Full assembly type foundation pit supporting structure and supporting method thereof

Abstract

The application discloses a full-assembly foundation pit supporting structure and a supporting method thereof. The supporting structure comprises a steel sheet pile, the steel sheet pile is arranged around the inner periphery of a foundation pit, a plurality of L-shaped corbels are arranged at intervals along the inner periphery of the steel sheet pile, the vertical plate of each L-shaped corbel is detachably connected to the inner side of the steel sheet pile, the horizontal plates of the plurality of L-shaped corbels are located at the same elevation, a plurality of steel enclosing purlins are supported on the horizontal plates of the plurality of L-shaped corbels on each side of the foundation pit and are arranged around the inner periphery of the steel sheet pile, a pair of struts and an angle strut are arranged for limiting the steel enclosing purlins, the pair of struts are arranged between two steel enclosing purlins on opposite sides and the two ends of the pair of struts are respectively abutted to the two steel enclosing purlins on opposite sides, the angle strut is arranged at each corner of the foundation pit and the two ends of the angle strut are respectively abutted to two steel enclosing purlins on adjacent sides, the pair of struts and the angle strut are adjustable in length, and the supporting effect is improved by arranging the supporting structure.

Description

Technical Field

[0001] This invention relates to the field of foundation pit support technology, and in particular to a fully prefabricated foundation pit support structure and its support method. Background Technology

[0002] For foundation pits with large spans or deep depths, foundation pit support is necessary to maintain stability during excavation and construction. Currently, existing foundation pit support typically employs a combination of sheet piles, steel walers, and in-pit bracing: after driving the sheet piles, steel walers are welded to the inner circumference of the sheet piles, and then in-pit bracing is welded between the walers on opposite sides. This construction method requires custom-made in-pit bracing based on the pit's dimensions, resulting in poor practicality. Furthermore, the fully welded connection makes installation, dismantling, and relocation difficult. Additionally, this type of foundation pit support only provides reaction force when the pit shows a tendency to collapse inwards, leading to poor support effectiveness. Summary of the Invention

[0003] The purpose of this invention is to overcome the defects of the prior art and provide a fully prefabricated foundation pit support structure and its support method, which facilitates the installation, dismantling and turnover of foundation pit support, and also improves the foundation pit support effect.

[0004] To achieve the above objectives, the technical solution adopted by this invention is a fully prefabricated foundation pit support structure, comprising:

[0005] Sheet piles, wherein the sheet piles are arranged around the inner perimeter of the foundation pit;

[0006] Multiple L-shaped brackets are spaced apart along the inner circumference of the sheet pile. The vertical plate of each L-shaped bracket is detachably connected to the inner side of the sheet pile. The horizontal plates of the multiple L-shaped brackets are all located at the same elevation and face away from the sheet pile.

[0007] Multiple steel walers are respectively supported on the horizontal plates of multiple L-shaped brackets on each side of the foundation pit and are arranged around the inner periphery of the steel sheet pile;

[0008] The bracing and corner bracing are used to limit the movement of the steel walers. The bracing is arranged between two steel walers on opposite sides and its two ends abut against the two steel walers on opposite sides, so as to abut the corresponding steel waler against the vertical plate of the corresponding L-shaped bracket. The corner bracing is arranged at each corner of the foundation pit and its two ends abut against two steel walers on adjacent sides, so as to abut the corresponding steel waler against the vertical plate of the corresponding L-shaped bracket. The lengths of both the bracing and the corner bracing are adjustable.

[0009] A further improvement of the fully prefabricated foundation pit support structure of the present invention is that the bracing and the corner bracing each include a first I-beam, a first connecting plate, and an end bearing box, wherein: the first connecting plate is connected to the first end of the first I-beam and is used to detachably connect to one of the steel walers; the end bearing box is slidably sleeved on the second end of the first I-beam and is used to detachably connect to the other steel waler; and a limiting member for limiting the end bearing box is connected between the end bearing box and the first I-beam.

[0010] A further improvement of the fully prefabricated foundation pit support structure of the present invention is that the end bearing box includes a C-shaped plate and a rib plate connected between the two flange plates of the C-shaped plate. The rib plate is also connected to the web plate of the C-shaped plate. The web plate of the C-shaped plate is detachably connected to the steel waler. The two flange plates and the rib plate of the C-shaped plate are hollow structures, and the hollow portions of the two flange plates of the C-shaped plate are connected to the hollow portions of the rib plate to form an I-shaped groove for the first I-beam to be movably inserted. The limiting member includes a limiting pin. A first insertion hole for the limiting pin is opened on the top flange plate of the C-shaped plate. A plurality of second insertion holes for the limiting pin to be selectively inserted are opened at intervals along the length direction on the top flange plate of the first I-beam.

[0011] A further improvement of the fully prefabricated foundation pit support structure of the present invention is that the corner brace further includes two second connecting plates, which are respectively hinged to the first connecting plate of the corner brace and the end bearing box, and the two second connecting plates are respectively detachably connected to the corresponding steel waler.

[0012] A further improvement of the fully prefabricated foundation pit support structure of the present invention is that the steel waler is a second I-beam. In the limited state of the steel waler, the first flange plate of the steel waler abuts against the vertical plate of the L-shaped bracket, and the second flange plate is supported by the bracing or the corner bracing. A force transmission box is detachably connected to the steel waler at the position corresponding to each bracing or corner bracing. The force transmission box rests on the web of the steel waler and is clamped between the first flange plate and the second flange plate.

[0013] A further improvement of the fully prefabricated foundation pit support structure of the present invention is that a plug plate for filling the first gap between the steel waler and the protrusion of the steel sheet pile is detachably connected to the steel waler, and a first hook for hanging on the first flange plate is connected to one side of the plug plate, and the thickness of the plug plate is adapted to the first gap.

[0014] A further improvement of the fully prefabricated foundation pit support structure of the present invention is that a plug box for filling the second gap between the steel waler and the recess of the steel sheet pile is detachably connected to the steel waler, and the thickness of the plug box is adjustable.

[0015] A further improvement of the fully prefabricated foundation pit support structure of the present invention is that the plug box includes:

[0016] Box;

[0017] A second hook is used to hang on the first flange plate, and the second hook is connected to one side of the box body;

[0018] An L-shaped insert plate is used to insert into the other side of the box. The box has a third insertion hole for inserting the horizontal plate of the L-shaped insert plate, and the vertical plate of the L-shaped insert plate extends upward.

[0019] Multiple thickened plates are used to selectively clamp between the vertical plate of the L-shaped insert and the box body to adjust the thickness of the plug box.

[0020] A fully prefabricated foundation pit support method includes the following steps:

[0021] Step 1: Provide the above-mentioned fully prefabricated foundation pit support structure;

[0022] Step 2: Drive steel sheet piles around the outer perimeter of the designed location of the foundation pit;

[0023] Step 3: Excavate the first layer of soil in the foundation pit down to below the design installation elevation of the steel waler;

[0024] Step 4: Connect the vertical plates of multiple L-shaped brackets to the inner circumference of the sheet pile at intervals, so that the horizontal plates of the multiple L-shaped brackets are at the same elevation and facing away from the sheet pile.

[0025] Step 5: Support the steel walers on the cross plates of the L-shaped brackets on each side of the foundation pit;

[0026] Step 6: Adjust the length of the bracing, and place the two ends of the bracing against the two steel walers on opposite sides, and place the corresponding steel walers against the vertical plates of the multiple L-shaped brackets;

[0027] Step 7: Adjust the length of the corner brace, and place both ends of the corner brace against the two adjacent steel walers on both sides, and place the corresponding steel walers against the vertical plates of the multiple L-shaped brackets;

[0028] Step 8: Continue excavating the foundation pit until the bottom of the pit reaches the designed elevation.

[0029] Compared with the prior art, the advantages of the present invention are:

[0030] 1. All connections between structures are detachable, facilitating the installation, dismantling, and relocation of the entire foundation pit support.

[0031] 2. The lengths of the bracing and the corner bracing can be adjusted to accommodate foundation pits of various sizes. Attached Figure Description

[0032] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0033] Figure 1 This is a schematic diagram showing the usage state of the fully prefabricated foundation pit support structure of the present invention.

[0034] Figure 2 This is a schematic diagram of the L-shaped bracket of the fully prefabricated foundation pit support structure of the present invention.

[0035] Figure 3 This is a detailed structural drawing of the fully prefabricated foundation pit support structure of the present invention.

[0036] Figure 4 This is a detailed structural drawing of the bracing structure of the fully prefabricated foundation pit support structure of the present invention.

[0037] Figure 5 This is a detailed structural drawing of the end bearing box of the fully assembled foundation pit support structure of the present invention.

[0038] Figure 6 This is a schematic diagram of the hinge connection of the second connecting plate of the fully prefabricated foundation pit support structure of the present invention.

[0039] Figure 7 This is a top view of the connection state of the plug plate in the fully assembled foundation pit support structure of the present invention.

[0040] Figure 8 This is a front view of the connection status of the plug box and plug plate in the fully assembled foundation pit support structure of the present invention.

[0041] Figure 9 This is a top view of the connection state of the plug box in the fully assembled foundation pit support structure of the present invention.

[0042] Figure 10 This is a detailed structural drawing of the plug box of the fully assembled foundation pit support structure of the present invention.

[0043] Figure 11 This is a front view of the connection state of the force transmission box in the fully assembled foundation pit support structure of the present invention.

[0044] In the diagram: 1. Sheet pile; 2. Steel waler; 3. Bracing; 301. First I-beam; 302. First connecting plate; 303. End bearing box; 3031. C-shaped plate; 3032. Rib plate; 3033. I-shaped groove; 3034. Limiting pin; 304. Baffle plate; 305. Second connecting plate; 306. First ear plate; 307. Second ear plate; 308. Pin shaft; 4. Angle brace; 5. L-shaped bracket; 6. Plug plate; 7. Plug box; 701. Box body; 702. Second hook; 703. L-shaped insert plate; 704. Thickened plate; 705. Insert rod; 706. Third insertion hole; 8. Force transmission box. Detailed Implementation

[0045] The following specific examples illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention.

[0046] The fully prefabricated foundation pit support structure and its support method of the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0047] Please see Figures 1 to 11 As shown, the fully prefabricated foundation pit support structure includes:

[0048] Sheet pile 1, which is installed around the inner perimeter of the foundation pit;

[0049] Multiple L-shaped brackets 5 are spaced along the inner periphery of the sheet pile 1. The vertical plate of each L-shaped bracket 5 is detachably connected to the inner side of the sheet pile 1. The horizontal plates of the multiple L-shaped brackets 5 are all located at the same elevation and are opposite to the sheet pile 1.

[0050] Multiple steel walers 2 are supported on the horizontal plates of multiple L-shaped brackets 5 on each side of the foundation pit and are arranged around the inner periphery of the steel sheet pile 1.

[0051] The bracing 3 and the corner bracing 4 are used to limit the steel waler 2. The bracing 3 is set between the two steel walers 2 on opposite sides and its two ends abut against the two steel walers 2 on opposite sides, so as to abut the steel waler 2 against the vertical plate of the L-shaped bracket 5. The corner bracing 4 is set at each corner of the pit and its two ends abut against the two steel walers 2 on adjacent sides, so as to abut the steel waler 2 against the vertical plate of the L-shaped bracket 5. The lengths of the bracing 3 and the corner bracing 4 are adjustable.

[0052] Preferably, both the bracing 3 and the corner bracing 4 include a first I-beam 301, a first connecting plate 302, and an end bearing box 303, wherein: the first connecting plate 302 is connected to the first end of the first I-beam 301 and is used to detachably connect to one of the steel walers 2; the end bearing box 303 is slidably sleeved on the second end of the first I-beam 301 and is used to detachably connect to the other steel waler 2; and a limiting member for limiting the end bearing box 303 is connected between the end bearing box 303 and the first I-beam 301.

[0053] Specifically, the first connecting plate 302 is bolted to the corresponding steel waler 2.

[0054] By adjusting the lengths of the bracing 3 and the corner bracing 4, it can be adapted to foundation pits of various sizes, thus improving its practicality.

[0055] Preferably, the end bearing box 303 includes a C-shaped plate 3031 and a rib 3032 connected between the two flanges of the C-shaped plate 3031. The rib 3032 is also connected to the web of the C-shaped plate 3031. The web of the C-shaped plate 3031 is detachably connected to the steel waler 2. Both flanges of the C-shaped plate 3031 and the rib 3032 are hollow structures, and the hollow portions of the two flanges of the C-shaped plate 3031 are hollow. All of them are connected to the hollow part of the rib plate 3032 to form an I-shaped groove 3033 for the first I-beam 301 to be movably inserted. The limiting member includes a limiting pin 3034. The top flange of the C-shaped plate 3031 is provided with a first insertion hole for the limiting pin 3034 to be inserted. The top flange of the first I-beam 301 is provided with a plurality of second insertion holes spaced along the length direction for the limiting pin 3034 to be selectively inserted.

[0056] Specifically, through holes are provided on the end faces of the two flanges of the C-shaped plate 3031 and the rib plate 3032, and each through hole is connected to the corresponding hollow part.

[0057] The first I-beam is slidably inserted into the I-beam groove 3033 through the through holes on the two flanges of the C-shaped plate 3031 and the end face of the rib plate 3032.

[0058] Specifically, the web of the C-shaped plate 3031 is connected to the corresponding steel waler 2 by bolts.

[0059] Specifically, it also includes a jack for adjusting the length of the brace 3 or the corner brace 4 and applying prestress. A baffle 304 is connected to the first I-beam 301 at a position relatively close to the end bearing box 303. The baffle 304 is connected between the two flanges of the first I-beam 301. An installation chamber for installing the jack is formed between the baffle 304 and the web of the C-shaped plate 3031.

[0060] By controlling the extension of the jack, the end bearing box 303 and the first I-beam 301 slide in opposite directions, so that the first I-beam 301 and the end bearing box 303 respectively abut against the corresponding steel waler 2. Then, the position of the end bearing box 303 is limited by the limiting pin 3034, and the jack is removed, so that the two ends of the bracing 3 or the corner bracing 4 always have a relative outward pushing force, which improves the foundation pit support effect.

[0061] Preferably, the corner brace 4 further includes two second connecting plates 305, which are respectively hinged to the first connecting plate 302 and the end bearing box 303 of the corner brace 4, and are respectively detachably connected to the corresponding steel waler 2.

[0062] Specifically, the second connecting plate 305 is connected to the steel waler 2 by bolts.

[0063] Specifically, the end bearing box 303 or the first connecting plate 302 is connected to the corresponding second connecting plate 305 by a pin 308. A second ear plate 307 is connected to one side of the second connecting plate 305. Two first ear plates 306 are connected at intervals to the side of the end bearing box 303 or the first connecting plate 302 opposite to the first I-beam 301. A space is formed between the two first ear plates 306 for accommodating the second ear plate 307. Connecting holes for the pin 308 are provided on the two first ear plates 306 and the second ear plate 307.

[0064] Preferably, the steel waler 2 is a second I-beam. In the limited state of the steel waler 2, the first flange plate of the steel waler 2 abuts against the vertical plate of the L-shaped bracket 5, and the second flange plate is supported by the brace 3 or the corner brace 4. A force transmission box 8 is detachably connected to the steel waler 2 at the position corresponding to each brace 3 or corner brace 4. The force transmission box 8 is placed on the web of the steel waler 2 and clamped between the first flange plate and the second flange plate.

[0065] By setting up the force transmission box 8, the force transmission effect of the steel waler 2 is ensured, while also preventing the bracing 3 or the corner bracing 4 from bending the second flange plate, which would affect the force transmission and subsequent reuse.

[0066] Preferably, a plug plate 6 is detachably connected to the steel waler 2 for filling the first gap between the steel waler 2 and the protrusion of the steel sheet pile 1. A first hook for hanging on the first flange plate is connected to one side of the plug plate 6. The thickness of the plug plate 6 is adapted to the first gap.

[0067] Specifically, the vertical plate of the L-shaped bracket 5 is bolted to the protrusion of the sheet pile 1.

[0068] Since not every protrusion of the sheet pile 1 is connected to the L-shaped bracket 5, a first gap is formed between the steel waler 2 and the protrusions that are not connected to the L-shaped bracket 5 when the steel waler 2 is in the restricted state. By setting the plug plate 6 to fill the first gap, the contact area between the steel waler 2 and the sheet pile 1 is increased, thereby increasing the force transmission area and improving the stability of the foundation pit.

[0069] Preferably, the steel waler 2 is detachably connected to a plug box 7 for filling the second gap between the steel waler 2 and the recess of the steel sheet pile 1, and the thickness of the plug box 7 is adjustable.

[0070] By connecting a plug box 7 between the recess of the steel waler 2 and the steel sheet pile 1 to fill the second gap, the contact area between the steel waler 2 and the steel sheet pile 1 is increased, thereby increasing the force transmission area and improving the stability of the foundation pit.

[0071] Preferably, the plug box 7 includes:

[0072] Box 701;

[0073] The second hook 702 is used to hang on the first flange plate and is connected to one side of the box 701;

[0074] An L-shaped insert plate 703 is used to insert into the other side of the housing 701. The housing 701 has a third insertion hole 706 for inserting the horizontal plate of the L-shaped insert plate 703. The vertical plate of the L-shaped insert plate 703 extends upward.

[0075] Multiple thickened plates 704 are used to selectively clamp between the vertical plate of the L-shaped insert 703 and the box body 701 to adjust the thickness of the plug box 7.

[0076] By clamping a corresponding number of thickened plates 704 between the vertical plate of the L-shaped insert 703 and the box body 701, the overall thickness of the plug box 7 is adjusted, thereby improving its practicality.

[0077] Specifically, the vertical plate of the L-shaped insert plate 703 is also connected to two insert rods 705 for insertion into the box body 701. The box body 701 is provided with a fourth insertion hole for inserting the insert rods 705. The two insert rods 705 are spaced apart in the horizontal direction, and the horizontal distance between the two insert rods 705 is not less than the width of the thickened plate 704.

[0078] By setting the insertion rod 705, the connection stability of the L-shaped insertion plate 703 is enhanced, and by limiting the horizontal distance between the two insertion rods 705, conflict with the thickened plate 704 is avoided.

[0079] A fully prefabricated foundation pit support method includes the following steps:

[0080] Step 1: Provide the above-mentioned fully prefabricated foundation pit support structure;

[0081] Step 2: Drive steel sheet piles 1 around the outer perimeter of the designed location of the foundation pit;

[0082] Step 3: Excavate the first layer of soil in the foundation pit down to below the design installation elevation of the steel waler 2;

[0083] Step 4: Connect the vertical plates of multiple L-shaped brackets 5 to the inner circumference of the sheet pile 1 at intervals, so that the horizontal plates of multiple L-shaped brackets 5 are at the same elevation and opposite to the sheet pile 1.

[0084] Step 5: Support the multiple steel walers 2 on the horizontal plates of the multiple L-shaped brackets 5 on each side of the foundation pit;

[0085] Step 6: Adjust the length of the brace 3, and abut the two ends of the brace 3 against the two steel walers 2 on opposite sides, and abut the steel walers 2 against the vertical plates of the multiple L-shaped brackets 5;

[0086] Step 7: Adjust the length of the corner brace 4, and abut the two ends of the corner brace 4 against the two adjacent steel walers 2, and abut the corresponding steel walers 2 against the vertical plates of the multiple L-shaped brackets 5;

[0087] Step 8: Continue excavating the foundation pit until the bottom of the pit reaches the designed elevation.

[0088] It should be noted that the structures, proportions, sizes, etc., illustrated in the accompanying drawings are merely for illustrative purposes to aid those skilled in the art and to facilitate understanding and reading. They are not intended to limit the scope of the invention and therefore have no substantial technical significance. Any modifications to the structure, changes in proportions, or adjustments to size, without affecting the effectiveness and purpose of the invention, should still fall within the scope of the technical content disclosed herein. Furthermore, the terms "upper," "lower," "left," "right," "middle," and "one" used in this specification are merely for clarity and not intended to limit the scope of the invention. Changes or adjustments to their relative relationships, without substantially altering the technical content, should also be considered within the scope of the invention.

[0089] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make some modifications or alterations to the above-disclosed technical content to create equivalent embodiments without departing from the scope of the technical solution of the present invention. Any simple modifications, equivalent changes and alterations made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solution of the present invention shall still fall within the scope of the technical solution of the present invention.

Claims

1. A fully prefabricated foundation pit support structure, characterized in that, include: Sheet piles, wherein the sheet piles are arranged around the inner perimeter of the foundation pit; Multiple L-shaped brackets are spaced apart along the inner circumference of the sheet pile. The vertical plate of each L-shaped bracket is detachably connected to the inner side of the sheet pile. The horizontal plates of the multiple L-shaped brackets are all located at the same elevation and face away from the sheet pile. Multiple steel walers are respectively supported on the horizontal plates of multiple L-shaped brackets on each side of the foundation pit and are arranged around the inner periphery of the steel sheet pile; The bracing and corner bracing are used to limit the movement of the steel walers. The bracing is positioned between two steel walers on opposite sides, with both ends abutting against the two steel walers on opposite sides, so that the corresponding steel waler abuts against the vertical plate of the corresponding L-shaped bracket. The corner bracing is positioned at each corner of the foundation pit, with both ends abutting against two steel walers on adjacent sides, so that the corresponding steel waler abuts against the vertical plate of the corresponding L-shaped bracket. Both the bracing and the corner bracing are adjustable in length. Each corner brace includes a first I-beam, a first connecting plate, and an end bearing box. The first connecting plate is connected to the first end of the first I-beam and is detachably connected to one of the steel walers. The end bearing box is slidably fitted onto the second end of the first I-beam and is detachably connected to the other steel waler. A limiting member for limiting the end bearing box is connected between the end bearing box and the first I-beam. The end bearing box includes a C-shaped plate and ribs connecting the two flanges of the C-shaped plate. The plate, the rib plate is also connected to the web of the C-shaped plate, the web of the C-shaped plate is detachably connected to the steel waler, the two flange plates and the rib plate of the C-shaped plate are hollow structures, and the hollow portions of the two flange plates of the C-shaped plate are connected to the hollow portions of the rib plates to form an I-shaped groove for the first I-beam to be movably inserted. The limiting member includes a limiting pin, and the top flange plate of the C-shaped plate has a first insertion hole for the limiting pin to be inserted. The top flange plate of the first I-beam... The upper waler is provided with a plurality of second insertion holes spaced apart along its length for selective insertion of the limiting pin. The steel waler is a second I-beam. In the limited state of the steel waler, the first flange plate of the steel waler abuts against the vertical plate of the L-shaped bracket, and the second flange plate is supported by the bracing or the corner bracing. A force transmission box is detachably connected to the steel waler at the position corresponding to each bracing or corner bracing. The force transmission box rests on the web of the steel waler and is clamped between the first flange plate and the second flange plate.

2. The fully prefabricated foundation pit support structure as described in claim 1, characterized in that, The corner brace also includes two second connecting plates, which are respectively hinged to the first connecting plate of the corner brace and the end bearing box, and the two second connecting plates are respectively detachably connected to the corresponding steel waler.

3. The fully prefabricated foundation pit support structure as described in claim 1, characterized in that, A plug plate is detachably connected to the steel waler for filling the first gap between the steel waler and the protrusion of the steel sheet pile. A first hook for hanging on the first flange plate is connected to one side of the plug plate. The thickness of the plug plate is adapted to the first gap.

4. The fully prefabricated foundation pit support structure as described in claim 1, characterized in that, A plug box for filling the second gap between the steel waler and the recess of the steel sheet pile is detachably connected to the steel waler, and the thickness of the plug box is adjustable.

5. The fully prefabricated foundation pit support structure as described in claim 4, characterized in that, The plug box includes: Box; A second hook is used to hang on the first flange plate, and the second hook is connected to one side of the box body; An L-shaped insert plate is used to insert into the other side of the box. The box has a third insertion hole for inserting the horizontal plate of the L-shaped insert plate, and the vertical plate of the L-shaped insert plate extends upward. Multiple thickened plates are used to selectively clamp between the vertical plate of the L-shaped insert and the box body to adjust the thickness of the plug box.

6. A fully prefabricated foundation pit support method, characterized in that, Including the following steps: Step 1: Provide the fully prefabricated foundation pit support structure as described in claim 1; Step 2: Drive steel sheet piles around the outer perimeter of the designed location of the foundation pit; Step 3: Excavate the first layer of soil in the foundation pit down to below the design installation elevation of the steel waler; Step 4: Connect the vertical plates of multiple L-shaped brackets to the inner circumference of the sheet pile at intervals, so that the horizontal plates of the multiple L-shaped brackets are at the same elevation and facing away from the sheet pile. Step 5: Support the steel walers on the cross plates of the L-shaped brackets on each side of the foundation pit; Step 6: Adjust the length of the bracing, and place the two ends of the bracing against the two steel walers on opposite sides, and place the corresponding steel walers against the vertical plates of the multiple L-shaped brackets; Step 7: Adjust the length of the corner brace, and place both ends of the corner brace against the two adjacent steel walers on both sides, and place the corresponding steel walers against the vertical plates of the multiple L-shaped brackets; Step 8: Continue excavating the foundation pit until the bottom of the pit reaches the designed elevation.

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