Shell-abandoned recyclable underground continuous wall and construction method

Abstract

A shell-abandoned recyclable underground continuous wall, comprising a trench 1 and an enclosure structure, wherein the enclosure structure comprises multiple sets of enclosure units 2 arranged in the

Description

[0001 ] The present invention relates to the technical field of underground continuous walls, in particular to a shell-abandoned recyclable underground continuous wall and a construction method. BACKGROUND

[0002] With the continuous improvement of urbanization level, urban problems are increasingly prominent. The development and utilization of urban underground space has become one of the effective ways to solve urban diseases. At present, when urban underground space foundation pits are excavated, in view of the fact that ground settlement caused by precipitation endangers the safety of surrounding buildings (structures), and in order to ensure water-free operation in the foundation pits, enclosure structures for deep foundation pits are often cast-in-place reinforced concrete underground continuous walls, prefabricated underground continuous walls, or steel underground continuous walls.

[0003] In order to overcome the problem that steel bars or steel members in existing castin-place reinforced concrete underground continuous walls, prefabricated underground continuous walls, and steel underground continuous walls cannot be recycled after one-time investment, existing Chinese invention patent No. CN202311254332.8 discloses a construction method for a prefabricated underground continuous wall, belonging to the technical field of foundation pit construction, where the underground continuous wall includes a trench, a steel member arranged in the trench, a prefabricated concrete member arranged in the steel member, an inner mold bag filled in a gap between the steel member and the prefabricated concrete member, an outer mold bag filled in a gap between the steel member and a stratum, and slurry filled in the inner mold bag and the outer mold bag; adjacent steel members are spliced end to end to form a cavity for inserting the prefabricated concrete member; the inner mold bag includes a bag body I, a resistance wire I uniformly distributed on the bag body I, and a power cord I connected to the resistance wire I; the outer mold bag includes a bag body II, a resistor wire II uniformly distributed on the bag body II, and a power cord II connected to the resistor wire II; the hardened slurry can soften after being heated by the resistance wire I or the resistance wire II until liquefying. The construction method can solve the problems that the steel member of the prefabricated underground continuous wall is difficult to remove and the construction gap cannot be filled in a timely manner.

[0004] The above solution does not consider the difficulty of processing the steel member of the underground continuous wall, the impact on the width of the trench and the pouring thickness of a main structure, and the convenience of filling the construction gap during design, and in practice, still has the following problems:

[0005] Firstly, the connection form of the steel member is an open steel tube, which is more difficult to process than irregular structures; the open steel tube protrudes from the surface of the steel member, affecting the width of the trench and the thickness of concrete poured for the main structure; specifically, the open steel tube protrudes from the surface of the steel member, so in order to ensure the thickness of the open steel tube protruding from a steel reinforcement protective layer of the main structure, it is necessary to increase the thickness of the steel reinforcement protective layer of the main structure beyond the protruding position of the open steel tube, which also increases the contact area between the steel member and the main structure, increases the frictional resistance, and thus increases the pulling force and the difficulty of removing the steel member;

[0006] Secondly, the inner mold bag and the outer mold bag are filled with sulfur mortar, resulting in complex structure and process, poor operability, and low construction efficiency;

[0007] Thirdly, the cavity between the adj acent steel members is filled with a prefabricated concrete block, which reduces a lot of wet construction, but may still result in a gap between the prefabricated concrete block and the steel member, where the gap still needs to be backfilled multiple times when the mold bag is used, affecting the overall construction quality of the underground continuous wall. SUMMARY

[0008] The present invention provides a shell-abandoned recyclable underground continuous wall and a construction method, to solve the technical problems of high processing difficulty, increase in the thickness of a steel reinforcement protective layer of a main structure, increase in the contact area between a steel member and the main structure, and further increase in the difficulty of removing the steel member due to protruding at the connection of the steel member, as well as low construction efficiency caused by complex process and poor operability of using sulfur mortar in the prior art.

[0009] In order to achieve the above objective, the present invention adopts the following technical solutions:

[0010] The present invention provides a shell-abandoned recyclable underground continuous wall, including a trench and an enclosure structure, where the enclosure structure includes multiple sets of enclosure units arranged in the trench, and the multiple sets of enclosure units are connected along a length direction of the trench; a set of enclosure unit includes two interconnected steel members, a drag reduction shell, water stop bags, and cast-in-place concrete;

[0011] the entire steel member is an I-shaped plate, including a front transverse plate, a rear transverse plate, and a vertical plate connected between the front transverse plate and the rear transverse plate; the drag reduction shell is of a shell structure in the same shape as the steel member, and is sleeved on a surface of the steel member as an outer shell of the steel member;

[0012] a left end of the front transverse plate is provided with a first F-shaped plate and a right end thereof is provided with a first U-shaped plate, a left end of the rear transverse plate is provided with a second U-shaped plate and a right end thereof is provided with a second F-shaped plate, where the first F-shaped plate and the second F-shaped plate are symmetrical about a center point of the vertical plate, and the first U-shaped plate and the second U-shaped plate are also symmetrical about the center point of the vertical plate; and

[0013] in the two interconnected steel members, the first U-shaped plate of the left steel member is clamped and fixed with the first F-shaped plate of the right steel member, and the second F-shaped plate of the left steel member is clamped and fixed with the second U-shaped plate of the right steel member; the water stop bags are provided at joints between the left steel member and the right steel member; and a closed space enclosed by the left steel member and the right steel frame is filled with the cast-in-place concrete.

[0014] Preferably, the first F-shaped plate is a strip plate, and is arranged throughout the length in a height direction at the left end of the front transverse plate; the first F-shaped plate includes a main plate, and a convex rib is provided on each of an outer edge and a middle portion of an inner side of the main plate, so that the cross-section of the first F-shaped plate is "F"-shaped; an inner edge of the main plate of the first F-shaped plate is fixedly connected to the left end of the front transverse plate, so that the back of the main plate is flush with the inner side of the front transverse plate.

[0015] Preferably, the first U-shaped plate is arranged throughout the length in the height direction at the right end of the front transverse plate; the first U-shaped plate includes a bottom plate, a long side plate, and a short side plate; an opening of the first U-shaped plate faces the front transverse plate, and the side of the long side plate away from the bottom plate is fixedly connected to an inner side of an edge of the front transverse plate; the bottom plate is parallel to the front transverse plate, and the end of the bottom plate away from the long side plate exceeds the edge of the front transverse plate; the width of the short side plate is less than that of the long side plate, one side of the short side plate is fixedly connected to the bottom plate and the other side is spaced apart from the front transverse plate; and the first U-shaped plate and the front transverse plate enclose a semi-closed space for inserting the first F-shaped plate of the adjacent steel member.

[0016] Preferably, the water stop bag is a hollow bag band and is arranged between the convex ribs of the first F-shaped plate or the second F-shaped plate to stop water.

[0017] Preferably, strata are on both sides of the trench, and a filling material is provided between the steel members and the strata.

[0018] Preferably, the filling material is fluid solidified soil or quick setting slurry.

[0019] Preferably, a top surface of the steel member is higher than that of the drag reduction shell, and the top surface of the steel member is provided with a lifting hole or a lifting ring for early lifting and easy removal in the later stage.

[0020] Preferably, the drag reduction shell is made of plastic, and a drag reduction layer is provided between the drag reduction shell and the steel member to reduce friction between the steel member and the drag reduction shell.

[0021] Preferably, the drag reduction layer is made of powder or oil with low friction coefficient, such as polytetrafluoroethylene or molybdenum disulfide.

[0022] The present invention further provides a construction method for the aforementioned shell-abandoned recyclable underground continuous wall, including the following steps:

[0023] step 1: carrying out surveying and setting-out on a construction site to determine a specific position of the enclosure structure;

[0024] step 2: excavating the trench for a steel guide wall and constructing the guide wall;

[0025] step 3: excavating the trench at the enclosure structure through a trenching device according to construction drawing design under the condition of wall protection by slurry, and cleaning the bottom;

[0026] step 4: mounting the drag reduction shell to the steel member, mounting the water stop bags to the first F-shaped plate and the second F-shaped plate, lifting the steel member, the drag reduction shell and the water stop bags into the trench, filling the water stop bags with water to increase pressure, and discharging the slurry inside the trench at the enclosure structure;

[0027] step 5: connecting and fixing the steel member to the steel guide wall;

[0028] step 6: pouring concrete into the cavity formed by the adjacent steel members, and at the same time, discharging some of the slurry inside the trench at the enclosure structure;

[0029] step 7: repeating steps 4 to 6 to complete the construction of the steel members and the concrete in the first enclosure unit;

[0030] step 8: injecting the filling material into gaps between the steel members and the strata to complete the construction of the entire first enclosure unit;

[0031] step 9: repeating steps 1 to 8 until the construction of the entire second enclosure unit is completed;

[0032] step 10: repeating step 9 until the construction of the enclosure structure of an entire foundation pit is completed;

[0033] step 11: removing the steel members from the drag reduction shell after the construction of a main structure is completed and the strength thereof reaches a design strength; and

[0034] step 12: injecting the filling material in real time into removal positions, namely, the inside of the drag reduction shell while removing the steel members, and extruding and filling construction gaps after the steel members are removed, thereby completing backfilling construction of the construction gaps of the underground continuous wall.

[0035] Beneficial effects of the present invention are embodied as follows:

[0036] 1) The present invention provides a shell-abandoned recyclable underground continuous wall and a construction method, where an F-shaped plate and a U-shaped plate are provided at two ends of a front transverse plate or a rear transverse plate, achieving low processing difficulty; adjacent steel members are connected by inserting fit between the F-shaped plates and the U-shaped plates, achieving skillful structural settings, good integrity, good structural stability, and convenient construction; the F-shaped plate and the U-shaped plate do not exceed the outer side of the front or rear transverse plate, which does not affect the width of a trench and the thickness of concrete poured for a main structure;

[0037] 2) The present invention provides a shell-abandoned recyclable underground continuous wall and a construction method, where the outer surface of the steel member is covered with a drag reduction shell, which serves as a mold; after the strength of the main structure reaches the standard, due to the low friction between the steel member and the drag reduction shell, the steel member can be removed through a crane, achieving reuse of the steel member, solving the problem of difficult removal of the steel member, and achieving strong economic efficiency and circulation;

[0038] 3) The present invention provides a shell-abandoned recyclable underground continuous wall and construction method, where after the steel member is removed, fluid solidified soil is injected and extruded to fill construction gaps in the drag reduction shell, thereby improving the convenience of backfilling the construction gaps and solving the technical problem of complex operation of filling the construction gaps.

[0039] Other features and advantages of the present invention will be elaborated in the following description and partially become apparent from the description, or can be learned by implementing the present invention. The main objectives and other advantages of the present invention can be achieved and obtained through the solutions specified in the description. BRIEF DESCRIPTION OF DRAWINGS

[0040] Fig. lisa schematic plan view of an enclosure structure of the present invention in a trench.

[0041] Fig. 2 is a plan view of a steel member of the present invention.

[0042] Fig. 3 is a plan view of a drag reduction shell of the present invention.

[0043] Fig. 4 is a schematic plan view of the enclosure structure of the present invention after steel members are removed.

[0044] Reference numerals: 1 - trench, 2 - enclosure unit, 21 - steel member, 211 - front transverse plate, 212 - rear transverse plate, 213 - vertical plate, 214 - first F-shaped plate, 2141 -main plate, 2142 - convex rib; 215 - first U-shaped plate, 2151 - bottom plate, 2152 - long side plate, 2153 - short side plate; 216 - second F-shaped plate, 217 - second U-shaped plate; 22 - drag reduction shell, 23 - water stop bag, 24 - cast-in-place concrete, 3 - stratum, 4 - filling material. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0045] The technical solutions of the present invention will be described in detail below through embodiments. The following embodiments are merely exemplary, can only be used to explain and illustrate the technical solutions of the present invention, and cannot be interpreted as limiting the technical solutions of the present invention.

[0046] This embodiment takes a foundation pit construction plan of a certain building project as an example. In the prior art, the connection of a steel member 21 is an open steel tube, resulting in the problems of high processing difficulty, increase in the thickness of a concrete protective layer, and the like. On this basis, design optimization is carried out by alternately arranging a U-shaped plate and an F-shaped plate at both ends and on each side of the steel member 21, ensuring that the F-shaped plate is close to the steel member 21, with clever structural settings, good overall integrity, and good structural stability. In the prior art, sulfur mortar is softened by heating to reduce the extrusion force and friction force between a prefabricated concrete member and the steel member 21, achieving easy removal of the steel member 21. However, this scheme has poor operability and is not practical in actual construction. Therefore, this embodiment abandons this scheme, but achieves later removal of the steel member 21 by arranging a drag reduction shell 22 on the surface of the steel member 21, thereby greatly reducing the difficulty of removing the steel member 21, and improving the removing construction efficiency and recovery rate of the steel member 21. Meanwhile, after the steel member 21 is removed, the construction gap is filled by grouting and squeezing on both sides, thereby improving the convenience of backfilling the construction gap and achieving strong practicality and operability. In practical engineering applications, this embodiment solves the problems that the existing steel member 21 is difficult to process and the width of a trench 1 and the thickness of concrete poured for a main structure are affected, achieves reasonable structural settings, reduces engineering costs, and achieves strong economic efficiency and application prospects.

[0047] With reference to Fig. 1, the present invention provides a shell-abandoned recyclable underground continuous wall, including a trench 1 and an enclosure structure, where the enclosure structure includes multiple sets of enclosure units 2 arranged in the trench 1, and the multiple sets of enclosure units 2 are connected along a length direction of the trench 1; a set of enclosure unit 2 includes two interconnected steel members 21, a drag reduction shell 22, water stop bags 23, and cast-in-place concrete 24; strata 3 are on both sides of the trench 1, a filling material 4 is provided between the steel members 21 and the strata 3, and the filling material 4 is fluid solidified soil or quick setting slurry.

[0048] With reference to Figs. 2 and 3, the entire steel member 21 is an I-shaped plate, including a front transverse plate 211, a rear transverse plate 212, and a vertical plate 213 connected between the front transverse plate 211 and the rear transverse plate 212; the drag reduction shell 22 is of a shell structure in the same shape as the steel member 21, and is sleeved on a surface of the steel member 21 as an outer shell of the steel member 21; the drag reduction shell 22 is made of plastic, and a drag reduction layer is provided between the drag reduction shell 22 and the steel member 21 to reduce friction between the steel member 21 and the drag reduction shell 22, where the drag reduction layer is made of powder or oil with low friction coefficient, such as polytetrafluoroethylene or molybdenum disulfide; a top surface of the steel member 21 is higher than that of the drag reduction shell 22, and the top surface of the steel member 21 is provided with a lifting hole or a lifting ring for early lifting and easy removal in the later stage.

[0049] A left end of the front transverse plate 211 is provided with a first F-shaped plate 214 and a right end thereof is provided with a first U-shaped plate 215, a left end of the rear transverse plate 212 is provided with a second U-shaped plate 217 and a right end thereof is provided with a second F-shaped plate 216, where the first F-shaped plate 214 and the second F-shaped plate 216 are symmetrical about a center point of the vertical plate 213, and the first U-shaped plate 215 and the second U-shaped plate 217 are also symmetrical about the center point of the vertical plate 213; the first F-shaped plate 214 is a strip plate, and is arranged throughout the length in a height direction at the left end of the front transverse plate 211; the first F-shaped plate 214 includes a main plate 2141, and a convex rib 2142 is provided on each of an outer edge and a middle portion of an inner side of the main plate 2141, so that the cross-section of the first F-shaped plate 214 is "F"-shaped; an inner edge of the main plate 2141 of the first F-shaped plate 214 is fixedly connected to the left end of the front transverse plate 211, so that the back of the main plate 2141 is flush with the inner side of the front transverse plate 211. The first U-shaped plate 215 is arranged throughout the length in the height direction at the right end of the front transverse plate 211; the first U-shaped plate 215 includes a bottom plate 2151, a long side plate 2152, and a short side plate 2153; an opening of the first U-shaped plate 215 faces the front transverse plate 211, and the side of the long side plate 2152 away from the bottom plate 2151 is fixedly connected to an inner side of an edge of the front transverse plate 211; the bottom plate 2151 is parallel to the front transverse plate 211, and the end of the bottom plate 2151 away from the long side plate 2152 exceeds the edge of the front transverse plate 211; the width of the short side plate 2153 is less than that of the long side plate 2152, one side of the short side plate 2153 is fixedly connected to the bottom plate 2151 and the other side is spaced apart from the front transverse plate 211; and the first U-shaped plate 215 and the front transverse plate 211 enclose a semi-closed space for inserting the first F-shaped plate 214 of the adjacent steel member 21.

[0050] In the two interconnected steel members 21, the first U-shaped plate 215 of the left steel member 21 is clamped and fixed with the first F-shaped plate 214 of the right steel member 21, and the second F-shaped plate 216 of the left steel member 21 is clamped and fixed with the second U-shaped plate 217 of the right steel member 21; the water stop bags 23 are provided at joints between the left steel member 21 and the right steel member 21, the water stop bag 23 is a hollow bag band and is arranged between the convex ribs 2142 of the first F-shaped plate 214 or the second F-shaped plate 216 to stop water; and the closed space enclosed by the left steel member 21 and the right steel frame is filled with the cast-in-place concrete 24.

[0051] The present invention further provides a construction method for the aforementioned shell-abandoned recyclable underground continuous wall, including the following steps:

[0052] step 1: carrying out surveying and setting-out on a construction site to determine a specific position of the enclosure structure;

[0053] step 2: excavating the trench 1 for a steel guide wall and constructing the guide wall;

[0054] step 3: excavating the trench 1 at the enclosure structure through a trenching device according to construction drawing design under the condition of wall protection by slurry, and cleaning the bottom;

[0055] step 4: mounting the drag reduction shell 22 to the steel member 21, mounting the water stop bags 23 to the first F-shaped plate 214 and the second F-shaped plate 216, lifting the steel member 21, the drag reduction shell 22 and the water stop bags 23 into the trench 1, filling the water stop bags 23 with water to increase pressure, and discharging the slurry inside the trench 1 at the enclosure structure;

[0056] step 5: connecting and fixing the steel member 21 to the steel guide wall;

[0057] step 6: pouring concrete into the cavity formed by the adjacent steel members 21, and at the same time, discharging some of the slurry inside the trench 1 at the enclosure structure;

[0058] step 7: repeating steps 4 to 6 to complete the construction of the steel members 21 and the concrete in the first enclosure unit 2;

[0059] step 8: injecting the filling material 4 into gaps between the steel members 21 and the strata 3 to complete the construction of the entire first enclosure unit 2;

[0060] step 9: repeating steps 1 to 8 until the construction of the entire second enclosure unit 2 is completed;

[0061] step 10: repeating step 9 until the construction of the enclosure structure of an entire foundation pit is completed;

[0062] step 11: removing the steel members 21 from the drag reduction shell 22 after the construction of a main structure is completed and the strength thereof reaches a design strength; and

[0063] step 12: with reference to Fig. 4, injecting the filling material 4 in real time into removal positions, namely, the inside of the drag reduction shell 22 while removing the steel members 21, and extruding and filling construction gaps after the steel members 21 are removed, thereby completing backfilling construction of the construction gaps of the underground continuous wall.

[0064] Described above are merely preferred specific embodiments of the present invention, but the scope of protection of the present invention is not limited thereto. Variations or substitutions conceived by any skilled person familiar with the technical field within the technical scope disclosed in the present invention shall fall within the scope of protection of the present invention.

Claims

1. A shell-abandoned recyclable underground continuous wall, comprising a trench (1) and an enclosure structure, wherein the enclosure structure comprises multiple sets of enclosure units (2) arranged in the trench (1), and the multiple sets of enclosure units (2) are connected along a length direction of the trench (1); a set of enclosure unit (2) comprises two interconnected steel members (21), a drag reduction shell (22), water stop bags (23), and cast-in-place concrete (24);the entire steel member (21) is an I-shaped plate, comprising a front transverse plate (211), a rear transverse plate (212), and a vertical plate (213) connected between the front transverse plate (211) and the rear transverse plate (212); the drag reduction shell (22) is of a shell structure in the same shape as the steel member (21), and is sleeved on a surface of the steel member (21) as an outer shell of the steel member (21);a left end of the front transverse plate (211) is provided with a first F-shaped plate (214) and a right end thereof is provided with a first U-shaped plate (215), a left end of the rear transverse plate (212) is provided with a second U-shaped plate (217) and a right end thereof is provided with a second F-shaped plate (216), wherein the first F-shaped plate (214) and the second F-shaped plate (216) are symmetrical about a center point of the vertical plate (213), and the first U-shaped plate (215) and the second U-shaped plate (217) are also symmetrical about the center point of the vertical plate (213); andin the two interconnected steel members (21), the first U-shaped plate (215) of the left steel member (21) is clamped and fixed with the first F-shaped plate (214) of the right steel member (21), and the second F-shaped plate (216) of the left steel member (21) is clamped and fixed with the second U-shaped plate (217) of the right steel member (21); the water stop bags (23) are provided at joints between the left steel member (21) and the right steel member (21); and a closed space enclosed by the left steel member (21) and the right steel frame is filled with the cast-in-place concrete (24).

2. The shell-abandoned recyclable underground continuous wall according to claim 1, wherein the first F-shaped plate (214) is a strip plate, and is arranged throughout the length in a height direction at the left end of the front transverse plate (211); the first F-shaped plate (214) comprises a main plate (2141), and a convex rib (2142) is provided on each of an outer edge and a middle portion of an inner side of the main plate (2141), so that the cross-section of the first F-11shaped plate (214) is "F"-shaped; an inner edge of the main plate (2141) of the first F-shaped plate (214) is fixedly connected to the left end of the front transverse plate (211), so that the back of the main plate (2141) is flush with the inner side of the front transverse plate (211).

3. The shell-abandoned recyclable underground continuous wall according to claim 2, wherein the first U-shaped plate (215) is arranged throughout the length in the height direction at the right end of the front transverse plate (211); the first U-shaped plate (215) comprises a bottom plate (2151), a long side plate (2152), and a short side plate (2153); an opening of the first U-shaped plate (215) faces the front transverse plate (211), and the side of the long side plate (2152) away from the bottom plate (2151) is fixedly connected to an inner side of an edge of the front transverse plate (211); the bottom plate (2151) is parallel to the front transverse plate (211), and the end of the bottom plate (2151) away from the long side plate (2152) exceeds the edge of the front transverse plate (211); the width of the short side plate (2153) is less than that of the long side plate (2152), one side of the short side plate (2153) is fixedly connected to the bottom plate (2151) and the other side is spaced apart from the front transverse plate (211); and the first U-shaped plate (215) and the front transverse plate (211) enclose a semi-closed space for inserting the first F-shaped plate (214) of the adjacent steel member (21).

4. The shell-abandoned recyclable underground continuous wall according to claim 2, wherein the water stop bag (23) is a hollow bag band and is arranged between the convex ribs (2142) of the first F-shaped plate (214) or the second F-shaped plate (216) to stop water.

5. The shell-abandoned recyclable underground continuous wall according to claim 1, wherein strata (3) are on both sides of the trench (1), and a filling material (4) is provided between the steel members (21) and the strata (3).

6. The shell-abandoned recyclable underground continuous wall according to claim 5, wherein the filling material (4) is fluid solidified soil or quick setting slurry.

7. The shell-abandoned recyclable underground continuous wall according to claim 4, wherein a top surface of the steel member (21) is higher than that of the drag reduction shell (22),and the top surface of the steel member (21) is provided with a lifting hole or a lifting ring for early lifting and easy removal in the later stage.

8. The shell-abandoned recyclable underground continuous wall according to claim 1, wherein the drag reduction shell (22) is made of plastic, and a drag reduction layer is provided between the drag reduction shell (22) and the steel member (21) to reduce friction between the steel member (21) and the drag reduction shell (22).

9. The shell-abandoned recyclable underground continuous wall according to claim 8, wherein the drag reduction layer is made of polytetrafluoroethylene or molybdenum disulfide.

10. A construction method for the shell-abandoned recyclable underground continuous wall according to any one of claims 1 to 9, comprising the following steps:step 1: carrying out surveying and setting-out on a construction site to determine a specific position of the enclosure structure;step 2: excavating the trench (1) for a steel guide wall and constructing the guide wall;step 3: excavating the trench (1) at the enclosure structure through a trenching device according to construction drawing design under the condition of wall protection by slurry, and cleaning the bottom;step 4: mounting the drag reduction shell (22) to the steel member (21), mounting the water stop bags (23) to the first F-shaped plate (214) and the second F-shaped plate (216), lifting the steel member (21), the drag reduction shell (22) and the water stop bags (23) into the trench (1), filling the water stop bags (23) with water to increase pressure, and discharging the slurry inside the trench (1) at the enclosure structure;step 5: connecting and fixing the steel member (21) to the steel guide wall;step 6: pouring concrete into the cavity formed by the adjacent steel members (21), and at the same time, discharging some of the slurry inside the trench (1) at the enclosure structure;step 7: repeating steps 4 to 6 to complete the construction of the steel members (21) and the concrete in the first enclosure unit (2);step 8: injecting the filling material (4) into gaps between the steel members (21) and the strata (3) to complete the construction of the entire first enclosure unit (2);step 9: repeating steps 1 to 8 until the construction of the entire second enclosure unit (2) is completed;step 10: repeating step 9 until the construction of the enclosure structure of an entire foundation pit is completed;step 11: removing the steel members (21) from the drag reduction shell (22) after the construction of a main structure is completed and the strength thereof reaches a design strength; andstep 12: injecting the filling material (4) in real time into removal positions, namely, the inside of the drag reduction shell (22) while removing the steel members (21), and extruding and filling construction gaps after the steel members (21) are removed, thereby completing backfilling construction of the construction gaps of the underground continuous wall.AMENDMENTS TO THE CLAIMS HAVE BEEN FILED AS FOLLOWS17 03 26WHAT IS CLAIMED IS:

1. A shell-abandoned recyclable underground continuous wall, comprising a trench (1) and an enclosure structure, wherein the enclosure structure comprises multiple sets of enclosure units (2) arranged in the trench (1), and the multiple sets of enclosure units (2) are connected along a length direction of the trench (1); a set of enclosure unit (2) comprises two interconnected steel members (21), a drag reduction shell (22), water stop bags (23), and cast-in-place concrete (24);the entire steel member (21) is an I-shaped plate, comprising a front transverse plate (211), a rear transverse plate (212), and a vertical plate (213) connected between the front transverse plate (211) and the rear transverse plate (212); the drag reduction shell (22) is of a shell structure in the same shape as the steel member (21), and is sleeved on a surface of the steel member (21) as an outer shell of the steel member (21);a left end of the front transverse plate (211) is provided with a first F-shaped plate (214) and a right end thereof is provided with a first U-shaped plate (215), a left end of the rear transverse plate (212) is provided with a second U-shaped plate (217) and a right end thereof is provided with a second F-shaped plate (216), wherein the first F-shaped plate (214) and the second F-shaped plate (216) are rotational symmetry,and the first U-shaped plate (215) and the second U-shaped plate (217) are also rotational symmetry andin the two interconnected steel members (21), the first U-shaped plate (215) of the left steel member (21) is clamped and fixed with the first F-shaped plate (214) of the right steel member (21), and the second F-shaped plate (216) of the left steel member (21) is clamped and fixed with the second U-shaped plate (217) of the right steel member (21); the water stop bags (23) are provided at joints between the left steel member (21) and the right steel member (21); and a closed space enclosed by the left steel member (21) and the right steel frame is filled with the cast-in-place concrete (24).

2. The shell-abandoned recyclable underground continuous wall according to claim 1, wherein the first F-shaped plate (214) is a strip plate, and is arranged throughout the length in a height direction at the left end of the front transverse plate (211); the first F-shaped plate (214)17 03 26comprises a main plate (2141), and a convex rib (2142) is provided on each of an outer edge and a middle portion of an inner side of the main plate (2141), so that the cross-section of the first F-shaped plate (214) is "F"-shaped; an inner edge of the main plate (2141) of the first F-shaped plate (214) is fixedly connected to the left end of the front transverse plate (211), so that the back of the main plate (2141) is flush with the inner side of the front transverse plate (211).

3. The shell-abandoned recyclable underground continuous wall according to claim 2, wherein the first U-shaped plate (215) is arranged throughout the length in the height direction at the right end of the front transverse plate (211); the first U-shaped plate (215) comprises a bottom plate (2151), a long side plate (2152), and a short side plate (2153); an opening of the first U-shaped plate (215) faces the front transverse plate (211), and the side of the long side plate (2152) away from the bottom plate (2151) is fixedly connected to an inner side of an edge of the front transverse plate (211); the bottom plate (2151) is parallel to the front transverse plate (211), and the end of the bottom plate (2151) away from the long side plate (2152) exceeds the edge of the front transverse plate (211); the width of the short side plate (2153) is less than that of the long side plate (2152), one side of the short side plate (2153) is fixedly connected to the bottom plate (2151) and the other side is spaced apart from the front transverse plate (211); and the first U-shaped plate (215) and the front transverse plate (211) enclose a semi-closed space for inserting the first F-shaped plate (214) of the adjacent steel member (21).

4. The shell-abandoned recyclable underground continuous wall according to claim 2, wherein the water stop bag (23) is a hollow bag band and is arranged between the convex ribs (2142) of the first F-shaped plate (214) or the second F-shaped plate (216) to stop water.

5. The shell-abandoned recyclable underground continuous wall according to claim 1, wherein strata (3) are on both sides of the trench (1), and a filling material (4) is provided between the steel members (21) and the strata (3).

6. The shell-abandoned recyclable underground continuous wall according to claim 5,wherein the filling material (4) is fluid solidified soil or quick setting slurry.17 03 267. The shell-abandoned recyclable underground continuous wall according to claim 4, wherein a top surface of the steel member (21) is higher than that of the drag reduction shell (22), and the top surface of the steel member (21) is provided with a lifting hole or a lifting ring for early lifting and easy removal in the later stage.

8. The shell-abandoned recyclable underground continuous wall according to claim 1, wherein the drag reduction shell (22) is made of plastic, and a drag reduction layer is provided between the drag reduction shell (22) and the steel member (21) to reduce friction between the steel member (21) and the drag reduction shell (22).

9. The shell-abandoned recyclable underground continuous wall according to claim 8, wherein the drag reduction layer is made of polytetrafluoroethylene or molybdenum disulfide.

10. A construction method for the shell-abandoned recyclable underground continuous wall according to any one of claims 1 to 9, comprising the following steps:step 1: carrying out surveying and setting-out on a construction site to determine a specific position of the enclosure structure;step 2: excavating the trench (1) for a steel guide wall and constructing the guide wall;step 3: excavating the trench (1) at the enclosure structure through a trenching device according to construction drawing design under the condition of wall protection by slurry, and cleaning the bottom;step 4: mounting the drag reduction shell (22) to the steel member (21), mounting the water stop bags (23) to the first F-shaped plate (214) and the second F-shaped plate (216), lifting the steel member (21), the drag reduction shell (22) and the water stop bags (23) into the trench (1), filling the water stop bags (23) with water to increase pressure, and discharging the slurry inside the trench (1) at the enclosure structure;step 5: connecting and fixing the steel member (21) to the steel guide wall;step 6: pouring concrete into the cavity formed by the adjacent steel members (21), and at17 03 26the same time, discharging some of the slurry inside the trench (1) at the enclosure structure;step 7: repeating steps 4 to 6 to complete the construction of the steel members (21) and the concrete in the first enclosure unit (2);step 8: injecting the filling material (4) into gaps between the steel members (21) and the strata (3) to complete the construction of the entire first enclosure unit (2);step 9: repeating steps 1 to 8 until the construction of the entire second enclosure unit (2) is completed;step 10: repeating step 9 until the construction of the enclosure structure of an entire foundation pit is completed;step 11: removing the steel members (21) from the drag reduction shell (22) after the construction of a main structure is completed and the strength thereof reaches a design strength; andstep 12: injecting the filling material (4) in real time into removal positions, namely, the inside of the drag reduction shell (22) while removing the steel members (21), and extruding and filling construction gaps after the steel members (21) are removed, thereby completing backfilling construction of the construction gaps of the underground continuous wall.A

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