1、 International Telecommunication Union ITU-T L.88TELECOMMUNICATION STANDARDIZATION SECTOR OF ITU (07/2010) SERIES L: CONSTRUCTION, INSTALLATION AND PROTECTION OF CABLES AND OTHER ELEMENTS OF OUTSIDE PLANT Management of poles carrying overhead telecommunication lines Recommendation ITU-T L.88 Rec. IT
2、U-T L.88 (07/2010) i Recommendation ITU-T L.88 Management of poles carrying overhead telecommunication lines Summary A telecommunication pole is one of the most important network infrastructures used to carry overhead telecommunication lines. In wooden poles, as support of communication lines, the f
3、ollowing circumstances are present: The wood, when the antiseptic efficiency of the preservative treatment has decreased below the threshold, is subjected to the attack of biological agents that cause its destruction. Healthy wood of poles must preserve the mechanical strength that line security req
4、uires. The heavy cost of wooden poles as well as of pole replacement requires conservation to extend the life of the poles, while paying sufficient attention to worker safety and the expected lifetime of the poles. This can be achieved by means of different systems such as reimpregnation, lowering,
5、recover and reclassification. Another material used in common utility poles is concrete. These poles are planted into the ground, but in some cases, they lean or are overturned by forces such as strong wind. This phenomenon is mainly due to a foundation failure. Recommendation ITU-T L.88 deals with
6、integrity testing for telecommunication pole foundation. History Edition Recommendation Approval Study Group 1.0 ITU-T L.88 2010-07-29 15 Keywords Creosote, non-destructive testing (NDT), resonance frequency, telecommunication pole. ii Rec. ITU-T L.88 (07/2010) FOREWORD The International Telecommuni
7、cation Union (ITU) is the United Nations specialized agency in the field of telecommunications, information and communication technologies (ICTs). The ITU Telecommunication Standardization Sector (ITU-T) is a permanent organ of ITU. ITU-T is responsible for studying technical, operating and tariff q
8、uestions and issuing Recommendations on them with a view to standardizing telecommunications on a worldwide basis. The World Telecommunication Standardization Assembly (WTSA), which meets every four years, establishes the topics for study by the ITU-T study groups which, in turn, produce Recommendat
9、ions on these topics. The approval of ITU-T Recommendations is covered by the procedure laid down in WTSA Resolution 1. In some areas of information technology which fall within ITU-Ts purview, the necessary standards are prepared on a collaborative basis with ISO and IEC. NOTE In this Recommendatio
10、n, the expression “Administration“ is used for conciseness to indicate both a telecommunication administration and a recognized operating agency. Compliance with this Recommendation is voluntary. However, the Recommendation may contain certain mandatory provisions (to ensure, e.g., interoperability
11、or applicability) and compliance with the Recommendation is achieved when all of these mandatory provisions are met. The words “shall“ or some other obligatory language such as “must“ and the negative equivalents are used to express requirements. The use of such words does not suggest that complianc
12、e with the Recommendation is required of any party. INTELLECTUAL PROPERTY RIGHTS ITU draws attention to the possibility that the practice or implementation of this Recommendation may involve the use of a claimed Intellectual Property Right. ITU takes no position concerning the evidence, validity or
13、applicability of claimed Intellectual Property Rights, whether asserted by ITU members or others outside of the Recommendation development process. As of the date of approval of this Recommendation, ITU had not received notice of intellectual property, protected by patents, which may be required to
14、implement this Recommendation. However, implementers are cautioned that this may not represent the latest information and are therefore strongly urged to consult the TSB patent database at http:/www.itu.int/ITU-T/ipr/. ITU 2011 All rights reserved. No part of this publication may be reproduced, by a
15、ny means whatsoever, without the prior written permission of ITU. Rec. ITU-T L.88 (07/2010) iii CONTENTS Page 1 Scope 1 2 References. 1 3 Definitions 1 3.1 Terms defined in this Recommendation . 1 4 Abbreviations and acronyms 1 5 Conventions 1 6 Management of poles carrying overhead telecommunicatio
16、n lines . 2 6.1 Overview of wooden poles management . 2 6.2 Wooden poles inspection 2 6.3 Integrity testing for concrete telecommunication pole foundation . 5 Appendix I The Spanish experience with poles management 7 I.1 Poles used for telecommunications in Spain 7 I.2 Agents and circumstances of bi
17、ological destructions . 7 I.3 Aspect of attacked wood 8 Appendix II The Korean experience for identifying concrete poles foundation 10 II.1 Testing program 10 II.2 The first peak resonance frequencies . 10 II.3 Discussions . 11 Bibliography. 12 Rec. ITU-T L.88 (07/2010) 1 Recommendation ITU-T L.88 M
18、anagement of poles carrying overhead telecommunication lines 1 Scope This Recommendation: describes how to measure the magnitude of attacks in poles; describes how to unearth a pole; describes integrity testing to identify the base condition of telecommunication poles; describes integrity testing wh
19、ich includes a non-destructive testing method; describes integrity testing for precast concrete poles that are planted into the ground. 2 References None. 3 Definitions 3.1 Terms defined in this Recommendation This Recommendation defines the following terms: 3.1.1 concrete: An artificial, stonelike
20、material used for various structural purposes, made by mixing cement and various aggregates, as sand, pebbles, gravel, or shale, with water and allowing the mixture to harden. 3.1.2 creosote: Wood creosote is a colourless to yellowish greasy liquid with a smoky odour and burned taste. Wood creosote
21、is used as a wood preservative and has also been used as a disinfectant, a laxative, and a cough treatment. 3.1.3 non-destructive testing (NDT): This method detects defects such as cracking and corrosion, not destroying the test object. There are different methods of testing available, such as the u
22、ltrasonic pulse velocity method and the stress wave propagation method. 3.1.4 resonance frequency: Resonance is the tendency of a system to oscillate at maximum amplitude at certain frequencies. When damping is small, the resonance frequency is approximately equal to the natural frequency of the sys
23、tem, which is the frequency of free vibrations. 3.1.5 unearthing: Action of digging out the earth. 4 Abbreviations and acronyms This Recommendation uses the following abbreviation: NDT Non-Destructive Testing 5 Conventions None. 2 Rec. ITU-T L.88 (07/2010) 6 Management of poles carrying overhead tel
24、ecommunication lines 6.1 Overview of wooden poles management Creosoted poles must be inspected periodically and, depending on their state, they may continue in service or be replaced. In order to prolong pole lifetime, it is advisable, provided that the authorized products exist, to treat them or re
25、impregnate them. It is recommended that the inspection and reimpregnation activities be carried out simultaneously because, amongst other reasons, the area most prone to attacks is under and just above earth. In order to make a good inspection by traditional methods, it is necessary to unearth the p
26、ole and, because once unearthed, the aeration of the land increases the danger of attack by microorganisms. As a result, it is also necessary to reimpregnate that area to counteract the aforementioned danger. Because of the fact that it is not advisable to use reimpregnating products on a large scal
27、e, inspections should be done without unearthing the poles and only in those cases where the previous examination brings up doubts about the state of the pole; the pole should be unearthed in order to inspect the buried part. Whenever a pole is unearthed, it should be treated with a phytosanitary tr
28、eatment, or any other authorized product. The maximum period between inspections should be 5 years. The dry season is the most favourable season of the year for inspection works; consequently, climatological regional conditions should be taken into account before setting the inspection dates. 6.2 Wo
29、oden poles inspection The antiseptic power of creosote must be guaranteed by the creosoted pole supplier for 10 years; for this reason, poles must be inspected before this period expires and, depending on their state, would continue in service or be replaced. As previously stated, the most suitable
30、season for inspection works is the dry season. Before proceeding with an inspection work on a pole, the land around it must be cleaned, and afterwards 2 or 3 cm around it can be scratched. The inspection data will be written down and collected. It is mandatory to inspect a pole before climbing it Th
31、e poles in bad state should be marked with a red disc of a diameter of 10 cm, whose meaning is: “DANGER; DO NOT CLIMB“. These poles must be dismantled as soon as possible. Apart from periodical inspections, the lines that are the object of big refurbishments, such as changes in emplacement, should b
32、e inspected. The operations to be done in a pole inspection will be detailed below: 6.2.1 Materials To unearth the pole, apart from the properly established tools, it has been shown that the most useful tools to use are a pickaxe and a hoe, or a tool that combines both. The necessary materials to in
33、spect a pole are the following: 1.5 kg hammer. 20 cm drill probe. Tape measure. Rec. ITU-T L.88 (07/2010) 3 Tool to scrape the poles surface such as a chisel. Depth slide gauge. Thickness slide gauge. 6.2.2 Visual inspection Before proceeding with the inspection, an initial evaluation of the resista
34、nce of the pole as well as of its embedment should be carried out. For this purpose, the pole should be repeatedly pushed hard with the hand. The visual inspection of the pole should be done thoroughly over its entire surface, from the base to the head, to detect the presence of any of the following
35、 defects: Bird attack. Small holes (made by insects) of 1 to 2 mm in diameter. Presence of knots. Stretch or fracture of fibres. Fungus or insect attack. Examination for possible deficiencies related with the line, such as braces, installed elements, etc., should be undertaken in order to put forwar
36、d the appropriate conservation works. 6.2.3 Inspection by percussion The pole should be hit using the appropriate hammer. Depending on the impact and the sound produced, the state of the pole can be determined. A “healthy“ pole, with a good density of wood, produces a hard impact with some rebound,
37、and a clear and vibrating sound. An “attacked“ pole with cavities, and differences in wood density, produces a muffled and muted sound. However, the different tonalities produced due to the nature of the land, the embedment of the pole, the installed elements and the climatological conditions should
38、 also be taken into account. The appreciation of the different tonalities is acquired through the adequate preparation and/or practise. The exploration with a hammer should be done from the base (earth line if the pole is not unearthed) to the height reached by the arm. In special cases, the examina
39、tion can be extended to higher areas, by climbing with the assistance of climbing irons and assuring beforehand the solidity of the pole. 6.2.4 Attack measurement Once the affected zone is detected, the magnitude of the attack is determined by means of direct measurement in the case of external atta
40、cks and by drill probe in internal attacks, with the help of the appropriate gauges. When the examination of the pole is complete, the holes made with the drill must be sealed with wooden pegs of creosoted wood of 60 mm length and 15 mm of diameter, with a pointed tip of 10 mm. 4 Rec. ITU-T L.88 (07
41、/2010) 6.2.4.1 Operating with the drill probe To determine the inside state of the pole, a drill probe should be used. Operating with it is easy: Once drilled to the desired depth, an extracting “spoon“ is introduced in the drills rod, sliding it between the inside surface of it and the wooden contr
42、ol. Turning it completely anticlockwise causes the extracting “spoon“ to be extracted with the wooden control inside it. Figure 1 Operation with the drill probe Sounding should always be done in the radial direction; the depth should be determined by the measurement and should be repeated for the be
43、st quantification of the attack. Before introducing the drill probe, it should be checked that, at the selected point, there are not any nails or knots or any other obstacles that could damage the tool. 6.2.4.2 Operating with the gauges The gauges are steel rod wire punches graduated in centimetres.
44、 The depth gauge, operated as a punch, helps to determine the depth of an external cavity, or an internal cavity made accessible by the drill probe. The wood at the bottom must always be tested down to healthy fibres, keeping the cut of the gauge horizontal to the ground, since the wooden fibres are
45、 longitudinally vertical. The thickness gauge, with its tip bent at an angle of 90 degrees, is designed to measure the thickness of healthy wood in an internal cavity and also the thickness of healthy wood in a visible cavity. In the first case, the gauge is introduced in the hole left by the drill
46、probe, and, in the second, it is directly applied to the edge of the cavity using the sharp right angled edge of the gauge. 6.2.5 Wood pole unearthing If, when the previous operations have been carried out on the pole without unearthing, there is still some doubt about the state of the pole, it shou
47、ld be unearthed and the unearthed area inspected. The pole unearthing consists of digging, using the appropriate tools, a hole of 50 cm deep and 35 cm radius around the pole. With the pole unearthed, prior to inspection, the earth adhering to the surface of the unearthed area should be removed, and
48、in the case where the pole has any paper or plastic band adhering from a previous treatment, it should be removed and eliminated according to the current legislation. Then the inspection should be conducted following all the steps indicated in the preceding clauses (visual, percussion, external atta
49、cks and internal). Rec. ITU-T L.88 (07/2010) 5 Once the inspection is complete, the unearthed area should be protected as well as the area immediately above the soil line, such protection shall be conducted with approved products and systems. Subsequently, the pit must be filled and compacted. 6.3 Integrity testing for concrete telecommunication pole foundation 6.3.1 Conventional methods 6.3.1.1 Visual inspection This method consists of detecting tension cracks or bulging parts of the ground in which the pole is planted (see Figure 2). Mea
