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Repair of dock Y-type rubber fender or cylindrical rubber fender fixing bolt
Edit: Jiangsu Ahn Jin Rubber Co., Ltd.Date: 2018-08-24

Abstract: This paper introduces the on-site repair design, construction and inspection methods of Y-type rubber fenders and cylindrical rubber fender fixing bolts. It has been proved that the repairing scheme is technically reliable, low-cost, easy to operate, simple and feasible.

The 9~12# berth anti-shooting equipment of Lianyungang Terminal is D800-LIOOO Y-type rubber fender cylindrical rubber fender. The fender is suspended in the iron card nostrils on the quay wall of the dock, and the card nose is fixed by four Q235 steel M30 bolts. The card nose is often damaged by the impact of the ship due to the prominent shore wall of the wharf. This article describes a simple and easy way to repair bolts.

First, repair design
The conventional force to repair broken bolts: two bolts of butt weld fracture or reburied. Obviously the scene can only be repaired with the latter.

The bolt specification model adopts the original design, that is, M235 bolt made of Q235 steel, and the buried length is the same as the hole depth, which is determined by calculation. In order to make the bolt firmly adhere to the filler in the hole, the surface is processed into a thick thread.
2. Aperture and hole length
(1) Aperture
The hole diameter is determined by the bolt diameter and the thickness of the packing. When the filler thickness t is 5 mm, the aperture D=D snail + 2t = 30 + 5 × 2 = 40 mm. The aperture is as small as possible inside and outside, and is rounded.
(2) Hole depth
Calculation formula of hole depth L
The maximum tensile force of the N-bolt in the formula is calculated based on the specification and type of the original design bolt, the number and the suspension height of the Y-type rubber fender, etc. to calculate the external force (the ship's pressing force and impact force) received by the fender bolt; - The bond strength between the filler and the concrete wall, the filler and the bolt, according to the specifications.
3. filler
The filler is made of sulfur mortar with fast solidification and high bonding strength. Its weight ratio is sulfur: cement: yellow sand: paraffin = 1:0.4:1.2:0.003. The specification stipulates that the bond strength between the sulphur mortar and the concrete hole wall and the bolt is not less than 4 MPa and 11 MPa, respectively. The former is smaller than the latter, indicating that the sulphur mortar and the concrete hole wall are loosened before the sulphur mortar and the bolt. Therefore, take (= 4MPa:
4. External force and hole depth calculation
The bolt force diagram is shown in the drawing.
The combined tensile force formed by external force and eccentric force of each bolt is calculated by the force diagram, and the shear and tensile strength are calculated. The shear strength is used as the control condition to calculate the external force P. Consider a safety factor of 1.5. Ship crushing unevenness coefficient L 3. Calculate N: ax, substitute (11 type, get L > 302mm take the hole depth L = 320mm

Second, the implementation
1. Artificial hole
The artificial hole is formed by hammering steel, and after the hole is formed, the hole should be carefully cleaned. Holes should avoid the main ribs.
2. Buried section
After the hole is formed, the anchor bolts should be buried in time to prevent the tide from being poured into the holes to reduce the bond strength. Sulfur mortar filling - must be full, sulfur mortar must be used within 5 minutes after mixing.

Third, the repair effect test
The test method is pre-buried according to the site conditions - set of 3 M30 bolts, buried depth 200mm. With the oil pump, the jack is connected with the top of the jack, and the bond strength is calculated by loosely pulling out the instantaneous oil pump pressure gauge reading. Tested by:
Tensile strength N = 6 sticky DL = 297571.7 (N) > N: ax, both meet the design and specification requirements. In addition, when the bolt is pulled out, the bolt and the sulphur mortar are tightly wrapped without any looseness, and the bonding strength is higher than that of the concrete hole-sulfur mortar.
Practice has proved that the Y-type rubber fender adopts the repairing scheme of re-buried bolts, which is technically reliable, low in cost, simple in operation, simple and feasible.