A super-deep prestressed diaphragm wall in cobblestone layer and its construction method

Abstract

The present invention discloses an ultra-deep prestressed diaphragm wall in a sandy pebble layer and its construction method, including the ground, a steel reinforcement cage, and a prestressed tensioning assembly. A guide wall is installed inside the ground. Below the guide wall, there is a reinforced grotto wall high-pressure jet grouting pile. A capping beam is arranged between the tops of the guide walls. An array of wooden supports is evenly installed on the upper and lower sides of the capping beam. Below the capping beam, a diaphragm wall is poured between the guide walls. Beneficial effects: The present invention uses a reinforced concrete structure with large wall stiffness and good integrity, which can effectively resist various external forces under complex geological conditions such as sandy pebble layers, ensure the stability of the foundation pit and the main structure, effectively prevent groundwater leakage, and ensure the construction safety inside the foundation pit. The diaphragm wall of the present invention adopts mechanized construction with a fast grooving speed and high concrete pouring efficiency, which can significantly shorten the construction period, improve the project progress, and reduce the impact on the surrounding environment.

Description

Technical Field

[0001] The present invention relates to the technical field of diaphragm walls, and in particular, to an ultra-deep prestressed diaphragm wall in a sandy pebble layer and a construction method thereof. Background Art

[0002] As an important foundation pit support structure, diaphragm walls are widely used in projects such as subway stations and deep foundation pits of high-rise buildings, and are particularly important in the construction of sandy pebble layers with complex geological conditions. Some components of the diaphragm wall can be prefabricated in the factory to reduce the on-site pouring time, highly matching the "factory prefabrication + on-site assembly" mode of prefabricated buildings, shortening the overall construction period. At the same time, prefabricated diaphragm wall components can reduce energy-consuming links such as on-site vibration and curing, and shortening the construction period can reduce the carbon emissions of construction machinery; the segmented construction of the diaphragm wall can be coordinated with the modular design of the main structure of the prefabricated building to achieve synchronous construction of the foundation pit support and the above-ground structure, improving the overall efficiency of the project; as a deep foundation pit support structure, the high stiffness characteristics of the diaphragm wall can form a stable mechanical system with the main structure of the prefabricated building, especially suitable for super high-rise buildings; the anti-seepage and water-stop function of the diaphragm wall can avoid the impact of deep foundation pit dewatering on the surrounding environment, reduce groundwater extraction and ground settlement, meeting the ecological protection requirements of green buildings; the deep foundation pit supported by the diaphragm wall provides a reliable space for underground garages, equipment rooms, etc., improving land utilization rate, meeting the concept of "compact city" of green buildings.

[0003] Constructing diaphragm walls in sandy pebble layers faces many challenges, mainly including: poor formation stability: The sandy pebble layer has the characteristics of large porosity and strong water permeability, and the groove wall is prone to collapse during construction, making it difficult to control the verticality of the groove. High construction difficulty: The content of pebbles in the sandy pebble layer is high, and the grooving equipment is prone to encounter greater resistance during excavation, and the pebbles have an adverse effect on the mud wall protection effect. Low construction efficiency: Traditional construction methods are difficult to quickly adapt to different formation conditions, resulting in low grooving efficiency and long construction periods.

[0004] In response to the problems in the related art, no effective solution has been proposed yet. Summary of the Invention

[0005] Aiming at the deficiencies in the prior art, the purpose of the present invention is to propose an ultra-deep prestressed diaphragm wall in a sandy pebble layer and a construction method thereof.

[0006] To achieve the above object, the present invention is realized by the following technical solutions. A super-deep prestressed diaphragm wall in sandy pebble layer includes the ground, a steel reinforcement cage and a prestressed tensioning assembly. A guide wall is installed in the ground. Under the guide wall, there are high-pressure jet grouting piles for strengthening the groove wall. A capping beam is arranged between the tops of the guide walls. Several groups of wooden supports are evenly installed on the upper and lower sides of the capping beam. Under the capping beam and between the guide walls, a diaphragm wall is cast. On the top of the capping beam, a reinforced concrete retaining wall is installed. Several groups of prestressed anchor rods are installed on the diaphragm wall through steel pedestals.

[0007] Preferably, transverse truss bars and longitudinal truss bars are arranged in the steel reinforcement cage. A conduit is arranged inside the steel reinforcement cage. The conduit is fixed in the steel reinforcement cage through conduit positioning bars. I-beams are installed at both ends of the steel reinforcement cage. Grout stop plates and full-length grouting pipes are arranged on both sides of the I-beams.

[0008] Preferably, the prestressed tensioning assembly includes a thick steel plate welded in the steel reinforcement cage. Anchorage devices are arranged on the thick steel plate. A backing plate is arranged at the connection between the thick steel plate and the anchorage devices. Wedge blocks connected to the steel reinforcement cage are installed on the backing plate. Bracing bars are welded in the transverse truss bars. Embedded sleeves are arranged in the steel reinforcement cage.

[0009] Preferably, the guide walls are arranged on both sides of the diaphragm wall and have an "L"-shaped cross-section. The lower ends of the guide walls are located on the underground rock and soil, and the ears are connected to the concrete road surface.

[0010] A construction method for a super-deep prestressed diaphragm wall in sandy pebble layer specifically includes the following steps:

[0011] S1. Fabricate the guide wall: Divide the L-shaped guide wall into a transverse member and a vertical member. First, fix the two vertical members on both sides with steel frames and position them according to the on-site lofting, and then connect them to the transverse member to form a complete guide wall.

[0012] S2. Prepare the slurry: Mix sodium-based bentonite, basalt fiber and an appropriate amount of brine and stir for 2 hours to obtain a high-performance slurry suitable for the sandy pebble layer, thereby forming a high-performance slurry for protecting the wall during the trench excavation of the diaphragm wall.

[0013] S3. Trench excavation construction: Adopt the combined grab and milling method for trench excavation construction. Along the guide wall described in S1, excavate a trench under the condition of the high-performance slurry for protecting the wall in S2. During the trench excavation process, ensure the verticality of the trench wall, and use the heavy hammer method or ultrasonic detection method for real-time monitoring.

[0014] S4. Bottom cleaning and replacement: After the trench is formed, use the centrifugal pump, mud purification, and pipeline system equipped with the milling machine to suction the sediment at the bottom of the trench for bottom cleaning and replacement, remove the sediment and unqualified mud at the bottom of the trench to ensure the cleanliness of the trench bottom, and use a wall brushing device to clean the joint part to ensure the joint quality;

[0015] S5. Steel reinforcement cage fabrication and hoisting: Fabricate the steel reinforcement cage according to the size after the trench is formed, carry out the hoisting work through the crane, and strictly control the hoisting angle and speed during the hoisting process to ensure the smooth insertion of the steel reinforcement cage into the trench;

[0016] S6. Concrete pouring and prestress tensioning: Use an anti-vibration concrete grouting device to pour concrete into the trench, and make the concrete wrap the steel reinforcement cage in the trench. After the concrete reaches the design strength, carry out prestress tensioning to improve the bearing capacity of the wall.

[0017] The present invention provides a super-deep prestressed diaphragm wall in sandy gravel layer and its construction method, and the beneficial effects are as follows:

[0018] The present invention uses a reinforced concrete structure, which has a large wall stiffness and good integrity. It can effectively resist various external forces under complex geological conditions such as sandy gravel layers, ensure the stability of the foundation pit and the main structure, can effectively prevent groundwater leakage, and ensure the construction safety in the foundation pit. The diaphragm wall of the present invention adopts mechanized construction, with a fast trench forming speed and high concrete pouring efficiency, which can significantly shorten the construction period, improve the project progress, and reduce the impact on the surrounding environment. As the core technology of deep foundation pit engineering, the diaphragm wall realizes efficient cooperation with prefabricated buildings, and at the same time, with its environmental protection and energy-saving characteristics, it deeply fits the green building goal. It not only improves the technical economy of construction projects, but also promotes the upgrading of the construction industry to a sustainable development model, which has important significance for promoting green and low-carbon building materials and green construction methods, and further developing prefabricated buildings and green buildings. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required to be used in the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0020] Figure 1 is the sectional view of the super-deep prestressed diaphragm wall in sandy gravel layer of the present invention;

[0021] Figure 2 is the detailed drawing of the diaphragm wall guide wall practice of the present invention;

[0022] Figure 3 is the detailed drawing of the standard groove section practice of the diaphragm wall of the present invention;

[0023] Figure 4 It is the detailed drawing of the method for embedding casing pipes in the diaphragm wall of the present invention;

[0024] Figure 5 It is the front view of the anti-shake concrete grouting device of the present invention;

[0025] Figure 6 It is the structural schematic diagram of the concrete mixing component of the present invention;

[0026] Figure 7 It is the structural schematic diagram of the anti-shake support component of the present invention.

[0027] In the figure:

[0028] 1. Diaphragm wall; 2. Guide wall; 3. Reinforced concrete retaining wall; 4. Capping beam; 5. High-pressure jet grouting pile for strengthening the groove wall; 6. Prestressed anchor; 7. Steel pedestal; 8. Ground; 9. Wood support; 10. Transverse truss bars; 11. Grout stop plate; 12. I-beam; 13. Conduit; 14. Conduit positioning bars; 15. Longitudinal grouting pipe; 16. Longitudinal truss bars; 17. Thick steel plate; 18. Anchor; 19. Base plate; 20. Wedge; 21. Bracing bars; 22. Embedded casing pipe; 23. Mobile rack; 24. Concrete mixing component; 25. Pre-stored mixing barrel; 26. Discharge control valve; 27. Booster pump; 28. Booster pipe; 29. Grouting pipe; 30. Anti-shake support component; 31. Rotating wheel; 32. Umbrella-shaped blade; 33. Rotating shaft; 34. Motor; 35. Support plate; 36. Bearing; 37. Rotating rod; 38. Bevel gear; 39. Support sleeve; 40. Sector blade; 41. Connecting cross plate; 42. Mobile table; 43. Through hole; 44. Elastic limiting inner ring; 45. Activity groove; 46. Slide block; 47. Support side plate; 48. Connecting block; 49. Connecting rod; 50. Guide plate; 51. Moving block; 52. Elastic block; 53. Spring. Detailed implementation manners

[0029] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0030] Please refer to Figures 1-4, the present invention provides an ultra - deep prestressed diaphragm wall in sandy pebble layer, which includes the ground 8, a steel reinforcement cage and a prestressed tensioning assembly. A guide wall 2 is installed inside the ground 8. A reinforced cut - off wall high - pressure jet grouting pile 5 is arranged below the guide wall 2. A capping beam 4 is arranged between the tops of the guide walls 2. A number of groups of wooden supports 9 are evenly installed on the upper and lower sides of the capping beam 4. A diaphragm wall 1 is cast between the guide walls 2 below the capping beam 4. A reinforced concrete retaining wall 3 is installed on the top of the capping beam 4. A number of groups of prestressed anchor rods 6 are installed on the diaphragm wall 1 through steel pedestals 7. Before the production of the diaphragm wall, the guide wall 2 is made first. After the guide wall 2 is completed, the reinforced cut - off wall high - pressure jet grouting piles 5 on both sides of the diaphragm wall are constructed. The trench is formed by the combined grab - milling method. The steel reinforcement cage is fabricated, and the lifting angle and speed are strictly controlled during the hoisting process to ensure that the steel reinforcement cage smoothly enters the trench. After the steel reinforcement cage smoothly enters the trench, concrete is poured, and finally the diaphragm wall 1 is formed.

[0031] In one embodiment, please refer to the attached drawings of the specification Figure 3 As shown, transverse truss bars 10 and longitudinal truss bars 16 are arranged inside the steel reinforcement cage. A conduit 13 is arranged inside the steel reinforcement cage. The conduit 13 is fixed inside the steel reinforcement cage through conduit positioning bars 14. I - beams 12 are installed at both ends of the steel reinforcement cage. Grout - stopping plates 11 and full - length grouting pipes 15 are arranged on both sides of the I - beams 12.

[0032] In one embodiment, please refer to the attached drawings of the specification Figure 4 As shown, the prestressed tensioning assembly includes a thick steel plate 17 welded inside the steel reinforcement cage. An anchor 18 is arranged on the thick steel plate 17. A backing plate 19 is arranged at the connection between the thick steel plate 17 and the anchor 18. A skew iron 20 connected to the steel reinforcement cage is installed on the backing plate 19. Bracing bars 21 are welded inside the transverse truss bars 10. Embedded sleeves 22 are arranged inside the steel reinforcement cage.

[0033] In one embodiment, please refer to the attached drawings of the specification Figure 1 As shown, the guide wall 2 is arranged on both sides of the diaphragm wall 1, and its cross - sectional shape is "L". The lower end of the guide wall 2 is located on the underground rock and soil, and the ear is connected to the concrete road surface. The guide wall 2 is placed on both sides of the diaphragm wall 1, with a cross - sectional shape of "L". The lower end of the guide wall 2 is located on the underground rock and soil, and the ear is connected to the concrete road surface, making it serve as the guiding and supporting structure for the trench - forming equipment;

[0034] In one embodiment, please refer to the attached drawings of the specification Figure 5As shown, the anti-shake concrete grouting device includes a moving frame 23. Moving wheels are installed at the bottom of the moving frame 23. A pre-storage mixing barrel 25 is installed on the moving frame 23. A concrete mixing assembly 24 is installed on the pre-storage mixing barrel 25. An outlet control valve 26 is installed on the moving frame 23 below the pre-storage mixing barrel 25. A booster pump 27 is installed on the moving frame 23. A temporary storage cavity is communicated below the outlet control valve 26. The output end of the booster pump 27 is communicated with the temporary storage cavity through a booster pipe 28. A metal delivery pipe is provided at the bottom of the temporary storage cavity. An anti-shake support assembly 30 is installed outside the metal delivery pipe. The other end of the metal delivery pipe is communicated with a grouting pipe 29; the moving frame 23 cooperates with the moving wheels to facilitate the movement of the entire grouting equipment, thus facilitating the concrete grouting work after grooving. The pre-storage mixing barrel 25 cooperates with the concrete mixing assembly 24 to ensure the uniformity of the concrete. The booster pump 27 cooperates with the booster pipe 28 to increase the pressure of the conveyed concrete and improve its conveying speed. The anti-shake support assembly 30 can effectively avoid the pipeline shaking when the pipeline conveys concrete;

[0035] In one embodiment, please refer to the attached drawings of the specification Figure 6 As shown, the concrete mixing assembly 24 includes an outer shell. A rotating wheel 31 is rotatably installed in the outer shell through a rotating shaft 33. One end of the rotating shaft 33 is connected to a motor 34 fixed on the outer wall of the outer shell. Umbrella-shaped blades 32 are integrally connected to both sides of the rotating wheel 31. A support plate 35 is fixedly installed in the pre-storage mixing barrel 25. Two bearings 36 are symmetrically embedded and installed on the support plate 35. The inner ring of the bearing 36 is fixedly penetrated and installed with a rotating rod 37. The top end of the rotating rod 37 is fixedly connected to a bevel gear 38 meshing with the umbrella-shaped blade 32. Two support sleeves 39 are symmetrically installed on the rotating rod 37 below the support plate 35. An array of fan-shaped blades 40 is connected between the support sleeves 39; the motor 34 drives the rotating wheel 31 to rotate in the outer shell, so that the umbrella-shaped blades 32 rotate. Since the bevel gear 38 meshes with the umbrella-shaped blade 32, the bevel gear 38 drives the rotating rod 37 to rotate. The rotating rod 37 fixedly penetrates the inner ring of the bearing 36, so that the rotating rod 37 can rotate stably. The rotating rod 37 drives the fan-shaped blades 40 on the support sleeve 39 to rotate, so as to realize the full stirring and mixing of the concrete.

[0036] In one embodiment, please refer to the attached drawings of the specification Figure 7As shown, the anti-shake support assembly 30 includes two connecting cross plates 41 fixed on the moving frame 23. A moving table 42 is movably arranged between the connecting cross plates 41. A through hole 43 is provided at the center of the moving table 42. An elastic limiting inner ring 44 is arranged in the through hole 43. The metal conveying pipe passes through the through hole 43 and is limited by the elastic limiting inner ring 44. Moving grooves 45 are formed in the inner walls of the connecting cross plates 41. Sliders 46 matching the moving grooves 45 are arranged at the upper and lower ends of the moving table 42. Support side plates 47 are fixedly connected to both ends of the moving groove 45. Springs 53 are connected between the support side plates 47 and the moving table 42. Connecting blocks 48 are symmetrically arranged on both the support side plates 47 and the moving table 42. Two guide plates 50 are symmetrically installed between the connecting cross plates 41. An activity cavity is formed in the guide plate 50. A moving block 51 is slidably arranged in the activity cavity. A connecting rod 49 is movably connected between the moving block 51 and the connecting block 48 through a rotating shaft. Elastic blocks 52 are arranged at both ends of the activity cavity. During use, the metal conveying pipe is passed through the through hole 43 on the moving table 42 and fixed in cooperation with the elastic limiting inner ring 44. When the metal conveying pipe conveys concrete and generates vibrations, due to the limitation of the connecting cross plates 41, it will not generate up-and-down vibrations. For the case of left-and-right vibrations, when it vibrates, the moving table 42 will vibrate to the left and right sides. Thus, under the action of the connecting rod 49, the moving block 51 generates a certain amount of displacement in the activity cavity in the guide plate 50, and absorbs its kinetic energy after touching the elastic block 52, canceling the generated left-and-right swing. At the same time, springs 53 are also provided for auxiliary shock absorption, thus effectively avoiding the vibration problem generated during the concrete pipeline conveying.

[0037] In practical applications, by installing a guide wall 2 in the ground 8 and arranging a reinforced groove wall high-pressure jet grouting pile 5 below the guide wall 2, the structural stability in the horizontal direction is increased through the action of the capping beam 4. The diaphragm wall 1 is formed by pouring below the capping beam 4 between the guide walls 2. The present invention uses a reinforced concrete structure with large wall stiffness and good integrity, which can effectively resist various external forces under complex geological conditions such as sandy pebble layers, ensuring the stability of the foundation pit and the main structure, effectively preventing groundwater leakage, and ensuring the construction safety in the foundation pit. The diaphragm wall of the present invention adopts mechanized construction with a fast grooving speed and high concrete pouring efficiency, which can significantly shorten the construction period, improve the project progress, and reduce the impact on the surrounding environment.

[0038] Although this specification is described according to the embodiments, not each embodiment only contains an independent technical solution. This narrative way of the specification is only for clarity. Those skilled in the art should regard the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. A construction method for an ultra - deep prestressed diaphragm wall in cobble layer, characterized in that, For the construction of ultra - deep prestressed diaphragm walls in sandy pebble layers, it specifically includes the following steps: S1. Making the guide wall: Divide the L - shaped guide wall into two parts, a horizontal component and a vertical component. First, fix the two side vertical components with a steel frame and position them according to the on - site layout, and then connect them to the horizontal component to form a complete guide wall (2); S2. Making the slurry: Mix sodium - based bentonite, basalt fiber, and an appropriate amount of brine and stir for 2 hours to obtain a high - performance slurry suitable for the sandy pebble layer, thereby forming a high - performance slurry for protecting the trench wall during the construction of the diaphragm wall; S3. Trenching construction: Adopt the combined grab - milling trenching method for trenching construction. Along the guide wall (2) described in S1, excavate a trench under the condition of the high - performance slurry for protecting the trench wall in S2. During the trenching process, ensure the verticality of the trench wall and use the heavy - hammer method or ultrasonic detection method for real - time monitoring; S4. Bottom cleaning and replacement: After trenching is completed, use the centrifugal pump, slurry purification, and pipeline system supporting the milling machine to suck the sediment at the bottom of the trench for bottom cleaning and replacement, remove the sediment and unqualified slurry at the bottom of the trench to ensure the cleanliness of the bottom of the trench, and use a brush wall device to clean the joint part to ensure the joint quality; S5. Making and hoisting the steel cage: Make the steel cage according to the size after trenching, and carry out the hoisting work with a crane. During the hoisting process, strictly control the hoisting angle and speed to ensure that the steel cage smoothly enters the trench; S6. Concrete pouring and prestress tensioning: Use an anti - vibration concrete grouting device to pour concrete into the trench and make the concrete wrap the steel cage in the trench. After the concrete reaches the design strength, carry out prestress tensioning to improve the bearing capacity of the wall; The ultra - deep prestressed diaphragm wall in the sandy pebble layer includes: the ground (8), the steel cage, and the prestress tensioning assembly. A guide wall (2) is installed in the ground (8). A reinforced jet - grouting pile (5) for strengthening the trench wall is arranged below the guide wall (2). A capping beam (4) is arranged between the tops of the guide walls (2). A number of groups of wooden supports (9) are evenly installed on the upper and lower sides of the capping beam (4). A diaphragm wall (1) is poured between the guide walls (2) below the capping beam (4). A reinforced concrete retaining wall (3) is installed on the top of the capping beam (4). A number of groups of prestressed anchor rods (6) are installed on the diaphragm wall (1) through steel pedestals (7); The anti-vibration concrete grouting device includes a mobile frame (23). The bottom of the mobile frame (23) is equipped with mobile wheels. A pre-storage mixing barrel (25) is installed on the mobile frame (23). A concrete mixing assembly (24) is installed on the pre-storage mixing barrel (25). Below the pre-storage mixing barrel (25) and on the mobile frame (23) is installed a discharge control valve (26). A booster pump (27) is installed on the mobile frame (23). The lower part of the discharge control valve (26) is communicated with a temporary storage cavity. The output end of the booster pump (27) is communicated with the temporary storage cavity through a booster pipe (28). The bottom of the temporary storage cavity is provided with a metal delivery pipe. An anti-vibration support assembly (30) is installed outside the metal delivery pipe. The other end of the metal delivery pipe is communicated with a grouting pipe (29). The concrete mixing assembly (24) includes an outer shell. Inside the outer shell, a rotating wheel (31) is rotatably installed through a rotating shaft (33). One end of the rotating shaft (33) is connected to a motor (34) fixed on the outer wall of the outer shell. Umbrella-shaped blades (32) are integrally connected to both sides of the rotating wheel (31). A support plate (35) is fixedly installed inside the pre-storage mixing barrel (25). Two bearings (36) are symmetrically embedded and installed on the support plate (35). The inner ring of the bearing (36) is fixedly penetrated and installed with a rotating rod (37). The top end of the rotating rod (37) is fixedly connected to a bevel gear (38) meshing with the umbrella-shaped blade (32). Two support sleeves (39) are symmetrically installed on the rotating rod (37) below the support plate (35). A plurality of groups of fan-shaped blades (40) are connected between the support sleeves (39).

2. The construction method of an ultra-deep prestressed diaphragm wall in cobble layer according to claim 1, characterized in that Transverse truss bars (10) and longitudinal truss bars (16) are arranged inside the steel reinforcement cage. A conduit (13) is arranged inside the steel reinforcement cage. The conduit (13) is fixed inside the steel reinforcement cage through conduit positioning bars (14). I-beams (12) are installed at both ends of the steel reinforcement cage. Stop grouting plates (11) and full-length grouting pipes (15) are arranged on both sides of the I-beam (12).

3. The construction method of an ultra-deep prestressed diaphragm wall in a sandy pebble layer according to claim 2, characterized in that, The prestressed tensioning assembly includes a thick steel plate (17) welded inside the steel reinforcement cage. Anchors (18) are arranged on the thick steel plate (17). A backing plate (19) is arranged at the connection between the thick steel plate (17) and the anchor (18). A skew iron (20) connected to the steel reinforcement cage is installed on the backing plate (19). Bracing bars (21) are welded inside the transverse truss bar (10). Embedded sleeves (22) are arranged inside the steel reinforcement cage.

4. The construction method of an ultra-deep prestressed diaphragm wall in cobblestone layer according to claim 3, characterized in that, The guide walls (2) are arranged on both sides of the diaphragm wall (1) and have an "L"-shaped cross-section. The lower ends of the guide walls (2) are located on the underground rock and soil and are connected to the concrete road surface on the side.

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