CN112323810A - Foundation pit inner support structure capable of being vertically positioned and adjusted and construction method - Google Patents

Abstract

The invention belongs to the technical field of underground foundation pit engineering, and particularly relates to a foundation pit inner support structure capable of being vertically positioned and adjusted and a construction method, wherein the foundation pit inner support structure comprises an enclosure structure, a support member and a vertical adjusting and positioning device for supporting and adjusting the vertical position of the support member; 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 supporting members 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, vertical adjusting and positioning devices are fixed on two opposite side walls of the enclosure structure, and two ends of the supporting member are respectively supported on the vertical adjusting and positioning devices on the two sides and connected with the embedded parts on the two sides. According to the invention, the vertical adjusting and positioning device is fixed on the enclosure structure, so that the vertical position of the supporting member can be accurately positioned according to different over-excavation depths and supporting vertical elevations, the construction error can be adjusted at any time, the vertical accurate construction is realized, and meanwhile, temporary support is provided for the supporting member in the construction process.

Description

Foundation pit inner support structure capable of being vertically positioned and adjusted and construction method

Technical Field

The invention belongs to the technical field of underground foundation pit engineering, and particularly relates to a foundation pit inner support structure capable of being vertically positioned and adjusted and a construction method.

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, rigid connection cannot be realized at nodes, integrity is poor, and the integral stability of a foundation pit is insufficient; and usually, the support is required to be constructed firstly in the supporting construction process to play a role of temporarily supporting the assembled support, but the vertical construction precision is difficult to guarantee.

Disclosure of Invention

In order to overcome the defects in the prior art, the invention aims to provide a foundation pit inner support structure capable of being vertically positioned and adjusted and a construction method, which can ensure the stability and safety of a foundation pit and can realize accurate construction.

In order to achieve the purpose, the technical scheme of the invention is a foundation pit inner support structure capable of being vertically positioned and adjusted, which comprises an enclosure structure, a support member and a vertical adjusting and positioning device for supporting and adjusting the vertical position of the support member; 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 support members 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, vertical adjusting and positioning devices are fixed on two opposite side walls of the enclosure structure, and two ends of the supporting member are respectively supported on the vertical adjusting and positioning devices on two sides and connected with the embedded parts on the two sides.

Further, the vertical adjusting and positioning device comprises a positioning I-shaped steel for positioning the supporting member and an adjusting mechanism for adjusting the vertical position of the supporting member; one end of the adjusting mechanism is fixed on the side wall of the enclosure structure, and the other end of the adjusting mechanism is connected with the positioning I-shaped steel; the supporting member is supported on the positioning I-shaped steel.

Furthermore, the adjusting mechanism comprises a first length adjustable rod, a second length adjustable rod, a third length adjustable rod and a fourth length adjustable rod; the first length adjustable rod is horizontally arranged, and the positioning I-shaped steel is fixed on the first length adjustable rod; the first length adjustable rod, the second length adjustable rod and the third length adjustable rod are connected end to form a triangular shape; the joint of the second length-adjustable rod and the third length-adjustable rod is connected with the first fixing piece on the side wall of the enclosure structure; one end of the fourth length adjustable rod is connected with the joint of the first length adjustable rod and the third length adjustable rod, and the other end of the fourth length adjustable rod is connected with the second fixing piece on the side wall of the enclosure structure.

Furthermore, the first fixing piece is positioned below the second fixing piece, and the first fixing piece and the second fixing piece have the same structure and comprise expansion bolts, fixing steel plates and lug plates; the fixed steel plate is fixed on the side wall of the enclosure structure through expansion bolts, and the ear plate is fixed on the fixed steel plate; the second length adjustable rod and the third length adjustable rod are connected with the ear plate of the first fixing piece, and the fourth length adjustable rod is connected with the ear plate of the second fixing piece.

Furthermore, a concave part for placing the supporting member is arranged on an upper flange plate of the positioning I-shaped steel, and the concave part is matched with the supporting member.

In one embodiment, the support member is formed by splicing a plurality of prefabricated support sections, and a removal gasket is arranged between at least two adjacent prefabricated support sections.

As another embodiment, the supporting member is formed by splicing a plurality of prefabricated supporting segments, one end of the supporting member is connected with a corresponding embedded part through a telescopic structure, a jack is supported between one end of the supporting member, which is connected with the telescopic structure, and the corresponding embedded part, 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 supporting member 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.

The invention also provides a construction method of the foundation pit inner support structure capable of being vertically positioned and adjusted, which comprises the following steps:

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

s2, splicing the prefabricated support sections section by section through a screw and a nut, and simultaneously installing a disassembly gasket between at least two adjacent prefabricated support sections to assemble a support member; the two ends of the supporting member are connected with the embedded parts through screws;

s3, overexcavating the foundation pit, and then installing a vertical adjusting and positioning device at the specified position on the side wall of the enclosure structure;

s4, hoisting the assembled supporting member, and placing the supporting member on a vertical adjusting and positioning device to enable embedded parts at two ends of the supporting member to be placed at the position of a crown beam or a waist beam to be poured;

s5, pouring the crown beam or the waist beam to embed the embedded part therein;

s6, after the construction is finished, firstly, unscrewing the screw rods on the two prefabricated support sections with the disassembly gaskets arranged in the middle, and disassembling the disassembly gaskets;

s7, unscrewing the screw section by section and recovering the prefabricated support sections.

The invention also provides a construction method of the other foundation pit inner support structure capable of being vertically positioned and adjusted, 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 screws and nuts to form a support member; connecting the first expansion joint with a prefabricated support section at one end of the support member 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, overexcavating the foundation pit, and then installing a vertical adjusting and positioning device at the specified position on the side wall of the enclosure structure;

s6, hoisting the assembled support member, placing the support member on a vertical adjusting and positioning device, 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 support member with an embedded screw extending out of an 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) according to the vertical supporting position, the vertical adjusting and positioning device is fixed on the side wall of the building enclosure, so that the vertical position of the supporting member can be accurately positioned according to different overexcavation depths and supporting vertical elevations, the construction error can be adjusted at any time, the vertical accurate construction is realized, and meanwhile, temporary support is provided for the supporting member in the construction process;

(2) rigid connection is adopted between the prefabricated support sections and the crown beam or the waist beam, so that the integrity and the safety of the foundation pit are ensured;

(3) the prefabricated support sections and the embedded parts are connected by the screws, so that the prefabricated support sections are convenient to mount and dismount, and the prefabricated support sections can be recycled.

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 inner supporting structure of a foundation pit, which is capable of vertical positioning adjustment according to an embodiment of the present invention;

fig. 2 is a plan view of another vertically adjustable foundation pit support structure according to an embodiment of the present invention;

FIG. 3 is a longitudinal cross-sectional view of a prefabricated support segment provided in accordance with an embodiment of the present invention;

FIG. 4 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. 5 is a cross-sectional view of a prefabricated support section with a square steel tube according to an embodiment of the present invention;

FIG. 6 is a longitudinal cross-sectional view (without a release liner) of a connecting node structure of prefabricated support segments provided in accordance with an embodiment of the present invention;

FIG. 7 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 (with removable shims);

FIG. 8 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. 9 is a schematic view of an inner ring plate when the steel pipe provided by the embodiment of the present invention is circular;

FIG. 10 is a schematic view of an outer ring plate when a steel pipe according to an embodiment of the present invention is circular;

FIG. 11 is a schematic view of a stiffener according to an embodiment of the present invention;

FIG. 12 is a schematic view of a release liner provided in accordance with an embodiment of the present invention;

FIG. 13 is a schematic view of a prefabricated support segment connected to an embedded part in a crown beam through a telescopic structure according to an embodiment of the present invention;

FIG. 14 is a schematic view of a prefabricated support section directly connected with an embedded part in a crown beam according to an embodiment of the invention;

FIG. 15 is a schematic view of a prefabricated support section positioned on an I-shaped steel when a steel pipe provided by an embodiment of the invention is round;

FIG. 16 is a schematic view of a prefabricated support section positioned on an I-shaped steel when a steel pipe provided by an embodiment of the invention is square;

FIG. 17 is a side view of a first expansion joint and a second expansion joint provided by an embodiment of the present invention;

FIG. 18 is a schematic view of a solid steel plate provided in an embodiment of the present invention;

FIG. 19 is a schematic view of a U-hole steel plate according to an embodiment of the present invention;

FIG. 20 is a schematic view of an embedment provided by an embodiment of the present invention;

FIG. 21 is a schematic view of a first fastener and a second fastener provided in accordance with an embodiment of the present invention;

FIG. 22 is a side view of a first fastener and a second fastener 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 vertical adjusting and positioning device; 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. disassembling the gasket; 30. positioning the I-shaped steel; 31. a first length adjustable rod; 32. a second length adjustable rod; 33. a third length adjustable rod; 34. a fourth length adjustable rod; 35. an ear plate; 36. an expansion bolt; 37. fixing a steel plate; 38. a stiffening plate; 39. pre-burying a steel plate; 40. 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. 1-2, the present embodiment provides a foundation pit inner supporting structure capable of being vertically positioned and adjusted, which includes a building enclosure 1, a supporting member and a vertical adjusting and positioning device 7 for supporting and adjusting the vertical position of the supporting member; 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 support members 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, vertical adjusting and positioning devices 7 are fixed on two opposite side walls of the building enclosure 1, and two ends of the supporting member are respectively supported on the vertical adjusting and positioning devices 7 on two sides and connected with the embedded parts 4 on two sides. According to the embodiment, the vertical adjusting and positioning device 7 is fixed on the side wall of the building enclosure 1 according to the supporting vertical position, the vertical position of the supporting member can be accurately positioned according to different over-excavation depths and supporting vertical elevations, the construction error can be adjusted at any time, vertical accurate construction is realized, and meanwhile temporary support is provided for the supporting member. 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.

Further, the vertical adjusting and positioning device 7 comprises a positioning i-shaped steel 30 for positioning the supporting member and an adjusting mechanism for adjusting the vertical position of the supporting member; one end of the adjusting mechanism is fixed on the side wall of the envelope structure 1, and the other end of the adjusting mechanism is connected with the positioning I-shaped steel 30; the support member is supported on the positioning i-shaped steel 30.

Further, the adjusting mechanism includes a first length-adjustable rod 31, a second length-adjustable rod 32, a third length-adjustable rod 33, and a fourth length-adjustable rod 34; the first length adjustable rod 31 is horizontally arranged, and the positioning i-shaped steel 30 is fixed on the first length adjustable rod 31; the first length adjustable rod 31, the second length adjustable rod 32 and the third length adjustable rod 33 are connected end to form a triangular shape; the joint of the second length adjustable rod 32 and the third length adjustable rod 33 is connected with the first fixing piece on the side wall of the building envelope 1; one end of the fourth length adjustable rod 34 is connected to the connection point of the first length adjustable rod 31 and the third length adjustable rod 33, and the other end is connected to the second fixing member on the sidewall of the enclosure 1. As shown in fig. 13-14, in the present embodiment, by adjusting the lengths of the second length adjustable rod 32, the third length adjustable rod 33 and the fourth length adjustable rod 34, it is ensured that the first length adjustable rod 31 keeps horizontal and reaches a specified vertical elevation, and accurate positioning of the vertical position is achieved; the sizes of the first length adjustable rod 31, the second length adjustable rod 32, the third length adjustable rod 33 and the fourth length adjustable rod 34, the distance between the positioning devices 7 and the size of the positioning i-shaped steel 30 are determined according to the stress calculation.

Furthermore, the first fixing piece is located below the second fixing piece, and the first fixing piece and the second fixing piece have the same structure and each include an expansion bolt 36, a fixing steel plate 37 and an ear plate 35; the fixed steel plate 37 is fixed on the side wall of the enclosure structure 1 through an expansion bolt 36, and the ear plate 35 is fixed on the fixed steel plate 37; the second length adjustable rod 32 and the third length adjustable rod 33 are both connected to the ear plate 35 of the first fixing member, and the fourth length adjustable rod 34 is connected to the ear plate 35 of the second fixing member. As shown in fig. 13-14, the second length adjustable rod 32 and the third length adjustable rod 33 of the present embodiment are hinged to the ear plate 35 of the first fixing member, and the fourth length adjustable rod 34 is hinged to the ear plate 35 of the second fixing member, so that the vertical adjusting and positioning device 7 can be conveniently detached, and recycling can be achieved.

Further, a concave portion for placing the supporting member is arranged on the upper flange plate of the positioning i-shaped steel 30, and the concave portion is matched with the supporting member. In the embodiment, the lower flange plate of the positioning i-shaped steel 30 is fixed to one end of the first length adjustable rod 31, which is far away from the third length adjustable rod 33 and the fourth length adjustable rod 34, through the ear plate 35; when the steel pipe 11 is round, a concave part matched with the steel pipe 11 is arranged on the upper flange plate of the positioning I-shaped steel 30 so as to position the supporting member, as shown in FIG. 15, and the position of the concave part is matched with the distance and the size of the supporting member, and prefabrication is completed in a factory; when the steel pipe 11 is square, the positioning support can be directly placed on the upper flange plate of the positioning i-shaped steel 30, as shown in fig. 16.

As an embodiment, the supporting member is formed by splicing a plurality of prefabricated supporting sections 3, and a removal gasket 29 is arranged between at least two adjacent prefabricated supporting sections 3, as shown in fig. 2, and the connection mode shown in fig. 14 is adopted for the connection node of the two ends of the supporting member and the crown beam 2 or the wale. The support member of the embodiment is provided with at least one detachable gasket 29, and the detachable gasket 29 is placed between two prefabricated support sections 3, so that the detachable gasket 29 can be detached firstly during detachment, the axial force between the prefabricated support sections 3 is eliminated, and the rest prefabricated support sections 3 can be detached easily, thereby effectively solving the problem of difficulty in detaching the assembled support with the length of several meters and improving the detaching efficiency of the assembled support; the disassembling gasket 29 can be a solid steel ring with the thickness of 3-10cm, or a solid steel ring formed by splicing multiple sections, such as two semicircular steel rings or multiple fan-shaped steel rings, and the multiple sections of steel rings are not connected; the surface of the disassembly gasket 29 needs to be smooth, a layer of lubricant can be coated on the two side surfaces of the disassembly gasket 29 before installation, the difficulty in disassembling the disassembly gasket 29 is much smaller, once the disassembly gasket 29 is disassembled, the axial force among the prefabricated support sections 3 disappears, and the rest prefabricated support sections 3 can be easily disassembled.

As another embodiment, the supporting member is formed by splicing a plurality of prefabricated supporting sections 3, one end of the supporting member is connected with the corresponding embedded part 4 through a telescopic structure, a jack 25 is supported between one end of the supporting member, which is connected with the telescopic structure, and the corresponding embedded part 4, the jack 25 is electrically connected with a control system 27, as shown in fig. 1, a connection mode of one end of the supporting member and a crown beam 2 or a wale is adopted as a connection node of fig. 13, and a connection mode of the other end of the supporting member and the crown beam 2 or the wale is adopted as a connection node of fig. 14; the length of the end joint can be adjusted through the telescopic structure, so that the construction error can be adjusted; meanwhile, the jack 25 is arranged, the jack 25 is an intelligent jack 25, the jack 25 has enough jacking force, can sense self stress and transmit the self stress to the control system 27 through the lead 26, the control system 27 makes corresponding response according to the stress to adjust the jacking force and the elongation of the jack, and an intelligent stress compensation device is formed, can construct prestress according to needs, meets the requirements of repeated loading for prestress loss and support relaxation, can timely compensate the stress when the stress is relaxed in the use process of the assembled support, can timely warn when the stress is too large, and can prevent local instability of the foundation pit from causing the damage of the whole foundation pit; the jack 25 should not be oversized to avoid interfering with the connection of the telescoping structures.

As shown in fig. 13 and 17 to 19, the telescopic structure includes a first telescopic joint 5 and a second telescopic joint 6, where the first telescopic joint 5 and the second telescopic joint 6 are respectively connected to the supporting member and the embedded part 4 and have the same structure, and each of the first telescopic joint 5 and the second telescopic joint includes a solid steel plate 20, a U-hole steel plate 21, a U-shaped steel plate 22, and a stiffening plate 38; 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 38, 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 the embodiment is provided with multiple rows of long round holes 23, the long round holes 23 are arranged along the supporting direction, the long round holes 23 in the first expansion joint 5 are connected with the long round holes 23 in the second expansion joint 6 through bolts 24, the end parts of the supporting members and the crown beam 2 or waist beam joints adopt the variable-length round hole 23 steel box slot joints, the rigid connection and equal-strength connection requirements of the side joints can be met, the engineering safety and the detachability of the end part joints are ensured, the prefabricated members can be conveniently recycled, meanwhile, the lengths of the joints can be changed by adjusting the relative positions of the long round holes 23 according to needs, and therefore construction errors are 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.

The size of the U-shaped steel plate 22 of the first expansion joint 5 is smaller than that 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 just 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 38 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 38 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 the cast-in-place concrete support are ensured. As shown in fig. 13, the stiffener plate 38 of the present embodiment has the same structure as the stiffener 9 and is slightly larger than the stiffener 9.

In the above two embodiments of the supporting member, the prefabricated supporting sections 3 may be supported by concrete-filled hollow steel tubes, as shown in fig. 4 and 5, or by pure steel supports and pure concrete supports, or 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; if the prefabricated support sections 3 can be designed into standard modules with the specifications of 4m, 5m, 6m and the like and end section modules with the length of 2m, the prefabricated support sections 3 with the completely same, incompletely same or completely different length specifications are selected to be assembled according to the actual foundation pit requirements, the requirement of foundation pit support with different widths and lengths is met, and the universal applicability is achieved.

Further, 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; the inner ring plate 10 and the outer ring plate 8 which are positioned at the same end of the steel pipe 11 are connected 9 through a stiffening rib, and the stiffening rib 9 is welded with the steel pipe 11; a plurality of screw holes 19 are formed in the inner ring plate 10 and the outer ring plate 8 at intervals along the circumferential direction, and the screw holes 19 in the outer ring plate 8 correspond to the screw holes 19 in the inner ring plate 10 one by one; 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. 6 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 rigidity of the joint, 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 respectively welded to the stiffening ribs 9, the steel pipe 11 and the sealing plate 14, and three sides of the stiffening ribs 9 are respectively welded to the outer ring plate 8, the inner ring plate 10 and the steel pipe 11 to ensure the rigidity of the joint at the joint; the boot beam nodes at the end parts of the prefabricated support sections 3 are connected through the plurality of screw rods 17, so that the rigid connection of the middle nodes is ensured, the equal strength of the nodes and the members is realized, the support members are ensured to achieve the strength and rigidity similar to or even higher than those of cast-in-place concrete support, the safety and stability of foundation pit engineering are ensured, the installation and the disassembly are convenient, and the factory production and the large-area popularization and application are facilitated; 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. In the case of a support member with a removal gasket 29 between prefabricated support segments 3, a plurality of screw holes 19 are formed in the removal gasket 29, and the screw holes 19 in the removal gasket 29 correspond to the screw holes 19 in the outer ring plate 8 and the screw holes 19 in the inner ring plate 10 one by one; the screw 17 passes through the corresponding screw hole 19 on the disassembling gasket 29; as shown in fig. 7 and 12, the size of the removing shim 29 in this embodiment may be the same as that of the inner ring plate 10, a plurality of screw holes 19 are uniformly arranged along the circumferential direction on the outer edge, and the screw holes 19 on the removing shim 29 correspond to the screw holes 19 on the inner ring plate 10 and the outer ring plate 8 of the prefabricated support segment 3 one by one.

On the basis of the prefabricated support segment 3 with the steel structure, filling concrete 16 is poured in the steel pipe 11, and a hollow part which penetrates through the filling concrete 16 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 two materials of the steel pipe 11 and the concrete can be fully exerted, the cost performance is high, the weight and the strength are light, the recycling, the transportation and the installation are convenient, and compared with a pure steel support, the hollow steel pipe 11 has obvious economic benefit, and compared with a concrete support, the rigidity is higher, 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, meanwhile, the bearing capacity of the filling concrete can be obviously improved under the hoop effect of the steel pipe 11, the bearing capacity (strength) of the concrete support of the hollow steel pipe 11 is high, the deformation resistance (rigidity) is high, the same as or even higher strength and rigidity of the conventional concrete support can be achieved, and the engineering safety; and the hollow parts of the prefabricated support segments 3 of the support member 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. 4, 9 and 10, 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. 5, 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, which 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. 3-7, 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, a plurality of the stiffening ribs 9 are arranged between the inner ring plate 10 and the outer ring plate 8 at intervals along the circumferential direction, and the stiffening ribs 9 and the screw rods 17 are arranged at intervals. As shown in fig. 8, the stiffening ribs 9 are arranged between the pair of 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, and the plurality of stiffening ribs 9 and the plurality of screws 17 are arranged at intervals, so that the strength and rigidity of the connecting node 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, 7 and 11, in the present embodiment, the two corners of the side edge connecting the stiffening rib 9 and the steel pipe 11 are chamfered to form a chamfered structure, so as to effectively reduce stress concentration during the welding process; 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.

Further, embedded parts 4 are embedded in the crown beam 2 and the waist beam, and each embedded part 4 comprises two embedded steel plates 39 and a plurality of embedded screws 40; one end of each of the plurality of embedded screws 40 sequentially penetrates through the two embedded steel plates 39 and is welded with the two embedded steel plates 39, and the other end of each of the plurality of embedded screws extends out of the crown beam 2 or the wale and 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 of the supporting member and is fixed by a screw cap 18. As shown in fig. 13-14 and 20, the two embedded steel plates 39 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 39 are provided with a plurality of screw holes 19, and are in one-to-one correspondence with the inner ring plate 10 and the plurality of screw holes 19 on the outer ring plate 8, one ends of a plurality of embedded screws 40 correspondingly penetrate through the corresponding screw holes 19 on the two embedded steel plates 39 and are welded with the embedded steel plates 39, and the other ends of the plurality of embedded screws correspondingly penetrate through the plurality of screw holes 19 on the inner ring plate 10 and the plurality of screw holes 19 on the outer ring plate 8 and 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 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

As shown in fig. 2, the present embodiment provides a construction method of an inner supporting structure of a foundation pit capable of vertical positioning adjustment, wherein a disassembly gasket 29 is provided between prefabricated supporting sections 3 of a supporting member, the method includes the following steps:

s1, manufacturing the prefabricated support sections 3 and the embedded parts 4 in a factory according to a design drawing, and transporting to a construction site;

s2, splicing the prefabricated support sections 3 section by section through the screw rods 17 and the nuts, and meanwhile installing the disassembling gasket 29 between at least two adjacent prefabricated support sections 3 to assemble the support member; the two ends of the supporting component are connected with the embedded part 4 through screw rods 17;

s3, overexcavating the foundation pit, and then installing a vertical adjusting and positioning device 7 at the specified position on the side wall of the enclosure structure 1;

s4, placing the hoisted and assembled supporting component on a vertical adjusting and positioning device 7, and placing the embedded parts 4 at two ends of the supporting component at the positions of the crown beam 2 or the waist beam to be poured;

s5, pouring the crown beam 2 or the waist beam to embed the embedded part 4 therein;

s6, after the construction is finished, firstly, unscrewing the screw rods 17 on the two prefabricated support sections 3 with the disassembly gaskets 29 arranged in the middle, and disassembling the disassembly gaskets 29;

s7, unscrewing the screw 17 segment by segment and recovering the prefabricated support segments 3.

In this embodiment, the embedded parts 4 at the two ends of the supporting member are firstly placed at the positions of the crown beam 2 or the waist beam to be cast, then the crown beam 2 or the waist beam is cast, and meanwhile, the embedded parts 4 at the two ends of the supporting member are cast in the position, so that the strength of the two ends of the supporting member and the nodes of the crown beam 2 or the waist beam is improved, and the safety and stability of the foundation pit engineering are ensured.

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, 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 two prefabricated support sections 3 with the disassembly gasket 29 arranged in the middle are assembled, firstly, a layer of lubricant is coated on two side surfaces of the disassembly gasket 29, then the disassembly gasket 29 is arranged between the two prefabricated support sections 3, the screw 17 sequentially penetrates through the outer ring plate 8 and the inner ring plate 10 at the end part of one prefabricated support section 3, the disassembly gasket 29, the inner ring plate 10 at the end part of the other prefabricated support section 3 and the screw hole 19 on the outer ring plate 8 and is fixed through the screw cap 18, when the disassembly is carried out, the screw 17 and the screw cap 18 are firstly disassembled, then the disassembly gasket 29 is disassembled, the axial force between the prefabricated components is eliminated, and then the prefabricated support sections 3 are disassembled section by section. 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.

EXAMPLE III

As shown in fig. 1, the present embodiment provides the above construction method of a support structure in a foundation pit with a retractable structure and capable of vertical positioning adjustment, wherein one end of the support member is directly connected to an embedded part 4 in a crown beam 2 or a wale, and the other end is connected to the embedded part 4 in the crown beam 2 or the wale through the retractable structure, and the method 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 into a support member section by section through the screw rods 17 and the screw caps 18; and the first expansion joint 5 is connected with the prefabricated support section 3 at one end of the support member 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 40 extending out of the embedded part 4 on one side through the screw cap 18;

s5, overexcavating the foundation pit, and then installing a vertical adjusting and positioning device 7 at the specified position on the side wall of the enclosure structure 1;

s6, hoisting the assembled supporting member, placing the assembled supporting member on a vertical adjusting and positioning device 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 supporting section 3 at the other end of the supporting member with the embedded screw 40 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 embedded screw 40 and nut 18 with built-in fitting 4 to be connected, prefabricated support segment 3 and the built-in fitting 4 that the assembled supported the other end pass through embedded screw rod 40 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 earlier with the bolt 24 of connecting first expansion joint 5 with second expansion joint 6, 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.

The specific method of manufacturing the prefabricated support section 3 in the factory in step S1 of this embodiment may adopt the manufacturing method of the second embodiment.

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 embedded screws 40 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 fabricated supporting members in the second embodiment and the third embodiment can be rigidly connected with the crown beam 2 or the wale, so that in the ultra-deep foundation pit, the fabricated supporting members can replace a plurality of traditional concrete supports, and the assembly rate is improved.

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 a but vertical location adjusts's foundation ditch inner support structure which characterized in that: the building enclosure comprises an enclosure structure, a supporting member and a vertical adjusting and positioning device for supporting and adjusting the vertical position of the supporting member; 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 support members 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, vertical adjusting and positioning devices are fixed on two opposite side walls of the enclosure structure, and two ends of the supporting member are respectively supported on the vertical adjusting and positioning devices on two sides and connected with the embedded parts on the two sides.

2. A vertically positionally adjustable foundation pit internal support structure as claimed in claim 1, wherein: the vertical adjusting and positioning device comprises a positioning I-shaped steel for positioning the supporting member and an adjusting mechanism for adjusting the vertical position of the supporting member; one end of the adjusting mechanism is fixed on the side wall of the enclosure structure, and the other end of the adjusting mechanism is connected with the positioning I-shaped steel; the supporting member is supported on the positioning I-shaped steel.

3. A vertically positionally adjustable foundation pit internal support structure as claimed in claim 2, wherein: the adjusting mechanism comprises a first length adjustable rod, a second length adjustable rod, a third length adjustable rod and a fourth length adjustable rod; the first length adjustable rod is horizontally arranged, and the positioning I-shaped steel is fixed on the first length adjustable rod; the first length adjustable rod, the second length adjustable rod and the third length adjustable rod are connected end to form a triangular shape; the joint of the second length-adjustable rod and the third length-adjustable rod is connected with the first fixing piece on the side wall of the enclosure structure; one end of the fourth length adjustable rod is connected with the joint of the first length adjustable rod and the third length adjustable rod, and the other end of the fourth length adjustable rod is connected with the second fixing piece on the side wall of the enclosure structure.

4. A vertically positionally adjustable foundation pit internal support structure as claimed in claim 3, wherein: the first fixing piece is positioned below the second fixing piece, the first fixing piece and the second fixing piece are identical in structure and respectively comprise an expansion bolt, a fixing steel plate and an ear plate; the fixed steel plate is fixed on the side wall of the enclosure structure through expansion bolts, and the ear plate is fixed on the fixed steel plate; the second length adjustable rod and the third length adjustable rod are connected with the ear plate of the first fixing piece, and the fourth length adjustable rod is connected with the ear plate of the second fixing piece.

5. A vertically positionally adjustable foundation pit internal support structure as claimed in claim 2, wherein: and the upper flange plate of the positioning I-shaped steel is provided with a concave part for placing the supporting member, and the concave part is matched with the supporting member.

6. A vertically positionally adjustable foundation pit internal support structure as claimed in any one of claims 1 to 5, wherein: the supporting member is formed by splicing a plurality of prefabricated supporting sections, and a disassembling gasket is arranged between at least two adjacent prefabricated supporting sections.

7. A vertically positionally adjustable foundation pit internal support structure as claimed in any one of claims 1 to 5, wherein: the supporting member is formed by splicing a plurality of prefabricated supporting sections, one end of the supporting member is connected with the corresponding embedded part through a telescopic structure, a jack is supported between one end of the supporting member, which is connected with the telescopic structure, and the corresponding embedded part, and the jack is electrically connected with the control system.

8. A vertically positionally adjustable foundation pit internal support structure as claimed in claim 7, 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 supporting member 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.

9. A method of constructing a vertically adjustably positionable support structure within an excavation as claimed in claim 6, comprising the steps of:

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

s2, splicing the prefabricated support sections section by section through a screw and a nut, and simultaneously installing a disassembly gasket between at least two adjacent prefabricated support sections to assemble a support member; the two ends of the supporting member are connected with the embedded parts through screws;

s3, overexcavating the foundation pit, and then installing a vertical adjusting and positioning device at the specified position on the side wall of the enclosure structure;

s4, hoisting the assembled supporting member, and placing the supporting member on a vertical adjusting and positioning device to enable embedded parts at two ends of the supporting member to be placed at the position of a crown beam or a waist beam to be poured;

s5, pouring the crown beam or the waist beam to embed the embedded part therein;

s6, after the construction is finished, firstly, unscrewing the screw rods on the two prefabricated support sections with the disassembly gaskets arranged in the middle, and disassembling the disassembly gaskets;

s7, unscrewing the screw section by section and recovering the prefabricated support sections.

10. A method of constructing a vertically adjustably positionable support structure in a foundation pit according to claim 7 or claim 8, including 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 screws and nuts to form a support member; connecting the first expansion joint with a prefabricated support section at one end of the support member 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, overexcavating the foundation pit, and then installing a vertical adjusting and positioning device at the specified position on the side wall of the enclosure structure;

s6, hoisting the assembled support member, placing the support member on a vertical adjusting and positioning device, 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 support member with an embedded screw extending out of an 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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