A cylinder type fan foundation structure for collapsible loess area and construction method thereof

Abstract

The application provides a cylinder type fan foundation structure and construction method for collapsible loess area, adopts dry operation drilling and engagement construction method to form a large diameter cylinder type foundation pit structure; after installing the steel cage module combination on the ground, the positioning device is used to hoist and place the steel cage into the designated position of the foundation pit; an artificial operation well is arranged inside the cylinder type foundation pit to weld the segmented steel bars; the large diameter cylinder type foundation pit does not set a formwork and pours the concrete integrally; the upper part of the large diameter cylinder type structure and the exposed steel bars are inserted into the pile cap and are poured in the concrete of the pile cap. The application fully utilizes the engineering mechanics characteristics of the high cohesion index of the collapsible loess, adopts the engagement hole forming to form the large diameter foundation pit groove structure to pour the concrete integrally for the cylinder type structure, realizes the one-time pouring and integral forming, and better ensures the integrity of the cylinder type structure; saves the cutting concrete engineering quantity loss of more than 10% during the previous and subsequent pile construction, and improves the work efficiency by more than 2 times.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of wind turbine foundation, in particular to a cylinder type wind turbine foundation structure and construction method for collapsible loess area. BACKGROUND

[0002] The wind turbine foundation is an important part of wind farm construction, which not only relates to the safe and reliable operation of the wind farm, but also affects the investment of the wind farm. With the wind farm construction area becoming more and more extensive, in the areas with poor engineering characteristics such as cohesive soil, silt, silt, and fill, the natural foundation cannot meet the construction requirements of the wind turbine foundation, and the foundation treatment is needed. In collapsible loess area, the common cast-in-place pile wind turbine foundation is usually used, and the large-diameter cylinder type wind turbine foundation adopts the conventional interlocking pile or continuous wall type to form a cylinder structure. The cylinder structure does not fully utilize the engineering characteristics of collapsible loess, and the interlocking of the pre-sequence pile causes waste of the interlocking part of the pre-sequence pile during the construction of the second sequence pile. The construction of the underground continuous wall also has difficulty in solving the problem of the integrity of the connection structure at the joint. The engineering characteristics of collapsible loess are high cohesion index, and the hole formed by the pile is stable without protection. According to the geological condition characteristics, the large-diameter cylinder type wind turbine foundation is invented and innovated. SUMMARY

[0003] The present application provides a cylinder type wind turbine foundation structure and construction method for collapsible loess area, which fully utilizes the engineering mechanics characteristics of high cohesion index of collapsible loess, adopts dry drilling and interlocking construction method to form large-diameter cylinder type foundation pit structure, and precast reinforcement cage module on the ground. After positioning and sinking into the foundation pit structure, the large-diameter cylinder structure is integrally poured to realize one-time pouring and integral forming, which better ensures the integrity of the cylinder structure and reduces the waste of cutting concrete quantity during the construction of the pre-sequence pile and the post-sequence pile.

[0004] In order to achieve the above purpose, the technical scheme adopted by the present application is as follows: a large-diameter cylinder type wind turbine foundation structure for collapsible loess area, comprising a circular expansion foundation slab and a cylinder structure, the bottom of the circular expansion foundation slab is connected to the top of the cylinder structure, a reinforcement cage integral structure is arranged in the cylinder structure, the reinforcement cage integral structure is provided with vertical joints, the reinforcement cage integral structure comprises a plurality of reinforcement cage modules, the reinforcement cage modules are connected at the vertical joints, and the inner side of the cylinder structure is original soil.

[0005] The reinforcement cage integral structure comprises horizontal reinforcement and vertical reinforcement, the horizontal reinforcement and the vertical reinforcement are arranged in cross and connected with each other, and are arranged as double layers to form inner and outer double-layer reinforcement nets, and construction reinforcement is arranged between the inner layer and the outer layer of reinforcement.

[0006] The plurality of positioning steel is arranged at intervals around the foundation pit wall of the side of the cylindrical structure, the steel cage is provided with an outward positioning steel bar on the overall structure, the position of the outward positioning steel bar corresponds to the position of the positioning steel, the outward positioning steel bar is connected with the positioning steel, and the positioning steel is made of an I-shaped steel or a channel steel; the interval between the two adjacent positioning steels is 3-5m.

[0007] The cylindrical structure extends into the circular expanded foundation slab by not less than 100mm, the exposed vertical steel bars are arranged at the top of the cylindrical structure, the exposed vertical steel bars extend into the slab by not less than 35d length, and d is the diameter of the exposed vertical steel bars.

[0008] The diameter of the cylindrical foundation pit structure is 12-14m, the minimum width is 500mm, the depth is 12-15m, and the concrete grade of the cylindrical structure is not less than C30.

[0009] The length of each segment of the vertical segmented steel cage module is not more than the maximum length of the steel, when the cylindrical structure adopts a polygonal form, the horizontal distance between the segmented position and the polygon intersection position is greater than 1m.

[0010] The two adjacent steel cage modules adopt the welding of horizontal steels or adopt vertical U-shaped steel connection.

[0011] The construction method for the large-diameter cylindrical fan foundation structure in the collapsible loess area comprises the following steps:

[0012] The large-diameter cylindrical foundation pit is constructed.

[0013] The steel cage module is made.

[0014] The steel cage module is sunk.

[0015] The vertical connection of the steel cage module is achieved by manual operation of the well welding construction, and the overall structure of the steel cage is formed.

[0016] The overall pouring of the cylindrical structure is performed.

[0017] The circular expanded foundation slab is poured.

[0018] The construction of the large-diameter cylindrical foundation pit comprises the following steps:

[0019] The two-sequence construction method is used to drill and take out soil to form a foundation pit groove, dry drilling is adopted, single-number piles are drilled first, and double-number piles in the middle are drilled.

[0020] The positioning steel is punched into the inside of the foundation pit.

[0021] The hole is drilled at the joint position in the inside of the foundation pit, the manual operation well is arranged at the vertical joint of the steel cage module, and the manual operation well is backfilled after pouring is completed.

[0022] The steel reinforcement cage module is prefabricated on the ground, and the inner steel reinforcement net and the outer steel reinforcement net are horizontally layered and bound; after the layered binding is completed, a number of jacks, lifting or supporting devices satisfying the support requirement are inserted in the middle of the steel reinforcement net, the upper layer of the steel reinforcement net is translated and lifted to the design requirement, and the construction steel reinforcement between the two layers of the steel reinforcement net is bound again.

[0023] Compared with the prior art, the present application has at least the following beneficial effects: the large-diameter cylindrical structure is integrally poured to realize one-time pouring and integral molding, and the integrity of the cylindrical structure is better ensured; in terms of engineering quantity, when the traditional interlocking pile construction is poured in sequence, the concrete of the interlocking part needs to be cut for the front sequence pile, and the engineering quantity loss accounts for not less than 10% of the total quantity, and the present application can save the corresponding engineering quantity; in terms of work efficiency, the traditional interlocking pile construction method needs to retard the setting of concrete, and the entire cylindrical foundation construction takes about 10-15 days, and the method of the present application can be shortened to 3-5 days, and the work efficiency is improved by more than 2 times. BRIEF DESCRIPTION OF DRAWINGS

[0024] Figure 1 It is a structural schematic elevation view that can be implemented by the present application.

[0025] Figure 2 It is a structural schematic plan view that can be implemented by the present application.

[0026] Figure 3 It is a three-dimensional schematic view of main components of the present application.

[0027] Figure 4 It is a construction process flow chart of the present application.

[0028] In the figure: 1-round expansion foundation; 2-cylindrical structure; 3-steel reinforcement cage whole; 4-horizontal steel reinforcement; 5-vertical steel reinforcement; 6-positioning steel; 7-outer protruding positioning steel; 8-manual operation well; 9-steel reinforcement cage split line. DETAILED DESCRIPTION

[0029] The present application will be explained in detail below in combination with the drawings and specific embodiments.

[0030] REFERENCE Figure 1 and Figure 2 A large-diameter cylindrical fan foundation for collapsible loess includes a round expansion foundation pile cap 1 and a cylindrical structure 2, the bottom of the round expansion foundation pile cap 1 is connected to the top of the cylindrical structure 2, a steel reinforcement cage whole structure 3 is arranged in the cylindrical structure 2, the steel reinforcement cage whole structure 3 adopts vertical split, and the steel reinforcement cage split line 9 of the steel reinforcement cage whole structure refers to Figure 2 .

[0031] Figure 2As shown, the foundation pit is formed by front and rear sequential drilling, positioning steel 6 is arranged on the inner side wall of the foundation pit for positioning and sinking of the reinforcement cage module; and an artificial operation well 8 is arranged at the position of the reinforcement cage joint line 9 for joint construction and processing of the reinforcement cage module; the positioning steel 6 adopts I-beam or channel steel.

[0032] Figure 3 As shown in the three-dimensional perspective view of the reinforcement cage whole 3, the reinforcement cage whole 3 includes horizontal reinforcement 4 and vertical reinforcement 5, the horizontal reinforcement 4 and the vertical reinforcement 5 are arranged in cross and connected with each other, and are arranged as double layers to form inner and outer double-layer reinforcement meshes, and an outward positioning reinforcement 7 is arranged outside the inner and outer double-layer reinforcement meshes, and the outward positioning reinforcement 7 corresponds to the position of the positioning steel 6 of the inner wall of the foundation pit.

[0033] The large-diameter cylindrical foundation pit structure is formed by adopting dry drilling and drilling and interlocking construction method;

[0034] After the reinforcement cage module is combined and installed on the ground, the positioning device is used to hoist and place it into the designated position of the foundation pit;

[0035] The artificial operation well is arranged inside the cylindrical foundation pit, and the segmented reinforcement is welded;

[0036] The large-diameter cylindrical foundation pit does not arrange a formwork, and the whole is poured with concrete; the upper part of the large-diameter cylindrical structure and the exposed reinforcement are extended into the pile cap and poured in the concrete of the pile cap.

[0037] The cylindrical foundation pit structure formed after the dry drilling and interlocking construction has a diameter of 12-14 m, a minimum width of 500 mm, and a depth of 12-15 m in general.

[0038] The vertical joint connection is adopted between the reinforcement cage modules, and the length of each segment of the reinforcement cage module after segmentation is not more than 9 m, which is the maximum length of the reinforcement; when the large-diameter cylindrical structure adopts a polygonal form, the horizontal distance between the segmented position and the polygon intersection position should be greater than 1 m.

[0039] The single reinforcement cage module includes two layers of reinforcement meshes inside and outside the foundation pit, the reinforcement meshes include vertical reinforcement and horizontal ring reinforcement, and the structural reinforcement is arranged between the two layers of reinforcement meshes.

[0040] A positioning steel 6 is punched into the corresponding position inside the cylindrical foundation pit at intervals of 3-5 m, the opening faces away from the center of the cylindrical shape, and faces the inside of the pit. The reinforcement cage module is provided with an outward positioning reinforcement at the position of the positioning steel 6 on the inner and outer layers of reinforcement meshes, and the positioning steel of the inner layer of reinforcement meshes is consistent with the positioning steel in the pit groove in terms of spacing and position. When the reinforcement cage is lowered, the positioning steel should be smoothly inserted into the positioning steel 6, and the reinforcement cage is lowered to the bottom of the cylindrical foundation pit.

[0041] In the segment joint position of the foundation pit, the inside dry drilling forms a manual operation well, and after the steel reinforcement modules are placed on both sides, the horizontal steel reinforcement is welded or connected by vertical U-shaped steel reinforcement.

[0042] When prefabricating on the ground, the inside and outside steel reinforcement meshes are horizontally layered and bound; after the layered binding is completed, a number of jacks, hoists or support devices that meet the support requirements are inserted in the middle of the steel reinforcement mesh, the upper steel reinforcement mesh is translated and raised to the design requirements, and the binding of the structural reinforcement between the two layers of steel reinforcement meshes is then performed.

[0043] The drilling and soil extraction adopts a two-sequence construction method, in which single-number piles are drilled first, and double-number piles in the middle are drilled later to ensure the force balance of the drilling machine.

[0044] For the large-diameter cylindrical foundation pit, no formwork is arranged, the steel reinforcement cage module is sunk and connected, and then the whole concrete is poured, and the concrete grade is not less than C30; the upper structure of the large-diameter cylindrical structure extends into the main structure of the pile cap by not less than 100 mm, and the exposed vertical steel reinforcement extends into the pile cap by not less than 35d length, and is poured in the pile cap concrete in the later stage.

[0045] Reference Figure 4 The construction method comprises the following steps:

[0046] Constructing a large-diameter cylindrical foundation pit;

[0047] Manufacturing a steel reinforcement cage module;

[0048] Sinking the steel reinforcement cage module;

[0049] Vertically connecting the steel reinforcement cage module by welding in the manual operation well, and completing the whole structure of the steel reinforcement cage

[0050] Pouring the whole cylindrical structure;

[0051] Pouring the circular expanded foundation pile cap.

[0052] Constructing a large-diameter cylindrical foundation pit comprises the following steps:

[0053] Drilling and soil extraction by a two-sequence construction method to form a foundation pit groove;

[0054] Driving a positioning profile steel into the inside of the foundation pit;

[0055] Drilling a hole at the joint position of the inside of the foundation pit to set a manual operation well.

[0056] Manufacturing a steel reinforcement cage module on the ground by prefabricating, horizontally layering and binding the inside and outside steel reinforcement meshes; after the layered binding is completed, a number of jacks, hoists or support devices that meet the support requirements are inserted in the middle of the steel reinforcement mesh, the upper steel reinforcement mesh is translated and raised to the design requirements, and the binding of the structural reinforcement between the two layers of steel reinforcement meshes is then performed.

Claims

1. A foundation structure for large-diameter cylindrical wind turbines in collapsible loess areas, characterized in that, The structure includes a circular extended foundation (1) and a cylindrical structure (2). The bottom of the circular extended foundation (1) is connected to the top of the cylindrical structure (2). The cylindrical structure (2) contains a steel cage integral structure (3). The steel cage integral structure (3) has vertical joints. The steel cage integral structure (3) includes several steel cage modules. The steel cage modules are connected at the vertical joints. The inner side of the cylindrical structure (2) is undisturbed soil. The length of each segment after the vertical segmentation of the steel cage module does not exceed the maximum length of the steel bar by 9m. When the large-diameter cylindrical structure adopts a polygonal form, the horizontal distance between the segment position and the intersection of the polygon should be greater than 1m. Multiple positioning steel sections (6) are set around the perimeter of the foundation pit wall on the side of the cylindrical structure (2). Outwardly protruding positioning steel sections (7) are set on the steel cage integral structure (3). The position of the outwardly protruding positioning steel section (7) corresponds to the position of the positioning steel section (6). The outwardly protruding positioning steel section (7) is connected to the positioning steel section (6). The positioning steel section (6) is made of I-beams or channel steel. The overall construction method includes the following steps: Construction of large-diameter cylindrical foundation pits; Fabrication of steel cage modules; Reinforcing cage module sinking; The steel cage modules are vertically connected and welded by manual operation in the well (8) to form the overall steel cage structure (3). (2) Integral casting of cylindrical structure; Circular extended foundation cap (1) pouring; construction of large-diameter cylindrical foundation pit includes the following steps: The two-stage construction method involves drilling and soil extraction to form the foundation pit. Dry drilling is adopted, with odd-numbered piles drilled first, followed by even-numbered piles in the middle. Positioning steel sections were driven into the inside of the foundation pit; Drill holes at the joints inside the foundation pit, and set up manual operation wells (8) at the vertical joints of the steel cage formwork. After the pouring is completed, backfill the manual operation wells (8); the cylindrical structure (2) extends into the circular extended foundation platform (1) by no less than 100mm, and exposed vertical steel bars are set at the top of the cylindrical structure (2). The exposed vertical steel bars extend into the platform by no less than 35d in length, where d is the diameter of the exposed vertical steel bars; adjacent steel cage modules are connected by welding horizontal steel bars or by vertical U-shaped steel bars.

2. The foundation structure for large-diameter cylindrical wind turbines in collapsible loess areas according to claim 1, characterized in that, The overall structure of the steel cage (3) includes horizontal steel bars (4) and vertical steel bars (5). The horizontal steel bars (4) and vertical steel bars (5) are arranged in a cross pattern and connected to each other. They are arranged in a double layer to form an inner and outer double-layer steel mesh. Structural steel bars are set between the inner and outer layers of steel bars.

3. The foundation structure for large-diameter cylindrical wind turbines in collapsible loess areas according to claim 1, characterized in that, The diameter of the cylindrical foundation pit structure is 12~14m, the minimum width is 500mm, and the depth is 12~15m; the concrete grade of the cylindrical structure (2) is not lower than C30.

4. The foundation structure for large-diameter cylindrical wind turbines in collapsible loess areas according to claim 1, characterized in that, The steel cage modules are prefabricated on the ground, and the inner and outer steel meshes are horizontally tied in layers. After the layer tying is completed, a number of jacks, lifting or support devices that meet the support requirements are inserted in the middle of the steel mesh to move and raise the upper layer of steel mesh to the design requirements, and then the structural steel bars between the two layers of steel mesh are tied.

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