A prefabricated grid-shaped underground continuous wall without internal support and its construction process

Abstract

The present invention belongs to the field of underground foundation pit engineering retaining structures, and specifically relates to a prefabricated grid-shaped underground continuous wall without internal support. The grid-shaped underground continuous wall is assembled from two end wall segment structures and a plurality of groups of middle wall segment structures. The end wall segment structure is a cap-shaped wall segment structure or an L-shaped wall segment structure, and the middle wall segment structure is an I-shaped wall segment structure or a displaced T-shaped wall segment structure. The construction process of the present invention includes guide wall construction, grooving, hoisting prefabricated underground continuous walls, vertical underground continuous wall splicing, horizontal underground continuous wall connection, and hollow section backfilling process. The present invention is economical and environmentally friendly, can improve the construction speed, and because each continuous wall segment adopts an asymmetric joint, it can prevent the wall from shearing along the unified joint. The present invention can also achieve the stability of the foundation pit without internal support structure.

Description

Technical Field

[0001] The invention belongs to the field of underground foundation pit engineering retaining structures, and specifically relates to an assembled prefabricated lattice underground continuous wall without internal support and a construction process thereof. Background Art

[0002] At present, the grid-shaped underground continuous wall structure is mainly composed of inner longitudinal walls, outer longitudinal walls and transverse diaphragms. The transverse diaphragms connect the inner and outer longitudinal walls to form a grid structure and the original soil inside it to form a semi-gravity structure. When used as the retaining structure of the foundation pit, it can bear the water and soil pressure outside the pit during the foundation pit construction process by itself without the need for an internal support structure.

[0003] At present, the grid-shaped underground continuous wall is mainly realized by cast-in-place technology, and each wall section is spliced ​​in a straight line. However, due to the problems of untimely support after the excavation of the trench wall in cast-in-place construction, long construction period of cast-in-place technology, rough wall surface of cast-in-place underground continuous wall, limited construction site and corresponding inner and outer wall sections, the existing grid structure is prone to trench wall collapse and mud exposure in poor strata; the construction period is long in foundation pit construction projects in densely built areas, which will bring inconvenience to traffic operations; due to the rough wall surface, the foundation pit construction as the main structure needs secondary treatment to increase construction costs; due to the large structure, it is currently mainly used in large-scale port projects and due to the corresponding inner and outer wall sections, it is easy to break as a whole from the section during the force process, causing safety hazards. Therefore, there are major deficiencies in the construction safety, speed, economy and practicality of the foundation pit construction using cast-in-place grid-shaped underground continuous wall.

[0004] The existing prefabricated underground continuous wall structure adopts a straight-line structure, which needs to work together with the internal support structure to stabilize the foundation pit during construction. For large-scale underground space projects, due to the large structure, internal support cannot be provided, and the straight-line underground continuous wall cannot meet the stability of the foundation pit, which will cause the foundation pit wall to collapse and serious safety accidents. Summary of the invention

[0005] The purpose of the present invention is to provide a prefabricated grid-shaped underground continuous wall without internal support and its construction process, so as to overcome the shortcomings of the existing grid-shaped underground continuous wall that the inner and outer wall sections correspond to each other and are easily disconnected as a whole at the section during the stress process; solve the problem of foundation pit engineering in underground space structures where internal support structures cannot be made; solve the problems of trench wall collapse and long construction period due to untimely support in cast-in-place construction.

[0006] To achieve the above purpose, the technical solution adopted by the present invention is:

[0007] A prefabricated grid-shaped underground continuous wall without internal support, wherein the grid-shaped underground continuous wall is assembled from two end wall segment structures and a plurality of groups of intermediate wall segment structures, wherein the end wall segment structure is a cap-shaped wall segment structure or an L-shaped wall segment structure, and the intermediate wall segment structure is an I-shaped wall segment structure or a staggered T-shaped wall segment structure, wherein the L-shaped wall segment structure includes a first L-shaped wall segment structure and a second L-shaped wall segment structure, wherein one end wall segment structure is assembled from a first L-shaped wall segment structure and a second L-shaped wall segment structure, wherein the T-shaped wall segment structure includes a first staggered T-shaped wall segment structure and a second staggered T-shaped wall segment structure, and wherein the first staggered T-shaped wall segment structure and the second staggered T-shaped wall segment structure are assembled into a group of intermediate wall segment structures.

[0008] The I-shaped wall section structure includes a first longitudinal wall section, a second longitudinal wall section and a first transverse partition wall section. The first transverse partition wall section is placed between the first longitudinal wall section and the second longitudinal wall section. The first longitudinal wall section, the second longitudinal wall section and the first transverse partition wall section are hollow inside and form an asymmetrical I-shape.

[0009] The cover-type wall section structure includes a third longitudinal wall section, a fourth longitudinal wall section and a second transverse partition wall section. The second transverse partition wall section is connected to one side of the third longitudinal wall section and the fourth longitudinal wall section to prefabricate the cover-type wall section structure. The third longitudinal wall section is longer than the fourth longitudinal wall section.

[0010] The first offset T-shaped wall segment structure is composed of the fifth longitudinal wall section and the third transverse partition wall section, the third transverse partition wall section is connected to a portion of the fifth longitudinal wall section that is off to one side of the center, the third transverse partition wall section and the fifth longitudinal wall section are hollow hole structures inside, a cross steel plate is preset at the end of the third transverse partition wall section, a cross steel plate is preset at the end of the fifth longitudinal wall section that is vertically farther from the center line of the third transverse partition wall section, and a cross steel plate groove is reserved at the end of the fifth longitudinal wall section that is vertically farther from the center line of the third transverse partition wall section; The second offset T-shaped wall section structure is composed of the sixth longitudinal wall section and the fourth transverse partition wall section. The fourth transverse partition wall section is connected to the part on the other side of the center of the sixth longitudinal wall section. The fourth transverse partition wall section and the sixth longitudinal wall section have hollow hole structures inside. A cross steel plate groove is reserved at the end of the fourth transverse partition wall section. A cross steel plate groove is reserved at the end of the sixth longitudinal wall section that has a larger vertical distance from the center line of the fourth transverse partition wall section. A cross steel plate is preset at the end of the sixth longitudinal wall section that has a smaller vertical distance from the center line of the fourth transverse partition wall section.

[0011] The first L-shaped wall section structure is prefabricated into an L-shape by the seventh longitudinal wall section and the fifth transverse partition wall section, a cross steel plate is preset at the end of the seventh longitudinal wall section, and a cross steel plate groove is reserved at the end of the fifth transverse partition wall section; the second L-shaped wall section structure is prefabricated into an L-shape by the eighth longitudinal wall section and the sixth transverse partition wall section, the seventh longitudinal wall section is shorter than the eighth longitudinal wall section, and cross steel plates are preset at the ends of the eighth longitudinal wall section and the sixth transverse partition wall section.

[0012] A construction process of a prefabricated grid underground continuous wall without internal support, characterized in that it includes guide wall construction, troughing, hoisting prefabricated underground continuous wall, vertical underground continuous wall splicing, horizontal underground continuous wall connection, and cross-section backfilling process;

[0013] The guide wall construction process is as follows: the guide wall cross section adopts an inverted L-shape, two times of mold casting and curing, and the guide wall is deepened during the construction process, and the depth of the guide wall is greater than 2m;

[0014] The trenching process: when trenching, use mud with high viscosity, low water loss and tough mud skin surface; during the trenching process, test the mud index and observe the trench. When the mud viscosity reaches 40-50s and the specific gravity is less than 1.25g / cm 3 When the water loss rate is less than 30mg / 30min and the pH value is between 8 and 10, the mud in the tank meets the standard. If the index is insufficient, admixtures should be added in time to meet the mud performance index;

[0015] The process of hoisting the prefabricated underground continuous wall is as follows: before the prefabricated underground continuous wall is hoisted, a force transmission pad is pre-pasted on the annular surface and the longitudinal surface of the prefabricated underground continuous wall. The length of each section of the prefabricated underground continuous wall is less than 10m. During prefabrication, hoisting positioning holes are reserved on both sides of the wall section of the underground continuous wall. The positioning holes are used to rotate the screws on the assembly fixing frame and push them into the fixing holes so that they are temporarily placed on the guide groove, which is convenient for the splicing of the upper and lower prefabricated underground continuous walls.

[0016] The splicing process of the vertical underground continuous wall is: using steel plate joints for connection, that is, the connection end plates embedded at the end faces of the upper and lower prefabricated wall sections are connected by groove welding and combined with steel bar anchoring. When the wall sections are manufactured in the factory, a certain number of dowel bars are reserved at the bottom of the upper prefabricated wall section, and steel bar holes corresponding to the dowel bars of the upper section are reserved at the top of the lower wall section. During on-site docking construction, the cementing material is first poured into the reserved holes of the lower wall section, and then the upper wall section is lowered to insert the steel bars into the reserved holes to form an anchoring connection, and then the connection end plates are connected by groove welding.

[0017] The horizontal underground continuous wall connection process is: using a cross steel sheet pile joint connection, pre-buried half of the cross steel sheet pile on one side of the wall section during the prefabrication process, and reserved a groove matching the cross steel sheet pile on the other side, and butted the side with the cross steel sheet pile with the side with the groove during construction, and applied water-expandable waterproofing glue on the groove part before the joint connection, and after the hoisting connection, the expanding waterproofing glue expands under the action of water to fill the entire gap and tightly connect the two wall sections;

[0018] The hollow section backfilling process is: backfilling the hollow section of the structure by concrete grouting or soil.

[0019] Beneficial effects:

[0020] (1) The present invention proposes an assembled grid-shaped underground continuous wall, which is economical and environmentally friendly, can increase the construction speed, and because each continuous wall groove section adopts an asymmetric joint, it can prevent shear damage of the wall along the uniform joint, thereby enhancing the stability of the wall;

[0021] (2) The underground continuous wall of the present invention is prefabricated, and the wall surface is smooth, the surrounding foundation pit is stable, and the factory industrial standard production can be achieved, which can improve the construction speed;

[0022] (3) The present invention forms a semi-gravity structure through a special lattice structure and the original soil inside it, and relies on itself to bear the water and soil pressure outside the pit during the foundation pit construction process, thereby achieving the stability of the foundation pit without an internal support structure;

[0023] (4) After the construction of the present invention is completed, it can also be directly used as the outer wall of the underground structure and bear the upper load to achieve the effect of "three walls in one", which has certain economic benefits; BRIEF DESCRIPTION OF THE DRAWINGS

[0024] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0025] Figure 1 It is an I-shaped wall segment structure of the present invention;

[0026] Figure 2 It is a cap-type wall segment structure of the present invention;

[0027] Figure 3 The first staggered T-shaped wall segment structure and the second staggered T-shaped wall segment structure of the present invention;

[0028] Figure 4 The first L-shaped wall segment structure and the second L-shaped wall segment structure of the present invention;

[0029] Figure 5 It is the first grid-shaped underground continuous wall structure of the present invention;

[0030] Figure 6 The second grid-shaped underground continuous wall structure of the present invention;

[0031] Figure 7 This is the third grid-shaped underground continuous wall structure of the present invention;

[0032] Figure 8 This is the fourth grid-shaped underground continuous wall structure of the present invention;

[0033] In the figure, 1-first longitudinal wall section; 2-second longitudinal wall section; 3-first transverse partition wall section; 4-third longitudinal wall section; 5-fourth longitudinal wall section; 6-second transverse partition wall section; 7-fifth longitudinal wall section; 8-third transverse partition wall section; 9-sixth longitudinal wall section; 10-fourth transverse partition wall section; 11-eighth longitudinal wall section; 12-sixth transverse partition wall section; 13-seventh longitudinal wall section; 14-fifth transverse partition wall section; 15-first L-shaped wall segment structure; 16-second L-shaped wall segment structure; 17-first offset T-shaped wall segment structure; 18-second offset T-shaped wall segment structure; 19-cap-shaped wall segment structure; 20-I-shaped wall segment structure. DETAILED DESCRIPTION

[0034] In order to further explain the technical means and effects adopted by the present invention to achieve the predetermined invention purpose, the specific implementation method, structure, characteristics and effects of the present invention application are described in detail below in combination with the accompanying drawings and preferred embodiments.

[0035] The lattice underground continuous wall is assembled from two end wall segment structures and a plurality of groups of intermediate wall segment structures. The end wall segment structure is a cap-shaped wall segment structure (19) or an L-shaped wall segment structure. The intermediate wall segment structure is an I-shaped wall segment structure (20) or a staggered T-shaped wall segment structure. The L-shaped wall segment structure includes a first L-shaped wall segment structure (15) and a second L-shaped wall segment structure. One end wall segment structure is assembled from a first L-shaped wall segment structure (15) and a second L-shaped wall segment structure. The T-shaped wall segment structure includes a first staggered T-shaped wall segment structure (17) and a second staggered T-shaped wall segment structure (18). One first staggered T-shaped wall segment structure (17) and one second staggered T-shaped wall segment structure (18) are assembled into a group of intermediate wall segment structures.

[0036] Embodiment 1

[0037] like Figure 5As shown, a prefabricated grid-shaped underground continuous wall without internal support is characterized in that it includes a first grid-shaped underground continuous wall, wherein the first grid-shaped underground continuous wall includes an I-shaped wall segment structure (20) and a cover-shaped wall segment structure (19), and the first grid-shaped underground continuous wall is prefabricated by connecting the I-shaped wall segment structure (20) and the cover-shaped wall segment structure (19) through a cross steel sheet pile joint.

[0038] like Figure 1 As shown, the I-shaped wall section structure (20) comprises a first longitudinal wall section (1), a second longitudinal wall section (2) and a first transverse partition wall section (3), wherein the first transverse partition wall section (3) is disposed between the first longitudinal wall section (1) and the second longitudinal wall section (2), and the first longitudinal wall section (1), the second longitudinal wall section (2) and the first transverse partition wall section (3) are hollow inside and form an asymmetrical I-shape.

[0039] like Figure 2 As shown, the cover-type wall section structure (19) includes a third longitudinal wall section (4), a fourth longitudinal wall section (5) and a second transverse partition wall section (6), wherein the second transverse partition wall section (6) is connected to one side of the third longitudinal wall section (4) and the fourth longitudinal wall section (5) to prefabricate the cover-type wall section structure (19), and the third longitudinal wall section (4) is longer than the fourth longitudinal wall section (5).

[0040] Preferably, the width of the first grid-shaped underground continuous wall is less than 4 m.

[0041] Embodiment 2

[0042] like Figure 6 As shown, a prefabricated grid-shaped underground continuous wall without internal support comprises a second grid-shaped underground continuous wall, wherein the second grid-shaped underground continuous wall comprises a first offset T-shaped wall segment structure (17), a second offset T-shaped wall segment structure (18), a first L-shaped wall segment structure (15) and a second L-shaped wall segment structure (16), wherein the first offset T-shaped wall segment structure (17), the second offset T-shaped wall segment structure (18), the first L-shaped wall segment structure (15) and the second L-shaped wall segment structure (16) are prefabricated by connecting through cross steel plate joints.

[0043] like Figure 3As shown, the first offset T-shaped wall segment structure (17) is composed of a fifth longitudinal wall section (7) and a third transverse partition wall section (8), the third transverse partition wall section (8) is connected to a portion of the fifth longitudinal wall section (7) that is offset from the center to one side, the third transverse partition wall section (8) and the fifth longitudinal wall section (7) are hollow hole structures inside, a cross steel plate is preset at the end of the third transverse partition wall section (8), a cross steel plate is preset at the end of the fifth longitudinal wall section (7) that is at a greater vertical distance from the center line of the third transverse partition wall section (8), and a cross steel plate groove is reserved at the end of the fifth longitudinal wall section (7) that is at a smaller vertical distance from the center line of the third transverse partition wall section (8); The two-offset T-shaped wall section structure (18) is composed of a sixth longitudinal wall section (9) and a fourth transverse partition wall section (10), wherein the fourth transverse partition wall section (10) is connected to a portion of the sixth longitudinal wall section (9) at the other side of the center, and the fourth transverse partition wall section (10) and the sixth longitudinal wall section (9) are hollow hole structures inside, and a cross steel plate groove is reserved at the end of the fourth transverse partition wall section (10), and a cross steel plate groove is reserved at the end of the sixth longitudinal wall section (9) with a larger vertical distance from the center line of the fourth transverse partition wall section (10), and a cross steel plate is preset at the end of the sixth longitudinal wall section (9) with a smaller vertical distance from the center line of the fourth transverse partition wall section (10).

[0044] like Figure 4 As shown, the first L-shaped wall section structure (15) is prefabricated into an L-shape by the seventh longitudinal wall section (13) and the fifth transverse partition wall section (14), a cross steel plate is preset at the end of the seventh longitudinal wall section (13), and a cross steel plate groove is reserved at the end of the fifth transverse partition wall section (14); the second L-shaped wall section structure (16) is prefabricated into an L-shape by the eighth longitudinal wall section (11) and the sixth transverse partition wall section (12), the seventh longitudinal wall section (13) is shorter than the eighth longitudinal wall section (11), and cross steel plates are preset at the ends of the eighth longitudinal wall section (11) and the sixth transverse partition wall section (12).

[0045] Preferably, the width of the second grid-shaped underground continuous wall is greater than 4 m, the lengths of the fifth longitudinal wall section (7) and the sixth longitudinal wall section (9) are both less than 4 m, and the widths of the first offset T-shaped wall segment structure (17) and the second offset T-shaped wall segment structure (18) are both greater than 3 m.

[0046] Embodiment 3

[0047] like Figure 7 , 8As shown, on the basis of the first and second embodiments, the present invention can also form a third grid-shaped underground continuous wall and a fourth grid-shaped underground continuous wall. The third grid-shaped underground continuous wall can also be prefabricated by connecting an I-shaped wall segment structure (20), a first L-shaped wall segment structure (15) and a second L-shaped wall segment structure (16) through a cross steel plate joint; the fourth grid-shaped underground continuous wall is prefabricated by connecting a first offset T-shaped wall segment structure (17), a second offset T-shaped wall segment structure (18) and a cap-shaped wall segment structure (19) through a cross steel plate joint.

[0048] The present invention discloses a prefabricated grid-shaped underground continuous wall without internal support, which is formed by connecting a large number of underground continuous wall segments, and each underground continuous wall segment is connected by a cross steel plate joint. In order to improve the integrity of the grid-shaped underground continuous wall, the wall segment types are selected as I-shaped, T-shaped and L-shaped. Considering the limitations of the urban foundation pit construction site, four structural forms are designed, namely the first grid-shaped underground continuous wall, the second grid-shaped underground continuous wall, the third grid-shaped underground continuous wall and the fourth grid-shaped underground continuous wall. The joints of the four structures are asymmetrical in design to prevent shear failure along the unified joints.

[0049] The present invention forms a semi-gravity structure through a special lattice structure and the original soil inside it. It relies on itself to bear the water and soil pressure outside the pit during the foundation pit construction, thereby realizing the stability of the foundation pit without an internal support structure. The structure is prefabricated in a factory, and the surface of the wall section is smooth. In addition to protecting the stability of the foundation pit, after the construction is completed, it can also be directly used as the outer wall of the underground structure and bear the upper load to achieve the effect of "three walls in one", which has certain economic benefits.

[0050] After the construction of the main building is completed under the enclosure of the structure, the structure can be redeveloped and utilized. The partition walls of the grid-shaped underground continuous wall structure can be demolished to form two small space structures on both sides of the main structure. The inner and outer walls serve as the enclosure structures of the small foundation pits on both sides, making full use of the space of the partition walls. This structure can not only be used as an urban building foundation pit, but also for the construction of underground highways. The main road is built in the middle and auxiliary roads are built on both sides. It is safe, fast, economical and environmentally friendly.

[0051] Embodiment 4

[0052] A construction process of a prefabricated grid underground continuous wall without internal support, including guide wall construction, troughing, hoisting of prefabricated underground continuous walls, splicing of vertical underground continuous walls, connection of horizontal underground continuous walls and backfilling of hollow sections;

[0053] The guide wall construction process shown is: the guide wall cross section adopts an inverted L-shape, and is cast and cured twice. Compared with the ordinary guide wall, the guide wall is deepened in the construction process to make a deep guide wall, and the depth of the guide wall is greater than 2m, which enhances the overall stability of the guide wall;

[0054] The trenching construction process shown in the figure: During the trenching process, strengthen the testing of mud indicators and observe the trench. When the mud viscosity reaches 40-50s and the specific gravity is less than 1.25g / cm 3 When the water loss rate is less than 30mg / 30min and the pH value is between 8 and 10, the mud in the trench meets the standards. When the indicators are insufficient, the slurry should be replenished in time, and admixtures such as CMC should be added in time to increase the viscosity of the mud and improve the mud performance indicators. In order to ensure the stability of the trench wall, the load around the construction site should also be controlled. For equipment such as trenching machines, earthmoving vehicles and concrete mixers that must be close to the underground continuous wall, roadbed steel plates are laid on their moving routes to disperse the concentrated load. In order to keep large equipment away from the underground continuous wall as much as possible, crawler cranes with a large turning radius are used to hoist the underground continuous wall during construction. It is strictly forbidden to pile up soil or construction materials near the grid-shaped underground continuous wall.

[0055] The process of hoisting the prefabricated underground continuous wall is as follows: before the prefabricated underground continuous wall is hoisted, a force transmission pad is pre-pasted on the annular surface and the longitudinal surface of the prefabricated underground continuous wall. The length of each section of the prefabricated underground continuous wall is less than 10m. During prefabrication, hoisting positioning holes are reserved on both sides of the wall section of the underground continuous wall. The positioning holes are used to rotate the screws on the assembly fixing frame and push them into the fixing holes so that they are temporarily placed on the guide groove, which is convenient for the splicing of the upper and lower prefabricated underground continuous walls.

[0056] The splicing process of the vertical underground continuous wall is: using steel plate joints for connection, that is, the connection end plates embedded at the end faces of the upper and lower prefabricated wall sections are connected by groove welding and combined with steel bar anchoring. When the wall sections are manufactured in the factory, a certain number of dowel bars are reserved at the bottom of the upper prefabricated wall section, and steel bar holes corresponding to the dowel bars of the upper section are reserved at the top of the lower wall section. During on-site docking construction, the cementing material is first poured into the reserved holes of the lower wall section, and then the upper wall section is lowered to insert the steel bars into the reserved holes to form an anchoring connection, and then the connection end plates are connected by groove welding.

[0057] The horizontal underground continuous wall connection process is: using a cross steel plate joint connection, pre-embed half of the cross steel plate on one side of the wall section during the prefabrication process, and reserve a groove matching the other side of the cross steel plate on the other side. During construction, the side with the steel plate is butted against the side with the groove, and water-expandable waterproofing glue is applied to the groove part before the joint connection. After the lifting connection, the expanding waterproofing glue expands under the action of water to fill the entire gap and tightly connect the two wall sections, and work together to resist the water and soil pressure on the outside to achieve a waterproof and anti-seepage effect;

[0058] The hollow section backfilling process is: concrete grouting or soil backfilling is performed on the grooves reserved in the wall section and correspondingly connected to the cross steel plates.

[0059] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A prefabricated grid underground continuous wall without internal support, characterized in that: The lattice underground continuous wall is assembled from two end wall segment structures and a plurality of groups of intermediate wall segment structures, the end wall segment structure is a cap-shaped wall segment structure (19) or an L-shaped wall segment structure, the intermediate wall segment structure is an I-shaped wall segment structure (20) or a staggered T-shaped wall segment structure, the L-shaped wall segment structure includes a first L-shaped wall segment structure (15) and a second L-shaped wall segment structure (16), one end wall segment structure is assembled from a first L-shaped wall segment structure (15) and a second L-shaped wall segment structure (16), the T-shaped wall segment structure includes a first staggered T-shaped wall segment structure (17) and a second staggered T-shaped wall segment structure (18), and one of the first staggered T-shaped wall segment structure (17) and one of the second staggered T-shaped wall segment structure (18) are assembled into a group of intermediate wall segment structures; The I-shaped wall segment structure (20) comprises a first longitudinal wall section (1), a second longitudinal wall section (2) and a first transverse partition wall section (3), wherein the first transverse partition wall section (3) is arranged between the first longitudinal wall section (1) and the second longitudinal wall section (2), and the first longitudinal wall section (1), the second longitudinal wall section (2) and the first transverse partition wall section (3) are hollow inside and form an asymmetrical I-shaped structure; The cap-shaped wall segment structure (19) comprises a third longitudinal wall section (4), a fourth longitudinal wall section (5) and a second transverse partition wall section (6), wherein the second transverse partition wall section (6) is connected to one side of the third longitudinal wall section (4) and the fourth longitudinal wall section (5) to prefabricate the cap-shaped wall segment structure (19), and the third longitudinal wall section (4) is longer than the fourth longitudinal wall section (5); The first offset T-shaped wall segment structure (17) is composed of a fifth longitudinal wall section (7) and a third transverse partition wall section (8), wherein the third transverse partition wall section (8) is connected to a portion of the fifth longitudinal wall section (7) that is offset from the center to one side, and the third transverse partition wall section (8) and the fifth longitudinal wall section (7) are hollow hole structures inside, and a cross steel plate is preset at the end of the third transverse partition wall section (8), and a cross steel plate is preset at the end of the fifth longitudinal wall section (7) that is at a greater vertical distance from the center line of the third transverse partition wall section (8), and a cross steel plate groove is reserved at the end of the fifth longitudinal wall section (7) that is at a smaller vertical distance from the center line of the third transverse partition wall section (8); the second The offset T-shaped wall section structure (18) is composed of a sixth longitudinal wall section (9) and a fourth transverse partition wall section (10), wherein the fourth transverse partition wall section (10) is connected to a portion of the sixth longitudinal wall section (9) at the other side of the center, and the fourth transverse partition wall section (10) and the sixth longitudinal wall section (9) are hollow hole structures inside, and a cross steel plate groove is reserved at the end of the fourth transverse partition wall section (10), and a cross steel plate groove is reserved at the end of the sixth longitudinal wall section (9) with a larger vertical distance from the center line of the fourth transverse partition wall section (10), and a cross steel plate is preset at the end of the sixth longitudinal wall section (9) with a smaller vertical distance from the center line of the fourth transverse partition wall section (10); The first L-shaped wall section structure (15) is prefabricated into an L-shape by the seventh longitudinal wall section (13) and the fifth transverse partition wall section (14); a cross steel plate is preset at the end of the seventh longitudinal wall section (13); a cross steel plate groove is reserved at the end of the fifth transverse partition wall section (14); the second L-shaped wall section structure (16) is prefabricated into an L-shape by the eighth longitudinal wall section (11) and the sixth transverse partition wall section (12); the seventh longitudinal wall section (13) is shorter than the eighth longitudinal wall section (11); and cross steel plates are preset at the ends of the eighth longitudinal wall section (11) and the sixth transverse partition wall section (12).

2. The construction process of a prefabricated grid underground continuous wall without internal support as claimed in claim 1, characterized in that: It includes the process of guide wall construction, trenching, hoisting prefabricated underground continuous wall, vertical underground continuous wall splicing, horizontal underground continuous wall connection, and cross-section backfilling; The guide wall construction process is as follows: the guide wall cross section adopts an inverted L-shape, two times of mold casting and curing, and the guide wall is deepened during the construction process, and the depth of the guide wall is greater than 2m; The trenching process: when trenching, use mud with high viscosity, low water loss and tough mud skin surface; during the trenching process, test the mud index and observe the trench. When the mud viscosity reaches 40-50s and the specific gravity is less than 1.25g / cm 3 When the water loss rate is less than 30mg / 30min and the pH value is between 8 and 10, the mud in the tank meets the standard. If the index is insufficient, admixtures should be added in time to meet the mud performance index; The process of hoisting the prefabricated underground continuous wall is as follows: before the prefabricated underground continuous wall is hoisted, a force transmission pad is pre-pasted on the annular surface and the longitudinal surface of the prefabricated underground continuous wall. The length of each section of the prefabricated underground continuous wall is less than 10m. During prefabrication, hoisting positioning holes are reserved on both sides of the wall section of the underground continuous wall. The positioning holes are used to rotate the screws on the assembly fixing frame and push them into the fixing holes so that they are temporarily placed on the guide groove, which is convenient for the splicing of the upper and lower prefabricated underground continuous walls. The splicing process of the vertical underground continuous wall is: using steel plate joints for connection, that is, the connection end plates embedded at the end faces of the upper and lower prefabricated wall sections are connected by groove welding and combined with steel bar anchoring. When the wall sections are manufactured in the factory, a certain number of dowel bars are reserved at the bottom of the upper prefabricated wall section, and steel bar holes corresponding to the dowel bars of the upper section are reserved at the top of the lower wall section. During on-site docking construction, the cementing material is first poured into the reserved holes of the lower wall section, and then the upper wall section is lowered to insert the steel bars into the reserved holes to form an anchoring connection, and then the connection end plates are connected by groove welding. The horizontal underground continuous wall connection process is: using a cross steel plate joint connection, pre-embed half of the cross steel plate on one side of the wall section during the prefabrication process, and reserve a groove matching the cross steel plate on the other side, and dock the side with the cross steel plate with the side with the groove during construction, and apply water-expandable waterproofing glue on the groove part before the joint connection, and after the hoisting connection, the expanding waterproofing glue expands under the action of water to fill the entire gap and tightly connect the two wall sections; The hollow section backfilling process is: backfilling the hollow section of the structure by concrete grouting or soil.

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