Underwater foundation pit construction method and underwater foundation pit structure

Abstract

The invention discloses a construction method of an underwater foundation pit and an underwater foundation pit structure. The construction method comprises the steps that a continuous wall around a foundation pit is constructed, and the foundation pit is excavated; the bottom of the foundation pit comprises a lower concrete bottom sealing layer and an upper concrete bottom sealing layer; concrete is poured into the lower concrete bottom sealing layer; the profile steel is hoisted to the shear-resistant groove of the continuous wall in the upper concrete bottom sealing layer, and the profile steel is fixed in the shear-resistant groove of the continuous wall; and concrete is poured into the upper concrete bottom sealing layer, so that the concrete in the upper concrete bottom sealing layer comprises the profile steel, and the concrete at the bottom of the foundation pit, the profile steel and the continuous wall form an underwater bottom sealing structure. According to the technical scheme, the thickness of the bottom sealing concrete can be effectively reduced, so that the underwater excavation depth of the foundation pit is reduced, and the construction safety of the foundation pit is guaranteed. And moreover, the structure is easy to operate, the construction process is simple, and divers do not need to conduct complex steel bar binding operation in the foundation pit under the underground water.

Description

Technical Field

[0001] The present application relates to the field of construction technology, and in particular to a construction method and an underwater foundation pit structure. Background Art

[0002] Constrained by the existing subway stations, sections and other underground structures, new underground rail transit projects in urban areas have entered the deep-buried stage. In the deep, water-rich gravel strata without obvious impermeable layers and in an environment without large-scale drainage conditions, how to deal with groundwater has become a key difficulty in the smooth implementation of the project.

[0003] Under the condition of open excavation, conventional dry excavation can be used for foundation pits above the groundwater level, and underwater excavation can be used for foundation pits below the groundwater level. The depth of underwater excavation of the foundation pit is affected not only by the depth of the structural bottom plate, but also by the thickness of the bottom concrete. In the prior art, in order to ensure the stability of the structure, very thick bottom concrete is usually used, which increases the depth of the foundation pit, the difficulty of construction and the safety risk. If thick bottom concrete is not used, the stability of the structure will be affected.

[0004] Therefore, how to reduce the thickness of the bottom sealing concrete while ensuring the stability of the foundation pit structure has become a problem that needs to be solved in this field. Summary of the invention

[0005] In view of this, in a first aspect, the present application proposes a construction method for an underwater foundation pit, wherein the bottom of the foundation pit is located below the groundwater level, and the method comprises:

[0006] Constructing a continuous wall around the foundation pit and excavating the foundation pit; the bottom of the foundation pit includes a lower concrete sealing layer and an upper concrete sealing layer;

[0007] pouring concrete in the lower concrete sealing layer;

[0008] Hoisting the steel section to the shear groove of the continuous wall in the upper concrete sealing layer, and fixing the steel section in the shear groove of the continuous wall;

[0009] Concrete is poured in the upper concrete sealing layer so that the concrete in the upper concrete sealing layer includes the steel section, and the concrete at the bottom of the foundation pit, the steel section and the continuous wall form an underwater sealing structure.

[0010] Preferably, the construction of the continuous wall and excavation of the foundation pit includes:

[0011] Constructing the continuous wall from the ground downwards;

[0012] A foundation pit is excavated in the continuous wall to the groundwater level, and after an internal support structure is erected above the groundwater level, the foundation pit is further excavated below the groundwater level.

[0013] Preferably, before hoisting the steel section to the shear groove of the continuous wall in the upper concrete sealing layer, the method further comprises:

[0014] A compartment wall is constructed at the bottom of the foundation pit, and the top of the compartment wall is flush with the top of the upper concrete sealing layer.

[0015] Further preferably, the compartment wall comprises: a shear groove corresponding to the shear groove of the continuous wall; and the fixing of the steel section comprises:

[0016] The steel sections are fixed in the shear grooves of the compartment walls and the continuous wall respectively.

[0017] Further preferably, the continuous wall and the compartment wall both include: embedded steel plates, and the steel sections are fixed in the shear grooves of the compartment wall and the continuous wall respectively, including:

[0018] The steel sections and the embedded steel plates of the compartment walls, as well as the steel sections and the embedded steel plates of the continuous walls are welded respectively in the shear grooves of the compartment walls and the continuous walls.

[0019] Further preferably, after pouring concrete in the upper concrete sealing layer, the method further comprises:

[0020] Pumping out the groundwater in the foundation pit;

[0021] Construct permanent structure in the foundation pit after drainage.

[0022] Further preferably, the construction of a permanent structure in the foundation pit after drainage comprises:

[0023] The inner support structure is used to construct a permanent structure in the foundation pit after drainage.

[0024] In a second aspect, the present application further provides an underwater foundation pit structure, which is constructed using the underwater foundation pit construction method as described in the first aspect, and includes: steel sections, a continuous wall arranged around the foundation pit, and a bottom sealing concrete arranged at the bottom of the foundation pit;

[0025] The continuous wall comprises a shear groove at the connection with the bottom cover concrete;

[0026] The steel section is fixed in the shear groove, so that the bottom sealing concrete includes the steel section, and the concrete at the bottom of the foundation pit, the steel section and the continuous wall form an underwater bottom sealing structure.

[0027] Preferably, the foundation pit structure further comprises: compartment walls;

[0028] The compartment wall is arranged at the bottom of the foundation pit, and the top thereof is flush with the top of the bottom concrete seal;

[0029] The compartment wall includes a shear groove corresponding to the shear groove of the continuous wall, and the steel sections are respectively fixed in the shear grooves of the compartment wall and the continuous wall.

[0030] Further preferred:

[0031] The continuous wall and the compartment wall both include embedded steel plates;

[0032] The steel sections and the embedded steel plates of the compartment walls, as well as the steel sections and the embedded steel plates of the continuous walls are welded respectively in the shear grooves of the compartment walls and the continuous walls.

[0033] The present application provides a method for constructing an underwater foundation pit. In the process of underwater bottom sealing, a steel section fixed to a continuous wall is added to the bottom sealing concrete, so that the bottom sealing concrete, the steel section and the continuous wall at the bottom of the foundation pit together constitute a stable underwater bottom sealing structure. The underwater bottom sealing concrete structure with steel sections arranged inside has better system integrity and stronger bending resistance, and can effectively reduce the thickness of the bottom sealing concrete, thereby reducing the underwater excavation depth of the foundation pit and ensuring the safety of the foundation pit construction. In addition, the present application is easy to operate and has a simple construction process, and there is no need for divers to perform complex steel bar bundling operations in the underground foundation pit.

[0034] Other features and advantages of the present application will be described in detail in the subsequent detailed description. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] The accompanying drawings constituting a part of the present application are used to provide a further understanding of the present application, and the schematic embodiments of the present application and their descriptions are used to explain the present application. In the accompanying drawings:

[0036] Figure 1 A schematic diagram of a construction method for an underwater foundation pit according to a preferred embodiment of the present application;

[0037] Figure 2 This is a schematic structural diagram of an underwater foundation pit structure according to a preferred embodiment of the present application;

[0038] Figure 3 This is a schematic structural diagram of the steel section and shear groove connection node of the preferred embodiment of the present application.

[0039] Figure numbers: 1- continuous wall; 2- compartment wall; 3- internal support structure; 4- bottom sealing concrete; 5- shear groove; 6- steel section; 7- groundwater level; 8- permanent structure. DETAILED DESCRIPTION

[0040] The technical solution of the present application will be described in detail below with reference to the accompanying drawings and in combination with the implementation modes.

[0041] In the first aspect, the construction method of the underwater foundation pit in the present application is as follows: Figure 2 As shown in FIG. 1 , part of the foundation pit is above the groundwater level, and the other part is below the groundwater level, that is, the bottom of the foundation pit is below the groundwater level. This application proposes a construction method for an underwater foundation pit that is filled with groundwater to form a stable foundation pit structure. Figure 1-3 As shown, the method includes steps 110-160:

[0042] Step 110, constructing a continuous wall around the foundation pit and excavating the foundation pit;

[0043] Specifically, the continuous wall can be understood as a continuous reinforced concrete wall built underground, which can be used as a water interception, anti-seepage, load-bearing, and water-retaining structure. In a specific embodiment, the method of constructing the continuous wall can be specifically as follows: using a trenching machine on the ground, along the peripheral axis of the deep excavation project, two narrow and long deep trenches are dug, and after the trenches are cleaned, a steel cage is suspended in the trenches, and then underwater concrete is poured using a conduit method to build a unit trench section. Repeat the above steps section by section to construct a continuous wall around the foundation pit.

[0044] When excavating the foundation pit, the continuous wall is used as the boundary of the foundation pit, and excavation is carried out from the ground to the underground. Due to the different geological structure characteristics above and below the ground water level, different foundation pit excavation modes can be adopted on both sides of the ground water level. Above the ground water level, the ordinary deep excavation method is used to excavate the foundation pit inside the continuous wall to the groundwater level. At this time, it is necessary to erect an internal support structure above the groundwater level, and then continue to excavate the foundation pit below the groundwater level using the underwater excavation method to the required depth. Among them, the internal support structure, as a temporary structure, can provide a structure above the ground water level to support the excavated foundation pit from collapsing, and the construction personnel can use the internal support structure as a landing point for subsequent construction.

[0045] Step 120, pouring concrete in the lower concrete sealing layer;

[0046] Specifically, after the foundation pit is dug to the required depth, the bottom of the foundation pit needs to be sealed with concrete. The concrete sealing layer in the present application includes two layers, that is, the bottom of the foundation pit includes a lower concrete sealing layer and an upper concrete sealing layer. The lower concrete sealing layer and the upper concrete sealing layer are bounded by the required fixed steel sections, that is, the shear groove of the continuous wall. Below the steel section is the lower concrete sealing layer, and the bottom surface of the lower concrete sealing layer is the bottommost surface of the foundation pit. Above the steel section is the upper concrete sealing layer, and the top surface height of the upper concrete sealing layer is the design elevation.

[0047] When pouring the concrete of the lower concrete sealing layer, it is necessary to pour it to the top of the shear groove to reserve space for fixing the steel section.

[0048] Step 130, hoisting the steel section to the shear groove of the continuous wall in the upper concrete sealing layer, and fixing the steel section in the shear groove of the continuous wall;

[0049] Specifically, after the concrete in the lower concrete sealing layer reaches a certain strength, the steel section is hoisted to the shear groove of the continuous wall and welded to the embedded steel plate in the continuous wall to fix the steel section in the shear groove of the continuous wall. This process can also be understood as adding a steel section fixed to the continuous wall on the concrete in the lower concrete sealing layer.

[0050] Furthermore, in order to increase the anti-floating, support and structural stability of the project during construction, the present application also constructs a compartment wall, that is, an anti-pullout wall, at the bottom of the foundation pit and in the middle of the two continuous walls. The top of the compartment wall is flush with the top of the upper concrete sealing layer. Moreover, the compartment wall, like the continuous wall, also includes a shear groove and an embedded steel plate, and the position of the shear groove of the compartment wall corresponds to the position of the shear groove of the continuous wall. The steel section is divided into two parts by the compartment wall. In the shear grooves of the compartment wall and the continuous wall, the steel section and the embedded steel plate of the compartment wall, as well as the steel section and the embedded steel plate of the continuous wall are welded respectively to fix the steel section in the shear grooves of the compartment wall and the continuous wall respectively.

[0051] Step 140: pouring concrete in the upper concrete sealing layer, so that the concrete in the upper concrete sealing layer includes steel sections, and the concrete, steel sections and continuous wall at the bottom of the foundation pit form an underwater sealing structure;

[0052] Specifically, after the steel is hoisted and fixed, concrete is poured in the upper concrete sealing layer to the designed elevation. At this time, the concrete in the upper concrete sealing layer includes the steel, and the concrete, steel and continuous wall at the bottom of the entire foundation pit together constitute the underwater sealing structure.

[0053] In the present application, the underwater bottom seal concrete structure with steel sections arranged inside has better system integrity and stronger bending resistance, which can effectively reduce the thickness of the bottom seal concrete, thereby reducing the underwater excavation depth of the foundation pit and ensuring the safety of the foundation pit construction.

[0054] After the concrete sealing layer is formed, a stable bottom structure of the foundation pit can be formed, and the groundwater in the foundation pit can be pumped out on the bottom structure, that is, steps 150-160 are executed.

[0055] Step 150, pumping out the groundwater in the foundation pit;

[0056] Specifically, a concrete bottom seal is used as the bottom structure of the trip, and groundwater in the foundation pit is pumped out to form a water-free space in the foundation pit.

[0057] Step 160, constructing a permanent structure in the foundation pit after drainage;

[0058] Specifically, the internal support structure is used to construct a permanent structure from bottom to top in the foundation pit after the pumping. After the permanent structure is completed, the internal support structure can be removed. The permanent structure can be understood as a building component that is used to exist for a long time, bear and transfer loads, meet specific functional requirements, and is not easily removed or replaced, including foundations, load-bearing walls, beams, columns and other structures.

[0059] The present application provides a method for constructing an underwater foundation pit. In the process of underwater bottom sealing, a steel section fixed to a continuous wall is added to the bottom sealing concrete, so that the bottom sealing concrete, the steel section and the continuous wall at the bottom of the foundation pit together constitute a stable underwater bottom sealing structure. The underwater bottom sealing concrete structure with steel sections arranged inside has better system integrity and stronger bending resistance, and can effectively reduce the thickness of the bottom sealing concrete, thereby reducing the underwater excavation depth of the foundation pit and ensuring the safety of the foundation pit construction. In addition, the present application is easy to operate and has a simple construction process, and there is no need for divers to perform complex steel bar bundling operations in the underground foundation pit.

[0060] In a second aspect, the present application also provides an underwater foundation pit structure, which is constructed using the underwater foundation pit construction method of the first aspect, such as Figure 2-3 As shown, the structure includes: steel 6, continuous wall 1 arranged around the foundation pit, and bottom cover concrete 4 arranged at the bottom of the foundation pit. The continuous wall 1 includes a shear groove 5 at the connection with the bottom cover concrete 4. The steel 6 is fixed in the shear groove 5 of the continuous wall 1, so that the bottom cover concrete 4 includes the steel 6, and the bottom cover concrete 4, the steel 6 and the continuous wall 1 at the bottom of the foundation pit constitute an underwater bottom cover structure.

[0061] In addition, the foundation pit structure of the present application further includes: a compartment wall 2. The compartment wall 2 is arranged at the bottom of the foundation pit, and the top is flush with the top of the bottom concrete seal 4. The compartment wall 2 includes a shear groove 5 corresponding to the shear groove 5 of the continuous wall 1, and the steel section 1 is fixed in the shear groove 5 of the compartment wall 2 and the continuous wall 1 respectively.

[0062] In addition, both the continuous wall 1 and the compartment wall 2 include embedded steel plates (not shown). In the shear grooves of the compartment wall 2 and the continuous wall 1, the steel section 6 and the embedded steel plates of the compartment wall 2, and the steel section 6 and the embedded steel plates of the continuous wall 1 are welded respectively.

[0063] The foundation pit above the groundwater level 7 also includes an internal support structure 3, and the internal support structure 3 can be used to construct a permanent structure 8 from bottom to top in the foundation pit. After the permanent structure 8 is constructed, the internal support structure 3 can be removed.

[0064] The other preferred embodiments, technical problems that can be solved and technical effects that can be achieved in the second aspect of the present application are the same as those in the first aspect and will not be elaborated here.

[0065] The preferred embodiments of the present application are described in detail above; however, the present application is not limited to the specific details in the above embodiments. Within the technical concept of the present application, a variety of simple modifications can be made to the technical solution of the present application, and these simple modifications all fall within the protection scope of the present application.

[0066] It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any suitable manner without contradiction. In order to avoid unnecessary repetition, this application will not further describe various possible combinations.

[0067] In addition, the various implementation modes of the present application may be arbitrarily combined, and as long as they do not violate the concept of the present application, they should also be regarded as the contents disclosed by the present invention.

Claims

1. A method for constructing an underwater foundation pit, characterized in that: The bottom of the foundation pit is below the groundwater level, and the method comprises: Constructing a continuous wall around the foundation pit and excavating the foundation pit; the bottom of the foundation pit includes a lower concrete sealing layer and an upper concrete sealing layer; pouring concrete in the lower concrete sealing layer; Hoisting the steel section to the shear groove of the continuous wall in the upper concrete sealing layer, and fixing the steel section in the shear groove of the continuous wall; Concrete is poured in the upper concrete sealing layer so that the concrete in the upper concrete sealing layer includes the steel section, and the concrete at the bottom of the foundation pit, the steel section and the continuous wall form an underwater sealing structure.

2. The construction method according to claim 1, characterized in that: The construction of the continuous wall and excavation of the foundation pit includes: Constructing the continuous wall from the ground downwards; A foundation pit is excavated in the continuous wall to the groundwater level, and after an internal support structure is erected above the groundwater level, the foundation pit is further excavated below the groundwater level.

3. The construction method according to claim 1, characterized in that: Before hoisting the steel sections to the shear grooves of the continuous wall in the upper concrete sealing layer, the method further comprises: A compartment wall is constructed at the bottom of the foundation pit, and the top of the compartment wall is flush with the top of the upper concrete sealing layer.

4. The construction method according to claim 3, characterized in that: The compartment wall comprises: a shear groove corresponding to the shear groove of the continuous wall; the fixing of the steel section comprises: The steel sections are fixed in the shear grooves of the compartment walls and the continuous wall respectively.

5. The construction method according to claim 4, characterized in that: The continuous wall and the compartment wall both include: embedded steel plates, and the steel sections are fixed in the shear grooves of the compartment wall and the continuous wall respectively, including: The steel sections and the embedded steel plates of the compartment walls, as well as the steel sections and the embedded steel plates of the continuous walls are welded respectively in the shear grooves of the compartment walls and the continuous walls.

6. The construction method according to claim 2, characterized in that: After pouring concrete in the upper concrete sealing layer, the method further comprises: Pumping out the groundwater in the foundation pit; Construct permanent structure in the foundation pit after drainage.

7. The construction method according to claim 6, characterized in that: The permanent structure is constructed in the foundation pit after drainage, including: The inner support structure is used to construct a permanent structure in the foundation pit after drainage.

8. An underwater foundation pit structure, characterized in that: The structure is constructed using the underwater foundation pit construction method according to any one of claims 1 to 7, comprising: steel sections, a continuous wall arranged around the foundation pit, and bottom sealing concrete arranged at the bottom of the foundation pit; The continuous wall comprises a shear groove at the connection with the bottom cover concrete; The steel section is fixed in the shear groove, so that the bottom sealing concrete includes the steel section, and the concrete at the bottom of the foundation pit, the steel section and the continuous wall form an underwater bottom sealing structure.

9. The foundation pit structure according to claim 8, characterized in that: The foundation pit structure also includes: compartment walls; The compartment wall is arranged at the bottom of the foundation pit, and the top thereof is flush with the top of the bottom concrete seal; The compartment wall includes a shear groove corresponding to the shear groove of the continuous wall, and the steel sections are respectively fixed in the shear grooves of the compartment wall and the continuous wall.

10. The foundation pit structure according to claim 9, characterized in that: The continuous wall and the compartment wall both include embedded steel plates; The steel sections and the embedded steel plates of the compartment walls, as well as the steel sections and the embedded steel plates of the continuous walls are welded respectively in the shear grooves of the compartment walls and the continuous walls.

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