchor as shown in the contract. Secure the ends of the wire rope with wire rope clips placed in configuration and torqued as recommended by the wire rope manufacturer. Overlap the rockfall mesh panel at least 24 in [600 mm] over the bearing rope, secure with locking clips, and hold the rockfall mesh in place by the bearing plates of the grouted anchors, to gain maximum stretching and contouring to the existing surface.

3 Place the rockfall mesh anchors as directed by the engineer. The locations, orientations, lengths, and quantities for the rockfall mesh anchors shown in the contract are approximate. The engineer may increase, reduce, delete, or otherwise alter the anchors as necessary to address actual field conditions.

4 Securely selvage or bound the rockfall mesh joints so that they have a minimum strength equal to that of the body of the mesh. Space fasteners, ties, connectors, locking clips, or hog rings used for fastening edges 12 in [300 mm] apart or less on all sides . Lace the perimeter edges with binding wire by tightly looping through every mesh opening.

5 Ensure all wire rope and threaded bar surfaces are free of sludge, grease, or any other matter, which might inhibit the bonding ability. Exercise special care to prevent damage to the galvanization or epoxy coating during handling and installation. Replace or recoat, according to the manufacturer’s specification and to the satisfaction of the engineer, any threaded bars with damaged epoxy coating.

6 Construct drill holes required for installation of wire rope anchors or grouted anchors, according to the following requirements:

and equipped to inject air into the hole through the drill bit. Ensure the drill hole diameter is compatible with the wire rope or threaded bar and grout to be used.

by the engineer. Do not allow the deviation from those orientations and inclinations to exceed five degrees. Use an angle measuring device to assure the required inclinations. Do not over -drill beyond the final installed position of the anchor by more than 6 in [150 mm].

air introduced at the back of the hole prior to placement of the anchor and grout.

grout cover is provided around the anchor. Place centralizers within 2 ft [0.5 m]

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from the top and bottom of the drill hole. Attach centralizers securely to the anchors so they will not shift during handling or insertion into the drill hole yet will still allow grout tremie pipe insertion to the bottom of the drill hole and allow grout to flow freely up the hole. After the drill hole is cleaned and the anchor is properly placed in the hole, completely fill the hole with cement grout from the bottom of the hole. Promptly remove any excess grout from the soil or rock face.

lengths of the wire rope anchors or grouted anchors to be greater than the minimum length shown in the contract, and lengths may be varied as directed by the engineer. Where the lengths are varied, the use of couplers (or other approved methods as recommended by the manufacturer) may be permitted by the engineer.

219.4.2.2 Grouted Anchors

1 Perform all testing of grouted anchors as specified or as directed by the engineer and as required for the safe prosecution of the work. Perform at least one grout strength test per 10 anchors grouted, or as directed by the engineer . Deliver the grout specimens to the engineer for testing by the department. The engineer will perform tests at three days according to ASTM C1107. The engineer will determine test locations for the grout.

2 Anchor Testing: Testing equipment includes a jack, pump, pressure gauge, and reaction frame. Furnish at least one set of laboratory certified stressing equipment for use in conducting these tests. Ensure each set of testing equipment consists of a suitably sized hydraulic ram, hydraulic pump (hand or electric) with pressure indicator that has 100 psi [690 kPa] interval calibration marks, an extension bar, and associated hardware for testing the anchors . Provide a hydraulic pump that has been calibrated by an independent laboratory while connected to the jack prior to field use. Ensure the stressing ram assembly is recalibrated every 90 days throughout the duration of the project. Keep a calibrated master gauge on site to periodically check the test pressure gauge.

3 Align the jack, bearing plate, and reaction frame with the anchor such that unloading the repositioning of the equipment is not required during the test . Place the stressing equipment over the anchor system in a manner that the jack, bearing plates, and stressing anchorage are axially aligned with (parallel to) the anchor and the anchor is centered within the equipment.

4 Record the required test data as the test proceeds. Do not conduct anchor testing and stressing until the anchor grout has been in place for at least 3 days, or as approved by the engineer. Perform the required testing within 30 days of installation of the element or as approved by the engineer.

5 After an anchor has been accepted by the engineer, the unneeded portion on the anchor may be cut, if not otherwise required for use in re- testing. Cut the anchor according t o the wire rope or bar manufacturer’s recommendations, and as approved by the engineer.

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Take care not to damage the anchor. Do not cut the anchor using a torch or other device which in the opinion of the engineer might affect the strength of the anchorage.

6 Perform a pullout test on a minimum of 10 percent of the grouted anchors for each rockfall mesh system. Pull anchors to the maximum load shown in the contract. If all the tests meet the acceptance criteria (i.e. anchors do not pull out after holding the maximum load for 5 minutes), then no more testing is required. If any anchor pulls out, then test an additional 10 percent of the remaining anchors. If any additional anchors pull out, test an additional 10 percent of the remaining anchors . The engineer will designate pullout test locations. Replace and retest failed anchors at no additional cost to the department.

7 In the event soil materials or pullout testing indicates that the subsurface materials or construction methods are not providing adequate bond for the anchors, the engineer may require additional testing.

219.4.3 Acceptance

1 The engineer will consider pullout tested grouted anchors acceptable when the maximum test load is successfully held for a minimum of 5 minutes with minor jacking of the pump and with minimal distress and deflection of the anchor and testing system.

2 The engineer will consider pullout tested grouted anchors rejected when a pullout failure occurs prior to or at the maximum test load . Pullout failure is defined as the continued pullout movement of the test anchor or loss of pressure on the jacking ram at or below the maximum test load. Record the pullout failure load as part of the test data. Replace all failed anchors at no additional cost to the department, unless otherwise directed by the engineer. If the engineer determines that the test setup is invalid, one attempt may be made to reset the system or propose a modified test system for approval, at no additional cost to the department.

219.5MEASUREMENT and PAYMENT

1 The engineer will measure:

allowance for overlaps. Wire bearing rope, clamps, lacing wire, and locking clips will not be measured separately, but are considered subsidiary to the pay item Rockfall Mesh.

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2 The department will pay as follows:

Pay Item

Pay Unit Measure to the Nearest Pay to the Nearest Driven Anchors EA [Ea] EA [Ea] EA [Ea] Grouted Anchors EA [Ea] EA [Ea] EA [Ea] Rockfall Mesh SY [m2] 0.1 ft [0.05 m] SY [m2]