The piers are all flat column piers, with a width of 5.40m, a thickness of 1.2m, a side groove depth of 20cm, and a U-shaped abutment with a 5.8×5.8×2.0m cap at the lower part.
1 pile cap construction
Excavator-assisted manual excavation is adopted for foundation pit, and steel bars are uniformly processed and bound on site. The formwork is a large steel formwork, which is reinforced by "top pulling" method, that is, the inside is provided with full-length PVC pipes, and the outside is supported on the pit wall with square wood. Concrete is poured in layers from the four corners to the center through the chute, vibrated with a vibrating rod, and watered for curing.
2 Wharf construction
Due to the low height of pier, formwork pouring is completed at one time.
2. 1 steel binding
Before construction, check the position of embedded steel bars before binding, and adjust them in time if there is any deviation. The steel bars are bound in place, and the construction scaffolding is bowl-shaped scaffolding, which is set up in double layers around the pier, and the working platform is set up between the top supports with wooden boards.
2.2 Template design and installation
Rigid large steel formwork with a thickness of 6mm is adopted. Template design for three kinds of standard template, angle steel as cross rib, each template length is 4 ~ 5m, configuration short section template. The formwork is connected with bolts and reinforced with small trusses and two longitudinal ties. The vertical spacing of trusses is 1.0m, so long lacing is avoided. The reinforcement scheme is shown in Figure 5.2- 1. Clean the template and apply release agent as required. Template cracks can be clamped by grouting strips, and assembled by hand with truck crane. The protective layer is set on the main reinforcement according to the design thickness, and the template is fixed by the ground anchor.
2.3 concrete pouring
After the concrete is pumped to the working platform at the top of the pier, it is poured in layers through a series of rollers and funnels, and each layer is 30-50 cm thick. Concrete shall be vibrated manually with a vibrating rod, and the pumping speed of concrete shall be properly controlled to reduce the lateral pressure of the formwork. At the same time, designate a special person to position and tamp to prevent insufficient or excessive vibration.
The pier position, supporting cushion stone and pier body of uncovered beam shall be constructed at the same time. The position and elevation of the cushion stone should be set at the pier top, leveled with a high-precision level, plastered by manual secondary grouting, compacted and polished, and corresponding embedded parts and holes should be reserved according to the design, so that the cushion stone concrete can be integrated with the pier body.
2.4 template removal and maintenance
Before form removal, the formwork should be protected from impact or vibration, and the time of form removal should be determined through experiments. Under normal circumstances, after the concrete strength reaches 2.5Mpa, it can be dismantled by hand with a truck crane in blocks, and then it is wrapped and cured with a film after formwork removal.
3 capping beam construction
For the pier with capping beam, the side formwork and bottom formwork of capping beam are both large steel formwork, which are constructed with full bowl buckle bracket, assisted by truck crane and pumped by concrete pump.
After the foundation is leveled, it will be tamped with frog rammer, and bowl-shaped brackets will be set in plum blossom shape, and concrete cushion will be laid under the brackets. Laying the square timber on the support, and finally laying the steel plate as the bottom template.
The steel bars are bound on the bottom formwork, and the side formwork is manually installed with the help of a truck crane. The lateral triangular truss rib is connected with the bottom square beam, and the top is "support", as shown in Figure 5.2-2.
Cushion stones should be poured together with capping beams, and the plane position, structural size, elevation and height difference of four corners of the cushion stones should be strictly controlled. Before pouring, carefully check the reinforcement, formwork and reserved channel, etc. Construction shall be carried out after acceptance. After the capping beam is cured to more than 75% strength, the support and bottom formwork should be removed symmetrically from the middle of the span to both ends.
Fig. 5.2-2 Schematic diagram of reinforcement and support of capping beam formwork
4 abutment construction
The construction adopts large steel formwork, which is mainly strengthened by external bracing. Due to the low height of abutment, it is poured at one time.
Bowl-shaped bracket and steel formwork are used for the construction of the bearing platform, and the platform body, bearing platform and cushion stone are poured at one time. After the formwork and steel bar binding inspection are qualified, concrete will be poured directly with a pump truck, which will be tamped manually, and the cushion stone will be set with the pier. After the top surface is plastered for the second time, it is covered with plastic film for curing. After the concrete strength reaches above 2.5MPa, the formwork shall be removed. After form removal, continuous sprinkler maintenance shall be carried out for at least 7 days.
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