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1、 Reference number ISO 16134:2006(E) INTERNATIONAL STANDARD ISO 16134 First edition 2006-02-01 Earthquake- and subsidence-resistant design of ductile iron pipelines Conception de canalisations en fonte ductile rsistant aux tremblements de terre et aux affaissements ii iii Contents Page Foreword iv In
2、troduction v 1 Scope . 1 2 Terms and definitions. 1 3 Earthquake-resistant design . 1 3.1 Seismic hazards to buried pipelines. 1 3.2 Qualitative design considerations 2 3.3 Design procedure . 2 3.4 Earthquake resistance calculations and safety checking 3 3.5 Calculation of earthquake resistance Resp
3、onse displacement method 3 4 Design for ground deformation by earthquake . 6 4.1 General. 6 4.2 Evaluation of possibility of liquefaction. 6 4.3 Checking basic resistance. 7 5 Design for ground subsidence in soft ground (e.g. reclaimed ground) . 7 5.1 Calculating ground subsidence 7 5.2 Basic safety
4、 checking 7 6 Pipeline system design 8 6.1 Pipeline components 8 6.2 Earthquake-resistant joints . 8 Annex A (informative) Example of earthquake resistance calculation. 9 Annex B (informative) Relationship between seismic intensity scales and ground surface acceleration. 17 Annex C (informative) Exa
5、mple of calculation of liquefaction resistance coefficient value 18 Annex D (informative) Checking pipeline resistance to ground deformation 23 Annex E (informative) Example of ground subsidence calculation 26 Bibliography. 32 iv Foreword ISO (the International Organization for Standardization) is a
6、 worldwide federation of national standards bodies (ISO member bodies). The work of preparing International Standards is normally carried out through ISO technical committees. Each member body interested in a subject for which a technical committee has been established has the right to be represente
7、d on that committee. International organizations, governmental and non-governmental, in liaison with ISO, also take part in the work. ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of electrotechnical standardization. International Standards are draf
8、ted in accordance with the rules given in the ISO/IEC Directives, Part 2. The main task of technical committees is to prepare International Standards. Draft International Standards adopted by the technical committees are circulated to the member bodies for voting. Publication as an International Sta
9、ndard requires approval by at least 75 % of the member bodies casting a vote. Attention is drawn to the possibility that some of the elements of this document may be the subject of patent rights. ISO shall not be held responsible for identifying any or all such patent rights. ISO 16134 was prepared
10、by Technical Committee ISO/TC 5, Ferrous metal pipes and metallic fittings, Subcommittee SC 2, Cast iron pipes, fittings and their joints. v Introduction Buried pipelines are often subjected to damage by earthquakes. It is therefore necessary to take earthquake resistance into consideration, where a
11、pplicable, in the design of the pipelines. In reclaimed ground and other areas where ground subsidence is expected, the pipeline design must also take the subsidence into consideration. Even though ductile iron pipelines are generally considered to be earthquake-resistant, since their joints are fle
12、xible and expand/contract according to the seismic motion to minimize the stress on the pipe body, nevertheless there have been reports of the joints becoming disconnected by either a large quake motion or major ground deformation such as liquefaction. blank 1 Earthquake- and subsidence-resistant de
13、sign of ductile iron pipelines 1 Scope This International Standard specifies the design of earthquake- and subsidence-resistant ductile iron pipelines suitable for use in areas where seismic activity and land subsidence can be expected. It provides a means of determining and checking the resistance
14、of buried pipelines and also gives example calculations. It is applicable to ductile iron pipes and fittings with joints that have expansion/contraction and deflection capabilities, used in pipelines buried underground. 2 Terms and definitions For the purposes of this document, the following terms a
15、nd definitions apply. 2.1 burying placing of pipes underground in a condition where they touch the soil directly 2.2 response displacement method earthquake-resistant calculation method in which the underground pipeline structure is affected by the ground displacement in its axial direction during a
16、n earthquake 2.3 liquefaction phenomenon in which sandy ground rapidly loses its strength and rigidity due to repeated stress during an earthquake, and where the whole ground behaves just like a liquid 2.4 earthquake-resistant joint joint having slip-out resistance as well as expansion/contraction a
17、nd deflection capabilities 3 Earthquake-resistant design 3.1 Seismic hazards to buried pipelines In general, there are several main causes of seismic hazards to buried pipelines: a) ground displacement and ground strain caused by seismic ground shaking; b) ground deformation such as a ground surface
18、 crack, ground subsidence and lateral spread induced by liquefaction; c) relative displacement at the connecting part with the structure, etc.; d) ground displacement and rupture along a fault zone. Since ductile iron pipe has high tensile strength as well as the capacity for expansion/contraction a
19、nd deflection from its joint part, giving it the ability to follow the ground movement during the earthquake, the 2 stress generated on the pipe body is relatively small. Few ruptures of pipe body have occurred during earthquakes in the past. It is therefore important to consider whether the pipelin
20、e can follow the ground displacement and ground strain without slipping out of joint when considering its earthquake resistance. The internal hydrodynamic surge pressures induced by seismic shaking are normally small enough not to be considered. 3.2 Qualitative design considerations 3.2.1 General To
21、 increase the resistance of ductile iron pipelines to seismic hazards, the following qualitative design measures should be taken into consideration. a) Provide pipelines with expansion/contraction and deflection capability. EXAMPLE Use of shorter pipe segments, special joints or sleeves and anti-sli
22、p-out mechanisms according to the anticipated intensity or nature of the earthquake. b) Lay pipelines in a firm foundation. c) Use smooth back fill materials. NOTE Polyethylene sleeves and special coating are also effective in special cases. d) Install more valves. 3.2.2 Where high earthquake resist
23、ance is needed It is desirable to enhance the earthquake resistance of parts connecting the pipelines to structures and when burying the pipes in a) soft ground such as alluvium, b) reclaimed ground, c) filled ground, d) suddenly changing soil types (geology) or topography, e) sloping ground, f) nea
24、r revetments, g) liquefied ground, and/or h) near an active fault. 3.3 Design procedure To ensure earthquake-resistant design for ductile iron pipelines: a) select the piping route; b) investigate the potential for earthquakes and ground movement; c) assume probable earthquake motion (seismic intens
25、ity); d) undertake earthquake-resistant calculation and safety checking; e) select joints. Solid/firm foundations should be chosen for the pipeline route. When investigating earthquakes and ground conditions, take into account any previous earthquakes in the area where the pipeline is to be laid. 3
26、3.4 Earthquake resistance calculations and safety checking When checking the resistance of pipelines to the effects of earthquakes, the calculation shall be carried out for the condition in which the normal load (dead load and normal live load) is combined with the influence of the earthquake. The p
27、ipe body stress, expansion/contraction value of joint, and deflection angle of joint are calculated by the response displacement method. Earthquake resistance is checked by comparing these values with their respective allowable values. The basic criteria are given in Table 1. A flowchart of earthqua
28、ke resistance determination and safety checking is shown in Figure 1. The basic equations only for earthquake resistance calculation are given in 3.5. A detailed example of calculation is given in Annex A. Table 1 Basic earthquake resistance check criteria Load condition Criterion Pipe body stress u
29、 Allowable stress (proof stress) of ductile iron pipe Expansion/contraction value of joint u Allowable expansion/contraction value of ductile iron pipe joint Load in earthquake motion and normal load Deflection angle of joint u Allowable deflection angle of ductile iron pipe joint 3.5 Calculation of
30、 earthquake resistance Response displacement method 3.5.1 General This method shall be used except when the manufacturer and the customer agree on an alternative recognized method. 3.5.2 Design earthquake motion The design acceleration for different seismic intensity scales can be determined accordi
31、ng to the relationship between the several kinds of seismic intensity scales and the acceleration of ground surface, as given in Annex B. 3.5.3 Horizontal displacement amplitude of ground The horizontal displacement amplitude of the ground is calculated using Equation (1) (see Annex A): ( ) 2 G h co
32、s 22 Tx Uxa H = (1) where ( ) h Ux is the horizontal displacement amplitude of the ground x m deep from the ground surface to the centre line of the pipe, in metres (m); x is the depth from the ground surface, in metres (m); TG is the predominant period of the subsurface layer, in seconds (s); a is
33、the acceleration on the ground surface for design, in metres per second squared (m/s2); H is the thickness of the subsurface layer, in metres (m). 4 Figure 1 Flowchart for calculation of earthquake resistance of buried pipelines 5 3.5.4 Pipe body stress Pipe body stress is calculated using Equations
34、 (2), (3) and (4). Axial stress: ( ) h L11 Ux E L = (2) Bending stress: ( ) 2 h B22 2 2D Ux E L = (3) Combined stress: 22 LB 3,12 x =+ (4) where L , B are the axial stress and the bending stress, respectively, in pascals (Pa); x is the combination of the axial and bending stresses, in pascals (Pa);
35、1 is the correction factor of axial stress in the case of expansion flexible joints; 2 is the correction factor of the bending stress in the case of expansion flexible joints; 1 , 2 are the transfer coefficient of ground displacement in the pipe axis and pipe perpendicular directions, respectively;
36、( ) h Ux is the horizontal displacement amplitude of ground x m deep from the ground surface, in metres (m); L is the wavelength, in metres (m); D is the outside diameter of the buried pipeline, in metres (m); E is the elastic modulus of the buried pipeline, in pascals (Pa). 3.5.5 Expansion/contract
37、ion of joint in pipe axis direction The amount of expansion/contraction of the joint in the pipe axis direction is calculated using Equation (5) (see Annex A): G ul= (5) where u is the amount of expansion/contraction of the joint in the pipe axis direction, in metres (m); G is the ground strain U L
38、= h L is the wavelength, in metres (m); Uh is the horizontal displacement amplitude of ground x m deep from the ground surface, in metres (m); l is the pipe length, in metres (m). 6 3.5.6 Joint deflection angle The joint deflection angle is calculated using Equation (6) (see Annex A): 2 h 2 4l U L =
39、 (6) where is the joint deflection angle, in radians (rad); l is the pipe length, in metres (m); Uh is the horizontal displacement amplitude of ground x m deep from the ground surface, in metres (m); L is the wavelength, in metres (m). The above calculations, such as the amount of expansion/contract
40、ion of joint by the response displacement method, are based on the assumption that the ground will deform uniformly. However, since strain can be concentrated locally during an earthquake (due to the heterogeneity of the ground) and there is a possibility that the value can be greater than the calcu
41、lation result, a certain value of safety margin for instance, twice as much is recommended. 4 Design for ground deformation by earthquake 4.1 General Large-scale ground deformation such as ground cracks, ground subsidence and lateral displacement near revetments and inclined ground can be generated
42、by liquefaction during an earthquake. Since such ground deformations can affect the buried pipeline, it is necessary to consider this possibility and to take it into account in the pipeline design. 4.2 Evaluation of possibility of liquefaction The possibility of liquefaction shall be evaluated for s
43、oil layers when the following conditions are present: a) saturated soil layer u 25 m from the ground surface; b) average grain diameter, D50, u 10 mm; c) content by weight of small grain particles (with grain diameter u 0,075 mm) u 30 %. The possibility of liquefaction can be evaluated by calculatin
44、g the liquefaction resistance coefficient, FL, using Equation (7): L FR L= (7) where R is the dynamic shear strength ratio indicating the resistance to liquefaction; L is the ground shear stress ratio during an earthquake, which indicates the generated shear stress in ground due to the earthquake. W
45、hen FL then the pipeline can absorb the ground displacement and has been safely designed for ground deformation in its axis direction. D.3 Example in pipe perpendicular direction D.3.1 Specifications and conditions The example pipeline and the conditions acting upon it are as follows. a) Joint: eart
46、hquake-resistant joint b) Maximum deflection angle at joint: = 7 c) Number of joints: n = 12 d) Pipe length: l = 6 m e) Assumed ground displacement in pipe perpendicular direction: r = 3 m D.3.2 Result of checking D.3.2.1 Maximum amount of displacement in the pipe perpendicular direction, Hmax This
47、is calculated using Equation (D.2): () max tantan2tan3tan2tanHl= +()6,0tan7tan14tan21tan14tan7=+ = 7,0 m (D.3) where l is the pipe length = 6,0 m; is the maximum deflection angle at joint = 7; 25 Dimensions in metres Figure D.1 Maximum amount of displacement D.3.2.2 Result of safety checking When ma
48、x H exceeds () rmaxr ,H then the pipeline can absorb the ground displacement and has been safely designed for the ground deformation in its perpendicular direction. 26 Annex E (informative) Example of ground subsidence calculation E.1 General This annex presents an example of the calculation of grou
49、nd subsidence, using Equation (9). The end result varies depending on the number of layers chosen for the calculation and could be an under-estimation of the degree of subsidence. Where any doubt exists, a fully integrated solution should be carried out. E.2 Specifications and conditions The example pipeline and conditions are the following. a) Kind of pipe: Ductile iron pipe, nominal diameter 1 000 mm (K-9 class pipe) a) Outside diameter of pipe: D = 1,048 m b) Standard thickne