CN112323811A - Adjustable-length inner supporting structure of fabricated foundation pit and construction method of adjustable-length inner supporting structure - Google Patents

Abstract

The invention belongs to the technical field of underground foundation pit engineering, and particularly relates to an adjustable-length inner support structure of an assembly type foundation pit and a construction method thereof, wherein the adjustable-length inner support structure comprises an enclosure structure and an assembly type support; the top of the enclosure structure is provided with a crown beam, the inner side of the enclosure structure is provided with a waist beam, and the assembled supports are supported between two opposite sides of the crown beam and between two opposite sides of the waist beam; embedded parts are embedded in the crown beam or the waist beam, one end of the assembled support is connected with the embedded part on one side of the assembled support, and the other end of the assembled support is connected with the embedded part on one side of the assembled support through a telescopic structure; and a jack is also supported between the other end of the assembled support and the embedded part on one side of the assembled support, and the jack is electrically connected with the control system. The invention can adjust the length of the end joint through the telescopic structure, thereby adjusting the construction error; meanwhile, the requirements of repeated loading for prestress loss and support relaxation can be met.

Description

Adjustable-length inner supporting structure of fabricated foundation pit and construction method of adjustable-length inner supporting structure

Technical Field

The invention belongs to the technical field of underground foundation pit engineering, and particularly relates to an adjustable-length inner support structure of an assembly type foundation pit and a construction method thereof.

Background

Traditional cast in situ concrete supports, because of its rigidity is big, the wholeness is good, advantages such as safe and reliable, generally apply to underground works, nevertheless also have outstanding problem and shortcoming: (1) cost, high investment: concrete support belongs to temporary engineering, a main body of a station structure is finished, namely outward transportation is broken, the investment of temporary waste engineering is high, generally, underground stations are millions, complex stations are tens of millions, and the cost of complex stations is tens of millions; (2) time-consuming and long construction period: supporting a formwork by concrete, binding reinforcing steel bars, pouring and vibrating, maintaining and removing at the later stage, wherein the whole process is long for several months, and the site construction progress is seriously restricted; (3) hard, the degree of difficulty is big: the concrete support construction difficulty is high, and a large amount of manpower and material resources are consumed to break the construction after the use; (4) the concrete is not environment-friendly, the waste residues of the concrete are broken to pollute the environment, and the development direction of green construction, environmental protection and energy conservation is not met. Advanced products and scientific construction methods are urgently needed to replace the traditional concrete support.

In the existing prefabricated support, weak links are more at the connecting structure, and rigid connection cannot be realized at nodes, so that the overall stability of a foundation pit is insufficient; and the support may have a stress relaxation site in the use process, which causes local instability of the foundation pit and causes the damage of the whole foundation pit.

Disclosure of Invention

In order to overcome the defects in the prior art, the invention aims to provide an adjustable-length inner support structure of an assembly type foundation pit and a construction method thereof, which can adjust the length of an end joint and meet the requirements of repeated loading for prestress loss and support relaxation.

In order to achieve the purpose, the technical scheme of the invention is that the adjustable-length inner support structure of the fabricated foundation pit comprises an enclosure structure and a fabricated support; the top of the enclosure structure is provided with a crown beam, the inner side of the enclosure structure is provided with a waist beam, and the assembled supports are supported between two opposite sides of the crown beam and between two opposite sides of the waist beam; embedded parts are embedded in the crown beam or the waist beam, one end of the assembled support is connected with the embedded part on one side of the assembled support, and the other end of the assembled support is connected with the embedded part on one side of the assembled support through a telescopic structure; and a jack is also supported between the other end of the assembled support and the embedded part on one side of the assembled support, and the jack is electrically connected with the control system.

Furthermore, the telescopic structure comprises a first telescopic joint and a second telescopic joint, the first telescopic joint and the second telescopic joint are respectively connected with the assembled support and the embedded part and have the same structure, and the first telescopic joint and the second telescopic joint respectively comprise a solid steel plate, a U-hole steel plate, a U-shaped steel plate and a stiffening plate; one end of the U-shaped steel plate penetrates through a U-shaped hole in the U-shaped hole steel plate and is welded with the solid steel plate, and a plurality of rows of long round holes are formed in two side walls of the other end of the U-shaped steel plate; the solid steel plate is connected with the U-hole steel plate through a stiffening plate, and the side wall of the U-shaped steel plate is welded with the U-hole steel plate; the U-shaped steel plate of the first expansion joint is clamped in the U-shaped steel plate of the second expansion joint, and the long circular hole in the first expansion joint is connected with the long circular hole in the second expansion joint through a bolt; and the front end and the rear end of the jack are respectively propped against the solid steel plate of the first expansion joint and the solid steel plate of the second expansion joint.

Furthermore, the fabricated support is formed by splicing a plurality of prefabricated support sections, and each prefabricated support section comprises a steel pipe, an inner ring plate and an outer ring plate; the end faces of two ends of the steel pipe are welded with inner ring plates, and the outer walls of two ends of the steel pipe are welded with outer ring plates in an annular mode; a plurality of screw holes are formed in the inner ring plate and the outer ring plate at intervals in the circumferential direction, and the screw holes in the inner ring plate and the screw holes in the outer ring plate are in one-to-one correspondence; and corresponding screw holes on the inner ring plate and the outer ring plate on the adjacent prefabricated support sections are respectively provided with a screw and are fixed through nuts.

Furthermore, a plurality of screw holes are formed in the solid steel plate and the U-hole steel plate at intervals along the circumferential direction, and the screw holes in the inner ring plate, the outer ring plate, the solid steel plate and the U-hole steel plate are in one-to-one correspondence; and the inner ring plate and the outer ring plate on the prefabricated support section at the end part and corresponding screw holes on the solid steel plate and the U-hole steel plate on the first expansion joint are respectively provided with a screw and are fixed through nuts.

Furthermore, filling concrete is poured in the steel pipe, and a hollow part which penetrates through the filling concrete along the axial direction is formed in the filling concrete; the terminal surface at steel pipe both ends all welds the shrouding, interior crown plate welds in deviate from on the shrouding on the one side of steel pipe.

Furthermore, a plurality of circumferential stirrups and a plurality of longitudinal reinforcements are arranged in the filling concrete, the circumferential stirrups are arranged at intervals along the supporting direction, the longitudinal reinforcements are arranged at intervals along the inner sides of the circumferential stirrups, the longitudinal reinforcements are connected with the circumferential stirrups, and two ends of the longitudinal reinforcements are connected with the sealing plates at two ends of the steel pipe through perforated plug welding respectively.

Furthermore, the inner ring plate and the outer ring plate which are positioned at the same end of the steel pipe are connected through a plurality of stiffening ribs, the stiffening ribs are welded with the steel pipe, and the stiffening ribs and the screw rods are arranged at intervals.

Furthermore, the stiffening rib is a chamfered rectangular steel plate, and two corners of the side edge connected with the steel pipe on the stiffening rib are chamfers.

Furthermore, the embedded part comprises an embedded steel plate and a plurality of embedded screws; one ends of the embedded screws respectively penetrate through the embedded steel plates in sequence, and the other ends of the embedded screws extend out of the crown beam or the waist beam and respectively penetrate through the plurality of screw holes in the solid steel plate of the second expansion joint and the plurality of screw holes in the U-hole steel plate in sequence and then are fixed through nuts or respectively penetrate through the plurality of screw holes in the inner ring plate of the assembled support end part and the plurality of screw holes in the outer ring plate in sequence and then are fixed through nuts.

The invention also provides a construction method of the adjustable-length inner support structure of the fabricated foundation pit, which comprises the following steps:

s1, manufacturing the prefabricated support sections, the embedded parts, the first expansion joints and the second expansion joints in a factory according to a design drawing, and transporting to a construction site;

s2, splicing and assembling the prefabricated support segments section by section through a screw and a screw cap to form an assembled support; connecting the first expansion joint with a prefabricated support section at one end of the assembled support through a screw and a nut;

s3, placing the embedded part at a support design position in the crown beam or the waist beam to be poured, and then pouring the crown beam or the waist beam to embed the embedded part therein;

s4, after the crown beam or the waist beam reaches the design strength, fixing a second expansion joint on an embedded screw extending out of an embedded part on one side through a nut;

s5, embedding a support at the supporting position in the foundation pit;

s6, hoisting the assembled support, placing the assembled support on a support, clamping the U-shaped steel plate of the first expansion joint in the U-shaped steel plate of the second expansion joint, and fixing the prefabricated support section at the other end of the assembled support with the embedded screw extending out of the embedded part at the other side through a nut;

s7, placing a jack in the U-shaped steel plate, and applying pressure to a designed value through a control system to enable two ends of the jack to be tightly propped against the solid steel plate of the first expansion joint and the solid steel plate of the second expansion joint respectively;

s8, inserting bolts into the oblong holes in the side walls of the U-shaped steel plate of the first expansion joint and the U-shaped steel plate of the second expansion joint, and screwing the bolts;

s9, after the construction is finished, the jack is loosened, the bolt and the nut are unscrewed, the expansion joint and the screw rod are removed, and the prefabricated support section is recovered.

Compared with the prior art, the invention has the following beneficial effects:

(1) one end of the assembled support is connected with an embedded part in the crown beam or the waist beam by adopting a telescopic structure, and the length of a joint at the end part can be adjusted by the telescopic structure, so that the construction error is adjusted; meanwhile, a jack is arranged, stress compensation is carried out in time when the stress relaxation phenomenon occurs in the use process of the assembled support, early warning is carried out in time when the stress is too large, and the damage to the whole foundation pit caused by local instability of the foundation pit is prevented;

(2) the U-shaped steel plate of the expansion joint penetrates through the U-shaped hole in the U-shaped hole steel plate and is welded with the U-shaped hole steel plate, and the stiffening plate is adopted to connect the solid steel plate and the U-shaped hole steel plate, so that the rigidity of the edge node is improved, and the safety of a foundation pit is ensured.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to the drawings without creative efforts.

Fig. 1 is a plan view of an adjustable-length inner support structure of a fabricated foundation pit according to an embodiment of the present invention;

FIG. 2 is a longitudinal cross-sectional view of a prefabricated support segment provided in accordance with an embodiment of the present invention;

FIG. 3 is a cross-sectional view of a prefabricated support section when a steel tubular is circular according to an embodiment of the present invention;

FIG. 4 is a cross-sectional view of a prefabricated support section with a square steel tube according to an embodiment of the present invention;

FIG. 5 is a cross-sectional view of a prefabricated support section with a round steel tube and without concrete fill according to an embodiment of the present invention;

FIG. 6 is a longitudinal cross-sectional view of a connecting node structure of prefabricated support segments provided in accordance with an embodiment of the present invention;

FIG. 7 is a cross-sectional view of a connecting node structure of prefabricated support sections provided in accordance with an embodiment of the present invention;

FIG. 8 is a schematic view of an inner ring plate when the steel pipe provided by the embodiment of the present invention is circular;

FIG. 9 is a schematic view of an outer ring plate when the steel pipe provided by the embodiment of the present invention is circular;

FIG. 10 is a schematic view of a stiffener according to an embodiment of the present invention;

FIG. 11 is a schematic view of a prefabricated support section coupled to a crown beam via a telescoping configuration in accordance with an embodiment of the present invention;

FIG. 12 is a side view of a first expansion joint and a second expansion joint provided by an embodiment of the present invention;

FIG. 13 is a schematic view of a solid steel plate provided in an embodiment of the present invention;

FIG. 14 is a schematic view of a U-hole steel plate according to an embodiment of the present invention;

FIG. 15 is a schematic view of a prefabricated support section directly coupled to a crown beam provided in accordance with an embodiment of the present invention;

FIG. 16 is a schematic view of an embedment provided in an embodiment of the present invention;

FIG. 17 is a cross-sectional view of a mount provided in accordance with an embodiment of the present invention;

FIG. 18 is a top view of a support provided in accordance with an embodiment of the present invention;

in the figure: 1. an enclosure structure; 2. a crown beam; 3. prefabricating a support segment; 4. embedding parts; 5. a first expansion joint; 6. a second expansion joint; 7. a support; 8. an outer ring plate; 9. a stiffening rib; 10. an inner ring plate; 11. a steel pipe; 12. hooping; 13. longitudinal ribs; 14. closing the plate; 15. plug welding of the through hole; 16. filling concrete; 17. a screw; 18. a nut; 19. a screw hole; 20. a solid steel plate; 21. a U-hole steel plate; 22. a U-shaped steel plate; 23. a long round hole; 24. a bolt; 25. a jack; 26. a wire; 27. a control system; 28. a water drain hole; 29. concave steel blocks; 30. steel legs; 31. a concrete base; 32. a stiffening plate; 33. pre-burying a steel plate; 34. and (4) pre-burying a screw.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

In the description of the present invention, it is to be understood that the terms "center", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", and the like indicate orientations or positional relationships based on those shown in the drawings, and are only for convenience of description and simplicity of description, and do not indicate or imply that the referenced devices or elements must have a particular orientation, be constructed and operated in a particular orientation, and thus, are not to be construed as limiting the present invention.

The terms "first", "second" and "first" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature; in the description of the present invention, "a plurality" means two or more unless otherwise specified.

Example one

As shown in fig. 1, 11 and 15, the present embodiment provides an adjustable length inner support structure for a fabricated foundation pit, which includes a building enclosure 1 and a fabricated support; the top of the enclosure structure 1 is provided with a crown beam 2, the inner side of the enclosure structure 1 is provided with a waist beam, and the assembled supports are supported between two opposite sides of the crown beam 2 and between two opposite sides of the waist beam; embedded parts 4 are embedded in the crown beam 2 or the waist beam, one end of the assembled support is connected with the embedded parts 4 on one side of the assembled support, and the other end of the assembled support is connected with the embedded parts 4 on one side of the assembled support through a telescopic structure; and a jack 25 is also supported between the other end of the assembled support and the embedded part 4 on one side of the assembled support, and the jack 25 is electrically connected with a control system 27. In the embodiment, one end of the assembled support is connected with the embedded part 4 in the crown beam 2 or the waist beam by adopting a telescopic structure, and the length of a joint at the end part can be adjusted by the telescopic structure, so that the construction error is adjusted; and meanwhile, the jack 25 is arranged, so that stress compensation can be timely carried out when the stress relaxation phenomenon occurs in the use process of the assembled support, early warning can be timely carried out when the stress is too large, and the damage to the whole foundation pit caused by local instability of the foundation pit can be prevented. The drawings of the present embodiment are explained taking the crown beam 2 as an example, and the case of the wale refers to the crown beam 2.

The jack 25 of the embodiment is an intelligent jack 25, has enough jacking force, can sense self stress and transmit the self stress to the control system 27 through the lead 26, and the control system 27 makes corresponding response according to the stress to adjust the jacking force and the elongation to form an intelligent stress compensation device which can construct prestress according to needs and meet the requirements of repeated loading on prestress loss and support relaxation; the jack 25 should not be oversized to avoid interfering with the connection of the telescoping structures.

Further, as shown in fig. 11 to 14, the telescopic structure includes a first expansion joint 5 and a second expansion joint 6, and the first expansion joint 5 and the second expansion joint 6 are respectively connected to the fabricated support and the embedded part 4 and have the same structure, and each of the first expansion joint 5 and the second expansion joint comprises a solid steel plate 20, a U-hole steel plate 21, a U-shaped steel plate 22 and a stiffener plate 32; one end of the U-shaped steel plate 22 penetrates through a U-shaped hole in the U-shaped hole steel plate 21 and is welded with the solid steel plate 20, and a plurality of rows of long round holes 23 are formed in two side walls of the other end of the U-shaped steel plate; the solid steel plate 20 is connected with the U-hole steel plate 21 through a stiffening plate 32, and the side wall of the U-shaped steel plate 22 is welded with the U-hole steel plate 21; the U-shaped steel plate 22 of the first expansion joint 5 is clamped in the U-shaped steel plate 22 of the second expansion joint 6, and the long circular hole 23 in the first expansion joint 5 is connected with the long circular hole 23 in the second expansion joint 6 through a bolt 24; the front end and the rear end of the jack 25 are respectively pressed against the solid steel plate 20 of the first expansion joint 5 and the solid steel plate 20 of the second expansion joint 6. The U-shaped steel plate 22 of this embodiment is provided with a plurality of rows of long round holes 23, and the long round holes 23 are arranged along the supporting direction, the long round holes 23 on the first expansion joint 5 are connected with the long round holes 23 on the second expansion joint 6 through bolts 24, the end part of the assembled support and the crown beam 2 or waist beam node adopt the variable-length round hole 23 steel box slot node, the rigid connection and equal-strength connection requirements of the edge node can be met, the engineering safety and the detachability of the end part node are ensured, the prefabricated part can be conveniently recycled, meanwhile, the length of the joint can be changed by adjusting the relative position of the long round holes 23 according to the requirements, and therefore the construction error can be adjusted.

Optimally, drain holes 28 are reserved in the bottom plate of the U-shaped steel plate to prevent rainwater in the U-shaped space where the jack 25 is located from accumulating and damaging the jack 25; meanwhile, the size of the water drainage hole 28 is not required to be too large, so that the steel plate at the joint is prevented from being weakened.

In this embodiment, the size of the U-shaped steel plate 22 of the first expansion joint 5 is smaller than the size of the U-shaped steel plate 22 of the second expansion joint 6, so that the U-shaped steel plate 22 of the first expansion joint 5 can be properly clamped in the U-shaped steel plate 22 of the second expansion joint 6 to form a U-shaped groove, but the oblong holes 23 in the U-shaped steel plate 22 of the first expansion joint 5 and the oblong holes 23 in the U-shaped steel plate 22 of the second expansion joint 6 need to be at the same height and have the same distance; in addition, the U-shaped hole on the U-shaped hole steel plate 21 is matched with the ruler of the U-shaped steel plate 22, the U-shaped steel plate 22 penetrates through the U-shaped hole on the U-shaped hole steel plate 21 and is welded with the U-shaped hole steel plate 21, meanwhile, a plurality of stiffening plates 32 which are arranged along the outer wall of the U-shaped steel plate 22 at intervals are adopted to connect the solid steel plate 20 and the U-shaped hole steel plate 21, the inner sides of the stiffening plates 32 are welded with the U-shaped steel plate 22, the rigidity of the connecting node is improved, the integrity, the rigidity and the bearing capacity which are the same as or similar to those of cast-in-place concrete support are ensured by the.

In this embodiment, the fabricated support is formed by splicing a plurality of prefabricated support sections 3, wherein the prefabricated support sections 3 may be supported by concrete through hollow steel tubes 11, may also be supported by pure steel and pure concrete, or may also be supported by high-strength alloy steel materials or combined materials with concrete; the prefabricated support sections 3 can be designed with a plurality of fixed module sections with proper lengths according to requirements, and are not suitable for overlong, hoisting construction is not suitable for overlong, and joints are too many and difficult to connect due to too short length; as an implementation mode, the prefabricated support sections 3 can be designed with standard modules of 4m, 5m, 6m and the like and end section modules of 2m, and the prefabricated support sections 3 with completely the same, incompletely the same or completely different length specifications are selected for assembly according to actual foundation pit requirements, so that the requirements of foundation pit supports with different widths and lengths are met, and the universal applicability is realized.

As an embodiment, the prefabricated support segment 3 comprises a steel tube 11, an inner ring plate 10 and an outer ring plate 8; inner ring plates 10 are welded on the end faces of two ends of the steel pipe 11, and outer ring plates 8 are welded on the outer walls of two ends of the steel pipe 11 in an annular mode; a plurality of screw holes 19 are formed in the inner ring plate 10 and the outer ring plate 8 at intervals in the circumferential direction, and the screw holes 19 in the inner ring plate 10 and the outer ring plate 8 are in one-to-one correspondence; the corresponding screw holes 19 on the inner ring plate 10 and the outer ring plate 8 on the adjacent prefabricated support sections 3 are respectively provided with screws 17 and fixed through nuts 18. As shown in fig. 2 and 6, the prefabricated support segments 3 of the present embodiment are connected by a plurality of screws 17, so as to ensure rigid connection of the intermediate nodes, realize equal strength of the nodes and the members, ensure safety and stability of the foundation pit engineering, facilitate installation and disassembly, and facilitate industrial manufacture and large-area popularization and application; during splicing, a plurality of screw holes 19 on two prefabricated support sections 3 are respectively aligned, then screws 17 are installed in the screw holes 19 on the same straight line and are fixed through nuts 18, and splicing between the prefabricated support sections 3 is achieved.

Furthermore, a plurality of screw holes 19 are arranged on the solid steel plate 20 and the U-hole steel plate 21 at intervals along the circumferential direction, and the screw holes 19 on the inner ring plate 10, the outer ring plate 8, the solid steel plate 20 and the U-hole steel plate 21 are in one-to-one correspondence; the inner ring plate 10 and the outer ring plate 8 on the prefabricated support section 3 at the end and the corresponding screw holes 19 on the solid steel plate 20 and the U-hole steel plate 21 on the first expansion joint 5 are respectively provided with a screw 17 and fixed by a screw cap 18. As shown in fig. 11, the first expansion joint 5 of the present embodiment is connected to the prefabricated support segment 3 at the end portion through a plurality of screws 17, so as to ensure rigid connection of the connection node, realize equal strength of the node and the member, ensure safety and stability of the foundation pit engineering, and facilitate installation and disassembly; during splicing, the solid steel plate 20 and the U-hole steel plate 21 are respectively aligned with the plurality of screw holes 19 on the inner ring plate 10 and the outer ring plate 8, and then the screws 17 are arranged in the screw holes 19 on the same straight line and fixed through the nuts 18, so that the first expansion joint 5 is connected with the fabricated support.

As another embodiment, on the basis of the prefabricated support section 3 of the steel structure, filling concrete 16 is poured into the steel pipe 11, and a hollow part penetrating along the axial direction is formed in the filling concrete 16; seal plates 14 are welded to the end faces of two ends of the steel pipe 11, and the inner ring plate 10 is welded to one face, deviating from the steel pipe 11, of the seal plate 14. In the embodiment, the filling concrete 16 is poured in the steel pipe 11 to form a hollow structure, so that the advantages of the steel pipe 11 and the concrete can be fully exerted, the cost performance is high, and the concrete has obvious economic benefit compared with a pure steel support, and has higher rigidity compared with a concrete support, meanwhile, the steel pipe 11 is light and high in strength and convenient to recycle, transport and install, and the steel pipe 11 is an outer skin of a prefabricated support, so that the internal filling concrete 16 can be protected from being damaged, the repeated recycling of a prefabricated part is realized, and meanwhile, the bearing capacity of the filling concrete can be obviously improved under the hoop effect of the steel pipe 11, so that the bearing capacity (strength) of the concrete support of the hollow steel pipe 11 is high, the deformation resistance (rigidity) is high, the same strength and the rigidity as or even higher than those of the conventional concrete support can be achieved, and the engineering; and the hollow parts of the prefabricated support segments 3 of the assembled support are communicated, so that the assembled support has higher bearing capacity and stronger deformation resistance.

In this embodiment, the cross section of the steel pipe 11 may be circular, square, rectangular, polygonal, or the like, may be made of high-strength steel, may be made of alloy steel, or the like, satisfies the stress, and is easy to weld. In this embodiment, the filling concrete 16 may be high strength concrete, lightweight concrete or foam concrete, and the strength needs to meet the design requirement; the filling concrete 16 is hollow and can be formed by a centrifugal process or other processes, the thickness of the filling concrete 16 is about 100mm-200mm, and a small value is preferably adopted under the condition of meeting the supporting rigidity so as to reduce the self weight of the prefabricated part; the hollow part of the filling concrete 16 can be not provided with any inner wall, or can be in the form of an inner wall, the inner wall can be made of steel pipes, PVC and the like, the cross section of the inner wall is not limited to be circular, and can also be in various shapes such as square, polygon and the like, and the closing plate 14 can protect the filling concrete 16 at the end part; the closing plate 14, the inner ring plate 10, the outer ring plate 8, the stiffening ribs 9 and the steel pipes 11 can be prefabricated into a whole or can be prefabricated separately and then welded into a whole.

Furthermore, the sealing plate 14, the inner ring plate 10 and the outer ring plate 8 are all ring-shaped, and the inner ring size of the sealing plate 14 and the inner ring size of the inner ring plate 10 are all the same as the size of the hollow part of the filling concrete 16, and the inner ring size of the outer ring plate 8 is the same as the size of the outer ring of the steel pipe 11. The shapes and the sizes of the closing plate 14, the inner ring plate 10 and the outer ring plate 8 are matched with those of the steel pipe 11 in the embodiment; when the steel pipe 11 is circular, the closing plate 14, the inner ring plate 10 and the outer ring plate 8 are all circular steel plates, as shown in fig. 3 and 8-9, wherein the inner diameter of the outer ring plate 8 is the same as the outer diameter of the steel pipe 11, the inner diameter of the inner ring plate 10 and the inner diameter of the closing plate 14 are both the same as the inner diameter of the hollow part filled with concrete 16, the outer diameter of the closing plate 14 may be the same as the outer diameter of the steel pipe 11, and the outer diameter of the inner ring plate 10 may be the same as the outer diameter of the outer ring; when the steel pipe 11 is square, as shown in fig. 4, the closing plate 14, the inner ring plate 10 and the outer ring plate 8 are square ring-shaped steel plates, and the inner ring size and/or the outer ring size of the closing plate 14, the inner ring plate 10 and the outer ring plate 8 are adjusted accordingly, and will not be described in detail herein.

Furthermore, a plurality of circumferential stirrups 12 and a plurality of longitudinal reinforcements 13 are configured in the filling concrete 16, the circumferential stirrups 12 are arranged at intervals along the supporting direction, the longitudinal reinforcements 13 are arranged at intervals along the inner sides of the circumferential stirrups 12, each longitudinal reinforcement 13 is connected with the circumferential stirrups 12, and two ends of each longitudinal reinforcement 13 are connected with the sealing plates 14 at two ends of the steel pipe 11 through the perforated plug welds 15. As shown in fig. 2-4, a plurality of longitudinal bars 13 are disposed in the filling concrete 16 of this embodiment along the supporting direction, and the longitudinal bars 13 are uniformly disposed at the inner sides of the circumferential stirrups 12 and connected to the circumferential stirrups 12, so as to enhance the tight connection effect between the concrete and the steel tube 11, so as to ensure that the steel tube 11 and the concrete work together effectively, and the rigidity of the concrete is higher and far exceeds the concrete support of the concrete size; the diameters and the arrangement numbers of the longitudinal ribs 13 and the circumferential stirrups 12 can be determined according to actual conditions, and the longitudinal ribs and the circumferential stirrups can be arranged in the middle of the filling concrete 16; two ends of the longitudinal rib 13 are respectively welded with the sealing plates 14 at two ends of the steel pipe 11 into a whole through the perforation plug welding 15, so that the structure of the steel pipe 11 and the core filling concrete are integrated, the integrity of the prefabricated part is improved, and the node rigidity is ensured.

Furthermore, the inner ring plate 10 and the outer ring plate 8 at the same end of the steel pipe 11 are connected by a plurality of stiffening ribs 9, the stiffening ribs 9 are welded with the steel pipe 11, and the stiffening ribs 9 and the screw rods 17 are arranged alternately. As shown in fig. 3 and 7, the inner ring plate 10, the stiffening ribs 9 and the outer ring plate 8 at the end of the steel pipe 11 form a boot beam node to increase the joint stiffness, wherein the outer ring plate 8 is welded to the steel pipe 11 in a circumferential direction, the inner side of the outer ring plate 8 is welded to the stiffening ribs 9, the inner side of the inner ring plate 10 is welded to the stiffening ribs 9, the steel pipe 11 and the sealing plate 14, and three sides of the stiffening ribs 9 are welded to the outer ring plate 8, the inner ring plate 10 and the steel pipe 11; the stiffening ribs 9 are arranged between the pairs of the screw holes 19 of the inner and outer ring plates, the number of the stiffening ribs 9 is consistent with that of the screw holes 19, the stiffening ribs 9 and the screws 17 are arranged alternately, the rigidity of a joint at a joint is ensured, and the boot beam nodes of the prefabricated support sections 3 are connected through the screws 17, so that the strength and the rigidity of the joint are improved; the thickness of the stiffening ribs 9 is determined according to the stress, and the surplus is reserved.

Furthermore, the stiffening rib 9 is a rectangular steel plate with a chamfer, and two corners of the side edge of the stiffening rib 9 connected with the steel pipe 11 are chamfers. As shown in fig. 6 and 10, in the present embodiment, a chamfer structure is formed by chamfering two corners of the side edges connecting the stiffening ribs 9 and the steel pipes 11, which effectively reduces stress concentration during welding; wherein, the side of the stiffening rib 9 facing away from the steel pipe 11 can be flush with the outer side of the outer ring plate 8. As shown in fig. 11, the stiffener 32 of the present embodiment has the same structure as the stiffener 9 and is slightly larger than the stiffener 9.

Furthermore, the embedded part 4 comprises two embedded steel plates 33 and a plurality of embedded screws 34; one end of each embedded screw 34 sequentially penetrates through the two embedded steel plates 33, and the other end of each embedded screw extends out of the crown beam 2 or the wale and sequentially penetrates through the plurality of screw holes 19 in the solid steel plate 20 and the plurality of screw holes 19 in the U-hole steel plate 21 of the second expansion joint 6 and then is fixed through the screw cap 18, or sequentially penetrates through the plurality of screw holes 19 in the inner ring plate 10 and the plurality of screw holes 19 in the outer ring plate 8 at the end part of the assembled support and then is fixed through the screw cap 18. As shown in fig. 11, 15 and 16, the two embedded steel plates 33 of the present embodiment are oppositely disposed and embedded in the crown beam 2 or the wale to perform an anchoring function; the two embedded steel plates 33 are provided with a plurality of screw holes 19 which are in one-to-one correspondence with the plurality of screw holes 19 on the inner ring plate 10, the outer ring plate 8, the solid steel plate 20 and the U-hole steel plate 21, one end of each embedded screw 34 correspondingly penetrates through the corresponding screw holes 19 on the two embedded steel plates 33 and is welded with the embedded steel plates 33, and the other end extends out of the crown beam 2 or the waist beam; and a plurality of embedded screws 34 of the embedded part 4 on one side of the foundation pit extend out of the crown beam 2 or the girt and correspondingly pass through a plurality of screw holes 19 on the solid steel plate 20 and a plurality of screw holes 19 on the U-hole steel plate 21 of the second expansion joint 6 and then are fixed through screw caps 18, and a plurality of embedded screws 34 of the embedded part 4 on the other side of the foundation pit extend out of the crown beam 2 or the girt and correspondingly pass through a plurality of screw holes 19 of the inner ring plate 10 on the prefabricated support section 3 at the assembly type support end part and a plurality of screw holes 19 on the outer ring plate 8 and then are fixed through screw caps 18.

In the embodiment, all steel structures such as the steel pipe 11, the inner ring plate 10, the outer ring plate 8, the solid steel plate 20, the U-shaped steel plate 22, the U-hole steel plate 21 and other parts which are directly contacted with the outside need to be coated with antirust materials in advance, so that the surface of the steel structures is prevented from being rusted and damaged, and the strength is prevented from being reduced; the nuts 18 are preferably two stacked to prevent loosening, and a backing plate may be provided under the nuts 18 as needed.

Example two

The embodiment provides a construction method of the adjustable-length inner support structure of the fabricated foundation pit, which includes the following steps:

s1, manufacturing the prefabricated support sections 3, the embedded parts 4, the first expansion joints 5 and the second expansion joints 6 in a factory according to a design drawing, and transporting to a construction site;

s2, splicing and assembling the prefabricated support sections 3 section by section through the screw rods 17 and the screw caps 18 to form an assembled support; and the first expansion joint 5 is connected with the prefabricated support section 3 at one end of the fabricated support through a screw rod 17 and a nut 18;

s3, placing the embedded part 4 at a support design position in the crown beam 2 or the waist beam to be cast, and then casting the crown beam 2 or the waist beam to embed the embedded part 4 therein;

s4, after the crown beam 2 or the waist beam reaches the designed strength, fixing the second expansion joint 6 on the embedded screw 34 extending out of the embedded part 4 on one side through the screw cap 18;

s5, embedding a support 7 at the supporting position in the foundation pit;

s6, hoisting the assembled support, placing the assembled support on a support 7, clamping the U-shaped steel plate 22 of the first expansion joint 5 in the U-shaped steel plate 22 of the second expansion joint 6, and fixing the prefabricated support section 3 at the other end of the assembled support with the embedded screw 34 extending out of the embedded part 4 at the other side through the screw cap 18;

s7, placing the jack 25 in the U-shaped steel plate 22, and applying pressure to a designed value through the control system 27 to enable two ends of the jack 25 to be tightly propped against the solid steel plate 20 of the first expansion joint 5 and the solid steel plate 20 of the second expansion joint 6 respectively;

s8, inserting bolts 24 into the oblong holes 23 in the side walls of the U-shaped steel plates 22 of the first expansion joint 5 and the U-shaped steel plates 22 of the second expansion joint 6, and screwing the bolts;

s9, after the construction is finished, the jack 25 is loosened, the bolt 24 and the nut 18 are unscrewed, the expansion joint and the screw 17 are removed, and the prefabricated support section 3 is recovered.

The first expansion joint 5 and the second expansion joint 6 of this embodiment pass through bolt 24 to be connected, first expansion joint 5 supports wherein prefabricated support segment 3 of one end through screw rod 17 with the assembled, second expansion joint 6 passes through buried screw 34 and nut 18 with built-in fitting 4 and is connected, prefabricated support segment 3 and the built-in fitting 4 that the assembled supported the other end pass through buried screw 34 and nut 18 to be connected, realize dismantling easily, therefore, after foundation ditch engineering construction finishes, loosen jack 25, dismantle the back can relax pressure after dismantling the bolt 24 of connecting first expansion joint 5 with second expansion joint 6 earlier, then dismantle screw rod 17 and nut 18, dismantle prefabricated support segment 3 one by one, and retrieve prefabricated support segment 3, and the cost is reduced. And the assembled support in the embodiment can be rigidly connected with the crown beam 2 or the waist beam, so that in the ultra-deep foundation pit, the assembled support can replace a plurality of traditional concrete supports, and the assembly rate is improved.

The specific method for manufacturing the prefabricated support section 3 in the factory in step S1 of this embodiment may be:

s11, preparing a steel pipe 11, a sealing plate 14, an inner ring plate 10 and an outer ring plate 8 according to a design drawing;

s12, arranging a hoop reinforcement 12 and a plurality of longitudinal reinforcements 13 in the steel pipe 11;

s13, respectively welding sealing plates 14 on the end surfaces of the two ends of the steel pipe 11, and respectively connecting the two ends of the longitudinal rib 13 with the sealing plates 14 on the two ends of the steel pipe 11 through the perforation plug welding 15;

s14, welding an inner ring plate 10 on one surface of the closing plate 14, which is far away from the steel pipe 11, circumferentially welding an outer ring plate 8 on the outer wall of the two ends of the steel pipe 11, and welding stiffening ribs 9 between the inner ring plate 10 and the outer ring plate 8; then pouring filling concrete 16 in the steel pipe 11 and reserving the hollow part to finish the manufacture of the concrete support prefabricated member of the hollow steel pipe 11; or pouring filling concrete 16 in the steel pipe 11 and reserving a hollow part, then welding an inner ring plate 10 on one surface of the closing plate 14, which is far away from the steel pipe 11, annularly welding outer ring plates 8 on the outer walls of two ends of the steel pipe 11, and welding stiffening ribs 9 between the inner ring plate 10 and the outer ring plates 8 to complete the manufacture of the concrete support prefabricated member of the hollow steel pipe 11.

In the embodiment, the concrete 16 can be poured and filled in the steel pipe 11 by adopting a centrifugal process, so that an internal hollow can be automatically formed, the steel pipe 11 can be used as an external template of the centrifugal process without being detached, and meanwhile, compared with the conventional cast-in-place vibration process, the centrifugal process is convenient for realizing high-strength concrete, and the concrete of the hollow steel pipe 11 has higher bearing capacity and deformation resistance and better durability; other processes may also be used to accomplish this.

In step S2 of this embodiment, when the prefabricated support segments 3 are spliced section by section, the inner ring plates 10 at the end portions of the two prefabricated support segments 3 are aligned, and then the screws 17 sequentially pass through the outer ring plate 8 and the inner ring plate 10 at the end portion of one of the prefabricated support segments 3, and the inner ring plate 10 and the outer ring plate 8 at the end portion of the other prefabricated support segment 3 and are fixed by the nuts 18, so as to splice the two prefabricated support segments 3; when the first expansion joint 5 is spliced with the prefabricated support section 3 at the end part, the screw hole 19 on the inner ring plate 10 at the end part of the prefabricated support section 3 is aligned with the screw hole 19 on the solid steel plate 20 of the first expansion joint 5, and then the screw 17 sequentially passes through the screw holes 19 on the outer ring plate 8 and the inner ring plate 10 at the end part of the prefabricated support section 3, the solid steel plate 20 of the first expansion joint 5 and the U-hole steel plate 21 and is fixed through the screw cap 18. In the embodiment, the support is not easy to be damaged due to the effect of the protective wall of the external steel pipe 11, the joints are connected by the high-strength screw rods 17, and the prefabricated support sections 3 can be recycled by removing the high-strength screw rods 17, so that the cost is reduced.

In step S4 of this embodiment, when the second expansion joint 6 is fixed to the embedded part 4, the screws 17 of the embedded part 4 are respectively fixed by the nuts 18 after sequentially passing through the screw holes 19 of the solid steel plate 20 and the screw holes 19 of the U-hole steel plate 21 of the second expansion joint 6.

The specific method for embedding the support 7 in step S6 of this embodiment is as follows: the concrete base 31 is constructed firstly, the steel legs 30 are embedded in the concrete base 31, and then the concave steel blocks 29 with the grooves on the upper surface are welded on the steel legs 30. As shown in fig. 17 and 18, the concave steel block 29 has a concave groove on its upper surface, and the concave groove matches with the profile of the steel pipe 11 of the prefabricated support section 3 to facilitate the installation of the fabricated support, serving as a temporary support. The support 7 of the embodiment can also adopt other structural forms, and can play a temporary supporting role for the assembled support; under the condition that each component of the support 7 can bear the self weight of the prefabricated support, the size of each component is as small as possible so as to reduce the self weight.

The above description is only for the purpose of illustrating the preferred embodiments of the present invention and is not to be construed as limiting the invention, and any modifications, equivalents, improvements and the like that fall within the spirit and principle of the present invention are intended to be included therein.

Claims (10)

1. The utility model provides an adjustable length inner supporting structure of assembled foundation ditch which characterized in that: comprises an enclosure structure and an assembled support; the top of the enclosure structure is provided with a crown beam, the inner side of the enclosure structure is provided with a waist beam, and the assembled supports are supported between two opposite sides of the crown beam and between two opposite sides of the waist beam; embedded parts are embedded in the crown beam or the waist beam, one end of the assembled support is connected with the embedded part on one side of the assembled support, and the other end of the assembled support is connected with the embedded part on one side of the assembled support through a telescopic structure; and a jack is also supported between the other end of the assembled support and the embedded part on one side of the assembled support, and the jack is electrically connected with the control system.

2. The adjustable length internal support structure of a fabricated foundation pit according to claim 1, wherein: the telescopic structure comprises a first telescopic joint and a second telescopic joint, the first telescopic joint and the second telescopic joint are respectively connected with the assembled support and the embedded part and have the same structure, and the first telescopic joint and the second telescopic joint respectively comprise a solid steel plate, a U-hole steel plate, a U-shaped steel plate and a stiffening plate; one end of the U-shaped steel plate penetrates through a U-shaped hole in the U-shaped hole steel plate and is welded with the solid steel plate, and a plurality of rows of long round holes are formed in two side walls of the other end of the U-shaped steel plate; the solid steel plate is connected with the U-hole steel plate through a stiffening plate, and the side wall of the U-shaped steel plate is welded with the U-hole steel plate; the U-shaped steel plate of the first expansion joint is clamped in the U-shaped steel plate of the second expansion joint, and the long circular hole in the first expansion joint is connected with the long circular hole in the second expansion joint through a bolt; and the front end and the rear end of the jack are respectively propped against the solid steel plate of the first expansion joint and the solid steel plate of the second expansion joint.

3. The adjustable length internal support structure of a fabricated foundation pit as claimed in claim 2, wherein: the assembled support is formed by splicing a plurality of prefabricated support sections, and each prefabricated support section comprises a steel pipe, an inner ring plate and an outer ring plate; the end faces of two ends of the steel pipe are welded with inner ring plates, and the outer walls of two ends of the steel pipe are welded with outer ring plates in an annular mode; a plurality of screw holes are formed in the inner ring plate and the outer ring plate at intervals in the circumferential direction, and the screw holes in the inner ring plate and the screw holes in the outer ring plate are in one-to-one correspondence; and corresponding screw holes on the inner ring plate and the outer ring plate on the adjacent prefabricated support sections are respectively provided with a screw and are fixed through nuts.

4. The adjustable length internal support structure of a fabricated foundation pit according to claim 3, wherein: a plurality of screw holes are formed in the solid steel plate and the U-hole steel plate at intervals in the circumferential direction, and the screw holes in the inner ring plate, the outer ring plate, the solid steel plate and the U-hole steel plate are in one-to-one correspondence; and the inner ring plate and the outer ring plate on the prefabricated support section at the end part and corresponding screw holes on the solid steel plate and the U-hole steel plate on the first expansion joint are respectively provided with a screw and are fixed through nuts.

5. The adjustable length internal support structure of a fabricated foundation pit according to claim 3, wherein: filling concrete is poured in the steel pipe, and a hollow part which penetrates through the filling concrete along the axial direction is formed in the filling concrete; the terminal surface at steel pipe both ends all welds the shrouding, interior crown plate welds in deviate from on the shrouding on the one side of steel pipe.

6. The adjustable length internal support structure of a fabricated foundation pit according to claim 5, wherein: the filling concrete is internally provided with a plurality of circumferential stirrups and a plurality of longitudinal reinforcements, the circumferential stirrups are arranged at intervals along the supporting direction, the longitudinal reinforcements are arranged at intervals along the inner sides of the circumferential stirrups, the longitudinal reinforcements are connected with the circumferential stirrups, and the two ends of the longitudinal reinforcements are respectively connected with the sealing plates at the two ends of the steel pipe through perforated plug welding.

7. The adjustable length internal support structure of a fabricated foundation pit according to claim 3, wherein: the inner ring plate and the outer ring plate which are positioned at the same end of the steel pipe are connected through a plurality of stiffening ribs, the stiffening ribs are welded with the steel pipe, and the stiffening ribs and the screw rods are arranged alternately.

8. The adjustable length internal support structure of a fabricated foundation pit according to claim 7, wherein: the stiffening rib is a chamfered rectangular steel plate, and two corners of the side edge connected with the steel pipe on the stiffening rib are chamfers.

9. The adjustable length internal support structure of a fabricated foundation pit according to claim 4, wherein: the embedded part comprises an embedded steel plate and a plurality of embedded screws; one ends of the embedded screws respectively penetrate through the embedded steel plates in sequence, and the other ends of the embedded screws extend out of the crown beam or the waist beam and respectively penetrate through the plurality of screw holes in the solid steel plate of the second expansion joint and the plurality of screw holes in the U-hole steel plate in sequence and then are fixed through nuts or respectively penetrate through the plurality of screw holes in the inner ring plate of the assembled support end part and the plurality of screw holes in the outer ring plate in sequence and then are fixed through nuts.

10. A construction method of an adjustable length internal support structure of an assembly pit according to any one of claims 1 to 9, comprising the steps of:

s1, manufacturing the prefabricated support sections, the embedded parts, the first expansion joints and the second expansion joints in a factory according to a design drawing, and transporting to a construction site;

s2, splicing and assembling the prefabricated support segments section by section through a screw and a screw cap to form an assembled support; connecting the first expansion joint with a prefabricated support section at one end of the assembled support through a screw and a nut;

s3, placing the embedded part at a support design position in the crown beam or the waist beam to be poured, and then pouring the crown beam or the waist beam to embed the embedded part therein;

s4, after the crown beam or the waist beam reaches the design strength, fixing a second expansion joint on an embedded screw extending out of an embedded part on one side through a nut;

s5, embedding a support at the supporting position in the foundation pit;

s6, hoisting the assembled support, placing the assembled support on a support, clamping the U-shaped steel plate of the first expansion joint in the U-shaped steel plate of the second expansion joint, and fixing the prefabricated support section at the other end of the assembled support with the embedded screw extending out of the embedded part at the other side through a nut;

s7, placing a jack in the U-shaped steel plate, and applying pressure to a designed value through a control system to enable two ends of the jack to be tightly propped against the solid steel plate of the first expansion joint and the solid steel plate of the second expansion joint respectively;

s8, inserting bolts into the oblong holes in the side walls of the U-shaped steel plate of the first expansion joint and the U-shaped steel plate of the second expansion joint, and screwing the bolts;

s9, after the construction is finished, the jack is loosened, the bolt and the nut are unscrewed, the expansion joint and the screw rod are removed, and the prefabricated support section is recovered.

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