Reverse construction method for cooling tower circulating water frame

Abstract

This invention discloses a reverse-sequence construction method for the circulating water frame of a cooling tower. The suction tank and the cooling tower's collection tank are enclosed reinforced concrete tanks at different elevations, partially intersecting with each other. A post-cast expansion reinforcement strip is left at the mid-span of the shared wall location, dividing the collection tank into two parts for construction. Construction begins with the bottom slab, beams, columns, and walls of the collection tank on the side where it does not intersect with the suction tank, simultaneously with the walls of the suction tank. Next, the bottom slab of the collection tank on the side where it intersects with the suction tank is constructed, poured simultaneously with the walls of the suction tank. Finally, the top slab of the suction tank and the columns and beams on the side where the collection tank intersects with the suction tank are constructed. This construction method facilitates construction organization and allows for the simultaneous construction of the collection and suction tanks, resulting in a reasonable and compact construction period and overall cost savings.

Description

Technical Field

[0001] This invention relates to a construction method for an integrated circulating water tank, and more specifically, to a method for segmented reverse construction of a cooling tower circulating water frame. Background Technology

[0002] The interconnected circulating water tank consists of an underground intake tank and an above-ground cooling tower collection tank. The traditional construction process involves constructing the underground tank first, followed by the above-ground tank. For example, in the integrated refining and chemical project of Shenghong Refining & Chemical (Lianyungang) Co., Ltd., undertaken by China National Chemical Engineering Second Construction Group Co., Ltd., the intake tanks of the No. 1 / 2 refining circulating water field and the cooling tower collection tank are connected as one unit at a height of 6.4m to 8.2m. They are closed reinforced concrete water tanks at different elevations, with the intake tank measuring 138.5*11.0m (partially 79.40*4.0m).

[0003] Because there are usually roads and buildings in use around the foundation pit, the site is limited and the construction difficulty is increased. In order to facilitate construction organization and the cross-construction of the water collection tank and the water intake tank, it is necessary to improve the traditional construction method. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to provide a reverse construction method for the cooling tower circulating water frame, so as to facilitate cross-construction and improve the overall construction efficiency.

[0005] To solve the above technical problems, the technical solution adopted by the present invention is as follows: A reverse-order construction method for the circulating water frame of a cooling tower, wherein the water intake tank and the water collection tank of the cooling tower are closed reinforced concrete water tanks at different elevations and partially intersect with shared walls, includes the following steps: Step 1: Construct the cooling tower pile foundation. Step 2: After the excavation of the water intake pool, the foundation cushion and pile core are constructed, followed by the construction of the reinforced concrete formwork for the bottom slab of the water intake pool. After the construction is completed, the waler support of the water intake pool is removed. Step 3: Leave a post-cast expansion reinforcement strip at the mid-span of the common wall location to divide the water collection tank into two parts for construction: the side where the water collection tank and the water intake tank do not intersect and the side where the water collection tank and the water intake tank intersect. Step 4: Construct the bottom slab of the water collection tank on the side where the water collection tank and the water intake tank do not intersect, and at the same time construct the tank wall of the water intake tank. Step 5: Construct the beams, columns, and walls of the water collection tank on the side where the water collection tank and the water intake tank do not intersect, and simultaneously construct the walls of the water intake tank. Step 6: Construct the bottom slab of the water collection tank on the side where the water collection tank intersects with the water intake tank, and pour it at the same time as the wall of the water intake tank; Step 7: Construct the top slab of the water intake pool and the columns and beams on the side where the water collection pool intersects with the water intake pool.

[0006] Furthermore, in step two, before the excavation of the water intake pool, the water intake pool foundation pit is supported by a retaining system of steel sheet piles and steel bracing.

[0007] Furthermore, in step two, after the excavation of the water intake pool, the secondary slope of the water intake pool is reinforced with 50mm thick reinforced concrete.

[0008] Furthermore, in step three, the concrete inside the expansion reinforcement strip is separated from the concrete outside the strip by double-layer dense wire mesh on both sides. A water-stop steel plate is arranged along the entire length of the bottom plate of the water collection pool at the expansion reinforcement strip to cut off the water seepage path at the construction joint between the old and new concrete at the expansion reinforcement strip.

[0009] Furthermore, in step three, after the concrete is poured on both sides of the bottom slab of the water collection tank for 28 days, a post-cast expansion reinforcement strip is poured.

[0010] Furthermore, in step three, the amount of cementitious material used in the shrinkage-compensating concrete on both sides of the expansion reinforcement strip is ≥340kg / m³.

[0011] Furthermore, in step three, the amount of cementitious material used in the shrinkage-compensating concrete within the expansion reinforcement strip is ≥360kg / m³, and the water-cement ratio is ≤0.40.

[0012] Furthermore, in steps four, five, and six, the pouring sequence of the water intake tank wall is to pour it evenly and symmetrically in layers along the base plate, with each layer not exceeding 300mm in height.

[0013] According to the technical solution provided by the present invention, the cooling tower water collection tank is divided into two parts by using a post-cast expansion reinforcement strip. One part is constructed normally with flowing water, while the other part is constructed simultaneously with the water intake tank. The construction method facilitates construction organization and the cross-construction of the water collection tank and the water intake tank. The construction period is reasonably and compactly controlled, which saves construction costs, reduces construction risks, ensures construction quality, and achieves good economic and social benefits. Attached Figure Description

[0014] The accompanying drawings, which are provided to further illustrate the invention and form part of this application, illustrate exemplary embodiments of the invention and are used to explain the invention, but do not constitute an undue limitation of the invention.

[0015] Figure 1 This is a construction flowchart of the reverse construction method for the cooling tower circulating water frame described in this invention; Figure 2 This shows the location of the post-cast expansion reinforcement strip in the oil refining circulating water field in an embodiment of the present invention; Figure 3 The construction of the cooling tower AD axis is completed. At the same time, the pool wall at -2.3m of the water intake pool is under construction, and temporary scaffolding is erected at the DE axis. Figure 4 The construction of the 7.9m column and beam at the AD axis of the cooling tower has been completed, and the bottom of the 3.000m water intake pool has also been constructed. Figure 5 The construction of the 10.8m column and beam at the AD axis of the cooling tower was completed. At the same time, the construction of the water intake pool wall below 6.4m and the bottom plate of the water collection pool at the E axis were carried out. The temporary scaffolding at the DE axis of the cooling tower was also dismantled. Figure 6 The construction of the water intake tank top slab, as well as the E-axis column and beam, is shown, with construction proceeding upwards in sequence.

[0016] In the diagram, point a is the location where the additional post-cast expansion reinforcement strip is placed, and point b is the location where the post-cast expansion reinforcement strip is moved. 1-The bottom slab of the collection tank along axis AD; 2-The wall of the suction tank at -2.3m; 3-The column and beam at axis AD at 7.9m; 4-The bottom of the suction tank at 3.000m; 5-The column and beam at axis AD at 10.8m; 6-The wall of the suction tank below 6.4m; 7-The bottom slab of the collection tank along axis E; 8-The temporary scaffolding along axis DE; 9-The top slab of the suction tank; 10-The column and beam along axis E. Detailed Implementation

[0017] To enable those skilled in the art to better understand the present invention, the present invention will be further described clearly and completely below with reference to the accompanying drawings and embodiments. It should be noted that, unless otherwise specified, the embodiments and features in the embodiments of this application can be combined with each other.

[0018] A typical embodiment of the present invention provides a construction method for a large-scale interconnected circulating water tank, mainly involving a reverse construction method for the circulating water frame of a cooling tower. The water intake tank and the water collection tank of the cooling tower are closed reinforced concrete water tanks at different elevations and partially intersect with each other. In view of its characteristics, the present invention breaks with the traditional construction plan and adjusts the construction sequence according to the actual site conditions, changing the original principle of underground first and above ground first to constructing the above ground tank first and then the underground tank.

[0019] like Figure 1 As shown, the reverse construction method for the cooling tower circulating water frame provided by the present invention includes the following steps.

[0020] Step 1: Construct the cooling tower pile foundation.

[0021] After the cooling tower is surveyed and marked out, the earthwork for the cooling tower is excavated, followed by the construction of the cooling tower foundation reinforcement, formwork and concrete. After the construction is completed, the earthwork is backfilled.

[0022] Step two: After the excavation of the water intake pool, the foundation pad and pile core are constructed, followed by the construction of the reinforced concrete formwork for the bottom slab of the water intake pool. After the construction is completed, the waler supports of the water intake pool are removed.

[0023] The displacement of the slope during the excavation of the water intake pool foundation pit meets the specifications, and no safety accidents such as collapse or landslide occur. The foundation of the cooling tower, which is adjacent to the water intake pool foundation pit and has been constructed, has no large horizontal displacement, and the settlement meets the specifications.

[0024] After the excavation of the suction tank foundation pit is completed, the net dimensions of the pit bottom should meet the requirements of the foundation construction. The excavation of the foundation pit should follow a layered, segmented, and sequential approach. The construction should be organized according to the principles of "large foundation pit, small excavation, breaking down the whole into parts, segmented excavation, and layered excavation, starting with the deepest parts and progressing to the shallowest." Before excavation, proper water containment and interception measures should be implemented outside the pit, and drainage ditches should be constructed inside the pit for collection and drainage.

[0025] The water intake pool foundation pit adopts a retaining system of steel sheet piles and steel supports. The secondary slope is protected by 50mm thick reinforced concrete, which effectively reduces the load on the deep foundation pit of the water intake pool from the adjacent completed cooling tower foundation and solves the construction problems caused by reverse construction.

[0026] Because the suction tank foundation pit is adjacent to the cooling tower foundation and cannot be excavated with a continuous slope, a 0.9m slope excavation was first carried out, followed by the construction of a 0.5m wide tiered platform for reinforced concrete slope protection. Sheet pile positions were marked, and sheet pile installation began. Then, the upper layer of soil above the upper walers was excavated and removed. The next layer of excavation was carried out only after the walers steel supports were installed, leaving a 200-300mm margin for manual removal at the foundation bottom. When the suction tank foundation pit excavation reached the foundation bottom elevation, manual cleaning was carried out, and the concrete cushion layer had to be poured within 24 hours. The cushion layer extended to the edge of the support structure to facilitate foundation work within the pit and to some extent prevent pit bottom heave. The concrete bottom slab and cushion layer of the suction tank were poured to the edge of the sheet piles to facilitate the removal of supports during the construction of the suction tank walls. The slope treatment of the foundation trench fully considered the site and geological characteristics of this project, adhering to the principles of safety and economy. The water intake tank foundation pit is excavated to the steel sheet pile working surface with a slope ratio of 1:1.5, with a platform of 500mm and a working surface of 0.8m. The slope protection of the foundation pit is made of 50mm thick C20 plain concrete with bidirectional steel reinforcement of φ4@150mm.

[0027] Step 3, as Figure 2 As shown, a post-cast expansion reinforcement strip is left at the mid-span of the common wall location to divide the water collection pool into two parts for construction: the side where the water collection pool and the water intake pool do not intersect and the side where the water collection pool and the water intake pool intersect.

[0028] The cooling tower collection tank and suction tank of the No. 1 / 2 refinery circulating water field are connected as one unit. Combining the structural forms of the two tanks, a post-cast expansion reinforcement strip is added at the common wall section along the long side of the bottom plate of the collection tank. Figure 2 (at point a) and the post-cast expansion reinforcement strip in the width direction of the bottom slab of the water collection tank in the existing drawings ( Figure 2At point b), the water collection pool is divided into two construction sections at the point where the water collection pool and the water intake pool share a common wall and at the post-cast expansion reinforcement zone. One section is constructed normally with continuous water flow, while the other section is constructed simultaneously with the water intake pool.

[0029] Post-cast expansion reinforcement strips are installed at locations of lower structural stress, typically at one-third of the span of beams and slabs. The strip should be 2 meters wide, and fine-mesh wire mesh should be used on both sides to separate the concrete inside and outside the strip. The concrete grade inside the expansion reinforcement strip should be one grade higher than that outside. A water-stop steel plate is installed along the entire length of the bottom slab of the sump at the expansion reinforcement strip location to cut off the water seepage path at the construction joint between the old and new concrete.

[0030] The reinforcement at the post-cast expansion joint should be consistent with the reinforcement in the drawings. The beam and slab reinforcement at the post-cast expansion joint should not be cut off, and additional reinforcement should be added. The pool wall reinforcement must be independently positioned and reinforced in advance according to the drawings, ensuring the axis elevation is correct, horizontally and vertically aligned, and strictly prohibiting reliance on formwork. Larger openings and embedded sleeves in the pool wall should be pre-defined according to the design position during material preparation; no cutting or binding is allowed, and openings must not be made by welding after all binding is completed. The concrete cover for the reinforcement must be constructed according to the drawings and specifications. Reinforcement supports, struts, etc., must not use round steel and must not penetrate the entire concrete section of the pool wall or bottom.

[0031] The post-cast expansion reinforcement strip should be poured 28 days after the concrete on both sides. This solves the problems of concrete shrinkage and temperature changes in a large-span pool and facilitates continuous construction. The amount of cementitious material in the shrinkage-compensating concrete on both sides of the expansion reinforcement strip should be ≥340kg / m³, and the amount of cementitious material in the shrinkage-compensating concrete inside the expansion reinforcement strip should be ≥360kg / m³, with a water-cement ratio ≤0.40.

[0032] Pool wall pouring sequence: Pour concrete evenly and symmetrically in layers along the base slab, with each layer not exceeding 300mm in height. During pool pouring, in addition to pre-designed construction joints, sufficient concrete pump trucks must be available according to the actual site conditions to ensure timely concrete pouring and to ensure continuous pouring of the upper layer of concrete before the lower layer initially sets. Construction joint treatment: Steel plate waterstop joints should be lapped, with an overlap length of not less than 30mm; all joints should be fully welded on both sides.

[0033] Before constructing the expansion joint reinforcement, roughen and clean both sides of the concrete and rinse them with water. The initial concrete pour should have a strength of 1.2 MPa. Before continuing to pour concrete on the hardened concrete surface, remove debris, cement slurry, loose sand and gravel, and weak concrete layers. Roughen the surface, rinse thoroughly with water, and ensure it is fully moistened, but avoid water accumulation. When bending back reinforcing bars near construction joints, ensure the surrounding concrete is not loosened or damaged. Remove oil, cement mortar, rust, and other debris from the reinforcing bars. Use lapped joints for the reinforcing bars as specified. Before pouring, a 10-15 mm thick layer of cement mortar should be laid over the horizontal construction joint, with the same mix proportion as the mortar in the concrete.

[0034] In this embodiment, the AD axis of the cooling tower is the side where the water collection tank and the water intake tank do not intersect, and the DE axis of the cooling tower is the side where the water collection tank and the water intake tank intersect.

[0035] To facilitate the construction of columns and beams above 6.4m on the AD axis of the cooling tower and to speed up the construction progress of the cooling tower, temporary scaffolding will be erected on the DE axis of the cooling tower. Once the beams and columns at 10.8m of the cooling tower and the water intake pool are poured, the temporary scaffolding will be dismantled and the construction of the cooling tower will proceed in a unified manner.

[0036] Step four, as Figure 3 As shown, the bottom slab 1 of the water collection tank along the AD axis of the cooling tower is constructed first, and the pool wall 2 at -2.3m of the suction pool is constructed simultaneously. Temporary scaffolding 8 is erected at the DE axis. The temporary scaffolding uses 18mm channel steel as the base, with the channel steel being 3000mm long and spaced 1500mm apart.

[0037] Step 5, as Figure 4 As shown, the construction of the 7.9m column, beam 3, and pool wall at the AD axis of the cooling tower was completed, and the bottom 4 and pool wall of the 3.000m water intake pool were constructed at the same time.

[0038] Step six, as follows Figure 5 As shown, the construction of the 10.8m column and beam 5 at the AD axis of the cooling tower was completed. At the same time, the construction of the water absorption pool wall 6 below 6.4m and the bottom plate 7 of the water collection pool at the E axis was completed, and the temporary scaffolding 8 at the DE axis of the cooling tower was dismantled.

[0039] Step seven, as Figure 6 As shown, the construction of the top slab 9 of the water intake pool, and the column and beam 10 of axis E are carried out sequentially upwards.

[0040] The scope of protection claimed by this invention is not limited to the specific embodiments described above. For those skilled in the art, this invention can have various modifications and alterations. Any modifications, improvements, and equivalent substitutions made within the concept and principles of this invention should be included within the scope of protection of this invention.

Claims

1. A method for reverse construction of a cooling tower circulating water frame, wherein the water intake tank and the cooling tower collection tank are closed reinforced concrete water tanks at different elevations and partially intersect with a shared wall, characterized in that... Includes the following steps: Step 1: Construct the cooling tower pile foundation. Step 2: After the excavation of the water intake pool, the foundation cushion and pile core are constructed, followed by the construction of the reinforced concrete formwork for the bottom slab of the water intake pool. After the construction is completed, the waler support of the water intake pool is removed. Step 3: Leave a post-cast expansion reinforcement strip at the mid-span of the common wall location to divide the water collection tank into two parts for construction: the side where the water collection tank and the water intake tank do not intersect and the side where the water collection tank and the water intake tank intersect. Step 4: Construct the bottom slab of the water collection tank on the side where the water collection tank and the water intake tank do not intersect, and at the same time construct the tank wall of the water intake tank. Step 5: Construct the beams, columns, and walls of the water collection tank on the side where the water collection tank and the water intake tank do not intersect, and simultaneously construct the walls of the water intake tank. Step 6: Construct the bottom slab of the water collection tank on the side where the water collection tank intersects with the water intake tank, and pour it at the same time as the wall of the water intake tank; Step 7: Construct the top slab of the water intake pool and the columns and beams on the side where the water collection pool intersects with the water intake pool.

2. The method according to claim 1, characterized in that: In step two, before the excavation of the water intake pool, the foundation pit of the water intake pool is supported by a retaining system of steel sheet piles and steel supports.

3. The method according to claim 2, characterized in that: In step two, after the excavation of the water intake pool, a 50mm thick reinforced concrete slope protection is constructed on the secondary slope of the water intake pool.

4. The method according to claim 1 or 3, characterized in that: In step three, double-layer dense-hole steel wire mesh is used on both sides of the post-cast expansion reinforcement strip to separate the concrete inside the strip from the concrete outside the strip. Water-stop steel plates are arranged along the entire length of the bottom plate of the water collection pool at the expansion reinforcement strip to cut off the water seepage path at the construction joint between the old and new concrete at the expansion reinforcement strip.

5. The method according to claim 4, characterized in that: In step three, after the concrete is poured on both sides of the bottom slab of the water collection tank for 28 days, a post-cast expansion reinforcement strip is poured.

6. The method according to claim 5, characterized in that: In step three, the amount of cementitious material used in the shrinkage-compensating concrete on both sides of the expansion reinforcement strip is ≥340kg / m³.

7. The method according to claim 6, characterized in that: In step three, the amount of cementitious material used in the shrinkage-compensating concrete within the expansion reinforcement strip is ≥360kg / m³, and the water-cement ratio is ≤0.

40.

8. The method according to claim 1 or 7, characterized in that: In steps four, five, and six, the pouring sequence of the water intake tank wall is to pour it evenly and symmetrically in layers along the base plate, with each layer not exceeding 300mm in height.

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