Stand column lengthening structure and construction method

Abstract

The invention discloses a stand column lengthening structure and a construction method.The stand column lengthening structure comprises a diagonal brace, a first stand column and a lengthening part used for lengthening the first stand column, the two ends of the diagonal brace are connected to side walls on the two opposite sides of a foundation pit correspondingly, and the first stand column comprises a connecting part and a pile foundation which are sequentially connected from top to bottom; the ends, away from the pile foundations, of the connecting parts are connected to the diagonal bracings, the pile foundations are embedded in earthwork of the foundation pit, the depth of the bottom ends of the pile foundations is lower than the first preset depth of the foundation pit, the extension parts comprise steel pipe piles extending in the vertical direction, the steel pipe piles are embedded in the earthwork of the foundation pit and connected to the pile foundations, and the steel pipe piles and the first stand columns are connected to form second stand columns. The length of the first stand column is increased through the steel pipe pile, the cost for manufacturing a new stand column meeting the length is reduced, meanwhile, the original first stand column does not need to be pulled out and abandoned, the labor cost is reduced, and the construction period is shortened.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of foundation pit support, in particular to a column lengthening structure and a construction method. BACKGROUND

[0002] When constructing a building, a foundation pit is excavated on the ground as the foundation of the building, support piles are constructed at the positions of the predetermined side walls of the foundation pit to form support side walls, inner supports are connected on two adjacent support side walls, opposite supports are connected on two opposite support side walls, and the opposite supports are vertically supported by columns, and then the earthwork is excavated to the predetermined depth.

[0003] However, in actual construction, the excavation depth of the foundation pit often needs to be increased after the construction of the columns is completed. At this time, the length of the original columns inserted into the earthwork of the deepened foundation pit is insufficient, and cannot provide sufficient bearing capacity. Therefore, the already completed columns need to be pulled out of the earthwork of the foundation pit, and columns with sufficient length need to be newly manufactured and constructed.

[0004] In view of the above related technology, the re-construction of columns with sufficient length greatly prolongs the construction period, and the abandonment of the original columns increases the project cost. SUMMARY

[0005] The present application aims to provide a column lengthening structure and a construction method to solve one or more technical problems existing in the prior art, and at least provide a beneficial choice or create conditions.

[0006] The solution to the technical problem of the present application is: In a first aspect, the present application provides a column lengthening structure, which comprises: an opposite support extending along a horizontal direction, two ends of the opposite support being connected to side walls on opposite sides of a foundation pit for use with the column lengthening structure; a first column disposed in the middle of the foundation pit, the first column comprising a connecting portion and a pile foundation connected in sequence from top to bottom, an end of the connecting portion away from the pile foundation being connected to the opposite support, the pile foundation being embedded in the earthwork of the foundation pit and having a bottom end at a depth lower than a first predetermined depth of the foundation pit; an extension portion comprising a steel pipe pile extending in a vertical direction, the steel pipe pile being embedded in the earthwork of the foundation pit, a top end of the steel pipe pile being at a depth higher than a bottom of the pile foundation, a bottom end of the steel pipe pile being at a depth lower than a second predetermined depth of the foundation pit, the second predetermined depth being lower than the first predetermined depth, the steel pipe pile being connected to the pile foundation, and the steel pipe pile and the first column forming a second column after being connected.

[0007] The technical scheme has at least the following beneficial effects: after the construction of the first column is completed and the connection between the first column and the strutting is completed, the first column is fixed in the foundation pit and cannot be moved, the first column can only provide sufficient bearing capacity for the strutting in the range from the ground to the first predetermined depth, the construction personnel can excavate the earthwork in the foundation pit to the first predetermined depth, then a steel pipe pile serving as an extension part is constructed on the side of the first column until the steel pipe pile is buried at a predetermined position below the first predetermined depth, so that the length of the steel pipe pile and the first column minus the length of the overlapping part is the length of the second column in the vertical direction, at this time, the second column meets the required length at the second predetermined depth in the foundation pit, can provide stable vertical support for the strutting, and enables the construction personnel to stably excavate the earthwork to the second predetermined depth. Through the scheme, the cost required for newly manufacturing a column meeting the length is reduced, and the original first column does not need to be pulled out and discarded, thereby reducing the labor cost and construction period.

[0008] As a further improvement of the above technical scheme, the extension part comprises a plurality of steel pipe piles, the plurality of steel pipe piles are arranged around the pile foundation, and the plurality of steel pipe piles are all abutted to the pile foundation, and the column lengthening mechanism further comprises a connecting assembly for connecting the pile foundation and the plurality of steel pipe piles.

[0009] Through the above technical scheme, first, after the first column is constructed, the plurality of steel pipe piles are constructed to the predetermined position before the strutting is installed, which reduces the obstruction to the installation of the steel pipe piles located directly below the strutting after the strutting is installed, second, it is convenient for the construction personnel to construct the steel pipe piles on the ground plane of the foundation pit by various construction equipment such as a pile machine, third, the plurality of steel pipe piles are in close contact around the pile foundation, which can support the pile foundation in the middle from multiple directions, for example, when the first column only supports one strutting, the steel pipe piles located directly below the two side edges of the strutting can support the pile foundation of the first column from the side edges, so that when the strutting bends in the direction perpendicular to the axial direction of the strutting, the earthwork gives the entire bottom of the second column a force in the horizontal direction perpendicular to the axial direction of the strutting through the steel pipe piles, thereby offsetting the force of the strutting in the direction perpendicular to the axial direction of the strutting, reducing the deformation of the strutting in the direction, and greatly improving the stability of the strutting, in addition, because the newly added steel pipe piles are constructed around the original pile structure, part of the steel pipe piles in the formed second column can clamp the pile foundation of the first column and the earthwork, forming a larger cross-sectional diameter, which can provide greater bearing capacity, and the steel pipe piles clamp the earthwork inside to form an earth column, thereby reducing the manufacturing cost required for manufacturing a large-diameter column.

[0010] As a further improvement of the above technical solution, the connecting assembly comprises a clamp, the extension part is sleeved with a plurality of clamps in sequence from top to bottom, and the height of the lowermost clamp is higher than the second predetermined depth.

[0011] By adopting the above technical solution, the clamps are sleeved on the plurality of steel pipe piles of the extension part, so that the one end of the plurality of steel pipe piles away from the soil can better clamp the intermediate pile foundation, thereby improving the structural stability of the entire second column and providing stable support for the support.

[0012] As a further improvement of the above technical solution, a plurality of diagonal braces are arranged on the connecting part in the circumferential direction, and one end of the plurality of diagonal braces away from the connecting part is connected to the top of the extension part.

[0013] By adopting the above technical solution, the diagonal brace is connected to the connecting part and the extension part at the same time, forming a stable triangular posture, so that the extension part with a larger cross-sectional diameter can support the connecting part with a smaller cross-sectional diameter in the circumferential direction, further improving the overall structural stability of the second column.

[0014] As a further improvement of the above technical solution, it further comprises an end cover, the end cover is arranged on the extension part, the end cover is provided with a position avoiding hole for the connecting part to extend out, and one end of the plurality of diagonal braces away from the connecting part is connected to the end cover.

[0015] By adopting the above technical solution, in order to stably connect the diagonal brace to each steel pipe pile of the extension part, the end cover is installed on the extension part, so as to close the end part of the hollow steel pipe pile, and further form a platform above the end cover for construction, and the one end of the diagonal brace away from the column is fixed on the end cover, thereby improving the connection stability between the diagonal brace and the extension part.

[0016] As a further improvement of the above technical solution, the connecting part is provided with a connecting rib extending in the horizontal direction, both ends of the connecting rib pass through the connecting part, and the end of the connecting rib is connected with the end cover.

[0017] By adopting the above technical solution, after the connecting rib is fixed on the end cover, the connecting rib connects the connecting part and the end cover, and further improves the connection strength between the connecting part and the extension part through the end cover and the connecting rib, thereby improving the overall structural stability of the second column.

[0018] As a further improvement of the above technical solution, the end cover comprises a sleeving part and a covering part connected with each other, the sleeving part is sleeved on the extension part, the covering part comprises two semicircular ring plates connected with each other, one of the semicircular ring plates is provided with an avoiding slot on the side close to the other semicircular ring plate, and the avoiding slots of the two semicircular ring plates form the avoiding hole, and the semicircular ring plates are both covered on the extension part.

[0019] When the end cover is installed, the pit is excavated to the second predetermined depth before the installation of the end cover, and at this time the extension part has been connected with the pile foundation of the first stand column, so the end cover cannot be directly sleeved. By adopting the above technical solution, appropriate size steel is selected, a rectangular plate with a length of the circumference of the extension part and a circular plate with a radius of the extension part are cut out, the rectangular plate is enclosed at the top of the extension part to form the sleeving part, the circular plate is cut into two semicircular ring plates with avoiding slots, the semicircular ring plates are covered on the upper end of the extension part, the two semicircular ring plates are welded and fixed, and the semicircular ring plates and the sleeving part are welded and fixed to obtain the end cover. This scheme can quickly install the end cover on the extension part, and can use the on-site steel materials, and only needs cutting and welding on site to achieve the end cover, which is convenient for construction personnel to quickly process.

[0020] As a further improvement of the above technical solution, the depth of the bottom end of the pile foundation is greater than the second predetermined depth.

[0021] By adopting the above technical solution, the length of the pile foundation is limited to be able to extend into the pit earthwork excavated to the second predetermined depth. At this time, the pile foundation still has a connection with the pit earthwork, and forms a three-layer laminated structure with the pit earthwork and the steel pipe pile. The earthwork in the outermost layer clamps the steel pipe pile and the pile foundation in turn, and the connection stability between the steel pipe pile and the pile foundation is strengthened.

[0022] In a second aspect, the application provides a construction method applied to the stand column lengthening structure provided in the first aspect of the application, and the construction method comprises the following steps: constructing a side wall at a predetermined position of a pit, and sequentially constructing a first stand column and an extension part; installing a counter support and connecting the counter support to the first stand column; excavating pit earthwork until a first predetermined depth, and connecting the extension part with the first stand column; continuing to excavate the pit earthwork until a second predetermined depth.

[0023] The technical scheme has at least the following beneficial effects: when the earthwork between the first predetermined depth and the second predetermined depth is continuously excavated, a greater column axial force compared with the original design is transmitted to the newly constructed steel pipe pile, and then the increased force is transmitted to the deeper soil layer through the steel pipe pile, thereby compensating for the problem of insufficient vertical bearing capacity of the first column pile foundation after the foundation pit is deepened, and the force can be successfully converted to the newly added structure, thereby improving the stability of the support in the foundation pit.

[0024] As a further improvement of the above technical scheme, the continuing excavation of the earthwork of the foundation pit to the second predetermined depth comprises: excavating the earthwork and sleeving the clamp on the extension part.

[0025] By adopting the above technical scheme, when the earthwork between the first predetermined depth and the second predetermined depth is excavated, the steel pipe pile that has been constructed will gradually expose the outer wall, which facilitates the fixing of the clamp on the outer wall of the steel pipe pile by the construction personnel, thereby reducing the construction difficulty. BRIEF DESCRIPTION OF DRAWINGS

[0026] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings needed in the embodiment description will be briefly described in the following. Obviously, the described drawings are only a part of the embodiments of the present application, and not all embodiments. Those skilled in the art can also obtain other design schemes and drawings from these drawings without creative labor.

[0027] Figure 1 is a schematic view of the overall structure of the foundation pit from a top view angle of the present application; Figure 2 is a schematic view of the position relationship of the parts of the second column when the foundation pit earthwork is buried; Figure 3 is a schematic view of the overall structure of the second column of the present application; Figure 4 is a sectional view of the A-A view in Figure 3 ; Figure 5 is a partial structure sectional view of the B-B view in Figure 3 ; Figure 6 is a sectional view of the C-C view in Figure 3 . DETAILED DESCRIPTION

[0028] The embodiments of the present application will be described in detail below, and the examples of the embodiments are shown in the drawings, wherein the same or similar reference numerals represent the same or similar elements or elements having the same or similar functions throughout. The embodiments described below by referring to the drawings are exemplary and are only used to explain the present application, and cannot be understood as a limitation of the present application.

[0029] In the description of the present application, it should be understood that the orientation description, such as the orientation or position relationship indicated by the upper, lower, front, rear, left, right and the like, is based on the orientation or position relationship shown in the drawings, only for the purpose of facilitating the description of the present application and simplifying the description, and does not indicate or imply that the device or element referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as a limitation on the present application.

[0030] In the description of the present application, one or more is understood as one or more, more than two is understood as more than two, greater than, less than, more than, etc. are understood as not including the number, above, below, etc. are understood as including the number. If the first, second is described, it is only for the purpose of distinguishing technical features, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of indicated technical features or the sequence of indicated technical features.

[0031] In the description of the present application, unless otherwise explicitly limited, the words such as setting, installing, connecting and the like should be broadly understood, and those skilled in the art can reasonably determine the specific meaning of the above words in the present application in combination with the specific content of the technical solution.

[0032] The foundation pit construction is a necessary step for the construction of existing buildings. The existing foundation pit construction steps are to construct a support side wall and excavate earthwork. In order to improve the stability of the foundation pit, an inner support is arranged between two adjacent side walls of the foundation pit, and a counter support is arranged between the opposite two side walls. Before the counter support is installed, a column capable of being connected with the counter support is constructed on the unexcavated foundation pit earthwork. After the foundation pit is excavated, the column provides vertical support force for the counter support, improves the support stability of the counter support to the side wall, and reduces the deformation of the counter support after the side wall of the foundation pit extrudes the counter support.

[0033] In the actual construction process, the pile foundation of the column is manufactured by drilling and pouring concrete, the steel structure of the column is combined with the pile foundation, and finally the counter support is welded and fixed with the steel structure of the column. After the concrete of the pile structure is solidified, the foundation pit is excavated.

[0034] However, between the solidification of the concrete and the construction of the counter support, the design depth of the foundation pit often changes due to different reasons. When the design depth of the foundation pit needs to be increased, the already constructed column is not long enough to extend into the earthwork after the design depth changes, the friction between the column pile side and the earthwork is reduced, and the column bearing capacity is lower than the original design. If the earthwork is directly excavated to the changed depth, the accident risk will be greatly increased. The existing solution is to remove the entire column that has been constructed and construct a column with sufficient length. However, this solution requires a lot of manpower and resources, prolongs the construction period and increases the construction cost. Therefore, the present application provides a solution that can lengthen the existing column and improve the stability of the counter support structure.

[0035] In a first aspect, the application provides a column lengthening structure, which is used in cooperation with a foundation pit 1 and side walls 11 thereof, and is described in a completed state in the embodiment. In the embodiment, the column lengthening structure comprises a bracing 12, a first column 2, and an extension 3 for extending the first column 2. The design depth of the foundation pit 1 can vary throughout the entire foundation pit 1 or only in the part of the foundation pit 1 that covers the earthwork where the first column 2 is located. Figure 1 and Figure 2 The column lengthening structure of the embodiment is described in a completed state. In the embodiment, the column lengthening structure comprises a bracing 12, a first column 2, and an extension 3 for extending the first column 2. In the embodiment, the design depth of the foundation pit 1 can vary throughout the entire foundation pit 1 or only in the part of the foundation pit 1 that covers the earthwork where the first column 2 is located.

[0036] Specifically, referring to Figure 2 and Figure 3 The bracing 12 extends in a direction parallel to the horizontal direction. The two ends of the bracing 12 are connected to the side walls 11 on opposite sides of the foundation pit 1. The first column 2 is arranged at a midpoint of the bracing 12 in the middle of the foundation pit 1. The first column 2 comprises a connecting portion 21 and a pile foundation 22 connected in sequence from top to bottom. The end of the connecting portion 21 away from the pile foundation 22 is connected to the bracing 12. The pile foundation 22 is embedded in the earthwork in the foundation pit 1, and the lower end of the pile foundation 22 is at a depth lower than a first predetermined depth of the foundation pit 1. The extension 3 comprises a steel pipe pile 31 extending in the vertical direction. The steel pipe pile 31 is embedded in the earthwork in the foundation pit 1. The top end of the steel pipe pile 31 is at a depth between the top and bottom of the pile foundation 22. The bottom end of the steel pipe pile 31 is at a second predetermined depth of the foundation pit 1, which is lower than the first predetermined depth. The steel pipe pile 31 is connected to the pile foundation 22. After the steel pipe pile 31 and the first column 2 are connected, a second column 4 is formed.

[0037] As can be seen from the above, after the construction of the first column 2 and the connection of the first column 2 and the bracing 12 are completed, the first column 2 is fixed in the foundation pit 1 and cannot be moved. The first column 2 can only provide sufficient bearing capacity for the bracing 12 within the range from the ground to the first predetermined depth, so as to facilitate the construction personnel to excavate the earthwork in the foundation pit 1 to the first predetermined depth. Then, the steel pipe pile 31 serving as the extension 3 is constructed on the side of the first column 2 until the steel pipe pile 31 is embedded in the earthwork at a predetermined position lower than the first predetermined depth. The length of the second column 4 in the vertical direction is the sum of the lengths of the steel pipe pile 31 and the first column 2 minus the length of the overlapping part of the two. At this time, the second column 4 satisfies the required length at the second predetermined depth of the foundation pit 1, and can provide stable vertical support for the bracing 12, so that the construction personnel can stably excavate the earthwork to the second predetermined depth. Through the scheme, not only the cost required for newly manufacturing a column satisfying the length is reduced, but also the original first column 2 does not need to be pulled out and discarded, thereby reducing the labor cost and the construction period.

[0038] In order to support the pile foundation 22 in all directions and improve the structural stability of the first column 2, referring to Figures 3-4The extension part 3 comprises a plurality of steel pipe piles 31 arranged along the circumference of the pile foundation 22, and the adjacent two steel pipe piles 31 abut each other, and the plurality of steel pipe piles 31 abut the pile foundation 22. The column lengthening mechanism further comprises a connecting assembly 5 for connecting the pile foundation 22 and the plurality of steel pipe piles 31.

[0039] Firstly, after the construction of the first column 2, the plurality of steel pipe piles 31 are installed to the predetermined position before the installation of the counterbrace 12, which reduces the obstruction to the installation of the steel pipe piles 31 located directly below the counterbrace 12 after the installation of the counterbrace 12. Secondly, it is convenient for the construction personnel to perform the construction on the steel pipe piles 31 on the ground surface of the foundation pit 1 by using various construction equipment such as a pile driver. Thirdly, the plurality of steel pipe piles 31 are in close contact around the pile foundation 22, which can support the pile foundation 22 in the middle from multiple directions. For example, when the first column 2 supports only one counterbrace 12, the steel pipe piles 31 located directly below the two side edges of the counterbrace 12 can support the pile foundation 22 of the first column 2 from the side edges. When the counterbrace 12 bends in the direction perpendicular to the axial direction of the counterbrace 12, the earth force is applied to the bottom of the entire second column 4 in the direction perpendicular to the axial direction of the counterbrace 12 through the steel pipe piles 31, so as to offset the force applied to the counterbrace 12 in the direction perpendicular to the axial direction of the counterbrace 12, thereby reducing the deformation of the counterbrace 12 in the direction and greatly improving the stability of the counterbrace 12. In addition, because the newly added steel pipe piles 31 are constructed around the original pile structure, the part of the steel pipe piles 31 in the formed second column 4 can clamp the pile foundation 22 of the first column 2 and the earth, form a larger cross-sectional diameter, and provide larger bearing capacity. Moreover, the steel pipe piles 31 clamp the earth inside to form an earth column, thereby reducing the manufacturing cost required for manufacturing a large-diameter column.

[0040] Specifically, the connecting assembly 5 comprises a clamp 51, and the extension part 3 is sequentially and spacedly sleeved with a plurality of clamps 51 from top to bottom. The height of the lowermost clamp 51 is higher than the second predetermined depth. The specific structure of each clamp 51 comprises a retractable clamp body and a locking bolt. When the clamp body is sleeved on the extension part 3 and the locking bolt is tightened, the clamp is positioned on the extension part 3. Then, the clamp 51 is completely fixed on the extension part 3. The clamp 51 is sleeved on the plurality of steel pipe piles 31 of the extension part 3, so that the end of the plurality of steel pipe piles 31 away from the earth can better clamp the pile foundation 22 in the middle, thereby improving the structural stability of the entire second column 4 and providing stable support for the counterbrace 12.

[0041] In the embodiment, the specific method for completely fixing the clamp 51 on the extension part 3 is that the clamp 51 is directly welded and fixed with the steel pipe pile 31 contacted after being retracted. Because the steel pipe pile 31 is made of metal material, the clamp 51 can be directly welded on the steel pipe pile 31. The fixing method is relatively simple and convenient for the construction personnel to operate.

[0042] Because there is a difference in cross-sectional diameter between the first column 2 and the extension 3 formed by the steel pipe pile 31, in order to enable the extension 3 with a larger cross-sectional diameter to support the first column 2 with a smaller cross-sectional diameter, with reference to Figure 5 , a plurality of diagonal braces 6 are arranged on the connecting portion 21 in the circumferential direction, one end of the plurality of diagonal braces 6 away from the connecting portion 21 is connected to the top of the extension 3, the diagonal brace 6 is connected to the connecting portion 21 and the extension 3 at the same time, forming a stable triangular attitude, so that the extension 3 with a larger cross-sectional diameter can support the connecting portion 21 with a smaller cross-sectional diameter in the circumferential direction, further improving the overall structural stability of the second column 4.

[0043] Specifically, the fixing scheme of the diagonal brace 6 and the connecting portion 21 needs to be determined according to the construction method of the first column 2. In this embodiment, the first column 2 can be constructed in two forms. The first is a reinforced concrete bored pile. When this method is used for construction, the connecting portion 21 of the first column 2 needs to be broken by concrete, and then the diagonal brace 6 is welded and fixed with the longitudinal reinforcement of the first column 2. The second is a lattice column. The diagonal brace 6 is directly welded and fixed with the angle steel on the lattice column.

[0044] Because the steel pipe pile 31 is a hollow structure with a small edge cross-sectional area, it is difficult to stably connect the diagonal brace 6. Therefore, with reference to Figure 3 and Figure 6 , the column lengthening structure in the present application further comprises an end cover 7, the end cover 7 is arranged on the extension 3, the end cover 7 is provided with a position avoiding hole for the connecting portion 21 to extend out, one end of the plurality of diagonal braces 6 away from the connecting portion 21 is connected to the end cover 7, the end cover 7 is installed on the extension 3, thereby closing the end of the hollow steel pipe pile 31, and further forming a platform above the end cover 7 that can be used for construction, the end of the diagonal brace 6 away from the column is fixed on the end cover 7, thereby improving the connection stability between the diagonal brace 6 and the extension 3.

[0045] Specifically, the end cover 7 is directly welded to the steel pipe pile 31 of the extension 3 to realize the fixation of the end cover 7.

[0046] After the end cover 7 is installed on the extension 3, in order to fix the connecting portion 21 of the steel structure and the end cover 7, with reference to Figure 6 , a connecting rib 8 extending in the horizontal direction is arranged on the connecting portion 21, the connecting rib 8 is made of steel, both ends of the connecting rib 8 extend out of the connecting portion 21, and both ends of the connecting rib 8 are welded and fixed with the end cover 7. In this way, the connecting rib 8 serves as a bridge for connecting the end cover 7 and the connecting portion 21, and then the lower end of the connecting portion 21 and the upper end of the extension 3 are connected through the end cover 7 and the connecting rib 8, thereby improving the overall structural stability of the second column 4 formed by the combination of various components.

[0047] Specifically, the connecting rib 8 is provided with two, the two connecting ribs 8 are horizontally perpendicular to each other, and the connecting rib can be welded and fixed with the connecting part 21, thereby improving the connection stability with the connecting part 21.

[0048] In order to speed up the construction progress and timely install the end cover 7 to the extension part 3, referring to Figure 3 and Figure 6 , the end cover 7 comprises a sleeving part 71 and a cover part 72 connected with each other, the sleeving part 71 is sleeved on the extension part 3, and the cover part 72 comprises two semicircular ring plates 721 connected with each other, one of the semicircular ring plates 721 is provided with an avoiding slot on the side close to the other semicircular ring plate 721, the avoiding slots of the two semicircular ring plates 721 form an avoiding hole, and the semicircular ring plates 721 are both covered on the extension part 3.

[0049] As can be seen from the above, because the installation of the end cover 7 cannot be directly sleeved into the extension part 3 after the foundation pit 1 is excavated to the second predetermined depth and the extension part 3 has been connected with the pile foundation 22 of the first column 2, by adopting the technical scheme, a rectangular plate with a length of the circumference of the extension part 3 and a circular plate with a radius of the extension part 3 are cut from appropriate size steel, the rectangular plate is enclosed on the top of the extension part 3 to form the sleeving part 71, the circular plate is cut into two semicircular ring plates 721 with avoiding slots, the semicircular ring plates 721 are covered on the upper end of the extension part 3, the two semicircular ring plates 721 are welded and fixed, and the semicircular ring plates 721 and the sleeving part 71 are welded and fixed, so that the end cover 7 can be obtained, the scheme can quickly install the end cover 7 on the extension part 3, and the on-site steel can be used for local material, and the end cover 7 can be obtained only by cutting and welding on site, so that the construction personnel can quickly process.

[0050] Further, the diagonal brace 6 and the connecting rib 8 are arranged to avoid each other, so as to reduce the risk that the overall connection stability of the second column 4 is reduced due to mutual collision and damage of the two.

[0051] In order to increase the stability of the pile foundation 22, the depth of the bottom end of the pile foundation 22 is greater than the second predetermined depth, the length of the pile foundation 22 is limited to be able to extend into the earthwork of the foundation pit 1 excavated to the second predetermined depth, at this time, the pile foundation 22 still has contact with the earthwork of the foundation pit 1, and the pile foundation 22, the earthwork in the foundation pit 1 and the steel pipe pile 31 jointly form a three-layer laminated structure, the earthwork in the outermost layer clamps the steel pipe pile 31 and the pile foundation 22 of the first column 2 in turn, compared with the earthwork in the outermost layer clamping the steel pipe pile 31 and the earthwork in turn, the integrated pile foundation 22 has strong stability and will not cause the risk of loose earthwork leading to unstable overall structure, thereby strengthening the connection stability between the steel pipe pile 31 and the pile foundation 22.

[0052] In a second aspect, the application further provides a construction method applied to the column lengthening structure provided in the first aspect, and the construction method comprises the following steps: S1: constructing the side wall 11 at the predetermined position of the foundation pit 1, and sequentially constructing the first column 2 and the extension part 3.

[0053] Specifically, first, the size of the predetermined position of the foundation pit 1 is determined by measurement and lofting, and the support piles are sequentially constructed at the boundary of the predetermined position of the foundation pit 1. The multiple support piles at each side wall of the foundation pit 1 form the side wall 11. Then, the earthwork at the predetermined position of the first column 2 is excavated and the reinforcement cage is placed. The hole depth of the first column 2 is greater than the first predetermined depth. If a lattice column is used, the lattice column is welded with the reinforcement cage and then placed into the hole. Finally, the concrete is poured, and the first column 2 is formed after the concrete solidifies. After receiving the new design scheme and the design depth of the foundation pit 1 in the new design scheme is greater than the original design depth, the construction of the strut 12 is stopped, and multiple steel pipe piles 31 are installed around the first column 2. It is ensured that the two adjacent steel pipe piles 31 can abut against each other. The low end depth of each steel pipe pile 31 is greater than the second predetermined depth, which meets the length requirement of the column after the design is changed.

[0054] S2: installing the strut 12 and connecting the strut 12 to the first column 2.

[0055] Specifically, the two ends of the strut 12 are connected to the two opposite side walls 11 of the foundation pit 1, respectively, and then the strut 12 is welded and fixed to the connecting part 21 of the first column 2.

[0056] S3: excavating the earthwork of the foundation pit 1 until the first predetermined depth, and connecting the extension part 3 to the first column 2.

[0057] Specifically, as described in the column lengthening structure provided in the first aspect, after the earthwork of the foundation pit 1 is excavated to the first predetermined depth, the end of the extension part 3 is exposed. The end cap 7 is fixedly installed on the steel pipe pile 31 of the extension part 3. The connecting rib 8 is arranged on the connecting part 21 and connected to the end cap 7. Finally, one end of the inclined strut 6 is fixedly connected to the connecting part 21, and the other end is connected to the end cap 7, so as to complete the connection between the end part of the extension part 3 and the first column 2.

[0058] S4: continuing to excavate the earthwork of the foundation pit 1 until the second predetermined depth, and then laying the bottom plate at the bottom of the foundation pit 1.

[0059] Specifically, after excavation, the steel pipe pile 31 of the extension part 3 gradually exposes. At this time, the clamp 51 is installed on the gradually exposed pile. After the clamp 51 is tightened, the body of the clamp 51 is welded on the steel pipe pile 31, so as to completely fix the steel pipe pile 31. Then, multiple clamps 51 are sequentially installed and welded on the extension part 3 during the process of gradually excavating the earthwork of the foundation pit 1 to the second predetermined depth.

[0060] As can be seen from the above, when the excavation continues between the first predetermined depth and the second predetermined depth, the axial force of the column, which is larger than that of the original design, will be transferred to the newly constructed steel pipe pile 31. In turn, the increased force will be transferred to the deeper soil layer through the steel pipe pile 31, which will make up for the problem of insufficient vertical bearing capacity of the first column 2 pile foundation 22 after the foundation pit 1 is deepened. The force can be smoothly transferred to the newly added structure, which will improve the stability of the bracing 12 in the foundation pit 1.

[0061] The preferred embodiments of the present invention have been described in detail above, but the present invention is not limited to the embodiments described. Those skilled in the art can make various equivalent modifications or substitutions without departing from the spirit of the present invention, and these equivalent modifications or substitutions are all included within the scope defined by the claims of this application.

Claims

1. A column extension structure, characterized in that, include: A brace (12) extends in a direction parallel to the horizontal, and the two ends of the brace (12) are respectively connected to the side walls (11) on opposite sides of the foundation pit (1) used to cooperate with the column extension structure. The first column (2) is located in the middle of the foundation pit (1). The first column (2) includes a connecting part (21) and a pile foundation (22) connected from top to bottom. The end of the connecting part (21) away from the pile foundation (22) is connected to the bracing (12). The pile foundation (22) is buried in the soil of the foundation pit (1) and its bottom end is at a depth lower than the first predetermined depth of the foundation pit (1). The extension (3) includes a steel pipe pile (31) extending in the vertical direction. The steel pipe pile (31) is buried in the soil of the foundation pit (1). The depth of the top of the steel pipe pile (31) is higher than the depth of the bottom of the pile foundation (22). The depth of the bottom of the steel pipe pile (31) is lower than the second predetermined depth of the foundation pit (1). The second predetermined depth is lower than the first predetermined depth. The steel pipe pile (31) is connected to the pile foundation (22). The steel pipe pile (31) and the first column (2) are connected to form a second column (4).

2. The column extension structure according to claim 1, characterized in that, The extension (3) includes a plurality of steel pipe piles (31), which are arranged circumferentially along the pile foundation (22). The plurality of steel pipe piles (31) abut against the pile foundation (22). The column extension mechanism also includes a connecting component (5) for connecting the pile foundation (22) and the plurality of steel pipe piles (31).

3. The column extension structure according to claim 2, characterized in that, The connecting component (5) includes clamps (51), and the extension (3) is provided with a plurality of clamps (51) arranged at intervals from top to bottom, with the lowest clamp (51) being at a height higher than the second predetermined depth.

4. The column extension structure according to claim 2, characterized in that, The connecting part (21) is provided with a plurality of diagonal braces (6) along the circumferential direction, and one end of the plurality of diagonal braces (6) away from the connecting part (21) is connected to the top of the extension part (3).

5. The column extension structure according to claim 4, characterized in that, It also includes an end cap (7), which covers the extension (3). The end cap (7) has a clearance hole for the connecting part (21) to extend out. The ends of the plurality of diagonal braces (6) away from the connecting part (21) are all connected to the end cap (7).

6. The column extension structure according to claim 5, characterized in that, The connecting part (21) is provided with a connecting rib (8) extending in a direction parallel to the horizontal direction. Both ends of the connecting rib (8) extend out of the connecting part (21), and the ends of the connecting rib (8) are connected to the end cap (7).

7. The column extension structure according to claim 5, characterized in that, The end cap (7) includes a fitting part (71) and a cover part (72) connected to each other. The fitting part (71) is fitted onto the extension part (3). The cover part (72) includes two interconnected semi-circular ring plates (721). One of the semi-circular ring plates (721) has a relief groove on the side near the other semi-circular ring plate (721). The relief grooves of the two semi-circular ring plates (721) form the relief hole. The semi-circular ring plates (721) are both covered on the extension part (3).

8. The column extension structure according to claim 5, characterized in that, The depth of the bottom end of the pile foundation (22) is greater than the second predetermined depth.

9. A construction method applied to a column extension structure as described in any one of claims 1-8, characterized in that, The construction method includes: Construct the side wall (11) at the predetermined position in the foundation pit (1), and construct the first column (2) and the extension (3) in sequence; Install the bracing (12) and connect the bracing (12) to the first column (2); Excavate the foundation pit (1) to the first predetermined depth, and connect the extension (3) to the first column (2); Continue excavating the foundation pit (1) until the second predetermined depth.

10. A construction method according to claim 9, characterized in that, The continued excavation of the foundation pit (1) to the second predetermined depth includes: excavating the soil and fitting the clamp (51) onto the extension (3).

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