SANS 10120-5 LG-1983 Code of practice for use with standardized specifications for civil engineering construction and contract documents Part 5 Contract administration Section LG P.pdf

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1、 Collection of SANS standards in electronic format (PDF) 1. Copyright This standard is available to staff members of companies that have subscribed to the complete collection of SANS standards in accordance with a formal copyright agreement. This document may reside on a CENTRAL FILE SERVER or INTRA

2、NET SYSTEM only. Unless specific permission has been granted, this document MAY NOT be sent or given to staff members from other companies or organizations. Doing so would constitute a VIOLATION of SABS copyright rules. 2. Indemnity The South African Bureau of Standards accepts no liability for any

3、damage whatsoever than may result from the use of this material or the information contain therein, irrespective of the cause and quantum thereof. SABS 0110 : Part 5 Section X-1983 Pipe jacking PART 5 : CONTRACT ADMINISTRATION SECTION LG CONTENTS Clause Page Number START OF CONSTRUCTION 1 General .

4、1 . IMMEDIATELY AFTER THE HANDING OVER OF THE SITE 1 Liaison with Third Parties 1 . nsuring the Practicabilty of Jacking 1 Tolerances . 1 DURING CONSTRUCTION 1 Methods of Construction 1 Lead pipe and overbreak 1 . Sealing of pipes 1 Joints at intermediate jacking stations 1 Jacking 1 De-watering 1 .

5、 Excavation of the face 2 Checking line and level 2 Settlements . 2 Steps to reduce jacking forces 2 Pipe to be kept moving during jacking 2 provision for lubrication 2 Earth resistance to jacking loads 2 Maintaining alignment 2 Supervision 2 Tolerances . 2 . Administration 2 . Special equipment for

6、 pipe jacking 2 Thrust pit length 2 Pipes to be of adequate strength Precautions when jacking under or near buildings . Intermediate jacking stations Blasting Occupation details for an alternative “cut and cover“ const QUALITY CONTROL AND OTHER CONSIDERATIONS . Quality Control Disputes . ruct June 1

7、983 Approved by the COUNCIL OF THE SOUTll AFRICAN BUREAU OF STANDARDS SABS 0120 : Part 5 Section LG-1983 Pipe jacking SABS 1200 LG : PIPE JACKING NOTE: The clause numher(s) given at the beginning or after the heading of a clause is/are, unless otherwise stated, the numnber(s) of the relevant clause(

8、s) of SABS 1200 LG. START OF CONSTRUCTION GENERAL. For the purposes of this part of the code contract administration starts with instructions to the contractor to commence work as set out in Subclause 4.1 of Section 0. IMMEDIATELY AFTER THE HANDING OVER OF TTIE SITE LIAISON WITH THIRD PAR+IES. In th

9、e case of work on the property of the South African Transport Services, the attention of the contractor should be drawn to the requirements of Clause 6 of the south African Transport Services Specification E7 covering works on, over, under or adjacent to railway lines. In the case of work on the pro

10、perty of any other third party, the contractor should be advised of the particular requirements that must be complied with. The engineer should ensure that all the necessary arrangements have been lilde with the third party. ENSURING THE PRACTICABILITY OF JACKING. The contractor should take all nece

11、ssary steps to ensure that pipes of the internal diameters called for in the schedule can be jacked over the full distances re- quired. If he concludes that because of the actual conditions on site or for any other reason, jacking of thc proposed plpes is impractical, he should ask the engineer for

12、other instructions. Where he had, in his tender, offered pipe jacking as an alternative method of construction, and he now finds that additional solls investigation is necessary, he must bear the cost of such lnvestigatlon as lt should have been allowed for in his tender (see also 3.2.5 below). TCLE

13、RANCES (Subclause 6.2). Where the tolerances given in Subclause 6.2 of SABS 1200 LG are not to apply, the tolerances should be agreed upon between the cngmeer and the contractor before work commences. DURING CONSTRUCTION METIIODS OF CONSTRUCTION 1,ead Pipe and Overbreak (Subclause 2.3). A lead plpe

14、with a rebated front end over which the trailing end of the shield 1s frtted should be the first concrete pipe used. Because there rs no substantial difference between the outside diameter of the shleld and of the pipeline, this should ensure that overbreak is kept to a minimum. Sealing of Pipes (Su

15、bclause 3.1). Joints between pipes may be sealed by the use of modified ogee type ends with a rubber ring confined within the joint, or by other suitable methods. Joints at Intermediate Jacking Stations. The joint between each pair of pipes at an intermediate jacking station should be so designed th

16、at a substantial and permanent caulked seal may be constructed within the joint with the use of an approved material that will withstand a back pressure of up to 200 kPa (20 m head of water). Jacking. The directionally adjustable shleld should be used to keep the head of the lead pipe in alignment.

17、The shield should be continuously checked for level and line and so adjusted as to minimize deviations. Ilard but resilient thrust plates (see Subclause 4.2 of SABS 1200 1.G) should be inserted between the abutting ends of the pipes to transfer the jacking force. Each thrust plate should be in the f

18、orm of a completc circle and of sufficient width to cover the end of each pipe completely. Ik-watering. De-watering of the ground through which the pipes are to be jacked, by well-pointing or other means, is essential if the watertable is above or near to invert level or if the soil is unstable when

19、 inundated. The following two reports illustrate the significance of this requirement: a) Contract XYZ Crossing No. 2 : 490 mm sewer in 1 500 mm ID sleeve: A collapse of the sand embankment into the lead pipe occurred on this job as a result of unsatisfactory de-watering (owing largely to casualness

20、 and inefficiency) during jacking. The resulting sinkhole between the railway tracks was backfilled from the surface. .1n addition, the finished position of the sleeve was off grade-line, being about 220 mm too high at the far side. Fortunately sufficient working space remained to allow the 490 nun

21、pipe to be installed to the critical design grade and to be tied down by mcans of brick walls. NOTE: A repair job, if necessary in future, will necessitate breaking out the brick walls. b) Contract XYZ Crossing No. 3 : 300 mm sewer in 1 200 mm (not 1 125 mm) sleeve: This job went well because effici

22、ent de-watering was carried out. The larger size sleeve was used mainly because it was more readily available. SADS 0120 : Part 5 2 Sectlon LG-l983 Pipe jacklng 3.1.6 Cxcavatlon of the Face1). As the jacking procceds, excavation In front of the pipe should normally be carried out from wlthin the shi

23、eld but the preclse method of excavdtlon will be determined by sol1 conditions. The face may be mlned uslng pricumatic tools or hand tools as may be nccessnry, and the excavated matcrlal loaded 111to sklps for transfer to the thrust pit. The face may need supFortlng by face boards and, when excdvati

24、ng, the mlner should exercise every care. 3.1.7 Checkng Lmc and Level1). Durlng excavation and jacklng frcquent checks on the Line and level should be made from a flxed reference and any adjustments made by using jacks lncorporated in the shield. 3.1.8 Settlements (Subclause 5.4.3.1) 3.1.8.1 In view

25、 of the importancc of rallway llnes and public roads undcr which a plpc may be jacked, should any settlement bc observed In the viciruty, work should cease nunedlatcly, and should not be rc-comenced untrl satisfactory measures have bcen taken to prevent any further settlement. 3.1.8.2 Note that the

26、rcqulrements of Subclause 5.4.3.2(e) of SABS 1200 LG, though necessary, will cause problems For the contractor and add to his costs (see 5.4.3.2(f) of SAHS 1200 LG) because of the inevitable lrlcrease In pressure caused by any form of grouting durlng lacking. 3.1.9 Steps to Reduce Jnckng ForcesL (Su

27、bclauscs 4.1 and 5.5.2). To rrducc jackmy forces, t may be necessary to reduce frlcilonal resistancc by applylng sultnblc lubricant to the outslde of the pipe,. ceitaln clays wlth the chardcterlstlcs of volcanlc ash have bcen approved tor thls purposc. Jacklng forces may also be reduced by the use o

28、f lntermcdlate lacking stations. A steel cylinder, havmg hydraulic jacks placed around the perlphcry at one end and bearmg agalnst purpose-made dlstrlbution pads or rlngs, is introduced between two mterjack plpes. As the plpelltie moves forward the intermediate 2,icks are dctlvatfd and the forward p

29、art of the plpellnc 1s moved on. At the end of the stroke of the ntcrmrdlate jacks, the pressure on them 1s removed and the main jacks In the thrust plt are actuated, inovlng the rear part of the plpellne forward and closlng the mtermedlate statlon jacks. Or completlon of the plpellne, the ntermedat

30、c jacking statlon 1s removed and the znterjack plpes are clcsed to form a unctlon. 3.3.10 glpe to be kept Movlny durlnrj Jacklng (Subclauses 4.4 and 5.5.2). If tlic jacklny of a large dlamcter or a long length oi plpeline 1s rriterrupted for any length of tune when a substaritlal length of pipeline

31、has been jacked, the acklng force requlred to restart the “frozen“ plpe may exceed the capaclty of the dcl:s, the strength of the plpes or thrust rlng seatlng, or the resistance of the thrust blcck. Lightlng should be provlded and arrangements made for jackiny to be continuous to avold such problems

32、. (See also 3.1.12 below.) 3.1.11 Krovlsion for Lubricdt20n. The contractor should form holes 111 plpo walls as they may be needed for the njectlon of a lubrlcatlng merliunl or grout should the plpe show slgns of “ireezlng“. 3.1 .l2 1:arLh Res stance. to ?sing Loads 3.1.12.1 On a particular prolect

33、that riecessitatcd jacking a 1 500 mm sleeve pipe 15 m in length, the earth resistancc was stralned to the limt eve11 after emergency extensions of thc thrust block and extra earth loads had bcen addrd. On completlon of the jacklng thc thrust block was found to be badly ulsplaccd and cculd not have

34、wlthstrood more than the thrust of 1 700 kN that was actually requlred. J.1.12.2 I.rlctzond forces of up to 100 kN pcr square metre of plpe surface area were reported during jacking at the Durban Bluff. 3.1.13 Mdj,ntainlrig Allqnncnt. A plan-ended plpe wlthout an arrangement to malnialn alignment 1s

35、 not satlstactory as a lead pp. In addltlon, all surfaces at the ends of ppes through whlch the jackng iorce ss trarismtted should be plaln arid square to the plpe axls. 3.1.;4 Suwrvislon. Jacklng should be supcrvlscd and undertaken only by men fully tralned and experienced in ths work. 3.:.15 Toler

36、ances (Subclause 6.1). The tolerance at the leadlng edge of the jacked sectlon shoulc: be permitted to be plus only or mlnus only In the cases of downhill or up11111 jacking, rcspectluely, m crdcr to avoid a backfell 111 connecting manholes or junctlon boxes. (See also 2.3 above.) 3.2.1 Special Cqul

37、pment for Plpe Jacking (Subclause 4.1). SpecLa1 cqulpment should lnclude the cuttlng edge, tlir shleld and steerrng arrangement (see Subclause 4.3 of SABS 1200 LG), the thrust seatmy ring, guide rals, eLc. The use oE nteracks may be consldercd where problems lri provldlng adequate earth resstalice f

38、or the thrust block are expected. 3.2.2 hrust lt Length. The attcntlon of the englneer and the contractor 1s drawn to Subclause 2.3.3 of - scctlri 1.G of Part 3 of the code. Tlic contractor should not excavate the pipe trench approaching the thrust plt until dcclsluns on thc location of the thrust b

39、lock have been made. Plenty of undisturbed ground should bc left to provide adequate rcslstance to the jacking forces. 3.?.3 Plpcs to bc of Adequnte Strength. The lackmg iorcc is dcpcndcnl on the equlpmcnt used by the culltractor, and the maxmum longltudindl force to be apilicd durlnj jackmg operati

40、ons should be made kncwn by the contractor to the suppler when the pipcs are ordcred. (See also 3.1.1-3.1.4 above.) l) Abstracted from Jacklng concxete plpes published Jointly by the Plpc Jackirlq Associatlon and the Concrete Plpe Assoclation of Great Britam In June 1980. SABS 0120 : Part 5 Section

41、26-1983 Pipe jacking 3.2.4 Precautions when Jacking under or near Buildings. The contractor should be punctilious in xhe examination of nearby property before jacking is started and in keeping a record of the condition of the property. 3.2.5 Intermediate Jacking Stations (Subclause 5.5.3). It may un

42、der certain circumstances be desirable to use jacking pits intermediate between the manholes or junctions shown on the drawings. Such intermediate jacking stations should be permitted only where conditions of access and working space permit. On completion of jacking operations a junction box should

43、be constructed as a closure between the ends of the jacked pipes at each intermediate jacking station. Such junction boxes should be constructed to approved detail drawings. 3.2.6 Blasting (Subclause 5.2.5). Pipe jacking may become hazardous when rocks occur in an embankment. Even though an item may

44、 be included in the schedule for the removal of rock by blasting, Subclause 5.2.5 of SABS 1200 LG states that no blasting will be permitted without the written permission of the engineer. Such permission should be granted only as a last resort and the operation carried out under very strict control

45、by all parties concerned. 3.2.7 Occupation Details for an Alternative “Cut and Cover“ Construction. The following is a brief report on preparatory work for the crossing of a busy SAX track carried out under conditions imposed by the South African Transport Services: The contract covered the installa

46、tion of a 1 100 mm diameter concrete pipe (1350 D load) to serve as a stormwater drain. The South African Transport Services gave the contractor occupation on a Sunday morning from midnight to 06h00 for jetting-in long RSJ whalers (for the support of shoring later), and then provided topstrapping wi

47、th married rails to support the rail tracks over a maximum trench width of 2,5 m. (See Subclauses 1.1.1 and 1.3.3 of Section LG of Part 3 of the code.) QUALITY CONTROL AND OTHER CONSIDERATIONS QUALITY CONTROL. Apply the relevant recommendations of SABS 0157) to the jacking of pipes. DISPUTES. If the

48、 data called for in terms of Subclause 1.1.2 of Section LG of Part 3 of the code are not adequately provided, disputes are likely to arise in the form of claims for extra payment under Subclause 8.2.1 of SABS 1200 LG, which claims may exceed the stated sum provided under Subclause 8.2.5 of SABS 1200 LG. 2) Quality management systems.