A construction method for combining spiral casing with concrete and surrounding structure under stress

Abstract

The present invention provides a construction method for a volute outer concrete and a surrounding structure to be jointly stressed, comprising the following steps: ① pre-fixing: anchoring the volute top plate steel bars into the pre-cast structure; ② pre-casting: casting the pre-cast structure based on the casting template, and curing for many days to reach the design strength; ③ removing the template: removing the casting template, and roughening the new and old concrete joints formed in the pre-cast structure during the casting process; ④ installing the volute: installing the metal volute and burying the electromechanical equipment, and tying the volute steel bars on the metal volute; ⑤ welding: welding the volute top plate steel bars with the pre-fixed exposed steel bars, changing the force transmission mechanism of the volute top plate, thereby canceling the steel bar arrangement of the volute outer concrete side wall; ⑥ post-casting the volute outer concrete. The present invention can reduce the processing, installation and use of steel bars, simplify the construction process, reduce cross-operation, speed up the construction progress, save project investment, and save energy and protect the environment.

Description

Technical Field

[0001] The invention relates to a construction method for a volute outer casing wrapped with concrete and subjected to joint stress with a surrounding structure, belonging to the technical field of water conservancy, hydropower and electric power engineering application. Background Art

[0002] In power stations with high and medium water heads, metal volutes are mostly used. The internal water pressure of this type of volute is borne by the metal volute itself. The upper half of the volute is separated from the outer concrete by an elastic cushion layer, so that the load transmitted from the upper structure of the volute (mainly the pier) is completely borne by the outer concrete of the volute. Due to the complex shape of the volute, the surrounding concrete is an irregular space block structure. In the design, several unit width sections are often cut radially along the center line of the volute, and the calculation is performed according to the plane г-frame. In the calculation, it is assumed that the top plate of the г-frame is hinged on the turbine seat ring, and the bottom end of the side wall is fixed on the large volume concrete at the bottom of the volute. The inner and outer layers of steel bars of the volute outer concrete are configured according to the internal force calculation results of the г-frame. According to the construction organization and schedule of the power station, the first-phase concrete of the upstream and downstream of the plant and the surrounding walls is generally constructed first to form an enclosed structure, and the second-phase concrete of the volute outer casing is constructed in the surrounding first-phase concrete structure that has been poured. Due to the dense steel bars inside and outside the volute, the concentrated layout of electromechanical pipelines, the limited construction site, the large number of special-shaped steel bars welded on site, the long construction period, and the difficulties of cross-operation of a large number of civil engineering and electromechanical installation in the reinforced concrete construction. Therefore, how to simplify the reinforcement form around the volute and reduce the amount of steel bars used is an urgent problem to be solved in the project. Summary of the invention

[0003] In order to solve the above technical problems, the present invention provides a construction method for jointly bearing stress between the outer casing concrete and the surrounding structure. The outer casing concrete and the surrounding structure are constructed by anchoring the steel bars of the top plate of the volute into the pre-cast concrete of the surrounding area, and through measures such as seam surface treatment, the pre-cast concrete and the outer casing concrete form an integral stress-bearing structure, simplifying the calculation model of the outer casing concrete structure, and eliminating the reinforcement at the junction of the outer casing concrete and the pre-cast concrete, thereby achieving the purpose of reducing the use of steel bars, speeding up the construction progress, reducing project investment, and simplifying the construction process.

[0004] The present invention is achieved through the following technical solutions.

[0005] The present invention provides a construction method for a spiral casing wrapped with concrete and subjected to joint stress with a surrounding structure, comprising the following steps:

[0006] ① Pre-fixation: Divide the spiral case top plate steel bar into two parts, and anchor the pre-fixed end into the pre-cast structure;

[0007] ② Pre-casting: Pre-cast the structure based on the casting formwork, and then cure it for several days to reach the designed strength;

[0008] ③Remove the formwork: remove the casting formwork and roughen the joints between the new and old concrete formed during the casting process of the first casting structure;

[0009] ④Install the volute: install the metal volute and bury the electromechanical equipment, and tie the remaining steel bars of the volute top plate on the metal volute;

[0010] ⑤ Welding: Weld the spiral case top plate steel bars to the pre-fixed exposed steel bars;

[0011] ⑥ Post-casting: Cast the volute outer casing concrete outside the metal volute, and after several days of curing to reach the design strength, carry out subsequent installation construction above the volute top plate.

[0012] The pre-cast structure is the concrete outer covering of the perimeter wall of the plant or the volute of the adjacent unit section.

[0013] When the pre-cast structure is the perimeter wall of the factory building, in step ①, the pre-cast concrete reinforcement is first tied along the perimeter wall of the factory building, and at the same time, the spiral case top plate reinforcement is anchored into the pre-cast structure according to the reinforcement anchorage length.

[0014] When the first cast structure is the volute outer concrete of the adjacent unit section, in step ①, the volute top plate steel bars are stretched and arranged and anchored into the volute outer concrete of the adjacent unit section, the exposed length of the volute top plate steel bars is greater than the anchoring length, and the joints are staggered.

[0015] The plurality of days is 28 days.

[0016] The exposed steel bars in step ⑤ are the exposed parts of the pre-fixed sections of the spiral top plate steel bars anchored in the pre-cast structure.

[0017] In the step ②, before the formwork is erected for casting, holes are firstly punched on the casting formwork and seam surface dowel bars are arranged.

[0018] The beneficial effects of the present invention are as follows: when pouring the outer casing concrete, the surrounding pre-cast concrete structure can be used as a template without setting up a separate template; the stress-bearing steel bars of the volute top plate are anchored into the pre-cast concrete to change its force transmission mechanism, so that the stress of the top plate is transmitted to the surrounding large-volume concrete in advance, so as to prevent the stress of the outer casing concrete from increasing and the metal volute from deforming, which will affect the power generation power and structural safety; after the outer casing concrete and the surrounding walls form an integral structure, the steel bars of the side walls of the outer casing concrete at the joint can be cancelled; after the outer casing concrete of adjacent units forms an integral structure, the steel bars of the side walls of the outer casing concrete at the joint of the two units can be cancelled at the same time, thus killing two birds with one stone; the processing, installation and use of steel bars can be reduced, the construction process can be simplified, cross-operation can be reduced, the construction progress can be accelerated, the project investment can be saved, and energy conservation and environmental protection can be achieved. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 It is a schematic diagram of the structure of the present invention when the first cast structure is the perimeter wall of the factory building;

[0020] Figure 2 It is a structural schematic diagram of the present invention when the first cast structure is the outer concrete of the volute of the adjacent unit section.

[0021] In the figure: 1-the perimeter wall of the factory building, 2-the outer concrete of the volute, 3-the metal volute, 4-the lining of the machine pit, 5-the machine pier, 6-the top plate of the volute, 7-the steel bars of the top plate of the volute, 8-the steel bars of the concrete poured first, 9-the joint between the new and old concrete, 10-the steel bars of the volute. DETAILED DESCRIPTION

[0022] The technical solution of the present invention is further described below, but the scope of protection claimed is not limited to the description.

[0023] The invention discloses a construction method for a spiral casing outer casing wrapped with concrete and a surrounding structure to be subjected to joint force, wherein the construction structure is as follows: Figure 1 , Figure 2 As shown, it includes the following steps:

[0024] ① Pre-fixation: Split the spiral case top plate steel bar 7 into two parts, and anchor the pre-fixed end into the pre-cast structure;

[0025] When the structure to be cast first is the perimeter wall 1 of the plant, first tie the pre-cast concrete reinforcement 8, and at the same time anchor the spiral case top plate reinforcement 7 into the pre-cast structure according to the reinforcement anchorage length;

[0026] When the structure poured first is the adjacent unit section volute outer concrete 2, the adjacent unit volute installation inspection is completed, the volute top plate steel bars 7 are pulled through and arranged, and anchored into the previously poured volute outer concrete 2. The exposed steel bar anchorage length of the volute top plate steel bars 7 is convenient for welding with the later poured volute outer concrete steel bars. The exposed length of the volute top plate steel bars 7 is greater than the anchorage length, and the welding joints are staggered.

[0027] ② Casting first: Punch holes in the formwork to set up seam reinforcement, and cast the surrounding walls of the plant 1 or the outer casing of the adjacent unit section with concrete 2. After 28 days of curing, the design strength is achieved.

[0028] ③ Removal of formwork: After removing the formwork of the plant surrounding wall 1 or the outer concrete 2 of the volute of the adjacent unit section, roughen the joint surface 9 between the new and old concrete.

[0029] ④ Install the volute: install the volute of the post-cast concrete and bury the related electromechanical equipment, and at the same time tie the remaining sections of the volute top plate steel bars 7 on the metal volute 3.

[0030] ⑤ Welding: Weld the remaining section of the spiral case top plate steel bar 7 to the pre-fixed exposed steel bar anchored in the first cast structure.

[0031] ⑥ Post-casting: After the conditions for pouring concrete are met, pour the volute outer concrete 2, and after 28 days of curing to reach the design strength, continue the installation construction above the volute top plate 6, specifically, including the installation construction of the pit lining 4 and the machine pier 5.

[0032] Through the above steps, the first pouring of concrete around the volute outer concrete and the later pouring of concrete form an integral structure, achieving the purpose of eliminating the steel bars of the volute outer concrete side wall. Based on a large amount of engineering experience, this method is reliable and easy to implement, and has promotion value.

Claims

1. A construction method in which the spiral casing is wrapped with concrete and the surrounding structure is subjected to joint force, characterized in that: The following steps are included: ① Pre-fixation: Split the spiral case top plate steel bar (7) into two and anchor the pre-fixed end into the pre-cast structure; ② Pre-casting: Pre-cast the structure based on the casting formwork, and then cure it for several days to reach the designed strength; ③ Removing the formwork: removing the casting formwork, and roughening the new and old concrete joints (9) formed during the casting process of the first casting structure; ④ Installing the volute: installing the metal volute (3) and burying the electromechanical equipment, and at the same time tying the remaining section of the volute top plate steel bars (7) on the metal volute (3); ⑤ Welding: welding the remaining section of the spiral case top plate steel bar (7) to the pre-fixed exposed steel bar anchored in the pre-cast structure; ⑥ Post-casting: Cast the volute outer casing concrete (2) outside the metal volute (3), and after curing for many days to reach the designed strength, the subsequent installation construction above the volute top plate (6) is carried out.

2. The construction method of the spiral casing outer concrete and the surrounding structure being jointly stressed as claimed in claim 1, characterized in that: The pre-cast structure is the perimeter wall (1) of the plant or the outer casing concrete (2) of the adjacent unit section.

3. The construction method of the spiral casing outer concrete and the surrounding structure being jointly stressed as claimed in claim 2, characterized in that: When the pre-cast structure is the perimeter wall (1) of the factory building, in step ①, the pre-cast concrete reinforcement (8) is first tied along the perimeter wall (1) of the factory building, and at the same time, the spiral case top plate reinforcement (7) is anchored into the pre-cast structure according to the reinforcement anchorage length.

4. The construction method of the spiral casing outer concrete and the surrounding structure being jointly stressed as claimed in claim 2, characterized in that: When the structure to be cast first is the volute outer casing concrete (2) of the adjacent unit section, in step ①, the volute top plate steel bars (7) are stretched and arranged and anchored into the volute outer casing concrete (2) of the adjacent unit section, the exposed length of the volute top plate steel bars (7) is greater than the anchoring length, and the joints are arranged in a staggered manner.

5. The construction method of the spiral casing outer concrete and the surrounding structure being jointly stressed as claimed in claim 1, characterized in that: The plurality of days is 28 days.

6. The construction method of the spiral casing outer concrete and the surrounding structure being jointly stressed as claimed in claim 1, characterized in that: The exposed steel bars in step ⑤ are the exposed parts of the pre-fixed sections of the spiral top plate steel bars (7) anchored in the pre-cast structure.

7. The construction method of the spiral casing outer concrete and the surrounding structure being jointly stressed as claimed in claim 1, characterized in that: In the step ②, before the formwork is erected for casting, holes are firstly punched on the casting formwork and seam surface dowel bars are arranged.

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