1, reinforcement construction

All steel bars are cut, bent and bound in the steel bar processing plant. In order to facilitate the construction, the pier reinforcement has been bound on the ground, and it is hoisted and embedded during the construction of the pile cap reinforcement, and welded and positioned. After hoisting, anchor the pier reinforcement around with three steel wires.

2, template and support construction

(1), template processing

Pier and abutment are made of shaped steel formwork and processed by factory.

5㎜ thick steel plate is used for the steel formwork panel of pier body, and vertical ribs and purlins are set on the outer side of the panel. The vertical ribs are made of 8 # channel steel with a spacing of 35cm. Purlins are made of 12.5a channel steel with a spacing of 50㎝, and the joint surfaces are continuously welded. Each template consists of two semi-circular steel molds, and the joint is welded with a connecting steel plate with a thickness of10 ㎝, and bolt holes are set on the steel plate every 30㎝, which are connected by M 16 bolts. Four pieces of square column steel formwork are spliced, positioning pins and φ 16 connecting bolts are set at the splicing seams, and the ends of corners of purlins are reinforced with φ 16 steel tie rods. See the figure below for the structural layout.

2 sets of template quantity plan.

In actual construction, the steel formwork will be made by the factory. Whether the vertical ribs and purlins of formwork are made of section steel shall be determined by the manufacturer. When steel belts are used, their spacing shall ensure the strength and rigidity requirements of the formwork.

2, template installation

After the pier and abutment body is reinforced, the steel formwork shall be installed after it is accepted by the supervision engineer. When installing the steel formwork, use the crane to vertically hoist the steel formwork into the scaffold from the top of the column reinforcement. Before formwork installation, surveyors use total station to determine the center position of pier shaft, and determine the bottom edge line on the pile cap. After the formwork is folded and initially put in place, the formwork position shall be checked by vertical hanging method, and the steel formwork shall be moved by crowbar until the distance from the vertical line in the hanging method to the periphery of the formwork is equal to the radius of the column. When hanging vertically, the dimensions of the upper, middle and lower parts of the formwork shall be measured. After accurate positioning, fix the lower opening of the steel formwork, drill holes in the concrete with an electric drill according to the bolt hole position of the steel formwork of the pile cap, with the hole depth of 5 ~ 10 ㎝ and the diameter of 12 ㎝, and drive the short rebar head with φ 12 into the concrete of the pile cap. After four points are fixed around the steel formwork by the above method, the lower part of the formwork is fixed with diagonal braces, and the upper part of the formwork is fixed with steel wire rope. The upper steel wire rope is tied to the ground anchor or pile post through the inverted chain, as shown in the following figure. When the pier height is more than 2m, a concrete pouring operation platform should be set at the top of the steel formwork. The size of the cylindrical pier operation platform is (D+3.0)×(D+3.0)m, which is connected by scaffolding steel pipes. The horizontal steel pipe at the bottom of the platform is supported on the top of the steel formwork, the suspended part is supported by diagonal braces, and the lower end of the diagonal braces is inserted into the purlin gap of the steel formwork. The workbench is not shown in the figure below.

3, pier concrete pouring

The pier concrete is C30, which is mixed in the mixing station, transported to the construction site by car, and poured by 16T crane batching hopper. During pier pouring, a series of oil cylinders are set up because of the high blanking height. The concrete is vibrated with 1~2 vibrating rod, and the operator enters the pier bottom for operation. The vibration time of each insertion point shall not be less than 15 seconds. ZP22 planetary bar is used for concrete vibrating, and the thickness of layered pouring is 30㎝. The insertion points of vibrators are arranged in a quincunx shape, and the spacing is about 50㎝ (1.5 times the vibration radius). The vibrating time of each insertion point is 15 ~ 30 seconds, and the vibrating point can be replaced when the concrete surface is roughly flat, the liquid level no longer sinks, and no bubbles rise on the surface. Insertion point layout, but also pay attention to the template edge and corner position. The insertion point is about 15㎝ away from the edge of the formwork, so as to minimize the collision with steel bars and formwork. The vibrator should be inserted quickly, and it should be dialed slowly during operation to prevent air from mixing with concrete.

When pouring concrete, it should be 3㎝ high, so that the bottom formwork of capping beam can be closely attached to the pier shaft, so as to reduce the joint gap and prevent slurry leakage.

After concrete pouring is completed, it will be cured for 7 days. The pier maintenance adopts film wrapping measures to keep moisture and heat. Formwork and support can be removed after a certain period of time or after concrete pouring reaches a certain strength. The regulations are as follows: after 24 hours in summer, the pier formwork should not easily damage the concrete surface; The removal of formwork support should be carried out from top to bottom with the cooperation of crane. The support shall be removed from the previous floor. Before the vertical pole is removed step by step, all connecting rods shall not be removed, but all bars shall be removed step by step. After pouring is completed, it is wrapped with plastic film for curing.

Bridge Pier Construction Scheme (2)

I. Overview of the Project:

1, there are 2 inverted vase piers of 105 in this section of viaduct, including 17#, 18#, 19#, 20#, 83#, 84#, 85# and 86. C35 pier concrete 4500m? 780 tons of steel bars.

Second, the compilation basis and principles

2. 1 compilation basis

(1) Current national and Ministry of Railways construction technical specifications, acceptance standards, quality and safety technical regulations and construction guidelines.

(2) Geotechnical investigation report in the detailed investigation stage of Bid Section 3 of Dalian 202 Track Line Extension Project.

(3) Design and construction drawing of Dalian No.202 track line extension project in March 20 10 by the Third Railway Survey and Design Institute. Bridge site plan? 、? Full bridge layout? .

(4) Hydrogeological data and information obtained through field investigation and investigation.

(5) The time limit for a project issued by the General Command of Dalian 202 Track Line Extension Project on April 10? Have you noticed? .

2.2 Compilation principle

(1) According to the safety, quality, construction period, environmental protection and civilized construction requirements of Dalian 202 rail line extension project headquarters, strengthen quality management, formulate scientific construction scheme, reasonably arrange work schedule, work cycle and labor organization, and do a good job in process connection to realize safe production, ensure project quality and meet the construction period requirements.

(2) Rational allocation of production resources, adoption of advanced technology and equipment, completion of machine selection and matching, improvement of mechanical operation level, and implementation of standardized professional construction.

(3) Actively promote the adoption of new technologies, new processes, new materials and new equipment in the construction.

Third, the overall construction plan:

(a), the overall construction personnel, machinery, equipment arrangement:

1. Division of construction team: Bridge Team 1 is responsible for the construction of piers 67# to 32 #, including 44 piers and 1 abutment. Bridge No.2 Team is responsible for the construction of piers No.33 ~ No.94, including 6 1 pier and 1 abutment.

2, the construction team personnel, machines and tools, mechanical equipment:

(1) staffing: 24 steel workers, 6 welders, 6 formwork workers 12, 6 vibrators, scaffolder 12 and 8 general workers.

② Field machines and tools: 2 sets of 40KW generator sets, 2 sets of steel bar benders, 2 sets of stirrup benders, 2 sets of cutting machines, 2 sets of cutting machines, 6 sets of electric welding machines, 6 sets of water pumps and 0/2 sets of plug-in vibrators.

③ Mechanical equipment: equipped with 16T and 25T truck cranes 1 set, flatbed trucks 1 set, excavators 1 set and loaders 1 set. Concrete mixing and transportation equipment is provided by commodity mixing station: 50m mixing equipment? /h, 2 sets, 10 m? Transport vehicle 10, concrete truck pump 2, ground pump 1 set.

3, the construction of the second team personnel, machinery and equipment:

(1) staffing: 36 steel workers, 8 welders, 8 formwork workers 18 vibrators, 8 scaffolders 18 workers and 0/6 general workers.

② Field machines and tools: 40KW generator set 1, 100KW generator set 1, 2 steel bar benders, 2 hoop benders, 2 cutting machines, 8 electric welding machines, water pump 12 and plug-in vibrator 18.

③ Mechanical equipment: equipped with 16T truck crane 1 set, 2 25T truck cranes, flatbed truck 1 set, excavator 1 set and loader 1 set. Concrete mixing and transportation equipment is provided by commodity mixing station: 50m mixing equipment? /h, 2 sets, 10 m? Concrete truck 10, 2 concrete truck pumps, and ground pump 1 set.

Four, construction methods and technical guarantee measures:

(1) construction survey:

① Measuring instruments: one total station, one theodolite and two level meters.

(2) During construction, firstly, according to the coordinates of the center and axis control points of the pier, the position and axis control points of the pier are accurately measured and released from the traverse points on the pier foundation or the top surface of the bearing platform with the total station. Considering the high pier in this section, theodolite is used to control the verticality of pier during construction. After the formwork is set to the pier top, the position and axis control points of the pier top cap are accurately measured from the traverse points with total station, and the elevation of the pier top is rechecked and the embedded holes and positions are reserved.

(2), foundation pit excavation

The pile cap or pile foundation of this section of viaduct foundation is designed as a buried foundation, and the overlying soil is not less than 50cm. Foundation pit excavation should meet the requirements of construction operation platform and slope stability. The unstable pit wall of the foundation pit should be well supported. During the whole pier construction process, a sump should be left around the bottom of the foundation pit and set up. The surface and underground water levels shall be controlled by water pumps, and formwork and concrete shall not be soaked.

(3), steel engineering:

Steel bars shall be cut in the processing shed according to the construction drawings, and marked and bound at the site. When the pier height is less than10m, the pier column reinforcement will reach the top surface at one time; when the pier height is greater than10m, the pier column reinforcement and the reinforcement will be connected by lap welding. When welding, the secondary reinforcement adopts T506 covered electrode. When the vertical length of steel bar exceeds 6m, it should be temporarily fixed on the scaffold to prevent the steel bar from tilting vertically. According to the requirements of design documents, for durable concrete, pads must be placed on the outside of steel bars to ensure the thickness of protective layer of steel bars and prevent steel bars from being exposed. During construction, the concrete is vibrated internally, and there are four layers of steel mesh on the pier top, so it is necessary to reserve the positions of the manhole on the vibrator and the tumbling barrel where the concrete falls. When the concrete is poured to about 80cm away from the pier top, the uninstalled steel bars will be bound, and the operation time will be shortened as far as possible in the binding process, so as to be completed before the initial setting of concrete. If the existing concrete has been initially set, the joint surface can be roughened manually, and the remaining concrete can be poured after the scum is cleaned up.

(4), template and template installation:

① The piers of this section of viaduct are divided into: combined pier, braking pier, non-braking pier and combined braking pier; According to the section size of the pier, it is divided into1.6m× 2m: 37; 1.8m×2.2m:20； 1.8m×2.4m: 14； 2m×2.6m: 1 1； 2.2m×2.8m:8； 2.4m×3m:3； 2.6m×3m:2； 2.8m×3m:2； 97 construction drawings. According to the size of the tray top cover, it is divided into1.6× 2 ~ 3.8× 4m: 24; 1.8×2 ~ 3.8×4m: 13； 1.8×2.2 ~ 4×4m:20； 1.8×2.4 ~ 4×4.2m: 14； 2×2.6 ~ 4.4×4m: 1 1； 2.2×2.8 ~ 4×4.6m:8； 2.4×3 ~ 4×4.8m: 1； 2.6× 3 ~ 4× 4.8m: 1 The construction drawing has reached 92.

(2) In order to ensure the safety and quality, and meet the requirements of the owner's construction period, the formwork of the elevated pier column in this section adopts centralized processing steel formwork, which has sufficient rigidity and stability, can reliably bear all kinds of loads that may occur during construction, and ensure the accuracy of the shapes and sizes of various parts of the structure. According to the construction drawing, * * * made 14 sets of pier steel formwork.

(3) Before installing the formwork, 4 ~ 6 pieces of iron shall be embedded around the pier formwork to fix the pier formwork at the bottom, anchor wires shall be buried around the foundation pit according to the pier height to fix the pier formwork at the upper part, and supports shall be set for the formwork with pier height greater than 6m to ensure the overall stability of the formwork. Before the formwork installation, the joint surface should be chiseled, the formwork surface should be coated with high-quality release agent, and effective measures should be taken not to pollute the steel bar and concrete construction joints to ensure the smooth and clean surface of the pier. After template installation, check whether the surrounding guy is loose, whether the tie rod is tightened, and whether the adjacent templates are firmly connected. Measure and check the upper and lower openings of formwork with total station to ensure that the deviation of pier formwork is less than 1cm and the verticality meets the requirements.

(4) Construction operation platform: Therefore, the elevated piers at the height of 4 ~ 22m are all working at high altitude, and the operator's operation platform must be set up during construction. The platform and the construction platform are connected into a whole with bowl-shaped scaffolding, and the bowl-shaped scaffolding is set up around the pier. Scaffolding operation platform is used for staff to measure setting out, pouring concrete, check the quality of steel bars, formwork and pouring concrete, and place necessary steel bar welding equipment and concrete pouring vibrating equipment, but formwork and heavy machinery are not allowed to be supported.

(5) The construction operation platform must be separated from the formwork reinforcement bracket, and full-time inspectors shall be set up during the construction to regularly check the changes of the workbench and bracket, and handle the problems in time when found.

(5), concrete pouring:

(1), strictly control the workability of concrete during pouring. After construction, ensure concrete strength, smooth pier appearance and no bubbles. Concrete is poured by concrete pump truck or ground pump. In order to prevent concrete segregation, the pump pipe cannot be inserted. For the pier with concrete falling height greater than 2m, the concrete must be discharged with a string tube. The reinforced concrete of the elevated pier in this section is relatively dense, and the concrete grade is C35, which is relatively high. In order to prevent the water mortar from splashing out and sticking to the upper formwork in the process of concrete formwork falling, and the initial setting is too fast, which will affect the apparent quality after formwork removal, it is necessary to tighten the string tube, and the concrete will enter the formwork for the first time, and the distance between the string tube and the pier bottom shall not be greater than1.5m. When pouring, it will be lifted layer by layer from the lower part, with the horizontal layering thickness of 30cm and the layering thickness of the pier top with dense steel bars of 15cm. When vibrating, two φ 50 internal vibrators are used for vibrating, and two φ 30 internal vibrators are used for vibrating the pier top with dense steel bars. After the vibrator is started, it should be inserted quickly and pulled out slowly until there are no bubbles in the concrete. When the surface is smooth, stop vibrating. When vibrating, the vibrator should be carefully plugged and unplugged according to the operation procedures. The action radius of φ 50 vibrator is 30cm, and it should be plugged and unplugged according to the plum blossom layout according to this distance during operation. The vibrator should avoid colliding with the steel bar and should not be placed on the steel bar. The vibrating rod is about 10cm away from the formwork. It is forbidden to collide with steel formwork. When pouring the upper concrete, the vibrator should be slightly inserted into the lower concrete for about 5 ~ 10 cm, so that the two layers can be integrated. When the construction is 0.8 meters away from the pier top, the embedded reinforcement and shockproof stop should be placed. When pouring to the top surface, it should be trimmed and smoothed as required, and pay attention to the reserved holes of the bearing. When pouring, standby pump should be considered, and hopper should be reserved on site. When the pump fails, the truck crane can be used to lift the hopper to ensure the concrete entering the mold and the continuity of concrete pouring.

(2), pier top cushion stone concrete pouring

Cushion concrete pouring should start 24 hours after pier concrete pouring, and summer-planting reinforcement should be reserved during pier top concrete construction. Before pouring cushion concrete, scum should be chiseled away and holes for installing screws should be reserved. During the construction of cushion stones, it should be noted that the height difference between two cushion stones at the same pier top is not more than 2mm, and the surface flatness of the same cushion stone is not more than 65438 0 mm..

(6), dismantle and concrete curing

(1), according to the Code for Construction of Railway Bridges, when the concrete strength of non-load-bearing members reaches 2.5Mpa, and it can be guaranteed that the surface and edges and corners will not be damaged during formwork removal, the formwork shall be removed. Before form removal, pressure test shall be carried out on the same curing test block. We consider that the formwork is large in size and the pier structure is angular. It is estimated that the form removal period after concrete pouring is 24 ~ 48 hours.

(2) After concrete pouring is completed, it should be cured in time: before formwork removal, the pier top should be covered with geotextile and sprayed with water in time, and the water quality for curing is the same as that for mixing water. For the pier whose bottom is located in the deep foundation pit and exposed to groundwater and running water, before the formwork is removed, the water level in the foundation pit should be controlled by the water pump, and the concrete should not be soaked and washed. After the formwork is dismantled, it shall be wrapped with plastic sheets for maintenance, and attention shall be paid to pouring water down from the pier top at regular intervals.

(7) Backfilling of foundation pit

This section of viaduct adopts cast-in-place prestressed concrete box girder. Backfilling of foundation pit should be compacted by layers, and foundation pit with water should be backfilled with impervious materials. Backfilling shall be carried out after the concrete strength reaches 7d, and the pier shall be filled by manual tamping within 2m.

(8), bearing installation

When installing the bearing, accurately determine the position of each anchor rod on the cushion stone, accurately find the elevation of the top surface of the flat cushion stone, and control the error of absolute elevation and relative elevation within 2mm, and anchor the bearing anchor rod with epoxy mortar. Lift the bearing, aim at each anchor hole, and tighten the anchor bolt to ensure that the height difference around the bearing is not more than 2mm.

Five, quality assurance measures:

1, do a good job in quality pre-control, and do a good job in internal "three inspections" of construction quality (internal self-inspection, inter-shift mutual inspection and internal quality inspection engineer inspection). After passing the "three inspections", report to the supervision engineer for inspection. Only after the supervision engineer has passed the inspection can the construction of the next working procedure be carried out.

2. Conduct technical disclosure before construction, and conduct technical training for relevant personnel before pouring to ensure the quality of concrete pouring.

3. Establish a perfect raw material procurement system, carry out quality inspection and control on incoming materials, and prevent unqualified materials from entering the site.

4. In order to ensure the appearance quality of concrete structure, the formwork of exposed structure should be specially treated. Handle assembly joints properly during construction. Strengthen the control of concrete vibrating process, and arrange experienced vibrators for vibrating.

5, steel processing, according to the requirements of drawings, prefabricated mold, standardized processing and production.

6, grasp the local weather forecast in time during the construction, as far as possible to avoid rainy day construction, in case of rainy day, should be built on the top of the construction operation platform fortification canopy, all construction personnel to prepare rain gear, transport vehicles to prepare rain cloth.

7, equipped with enough personnel, machines and tools, equipment.

8. Concrete construction should comply with the provisions of summer construction: choose cement with low hydration heat, and according to the construction temperature, in addition to the durability index of concrete meeting the requirements of design documents, slow-setting water reducer should be added to appropriately increase slump, and slump loss caused by high temperature should be considered in concrete mix design; The mold temperature of concrete should not be higher than 30℃; Concrete pouring should be carried out at the lower temperature of the day. After pouring is completed, it should be covered and moisturized in time, so as not to form a dry-wet cycle.

9. In case of power failure, the on-site standby generator set should be started immediately to ensure the continuous pouring of concrete.

Six, safety assurance measures:

1, due to the urgent construction period, multi-shift operation will be taken, so it is necessary to establish and improve the mechanical operation responsibility system and the succession system, strengthen management, avoid mistakes and ensure safe production.

2. Strengthen site construction management. Personnel on the construction site must wear safety protection articles such as safety helmets, safety belts for aerial work, and safety nets should be hung on the construction operation platform.

3, each type of work adhere to show certificates. Full-time security officers should track key road sections and night construction.

4. The construction of piers and abutments belongs to aerial work, and the safety technical regulations for aerial work must be observed, and the anti-skid and safety net equipment should be improved.

5, pay attention to the wind in the construction, in case of strong winds of magnitude 6 or above, stop the template installation and removal work, arrange personnel to check the fastening of scaffolding and template reinforcement brackets on the construction platform, and reinforce them in time if they are loose.

6, pay attention to electricity safety, electricity safety education. Full-time electricians are responsible for the arrangement of construction and domestic electricity. Without the consent of electricians, facilities such as power lines or distribution boxes shall not be moved.

7. During the construction of the construction platform, the whole pier construction process, personnel and small tool materials should be considered. When the pier height is less than or equal to 4m, a stable ladder should be set; When the pier is more than 4m high, zigzag spiral ladders must be set, and the steps shall be non-slip and hung with safety nets.