Section 263 — Draped Rockfall Protection

Description

263.01This work consists of installing draped rockfall protection.

Material

263.02Conform to the following Subsections: Anchorage devices 722.01 Draped rockfall protection fabric 710.09 Hollow- core self -drilling anchors 722.07(a) Non-shrink grout 701.04(b)(2) Rockfall protection hardware 717.01(f) Water for cementitious materials 725.01(a) Wire rope 709.03 Wire rope anchors 722.07(b)

Construction Requirements

263.03Qualifications. At least 30 days before starting rockfall protection work , submit the following for approval:

(a)On-site supervisor. A résumé describing experience on at least five projects installing draped rockfall protection systems on steep slopes within the past 5 years. Include project names, locations, and contact information for project owners;

(b)Drill operators. A résumé describing experience installing at least 1000 linear fe et of ground anchors on steep slopes within the past 3 years. Include project names, locations, and contact information for project owners ;

(c)Rope supported laborers. A résumé for rope supported laborers conforming to Subsection 262.02; and

(d)Draped rockfall protection fabric material supplier. Include the following:

(1)Documentation showing the manufacturer has at least 5 years ’ experience manufacturing the specified products used in similar system applications and capacities. Include details of the manufacturer’s testing procedures and certification of a QA program; and

(2)Include summaries of at least 5 past projects with similar site conditions where draped rockfall protection systems were installed using the supplier’s c able nets and steel fabric material , as applicable . Include owner names and contact information.

263.04Submittals . At least 30 days before starting draped rockfall protection work, submit the following according to Subsection 104.06:

(a)Design. Submit the proposed draped rockfall protection design and calculations.

(b)Materials. Do not order material until the applicable material submittals are approved.

(1)An inclusive list with technical data sheets for each proposed system component including draped rockfall protection fabric, grout, tendon anchors, wire ropes, wire rope anchors, thimbles, ferrules, and other fastening hardware.

(2)Drawings for temporary yokes or load frames used for anchor proo f testing including load cells, test jack and master gauges, and calibration data performed by an independent testing laboratory within 90 days of the submittal for each device used. Recalibrate each device used every 90 days from the originally submitted calibration date.

(c)Equipment.

(1)List of equipment to be used for rockfall protection work, including equipment capacities, intended uses, and rental rates.

(2)Provide calibration data, including a graph of torque versus tension for each torque wrench to be used. Include certifications showing calibration testing was conducted by an independent laboratory within 90 days of the date submitted.

(d)Work plan. Include the following in the work plan:

(1)Explain the safety procedures on how personnel and equipment will perform work so that the public, construction personnel, and equipment exposures to hazardous and potentially hazardous conditions are minimized. Include temporary rockfall mitigation measures, special designs, and installation procedures deemed necessary to saf ely perform the rockfall protection work;

(2)A list of materials, devices, and equipment used, and the methods that will be incorporated to protect existing underground and above -ground facilities, and minimize impacts to the environment;

(3)Description of how personnel and equipment will install draped rockfall protection fabric materials on the project slope locations, including temporary anchoring needed;

(4)A list of materials, equipment, and the methods for drilling, installing, grouting, and testing ground anchors; including the mix design for grouting operations; and

(5)Procedure for attaching draped rockfall protection fabric materials to upper support ropes, adjacent draped rockfall protection fabric panels, and other temporary and permanent supports. Include m ethods and equipment for delivering and placing on the designed slope locations.

263.05General. Perform safety scaling that the Contractor deems necessary according to Section 262. Before installing draped rockfall protection , complete work required according to Sections 260, 262, and 267, and other on-slope rock stabilization work as applicable. If applicable, treat exposed steel surfaces according to Section 563. Verify the draped rockfall protection work limits. Perform required scaling, rock bolting and doweling, unlined and lined drain holes in rock, and other on -slope rock stabilization work before connecting the draped rockfall protection fabric to the ground anchors and support ropes. Store, handle, and install draped rockfall protection without damaging the rockfall protection system, colored finish, or galvanized finish. Repair galvanized finishes according to Section 563. Replace damaged portions of the rockfall protection system. Construct the draped rockfall protection system using panels comprised of double -twist wire mesh, high tensile strength wire mesh, or cable net with wire mesh backing as specified in the plans. Install the draped rockfall protection from the top working downward, contouring the draped rockfall protection fabric material with the existing ground topography to the bottom limits of the required installation, without creating loose draped rockfall protection fabric pockets that trap falling rocks. Trim draped rockfall protection fabric material as ne eded and treat field cuts according to Section 563.

263.06Upper Support Ground Anchors. Permanently mark proposed anchor locations as approved. Install anchors only at approved locations. Install ground anchors by centering the anchors plumb or normal to the existing slope at least 2 inches off the bottom of the hole and according to the following field conditions as applicable.

(a)Type I soil installation. Excavate a minimum 5.5-foot deep, 12- inch diameter hole to receive th e anchor. Install galvanized wire rope with the anchor end possessing a factory installed ferrule that has a minimum tensile strength equal to that of the wire rope used. Completely fill anchor holes with minor concrete, to encapsulate anchors within holes. Construct minor concrete according to Section 601.

(b)Type II soil installation. Use sacrificial drill bits to install hollow -core self -drilling anchors with a minimum diameter of 1¼ inches to a minimum depth of 5.5 feet, attached to ¾ -inch diameter galvanized wire ropes with factory installed couplers that possess a minimum tensile strength equal to that of the wire ropes used. Completely fill drilled holes with non -shrink grout, to encapsulate anchors within drilled holes.

(c)Rock installation. Excavate a minimum 5.5 -foot deep, 2- inch diameter hole to receive the anchor. Install the ferrule -end wire rope specified under Subsection 263.06(a) . Use non- shrink grout to fill anchor holes according to Subsection 263.06(b) . After filling anchor holes with non- shrink grout or concrete, allow cementitious material to cure, and do not disturb or apply loads to anchors for at least 3 days.

263.07Testing Ground Anchors. Perform axial pullout proof tests on 5 percent of the installed upper support ground anchors, with at least three tests performed. Complete testing before connecting system components to anchors. Perform the test by applying a 20- kip test load to the anchor for 10 minutes, using a temporary yoke or load frame that does not apply bearing pressures on the ground within 3 feet of the anchor. Proof tests for an anchor will be accepted when the anchor maintains the test load for 10 minutes with no loss of load. Replace anchors that do not pass axial pullout proof testing at no additional cost to the Government. 263.08 Wire Ropes and Draped Rockfall Protection Fabrics. Install ground anchors by centering the anchors plumb or normal to the existing slope at least 2 inches off the bottom of the hole and according to the following field conditions as applicable. Attach tag lines to upper support ground anchors only after the required proof testing under Subsection 263.07 has been completed. Set wire rope lengths in the field, terminating each wire rope run with a loop end. Attach support ropes to tag lines with the required shackles. Attach draped rockfall protection fabrics to support rop es, and the upper 12 feet of adjacent fabric panels by lacing wire rope through each draped rockfall protection fabric and panel cell and around adjacent support and seaming ropes. Use ¼ -inch diameter wire rope for lacing on draped rockfall protection sys tems consisting of double -twist wire mesh and high tensile strength wire mesh, and 5/16-inch diameter wire rope for draped rockfall protection systems consisting of cable nets with wire mesh backing. On draped rockfall protection systems consisting of doub le-twist wire mesh, overlap adjacent draped rockfall protection fabric panels at least 3 inches. On draped rockfall protection systems consisting of high tensile strength wire mesh or cable net with wire mesh backing, connect adjacent draped rockfall protection fabric panels according to the manufacturer’s recommendations at horizontal and vertical seams. Increase overlaps as needed to cover the work limits and minimize field cuts. Lace additional wire ropes through draped rockfall protection fabric cells to join overlapping draped rockfall protection fabrics overlapping greater than 3 inches. Do not use hog ring fasteners to join overlapping draped rockfall protection fabrics consisting of cable nets with wire mesh backing panels. Set the bottoms of draped rockfall protection fabric panels, between 3 and 8 feet above the ditch line, and attach fabric bottoms to the existing slope according to the manufacturer’s recommendations.

263.09Acceptance. See Table 263-1 for sampling, tes ting, and acceptance requirements. Material for draped rockfall protection will be evaluated under Subsections 106.02, 106.03, and 106.04. Submit a production certificate for wire ropes and tendon anchors. Construction of draped rockfall protection will be evaluated under Subsections 106.02 and 106.04. Drain holes in rock will be evaluated under Section 267. Minor concrete will be evaluated under Section 601. Rock bolts and dowels will be evaluated under Section 260. Safety scaling will be evaluated under Section 262. Treating exposed steel surfaces, treating galvanized steel field cuts, and repairing damaged galvanizing will be evaluated under Section 563.

Measurement

263.10Measure the Section 263 pay items listed in the bid schedule according to Subsection 109.02 and the following as applicable: When measuring draped rockfall protection by the square yard, measure the completed in place work performed on the ground surface, excluding overlaps and areas trimmed off.

Payment

263.11The accepted quantities will be p aid at the contract price per unit of measurement for the Section 263 pay items listed in the bid schedule. Payment will be full compensation for the work prescribed in this Section. See Subsection 109.05 . Table 263-1 Sampling, Testing, and Acceptance Requirements

Material or

Product

(Subsection) Type of

Acceptance

(Subsection) Characteristic Category Test Methods

Specifications Sampling

Frequency Point of

Sampling Split

Sample Reporting

Time Remarks

Production

Non-shrink

grout (701.04(b)(2) ) Measured & tested for conformance (106.04 ) Flow – ASTM C939 1 per mix design

Source of

material Yes, if requested Within 24 hours after completion of test –

Compressive

strength (3 -day and 7- day) – ASTM C109 1 set from each batch of grout Source of material Yes, if requested Within 24 hours after completion of test –

Proof test for

draped rockfall protection anchors Measured & tested for conformance (106.04 ) Deformation – Subsection

263.075% of installed anchors but not less than 3 Installation No Within 24 hours after completion of test – Note: Collect samples from the end of the grout line at the point of applications .