Underwater foundation pit excavation method

Abstract

The present invention discloses an underwater foundation pit excavation method, comprising: a first step of constructing an underground continuous wall within a soil body; a second step of excavating a foundation pit within the underground continuous wall without drainage; a third step of using a suspended support as a support for the foundation pit after the foundation pit is excavated to a certain depth, constructing a suspended support within the foundation pit and installing it on the underground continuous wall; a fourth step of continuing to excavate the foundation pit without drainage, rigidly connecting another suspended support above the top suspended support via a rigid connector, sinking the connected multiple suspended supports as a whole to predetermined positions within the foundation pit with groundwater and installing them on the underground continuous wall at the corresponding positions; a fifth step of repeating the fourth step until all suspended supports within the foundation pit are constructed, and then excavating the foundation pit without drainage to the bottom elevation of the foundation pit. The present invention can reduce the difficulty of constructing a foundation pit support system, has low construction costs, and avoids the effect of foundation pit drainage.

Description

Technical Field

[0001] The present invention relates to the technical field of construction engineering, and in particular to an underwater foundation pit excavation method. Background Art

[0002] Traditional excavation requires draining the pit before proceeding. Excavating a pit with abundant groundwater using traditional methods often results in high drainage and support costs, as well as significant difficulties in establishing a support system. Summary of the Invention

[0003] The purpose of the present invention is to provide an underwater foundation pit excavation method to solve the problems of difficulty in building a foundation pit support system, complicated foundation pit drainage procedures and high construction costs.

[0004] In order to achieve the above object, the present invention provides an underwater foundation pit excavation method, comprising:

[0005] The first step is to construct an underground continuous wall in the soil;

[0006] The second step is to excavate the foundation pit without drainage inside the underground continuous wall;

[0007] In the third step, after the foundation pit is excavated to a certain depth, a suspended support is used as the foundation pit support. The suspended support includes an I-beam and a foam body filled between the flanges of the I-beam. The foam body is distributed on both sides of the web of the I-beam. A suspended support is constructed in the foundation pit and installed on the underground continuous wall.

[0008] The fourth step is to continue excavating the foundation pit without drainage, rigidly connect a suspended support above the top suspended support through a rigid connector, sink the connected multiple suspended supports as a whole to the predetermined position in the foundation pit with groundwater, and install them on the underground continuous wall at the corresponding position;

[0009] Step 5: Repeat step 4 until all suspended supports in the foundation pit are constructed and excavated to the bottom elevation of the foundation pit without drainage.

[0010] Furthermore, the underwater foundation pit excavation method provided by the present invention casts a base plate at the bottom of the foundation pit after the foundation pit is excavated.

[0011] Furthermore, the underwater foundation pit excavation method provided by the present invention provides a track on the underground continuous wall, and each of the suspended supports slides down to a predetermined position of the underground continuous wall via the track.

[0012] Furthermore, in the underwater foundation pit excavation method provided by the present invention, end plates are provided at both ends of the I-beam, and the end plates are bolted to the rails.

[0013] Furthermore, in the underwater foundation pit excavation method provided by the present invention, the I-beam is replaced by H-beam.

[0014] Furthermore, in the underwater foundation pit excavation method provided by the present invention, the rigid connecting member is a steel section.

[0015] Furthermore, in the underwater foundation pit excavation method provided by the present invention, there are more than two suspended supports, each suspended support is arranged parallel to each other, and two adjacent suspended supports are connected by at least two vertically arranged rigid connectors.

[0016] Compared with the prior art, the underwater foundation pit excavation method provided by the present invention has the following beneficial effects:

[0017] First, the foundation pit can be excavated in the presence of water without the need for foundation pit drainage. The water pressure on both sides of the underground continuous wall is balanced, the thickness of the underground continuous wall and the number of supports required are reduced, and the overall construction cost is reduced. The problem of difficulty in draining foundation pits with particularly abundant groundwater can be avoided, and the need for construction procedures such as precipitation wells and drainage wells for foundation pit drainage is overcome. The construction procedures of foundation pit excavation are simplified, and the construction efficiency of foundation pit excavation is improved.

[0018] Secondly, the suspended support, composed of I-beams and foam, reduces its own weight and allows it to float in water. During the subsequent underwater excavation of the foundation pit, a further suspended support is gradually added above the topmost suspended support through connectors. The entire structure then sinks and shifts, allowing new supports to be constructed on the underground continuous wall within the foundation pit. This provides support during the underwater excavation process, resolving the difficulty associated with heavy support weight during underwater excavation and reducing the risk of foundation pit support construction.

[0019] Thirdly, multiple suspended supports are rigidly connected through rigid connectors to form a suspended support system. The suspended supports and their system can be suspended in the water in the foundation pit, and new supports are applied by sinking, which has the advantages of easy operation and low energy consumption. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figures 1 to 4 It is a schematic diagram of the elevation structure of the foundation pit excavation and the installation of suspended supports;

[0021] Figure 5 It is a schematic diagram of the cross-sectional structure of the suspended support;

[0022] Figure 6 This is a schematic diagram of the facade structure where the suspended support is displaced by sinking of the track;

[0023] As shown in the figure:

[0024] 1. Soil;

[0025] 2. Underground continuous wall;

[0026] 3. Foundation pit;

[0027] 4. Groundwater, 41. Groundwater level;

[0028] 5. Suspended support system, 50. Rigid connector, 51. Penultimate suspended support, 511. I-beam, 512. Foam, 52. Penultimate suspended support, 53. Penultimate suspended support;

[0029] 6. Bottom plate;

[0030] 7. Track. DETAILED DESCRIPTION

[0031] The present invention will be described in detail below with reference to the accompanying drawings. The advantages and features of the present invention will become more apparent from the following description. It should be noted that the drawings are all in a very simplified form and are not accurately scaled, and are only used to facilitate and clearly illustrate the embodiments of the present invention.

[0032] Please refer to Figures 1 to 5 The embodiment of the present invention provides an underwater foundation pit excavation method. For ease of understanding, the following is an illustration using three supports as an example. The foundation pit excavation method includes the following steps:

[0033] Step 701, please refer to Figure 1 , construct an underground continuous wall 2 in the soil 1.

[0034] Step 702, please refer to Figure 1 , a foundation pit 3 is excavated without drainage in the underground continuous wall 2. At this time, the excavated foundation pit 3 may have groundwater 4 gushing out, or may not have groundwater 4 gushing out.

[0035] Step 703, please refer to Figure 1 and Figure 5 After the foundation pit 3 is excavated to a certain depth, a suspended support 5 is used as the foundation pit support. A suspended support (ultimately the penultimate support 51) is constructed within the foundation pit 3 and installed on the underground continuous wall 2. The suspended support may include an I-beam 511 and a foam body 512 filled between the flanges of the I-beam 511. To improve the suspension effect and balance, the foam body 512 is distributed on both sides of the web of the I-beam 511. The I-beam 511 can be replaced by an H-beam. In this case, the penultimate support 51 is the first support within the foundation pit 3.

[0036] Step 704, please refer to Figure 2 and Figure 3, continue to excavate the foundation pit 3 without drainage, and rigidly connect a suspended support (that is, the penultimate support 52) ​​above the top suspended support (that is, the penultimate support 51) through a rigid connector 50, and connect the two connected suspended supports ( Figures 2 to 3 The support 51 and 52 in the figure are lowered as a whole to a predetermined position in the foundation pit 3 with groundwater 4 and installed on the underground continuous wall 2 at the corresponding position. At this time, the second-to-last support 52 becomes the first support in the foundation pit 3, and the first-to-last support 51 becomes the second support in the foundation pit 3.

[0037] Step 705, please refer to Figure 4 , repeat step 704, that is, rigidly connect a suspended support (that is, ultimately the third-to-last support 53) above the top suspended support (that is, ultimately the second-to-last support 52) ​​through a rigid connector 50, sink the entirety to a predetermined position in the foundation pit with groundwater 4 and set it on the underground continuous wall 2 at the corresponding position, until all suspended supports in the foundation pit 3 are constructed, and excavate to the bottom elevation of the foundation pit without drainage. At this time, the third-to-last support 53 is changed to the first support in the foundation pit 3, the second-to-last support 52 is changed to the second support in the foundation pit 3, and the first-to-last support 51 is changed to the third support in the foundation pit 3, and the groundwater level 41 may be higher than the first support. The structural composition of each suspended support is the same. It should be noted that the underwater foundation pit excavation method provided in the embodiment of the present invention is not limited to the working condition of three supports, and the number of supports can be adjusted according to the excavation depth of the foundation pit.

[0038] Please refer to Figure 4 In order to prevent deformation at the bottom of the foundation pit after excavation, the underwater foundation pit excavation method provided by the embodiment of the present invention casts a bottom plate 6 at the bottom of the foundation pit 3 after the foundation pit is excavated.

[0039] Please refer to Figure 6 In order to facilitate the overall sinking and displacement of the connected suspended support, the underwater foundation pit excavation method provided by the embodiment of the present invention can set a track 7 on the underground continuous wall 2, and each of the suspended supports slides down to the predetermined position of the underground continuous wall 2 through the track 7.

[0040] In order to realize the fixed setting of the suspended support on the underground continuous wall 2, the underwater foundation pit excavation method provided by the embodiment of the present invention can be provided with end plates at both ends of the I-beam 511, and the end plates are bolted to the track 7.

[0041] Please refer to Figure 4 In order to improve the rigid connection effect, in the underwater foundation pit excavation method provided by the embodiment of the present invention, the rigid connector 50 can be an I-beam, H-beam, Caogong or other steel or steel column.

[0042] Please refer to Figure 4 In order to improve the reliability of the connection between the suspended supports, an embodiment of the present invention provides an underwater foundation pit excavation method, in which there are more than two suspended supports, each suspended support is arranged parallel to each other, and two adjacent suspended supports are connected by at least two vertically arranged rigid connectors 50.

[0043] The underwater foundation pit excavation method provided by the embodiment of the present invention is that the foundation pit can be excavated in the presence of water without the need for foundation pit drainage, so that the water pressure on both sides of the underground continuous wall 2 is balanced, the thickness of the underground continuous wall 2 and the demand for the number of supports are reduced, and the overall construction cost is reduced. The problem of difficulty in draining the foundation pit with particularly abundant groundwater 4 can be avoided, and the need for construction processes such as dewatering wells and drainage wells for foundation pit drainage is overcome, the construction process of foundation pit excavation is simplified, and the construction efficiency of foundation pit excavation is improved.

[0044] In the underwater foundation pit excavation method provided by an embodiment of the present invention, a suspended support is composed of an I-beam 511 and a foam body 512, which reduces the support's deadweight and enables it to float in water. During the subsequent underwater foundation pit excavation process, a suspended support is gradually added above the uppermost suspended support via connectors, and the entire support is lowered and shifted, thereby constructing a new support on the underground continuous wall 2 within the foundation pit. This provides support during the underwater foundation pit excavation process, solves the problem of difficulty in construction caused by the heavy deadweight of the support during underwater excavation, and reduces the danger of foundation pit support construction.

[0045] In the underwater foundation pit excavation method provided by an embodiment of the present invention, multiple suspended supports are rigidly connected by rigid connectors 50 to form a suspended support system. The suspended supports and their system can be suspended in the water in the foundation pit, and new supports are applied by sinking, which has the advantages of easy operation, high safety and low energy consumption.

[0046] The present invention is not limited to the specific embodiments described above. Obviously, the embodiments described above are only some embodiments of the embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention described, all other embodiments obtained by ordinary technicians in this field fall within the scope of protection of the present invention. Those skilled in the art can make other levels of modifications and changes to the present invention. In this way, if these modifications and changes of the present invention fall within the scope of the claims of the present invention, the present invention is also intended to include these changes and changes.

Claims

1. A method for underwater foundation pit excavation, characterized in that: include: The first step is to construct an underground continuous wall in the soil; The second step is to excavate the foundation pit without drainage inside the underground continuous wall; In the third step, after the foundation pit is excavated to a certain depth, a suspended support is used as the foundation pit support. The suspended support includes an I-beam and a foam body filled between the flanges of the I-beam. The foam body is distributed on both sides of the web of the I-beam. A suspended support is constructed in the foundation pit and installed on the underground continuous wall. The fourth step is to continue excavating the foundation pit without drainage, rigidly connect a suspended support above the top suspended support through a rigid connector, sink the connected multiple suspended supports as a whole to the predetermined position in the foundation pit with groundwater, and install them on the underground continuous wall at the corresponding position; Step 5: Repeat step 4 until all suspended supports in the foundation pit are constructed and excavated to the bottom elevation of the foundation pit without drainage.

2. The underwater foundation pit excavation method according to claim 1, characterized in that: After the foundation pit is excavated, the base plate is poured at the bottom of the foundation pit.

3. The underwater foundation pit excavation method according to claim 1, characterized in that: A track is arranged on the underground continuous wall, and each of the suspended supports slides down to a predetermined position of the underground continuous wall through the track.

4. The underwater foundation pit excavation method according to claim 3, characterized in that: End plates are provided at both ends of the I-beam, and the end plates are bolted to the rails.

5. The underwater foundation pit excavation method according to claim 1, characterized in that: The I-beam is replaced by H-beam.

6. The underwater foundation pit excavation method according to claim 1, characterized in that: The rigid connecting piece is steel.

7. The underwater foundation pit excavation method according to claim 1, characterized in that: There are more than two suspended supports, each suspended support is arranged parallel to each other, and two adjacent suspended supports are connected by at least two vertically arranged rigid connectors.

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