The Replacement of West Berth’s rubber fenders in Shenzhen Sinopec Dapeng Bay wharf

It has been provided with two berths that located in the east and west of Shenzhen Sinopec Dapeng Bay oil depot Wharf, and the west berth’s dead weight tonnage level is 14000, in addition, it possesses two breasting dolphins which are installed “π” shaped 1000 H × 2500L rubber fenders as anti-collision installation (As shown in Figure 1). Under the background of changes in market conditions and the requirement of itself business growth, Shenzhen Sinopec Dapeng Bay Oil Depot Wharf  had drafted a scheme which was changed the dual old “π” shaped rubber fenders into SC1250H (one cell one panel) cell rubber fenders by way of improving the running capability and throughput. The project implemented through tender.

Figure 1     “π” shaped 1000 H × 2500L rubber fender 

The Technical Specification bidding documents required that we should adopt pre - buried sleeves, foundation pole, base anchor and screw bolts as fastening piece for cell rubber fender. Another conundrum had appeared unexpectedly, the 2.3 ordinance of the tender document demanded to complete the site demolition of old fenders and installed new fenders within seven days, however, after reviewing the construction program, only 4 days of construction period had been approved.

Figure 2 shows the embedded and connected components used for installing SC1250H cell rubber fenders. We can learn from figure 2 that 

the size of base anchor 5 is φ110 mm which is an assembly of anchor bar 4 and the total length of the embedded sleeve assembly 3 is 500 mm. We had to drill out the hole which the diameter of the hole was greater than φ 110mm and the depth was greater than φ 500mm to pre-buried it. And a set SC1250H cell rubber fender fixed by six M45 specifications bolts (As shown in Figure 1). In other words, only drilled the above specifications φ 110 mm × φ 500 mm of the six deep holes and pre-buried the sleeve type components, could we carry out the installation of the SC1250H cell rubber fender.

Figure 2  fastener used for SC1250H cell rubber fender installation

Figure 3  SC1250H cell rubber fender’s ontology structure diagram

On the pier's breast wall lie in west berth of Shenzhen Sinopec Dapeng Bay oil depot Wharf, as shown in figure 3, it was necessary to drill the six φ 110 mm × φ 500 mm size deep holes evenly on the circumference of φ 1450mm in diameter, it must comply with the design of the provisions of the fender, which is located in where included the design of its high water level and design low water level. Two of the 6 holes in the fender must be submerged at regular intervals, that means under the surface of the water can be carried out drilling operations, only take advantage of the ebb tide of the sea, when the hole is out of the water surface, the construction can be carried out and we must consider the tidal changes in the water that will had an impact on the construction.

2.1.Examined on the spot, seek out a good method to dismantle old fenders

First of all, we had Launched a full investigation about installing screw bolts which were belonged to “π” shaped rubber fender: site identification bolt specifications, material, in use state, the relevant dimensions of the bolt installation were measured one by one and verified with the corresponding “π” shaped rubber fender drawings to get accurate information. Then field mapping the location and distance of the buildings on the pier plane that offered a reference to the size of the site required to install the SC1250H(one cell one panel) cell rubber fenders.

Through examined on the spot to comprehend the water area and their surroundings, we had came up with a feasible method about removing old “π” shaped rubber fender: “π” shaped rubber fender was removed as a whole with the fender front panel, then they would be carried away by hanging ship. The point of this solution was that all posts need to be prepared, the loading vessel should be pre-entered into the berth waters, crane on the pier should pay attention to the demolition workers on the pier's breast wall, once all the bolts were released, immediately lifted the whole “π” shaped fender to the ship and carried away.

Figure 4 The overall removal of “π” shaped fenders on-site photo

2.2.The new plan of installing cell fenders reached a consensus

As far as The Technical Specification bidding documents required that we should adopt pre-buried sleeves, anchor bar, anchor plate and bolts as fastening piece for cell rubber fender is concerned, If we used the embedded and connecting components to install the drum rubber fender, it’s usually synchronous construction with the new berth which is the first pre-buried sleeve, anchor bar assembly and pier steel chain together, then the concrete pouring, achieving the anchor bar assembly sleeve embedded after pouring piers. As regard to install and replace the new type rubber fenders, it was not suitable for adopting pre-buried sleeve assembly, there were some reasons:

(1)As mentioned earlier, Suppose we installed cell rubber fenders with pre-buried sleeve assembly, there are two major difficulties that are construction and environmental factors, it’s unable to accomplish within the expected time. 

(2)If we wanted to install pre-buried sleeve assembly, must refit the pier, the way of burying related fastening piece was that we used high-power diamond equipment evenly drilled six φ 110mm × φ 500mm deep holes in the diameter of φ 1450 mm circumference. But there's a problem at this point, it was certain to destroy pier and the main rebar which was buried in the internal structure of reinforced concrete pier when we drill the holes, it directly affected the bearing capacity and the operating life of pier.

Therefore, installing cell rubber fenders with “site board device ” could greatly shorten construction time that ensured within the prescribed period of time to complete the new fender installation, but also could make the pier will not be damaged by the construction and maintained the integrity of the pier.

3.1. Rationality of structure

Site board device as shown in figure 5, the specification is 2000 mm × 3000 mm × 20 mm.

Figure 5

Drilling out 16 oval holes on the around and middle of the site board which corresponded with position of fastening bolts belonged to  “π” shaped rubber fender (As shown in Figure 1), and utilizing the original 16 M48 bolts installed on the old rubber fenders fixes the positioning plate firmly on the chest wall of the pier. And then follow the design requirements, at the predetermined position of the positioning plate (The intersection of longitudinal 1000 and transverse 1300 in Fig. 5), made a circle with a diameter of 1450 mm, in addition to evenly install 6 M45 bolts (Figure 5) let SC1250H (one cell one panel) cell rubber fenders firmly attached to the positioning plate (As shown in Figure 6). 

Figure 6 Installing the cell rubber fender on the positioning plate

The positioning plate was used to install the drum rubber fender to ensure that the installation position met the requirements of the original design of high water level and low water level of the wharf.

3.2.Analyze the force of the locating plate

There were two piers in west berth and each pier with a “π” shaped 1000 H × 2500L rubber fender in earlier times, every “π” shaped  rubber fender consisted of two rubber support arms and a frontal frame, and each rubber support arm is secured by 8 M48 bolts (As shown in Figure 1). 

It was understood that since the west berth was put into operation, there has never been that single rubber support arm falls off “π” shaped rubber fender, also never found that steel plate in rubber support arm has been pulled out. This explains that prefabricated fastening bolts for rubber fenders were capable of tightly locking rubber support arm in any operation of the pier. In that way, the newly designed site board of which area and thickness exceeded the sum of the total area and thickness of the two steel plates inside the fender, at the same time, the positioning plate was fixed by the M48 bolts for the 16 mounting fenders. By comparison, the reliability of the site board would be greatly enhanced.

3.3.Calculation of bearing capacity of positioning plate

Checking the mounting capacity of the positioning plate for the SC1250H (one cell one panel) cell rubber fender, expressed by the formula:  

Where:

P– the carrying capacity of the positioning plate (Q235 model steel plate), kN,

δ – represents the tensile strength of the steel plate, 380 N / mm²

d– represents the effective diameter (M45 bolt hex head), mm

h– represents the thickness of the positioning plate, mm

That is: P =δπdh =380 × 3.1416 × 74.54 × 20 =1778.8 kN

According to the “ technical specification ”, the main performance index of rubber fender required that SC1250H (single cell) cell rubber fender was high reaction force type (RS), when the deformation of the cell type rubber fender reached the maximum 55%, the counterforce R=1 109 kN, with the site board bearing capacity compared : P ＞ R, that means the structure of the site board is safe, and the carrying capacity meets the requirement of the berthing of the 14 thousand ton oil tanker.

Installation completed SC1250H cell rubber fender as shown in Figure 7.

Figure 7

1.Successfully applied the site board to install the SC1250H (one cell one panel) cell rubber fender, the contractor fulfilled the promise made in the tender:

2.Set the site board to install SC1250H (one cell one panel) cell rubber fender was not just solving the Sinopec Dapeng Bay Oil depot wharf west berth replacement rubber fender construction problems, more importantly, in the whole construction process did not give berth (pier) damage, to maintain the integrity of the terminal. This experience can be used as a reference for the renewal or upgrading of anti-collision facilities in similar operating docks or berths.

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