A method for safety treatment of underground continuous wall intrusion

Abstract

The application discloses a kind of underground continuous wall intrusion safety processing method, specifically includes: determining continuous wall intrusion section position, erecting support beam and surrounding purlin on continuous wall intrusion section, making intrusion section structure bottom plate and non-intrusion section structure plate group, making reinforcing pile after continuous wall intrusion section, and gradually removing surrounding purlin and support beam with the progress of chiseling, in turn pouring intrusion section structure middle plate and intrusion section structure top plate.The method can ensure that the ability of underground enclosure structure to resist soil pressure does not decrease after the wall of the intrusion part of the underground continuous wall is chiseled without affecting the construction period, ensuring the safety of the foundation pit during construction.

Description

Technical Field

[0001] This invention relates to the field of underground retaining structure technology, and in particular to a method for handling the encroachment safety of underground diaphragm walls. Background Technology

[0002] Currently, most subway construction technology in China is underground, with the retaining structure and side walls forming a composite wall as the main structural form of stations. Among the retaining structures, diaphragm walls have good rigidity and play a significant role in the stability of the excavation pit. However, diaphragm wall construction is heavily influenced by geological conditions, with hole collapse being particularly common in water-replenished gravel and sand layers. Hole collapse is prone to occur during trenching, and it is difficult to avoid section collapse, leading to problems such as section displacement and tilting. Furthermore, during the excavation of the excavation pit, it is discovered that the quality of the diaphragm walls is poor, even encroaching on the internal structural boundary of the station, ultimately affecting train operation.

[0003] Existing methods for dealing with the encroaching portions of diaphragm walls generally involve directly chiseling away the encroaching portion, smoothing it with mortar, and then providing some support. For example, Chinese patent application number 202010690006.1 discloses a method for repairing and sealing defects in diaphragm walls. This method includes: determining the defective portion of the diaphragm wall, analyzing the cause of the defect, and formulating defect treatment measures based on the cause. The method for treating protruding portions (which can also be considered as encroaching portions) involves chiseling down the protruding portion and smoothing it with M10 mortar. While this method can effectively treat the encroaching portion, it reduces the diaphragm wall's ability to resist earth pressure, making it highly susceptible to foundation pit collapse and causing loss of life and property. As for the application's suggestion to spray or pour concrete on the encroaching portion depending on the cause of the encroachment, this approach does not address how to handle the infringement of the underground structure's construction boundary caused by the encroached portion. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to overcome the shortcomings of the prior art and provide a method for safe treatment of diaphragm wall encroachment that can ensure that the ability of the underground retaining structure to resist soil pressure does not decrease after the wall of the encroaching part of the diaphragm wall is removed, ensure the safety of the foundation pit, and not affect the overall construction progress.

[0005] To solve the above-mentioned technical problems, the present invention adopts the following technical solution:

[0006] A method for handling the encroachment safety of underground diaphragm walls specifically includes the following steps:

[0007] S1: While excavating the foundation pit, monitor the encroachment data of the diaphragm wall to determine the location of the non-encroachment section and the encroachment section of the diaphragm wall;

[0008] S2: While the foundation pit is being excavated, a waler is erected on the encroaching section of the continuous wall, and the supporting beam is erected on the waler;

[0009] S3: After the foundation pit is excavated, the bottom slab of the encroaching section structure in the encroaching section structure slab group is constructed first, and then the non-encroaching section structure slab group connected to the non-encroaching section of the continuous wall is constructed. The encroaching section structure slab group includes an encroaching section structure bottom slab, an encroaching section structure middle slab, and an encroaching section structure top slab located at the bottom, middle, and top of the encroaching section of the continuous wall, respectively. The non-encroaching section structure slab group includes a non-encroaching section structure bottom slab, a non-encroaching section structure middle slab, and a non-encroaching section structure top slab located at the bottom, middle, and top of the non-encroaching section of the continuous wall, respectively. The non-encroaching section structure slab group and the encroaching section structure slab group play the role of supporting the foundation pit and bearing the load.

[0010] S4: Construct reinforcing piles on the side of the continuous wall encroaching section away from the foundation pit;

[0011] S5: The encroaching wall of the continuous wall encroaching section is gradually removed from bottom to top, and the waler and the support beam are gradually removed as the removal progresses. The middle slab and the top slab of the encroaching section structure are then poured in sequence.

[0012] As a further improvement to the above technical solution: In step S2: at least one waler is provided between the bottom plate of the encroachment section structure and the middle plate of the encroachment section structure, and at least one waler is provided between the middle plate of the encroachment section structure and the top plate of the encroachment section structure.

[0013] As a further improvement to the above technical solution: in step S2: concrete is filled into the gap between the waler and the continuous wall encroachment section.

[0014] As a further improvement to the above technical solution: In step S2: the concrete is early-strength concrete, and the strength grade of the concrete is greater than the strength grade of the concrete used in the underground continuous wall.

[0015] As a further improvement to the above technical solution: a hole is provided between the encroaching section structural plate assembly and the encroaching part of the diaphragm wall encroaching section, and the transverse steel bars in the encroaching section structural plate assembly parallel to the length direction of the diaphragm wall are reserved with sufficient lap length on both sides of the hole, and the longitudinal steel bars in the encroaching section structural plate assembly perpendicular to the length direction of the diaphragm wall are reserved with mechanical joints at the edge of the hole.

[0016] As a further improvement to the above technical solution: a waterproof layer is provided on the side of the hole.

[0017] As a further improvement to the above technical solution: a top rod is provided in the hole to connect the continuous wall encroachment section and the encroachment section structural plate assembly.

[0018] As a further improvement to the above technical solution: In step S5, the detailed steps are as follows:

[0019] a) First, remove the encroaching wall of the continuous wall encroaching section located between the bottom slab of the encroaching section structure and the middle slab of the encroaching section structure. Then, remove the waler and the support beam located in this section. Next, remove the top bracing and the waterproof layer on the bottom slab of the encroaching section structure. Connect the transverse steel bars and the longitudinal steel bars. Finally, pour concrete into the hole in the bottom slab of the encroaching section structure.

[0020] b): Pour the middle slab of the encroaching section structure. After it reaches the predetermined strength, remove the encroaching wall of the continuous wall encroaching section between the middle slab of the encroaching section structure and the top slab of the encroaching section structure. Then, remove the walers and the supporting beams located in this section. Next, remove the top bracing on the middle slab of the encroaching section structure. Connect the transverse steel bars and the longitudinal steel bars. Finally, pour concrete into the holes of the middle slab of the structure.

[0021] c): Pour the top slab of the encroachment section structure.

[0022] As a further improvement to the above technical solution: both the waler and the support beam are steel components.

[0023] As a further improvement to the above technical solution: the top support rod is a steel component.

[0024] Compared with the prior art, the advantages of the present invention are as follows: The method for safe handling of diaphragm wall encroachment during the excavation stage in this invention infers the encroachment status of the diaphragm wall from monitoring and measurement data, determines the location of the encroaching section, and, as the excavation progresses, installs walers and support beams on the encroaching section as reinforcement measures. This not only supports the excavation pit but also ensures that the encroaching wall section does not collapse during the removal process. After the excavation is completed, a structural base plate for the encroaching section and a structural slab assembly for the non-encroaching section are constructed to connect the diaphragm wall, which is beneficial for the standardization of the two sides of the encroaching section. The stability of the diaphragm wall is ensured by constructing reinforcing piles after the encroachment section of the diaphragm wall is removed to withstand the earth pressure. This ensures that the reinforcing piles can bear the remaining earth pressure after the encroachment wall is removed, thus improving the stability of the foundation pit. The wall of the encroachment section of the diaphragm wall is gradually removed from bottom to top, and the walers and support beams are gradually removed as the removal progresses. The middle slab and the top slab of the encroachment section structure are poured in sequence, ensuring the continuity of the construction process. Moreover, the construction work of other standard sections of diaphragm walls can still be carried out while dealing with the encroachment section of the diaphragm wall, without affecting the overall construction period. Attached Figure Description

[0025] Figure 1 This is a construction flowchart of the underground continuous wall encroachment safety treatment method of the present invention.

[0026] Figure 2 This is a construction plan view of the underground continuous wall encroachment safety treatment method of the present invention.

[0027] Figure 3 yes Figure 2 A magnified view of part A.

[0028] Figure 4 yes Figure 2 BB-direction cross-section.

[0029] Figure 5 yes Figure 4 Cross-sectional view along the CC direction.

[0030] Figure 6 A schematic diagram of the reinforcement structure for the underground continuous wall encroachment safety treatment method of the present invention.

[0031] The labels in the diagram represent: 1. Diaphragm wall; 11. Unenclosed section of diaphragm wall; 12. Enclosed section of diaphragm wall; 2. Structural slab assembly of unenclosed section; 21. Top slab of unenclosed section; 22. Middle slab of unenclosed section; 23. Bottom slab of enclosed section; 3. Structural slab assembly of enclosed section; 31. Top slab of enclosed section; 32. Middle slab of enclosed section; 33. Bottom slab of enclosed section; 4. Hole; 41. Top brace; 42. Waterproof layer; 43. Transverse reinforcement; 44. Longitudinal reinforcement; 441. Mechanical joint; 5. Reinforcing pile; 6. Support beam; 7. Waler; 8. Concrete. Detailed Implementation

[0032] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. It should be noted that, unless the context clearly indicates otherwise, words such as "a," "an," "an," and / or "the" do not specifically refer to the singular and may also include the plural. The terms "first," "second," and similar terms used in this disclosure do not indicate any order, quantity, or importance, but are merely used to distinguish different components. Similarly, words such as "comprising" or "including" mean that the element or object preceding the word covers the element or object listed after the word and its equivalents, without excluding other elements or objects. Words such as "connected" or "linked" are not limited to physical or mechanical connections, but may include electrical connections, whether direct or indirect.

[0033] Figures 1 to 5 An embodiment of the underground diaphragm wall encroachment safety treatment method of the present invention is shown, which specifically includes the following steps:

[0034] S1: While excavating the foundation pit, monitor the encroachment data of the diaphragm wall 1 to determine the location of the non-encroachment section 11 and the encroachment section 12 of the diaphragm wall;

[0035] S2: While the foundation pit is being excavated, a waler 7 is erected on the continuous wall encroachment section 12, and a support beam 6 is erected on the waler 7;

[0036] S3: After the foundation pit is excavated, the bottom plate 33 of the encroaching section structure slab group 3 is constructed first, and then the non-encroaching section structure slab group 2 connected to the non-encroaching section 11 of the diaphragm wall is constructed. The encroaching section structure slab group 3 includes the bottom plate 33, the middle plate 32, and the top plate 31 of the encroaching section structure located at the bottom, middle, and top of the encroaching section 12 of the diaphragm wall, respectively. The non-encroaching section structure slab group 2 includes the bottom plate 23, the middle plate 22, and the top plate 21 of the non-encroaching section structure located at the bottom, middle, and top of the non-encroaching section 11 of the diaphragm wall, respectively. The non-encroaching section structure slab group 2 and the encroaching section structure slab group 3 play the role of supporting the foundation pit and bearing the load.

[0037] S4: Construct reinforcing piles 5 on the side of the continuous wall encroachment section 12 away from the foundation pit;

[0038] S5: The encroaching wall of the continuous wall encroaching section 12 is gradually removed from bottom to top, and the waler 7 and support beam 6 are gradually removed as the removal progresses. The middle slab 32 and the top slab 31 of the encroaching section structure are then poured in sequence.

[0039] During the excavation phase of the foundation pit, the encroachment of the diaphragm wall 1 is inferred from monitoring and measurement data to determine the location of the encroachment section 12. As excavation progresses, walers 7 and support beams 6 are installed on the encroachment section 12 as reinforcement measures, supporting the foundation pit and ensuring that the encroaching wall section 12 does not collapse during excavation. After the foundation pit excavation is completed, the encroachment section structural base slab 33 and the non-encroachment section structural slab assembly 2 are constructed to connect the diaphragm wall 1, which is beneficial to the stability of the standard diaphragm walls 11 on both sides of the encroachment section 12. Construction is carried out after the encroachment section 12. Reinforcing piles 5 are used to bear the soil pressure, ensuring that the reinforcing piles 5 can bear the remaining soil pressure after the encroaching wall of the continuous wall encroaching section 12 is removed, thus improving the stability of the foundation pit. The wall of the encroaching part of the continuous wall encroaching section 12 is gradually removed from bottom to top, and the walers 7 and support beams 6 are gradually removed as the removal progresses. The encroaching section structural middle plate 32 and the encroaching section structural top plate 31 of the encroaching section structural slab group 3 are poured in sequence, ensuring the continuity of the construction process. Moreover, the construction work of other standard section continuous walls 11 can still be carried out during the treatment of the encroaching section 12 of the continuous wall, without affecting the overall construction period.

[0040] In this embodiment, in step S2: at least one waler 7 is provided between the bottom slab 33 and the middle slab 32 of the encroaching section structure, and at least one waler 7 is provided between the middle slab 32 and the top slab 31 of the encroaching section structure. As a preferred embodiment, the diaphragm wall 1 is constructed using C40 grade concrete, and each diaphragm wall 1 has a width of 6m. In this embodiment, the encroaching section 12 consists of two adjacent walls (this embodiment uses this example; the actual construction process may vary), with a total width of 12m. The waler 7 applied to the encroachment section 12 of the continuous wall is 18m long and extends 3m from each side of the encroachment continuous wall 12. This not only improves the integrity of the two adjacent wall sections, but also ensures that the soil pressure after the encroachment section 12 of the continuous wall is fully transferred to the waler 7 and then to the supporting beam 6, further improving the overall stability of the encroachment section 12 of the continuous wall in the height direction. As a preferred embodiment, the diameter of the reinforcing pile 5 is 1m, the embedment depth is 6m, and the adjacent reinforcing piles 5 are arranged at a spacing of 1.4m. 24 steel bars of grade HRB600 and diameter of 28mm are used.

[0041] In this embodiment, in step S2: filling the gap between the waler 7 and the continuous wall encroachment section 12 with concrete 8 is more conducive to the transmission of earth pressure to the support beam 6 through the waler 7.

[0042] In this embodiment, in step S2: the concrete 8 is early-strength concrete, and the strength grade of the concrete 8 is greater than that of the concrete used in the underground continuous wall 1, so that the concrete 8 can reach the strength requirements in an early stage, which can improve the construction speed.

[0043] In this embodiment, a hole 4 is provided between the encroaching section structural slab group 3 and the encroaching part of the continuous wall encroaching section 12. The size of the hole 4 is determined according to the encroaching width and the actual construction. The transverse steel bars 43 in the encroaching section structural slab group 3, which are parallel to the length direction of the underground continuous wall 1, have sufficient lap length reserved on both sides of the hole 4. The longitudinal steel bars 44 in the encroaching section structural slab group 3, which are perpendicular to the length direction of the underground continuous wall 1, have mechanical joints 441 reserved at the edge of the hole 4. This facilitates the connection of the transverse steel bars 43 and the longitudinal steel bars 44 after the encroaching wall of the continuous wall encroaching section 12 is removed, ensuring the integrity of the encroaching section structural slab group 3 and preventing gaps between the encroaching section structural slab group 3 and the continuous wall encroaching section 12 after the encroaching wall is removed, thereby improving the structural strength of the encroaching section structural slab group 3.

[0044] In this embodiment, a waterproof layer 42 is provided on the side of the hole 4, which can prevent the transverse steel bars 43 and the longitudinal steel bars 44 from being corroded and reducing their tensile and compressive strength, and ensure the structural strength of the encroaching section structural slab group 3 during construction. As a preferred embodiment, the waterproof layer 42 is laid from the pre-reserved construction hole in the encroaching section structural bottom slab 33, which facilitates the later overlapping of the transverse steel bars 43 and the longitudinal steel bars 44. The overlap width of the waterproof layer 33 is 300mm, and the reserved overlap length of the transverse steel bars 43 is 500mm.

[0045] In this embodiment, a top brace 41 is provided in the hole 4 to connect the continuous wall encroachment section 12 and the encroachment section structural plate group 23. As a preferred embodiment, the top brace 41 is located in the upper area of ​​the hole. The top brace 41 can better support the continuous wall encroachment section 12 when the hole of the encroachment section structural plate group 3 is not poured, and can also avoid stress concentration in the encroachment section structural plate group 3 and damage caused by it.

[0046] In this embodiment, the detailed steps in step S5 are as follows:

[0047] a) First, remove the encroaching wall of the continuous wall encroaching section 12 located between the bottom slab 33 and the middle slab 32 of the encroaching section structure. Then, remove the waler 7 and support beam 6 located in this section. Next, remove the top bracing 41 and waterproof layer 42 on the bottom slab 33 of the encroaching section structure, connect the transverse steel bars 43 and the longitudinal steel bars 44, and finally pour concrete 8 into the hole 4 of the bottom slab 33 of the encroaching section structure.

[0048] b) After the predetermined strength is reached, remove the encroaching wall of the continuous wall encroaching section 12 between the middle slab 32 and the top slab 31 of the encroaching section structure. Then, remove the walers 7 and support beams 6 located in this section. Next, remove the top bracing 41 on the middle slab 32 of the encroaching section structure, connect the transverse steel bars 43 and the longitudinal steel bars 44, and finally pour concrete 8 into the holes 4 of the middle slab 32 of the structure.

[0049] c) Pour the top slab of the encroachment section structure 31.

[0050] The above steps ensure that a supporting structure is always in place to support the encroaching section 12 of the continuous wall during the removal of the encroaching wall, thus guaranteeing the overall stability of the foundation pit and preventing the collapse of the encroaching section 12 or even the foundation pit due to insufficient support. Immediately after the encroaching wall is removed, the holes 4 in the encroaching section structural slab group 3 are poured, allowing the encroaching section structural slab group 3 to fully exert its supporting capacity and take over the work of the supporting structure, ensuring the safety of the construction work. Furthermore, the construction work of the encroaching section 12 of the continuous wall and the encroaching section structural slab group 3 does not occupy additional space resources, and the relevant construction work of the standard continuous wall 11 can be carried out without delaying the overall construction period.

[0051] In this embodiment, the waler 7, the support beam 6, and the top brace 41 are all steel components, which have the advantages of being lightweight and having high strength. As a preferred embodiment, the top brace 41 is a 36C I-beam, and adjacent I-beams are arranged in the hole 4 with a spacing of 1.5m.

[0052] While the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the invention. Any person skilled in the art can make many possible variations and modifications to the technical solutions of the present invention, or modify them into equivalent embodiments, without departing from the scope of the present invention. Therefore, any simple modifications, equivalent changes, and modifications made to the above embodiments based on the technical essence of the present invention, without departing from the scope of the present invention, should fall within the protection scope of the present invention.

Claims

1. A method for handling the encroachment safety of underground diaphragm walls, characterized in that: Specifically, the steps include the following: S1: While excavating the foundation pit, monitor the encroachment data of the underground continuous wall (1) to determine the location of the non-encroachment section (11) and the encroachment section (12) of the continuous wall; S2: While the foundation pit is being excavated, a waler (7) is erected on the continuous wall encroachment section (12), and a support beam (6) is erected on the waler (7). S3: After the foundation pit excavation is completed, the bottom plate (33) of the encroaching section structure slab group (3) is constructed first, and then the non-encroaching section structure slab group (2) connected to the non-encroaching section (11) of the continuous wall is constructed. The encroaching section structure slab group (3) includes the bottom plate (33), the middle plate (32), and the top plate (31) of the encroaching section structure located at the bottom, middle, and top of the encroaching section (12) of the continuous wall, respectively. The non-encroaching section structure slab group (2) includes the bottom plate (23), the middle plate (22), and the top plate (21) of the non-encroaching section structure located at the bottom, middle, and top of the non-encroaching section (11) of the continuous wall, respectively. The non-encroaching section structure slab group (2) and the encroaching section structure slab group (3) are constructed together. Group (3) serves to support the foundation pit and bear the load; a hole (4) is provided between the encroaching section structural plate group (3) and the encroaching part of the continuous wall encroaching section (12); the transverse steel bars (43) in the encroaching section structural plate group (3) parallel to the length direction of the underground continuous wall (1) have sufficient lap length reserved on both sides of the hole (4); the longitudinal steel bars (44) in the encroaching section structural plate group (3) perpendicular to the length direction of the underground continuous wall (1) have mechanical joints (441) reserved at the edge of the hole (4); a waterproof layer (42) is provided on the side of the hole (4); a top brace (41) is provided in the hole (4) to connect the continuous wall encroaching section (12) and the encroaching section structural plate group (3). S4: Construct reinforcing piles (5) on the side of the continuous wall encroachment section (12) away from the foundation pit; S5: The encroaching wall of the continuous wall encroaching section (12) is gradually removed from bottom to top, and the waler (7) and the support beam (6) are gradually removed as the removal progresses. The middle slab (32) and the top slab (31) of the encroaching section structure are poured in sequence, including: a) First, the encroaching wall of the continuous wall encroaching section (12) located between the bottom slab (33) and the middle slab (32) of the encroaching section structure is removed. Then, the waler (7) and the support beam (6) located in this section are removed. Next, the top bracing (41) and the waterproof layer (42) on the bottom slab (33) of the encroaching section structure are removed. The transverse steel bar (43) and the longitudinal steel bar (44) are connected. Finally, concrete (8) is poured into the hole (4) of the bottom plate (33) of the encroaching section structure; b) the middle plate (32) of the encroaching section structure is poured, and after reaching the predetermined strength, the encroaching wall of the continuous wall encroaching section (12) between the middle plate (32) and the top plate (31) of the encroaching section structure is removed, and then the waler (7) and the support beam (6) located in this section are removed. Then the top bracing (41) on the middle plate (32) of the encroaching section structure is removed, and the transverse steel bar (43) and the longitudinal steel bar (44) are connected. Finally, concrete (8) is poured into the hole (4) of the middle plate (32) of the encroaching section structure; c) the top plate (31) of the encroaching section structure is poured.

2. The method for handling the encroachment safety of diaphragm walls according to claim 1, characterized in that: In step S2: at least one waler (7) is provided between the bottom plate (33) of the encroachment section structure and the middle plate (32) of the encroachment section structure, and at least one waler (7) is provided between the middle plate (32) of the encroachment section structure and the top plate (31) of the encroachment section structure.

3. The method for handling the encroachment safety of diaphragm walls according to claim 1, characterized in that: In step S2: concrete (8) is filled into the gap between the waler (7) and the continuous wall encroachment section (12).

4. The method for handling the encroachment safety of diaphragm walls according to claim 3, characterized in that: In step S2: the concrete (8) is early-strength concrete, and the strength grade of the concrete (8) is greater than the strength grade of the concrete used in the underground continuous wall (1).

5. The method for safe treatment of encroachment on underground diaphragm walls according to any one of claims 1 to 4, characterized in that: Both the waler (7) and the support beam (6) are steel components.

6. The method for handling the encroachment safety of diaphragm walls according to claim 1, characterized in that: The top bracing (41) is a steel component.

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