Precast pedestal for post-reinforcement method pier body segments and construction method

Abstract

The invention provides a post-reinforcement method pier body section prefabricated pedestal and a construction method. The prefabricated pedestal comprises a concrete base, four bearing beams are fixedly arranged on the concrete base, a pier body section bottom formwork is welded to the four bearing beams, a boss is arranged in the middle of the bottom formwork, a movable top plate is arranged at the top of the boss, and a jack is arranged between the movable top plate and the concrete base; the jack stretches to drive the movable top plate to lift; when the prefabricated pedestal is used for manufacturing pier body sections, firstly, hole-forming steel pipes are arranged on a bottom formwork according to the distance between main reinforcements of the pier body sections, the lower end of each hole-forming steel pipe is welded and fixed to the bottom formwork, then annular stirrups and hanging reinforcements are bound, the formworks are installed, and concrete is poured; and after the concrete reaches the demolding strength, the jack pushes upwards, so that dislocation is generated between the pore-forming steel pipe and the concrete, and demolding of the pore-forming steel pipe is achieved. The hole collapse phenomenon of the steel bar preformed holes in the pier body sections can be avoided, hole forming is guaranteed, one-time forming of multiple holes can be achieved, and the construction efficiency is high.

Description

Technical Field

[0001] The invention belongs to the technical field of bridge construction, relates to a prefabricated assembled pier body construction, and specifically relates to a pier body segment prefabricated pedestal and a construction method for assembling the pier body by a post-reinforcement method. Background Art

[0002] Prefabricated assembled piers are made by dividing the pier into multiple prefabricated segments, which are then butted up and down at the pier construction site. One of the segment butt jointing methods is to use the post-reinforcement method. When each segment is prefabricated, the main reinforcement is not installed first, but corresponding steel bar reserved holes are set at the position of each main reinforcement. When the prefabricated segments are installed, the main reinforcement is inserted into each steel bar reserved hole, and the rear-inserted main reinforcement of the upper and lower segments are connected. Then, grouting is injected into the steel bar reserved holes to consolidate the rear-inserted main reinforcement and the pier segment concrete into one. For the assembled pier constructed by this method, the main reinforcement connection method between the prefabricated segments is the same as that of the cast-in-place pier, so its structural strength, shear resistance and other performances are equivalent to those of the cast-in-place pier.

[0003] At present, when processing the post-reinforcement prefabricated pier body segments, the steel bar reserved holes in the pier body segments are all made by pre-embedding core rods in the concrete, and the core rods are pulled out to form holes after the concrete is poured. The core rods are usually pulled out during the initial setting stage of the concrete, but it is difficult for construction workers to accurately grasp the timing of pulling out the core rods. If the demolding is too early, the concrete has not yet reached sufficient solidification strength, and it is easy to collapse the hole or the inner wall of the hole will be rough, which is not conducive to the insertion of steel bars later. If the demolding is too late, it is easy to make the core rod difficult to pull out or even break. Moreover, during the current construction, the core rods are pulled out one by one by hand by the construction workers. There are hundreds or even more steel bar reserved holes on a post-reinforcement prefabricated pier body segment, and the efficiency of manual demolding construction is low. Summary of the invention

[0004] The object of the present invention is to provide a post-reinforcement pier segment prefabricated pedestal and construction method to address the above problems, thereby ensuring the construction quality of the pier segment and improving the construction efficiency.

[0005] The present invention provides a prefabricated pedestal for pier body segments using a post-reinforcement method, which is characterized in that it comprises a concrete base, on which four cushion beams are fixedly arranged, on which a bottom formwork for the prefabricated pier body segment is arranged, the bottom surfaces of the four sides of the bottom formwork are respectively welded to the top surfaces of the four cushion beams, a boss is arranged in the middle of the bottom formwork for forming a positioning groove at the bottom of the pier body segment, the boss is a hollow structure, a movable top plate is arranged on the top of the boss, a jack is arranged between the movable top plate and the concrete base, and the movable top plate can be driven to rise and fall by the extension and retraction of the jack.

[0006] The construction method of manufacturing the post-reinforcement pier body segment by using the above-mentioned prefabricated pedestal is characterized by comprising the following steps:

[0007] (1) According to the main reinforcement spacing of the pier body segment, a hole-forming steel pipe is set on the bottom formwork corresponding to each main reinforcement, and the lower end of each hole-forming steel pipe is welded and fixed to the bottom formwork;

[0008] (2) The circumferential stirrups of the pier body segment are tied around the outer periphery of the hole-forming steel pipe, and four hanger bars are equidistantly welded around the inner side of the circumferential stirrups. The height of the hanger bars is higher than the designed height of the pier body segment. After the hanger bars are welded, the circumferential stirrups are supported and fixed by the hanger bars, and the tying of the circumferential stirrups and the hole-forming steel pipe is released, so as to facilitate the smooth demoulding of the hole-forming steel pipe in the later stage.

[0009] (3) Install the side formwork and top formwork of the pier segment and pour the pier segment concrete; remove the side formwork and top formwork after the concrete reaches the demoulding strength;

[0010] (4) Start the jack to push the pier segment upward, so that there is a displacement between the hole-forming steel pipe and the concrete of the pier segment;

[0011] (5) The lifting device is connected to the upper ends of four lifting rods through steel wire ropes to lift the pier segment off the pedestal;

[0012] (6) The jack returns the oil to return the movable top plate to its original position and prefabricate the next pier segment.

[0013] Compared with the prior art, the present invention has the following beneficial effects:

[0014] 1. The steel pipe can be demoulded after the concrete is completely solidified, which can avoid hole collapse or rough hole wall and ensure the quality of hole formation;

[0015] 2. The use of jack to push the demoulding can achieve one-time forming of multiple holes, with high construction efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 It is a schematic diagram of the structure of the pedestal of the present invention when it is lifted by a jack;

[0017] Figure 2 It is a schematic diagram of the structure of the pedestal of the present invention when the jack is retracted;

[0018] Figure 3 This is a state view of the perforated steel pipe installed on the pedestal;

[0019] Figure 4 This is a schematic diagram of the state after the circumferential reinforcement and hanger reinforcement of the prefabricated pier segment are tied;

[0020] Figure 5 It is a schematic diagram of the state after the concrete pouring of the prefabricated pier segment is completed;

[0021] Figure 6 It is a schematic diagram of the state when the prefabricated pier body segment is lifted by a jack to demould the holed steel pipe. DETAILED DESCRIPTION

[0022] like Figure 1 , Figure 2 As shown, a post-reinforcement method pier body segment prefabricated pedestal provided by the present invention comprises a concrete base 1, on which four cushion beams 2 are fixedly arranged, and a bottom formwork 3 of the prefabricated pier body segment is arranged on the four cushion beams, and the four bottom surfaces of the bottom formwork 3 are respectively welded to the top surfaces of the four cushion beams 2, and a boss 4 for forming a positioning groove at the bottom of the pier body segment is arranged in the middle of the bottom formwork 3, the boss 4 is a hollow structure, and a movable top plate 5 is arranged on the top of the boss, and a jack 6 is arranged between the movable top plate 5 and the concrete base 1, and the movable top plate 5 can be driven to rise and fall by the extension and retraction of the jack 6.

[0023] The construction method of the pier body segment using the above-mentioned pedestal prefabrication and post-reinforcement method comprises the following steps:

[0024] (1) Figure 3 As shown, adjust the height of the jack so that the boss top plate ensures that the boss top is in a closed state; according to the main reinforcement spacing of the pier body segment, set a hole-forming steel pipe 7 on the bottom template 3 corresponding to each main reinforcement, and the lower end of each hole-forming steel pipe 7 is welded and fixed to the bottom template 3; in order to ensure smooth demoulding of the hole-forming steel pipe in the later stage, a release agent can be applied on the outer wall of the hole-forming steel pipe or a layer of plastic film can be covered;

[0025] (2) Figure 4 As shown, the circumferential stirrups 8 of the pier body segment are tied around the outer periphery of the hole-forming steel pipe 7, and four vertical hanger bars 9 are circumferentially equidistantly welded inside the circumferential stirrups 8, and the height of the hanger bars is higher than the design height of the prefabricated pier body segment; each hanger bar is welded to the circumferential stirrups, and after the hanger bar welding is completed, the circumferential stirrups 8 are supported and fixed by the hanger bars 9, and the binding of the circumferential stirrups and the hole-forming steel pipe is released, so as to facilitate the smooth demoulding of the hole-forming steel pipe in the later stage;

[0026] (3) Figure 5 As shown, the side formwork and top formwork of the pier body segment are installed, and the prefabricated pier body segment concrete is poured; after the concrete reaches the demoulding strength, the side formwork and top formwork are removed;

[0027] (4) Figure 6 As shown, the jack is started to push the pier body segment 10 upward, so that a displacement occurs between the hole-forming steel pipe and the pier body segment concrete, and the pier body segment slides upward along the hole-forming steel pipe to a certain height;

[0028] (5) The lifting device is connected to the upper ends of four lifting rods through steel wire ropes to lift the pier segment upward from the pedestal;

[0029] (6) The oil on the jack is returned to the movable top plate, and the next pier segment is prefabricated according to the method of steps (2) to (4).

Claims

1. A post-reinforcement method pier segment prefabricated pedestal, characterized in that: It includes a concrete base, on which four cushion beams are fixedly arranged, on which a bottom formwork of a prefabricated pier body segment is arranged, the bottom surfaces of the four sides of the bottom formwork are respectively welded to the top surfaces of the four cushion beams, a boss is arranged in the middle of the bottom formwork for forming a positioning groove at the bottom of the pier body segment, the boss is a hollow structure, a movable top plate is arranged on the top of the boss, a jack is arranged between the movable top plate and the concrete base, and the movable top plate can be driven to rise and fall by the extension and retraction of the jack.

2. A method for prefabricating pier body segments by the rear reinforcement method, using the pier body segment prefabrication pedestal according to claim 1, characterized in that: The following steps are involved: (1) According to the main reinforcement spacing of the pier body segment, a hole-forming steel pipe is set on the bottom formwork corresponding to each main reinforcement, and the lower end of each hole-forming steel pipe is welded and fixed to the bottom formwork; (2) The circumferential stirrups of the pier body segment are tied around the outer periphery of the hole-forming steel pipe, and four hanger bars are equidistantly welded around the inner side of the circumferential stirrups. The height of the hanger bars is higher than the designed height of the pier body segment. After the hanger bars are welded, the circumferential stirrups are supported and fixed by the hanger bars, and the tying of the circumferential stirrups and the hole-forming steel pipe is released, so as to facilitate the smooth demoulding of the hole-forming steel pipe in the later stage. (3) Install the side formwork and top formwork of the pier segment and pour the pier segment concrete; remove the side formwork and top formwork after the concrete reaches the demoulding strength; (4) Start the jack to push the pier body segment upward to cause displacement between the bored steel pipe and the concrete; (5) The lifting device is connected to the upper ends of four lifting rods through steel wire ropes to lift the pier segment off the pedestal; (6) The jack returns the oil to return the movable top plate to its original position and prefabricate the next pier segment.

Images