SANS 10120-5 DK-1996 Code of practice for use with standardized specifications for civil engineering construction and contract documents Part 5 Contract administration Section DK G.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 01 20-5 Section DK:l996 Gabions and pitching First revision Part 5 : Contract administration Section DK Contents 1 Startofconstruction . 1.1 General

4、 2 Immediately after the handing over of the site . . 2.1 General 2.2 Geotextile or geomembrane 3 Duringconstruction . 3.1 Methods of construction 3.1.1 Qualityofstone . 3.1.2 Constructionofagabion 3.1.3 Quality of finished work . 3.1.4 Examples of gabion structures 3.1.5 Stonequalityandtests . 3.2

5、Administration 3.2.1 Preparation of foundation for gabion construction . 3.2.2 Toe french for pitching 3.2.3 Testingstone 3.2.4 Field tests on lacing 4 Quality control and other considerations . 4.1 Quality control 4.2 Disputes 4.2.1 Preparation of bedding for gabion construction Drawings Gabion box

6、 construction (Figures 1 to 11) Gabion mattress construction (Figures 12 to 22) First revision 24 June 1996 This section of the code supersedes SAW 0120-5 : Section DK:1984 Approved by the PRESIDENT OF THE SOUTH AFRICAN BUREAU OF STANDARDS CODE OF PRACTICE SABS 01 20-5 : Sectlon DK:1996 SABS 1200 DK

7、 : Gabions and pitching NOTE - The clause number(s) given in brackets at the beginning or after the heading of a clause idare, unless otherwise stated, the number(s) of the relevant clause(s) of SABS 1200 DK. 1 Start of construction 1.1 General For the purposes of this part of the code, contract adm

8、inistration starts with instructions to the contractor to commence work as set out in 4.1 of the Introduction to the code. 2 Immediately after the handing over of the site 2.1 General The engineer and the contractor should agree on the arrangements to be made for approval of excavated foundations as

9、 soon as the foundations are ready to receive gabions or toes for pitching, as applicable, and the engineer should give immediate attention to all other matters necessary to ensure that the start of the contract is not adversely affected by lack of information. 2.2 Geotextiie or geomembrane (3.1.3 a

10、nd 3.1.4) Where the contract requires that the contractor provide a geotextile or a geomembrane, he should (immediately after the award of the contract) advise the engineer of the make and grade of geotextile or geomembrane which he proposes to use, and obtain the engineers approval before placing t

11、he order for the delivery of the material. (See also l .l and 3.2.2 of section DK of SABS 0120-2.) 3 During construction 3.1 Methods of construction 3.1 .l Quality of stone (3.1 .l, 7.3 and 7.4) The contractor is required to supply stone that complies with the specification and, should he have any d

12、oubts as to its durability or its ability to withstand weathering, he should, at his own expense, carry out the appropriate tests. The engineer is entitled to expect that the stone being used will comply with the relevant requirements. He may, if he so wishes, arrange for the appropriate tests to be

13、 carried out and the costs of these tests must be borne by the contractor if the stone fails to comply with the relevant requirements, and by the employer if it does comply. 3.1.2 Construction of a gabion (5.2.3) 3.1.2.1 General In general, tightness of mesh, well-packed filling, and tightness of la

14、cing are essential in all gabion structures. Pairs of wire braces, each wire of nominal diameter 2 mm, are generally sufficient to prevent the deformation of a cage if they are provided at the rate of 4 braces per cubic metre of gabion volume for gabions of depth up to 1 m. Gabion cages of de th exc

15、eeding 1 m should not be constructed. Details of a manufacturels recommended method of P construction ) of a gabion box and a gabion mattress are set out in 3.1.2.2 and 3.1.2.3, respectively, below. 3.1.2.2 Gabion box 3.1.2.2.1 Assembly Unfold each gabion on a hard, flat surface. Stretch it out and

16、stamp out any unnecessary kinks. Make sure that all creases are in the correct positions for forming the box: one for the edge of each end, back and side panel and the lid, and one for each diaphragm (see figure 1). Fold the back, front and end panels into the upright position to form a rectangular

17、box. Join together the top corners of the box with the thick selvage wire sticking out from the corners of each panel. This ensures that the tops of all four sides of the box are level (see figure 2). Begin wiring-up by looping an erid of the binding wire through the top corners of the panels to be

18、joined and twisting the end around the binding wire to secure it. Then lace the wire around the selvages with alternate single loops and double loops at 100 mm intervals (see figure 3). Finally, fasten the wire securely at the bottom corner and poke the loose end inside the gabion. 1) Abstracted and

19、 reproduced with permission from a manufacturer of gabions. SABS 0120-5 Section DK:IW6 Gabions and pitching First revision Next, lift the diaphragms into the vertical position and wire them up to the back and front panels in exactly the same way. NOTE - Tightness of the mesh and wiring is essential

20、at all times. 3.1.2.2.2 Forming the structure Before placing the empty gabions in position, level the site of the structure as much as possible. Once the gabions are in place, it is difficult to remove unwanted material from underneath them. Where possible, wire small groups of empty gabions togethe

21、r off the site, and then carry them to the structure as complete sections for joining to other gabions already in position. This is easier than wiring all of them on site, especially when working in water. Wire the gabions together, using exactiy the same method as for assembling single gabions (see

22、 figure 4). Place them front to front and back to back, so that pairs of facing lids can later be wired down at the same time (see figure 5). 3.1.2.2.3 Stretching gablons before filllng Place the empty gabion or group of gabions in position. By means of rods driven through the two corners into the g

23、round and tied firmly to a good anchorage (see figure 6), secure the end from which work is to start. To prevent the gabion from collapsing, it is important that the length of the rods be such that the rods extend to at least the height of the gabion. Wire the remaining empty gabions one to another

24、as work proceeds (see figure 4). Stretch the opposite side or end of each gabion by inserting bars into the bottom corners and levering them forwards. Keep the top and bottom stretched by tying them firmly to a good anchorage (e.g. a stake driven into the ground) until the gabion has been wired to t

25、he gabion below and filled. Alternatively, in suitable conditions (e.g. in the construction of a relatively long, straight structure), use a mechanical strainer instead of stretching each gabion separately. Firmly secure one end of a row of previously wired-together empty gabions to a good anchorage

26、, and attach the other end to the strainer by means of rods and a spreader bar. When sufficient tension has been applied over the length (of up to 30 m), wire the gabions securely along the sides and ends to the adjoining gabions. If they form the second or a higher course, wire them to the already

27、filled gabions below, and then fill them, or, if they form the base course, fill them immediately. While the gabions are being stretched, check that the wiring has been properly carried out. If any section is found to be pulling apart, the section must be re-wired. 3.1.2.2.4 Filling and securing lid

28、s Use hard, durable stone not larger than 250 mm and not smaller than the nominal size of the mesh. The optimum size range is 120 mm to 200 mm. A small percentage (about 5 % to 7 5%) of smaller material is allowable (see 3.1 .l of SABS 1200 DK). In areas where large fill is difficult to obtain, line

29、 the compartment with large stones and fill the interior with smaller stones (see figure 7). Fill the gabions by hand or by machine, making sure that the stone is tightly packed and has a minimum of voids. When possible, leave the last gabion empty, since this makes it easier to join the next one to

30、 it. Fill all the outside compartments of 1 m deep gabions only one-third full, to begin with (see 5.2.3 of SABS 1200 DK). Then fix horizontal bracing wires in the gabions directly above the level of the stone in those compartments and apply tension to the bracing wires (by twisting them together) t

31、o keep the face even and free from bulging (see figures 8, 9 and 10). Next fill the gabions to two-thirds full, and repeat the bracing (see figure 9). Finally, fill the gabions to the top. Level off the fill 25 mm to 50 mm above the top of the mesh to allow for settlement. Small material is best for

32、 this. Fill 0,5 m deep gabions in two lifts and fix bracing when they are half full. No bracing is necessary in 0,3 m gabions. In aprons downstream of weirs and in similar places where water falls direct onto the gabions, fit vertical bracing wires between the top and bottom mesh. 3.1.2.2.5 Securing

33、 lids Stretch the lids tightly over the filling and wire them down (see figure 11). First secure the corners temporarily to ensure that there is enough mesh to cover the whole area. Some filling might have to be removed from the top of the gabion to prevent the lid from being over-stretched. 3.1 2.3

34、 Gabion mattress NOTES 1 Carry out all wiring as a continuous lacing operation, not with individual twists of wire at intervals. 2 Tightness of the mesh and wiring is essential at all times. SABS 01 20-5 Section DK:l996 Gabions and pitching First revision 3.1.2.3.1 Assembly Stretch out each mattress

35、 on a hard, flat surface, and stamp out any unnecessary kinks (see figure 12). If the finished mattress is to be less than full-length, cut off the fength required (see figure 13). Raise to vertical the sides and ends of the mattress and the diaphragms. Check that the height of both sides is the sam

36、e and that it is correct. If the sides are of different heights, so adjust the position of each diaphragm that the sides hinge-up on the thicker selvage wire woven in the mesh. Pull each diaphragm upright to the same height as the sides, and attach it temporarily to the sides by bending the short le

37、ngths of selvage wire protruding from the ends of the diaphragm, firmly over and around the tops of the sides. Pull out the ends of the helical wire connecting each diaphragm to the bottom of the mattress, and use this wire to fix the diaphragm ends to the sides (see figures 14 and 15). Pull out onl

38、y enough wire to do the wiring. At the four corners, so bend the projecting lengths of the end panels that they overlap the sides, and lace the ends up with binding wire. If the mattress is to be placed over a geotextile or geomembrane, take care to ensure that projecting ends of wire are bent upwar

39、ds to prevent them from puncturing or tearing the geotextile or geomembrane. Carry the wired-up mattress to its final position, and wire it securely to the adjacent mattress(es). On slopes, the mattress should be laid with the shorter dimension along the slope, not up and down Et (see figure 16). Pl

40、ace and wire mattresses together while they are empty, since it is difficult to wire two mattresses together when one is full of stone. Place the fill material, by hand or mechanically, in the compartments, starting at the bottom if on a slope (see figures 16 and 17). The fill should be a hard, dura

41、ble stone, of size between 75 mm and two-thirds the thickness of the mattress, except that for marine work, the minimum stone size should be 150 mm. Filling can be done unit by unit, but several units should be ready for filling at any one time. After filling each mattress (ensuring that it is sligh

42、tly over-full to allow for settlement), securely wire the lid to the tops of the sides, ends and diaphragms, using alternate single and double loops (see figure 18). If more than one mattress has been filled, wire down the edges of adjacent lids in the same operation, since this will save both time

43、and binding wire (see figure 5). 3.1 23.2 Steep slopes When a mattress is laid on a slope steeper than 1 in 1,5, secure it by means of hardwood pegs driven into the ground just below the upper end panel, at 2 m centres or at whatever spacing is considered necessary (see figure 19). 3.1.2.3.3 Cut len

44、gths It is often necessary to shorten mattresses to fit the structure being built, by cutting off a number of compartments. The off-cut, which has an open end, can be used in two ways: a) by wiring it direct to a whole mattress, to lengthen it (see figure 13); or b) by using it as a short mattress t

45、o fit a particular part of a structure (see figure 20). In the latter case, finish the open end after filling the mattress, by folding down the sides and the top to form a wedge shape and wiring them down. On slopes, ensure that this wedge-shaped end is at the top. 3.1.2.3.4 Curves Cut a mattress in

46、 one of the following ways to fit difficult curves: a) Cut the mattress diagonally to form two triangular sections, and butt-join the open side of one section to the intact side of the other (see figure 21). To modify the curve, place whole mattresses between triangular sections. b) Place whole unas

47、sembled flat units in sequence and overlapped to suit the curve (see figure 22). Place the first unit on the curve at the end of the straight section, with one side raised and laced to the end unit of the straight section. Raise the exposed sides of the units lying on top. Cut the diaphragms along t

48、he lines of these sides and pull them upright. Then proceed with the assembly as described in (a) above, starting from the second paragraph. 3.1.3 Quality of finished work) The construction of gabions that have a neat, regular appearance or that have a true face is possible, provided that the contra

49、ctor, in addition to observing the recommendations given in 3.1.2 above, also takes the applicable of the following precautions: a) Prevention of bulging: prevent any initial bulging by wiring the adjoining boxes to the first box to be filled, before any stone is placed, and then commence the placing of the first one-third layer of stone in the adjoining box immediately after the wire braces above the first layer in the first box have been tightened and the placing of the second one-third layer in the first box has commenced. (Wire braces comprise a pair of 2 mm binding wires stretched from