A recyclable method for lifting and dismantling prefabricated retaining walls of expanded foundation pits

Abstract

A recyclable method for lifting and dismantling prefabricated retaining walls in expanded-base foundation pits is disclosed. The method involves first constructing a pulley lifting platform and then dismantling the assembled retaining walls. During the dismantling process, two segments are used as a lifting group. The lifting ropes on the retaining wall rings of the lower segments within a lifting group are tied to a triangular lifting frame. After the lifting group is lifted to a certain height by a lifting device, the lifting group is moved and the lifting ropes of the segment are loosened. This step is repeated until all segments of the retaining walls are completely dismantled. Finally, post-construction site cleanup and retaining wall maintenance are performed. The present invention provides a recyclable method for lifting and dismantling prefabricated retaining walls in expanded-base foundation pits. The method involves lifting and dismantling the retaining walls from top to bottom, ensuring the stable dismantling and recycling of the prefabricated retaining wall foundation, thereby reducing the economic costs of geological disaster remediation projects.

Description

Technical Field

[0001] The invention relates to the technical field of geological disaster control engineering construction, and in particular to a recyclable method for lifting and removing assembled retaining walls of a bottom-enlarged foundation pit. Background Art

[0002] Most high-voltage transmission lines in my country inevitably cross mountainous and forested terrain. This poses a significant risk to the foundations of high-voltage transmission towers in the event of a landslide, mudslide, or other geological disaster. This could lead to the tower's collapse, potentially causing power outages or even forest fires, damaging the national economy. Therefore, how to quickly adjust and reinforce tower foundations or construct emergency towers after a geological disaster to prevent further risks is a pressing issue for the power sector.

[0003] The adjustment and reinforcement of the tower foundation or the establishment of the emergency repair tower cannot be separated from the use of foundation retaining walls, which can avoid deformation, collapse and water seepage of the hole wall during the foundation pit construction process, and ensure the personal safety of the construction workers to a certain extent. In geographical environments with traffic restrictions such as mountainous areas and forests, the line foundation is generally adjusted by manually excavating the foundation pit and pouring the retaining wall on site. This method brings many problems when facing mountain rescue work: 1) The construction period of the cast-in-place retaining wall is too long, which generally takes more than half of the time of the foundation pit excavation project, and the cast-in-place concrete foundation retaining wall cannot be put into use immediately. It must be cured to a certain strength before it can be used. This is not something that is welcomed at the emergency repair site where "time" is precious; 2) The foundation retaining wall composed of concrete is heavy, and it is very difficult to transport and install it by manpower, and large lifting equipment The equipment cannot be used normally due to the complex and rugged terrain environment in mountainous areas, which undoubtedly brings daunting challenges to mountain rescue work; 3) Traditional foundation retaining walls are rectangular or cylindrical, and are mostly suitable for excavation of pile foundation pits. They can only increase the depth of the foundation pit in the upper and lower ranges, but cannot widen the foundation pit in the left and right directions, that is, the foundation pit construction of the excavated foundation cannot be realized, which has certain limitations; 4) Foundation retaining walls cast on site generally do not involve demolition work, but are buried underground together with the foundation after pouring. This results in the consumption of corresponding material costs for each foundation built, which is not conducive to recycling.

[0004] In response to this, a large number of studies on the design and construction technology of foundation concrete retaining walls have emerged both at home and abroad, such as Hunan Electric Power - Volume 32 - Issue 5, author - Zhou Mingzhu, titled "Application of Steel Cylinder Retaining Wall Technology in Bored Pile Foundation Construction". The article proposes to use steel cylinder retaining walls to replace traditional foundation concrete retaining walls, and uses a portal-type boom lifting system to lift the pre-made steel cylinder into the foundation pit for construction. Since the on-site pouring and maintenance of concrete are omitted, the construction period is greatly shortened. However, the steel cylinder used in this method is as long as 3.5 meters, and the portal-type boom lifting system used is as high as 5.5 meters. This requires a sufficiently large and flat site for the construction site, which is not suitable for mountain rescue work. Secondly, the portal-type boom device used for lifting has a complex structure and takes a long time to assemble on site, which increases the time cost of rescue.

[0005] The article numbered 1671-9913(2020)S1-0088-04, "Research on the Design of a New Prefabricated Retaining Wall for Manually Excavated Foundations," is from CNKI. This design divides the foundation retaining wall into multiple cylindrical interlocking retaining wall components. This solves both the problem of the heavy concrete retaining wall and the difficulty of transporting it through mountainous terrain, as well as the long service life of cast-in-place concrete. However, this design relies on the bottom soil to support the retaining wall's weight, thereby achieving lateral widening of the foundation pit bottom. This cannot prevent the retaining wall from sinking during excavation, nor can it guarantee the safety of workers working on the site.

[0006] The patent application number is "202111041370.6", "Quick-installation rectangular pile hole prefabricated retaining wall and its installation method". Rectangular holes are pre-dug on each component of the retaining wall. When pouring the concrete foundation, the concrete can contact the original soil through the holes, thereby enhancing the overall vertical bearing capacity of the foundation. However, the design fails to take into account the lateral expansion of the holes and has poor versatility.

[0007] To sum up, the current foundation retaining walls have their own advantages and disadvantages, but basically no consideration is given to the demolition and recycling of the retaining walls. Most of them are buried underground together with the concrete foundation, and even bear the force of the superstructure together with the foundation. This will greatly increase the economic cost of the rescue work. Since the rescue foundation has been established when the demolition work is carried out, the demolition step will not increase the time cost of the rescue work. Summary of the Invention

[0008] The technical problem to be solved by the present invention is to provide a recyclable method for lifting and dismantling the prefabricated retaining wall of an expanded bottom foundation pit. Under the premise of ensuring recycling, the entire demolition work does not require excavation of the soil around the foundation, does not require a large area of ​​site, and does not damage the cast-in-place foundation and foundation retaining wall.

[0009] In order to solve the above technical problems, the technical solution adopted by the present invention is:

[0010] A recyclable method for lifting and dismantling assembled retaining walls of a bottom-enlarged foundation pit, comprising the following steps:

[0011] Step 1: Complete the installation and construction of the pulley lifting platform and triangular balance frame;

[0012] Step 2: Use n sections of retaining wall rings as a lifting group, where n = 1, 2, .... Since each section of retaining wall ring is 0.5m high, n is the number of retaining wall rings required according to the depth of the foundation pit; tie the three lifting ropes installed at the lifting ring of the uppermost lifting group and the lifting ring at the bottom end of the lifting group to the triangular balance frame respectively, and tie the three load-bearing steel wire ropes located at the single-wheel hook pulley to the midpoints of the three sides of the triangular balance frame. Manually adjust the position of the triangular balance frame, and manually tighten the traction wire rope with a capstan until the rope is straight; during this process, the load-bearing steel wire rope gradually relaxes, which has no effect on the lifting;

[0013] Step 3: After ensuring that all three lifting ropes are in a vertically taut state, continue to rotate the manual capstan steadily and slowly to lift until the uppermost retaining wall ring in the uppermost lifting group is 0.1m to 0.2m away from the top of the foundation pit; manually move the uppermost retaining wall ring in the lifting group to an open space on the side and untie the lifting ropes; repeat the above process, continue to rotate the manual capstan, and remove the other retaining wall rings in the lifting group in turn;

[0014] Step 4: Check whether there are any connecting pieces in the retaining wall channel that have been moved out of place or even stuck inside the channel during the lifting process. If so, use a magnet to clear the connecting pieces out of the channel in advance to avoid damaging the semi-solidified concrete foundation during the lifting process;

[0015] Step 5. After confirming that the channel is cleared, tie the three lifting ropes at the lifting ring of the bottom wall protection ring of the next lifting group to the triangular balance frame respectively. When the uppermost wall protection ring in the lifting group is 0.1m to 0.2m away from the top of the foundation pit, manually move the uppermost wall protection ring in the lifting group to an open space on the side and untie the lifting ropes; repeat the above process, continue to rotate the manual winch, and remove the other wall protection rings in the lifting group in turn;

[0016] Step 6. When the lifting height of the lifting group is greater than the maximum movable lifting height of the lifting device, the triangular balance frame needs to be replaced midway; when the triangular balance frame being hoisted is hoisted to the maximum lifting height, the triangular balance frame to be installed is manually assisted to connect the triangular balance frame to be installed with the ring on the lifting rope near the top of the foundation pit. Remove the load-bearing wire rope on the triangular balance frame being hoisted and fix it to the triangular balance frame to be installed; untie the lifting rope on the triangular balance frame being hoisted to separate the triangular balance frame being hoisted from the lifting rope; then transfer the traction wire rope fixed on the triangular balance frame being hoisted to the triangular balance frame to be installed. At this time, the triangular balance frame being hoisted is removed, and the installation of the triangular balance frame to be installed is completed, and the wall protection ring body can be lifted upward again.

[0017] Step 7: Repeat step 6 until the remaining lifting height of the lifting group is within the movable lifting height, and then lift the lifting group, recover and assemble the wall guard.

[0018] Step 8: Repeat steps 2 to 7 until all retaining wall rings except the hollow retaining wall ring and the circulation retaining wall ring are hoisted out of the foundation pit. The hollow retaining wall ring and the circulation retaining wall ring have been adhered to the foundation itself during the pouring of concrete to strengthen the bearing capacity of the foundation, so they cannot be recycled.

[0019] Step 9: After the above steps are completed, backfill the soil into the retaining wall channel and compact it with a tamping tool. After the project passes the inspection, the removal of the prefabricated retaining wall is completed.

[0020] Step 10: After the retaining wall removal work is completed, the construction site needs to be cleaned up.

[0021] In step 2, before the demolition work, a certain number of nail piles need to be driven around the foundation pit, and the lifting ropes of all lifting groups need to be tied to the nail piles and marked.

[0022] In step 1, the movable lifting height of the pulley lifting platform is h1. The length of the triangular balance frame's single side l is related to the foundation pit radius r. The calculation formula is as follows:

[0023]

[0024] Considering that the height of a single-segment retaining wall ring is 0.5m, and since a single-segment retaining wall ring can be moved by hand when it is 0.1m off the ground, it is necessary to ensure that the movable lifting height should be no less than 0.5m. With a certain margin, h1 is 0.6-1m; the pulley bracket angle α is between 45° and 75°; the pulley bracket height h2 is determined by the movable lifting height h1 and the angle α between the pulley bracket and the horizontal direction. The calculation formula of h2 is as follows:

[0025]

[0026] Since the pulley bracket root opening L4 must be larger than the foundation pit width and a certain margin is left for the upward lifting of the triangular balance frame, the calculation formula for L4 is as follows:

[0027] L4=h2 tanα

[0028] The pulley lifting platform includes a connecting seat, the lower end of which is fixed by supporting legs, and a fixed pulley hook is installed at the center of the connecting seat, and the fixed pulley hook is used to hang the single-wheel hook pulley; a manual winch is installed on the corresponding ground, one end of the traction wire rope is installed on the manual winch, and the other end is fixed on the triangular balance frame after passing through the pulley of the single-wheel hook pulley; a load-bearing steel wire rope is installed on the hook of the single-wheel hook pulley, and the other end of the load-bearing steel wire rope is fixed at the midpoint of the triangular balance frame.

[0029] The wall protection ring body in step 2 includes an arc-shaped plate, and multiple arc-shaped plates are spliced ​​into a wall protection ring body. A lifting ring is provided on the outside of each section of the wall protection ring body, and the lifting ring is connected to a lifting rope, which extends out of the foundation pit; multiple sections of the wall protection ring body are aligned up and down in turn through connecting pieces, tightly connected to form the wall protection body.

[0030] Positioning clamping parts are arranged on the left and right sides of the arc-shaped plate, and connecting holes are opened on the positioning clamping parts. Adjacent arc-shaped plates are spliced ​​through the positioning clamping parts and locked by bolts.

[0031] The arc-shaped plate is made of aluminum-magnesium alloy material.

[0032] At least one through hole is distributed on the side wall of the lowest section of the wall protection ring body, and the through hole is used for construction workers to carry out horizontal bottom expansion engineering; a section of the wall protection ring body adjacent to the wall protection ring body with the through hole is provided with a drainage hole.

[0033] The lifting rope is composed of multiple sections of steel wire ropes and rings, and adjacent steel wire ropes are connected by the rings.

[0034] The present invention provides a recyclable method for lifting and dismantling assembled retaining walls of a bottom-enlarged foundation pit, which has the following technical effects:

[0035] 1) The fabricated retaining wall is made of aluminum-magnesium alloy, which is lightweight, low-cost, and strong. This overcomes the shortcomings of traditional cast-in-place concrete, such as long service life, heavy weight, and poor transportation. Furthermore, aluminum-magnesium alloy has a high elastic modulus and good stress stability, making it less susceptible to instability and failure. This prefabricated structure is simple and convenient to assemble, and it does not occupy a large area. It is suitable for environments with many obstacles, such as mountainous areas and forests, and is highly suitable for emergency rescue in mountainous areas where every second counts.

[0036] 2) The hollowed-out design of the retaining wall at the bottom segment allows for excavation in all four directions of the foundation pit, meeting the excavation requirements of the expanded pit bottom and demonstrating strong applicability. When pouring concrete piles in the expanded pit, the through-holes in the porous retaining wall ring and the bottom retaining wall ring ensure that the concrete slurry is better poured into the expanded pit bottom and poured densely, thus ensuring the vertical bearing capacity of the expanded foundation.

[0037] 3) By setting a lifting ring on the outside of the wall protection ring, which can be connected to the lifting rope and matched with the corresponding lifting device, the wall protection ring can be lifted and recycled, realizing green economic development and filling the gap in the recycling and disassembly work of the basic wall protection construction technology.

[0038] 4) The use of vertical H-shaped connectors simplifies assembly of the entire retaining wall system, eliminating the need for bolt connections and shortening pit construction time. The curved structure and transition connectors are made of high-strength materials, ensuring the retaining wall ring has excellent load-bearing performance and high construction safety. The curved structure is also coated with a release agent to prevent demolding difficulties during re-hoisting.

[0039] 5) Adopting a top-down lifting and demolition method, without excavating the soil around the foundation, without requiring a large area of ​​site, and without damaging the cast-in-place foundation and assembled retaining wall, the stable demolition and recycling of the assembled retaining wall foundation is ensured, thereby reducing the economic cost of geological disaster remediation projects. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] The present invention will be further described below with reference to the accompanying drawings and examples:

[0041] Figure 1 Schematic diagram of the structure of the arc-shaped plate in the present invention (arc-shaped plate of a solid wall protection ring body).

[0042] Figure 2 Schematic diagram of the structure of the arc-shaped plate in the present invention (arc-shaped plate of the circulation wall protection ring).

[0043] Figure 3 Schematic diagram of the structure of the arc-shaped plate in the present invention (arc-shaped plate of the hollow wall protection ring).

[0044] Figure 4 It is a schematic diagram of the explosion after the wall protection ring body of the present invention is disassembled.

[0045] Figure 5 It is a cross-sectional view of the connecting piece in the present invention.

[0046] Figure 6 Schematic diagram of the installation of the connecting piece in the present invention.

[0047] Figure 7 It is a partial schematic diagram of the wall protection ring body after assembly in the present invention.

[0048] Figure 8 Schematic diagram of the working state of the present invention (the wall protection ring bodies are gradually removed in pairs).

[0049] Figure 9 Schematic diagram of the working state of the present invention (simplified pulley lifting platform part).

[0050] Figure 10 Schematic diagram of replacing the triangular balance frame in the present invention.

[0051] Figure 11 Schematic diagram of the pulley lifting platform in the present invention.

[0052] Figure 12 Schematic diagram of the connecting seat in the present invention.

[0053] Figure 13 Schematic diagram of the sling in the present invention.

[0054] Figure 14 This is a schematic diagram of the working state in which the triangular balance frame needs to be replaced in the present invention.

[0055] In the figure: wall protection ring body 1, arc-shaped plate 1.1, positioning clamping part 1.2, connecting hole 1.3, lifting ring 1.4, connecting piece 2, slot 2.1, hollow wall protection ring body 3, through hole 3.1, solid wall protection ring body 4, lifting rope 5, pulley lifting platform 6, connecting seat 6.1, support leg 6.2, fixed pulley hook 6.3, single-wheel hook block 6.4, manual capstan 6.5, traction wire rope 6.6, load-bearing wire rope 6.7, triangular balance frame 7, foundation steel frame 8, poured concrete 9, circulation wall protection ring body 10, lifting group 11. DETAILED DESCRIPTION

[0056] like Figure 1-6 As shown, a foundation pit bottom expansion foundation prefabricated retaining wall suitable for mountain rescue recycling includes a retaining wall ring body 1. Each section of the retaining wall ring body 1 is spliced ​​together by three arc-shaped plates 1.1. The arc length of the arc-shaped plate 1.1 is 5m, the thickness is 8mm, and the height is 500mm. Each arc-shaped plate 1.1 is provided with a positioning clamping part 1.2 on the left and right. The positioning clamping part 1.2 on one side is a groove and the positioning clamping part 1.2 on the other side is a protrusion. The groove and the protrusion can be clamped. A plurality of connecting holes 1.3 are vertically opened on the positioning clamping part 1.2. Adjacent arc-shaped plates 1.1 are spliced ​​together by the positioning clamping parts 1.2 and fixed by bolts. The upper and lower retaining wall ring bodies 1 are aligned and tightly connected by the connecting piece 2.

[0057] The wall protection ring body 1 is divided into a hollow wall protection ring body 3, a solid wall protection ring body 4 and a circulation wall protection ring body 10. The three are similar in that: the center position of the outer wall of the three is prefabricated with a lifting ring 1.4 in advance for binding and lifting, so as to realize the installation or disassembly of the assembled wall protection (the lifting ring 1.4 is connected to the lifting rope 5 for easy later disassembly). The three are different in that: the arc-shaped plate 1.1 of the hollow wall protection ring body 3 has equidistant hollow rectangular perforations 3.1, with a grid height of 0.4m and a width of 1.5m, for construction workers to carry out horizontal bottom expansion projects. The arc-shaped plate 1.1 of the solid wall protection ring body 4 is a solid structure. The circulation wall protection ring body 10 is covered with through holes.

[0058] like Figure 8 As shown, the hollow retaining ring 3 is a single piece and is placed at the lowest end of the foundation pit. Circular holes with a radius of 50mm are equidistantly cut out at the bottom of the flow retaining ring 10. This facilitates the flow of concrete into the expanded foundation pit during the subsequent pouring of the concrete foundation. The other stacked retaining rings 1 are all solid retaining rings 4.

[0059] The connecting piece 2 is made of H-shaped steel, and the H-shaped steel has slots 2.1 on the top and bottom. The slots 2.1 are connected and fitted with the wall protection ring body 1. Figure 4-5 As shown, 12 connecting pieces 2 are evenly distributed between each layer of wall protection ring bodies 1 , and the 12 connecting pieces 2 are used to align and fix the upper and lower wall protection ring bodies 1 .

[0060] A recyclable method for lifting and dismantling prefabricated retaining walls in a foundation pit with an expanded base. The specific construction operations are as follows:

[0061] 1. Construction of pulley lifting platform 6

[0062] 1. Construction of the pulley bracket

[0063] like Figure 11-12 As shown, the pulley bracket is composed of a connecting seat 6.1, a supporting leg 6.2, and a fixed pulley hook 6.3.

[0064] The connecting seat 6.1 is pre-welded from two transverse steel plates of different sizes and three vertical steel plates of equal size. The three vertical steel plates are connected on one side and equidistantly spaced 120 degrees apart on the other side. They are welded together to the larger transverse steel plate, and a smaller transverse steel plate is welded to the other end of the vertical steel plate.

[0065] A fixed pulley hook 6.3 is welded in advance at the center of the small transverse steel plate, and the fixed pulley hook 6.3 is used to accommodate a single-wheel hook pulley 6.4.

[0066] The support legs 6.2 are three equal-length support steel pipes, and docking plates are welded to the ends of the three equal-length support steel pipes in advance. The docking plates are connected to the connecting seat 6.1 by bolts. A fixing plate is welded to the other end of the support legs 6.2, and the fixing plate is connected to the ground by pile nails to fix the pulley lifting platform.

[0067] like Figure 14 As shown in the figure, the side length of the triangular balance frame is l, the movable lifting height is h1, the pulley bracket height is h2, and the pulley bracket root opening is L4.

[0068] The movable lifting height h1 of the pulley lifting platform is within a certain range. The length of the single side l of the triangular balance frame is related to the radius r of the foundation pit. The calculation formula is as follows:

[0069]

[0070] Considering that the height of a single-segment retaining wall ring is 0.5m, and since a single-segment retaining wall ring can be moved 0.1m above the ground, it is necessary to ensure that the movable lifting height should be no less than 0.5m, with a certain margin and a range of 0.6 to 1m;

[0071] The pulley bracket height h2 is determined by the movable lifting height h1, the angle α between the bracket and the horizontal direction, and the length of the single side of the triangular balance frame l, and its value is (unit: m):

[0072]

[0073] The pulley support angle α is between 45° and 75°;

[0074] The pulley bracket root opening L4 must be larger than the foundation pit width and leave a certain margin for the upward lifting of the triangular balance frame. Its value is (unit: m):

[0075] L4=h2 tanα

[0076] 2. Installation of pulley assembly and triangular balance frame

[0077] A manual capstan 6.5 is placed within a safe distance of the foundation pit. A perforated base plate is welded to the bottom of the capstan 6.5 and secured to the ground with stakes. Three strands of traction wire rope 6.6 are manually guided through the manual capstan 6.5 and the single-wheel hook block 6.4. The traction wire rope 6.6 on the manual capstan 6.5 side is completely wrapped around the grinding disc. The traction wire rope 6.6 on the single-wheel hook block 6.4 side is left with a length margin equal to the movable lifting height h1. The traction wire rope 6.6 is then separated into three strands. Several turns of wire rope are wrapped around the separated nodes for reinforcement. Each strand of traction wire rope 6.6 is secured to the corners of the triangular gimbal 7. One end of the load-bearing wire rope 6.7 is secured to the hook of the single-wheel hook block 6.4. The other end is similarly separated into three strands and secured to the midpoints of the three sides of the triangular gimbal 7. The pulley bracket is manually moved so that the center of the single-wheel hook block 6.4, the center of the triangular balance frame 7 and the center of the foundation pit are located on the same axis, and the pulley lifting platform is arranged.

[0078] The side length of the triangular balance frame 7 is equal to the side length of the inscribed triangle in the foundation pit. The maximum lifting height is the movable lifting height of the pulley lifting platform. Its function is to ensure that the lifting ropes are always lifted upward at the same time and length during demolition work.

[0079] Each corner point and the midpoint of the three sides of the triangular balancing frame 7 are welded with hooks for connecting with the rings on the suspension rope 5 and the traction wire rope 6.6 and the load-bearing wire rope 6.7.

[0080] 2. Dismantling of prefabricated retaining wall

[0081] When the concrete in the foundation pit is semi-solidified, you can start to disassemble the assembled retaining wall ring from top to bottom. Taking the 20-segment assembled retaining wall as an example, every two segments of retaining wall ring are regarded as a lifting group.

[0082] The specific disassembly steps are as follows:

[0083] During the installation of the retaining wall, a certain number of nail piles will be driven around the foundation pit, and the lifting rope 5 of each lifting group will be fixed on the nail piles and marked. This is to ensure that the lifting ropes of different lifting groups will not be mixed up during the lifting and removal of the retaining wall, and to prevent the lifting ropes from accidentally falling into the foundation pit during the removal process.

[0084] The lifting rope 5 is composed of multiple sections of wire rope and rings, with adjacent wire ropes connected by rings. A ring is strung along the end of the lifting rope 5 connected to the triangular gimbal 7, while the end of the lifting rope 5 connected to the wall protection ring 1 is not strung along with a ring. Rings are connected to the wire rope at regular intervals in the middle section to facilitate replacement of the triangular gimbal 7 during subsequent dismantling work.

[0085] When the concrete poured in the foundation pit is cured to a semi-solidified state, the assembled retaining wall ring of the expanded bottom foundation pit can be removed from top to bottom. Taking the assembled retaining wall of the 20-segment expanded bottom foundation pit as an example, the disassembly process is as follows: Figure 8-9 As shown in the figure, the lifting rope 5 is represented by L1, L2, L3... in sequence, the wall protection ring body 1 is represented by P0, P1, P2, P3... in sequence, and the standard section during the disassembly and assembly process is 2 sections.

[0086] The specific steps involved in the removal method are as follows:

[0087] (1) Determine the lifting group to be removed and loosen the corresponding lifting rope 5 fixed on the nail pile, that is, first lift the P in the uppermost lifting group of the prefabricated retaining wall of the expanded bottom foundation pit. 19 3-strand lifting rope L on the lifting ring 1.4 of the segmental wall protection ring 10 They are respectively hung on the hooks of the triangular balancing frame 7, and the position of the triangular balancing frame 7 is adjusted manually. The manual capstan 6.5 tightens the traction wire rope 6.6 until the suspension rope 5 is in a taut state;

[0088] (2) After determining the three lifting ropes L 10 After all are in a taut state and kept vertical, continue to rotate the manual winch 6.5 to slowly and steadily lift the lifting group until the upper segment wall ring (P 20 ) was lifted about 0.1m from the top of the foundation pit and manually moved P 20 From the retaining wall ring to the open space around the foundation pit;

[0089] (3) Continue to rotate the manual winch 6.5 to the lower segment wall ring in the same lifting group (P 19 ) was lifted about 0.1m from the foundation pit surface and manually moved P 19 The wall ring is removed and 19 The lifting rope L on the wall protection ring and the triangular balance frame 7 10 ;

[0090] (4) During the process of lifting the lifting group upward, the manual winch is always rotated smoothly and at a uniform speed, and the lifting rope is always kept in a vertical and taut state, so as to ensure that the wall protection ring does not tilt during the lifting process, and to prevent the H-shaped steel connecting piece 2 from being carried away from its original position or even stuck inside the channel during the lifting process, thereby damaging the semi-solidified concrete foundation;

[0091] (5) After confirming that there is no debris in the wall protection lifting channel, move the P 17 The lifting rope L9 on the wall protection ring is hung on the triangular balance frame 7. 18 、P 17 After being hoisted to 0.1m from the top of the foundation pit, the retaining wall rings and lifting ropes are manually moved and the retaining wall is recovered and assembled;

[0092] (6) When the lifting height of the wall protection ring body 1 is greater than the movable lifting height h1 (h1 is Figure 14 (marked in the middle), it is necessary to replace the triangular balance frame 7 midway; if Figure 10 As shown, the triangular gimbal 7 being hoisted is designated A, and the triangular gimbal 7 to be installed is designated B. After A is hoisted to height h1, B is manually connected to the ring 5.1 on the hoisting rope 5 near the top of the foundation pit. The load-bearing wire rope 6.7 is removed from A and secured to B. At this point, the load-bearing wire rope 6.7 is straightened.

[0093] Note: The load-bearing wire rope 6.7 is in a relaxed state when it reaches the maximum movable distance, and is only straightened due to the supporting effect when it is replaced. That is, when the traction wire rope 6.6 is straightened and bears the load, the load-bearing wire rope 6.7 is relaxed; when the traction wire rope 6.6 is not bearing the load, the load-bearing wire rope 6.7 is straightened and bears the load).

[0094] (7) Figure 10As shown, untie the lifting rope 5 on A to separate A from the lifting rope 5, rotate the manual capstan in the opposite direction, loosen the traction wire rope 6.6, move the traction wire rope 6.6 downward, and transfer the traction wire rope 6.6 to B. Subsequently, A is removed, B is installed, and the wall protection ring can be lifted upward again.

[0095] Note: Tie the load-bearing wire rope 6.7 to B to play a supporting role (during the replacement process, that is, from the transfer of the load-bearing wire rope 6.7 to B to the transfer of the traction wire rope 6.6 to B, the load-bearing wire rope 6.7 is always stretched straight), so as to prevent the lifting group from falling as the traction wire rope 6.6 is relaxed.

[0096] (8) Repeat steps (6) to (7) until the remaining lifting height of the wall protection ring is less than the movable lifting height h1. The specific replacement process is as follows: Figure 6 As shown; after the replacement is completed, continue with the lifting, manually move the wall protection ring, lifting rope, and recycle and assemble the wall protection.

[0097] (9) Repeat steps (2) to (8) until all the retaining wall rings above the hollow retaining wall ring 3 and the circulation retaining wall ring 10 are hoisted out of the foundation pit. At this time, the hollow retaining wall ring 3 and the circulation retaining wall ring 10 have been adhered to the foundation itself during the pouring of concrete and do not need to be recycled.

[0098] (10) After the above steps are completed, backfill the soil into the retaining wall channel and compact the soil with a tamping tool. After the project passes the inspection, the removal of the prefabricated retaining wall is completed.

[0099] In order to ensure the smooth progress of the retaining wall removal work, the prefabricated retaining wall of the expanded bottom foundation pit needs to be surface-smoothed during production to reduce burrs on the surface of the retaining wall ring and increase smoothness. At the same time, before pouring concrete, a release agent needs to be evenly applied to the inner surface of the prefabricated retaining wall to prevent the poured concrete from sticking to the prefabricated retaining wall to be lifted and removed.

[0100] 3. Post-construction site care and wall maintenance

[0101] After the retaining wall removal work is completed, the construction site needs to be cleaned up.

[0102] The post-processing includes the removal of the wall protection ring. Since the solid wall protection ring is composed of three solid arc-shaped plates, the carried wall protection ring needs to be further dismantled. The construction workers use a wrench to remove the bolts, dismantle the wall protection ring into the arc-shaped plates before assembly and stack them together.

[0103] The post-processing includes the recovery of auxiliary connectors, counting the number of bolts and H-shaped steel connectors to avoid missing them at the construction site, and checking the use of auxiliary connectors. If any damage occurs, they should be replaced in time. After the inventory is completed, the auxiliary connectors should be stored in the tool box for easy recycling.

[0104] The post-processing work includes dismantling the pulley lifting platform, loosening the traction wire rope wrapped around the grinding disc, removing the triangular balance frame and the connected traction wire rope and load-bearing wire rope from the pulley side, removing the fixed pulley bracket and the nail pile of the manual winch in turn, storing and organizing all traction, demolition and load-bearing wire ropes, recovering the manual winch and single-wheel hook pulley, and loading them for transportation.

[0105] The wall protection maintenance treatment includes the cleaning of the curved plates. The aforementioned demolition work involves applying a release agent on the surface of the aluminum-magnesium alloy to prevent the wall protection from adhering to the cast-in-place concrete. Therefore, the release agent attached to the surface of the wall protection needs to be cleaned before storage: the recovered curved plates are evenly rinsed with a detergent and then rinsed several times with clean water.

Claims

1. A recyclable method for lifting and dismantling prefabricated retaining walls in a foundation pit, comprising the following steps: Step 1: Complete the installation and construction of the pulley lifting platform (6) and the triangular balance frame (7); Step 2: Take n sections of wall protection ring as a lifting group, tie the three lifting ropes (5) installed at the lifting group on the top layer and at the lifting ring (1.4) of the wall protection ring (1) at the bottom of the lifting group to the corner points of the triangular balance frame (7), tie the three load-bearing steel wire ropes (6.7) located at the single-wheel hook pulley (6.4) to the midpoints of the three sides of the triangular balance frame (7), manually adjust the position of the triangular balance frame (7), and tighten the traction steel wire rope (6.6) with a manual winch (6.5) until the lifting rope (5) is straight; Step 3: After confirming that all three lifting ropes (5) are in a vertically taut state, continue to rotate the manual winch (6.5) to steadily and slowly lift; until the upper end wall protection ring (1) in the uppermost lifting group is 0.1m to 0.2m away from the top of the foundation pit; manually move the upper end wall protection ring (1) in the lifting group to an open space on the side; continue to rotate the manual winch (6.5) to remove the lower end wall protection ring (1) in the lifting group and untie the lifting rope (5); Step 4: Check whether the connecting piece (2) in the wall protection channel is carried away from its original position or even stuck inside the channel during the lifting process. If so, use a magnet to clear the connecting piece (2) out of the channel in advance to avoid scratching the semi-solidified concrete foundation during the lifting process; Step 5: After confirming that the channel has been cleared, tie the three lifting ropes (5) at the lifting ring (1.4) of the bottom wall protection ring (1) of the next lifting group to the triangular balance frame (7) respectively, repeat step 3, and when the uppermost wall protection ring (1) of the lifting group is 0.1m to 0.2m away from the top of the foundation pit, manually move the upper wall protection ring (1) of the lifting group to an open space on the side; continue to rotate the manual winch (6.5) to remove the other wall protection rings (1) in the lifting group in turn; Step 6: When the lifting height of the lifting group is greater than the maximum lifting height of the lifting device, the triangular balance frame (7) needs to be replaced midway; when the triangular balance frame (7) being hoisted is hoisted to the maximum lifting height, the triangular balance frame (7) to be installed is connected to the ring on the lifting rope (5) near the top of the foundation pit with manual assistance; the load-bearing steel wire rope (6.7) on the triangular balance frame (7) being hoisted is removed and fixed on the triangular balance frame (7) to be installed; the lifting rope (5) on the triangular balance frame (7) being hoisted is untied to separate the triangular balance frame (7) being hoisted from the lifting rope (5); then the traction steel wire rope (6.6) fixed on the triangular balance frame (7) being hoisted is transferred to the triangular balance frame (7) to be installed. At this time, the triangular balance frame (7) being hoisted is removed, and the installation of the triangular balance frame (7) to be installed is completed, and the wall protection ring body can be hoisted upward again; Step 7: Repeat step 6 until the remaining lifting height of the lifting group is less than the movable lifting height, and then lift the lifting group, recover it, and assemble the retaining wall; Step 8: Repeat steps 2 to 7 until all the retaining wall rings (1) except the hollow retaining wall ring (3) and the circulation retaining wall ring (10) are hoisted out of the foundation pit. The hollow retaining wall ring (3) and the circulation retaining wall ring (10) are now adhered to the foundation itself with the pouring of concrete to strengthen the bearing capacity of the foundation, and therefore cannot be recycled; Step 9: After the above steps are completed, backfill the soil into the retaining wall channel and compact the soil with a tamping tool; after the project passes the inspection, the dismantling of the assembled retaining wall is completed; Step 10: After the retaining wall removal work is completed, the construction site needs to be cleaned up.

2. A recyclable method for lifting and dismantling assembled retaining walls of a foundation pit according to claim 1, characterized in that: In step 2, before the demolition work, a certain number of nail piles need to be driven around the foundation pit, and all the lifting ropes (5) of the lifting group need to be tied to the nail piles and marked.

3. The recyclable method for lifting and dismantling prefabricated retaining walls of a foundation pit according to claim 1 is characterized in that: In step 1, the movable lifting height of the pulley lifting platform (6) is h1, and the length of one side of the triangular balance frame is l It is related to the foundation pit radius r, and the calculation formula is as follows: Considering that the height of a single-segment retaining wall ring is 0.5m, and since a single-segment retaining wall ring can be moved 0.1m above the ground, it is necessary to ensure that the movable lifting height should be no less than 0.5m. With a certain margin, h1 is 0.6~1m; the pulley bracket angle α is between 45° and 75°; the pulley bracket height h2 is determined by the movable lifting height h1 and the angle α between the pulley bracket and the horizontal direction. The calculation formula of h2 is as follows: Since the pulley bracket root opening L4 must be larger than the foundation pit width and a certain margin is left for the upward lifting of the triangular balance frame, the calculation formula of L4 is as follows: 。 4. The recyclable method for lifting and removing the prefabricated retaining wall of a foundation pit according to claim 1 is characterized in that: The pulley lifting platform (6) includes a connecting seat (6.1), the lower end of the connecting seat (6.1) is supported and fixed by a support leg (6.2), a fixed pulley hook (6.3) is installed at the center of the connecting seat (6.1), and the fixed pulley hook (6.3) hangs the single-wheel hook block (6.4); a manual winch (6.5) is installed on the corresponding ground, one end of the traction wire rope (6.6) is installed on the manual winch (6.5), and the other end is fixed to the triangular balance frame (7) after passing through the pulley of the single-wheel hook block (6.4); a load-bearing wire rope (6.7) is installed on the hook of the single-wheel hook block (6.4), and the other end of the load-bearing wire rope (6.7) is fixed to the midpoint of the triangular balance frame (7).

5. The method for lifting and removing the recyclable prefabricated retaining wall of a foundation pit according to claim 1 is characterized in that: The wall protection ring body (1) in step 2 comprises an arc-shaped plate member (1.1), wherein a plurality of arc-shaped plate members (1.1) are spliced ​​together to form the wall protection ring body (1), and a lifting ring (1.4) is provided on the outside of each section of the wall protection ring body (1), wherein the lifting ring (1.4) is connected to a lifting rope (5), and the lifting rope (5) extends outside the foundation pit; the plurality of sections of the wall protection ring body (1) are aligned up and down in sequence through the connecting piece (2), are tightly connected, and form the wall protection body.

6. The recyclable method for lifting and removing the prefabricated retaining wall of a foundation pit according to claim 5 is characterized in that: Positioning clamping parts (1.2) are arranged on the left and right sides of the arc-shaped plate (1.1), and connecting holes (1.3) are opened on the positioning clamping parts (1.2). Adjacent arc-shaped plate members (1.1) are spliced ​​together through the positioning clamping parts (1.2) and locked by bolts.

7. The recyclable method for lifting and removing prefabricated retaining walls of a foundation pit according to claim 5, characterized in that: The arc-shaped plate (1.1) is made of an aluminum-magnesium alloy material.

8. The recyclable method for lifting and removing prefabricated retaining walls of a foundation pit according to claim 5 is characterized in that: At least one perforation (3.1) is distributed on the side wall of the lowest section of the wall protection ring body (1), and the perforation (3.1) is used by construction workers to carry out horizontal bottom expansion work; and a drainage hole (3.2) is provided on the wall protection ring body (1) adjacent to the wall protection ring body (1) with the perforation (3.1).

9. The recyclable method for lifting and removing prefabricated retaining walls of a foundation pit according to claim 5, characterized in that: The suspension rope (5) is composed of multiple sections of steel wire ropes and circular rings, and adjacent steel wire ropes are connected by circular rings.

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