Construction method suitable for water-taking storage tank retention wall of gate shaft tunnel of nuclear power station

Abstract

The invention belongs to the technical field of nuclear power station engineering construction, and particularly relates to a construction method suitable for a nuclear power station gate shaft tunnel water intake storage tank retention wall, which comprises the following steps: step 1, according to the size of a gate shaft tunnel, manufacturing and installing a temporary operation steel platform and an inclined ladder stand; 2, wall body dabbing, drilling and bar planting are carried out on the reinforced concrete retention wall and the bottom face, the front face and the rear face of the gate well concrete, and binding of a reinforcing mesh is carried out on the basis of bar planting; 3, a wall body shaping formwork is manufactured and installed; 4, installing an embedded part, reserving a hole for the retention wall, and pouring concrete into the wall body shaping template; and 5, after the concrete strength meets the requirement, the shaping formwork is dismantled, and after water leakage inspection is qualified, the steel platform and the inclined ladder stand are dismantled. The construction method can be matched with the water emptying time of a power station overhaul gate shaft, and construction of the water-taking storage tank retention wall of the tunnel is completed.

Description

Technical Field

[0001] The invention belongs to the technical field of nuclear power plant engineering construction, and in particular relates to a construction method suitable for a water retaining wall of a gate shaft tunnel water intake storage tank of a nuclear power plant. Background Art

[0002] Many projects in the power plant require fresh water resources, and the municipal water supply cannot meet the demand for fresh water resources for the future development of the power plant. The seawater in the third loop of the nuclear power plant is discharged into the sea through the gate well after heat exchange. The temperature and purity of the seawater source here are good, which can provide seawater for the seawater desalination project of the power plant. During the operation of the nuclear power plant, the circulating water pump remains in operation. At this time, the tunnel flow may be as high as hundreds of thousands of cubic meters per hour, and the flow rate in the tunnel can reach 1.5 to 2 m / s. Due to the overhaul schedule of the power plant, the seawater side gate insertion time is short. The main problem of its civil construction is how to match the time for the overhaul gate well of the power plant to empty the water, install a retaining wall in the gate well, and establish a still water area. Summary of the invention

[0003] The purpose of the present invention is to provide a construction method for a water retaining wall of a gate shaft tunnel water intake storage tank in a nuclear power plant. The method can match the time for draining water from the gate shaft during power plant overhaul and complete the construction of the water retaining wall of the tunnel water intake storage tank, thereby satisfying the civil construction process and not affecting the overhaul period of the power plant.

[0004] The technical solution to achieve the purpose of the present invention is:

[0005] A construction method for a water retaining wall of a gate shaft tunnel of a nuclear power plant, the method comprising:

[0006] Step 1: According to the size of the gate well tunnel, make a temporary working steel platform and an inclined ladder, install the steel platform on the concrete base of the gate well, and install the inclined ladder between the tunnel entrance and the tunnel platform;

[0007] Step 2: Roughen the wall, drill holes and plant reinforcement on the concrete bottom, front and back of the reinforced concrete retaining wall and the gate well, and tie the steel mesh on the basis of the planted reinforcement;

[0008] Step 3: Make a wall template and install it on the gate well concrete base;

[0009] Step 4: Install embedded parts, reserve holes for the retaining wall, and pour concrete into the wall formwork;

[0010] Step 5: After the concrete strength reaches the requirement, remove the wall formwork. After the water leakage inspection is passed, remove the steel platform and inclined ladder.

[0011] The bottom of the steel platform is fixedly connected with supporting legs, and the positions of the supporting legs match the concrete matrix of the gate well to prevent the steel platform from moving horizontally.

[0012] The steel platform is composed of a plurality of rectangular steel plates of the same size spliced ​​along the direction of the gate well concrete matrix. After the steel platform is installed on the gate well concrete matrix, it is integrally connected with flat iron or steel plates.

[0013] The rebar planting method specifically includes: injecting glue into the drill hole, inserting the steel bar into the drill hole after injecting glue, rotating the steel bar in one direction, and inserting while rotating to ensure that the glue and the steel bar are fully bonded.

[0014] The binding of the steel mesh is specifically as follows: prefabricated cement mortar pads are used as a steel bar protection layer, the main bars are tied first and then the distribution bars, the vertical bars of the exterior wall are outside and the horizontal bars are inside, and the interior wall is the opposite, each intersection point of the two rows of steel bars on all sides is tied tightly, the intersection points in the middle part are tied alternately, and all the intersection points of the steel bars of the two-way main bars are tied tightly to complete the binding of the steel mesh.

[0015] The wall forming template comprises: a main keel, a secondary keel, and a wood plywood. The secondary keel is located between the main keel and the wood plywood. The secondary keel is vertically arranged with the main keel. The wood plywood, the secondary keel, and the main keel are fixedly connected in sequence by special glue.

[0016] The main keel is made of channel steel, two channel steels are welded together, the secondary keel is made of wooden square, and the wood plywood is made of 15mm thick plywood.

[0017] When the wall forming templates are installed, the two wall forming templates are arranged opposite to each other, the wood glue boards of the two wall forming templates are adjacent, the tension screws penetrate the two wall forming templates, and the two wall forming templates are connected by the tension screws.

[0018] The outer side of the wall forming formwork is supported by supporting steel pipes, one side is supported horizontally by supporting steel pipes, and the other side is reinforced by supporting steel pipes obliquely.

[0019] The beneficial technical effects of the present invention are:

[0020] 1. The present invention provides a construction method for a water retaining wall of a water intake storage tank in a nuclear power plant gate shaft tunnel. The working steel platform and the wall forming template are prefabricated in advance, and the operation plan of the construction is matched with the drainage / water intake time of the nuclear power plant gate shaft, which does not occupy the extra construction period of the nuclear power plant. Specifically, by using the method of catching the tide construction, during the non-isolation period of the seawater side gate, the platform installation of the storage tank wall, the cleaning of marine organisms, the preliminary work of the wall construction, and the later work such as the removal of the wall forming template, leak detection and repair are completed. The construction period is not restricted by other work and the construction is free. The time requirement for pumping water from the drainage tunnel during the overhaul period of the nuclear power plant is reduced, and the matching of this process with the overhaul progress is improved.

[0021] 2. The present invention provides a construction method suitable for a water retaining wall of a nuclear power plant gate shaft tunnel water intake storage tank. According to the structural characteristics of the nuclear power plant gate shaft, a working steel platform and a process flow of a steel inclined ladder are added, and a special wall forming template reinforcement method is formulated to ensure reliable process quality.

[0022] 3. The present invention provides a construction method for a water retaining wall of a gate shaft tunnel water intake storage tank in a nuclear power plant. The method uses a working steel platform to connect the concrete bases on both sides of the gate shaft water channel, thereby solving the problem of narrow working surface during on-site construction of the gate shaft and improving the safety of construction.

[0023] 4. The present invention provides a construction method suitable for a water retaining wall of a gate shaft tunnel of a nuclear power plant, which uses an operating steel platform as a supporting point for supporting steel pipes, thereby enhancing the supporting strength of the wall forming formwork and improving the quality of concrete pouring. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 This is a top view of the installation of the working steel platform, inclined ladder and retaining wall provided by the present invention;

[0025] Figure 2 A front view of the working steel platform provided by the present invention;

[0026] Figure 3 This is a schematic diagram of the wall forming template skeleton structure provided by the present invention;

[0027] Figure 4 This is a schematic diagram of assembling the wall forming template provided by the present invention;

[0028] Figure 5 This is a schematic diagram of the wall forming formwork support structure provided by the present invention;

[0029] Figure 6 This is a schematic diagram of the reserved holes in the retaining wall provided by the present invention.

[0030] In the figure: 1- retaining wall; 2- steel platform; 3- gate shaft; 4- inclined ladder; 5- main keel; 6- secondary keel; 7- wood plywood; 8- tension screw; 9- wall concrete; 10, scaffolding steel pipe; 11- ground; 12- supporting steel pipe; 13- reserved holes. DETAILED DESCRIPTION

[0031] The present invention is further described in detail below with reference to the accompanying drawings and embodiments.

[0032] The present invention provides a construction method for a water retaining wall of a gate shaft tunnel water intake storage tank in a nuclear power plant, which specifically comprises the following steps:

[0033] Step 1: Make and install temporary steel platform and inclined ladder

[0034] According to the length and width of the upper opening of the gate shaft tunnel, steel platforms of appropriate size and quantity are made, and the steel platforms are fully laid above the tunnel drainage channel. According to the height of the tunnel entrance and the tunnel platform, inclined ladders are made and installed between the tunnel entrance and the tunnel platform for construction personnel to go up and down.

[0035] Lifting and installation: hydraulic truck crane is used for construction, which has high work efficiency and increased safety. The manhole covers above the gate well are lifted out piece by piece, and the manufactured inclined ladder and steel platform are lifted into the gate well and drilled for installation.

[0036] Figure 1 This is a top view of the steel platform. Figure 2 This is the main view of the steel platform. The steel platform is made in a rectangular shape, and a total of 5 pieces are made. The bottom of each steel platform is fixed with a stable support leg, which cooperates with the concrete base of the gate well to prevent the horizontal movement of the steel platform. After the steel platform is installed in place, it is connected as a whole with flat iron or steel plate.

[0037] Step 2: Wall construction

[0038] Wall roughening and reinforcement: Figure 1 , Figure 2 As shown, the concrete bottom surface / front and back surfaces of the reinforced concrete retaining wall and the gate well are roughened and reinforced. The distribution of the original concrete reinforcement is checked with a reinforcement detector. Then, the number and position of reinforcement to be planted are determined by the line. The roughening and drilling are performed according to the number and position of reinforcement to be planted. After the drilling is completed, there will be a lot of residue inside, which directly affects the quality of the reinforcement, so the debris in the hole must be cleaned up. After the above steps are completed, a qualified special glue for rebar planting is selected to inject glue into the drilled hole. The rebar should be planted immediately after the injection. The rebar is inserted into the drilled hole, and the rebar is rotated in one direction while being inserted to ensure that the colloid is fully bonded to the rebar. After the inspection and acceptance of the rebar planting, the pull-out test can be carried out only after the colloid is completely solidified. The non-destructive pull-out test is used for inspection.

[0039] Rebar mesh binding: Rebar mesh binding is carried out on the basis of embedded reinforcement. Prefabricated cement mortar pads are used as a protective layer for the reinforcement. According to the direction of the main reinforcement and distribution reinforcement in the design drawings, the main reinforcement is tied first and then the distribution reinforcement. The vertical reinforcement of the exterior wall is outside and the horizontal reinforcement is inside, while the interior wall is the opposite. The intersection points of the two rows of reinforcements around should be tied tightly at each point, and the intersection points in the middle part can be tied alternately at intervals. For the reinforcement mesh with two-way main reinforcement, all the intersection points of the reinforcement must be tied tightly to complete the binding of the reinforcement mesh.

[0040] Step 3: Make and install the wall template

[0041] The pre-formed template uses a wooden frame with smooth wood glue board 7, a secondary keel 6 as a horizontal beam, and a main keel 5 as a rib. Figure 3-4As shown, the secondary keel 6 is located between the main keel 5 and the wood glue board 7. The secondary keel 6 is arranged vertically with the main keel 5. The smooth wood glue board 7, the secondary keel 6 and the main keel 5 are fixedly connected in sequence by special glue. The main keel 5 is made of channel steel, two channel steels are welded together, the secondary keel 6 is made of wood square, and the wood glue board 7 is made of 15mm thick plywood. A position for the tension screw 8 is reserved in the wood square of the secondary keel 6, and a lifting lug is set. After arriving at the site, it is directly hoisted into the gate plate groove for installation after the steel bar binding is completed. The number of the finalized templates is determined according to the size of the retaining wall, and each finalized template is equipped with 4 pairs of tension screws 8.

[0042] After all the templates are installed in place at the four corners, the templates are balanced and suspended for installation. Figure 4-5 As shown, the assembly sequence of the forming formwork is to first install the prefabricated forming formwork, install the tension screw rods 8, use the tunnel wall and the working steel platform, use the support steel pipes 12 to support the outside of the forming formwork, use the support steel pipes 12 for horizontal support on the east side, and use the support steel pipes 12 for diagonal support reinforcement on the west side, and finally reinforce the tension screw rods 8.

[0043] Step 4: Concrete pouring

[0044] Before pouring concrete, the embedded iron parts are installed first. The embedded iron parts use stainless steel pipes with flange joints on the inside as reserved holes 13 for the water retaining wall. During the use of the water retaining wall, they serve as isolation channels for water inlet and outlet. The schematic diagram of the reserved holes 13 is shown in FIG. Figure 6As shown, it is also convenient for the later blocking and isolation of the gate well after water inflow. Before pouring, the garbage, soil and other debris in the template and the oil stains on the steel bars should be cleaned up, and the cement mortar pads of the steel bars should be checked to see if they are well padded before pouring concrete. When pouring concrete, a chute and a string tube should be used for construction. Before pouring concrete, a 50mm thick stone-free mortar with the same mix ratio should be laid, and then poured in layers. During pouring construction, the pouring time should be strictly controlled to prevent cold joints. When pouring concrete, the formwork, brackets, steel bars, embedded parts and reserved holes should be observed frequently. If deformation or displacement is found, the pouring should be stopped, and reinforcement measures should be taken before the concrete construction can be continued. Concrete pouring should be carried out continuously. When it is necessary to pause, the pause time should be shortened, and the second layer of concrete should be poured before the previous layer of concrete solidifies. During the layered pouring process, the first and second vibrations are carried out. An inserted vibrator is used. The vibrator rod is selected with a diameter of 50mm and a flexible shaft length of 6 to 8m. The thickness of the concrete pouring layer is 1.5 times the length of the effective part of the vibrator. The pouring thickness of the concrete does not exceed 40cm. The moving distance of the vibrator is not greater than 1.5 times its effective radius. When vibrating the concrete, the vibrator rod should be inserted quickly and pulled out slowly until the concrete surface is flooded with slurry and no settlement occurs. Vibrate continuously for 30±5S at each position, depending on the uniform appearance of slurry on the concrete surface. When moving, vibrate in rows and move forward in sequence. The vibrating positions of each vibrator must overlap each other. When vibrating, the formwork must not be vibrated, and collisions with steel bars and embedded parts must be avoided as much as possible. When pouring concrete, use a φ50 vibrator and a crowbar to pry open the steel bars at the intersection of beams and columns and the densely reinforced parts to pour concrete. After the concrete pouring is completed, the steel bars must be reset. Cover and water the concrete within 12 hours after pouring for maintenance.

[0045] Step 5: Dismantling and blind plate sealing

[0046] After the concrete strength of each part meets the requirements, the fixed formwork is removed. The stainless steel flange cover is used to seal the inner side of the stainless steel pipe of the embedded iron parts. After the tunnel is flooded, a water leakage inspection and corresponding solution measures are carried out. After the inspection is qualified, the temporary steel platform and inclined ladder are removed.

[0047] According to the construction experience of a certain nuclear power plant, this process starts from the lifting of the gate manhole cover. It takes 1 working day to erect guardrails and install steel ladders, 2 working days to install the working platform, 2 working days to clean up marine organisms and position and lay out lines, 2 working days to roughen the wall and drill holes for reinforcing bars, 2 working days to tie the steel bars, 2 working days to install and reinforce the formwork, 1 working day to pour concrete, 4 working days to remove the formwork, 1 working day to seal the blind plate, 1 working day to check for leaks, and 1 working day to remove the working platform and temporary ladder.

[0048] The main work progress of the gate well during the nuclear power plant overhaul is as follows: stop the circulating water pump → lower and isolate the seawater side gate → carry out gate well maintenance project → lift the seawater side gate to let water in → start the circulating water pump to drain water. The construction period between lowering and isolating the seawater side gate and lifting and letting water in the seawater side gate during a normal power plant overhaul is about 7 days, which does not meet the construction conditions of all the above processes.

[0049] Tide-catching construction plan arrangement: According to the technical requirements of civil construction, the two tasks of wall roughening, drilling and reinforcing bars, and concrete pouring need to be carried out under drainage and isolation conditions. Therefore, during the 7-day construction period of overhaul gate well isolation, it is necessary to carry out wall roughening, drilling and reinforcing bars, steel bar binding, template installation and reinforcement, and concrete pouring. During the period from the shutdown of the circulating water pump to the lowering of the seawater side gate for isolation, and from the lifting of the seawater side gate to the start of the circulating water pump for drainage, tide-catching construction shall be carried out according to the time when the tunnel water level is lower than the working platform on that day.

[0050] The present invention is described in detail above with reference to the accompanying drawings and embodiments, but the present invention is not limited to the above embodiments, and various changes can be made within the knowledge of ordinary technicians in the field without departing from the purpose of the present invention. The contents not described in detail in the present invention can adopt the existing technology.

Claims

1. A construction method for a water retaining wall of a gate shaft tunnel of a nuclear power plant, characterized in that: The method comprises: Step 1: According to the size of the gate shaft tunnel, a temporary working steel platform (2) and an inclined ladder (4) are manufactured, the steel platform (2) is installed on the gate shaft concrete base, and the inclined ladder (4) is installed between the tunnel entrance and the tunnel platform; Step 2: Roughen the wall, drill holes and plant reinforcement on the concrete bottom, front and back of the reinforced concrete retaining wall and the gate well, and tie the steel mesh on the basis of the planted reinforcement; Step 3: Make a wall template and install it on the gate well concrete base; Step 4: Install embedded parts, reserve holes (13) for the retaining wall, and pour concrete into the wall formwork; Step 5: After the concrete strength reaches the required level, the wall formwork is removed. After the water leakage inspection is passed, the steel platform (2) and the inclined ladder (4) are removed.

2. A construction method for a water retaining wall of a gate shaft tunnel water intake storage tank in a nuclear power plant according to claim 1, characterized in that: The bottom of the steel platform (2) is fixedly connected with a support leg, and the position of the support leg matches the concrete matrix of the gate well to prevent the steel platform (2) from moving horizontally.

3. A construction method for a water retaining wall of a gate shaft tunnel water intake storage tank in a nuclear power plant according to claim 1, characterized in that: The steel platform (2) is composed of a plurality of rectangular steel plates of the same size spliced ​​together along the direction of the gate well concrete base. After the steel platform (2) is installed on the gate well concrete base, it is integrally connected using flat iron or steel plates.

4. A construction method for a water retaining wall of a gate shaft tunnel water intake tank in a nuclear power plant according to claim 1, characterized in that: The rebar planting method specifically includes: injecting glue into the drill hole, inserting the steel bar into the drill hole after injecting glue, rotating the steel bar in one direction, and inserting while rotating to ensure that the glue and the steel bar are fully bonded.

5. The construction method for a water retaining wall of a gate shaft tunnel water intake storage tank in a nuclear power plant according to claim 1, characterized in that: The binding of the steel mesh is specifically as follows: prefabricated cement mortar pads are used as a steel bar protection layer, the main bars are tied first and then the distribution bars, the vertical bars of the exterior wall are outside and the horizontal bars are inside, and the interior wall is the opposite, each intersection point of the two rows of steel bars on all sides is tied tightly, the intersection points in the middle part are tied alternately, and all the intersection points of the steel bars of the two-way main bars are tied tightly to complete the binding of the steel mesh.

6. A construction method for a water retaining wall of a gate shaft tunnel water intake storage tank in a nuclear power plant according to claim 1, characterized in that: The wall forming template comprises: a main keel (5), a secondary keel (6), and a wood glue board (7), wherein the secondary keel (6) is located between the main keel (5) and the wood glue board (7), the secondary keel (6) and the main keel (5) are vertically arranged, and the wood glue board (7), the secondary keel (6), and the main keel (5) are fixedly connected in sequence by special glue.

7. A construction method for a water retaining wall of a gate shaft tunnel water intake storage tank in a nuclear power plant according to claim 6, characterized in that: The main keel (5) is made of channel steel, two channel steels are welded together, the secondary keel (6) is made of wooden square, and the wood glue board (7) is made of 15mm thick plywood.

8. A construction method for a water retaining wall of a gate shaft tunnel water intake storage tank in a nuclear power plant according to claim 6, characterized in that: When the wall forming templates are installed, the two wall forming templates are arranged opposite to each other, the wood glue boards (7) of the two wall forming templates are adjacent, the tension screws (8) pass through the two wall forming templates, and the two wall forming templates are connected by the tension screws (8).

9. A construction method for a water retaining wall of a gate shaft tunnel water intake storage tank in a nuclear power plant according to claim 1, characterized in that: The outer side of the wall forming template is supported by a supporting steel pipe (12), one side is supported horizontally by the supporting steel pipe (12), and the other side is supported obliquely by the supporting steel pipe (12) for reinforcement.

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