Underground diaphragm wall post-cast strip construction method based on cover and excavation reverse method

Abstract

The invention discloses an underground diaphragm wall post-cast strip construction method based on a cover and excavation reverse method, and relates to the technical field of subway underground construction, comprising the following steps of: dividing an underground post-cast strip into a plurality of sections from top to bottom in sequence; the method comprises the following steps: firstly, excavating a post-cast strip at the uppermost section, and excavating a placing groove in the outer side surface of the post-cast strip; a low-carbon steel plate is mounted at the bottom of the post-cast strip close to the placement groove; then a plurality of I-shaped steel is sequentially stacked in the containing groove from bottom to top, and a rigid soil retaining structure is formed; the adjacent I-shaped steels are welded in sequence; after the rigid soil retaining structure on the uppermost section is formed, a second section of post-cast strip below the rigid soil retaining structure is excavated, and the steps S2-S4 are repeated; and finally, the whole is poured. By the adoption of the scheme, the rigid soil retaining structure replaces a post-cast strip to conduct slope soil retaining, more working faces are provided for construction of the post-cast strip, and therefore the post-cast strip can be rapidly poured and formed, the construction speed of the underground diaphragm wall post-cast strip during cover and excavation reverse construction is greatly increased, and the construction period is shortened.

Description

Technical Field

[0001] The invention relates to the technical field of subway underground construction, and in particular to a construction method for a post-cast strip of an underground continuous wall based on a cover-and-excavation reverse approach. Background Art

[0002] During the construction of subway underground structures, many urban underground pipeline facilities are often encountered, such as communication pipelines, voltage lines, sewage pipes and other municipal facilities. Under normal circumstances, in order to better protect high-voltage lines and sewage pipes, these two pipelines are usually buried deep underground. In order not to affect the current traffic, subway construction often adopts the construction method of cover excavation and reverse construction. When the construction of subway underground continuous walls is built in areas with dense residential buildings, there is no space for the relocation of pipelines. Therefore, when constructing underground continuous walls at this time, pipeline facilities such as sewage pipes and high-voltage lines must be avoided, thus forming the post-casting belt of underground continuous wall construction.

[0003] Normally, the construction plan for the underground continuous wall post-casting strip is to first excavate it and pre-embed the ground-connected wall connectors on both sides of the post-casting strip, then tie the steel bars, and then pour the concrete. The next section of the post-casting strip can only be excavated and constructed after the concrete strength reaches the specified strength. Usually, the construction process of the post-casting strip is to pour the concrete in sections of 1.5m. While waiting for the concrete strength to rise, the next section of the post-casting strip cannot be excavated, tied with steel bars, and poured, which seriously lags behind the progress of the on-site work and wastes time. Summary of the invention

[0004] The present invention aims to solve the deficiencies in the prior art and aims to provide a method for constructing a post-cast strip of an underground continuous wall based on a cover-excavation and reverse construction method. By adopting this scheme, a rigid retaining structure is used instead of a post-cast strip to carry out slope retaining, thereby providing more working surfaces for the construction of the post-cast strip, so that the post-cast strip can be quickly cast and formed, greatly improving the construction speed of the post-cast strip of the underground continuous wall during the cover-excavation and reverse construction, and shortening the construction period.

[0005] The present invention is achieved through the following technical solutions:

[0006] A construction method for underground continuous wall post-casting strip based on the cover-excavation reverse method comprises the following steps:

[0007] S1: Divide the underground post-casting belt into several sections from top to bottom;

[0008] S2: First, excavate the uppermost post-casting strip, and excavate a placement groove on the outer side of the post-casting strip. The height of the placement groove is flush with the post-casting strip, and the horizontal cross-sectional size of the placement groove is adapted to the size of the I-beam;

[0009] S3: Install a low-carbon steel plate at the bottom of the post-cast strip near the placement groove, wherein the low-carbon steel plate is connected to the side wall of the post-cast strip;

[0010] S4: Subsequently, a plurality of I-beams are stacked in sequence from bottom to top in the placement groove to form a rigid retaining structure; one side flange of the I-beam at the bottom is welded to the low-carbon steel plate, and the other side flange is used to support the outer side surface of the placement groove; adjacent I-beams are welded in sequence;

[0011] S5: After the uppermost rigid retaining structure is formed, the second post-casting strip below is excavated, and steps S2-S4 are repeated from top to bottom until the construction of all segmented rigid retaining structures is completed;

[0012] S6: Finally, pour the entire post-cast strip.

[0013] In the prior art, in the common post-casting strip construction method, the post-casting strip is a gap with the same depth as the underground continuous wall, which cannot be completed by one-time steel bar binding and one-time concrete pouring, and needs to be poured in layers. When the cover-excavation reverse method is adopted, the pouring construction of the next layer can only be carried out after the post-casting strip of the upper layer is completed. Under normal circumstances, the construction of each layer of post-casting strip requires segmented steel bar binding and segmented pouring; and the strength of the concrete needs to reach at least 70%. Even if an early strength agent is used, it takes at least 3 days to excavate a layer of post-casting strip. During this period, the working surface can only be idle, which is undoubtedly very disadvantageous for projects with tight construction schedules. The present invention provides a construction method for the post-casting strip of an underground continuous wall based on the cover-excavation reverse method. By adopting this scheme, a rigid retaining structure is used instead of the post-casting strip to carry out slope retaining, providing more working surfaces for the construction of the post-casting strip, so that the post-casting strip can be quickly cast and formed, greatly improving the construction speed of the post-casting strip of the underground continuous wall during the cover-excavation reverse construction, and shortening the construction period.

[0014] In the specific scheme, the underground post-casting belt is first divided into several sections from top to bottom through the conventional cover-excavation reverse method, the post-casting belt of the uppermost section is excavated, and a placement groove is excavated on the outer side of the post-casting belt, so as to reserve space for placing the rigid retaining structure through the placement groove, and then a low-carbon steel plate is installed at the bottom of the post-casting belt near the end of the placement groove, so that the low-carbon steel plate and the side wall of the post-casting belt are fixedly connected. In this way, the bottom of the rigid retaining structure can be fixed by the low-carbon steel plate, which can not only improve the retaining capacity of the rigid retaining structure, but also facilitate It will not fall when the lower layer is excavated; then several I-beams are placed in the placement slot from bottom to top, the flange of the bottom I-beam is welded to the low-carbon steel plate, and the end of the upper I-beam flange is placed on the end of the lower I-beam flange and spot welded. In this way, the I-beam can be supported by the welding points at both ends of itself, thereby forming a stable retaining structure. In addition, the flange welding on the other side of the I-beam can form a closed retaining surface, which is not only conducive to grouting in the gap outside the retaining surface, but also prevents soil and mud from leaking. When the uppermost rigid retaining structure is formed, the second section of the post-casting strip below is then excavated, and the above steps are repeated from top to bottom until all the segmented rigid retaining structures are completed; finally, the overall post-casting strip can be poured. Through the above scheme, it is not necessary to wait until the post-cast strip forms sufficient strength for retaining soil before carrying out the next section of construction. Instead, a rigid retaining structure is used on the outside of the post-cast strip to replace the retaining soil, so that the excavation process from top to bottom and the steel bar binding steps can be carried out first, and finally the entire post-cast strip can be cast and formed, which greatly improves the construction efficiency of the post-cast strip.

[0015] A further solution is to adapt the size of the I-beam and make the retaining surface of the I-beam larger than the outer side of the post-cast strip, both ends of the placement groove extend beyond the two side walls of the post-cast strip, and the excavation depth of the placement groove is adapted to the distance between the two flanges of the I-beam; the widths of the two ends of the placement groove are adapted to the width of the I-beam.

[0016] A further solution is to avoid blocking the steel bar connector and affecting the steel bar binding between the two side walls of the post-cast strip, the low-carbon steel plate is connected to the side walls of the post-cast strip by anchor bolts, and a groove for the steel bar connector to pass through is opened on the low-carbon steel plate.

[0017] A further solution is to install a pulley hoisting device on the top wall of the post-cast strip to facilitate the transportation of the I-beams and low-carbon steel plates, and the pulley hoisting device is used to hoist the low-carbon steel plates and I-beams.

[0018] A further solution is to isolate the bearing surface of the I-beam from the soil, thereby facilitating the filling of the gap and improving the soil retaining capacity. The S4 further includes the following specific steps:

[0019] S41: placing an I-beam at the bottom of the placement groove, and welding a flange of one side of the I-beam to the low-carbon steel plate;

[0020] S42: On the bottom I-beam, stack a plurality of I-beams in sequence from bottom to top, and spot weld adjacent I-beams to form a rigid retaining structure;

[0021] S43: Then, a mild steel plate is placed between the top of the rigid retaining structure and the top of the placement groove to separate them;

[0022] S44: pouring concrete in the gap between the other side flange of the rigid retaining structure and the placement groove until the poured concrete seeps out, completing the construction of the first layer of the rigid retaining structure; after the poured concrete strength is formed, the next layer construction can be carried out.

[0023] A further solution is to facilitate the pouring of shotcrete to fill the gap between the rigid retaining structure and the soil. The flanges on the other side of the rigid retaining structure and the other side of the rigid retaining structure and the low-carbon steel plates on the top are all sealed and welded; and a through hole is left at the top for the grouting pipe to extend into.

[0024] A further solution is to facilitate the upper and lower connections to form an integrated retaining structure. In step S5, after the outer side surface of the next section of the post-cast strip is excavated to place the groove, the soil in the bottom gap of the upper layer of rigid retaining structure needs to be removed until the concrete poured in the previous section is exposed; and a pulley lifting device is installed at the bottom of the upper layer of rigid retaining structure.

[0025] A further solution is to weld stiffening ribs on both side flanges of the bottom I-beam in order to improve the structural rigidity of the bottom I-beam.

[0026] A further solution is to avoid municipal pipelines when setting up rigid retaining structures. When encountering municipal pipeline facilities during the construction of several rigid retaining structures from top to bottom:

[0027] Low carbon steel plates need to be installed on both the upper and lower sides of the pipeline, and both the upper and lower low carbon steel plates are connected to the side walls of the post-casting belt;

[0028] Subsequently, when constructing the rigid retaining structure, the rigid retaining structure is disconnected at the location where it passes through the municipal pipeline, and the I-beam flanges on the upper and lower sides of the municipal pipeline are welded to the low-carbon steel plates on the upper and lower sides respectively.

[0029] A further solution is to improve the construction efficiency. In step S5, when the construction process of several rigid retaining structures is carried out in sequence from top to bottom, steel bars are simultaneously tied at the post-cast strips of the completed rigid retaining structures.

[0030] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0031] The present invention provides a method for constructing a post-cast strip of an underground continuous wall based on a cover-excavation-reverse construction method. By adopting this scheme, a rigid retaining structure is used instead of a post-cast strip to perform slope retaining, thereby providing more working surfaces for the construction of the post-cast strip. The excavation process and the steel bar binding steps from top to bottom can be performed first, and finally the entire post-cast strip can be cast and formed, so that the post-cast strip can be quickly cast and formed, thereby greatly improving the construction speed of the post-cast strip of the underground continuous wall during the cover-excavation-reverse construction and shortening the construction period.

[0032] The present invention provides a method for constructing a post-cast strip of an underground continuous wall based on a cover-excavation reverse approach. By adopting this scheme, through the coordination of low-carbon steel plates and I-beams, municipal pipelines can be quickly avoided when setting up a rigid retaining structure, thereby shortening the construction period.

[0033] The present invention provides a construction method of underground continuous wall post-casting strip based on the cover-excavation reverse method. With this scheme, since the strength of the grouting between the I-beam and the soil can be formed in only 4 hours, time is greatly saved, and while constructing the next layer of rigid retaining structure, the steel bars of the upper layer of post-casting strip can be tied synchronously, which not only does not cause the idleness of the working surface, but also forms a flow construction. Since there is no need for layered post-casting strip retaining, as long as the rigid retaining structure is constructed fast enough, even if the strength of the concrete of the upper layer of concrete post-casting strip has not been formed, there is a working surface to tie the steel bars of the next layer of post-casting strip, which greatly improves the work efficiency and greatly shortens the construction period. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] In order to more clearly illustrate the technical solutions of the exemplary embodiments of the present invention, the following briefly introduces the drawings required for use in the embodiments. It should be understood that the following drawings only illustrate certain embodiments of the present invention and should not be regarded as limiting the scope. For those of ordinary skill in the art, other relevant drawings can be obtained based on these drawings without creative work. In the drawings:

[0035] Figure 1 A side cross-sectional view of the post-casting strip provided by the present invention;

[0036] Figure 2 A top view of the post-casting strip provided by the present invention;

[0037] Figure 3 A schematic diagram of hoisting an I-beam using a pulley hoisting device provided by the present invention;

[0038] Figure 4 A schematic diagram of the positions of the bottom I-beam and the low-carbon steel plate provided by the present invention;

[0039] Figure 5 A schematic diagram of a spliced ​​rigid retaining structure provided by the present invention;

[0040] Figure 6 A schematic diagram of a rigid retaining structure spliced ​​to the top provided by the present invention;

[0041] Figure 7 A schematic diagram of the hoisting of the next layer of I-beams provided by the present invention;

[0042] Figure 8 A schematic diagram of pouring the next layer provided by the present invention;

[0043] Fig. 9 A schematic diagram of the arrangement of a rigid retaining structure for avoiding municipal wire pipes provided by the present invention.

[0044] Marks and corresponding parts names in the attached drawings:

[0045] 1- post-cast strip, 2- placement trough, 3- mild steel plate, 4- I-beam, 5- steel bar connector, 6- pulley lifting device, 7- rigid retaining structure. DETAILED DESCRIPTION

[0046] In order to make the objectives, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with embodiments and drawings. The exemplary embodiments of the present invention and their description are only used to explain the present invention and are not intended to limit the present invention.

[0047] Example

[0048] The present embodiment discloses a construction method of an underground continuous wall post-casting strip 1 based on a cover-excavation reverse method, wherein I-beams 4 are inserted between the post-casting strip 1 and the retaining surfaces of the underground continuous walls on both sides, and a retaining structure is formed by welding and stacking the I-beams 4. The height of the inserted I-beams 4 also strictly follows the segmentation standard of the post-casting strip 1, 1.5m per section, and the I-beams 4 are connected by welding. The upper and lower sides of the stacked rigid retaining structure 7 are isolated from the soil by low-carbon steel, and the I-beams 4 contacting the soil are sprayed with plain concrete to isolate the soil. Since the strength of the sprayed anchor concrete is relatively fast, the next 1.5 m of the rigid retaining structure 7. At the same time, the post-cast strip 1 located on the excavation surface of the I-beam 4 can be used for tying steel bars. Once the rigid retaining structure 7 is built, the steel bars of the post-cast strip 1 can be tied. In this way, since the I-beam 4 is retaining the earth, the strength of the post-cast strip 1 is not needed to form a retaining wall, which increases the working surface for the construction of the post-cast strip 1 and allows the construction of the next section to proceed without waiting for the concrete strength to be formed. In this way, the speed of the post-cast strip 1 of the underground continuous wall during the cover-excavation reverse construction is greatly improved, shortening the construction period, and is particularly suitable for the construction of underground continuous walls that are in a tight schedule.

[0049] like Figure 1-Figure 9 As shown, the following specific steps are included:

[0050] First, the area enclosed by the ground-connected walls is excavated to facilitate excavation of the post-casting strip 1 from the inside to the outside, so as to avoid affecting the external buildings of the ground-connected walls;

[0051] After excavating the enclosed area, dig 1.5m deep from the previously poured top concrete, and dig a 320m wide placement groove 2 behind the ground-connected wall, that is, on the outer side of the post-casting strip 1; over-dig 200mm at both ends of the placement groove 2 to make the distance between the two ends of the placement groove 2 greater than the distance between the two side walls of the post-casting strip 1; so as to provide enough space for the later insertion of the I-beam 4, such as Figure 1 and Figure 2 shown.

[0052] Then, four holes for anchor bolts are pre-drilled on the low-carbon steel plate 3, and anchored on the previously poured underground continuous wall, that is, anchored on the side wall of the post-cast strip 1. Holes are pre-drilled on the low-carbon steel plate 3 at the position of the pre-buried steel bar connector 5 of the previously built ground continuous wall to form a C-shape, so as to facilitate the later binding of steel bars and pouring of concrete; Figure 1 shown.

[0053] Then prepare the bottom I-beam 4 and weld the stiffening ribs on both sides of the flange of the bottom I-beam 4; install the pulley hoisting device 6 on the previously poured upper concrete. Install the pulley device, and according to the design standard, hoist the bottom I-beam 4 prepared in advance to the designated position. After hoisting the I-beam 4 to the designated position, weld the bottom I-beam 4 to the low-carbon steel plate 3 to fix the position of the bottom I-beam 4, such as Figure 3 and Figure 4 shown.

[0054] Then, the remaining I-beams 4 are hoisted to the designated positions step by step from bottom to top using the pulley device, and all the hoisted I-beams 4 are connected by spot welding to form a rigid retaining structure 7. The I-beam 4 and the side to be retained are kept level with the plane of the I-beam 4 by grouting. Figure 5 and Figure 6 shown.

[0055] The last I-beam 4 is hoisted and installed, and a piece of low-carbon steel is welded on the top of the I-beam 4 to block the gap between the I-beam 4 and the soil to be retained, and grouting is continued between the I-beam 4 and the soil to be retained until the grouting concrete flows out of the gap between the I-beam 4 and the soil to be retained. The soil can be isolated from the soil by low-carbon steel on the upper and lower sides of the superimposed rigid retaining structure 7, and the I-beam 4 contacting the soil is sprayed with plain concrete to isolate the soil.

[0056] In this way, the first layer of rigid retaining structure 7 is completed, and then the retaining structure of the second layer of I-beam 4 is constructed. Since the construction of the post-casting strip 1 is cast in layers according to 1.5m, the retaining structure of the I-beam 4 also follows the layered construction of the post-casting strip 1. After the strength of the previous layer of grouting is formed, the next layer can be excavated.

[0057] Continue to dig 1.5m deep under the previously installed rigid retaining structure 7, and over-dig the placement groove 2 by 320mm at the outer edge of the underground continuous wall that has been built. At the same time, dig 200mm more soil pits on both sides of the underground continuous wall to leave enough space for the later installation of I-beams 4. Remove the soil in the gap of the upper layer of rigid retaining structure 7 until the grouting concrete poured in the previous stage is exposed.

[0058] Drill four anchor bolt holes on the low-carbon steel plate 3 in advance, and make holes on the steel plate where the ground-connected wall pre-embeds the steel bar connector 5, and fix the steel plate to the cast ground-connected wall. At the same time, prepare the bottom layer of I-beams 4 and weld the stiffening ribs on the flange side of the I-beams 4. Install the pulley hoisting device 6 on the welded iron plate of the upper layer, hoist the bottom layer of I-beams 4 to the specified position, and weld them to the steel plate. Then hoist the remaining I-beams 4 to the specified position in turn using the pulley hoisting device 6, and the I-beams 4 are welded and stabilized once in the form of spot welding. Then use grouting to fill the gap between the I-beams 4 and the retaining wall until the top I-beam 4. Weld the steel plate to the newly installed I-beams 4 and the previously installed I-beams 4 to fill the gap, and make grouting holes on the steel plate for grouting, weld and seal the steel plate to prevent grouting leakage during the grouting project. Then grouting is carried out between the steel plate and the soil being blocked until the grouting comes out from the other side. Figure 7 and Figure 8 shown.

[0059] Repeat the above operation process. When encountering municipal pipeline facilities, such as high-pressure pipelines and sewage pipes, you only need to weld 25mm thick iron plates on both sides of the pipeline facilities in advance to protect the pipeline facilities. The other operation processes are basically the same as the above steps. Low-carbon steel plates 3 need to be set on both sides of the pipeline. The low-carbon steel plates 3 on both sides are connected to the side walls of the post-cast strip 1; then when constructing the rigid retaining structure 7, disconnect the rigid retaining structure 7 at the location where it passes through the municipal pipeline, and weld the flanges of the I-beams 4 on the upper and lower sides of the municipal pipeline to the low-carbon steel plates 3 on the upper and lower sides respectively. Fig. 9 shown.

[0060] By repeating the above operation process, the rigid retaining structure 7 running through the entire post-cast zone 1 is completed.

[0061] According to the present invention, through the above steps, since the strength of the grouting between the I-beam 4 and the soil can be formed in only 4 hours, this greatly saves time, and while constructing the next layer of rigid retaining structure 7, the steel bars of the upper layer of post-casting strip 1 are tied, which not only does not cause the idleness of the working surface, but also forms a continuous construction. Since there is no need to retain the soil with layered post-casting strip 1, as long as the rigid retaining structure 7 is constructed fast enough, even if the strength of the concrete of the upper layer of concrete post-casting strip 1 has not been formed, there is a working surface to tie the steel bars of the next layer of post-casting strip 1, which greatly improves the work efficiency and greatly shortens the construction period.

[0062] The specific implementation methods described above further illustrate the objectives, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above description is only a specific implementation method of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A construction method for underground continuous wall post-casting strip based on the cover-excavation reverse method, characterized in that: The following steps are involved: S1: Divide the underground post-casting belt (1) into several sections from top to bottom; S2: First, excavate the uppermost post-casting strip (1), and excavate a placement groove (2) on the outer side of the post-casting strip (1), wherein the height of the placement groove (2) is flush with the post-casting strip (1), and the horizontal cross-sectional size of the placement groove (2) is compatible with the size of the I-beam (4); S3: installing a low-carbon steel plate (3) at the bottom of the post-cast strip (1) near the placement groove (2), wherein the low-carbon steel plate (3) is connected to the side wall of the post-cast strip (1); S4: Subsequently, a plurality of I-beams (4) are stacked in sequence from bottom to top in the placement groove (2) to form a rigid retaining structure (7); a flange on one side of the I-beam (4) at the bottom is welded to the low-carbon steel plate (3), and a flange on the other side is used to support the outer side surface of the placement groove (2); adjacent I-beams (4) are welded in sequence; S5: After the uppermost rigid retaining structure (7) is formed, the second post-casting strip (1) below is excavated, and steps S2-S4 are repeated from top to bottom until the construction of all the segmented rigid retaining structures (7) is completed; S6: Finally, pour the entire post-cast strip (1).

2. The method for constructing underground continuous wall post-casting strips based on the cover-excavation reverse construction method according to claim 1 is characterized in that: Both ends of the placement groove (2) extend beyond the two side walls of the post-cast strip (1), and the excavation depth of the placement groove (2) is matched to the distance between the two flanges of the I-beam (4); the widths of both ends of the placement groove (2) are matched to the width of the I-beam (4).

3. The construction method of underground continuous wall post-casting strip based on the cover-excavation reverse method according to claim 1 is characterized in that: The low-carbon steel plate (3) is connected to the side wall of the post-cast strip (1) via anchor bolts, and a groove for a steel bar connector (5) to pass through is formed on the low-carbon steel plate (3).

4. The method for constructing underground continuous wall post-casting strips based on the cover-excavation reverse construction method according to claim 1 is characterized in that: A pulley hoisting device (6) is installed on the top wall of the post-cast strip (1), and the pulley hoisting device (6) is used to hoist the low-carbon steel plate (3) and the I-beam (4).

5. The method for constructing underground continuous wall post-casting strips based on the cover-excavation reverse construction method according to claim 1 is characterized in that: The S4 further comprises the following specific steps: S41: placing an I-beam (4) at the bottom of the placement groove (2), and welding a flange of one side of the I-beam (4) to the low-carbon steel plate (3); S42: On the bottommost I-beam (4), a plurality of I-beams (4) are stacked in sequence from bottom to top, and adjacent I-beams (4) are spot-welded to form a rigid retaining structure (7); S43: Then, a low-carbon steel plate (3) is placed between the top of the rigid retaining structure (7) and the top of the placement groove (2) to separate them; S44: pouring concrete in the gap between the other side flange of the rigid retaining structure (7) and the placement groove (2) until the poured concrete seeps out, completing the construction of the first layer of the rigid retaining structure (7); after the poured concrete strength is formed, the next layer construction can be carried out.

6. The method for constructing underground continuous wall post-casting strips based on the cover-excavation reverse construction method according to claim 5 is characterized in that: The flanges on the other side of the rigid retaining structure (7) and the other side of the rigid retaining structure (7) and the low-carbon steel plate (3) on the top are all sealed and welded; and a through hole is left at the top for the grouting pipe to extend into.

7. The method for constructing underground continuous wall post-casting strips based on the cover-excavation reverse construction method according to claim 1 is characterized in that: In step S5, after the outer side surface of the next section of the post-cast strip (1) is excavated to place the groove (2), the soil in the gap at the bottom of the upper layer of the rigid retaining structure (7) needs to be removed until the concrete poured in the previous section is exposed; and a pulley hoisting device (6) is installed at the bottom of the upper layer of the rigid retaining structure (7).

8. The method for constructing underground continuous wall post-casting strips based on the cover-excavation reverse construction method according to claim 1 is characterized in that: Stiffening ribs are welded on the flanges on both sides of the I-beam (4) at the bottom.

9. The method for constructing underground continuous wall post-casting strips based on the cover-excavation reverse construction method according to claim 1, characterized in that: During the construction of several rigid retaining structures (7) from top to bottom, when encountering municipal pipeline facilities: Low carbon steel plates (3) need to be provided on both upper and lower sides of the pipeline, and both the low carbon steel plates (3) on the upper and lower sides are connected to the side walls of the post-casting strip (1); Subsequently, when constructing the rigid retaining structure (7), the rigid retaining structure (7) is disconnected at the location where it passes through the municipal pipeline, and the I-beam flanges on the upper and lower sides of the municipal pipeline are respectively welded to the low-carbon steel plates (3) on the upper and lower sides.

10. The method for constructing underground continuous wall post-casting strips based on the cover-excavation reverse construction method according to claim 1, characterized in that: In the step S5, when the construction process of a plurality of rigid retaining structures (7) is carried out in sequence from top to bottom, steel bars are simultaneously tied at the post-cast strip (1) of the completed rigid retaining structure (7).

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