CN218713083U - Adjustable foundation pit excavation supporting structure - Google Patents

Abstract

The utility model discloses an adjustable foundation pit excavation supporting structure, which comprises a first guardrail (1), a second guardrail (2), a support rod (3), a stabilizing component (4) and an adjusting component (5); the first supporting guardrail (1) and the second supporting guardrail (2) are of U-shaped structures with one open ends, and the open end of the first supporting guardrail (1) is connected with the open end of the second supporting guardrail (2) in an adjustable manner through an adjusting assembly (5); the upper ends of the support rods (3) are respectively and fixedly connected with the two sides of the sealing end of the first support guardrail (1) and the second support guardrail (2), and the upper ends of the stabilizing components (4) are respectively connected with the lower ends of the support rods (3) in an adjustable mode. The utility model discloses can adjust the length and the height of first guardrail and second guardrail.

Description

Adjustable foundation pit excavation supporting structure

Technical Field

The utility model relates to a excavation supporting construction especially relates to a excavation supporting construction with adjustable.

Background

The foundation pit supporting structure system generally comprises two parts, namely a soil retaining structure and a precipitation and water stop system, and the pile and wall type supporting structure usually adopts steel sheet piles, reinforced concrete sheet piles, column type cast-in-place piles, underground continuous walls and the like. At present, a foundation pit excavation supporting structure is also commonly used for auxiliary construction in tunnel shield construction.

In order to ensure the bearing capacity and the supporting effect of the foundation pit supporting structure, the foundation pit supporting structure in the prior art is usually a fixed structure, the foundation pit supporting structure is required to be customized according to the size of a foundation pit, and the foundation pit supporting structure is formed by welding and fixing steel materials. However, the construction environment is complex, the excavation depth and the length of the foundation pit may change, and the fixed structure of the foundation pit supporting structure has no adjusting capability, so that the universality and the use flexibility of the foundation pit supporting structure are poor. For different foundation pit construction projects or different construction stages of the foundation pit, the foundation pit supporting structure with matched size needs to be configured correspondingly, so that the construction cost is high, and the use is inconvenient. Therefore, it is desirable to provide an adjustable excavation supporting structure.

Disclosure of Invention

An object of the utility model is to provide a excavation supporting construction with adjustable can adjust the length and the height of first guardrail and second guardrail.

The utility model discloses a realize like this:

an adjustable foundation pit excavation supporting structure comprises a first support guardrail, a second support guardrail, a support rod, a stabilizing assembly and an adjusting assembly; the first support guardrail and the second support guardrail are of U-shaped structures with one ends open, and the open ends of the first support guardrail and the second support guardrail are connected in an adjustable mode through adjusting components; the upper ends of the plurality of supporting rods are respectively and fixedly connected with the two sides of the sealing end of the first supporting guardrail and the two sides of the sealing end of the second supporting guardrail, and the upper ends of the plurality of stabilizing assemblies are respectively connected with the lower ends of the plurality of supporting rods in an adjustable mode.

Each group of stabilizing assemblies comprises a threaded column, a base, a rotating mechanism and a first positioning mechanism; the base is in a conical structure with a narrow upper part and a wide lower part and is coaxially connected with the lower end of the threaded column; the support rod is a hollow tubular structure, the rotating mechanism is arranged at the bottom of the support rod, and the upper end of the threaded column is in threaded connection with the rotating mechanism, so that the upper end of the threaded column can be coaxially inserted into the support rod in a rotating and adjusting manner; the first positioning mechanism is embedded in the pipe wall of the supporting rod and movably inserted with the rotating mechanism.

The rotating mechanism comprises a rotating ring, a connecting ring and a guide wheel; a rotating ring groove is axially formed at the bottom of the supporting rod, the rotating ring is rotatably embedded in the rotating ring groove, and the connecting ring is coaxially connected with the rotating ring and the guide wheel, so that the guide wheel is positioned below the bottom of the supporting rod; the middle parts of the rotating ring, the connecting ring and the guide wheel are respectively provided with an internal thread matched with the threaded column, so that the threaded column is screwed in and penetrates through the rotating ring, the connecting ring and the guide wheel; the first positioning mechanism is movably inserted on the guide wheel.

The diameter of the rotating ring is larger than that of the connecting ring and smaller than that of the guide wheel, so that the rotating mechanism is in an I-shaped circular structure.

The first positioning mechanism comprises a fixed spring, a push rod, a convex block and a bolt; the pipe wall of the supporting rod is internally provided with a mounting groove, the upper end of the fixed spring is fixedly connected with the upper end of the mounting groove, and the lower end of the fixed spring is fixedly connected with the upper end of the push rod, so that the connecting push rod can be elastically embedded in the mounting groove through the fixed spring; a sliding groove communicated with the mounting groove is formed in the pipe wall of the supporting rod, one end of the convex block is arranged on the push rod, and the other end of the convex block penetrates through the sliding groove and extends to the outside of the supporting rod; the upper end of the bolt is connected to the bottom of the connecting push rod, a plurality of first positioning holes are formed in the guide wheel at intervals, and the lower end of the bolt can be movably inserted into one of the first positioning holes.

The adjusting component comprises a toothed bar, a rotating mechanism, a gear and a second positioning mechanism; one end of the toothed bar is fixedly connected to the end part of the opening end of the first guardrail, and an adjusting slot is formed in the opening end of the second guardrail, so that the other end of the toothed bar can be inserted into the adjusting slot; the top of the open end of the second support guardrail is provided with a meshing groove communicated with the adjusting slot, and the gear is rotatably arranged in the meshing groove through a rotating mechanism so as to be meshed and connected with the toothed bar; the second positioning mechanism is arranged on the side part of the opening end of the second support guardrail and is movably inserted with the toothed bar.

The rotating mechanism comprises a mounting block, a rotating shaft and a rotating wheel; the pair of mounting blocks are fixedly mounted on the top surface of the opening end of the second support guardrail respectively and are positioned on two sides of the meshing groove, two ends of the rotating shaft can rotatably penetrate through the pair of mounting blocks, and the gear is coaxially mounted on the rotating shaft and positioned between the pair of mounting blocks; the rotating wheel is coaxially connected with one end of the rotating shaft.

The second positioning mechanism comprises a mounting piece, a positioning rod, a dragging block and a telescopic spring; the mounting piece is fixedly arranged at the end part of the opening end of the second guardrail, a plurality of second positioning holes are formed in the toothed bar at intervals, a third positioning hole is formed in the mounting piece and can be aligned with one of the second positioning holes, and one end of the positioning rod can penetrate through the mounting piece through the third positioning hole and is movably inserted into the toothed bar through the second positioning hole; the dragging block is arranged at the other end of the positioning rod, the diameter of the dragging block is larger than the aperture of the third positioning hole, and the telescopic spring is sleeved on the positioning rod and connected between the mounting piece and the dragging block.

Compared with the prior art, the utility model, following beneficial effect has:

1. the utility model is provided with the stabilizing component and the supporting rod, and the extension length of the threaded column in the supporting rod can be adjusted through the thread rotation of the guide wheel, so that the lengths of the supporting rod and the stabilizing component are adjusted, and the height supporting requirements of the first guardrail and the second guardrail are met to adapt to foundation pit supporting at different depths; reliable locking of subassembly and bracing piece is stabilized in the realization of pegging graft through screw thread interlock and location simultaneously to guarantee the vertical supporting ability of first guardrail and second guardrail.

2. The utility model discloses owing to be equipped with first guardrail, second guardrail and adjusting part, can realize the concatenation length adjustment of first guardrail and second guardrail through adjusting part meshing transmission to adapt to the excavation supporting of different length, peg graft the flexible locking that realizes first guardrail and second guardrail through the location simultaneously, with the horizontal supporting ability of guaranteeing first guardrail and second guardrail.

3. The utility model discloses simple structure adjusts convenience, swift, uses in a flexible way, and is with low costs, has good universality and practicality, applicable in the construction of strutting of different forms, different construction stage's foundation ditch.

Drawings

Fig. 1 is a perspective view of the adjustable supporting structure for excavation of foundation pit of the utility model;

FIG. 2 is a perspective view of a stabilizing assembly in the adjustable excavation supporting structure of the present invention;

FIG. 3 is an enlarged schematic view at A in FIG. 2;

fig. 4 is a perspective view of an adjusting assembly in the adjustable foundation pit excavation supporting structure of the utility model;

fig. 5 is an enlarged schematic view at B in fig. 4.

In the figure, 1, a first support fence; 2. a second guardrail; 3. a support bar; 31. rotating the ring groove; 32. mounting grooves; 33. a sliding groove; 4. a stabilizing assembly; 41. a threaded post; 42. a base; 43. a rotating ring; 44. a guide wheel; 45. fixing the spring; 46. a push rod; 47. a bump; 48. a bolt; 49. a first positioning hole; 410. a connecting ring; 5. an adjustment assembly; 51. a rack bar; 52. mounting blocks; 53. a rotating shaft; 54. a gear; 55. a rotating wheel; 56. mounting a sheet; 57. positioning a rod; 58. dragging the block; 59. a tension spring; 510. an engagement groove; 511. a second positioning hole; 512. and a third positioning hole.

Detailed Description

The invention will be further explained with reference to the drawings and the specific embodiments.

Referring to the attached drawing 1, an adjustable foundation pit excavation supporting structure comprises a first supporting guardrail 1, a second supporting guardrail 2, a supporting rod 3, a stabilizing component 4 and an adjusting component 5; the first branch guardrail 1 and the second branch guardrail 2 are of U-shaped structures with one ends opened, and the opening end of the first branch guardrail 1 is connected with the opening end of the second branch guardrail 2 in an adjustable mode through an adjusting assembly 5; the upper ends of the plurality of support rods 3 are respectively and fixedly connected with the two sides of the sealing end of the first guardrail 1 and the second guardrail 2, and the upper ends of the plurality of stabilizing assemblies 4 are respectively and adjustably connected with the lower ends of the plurality of support rods 3.

First guardrail 1 and second guardrail 2 pass through adjusting part 5 concatenation, constitute the annular supporting construction of rectangle, and first guardrail 1 and second guardrail 2 accessible adjusting part 5 adjust concatenation length simultaneously to adapt to the excavation supporting demand of different length. Bracing piece 3 and stabilizing component 4 are used for providing stable support to first guardrail 1 and second guardrail 2, and the length adjustment between accessible bracing piece 3 and stabilizing component 4 adapts to the excavation supporting demand of the different degree of depth simultaneously.

Referring to fig. 1 and 2, each set of the stabilizing assemblies 4 includes a threaded post 41, a base 42, a rotating mechanism and a first positioning mechanism; the base 42 is in a conical structure with a narrow upper part and a wide lower part and is coaxially connected with the lower end of the threaded column 41; the support rod 3 is a hollow tubular structure, the rotating mechanism is arranged at the bottom of the support rod 3, and the upper end of the threaded column 41 is in threaded connection with the rotating mechanism, so that the upper end of the threaded column 41 can be rotatably and adjustably coaxially inserted into the support rod 3; the first positioning mechanism is embedded in the pipe wall of the support rod 3 and movably inserted with the rotating mechanism.

Adjust the length that the screw post 41 inserted in the bracing piece 3 through the screw rotation to adjust the total length of stabilizing component 4 and bracing piece 3, realize the altitude mixture control to first guardrail 1 and second guardrail 2, in order to satisfy the first guardrail 1 and the second guardrail 2 demand of strutting the different degree of depth foundation ditch. The quantity of bracing piece 3 and stabilizing component 4 can support the demand adjustment according to the reality, and every corner of preferred first guardrail 1 and second guardrail 2 respectively sets up a set of bracing piece 3 and stabilizing component 4 to guarantee reliably to support and strut the atress evenly.

Referring to fig. 3, the rotating mechanism includes a rotating ring 43, a connecting ring 410 and a guide wheel 44; a rotating ring groove 31 is axially formed at the bottom of the support rod 3, the rotating ring 43 is rotatably embedded in the rotating ring groove 31, and the connecting ring 410 is coaxially connected with the rotating ring 43 and the guide wheel 44, so that the guide wheel 44 is positioned below the bottom of the support rod 3; the middle parts of the rotating ring 43, the connecting ring 410 and the guide wheel 44 are all provided with internal threads matched with the threaded column 41, so that the threaded column 41 is screwed in the threads and penetrates through the rotating ring 43, the connecting ring 410 and the guide wheel 44; the first positioning mechanism is movably inserted on the guide wheel 44.

The rotating ring 43 can rotate in the rotating ring groove 31, so that the guide wheel 44 can be rotatably mounted at the bottom of the support rod 3, the rotating motion of the guide wheel 44 is converted into the axial linear motion of the threaded column 41 through threads, and the splicing length of the support rod 3 and the threaded column 41 is adjusted, so that the height adjusting requirement between the base 42 and the first and second support guardrails 1 and 2 is met. The locking and fixing between the support rod 3 and the threaded column 41 are realized by the thread engagement between the guide wheel 44 and the threaded column 41.

The diameter of the rotating ring 43 is larger than that of the connecting ring 410 and smaller than that of the guide wheel 44, so that the rotating mechanism is in an I-shaped ring structure.

The rotation ring 34 forms a limit in the rotation ring groove 31 to prevent the guide wheel 44 from falling off, and also to ensure the rotation of the guide wheel 44 relative to the support rod 3 and the threaded post 41.

Referring to fig. 3, the first positioning mechanism includes a fixed spring 45, a push rod 46, a protrusion 47 and a latch 48; the pipe wall of the support rod 3 is internally provided with a mounting groove 32, the upper end of the fixed spring 45 is fixedly connected with the upper end of the mounting groove 32, and the lower end of the fixed spring 45 is fixedly connected with the upper end of the push rod 46, so that the connecting push rod 46 can be elastically embedded in the mounting groove 32 through the fixed spring 45; a sliding groove 33 communicated with the mounting groove 32 is formed on the tube wall of the support rod 3, one end of a convex block 47 is arranged on the push rod 46, and the other end of the convex block 47 penetrates through the sliding groove 33 and extends to the outside of the support rod 3; the upper end of the bolt 48 is connected to the bottom of the connecting rod 46, a plurality of first positioning holes 49 are formed on the guide wheel 44 at intervals, and the lower end of the bolt 48 can be movably inserted into one of the first positioning holes 49.

The push rod 46 and the bolt 48 are driven to synchronously slide and lift along the mounting groove 32 by the rising and falling of the convex block 47, so that the bolt 48 is inserted into the first positioning hole 49 to realize the locking between the support rod 3 and the guide wheel 44, and the relative rotation and lifting are prevented, thereby ensuring the support stability of the support rod 3 and the threaded column 41 to the first support fence 1 and the second support fence 2; meanwhile, the bolt 48 can be disengaged from the first positioning hole 49, so that the relative rotation between the support rod 3 and the guide wheel 44 is realized, and the support rod 3 and the threaded column 41 can be conveniently adjusted by threaded rotation. Through the setting of fixed spring 45, compress and compress tightly bolt 48 downwards when bolt 48 inserts to first locating hole 49, prevent that bolt 48 from deviating from first locating hole 49, fixed spring 45 further compresses when bolt 48 extracts first locating hole 49, is convenient for restore the back to the release of lug 47 and inserts in first locating hole 49 bolt 48.

Referring to fig. 1 and 4, the adjusting assembly 5 includes a rack 51, a rotating mechanism, a gear 54 and a second positioning mechanism; one end of the toothed bar 51 is fixedly connected with the end part of the opening end of the first sub-guardrail 1, and an adjusting slot (not shown in the figure) is formed in the opening end of the second sub-guardrail 2, so that the other end of the toothed bar 51 can be inserted into the adjusting slot; the top of the open end of the second support fence 2 is provided with an engagement groove 510 communicated with the adjusting slot, and the gear 54 is rotatably arranged in the engagement groove 510 through a rotating mechanism, so that the gear 54 is engaged with the rack bar 51; the second positioning mechanism is arranged at the side part of the opening end of the second support fence 2, and the second positioning mechanism is movably inserted with the toothed bar 51.

The gear 54 is driven by the rotating mechanism to rotate, and the gear 54 is meshed with the toothed bar 51 to convert the rotating motion of the gear 54 into the linear motion of the toothed bar 51, so that the second guardrail 2 moves away from and approaches to the first guardrail 1; a set of adjusting component 5 is arranged on two sides of the opening end of the second branch guardrail 2 and the opening end of the first branch guardrail 1, so that the connection reliability and the length adjusting flexibility between the second branch guardrail 2 and the first branch guardrail 1 are guaranteed, and the supporting requirements of foundation pits with different lengths are met.

Referring to fig. 4, the rotating mechanism includes a mounting block 52, a rotating shaft 53 and a rotating wheel 55; the pair of mounting blocks 52 are respectively fixedly mounted on the top surface of the open end of the second support fence 2 and located on both sides of the engagement groove 510, both ends of the rotating shaft 53 rotatably penetrate the pair of mounting blocks 52, and the gear 54 is coaxially mounted on the rotating shaft 53 and located between the pair of mounting blocks 52; the runner 55 is coaxially connected to one end of the rotating shaft 53.

The rotating wheel 55 is manually rotated, so that the rotating wheel 55 drives the rotating shaft 53 to synchronously rotate, and the rotating shaft 53 drives the gear 54 to synchronously rotate, thereby realizing the meshing transmission of the toothed bar 51 and further realizing the motion adjustment of the second guardrail 2 relative to the first guardrail 1.

Referring to fig. 5, the second positioning mechanism includes a mounting plate 56, a positioning rod 57, a dragging block 58 and a telescopic spring 59; the mounting piece 56 is fixedly arranged at the end part of the opening end of the second support guardrail 2, a plurality of second positioning holes 511 are formed at intervals on the toothed bar 51, a third positioning hole 512 is formed on the mounting piece 56, the third positioning hole 512 can be aligned with one of the second positioning holes 511, and one end of the positioning rod 57 can penetrate through the mounting piece 56 through the third positioning hole 512 and can be movably inserted into the toothed bar 51 through the second positioning hole 511; the dragging block 58 is arranged at the other end of the positioning rod 57, the diameter of the dragging block 58 is larger than the aperture of the third positioning hole 512, and the extension spring 59 is sleeved on the positioning rod 57 and connected between the mounting piece 56 and the dragging block 58.

The pulling block 58 is pulled outwards, the positioning rod 57 is pulled out of the second positioning hole 511, the locking between the rack bar 51 and the second supporting fence 2 is released, the length of the first supporting fence 1 and the length of the second supporting fence 2 can be adjusted through the rack bar 51 and the gear 54, and the extension spring 59 is extended. After the positioning is completed, the pulling block 58 is released, that is, the positioning rod 57 can be inserted and reset through the elastic reset of the extension spring 59, so that the positioning rod 57 is inserted into one of the second positioning holes 511, the toothed bar 51 and the mounting piece 56 are locked, and the first guardrail 1 and the second guardrail 2 are maintained at the specified splicing length.

Referring to fig. 1 to 5, the using method and the working principle of the present invention are:

through setting up stable subassembly 4, be convenient for carry out the altitude mixture control to the supporting construction that first guardrail 1 and second guardrail 2 are constituteed to satisfy the protection construction of the foundation ditch of the different degree of depth, concrete regulation mode is: the lug 47 is pulled upwards, the push rod 46 and the bolt 48 are driven to be lifted upwards synchronously, the fixed spring 45 is compressed under the force, and the bolt 48 is separated from the first positioning hole 49. The guide wheel 44 can be rotated, the rotating ring 43 rotates in the rotating ring groove 31 along with the guide wheel 44, and the rotating motion of the rotating guide wheel 44 is converted into the axial linear motion of the threaded column 41 through threads, so that the plugging length adjustment between the threaded column 41 and the support rod 3 is realized. After the adjustment is in place, the convex block 47 is released, the fixing spring 45 is reset, so that the bolt 48 is inserted downwards into one of the first positioning holes 49, the locking of the threaded column 41 is realized, and the bolt is stably supported at the bottom of the foundation pit through the base 42.

Through setting up adjusting device 5, be convenient for carry out length adjustment to the supporting construction that first guardrail 1 and second guardrail 2 are constituteed to satisfy the protection construction of the foundation ditch of different length, concrete regulation mode is: the retainer rod 57 is pulled out from the second positioning hole 511 by pulling the retainer block 58 outward, the extension spring 59 is extended, and the lock of the rack 51 is released. Can rotate runner 55, runner 55 drives gear 54 through axis of rotation 53 and rotates, thereby through meshing tooth transmission ratch 51, make the relative first guardrail 1 of second guardrail 2 remove, realize the length adjustment of second guardrail 2 and first guardrail 1, adjust the back that targets in place, release slipper 58, expanding spring 59 resets, drive locating lever 57 and insert to one of them second locating hole 511 of ratch 51, the realization is to the locking of ratch 51, thereby the first guardrail 1 of fixed connection and second guardrail 2.

The above description is only for the purpose of illustrating the preferred embodiments of the present invention and should not be taken as limiting the scope of the present invention, therefore, any modifications, equivalents, improvements and the like made within the spirit and principles of the present invention should be included in the scope of the present invention.

Claims (8)

1. The utility model provides a foundation ditch excavation supporting construction with adjustable, characterized by: comprises a first supporting guardrail (1), a second supporting guardrail (2), a supporting rod (3), a stabilizing component (4) and an adjusting component (5); the first supporting guardrail (1) and the second supporting guardrail (2) are of U-shaped structures with one open ends, and the open end of the first supporting guardrail (1) is connected with the open end of the second supporting guardrail (2) in an adjustable manner through an adjusting assembly (5); the upper ends of the support rods (3) are respectively and fixedly connected with the two sides of the sealing end of the first support guardrail (1) and the second support guardrail (2), and the upper ends of the stabilizing components (4) are respectively connected with the lower ends of the support rods (3) in an adjustable mode.

2. The adjustable excavation supporting structure of claim 1, wherein: each group of stabilizing assemblies (4) comprises a threaded column (41), a base (42), a rotating mechanism and a first positioning mechanism; the base (42) is in a conical structure with a narrow upper part and a wide lower part and is coaxially connected with the lower end of the threaded column (41); the support rod (3) is of a hollow tubular structure, the rotating mechanism is arranged at the bottom of the support rod (3), and the upper end of the threaded column (41) is in threaded connection with the rotating mechanism, so that the upper end of the threaded column (41) can be rotatably and adjustably coaxially inserted into the support rod (3); the first positioning mechanism is embedded in the pipe wall of the support rod (3) and movably inserted with the rotating mechanism.

3. The adjustable foundation pit excavation supporting structure of claim 2, characterized in that: the rotating mechanism comprises a rotating ring (43), a connecting ring (410) and a guide wheel (44); a rotating ring groove (31) is axially formed at the bottom of the supporting rod (3), the rotating ring (43) is rotatably embedded in the rotating ring groove (31), and the connecting ring (410) is coaxially connected with the rotating ring (43) and the guide wheel (44), so that the guide wheel (44) is positioned below the bottom of the supporting rod (3); the middle parts of the rotating ring (43), the connecting ring (410) and the guide wheel (44) are respectively provided with an internal thread matched with the threaded column (41), so that the threaded column (41) is screwed in the threads and penetrates through the rotating ring (43), the connecting ring (410) and the guide wheel (44); the first positioning mechanism is movably inserted on the guide wheel (44).

4. The adjustable excavation supporting structure of claim 3, wherein: the diameter of the rotating ring (43) is larger than that of the connecting ring (410) and smaller than that of the guide wheel (44), so that the rotating mechanism is in an I-shaped circular structure.

5. The adjustable excavation supporting structure of claim 3, wherein: the first positioning mechanism comprises a fixed spring (45), a push rod (46), a convex block (47) and a plug pin (48); an installation groove (32) is formed in the pipe wall of the supporting rod (3), the upper end of the fixed spring (45) is fixedly connected with the upper end of the installation groove (32), the lower end of the fixed spring (45) is fixedly connected with the upper end of the push rod (46), and the connecting push rod (46) can be elastically embedded in the installation groove (32) through the fixed spring (45); a sliding groove (33) communicated with the mounting groove (32) is formed on the pipe wall of the supporting rod (3), one end of a convex block (47) is arranged on the push rod (46), and the other end of the convex block (47) penetrates through the sliding groove (33) and extends to the outside of the supporting rod (3); the upper end of a bolt (48) is connected to the bottom of the connecting and pushing rod (46), a plurality of first positioning holes (49) are formed in the guide wheel (44) at intervals, and the lower end of the bolt (48) can be movably inserted into one of the first positioning holes (49).

6. The adjustable excavation supporting structure of claim 1, wherein: the adjusting assembly (5) comprises a rack bar (51), a rotating mechanism, a gear (54) and a second positioning mechanism; one end of the toothed bar (51) is fixedly connected with the end part of the opening end of the first branch guardrail (1), and an adjusting slot is formed in the opening end of the second branch guardrail (2), so that the other end of the toothed bar (51) can be inserted into the adjusting slot; the top of the open end of the second support guardrail (2) is provided with an engagement groove (510) communicated with the adjusting slot, and the gear (54) is rotatably arranged in the engagement groove (510) through a rotating mechanism, so that the gear (54) is engaged and connected with the toothed bar (51); the second positioning mechanism is arranged on the side part of the opening end of the second support guardrail (2), and the second positioning mechanism is movably inserted with the toothed bar (51).

7. The adjustable foundation pit excavation supporting structure of claim 6, characterized in that: the rotating mechanism comprises a mounting block (52), a rotating shaft (53) and a rotating wheel (55); the pair of mounting blocks (52) are fixedly mounted on the top surface of the opening end of the second support guardrail (2) respectively and are positioned on two sides of the meshing groove (510), two ends of the rotating shaft (53) can rotatably penetrate through the pair of mounting blocks (52), and the gear (54) is coaxially mounted on the rotating shaft (53) and is positioned between the pair of mounting blocks (52); the rotating wheel (55) is coaxially connected to one end of the rotating shaft (53).

8. The adjustable foundation pit excavation supporting structure of claim 6, characterized in that: the second positioning mechanism comprises a mounting piece (56), a positioning rod (57), a dragging block (58) and a telescopic spring (59); the mounting piece (56) is fixedly arranged at the end part of the opening end of the second support guardrail (2), a plurality of second positioning holes (511) are formed in the toothed bar (51) at intervals, a third positioning hole (512) is formed in the mounting piece (56), the third positioning hole (512) can be aligned with one of the second positioning holes (511), and one end of the positioning rod (57) can penetrate through the mounting piece (56) through the third positioning hole (512) and is movably inserted into the toothed bar (51) through the second positioning hole (511); the dragging block (58) is arranged at the other end of the positioning rod (57), the diameter of the dragging block (58) is larger than the aperture of the third positioning hole (512), and the telescopic spring (59) is sleeved on the positioning rod (57) and connected between the mounting piece (56) and the dragging block (58).

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