A construction method of a big bloom continuous casting machine vortex pool bottom

Abstract

The application relates to a construction method of a large square billet continuous casting machine vortex pool bottom, and belongs to the technical field of large square billet continuous casting machine construction. The technical scheme is: the following steps are performed: step one: a circular pit is dug in the center of the vortex pool bottom; step two: a steel pipe (15) is installed on the circular pit of the vortex pool bottom; step three: a metal frame is welded in the circumferential direction of the steel pipe (15), and 70-180mm-thick pebbles and crushed rocks are filled in the metal frame; step four: a layer of asphalt is hot-poured on a steel plate (16); step five: a blind plate (8) and an upper flange (10) of the steel pipe (15) are fastened and sealed by bolts (6), and then a layer of cement concrete (3) is poured on the asphalt; and step six: a layer of reinforced concrete (2) is poured on the pool bottom cement concrete layer (3). The application has the beneficial effects that the construction efficiency of the large square billet continuous casting machine vortex pool bottom can be improved, the hit rate of the vortex pool bottom construction water sealing can be improved, and the water sealing effect is good.

Description

Technical Field

[0001] This invention relates to a construction method for the bottom of the vortex pool of a large billet continuous casting machine, belonging to the technical field of construction of large billet continuous casting machines in the metallurgical industry. Background Technology

[0002] During the steelmaking process, as molten steel is cast into billets, the secondary cooling water cools the billets and is then discharged into the cyclone pool. The open-circuit water cools the large billet continuous casting equipment and is also discharged into the cyclone pool. Cooling water from the continuous casting machine, after sedimentation and filtration, is pumped to the central pumping station and then returned to the continuous casting machine to cool the billets and equipment. Simultaneously, the slag flushing pump in the cyclone pool also pumps water to flush away the oxide slag under the roller conveyor and cooling bed of the continuous casting machine, and finally, the flushing water also flows into the cyclone pool. Therefore, the cyclone pool is a crucial process facility for large billets. The construction of the cyclone pool generally employs a settling method. After settling to the designated position, the bottom of the cyclone pool is constructed. The purpose of the bottom construction is twofold: firstly, to prevent groundwater from entering the cyclone pool; and secondly, to prevent further settling of the cyclone pool. The bottom construction of the cyclone pool is the most critical step in the construction process. The cyclone pool is relatively deep, and its bottom is below the groundwater level, requiring a groundwater treatment process during construction. There are two methods for groundwater treatment during the construction of the vortex pool bottom:

[0003] 1) Water stop method

[0004] The water-stopping method mainly involves creating a water-stopping curtain around the vortex pool to prevent groundwater from entering the foundation pit. Commonly used water-stopping methods include recharge and diaphragm walls. However, in actual construction, water-stopping methods are relatively expensive and difficult to implement.

[0005] 2) Drainage method

[0006] The drainage method primarily involves removing surface water and groundwater from the vortex pool area. Commonly used drainage methods include wellpoint dewatering. Wellpoint dewatering involves drilling a series of wells around the vortex pool, spaced at intervals, and continuously pumping water to lower the water level at the bottom of the pool. Wellpoint dewatering is suitable for newly constructed vortex pools before the plant building has been built. However, if a vortex pool is being built or expanded within an existing plant building, using wellpoint dewatering to treat groundwater is clearly unreasonable, as it would cause the plant's columns to sink due to the circular well drilling.

[0007] The above two methods for groundwater treatment in vortex pool bottom sealing have significant limitations. They are not suitable for the special hydrogeological conditions, construction environment, technical conditions, vortex pool depth, aquifer permeability, and other conditions in vortex pool construction. If groundwater is not properly treated during vortex pool bottom construction, it will not only affect the construction of the bottom of the vortex pool, but even if the bottom of the vortex pool is completed, groundwater will seep out from the bottom of the vortex pool and infiltrate into the vortex pool, causing construction failure and requiring the bottom of the vortex pool to be destroyed and reconstructed. Summary of the Invention

[0008] The purpose of this invention is to provide a construction method for the bottom of the vortex pool of a large billet continuous casting machine, which can improve the efficiency of the construction of the bottom of the vortex pool and the hit rate of water sealing during the construction of the bottom of the vortex pool. The water sealing effect is good, and groundwater is prevented from gushing out from the bottom of the vortex pool, thus solving the problems existing in the background art.

[0009] The technical solution of this invention is:

[0010] A construction method for the bottom of the cyclone pool in a large billet continuous casting machine, comprising the following steps:

[0011] Step 1: Dig a circular pit in the center of the bottom of the vortex pool, and put the water pump into the circular pit to pump water;

[0012] Step 2: Drill several filter holes in the lower circumference of a steel pipe that matches the diameter of the circular pit. Weld the upper flange to the upper end of the steel pipe and install the steel pipe on the circular pit at the bottom of the cyclone pool. At the same time, move the water pump into the steel pipe to continue pumping water to ensure that the bottom surface of the cyclone pool is dry.

[0013] Step 3: Weld a metal frame around the steel pipe and fill the metal frame with 70-180mm thick pebbles and crushed rocks to form a crushed rock layer at the bottom of the pool.

[0014] Step 4: Weld steel plates onto the metal frame above the gravel layer at the bottom of the pool, and pour a layer of asphalt onto the steel plates.

[0015] Step 5: Remove the water pump from the steel pipe, and tighten and seal the blind flange and the upper flange of the steel pipe with bolts. Then pour a plain concrete layer on the asphalt.

[0016] Step 6: Pour a reinforced concrete layer on the plain concrete layer at the bottom of the pool.

[0017] The upper flange, steel pipe, and blind flange form the central steel cylinder.

[0018] The metal frame includes several circumferential H-beams welded to a steel pipe, annular H-beams welded together with the several circumferential H-beams, and several legs. The metal frame and the central steel cylinder constitute a water sealing platform.

[0019] The diameter of the circular pit at the center of the bottom of the vortex pool matches that of the water pump body.

[0020] The diameter of the circular pit at the center of the bottom of the vortex pool is more than twice the diameter of the pump body, and the depth is more than three times the height of the pump body.

[0021] The thickness of the asphalt on the steel plate is 25-35mm.

[0022] The plain concrete layer has a strength grade of C20 and is poured according to the S8 impermeability grade, and is poured onto the asphalt layer in one go.

[0023] The reinforced concrete layer has a strength grade of C30 and is poured according to the S10 impermeability grade.

[0024] Before pouring the reinforced concrete layer, a steel mesh is first made. When the strength grade of the plain concrete layer reaches more than 30%, the steel bars are tied on it.

[0025] The beneficial effects of this invention are: it can improve the efficiency of construction at the bottom of the vortex pool of the large billet continuous casting machine and the hit rate of water sealing at the bottom of the vortex pool, prevent groundwater from gushing out from the bottom of the vortex pool, and achieve good water sealing effect, strong stability, high reliability and no leakage. Attached Figure Description

[0026] Figure 1 This is a schematic diagram of the groundwater seepage around the vortex pool of the present invention;

[0027] Figure 2 This is a structural diagram of the vortex pool wall of the present invention;

[0028] Figure 3 Top view of the vortex tank sealing platform of the present invention after installation;

[0029] Figure 4 for Figure 3 A-A view;

[0030] Figure 5 This is a cross-sectional view of the vortex pool of the present invention;

[0031] In the diagram: 1. Swirl pool wall; 2. Reinforced concrete layer; 3. Plain concrete layer; 4. Water sealing platform; 5. Crushed stone layer; 6. Bolt; 7. Cutting foot; 8. Blind flange; 9. Central steel cylinder; 10. Upper flange; 11. Circumferential H-beam; 12. Ring H-beam; 13. Support leg; 14. Swirl pool wall gap; 15. Steel pipe; 16. Steel plate. Detailed Implementation

[0032] The invention will be further described below with reference to the accompanying drawings and examples.

[0033] See attached document Figure 2-5 A construction method for the bottom of the cyclone pool in a large billet continuous casting machine, comprising the following steps:

[0034] Step 1: Dig a circular pit in the center of the bottom of the vortex pool, and put the water pump into the circular pit to pump water;

[0035] Step 2: Make several filter holes in the lower circumference of the steel pipe 15 that matches the diameter of the circular pit, weld the upper flange 10 to the upper end of the steel pipe 15, and install the steel pipe 15 on the circular pit at the bottom of the cyclone pool. At the same time, move the water pump into the steel pipe 15 to continue pumping water to ensure the dryness of the bottom surface of the cyclone pool.

[0036] Step 3: Weld a metal frame around the steel pipe 15, and fill the metal frame with 70-180mm thick pebbles and crushed rocks to form the bottom gravel layer 5 of the pool.

[0037] Step 4: Weld steel plate 16 onto the metal frame above the gravel layer 5 at the bottom of the pool, and pour a layer of asphalt onto the steel plate 16.

[0038] Step 5: Remove the water pump from the steel pipe 15, and use bolts 6 to tighten and seal the blind plate 8 and the upper flange 10 of the steel pipe 15. Then pour plain concrete layer 3 on the asphalt.

[0039] Step 6: Pour the reinforced concrete layer 2 on the plain concrete layer 3 at the bottom of the pool.

[0040] In this embodiment, refer to the appendix Figure 2-5 The relevant design parameters of the cyclone pool for this large billet continuous casting machine are as follows: inner diameter 14.5m, outer diameter 16.1m, structural height 21.1m, pool wall thickness 0.8m, and pool wall structure as shown in the attached figure. Figure 2 As shown. The inner and outer walls and bottom slab of the cyclone pool are all made of C30 waterproof concrete with a concrete impermeability grade of P8. The slag pool is made of C30 waterproof concrete with a impermeability grade of P6. Other beams, slabs and foundations are made of C30 concrete, and the cushion concrete is made of C20 plain concrete.

[0041] This construction project utilizes caisson technology, consisting of four sections of pouring and three sinking stages. The first section was poured to a height of 6.1m, the second 6m, and the third 6m. The three sinking stages were as follows: the first 5.8m stage, leaving a 300mm gap above ground; the second 6m stage; and the third 6m stage. ±0.000 corresponds to an absolute elevation of 615.5m. The initial sinking elevation of the cyclone sedimentation tank was -3.3m. The base elevation was -21.1m.

[0042] The method for sealing the bottom of the cyclone pool of the large billet continuous casting machine is to complete the bottom sealing construction of the cyclone pool of the large billet continuous casting machine by using four parts: a crushed stone layer 5 at the bottom of the pool, a sealing platform 4, a plain concrete layer 3, and a reinforced concrete layer 2. The specific steps are as follows:

[0043] (1) Dig a circular pit in the center of the bottom of the vortex pool, put the water pump into the circular pit to pump water until there is no water at the bottom of the vortex pool. Continue to pump water in the circular pit to ensure that the bottom of the vortex pool is dry. Level the soil at the bottom of the vortex pool (except for the circular pit).

[0044] (2) Install and fabricate the water sealing platform 4. The water sealing platform 4 consists of a central steel cylinder 9, eight circumferential H-beams 11, eight annular H-beams 12, several legs 13, several annular steel plates 16, and a blind plate 8. The central steel cylinder 9 includes an upper flange 10, a steel pipe 15, and a blind plate 8. The upper flange 10 is welded to one end of the steel pipe 15. The blind plate 8 is fastened to the upper flange 10 of the steel pipe 15 by bolts 6 after the water sealing platform 4 is fully installed and coated with water sealing asphalt. Several filter holes are machined on the lower circumference of the steel pipe 15. The diameter of the steel pipe 15 should be larger than the circular pit dug at the center of the bottom of the vortex pool without affecting the water pump. The steel pipe 15 is welded to the eight circumferential H-beams 11, and the eight circumferential H-beams 11 are welded to the eight annular H-beams 12 respectively. The eight circumferential H-beams 11 are connected to several legs 13 by welding.

[0045] (3) Before installing the steel plate 16 on the sealing platform 4, fill the metal frame of the sealing platform 4 at the bottom of the vortex pool with 70-180mm pebbles and crushed rocks to form the bottom crushed stone layer 5. The elevation of the bottom of the vortex pool is lower than the groundwater level. The groundwater will overflow the cutting edge 7 under the wall 1 of the vortex pool and emerge from the bottom of the vortex pool. It will pass through the bottom crushed stone layer 5 and enter the central steel cylinder 9. It will be pumped out of the vortex pool. It can be seen that the bottom crushed stone layer 5 plays the role of filtration and support.

[0046] (4) A 3-5mm steel plate 16 is laid on the metal frame (circumferential I-beam 11 and ring I-beam 12) of the bottom sealing platform 4 of the vortex pool. After the steel plate 16 is laid, a 30mm thick layer of asphalt is hot-poured on the steel plate 16. When hot-pouring asphalt on the steel plate 16, special attention should be paid to pouring the gaps between the blade foot 7 of the vortex pool and the bottom sealing platform 4 of the vortex pool, between the steel plates 16 on the bottom sealing platform 4 of the vortex pool, and between the steel plate 16 and the central steel cylinder 9.

[0047] (4) After the asphalt layer on the bottom sealing platform 4 of the vortex pool cools down to normal temperature, the water pump in the central steel cylinder 9 is removed, and the blind plate 8 and the upper flange 10 of the central steel cylinder 9 are tightened and sealed with bolts 6 (with a metal spiral wound gasket between the two flanges). Then, plain concrete layer 3 is poured. The strength grade of the plain concrete layer 3 is C20, and it is poured according to the S8 impermeability grade. It is poured onto the asphalt layer of the bottom sealing platform 4 of the vortex pool in one go.

[0048] (5) The reinforced concrete layer 2 is poured to the position of the pool wall opening 14 of the vortex pool wall 1. Before pouring, a steel mesh is made. When the strength grade of the plain concrete layer 3 at the bottom of the pool reaches more than 30%, the steel bars are tied on it. The reinforced concrete layer 2 at the bottom of the vortex pool is located at the position of the vortex pool wall opening 14 of the vortex pool wall 1. Its main function is to prevent the vortex pool wall 1 from continuing to sink. Therefore, it needs a certain strength. When tying the steel bars at the bottom of the vortex pool, the upper and lower layers use square steel bars in the middle and radial steel bars around the perimeter. After the grouting is completed, a pouring is carried out. The strength grade of the reinforced concrete layer 2 at the bottom of the pool is C30. In order to enhance its seepage prevention performance, it is poured according to the S10 seepage prevention grade. It is poured into the asphalt layer of the sealing platform 4 at the bottom of the vortex pool in one go. After observing for 24 hours without leakage, the strength of the reinforced concrete layer 2 at the bottom of the vortex pool reaches 100%, and the sealing of the bottom of the vortex pool is completed.

Claims

1. A construction method for the bottom of the vortex tank of a large billet continuous casting machine, characterized in that: Follow these steps: Step 1: Dig a circular pit in the center of the bottom of the vortex pool, and put the water pump into the circular pit to pump water; Step 2: Make several filter holes in the lower circumferential direction of the steel pipe (15) that matches the diameter of the circular pit. Weld the upper end of the steel pipe (15) to the upper flange (10) and install the steel pipe (15) on the circular pit at the bottom of the vortex pool. At the same time, move the water pump into the steel pipe (15) to continue pumping water to ensure the dryness of the bottom plane of the vortex pool. Step 3: Weld a metal frame around the steel pipe (15) and fill the metal frame with 70-180mm thick pebbles and crushed rocks to form a crushed rock layer (5) at the bottom of the pool. Step 4: Weld a steel plate (16) onto the metal frame above the gravel layer (5) at the bottom of the pool, and pour a layer of asphalt onto the steel plate (16); Step 5: Remove the water pump from the steel pipe (15), and use bolts (6) to tighten and seal the blind plate (8) and the upper flange (10) of the steel pipe (15), and then pour plain concrete layer (3) on the asphalt. Step 6: Pour a reinforced concrete layer (2) on the plain concrete layer (3) at the bottom of the pool.

2. The construction method for the bottom of the vortex pool of a large billet continuous casting machine according to claim 1, characterized in that: The upper flange (10), steel pipe (15) and blind flange (8) form the central steel cylinder (9).

3. The construction method for the bottom of the vortex pool of a large billet continuous casting machine according to claim 1, characterized in that: The metal frame includes several circumferential I-beams (11) welded to the steel pipe (15) and annular I-beams (12) welded together with the several circumferential I-beams (11), as well as several legs (13). The metal frame and the central steel cylinder (9) constitute a water sealing platform (4).

4. The construction method for the bottom of the cyclone pool of a large billet continuous casting machine according to claim 1, characterized in that: The diameter of the circular pit at the center of the bottom of the vortex pool matches that of the water pump body.

5. The construction method for the bottom of the vortex pool of a large billet continuous casting machine according to claim 4, characterized in that: The diameter of the circular pit at the center of the bottom of the vortex pool is more than twice the diameter of the pump body, and the depth is more than three times the height of the pump body.

6. The construction method for the bottom of the vortex pool of a large billet continuous casting machine according to claim 1, characterized in that: The thickness of the asphalt on the steel plate (16) is 25-35 mm.

7. The construction method for the bottom of the vortex pool of a large billet continuous casting machine according to claim 1, characterized in that: The plain concrete layer (3) has a strength grade of C20 and is poured according to the S8 impermeability grade, and is poured onto the asphalt layer in one go.

8. The construction method for the bottom of the vortex pool of a large billet continuous casting machine according to claim 1, characterized in that: The reinforced concrete layer (2) has a strength grade of C30 and is poured according to the S10 impermeability grade.

9. The construction method for the bottom of the vortex pool of a large billet continuous casting machine according to claim 1, characterized in that: Before pouring, a steel mesh is made for the reinforced concrete layer (2). When the strength grade of the plain concrete layer (3) reaches more than 30%, steel bars are tied on it.

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