Construction method of river-related ultra-deep foundation pit

Abstract

The invention relates to the technical field of ultra-deep foundation pit construction, in particular to a construction method of a river-related ultra-deep foundation pit, a blocking wall is constructed in the range of an underground diaphragm wall, the blocking wall divides the ultra-deep foundation pit into a first-stage foundation pit and a second-stage foundation pit, and the first-stage foundation pit totally covers the flow path range of a river channel; a culvert pipe is arranged on the underground diaphragm wall corresponding to the second-stage foundation pit, the culvert pipe penetrates through a construction area of the second-stage foundation pit, one end of the culvert pipe is communicated with a river channel outside one side of the first-stage foundation pit, and the other end of the culvert pipe is communicated with a river channel outside the other side of the first-stage foundation pit. The culvert pipe forms a river diversion channel for avoiding the first-stage foundation pit; and the first-stage foundation pit is constructed in the state that the culvert pipe conducts river diversion. The method has the advantages that in-situ or ex-situ diversion of river water flow is realized, and normal flood discharge, water supply and ecological flow requirements of the river during construction of the ultra-deep foundation pit are guaranteed.

Description

Technical Field

[0001] This invention relates to the field of ultra-deep foundation pit construction technology, and in particular to a construction method for an ultra-deep foundation pit crossing a river. Background Technology

[0002] With the rapid development of cities, the construction of underground rail transit stations and underground highway tunnels is increasing. However, the water system and dense river network in southern my country make it easy for ultra-deep foundation pit construction of such underground projects to conflict with existing waterways. Currently, the mainstream technical measures in the industry to deal with this conflict are mainly open river relocation and river channel interruption. However, these measures have many drawbacks in practical applications, and better technical solutions are urgently needed to overcome the difficulties.

[0003] (1) The open river relocation technology, the core of which is to achieve water flow avoidance by "building a new alternative river channel + blocking the original river channel". Outside the impact range of the foundation pit construction, a new river channel is designed and excavated according to the water carrying capacity of the original river channel. After the river channel relocation is completed, the foundation pit construction is carried out. Its core principle is to avoid direct conflict between foundation pit construction and river flow by spatially shifting the location of the river channel. However, it has significant disadvantages such as high engineering cost, long construction period, significant ecological damage, and strong site constraints.

[0004] (2) River flow interruption technology: This technology creates a waterless environment for foundation pit construction by temporarily blocking the flow of river water. However, it still has drawbacks such as complete destruction of water flow, extremely high flood control risk, and significant impact on water quality.

[0005] In summary, existing technologies for relocating open rivers and cutting off river flow cannot effectively balance the construction needs of ultra-deep foundation pits with the protection of normal river functions, and have inherent defects such as high cost, long cycle, and great ecological and safety risks. Summary of the Invention

[0006] The purpose of this invention is to address the shortcomings of the prior art by providing a construction method for ultra-deep foundation pits across rivers. By pre-designing river culverts within the diaphragm wall, the method enables in-situ or out-of-situ diversion of river flow. This ensures the normal flood control, water supply, and ecological flow requirements of the river during the construction of the ultra-deep foundation pit, while strictly adhering to relevant regulations on water conservancy and ecological protection. Furthermore, the coordinated design of the diaphragm wall and culverts enhances the overall adaptability of the support system and reduces hydrological disturbances during construction. This provides a mature and reliable technical approach for ultra-deep foundation pit construction under similar complex hydrogeological conditions.

[0007] The objective of this invention is achieved through the following technical solutions: A construction method for an ultra-deep foundation pit crossing a river includes a diaphragm wall serving as the support structure for the ultra-deep foundation pit, wherein the flow path of the ultra-deep foundation pit interferes with the flow path of the river, i.e., the flow path of the river passes through the construction area of ​​the ultra-deep foundation pit, characterized in that: the construction method includes: Within the area of ​​the underground continuous wall, a sealing wall is constructed, which divides the ultra-deep foundation pit into a first-phase foundation pit and a second-phase foundation pit, wherein the first-phase foundation pit completely covers the flow path of the river channel; A culvert is installed on the underground continuous wall corresponding to the second-phase foundation pit. The culvert passes through the construction area of ​​the second-phase foundation pit. One end of the culvert is connected to a river channel outside one side of the first-phase foundation pit, and the other end is connected to a river channel outside the other side of the first-phase foundation pit. The culvert forms a river channel diversion channel that avoids the first-phase foundation pit. While the culvert is diverting water into the river, the construction of the first-phase foundation pit is carried out. After the first phase of foundation pit construction is completed, the culvert will be removed and the underground continuous wall corresponding to the second phase of foundation pit will be restored by grouting.

[0008] During the construction of the diaphragm wall, a pre-embedded steel ring is welded into the reinforcing cage inside. This pre-embedded steel ring becomes an opening in the diaphragm wall for connection between the diaphragm wall and the culvert. The culvert is then connected and fixed to the pre-embedded steel ring.

[0009] The culvert is divided into two turning pipe sections and one crossing pipe section. The two turning pipe sections are fixedly connected to the outside of the pre-embedded steel rings, and the two ends of the crossing pipe section are fixedly connected to the inside of the pre-embedded steel rings on both sides.

[0010] When the culvert is removed, the crossing pipe section will also serve as the steel support for the underground continuous wall corresponding to the second-phase foundation pit.

[0011] Grouting is performed on the crossing pipe section that also serves as a steel support to form a reinforced concrete support, or the crossing pipe section is used as a mold for the concrete support construction.

[0012] Construction of a reinforcing sidewall on the outer side of the diaphragm wall located at the opening location.

[0013] The advantages of this invention are: (1) Improve construction efficiency, eliminate redundant procedures such as river rerouting, reduce cross-interference, shorten the construction period of river-related construction compared with traditional methods, and ensure progress.

[0014] (2) Save construction costs, save large expenses such as temporary detours, reduce construction losses and hidden costs, and significantly reduce overall costs.

[0015] (3) Strengthen construction quality and structural safety, avoid hidden dangers such as leakage and deformation, restore the water-stopping properties of the ground wall support, and significantly reduce safety risks.

[0016] (4) Reduce ecological impact, ensure uninterrupted river flow, reduce pollution such as dust and noise, practice green construction, and improve environmental benefits.

[0017] (5) Fill the technological gap, build a replicable closed-loop method, solve traditional pain points, provide solutions for similar working conditions, and promote the upgrading of industry processes. Attached Figure Description

[0018] Figure 1 Construction steps of the present invention Figure I ; Figure 2 Construction steps of the present invention Figure II ; Figure 3 Construction steps of the present invention Figure III ; Figure 4 Construction steps of the present invention Figure IV ; Figure 5 Construction steps of the present invention Figure V ; Figure 6 This is a schematic diagram of the culvert opening in the underground continuous wall in this invention; Figure 7 This is a schematic diagram of the structure of the cut-off steel bar end at the edge of the culvert in this invention; Figure 8 This is a schematic diagram of the culvert repair hole in the underground continuous wall in this invention; Figure 9 This is a schematic cross-sectional view of the steel ring pre-embedded in the culvert in this invention; Figure 10 This is a plan view of the steel ring pre-embedded in the culvert in this invention; Figure 11 This is an enlarged view of the end of the pre-embedded steel ring in the culvert of the present invention; Figure 12 This is a detailed drawing of the steel plate and reinforcing bars of the culvert pre-embedded steel ring in this invention. Detailed Implementation

[0019] The features and other related features of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments, so as to facilitate understanding by those skilled in the art: like Figure 1-12 As shown in the figure, the markings represent: 1. River boundary line, 2. Diaphragm wall, 3. Road boundary line, 4. Sealing wall, 5. Phase I foundation pit area, 6. Phase II foundation pit area, 7. Bridge line, 8. Culvert, 9. Embedded steel ring, 10. Anchor bar, 11. Anchor bar, 12. Water-swellable waterstop strip, 13. Full-section grouting pipe, 14. X-direction reinforcing steel bar, 15. Y-direction reinforcing steel bar, 16. Reinforcing side wall, 17. Top slab reinforcing steel bar.

[0020] Example: Figures 1 to 12As shown, the construction method for ultra-deep foundation pits across rivers in this embodiment is used to resolve the spatial conflict between the construction of ultra-deep foundation pits and existing river channels.

[0021] Specifically, such as Figure 1 As shown, the support structure for the ultra-deep foundation pit in this embodiment is a diaphragm wall 2. The diaphragm wall 2 encloses the construction area of ​​the ultra-deep foundation pit, including a first-phase foundation pit area 5 and a second-phase foundation pit area 6, where the first-phase foundation pit area 5 is constructed before the second-phase foundation pit area 6. The first-phase foundation pit area 5 and the second-phase foundation pit 6 are separated by a sealing wall 4, the two ends of which are fixedly connected to the corresponding sides of the diaphragm wall 2.

[0022] like Figure 1 As shown, river boundary line 1 represents the boundary of the existing river at the location of the ultra-deep foundation pit. This existing river flows through area 5 of the first-phase foundation pit, creating a spatial conflict with area 5, but not with area 6 of the second-phase foundation pit. Road red line 3 represents the boundary of the existing road at the location of the ultra-deep foundation pit. Bridge line 7 represents the design boundary of the bridge to be constructed later.

[0023] The culvert-through-diaphragm wall structure in this embodiment includes several hollow culverts 8. Each culvert 8 passes through the diaphragm wall 2 of the second-phase foundation pit area 6. One end of each culvert 8 is connected to an existing river channel on one side of the first-phase foundation pit area 5, and the other end is connected to an existing river channel on the other side of the first-phase foundation pit area 5, thereby achieving river diversion and bypass. Figure 3 or Figure 4 As shown in the diagram, if the existing river channel runs through the first-phase foundation pit area 5 from north to south, then one end of the culvert 8 is connected to the river channel located outside the underground continuous wall on the north side of the first-phase foundation pit area 5, and the other end is connected to the river channel located outside the underground continuous wall on the south side of the first-phase foundation pit area 5. The interior of the culvert 8 forms a river channel, and the river water flows through the culvert 8 and passes through the second-phase foundation pit area 6, thus achieving the detour of the first-phase foundation pit area 5 and resolving the spatial conflict between the first-phase foundation pit area 5 and the existing river channel; at this time, the first-phase foundation pit area 5 can be constructed normally.

[0024] In this embodiment, as Figure 3 or Figure 4 As shown, the culvert 8 includes a turning pipe section located outside the diaphragm wall 2 and a crossing pipe section located inside the diaphragm wall 2 in the second-phase foundation pit area 6. The two sides of the crossing pipe section are connected to the turning pipe section to ensure the smooth flow of the river.

[0025] Combination Figures 6 to 12As shown, in this embodiment, the fixed connection between the culvert 8 and the diaphragm wall 2 is achieved by opening a hole in the diaphragm wall 2. Specifically, during the construction of the diaphragm wall 2, an opening matching the size and dimensions of the culvert 8 is reserved, and a pre-embedded steel ring 9 is embedded in the opening. The pre-embedded steel ring 9 is fixedly connected to the reinforcing steel bars in the diaphragm wall 2 to form an integral structure, thereby ensuring the structural strength and stability of the pre-embedded steel ring 9, which serves as the connection interface for the culvert 8.

[0026] Combination Figures 6 to 8 As shown, because there are openings in the diaphragm wall 2, X-direction reinforcing bars 14 (horizontal direction) and Y-direction reinforcing bars 15 (vertical direction) are installed inside the diaphragm wall 2. These X-direction reinforcing bars 14 and Y-direction reinforcing bars 15 are welded and fixed to the original reinforcing bars of the diaphragm wall 2 to form a whole, thereby reinforcing the structural strength at the opening location of the diaphragm wall 2 and avoiding structural strength loss due to the opening. Figure 7 As shown, when the upper and lower reinforcing bars located at the opening in the underground continuous wall 2 are cut off, the embedded steel ring 9 is welded to the cut upper and lower reinforcing bars to improve the structural strength and stability of the embedded steel ring 9.

[0027] Combination Figures 9 to 12 As shown, in this embodiment, the pre-embedded steel ring 9 has several radially evenly spaced and radiatingly welded anchor bars 10 and 11 on its outer circumferential side to improve the connection strength between the pre-embedded steel ring 9 and the underground continuous wall 2; the anchor bars 10 and 11 are arranged at intervals in the circumferential direction of the pre-embedded steel ring 9. Wherein, as... Figure 12 As shown, the anchor bar 10 is bent and inclined, and is partially welded to the pre-embedded steel ring 9 on both sides. Several anchor bars 11 include two sets of anchor bars arranged radially spaced along the pre-embedded steel ring 9, and one set of anchor bars arranged axially along the pre-embedded steel ring 9. The difference between anchor bars 10 and anchor bars 11 is that anchor bars 10 have a relatively small diameter and relatively short length, while anchor bars 11 have a relatively large diameter and relatively long length.

[0028] Combination Figure 9 and Figure 12 As shown, two rings of water-swellable sealing strips 12 are arranged axially at intervals around the pre-embedded steel ring 9 to ensure the water-stopping performance at the connection point between it and the underground continuous wall 2.

[0029] like Figure 9As shown, to further ensure the structural strength of the diaphragm wall 2, a reinforcing side wall 16 is installed on the outside of the opening in the diaphragm wall 2. This reinforcing side wall 16 is a concrete side wall, and during its construction, an opening matching the pre-embedded steel ring 9 is reserved. At the same time, to ensure the water-stopping performance between the diaphragm wall 2 and the reinforcing side wall 16, a water-swellable waterstop strip 12 is installed between the two.

[0030] like Figure 12 As shown, during the construction of the diaphragm wall 2, a full-section grouting pipe 13 is pre-installed; when the culvert 8 is completed and it is necessary to fill and seal the holes in the diaphragm wall 2, grouting is performed on the diaphragm wall 2 through the full-section grouting pipe 13. Figure 8 As shown, when sealing the holes in the underground continuous wall 2, the holes are welded together with the original reinforcement and the pre-embedded steel ring 9, and the corresponding top plate reinforcement 17 is added at the top plate location.

[0031] When using this embodiment, the following construction steps are included: 1) Construct a diaphragm wall 2 outside the river channel according to the river channel location. The diaphragm wall 2 is made of reinforced concrete. During the processing of the steel cage of the diaphragm wall 2, a pre-embedded steel ring 9 of matching size is precisely reserved at the crossing position of the pre-set culvert 8. The pre-embedded steel ring 9 is implemented simultaneously with the construction of the diaphragm wall 2.

[0032] In this embodiment, in order to ensure the smooth progress of subsequent river diversion, the design of the underground continuous wall 2 should incorporate monitoring data such as the river's flow rate and velocity to design a corresponding number of pre-embedded steel rings 9, so as to ensure that the number of culverts 8 connected later meets the requirements of river diversion.

[0033] 2) After the concrete pouring of the underground continuous wall 2 in the second-phase foundation pit area 6 outside the river channel is completed and the strength reaches the design strength, the prefabricated culvert 8 is hoisted to the construction area. The culvert 8 is made of steel pipe. The culvert 8 is connected to the pre-embedded steel ring 9 by flange connection or welding to form a complete river channel.

[0034] 3) After the culvert 8 in the second-phase foundation pit area 6 outside the river channel is connected, a water tightness test and water flow commissioning are carried out. After confirming that there is no leakage and the water flow is smooth, the river water is introduced into the culvert 8 for diversion. After the water flow stabilizes, the original river channel is closed and the construction of the remaining underground continuous wall 2 in the first-phase foundation pit area 5 within the river channel is carried out to avoid water flow interfering with the construction of the underground continuous wall 2.

[0035] In this embodiment, in order to ensure that the river water is introduced into the culvert 8 for diversion, any diversion or guiding device or component in the prior art can be used inside the river to change the local flow direction of the river, such as constructing a guide wall inside the river; thereby so that all the water in the river is introduced into the culvert 8 for diversion.

[0036] 4) After the construction of the underground continuous wall 2 in the first phase foundation pit area 5 within the river channel is completed, the foundation pit will be excavated in layers and sections according to the ultra-deep foundation pit excavation plan. During the excavation, the normal flow of river water will be continuously ensured through the culvert 8, and the inspection and maintenance of the culvert and the nodes penetrating the underground continuous wall will be strengthened at the same time.

[0037] 5) After the main structure of the first-phase foundation pit area 5 within the river channel is completed and the strength meets the standards, the river channel will be relocated to its original position. Once the water flow stabilizes, the temporarily erected culvert 8 will be dismantled. If the culvert size meets the subsequent diversion needs of other river channels, it can be recycled and transported to the next construction site for reuse, reducing material waste and project costs, while minimizing environmental impact and achieving resource recycling; during the dismantling process, avoid impacting the underground continuous wall.

[0038] 6) After the culvert 8 is removed, the opening formed by the reserved steel ring 9 of the diaphragm wall 2 is reinforced and sealed to restore the overall support performance and water-stopping properties of the diaphragm wall 2. Then, the conditions for deep foundation pit excavation are met.

[0039] 7) When selecting the dimensions and wall thickness parameters of the culvert, choose those that meet the stiffness requirements of the internal support. Remove the culverts outside the diaphragm wall 2, and reinforce the steel rings within the thickness range of the diaphragm wall 2 with poured concrete. The culvert portion inside the foundation pit of the diaphragm wall 2 is retained as a steel support component within the second-phase foundation pit area 6, thereby achieving material reuse and saving project costs. In some cases, the culvert 8 can also be grouted to become a reinforced concrete support component; or the culvert 8 can be directly used as a mold for pouring the concrete support components inside the diaphragm wall.

[0040] This embodiment achieves the coordinated advancement of ultra-deep foundation pit construction and uninterrupted river flow, while simultaneously addressing the operability and safety issues of culvert penetration through the ground wall. Compared to existing open river relocation and river flow interruption technologies, this method does not require altering the original river course or blocking water flow, and balances construction needs and river function through in-situ / ex-situ diversion.

[0041] Although the above embodiments have described the concept and embodiments of the present invention in detail with reference to the accompanying drawings, those skilled in the art will recognize that various improvements and modifications can still be made to the present invention without departing from the scope of the claims, and therefore will not be elaborated here.

Claims

1. A construction method for an ultra-deep foundation pit crossing a river, comprising a diaphragm wall serving as the support structure for the ultra-deep foundation pit, wherein the flow path of the ultra-deep foundation pit interferes with the flow path of the river, i.e., the flow path of the river passes through the construction area of ​​the ultra-deep foundation pit, characterized in that: The construction method includes: Within the area of ​​the underground continuous wall, a sealing wall is constructed, which divides the ultra-deep foundation pit into a first-phase foundation pit and a second-phase foundation pit, wherein the first-phase foundation pit completely covers the flow path of the river channel; A culvert is installed on the underground continuous wall corresponding to the second-phase foundation pit. The culvert passes through the construction area of ​​the second-phase foundation pit. One end of the culvert is connected to a river channel outside one side of the first-phase foundation pit, and the other end is connected to a river channel outside the other side of the first-phase foundation pit. The culvert forms a river channel diversion channel that avoids the first-phase foundation pit. While the culvert is diverting water into the river, the construction of the first-phase foundation pit is carried out. After the first phase of foundation pit construction is completed, the culvert will be removed and the underground continuous wall corresponding to the second phase of foundation pit will be restored by grouting.

2. The construction method for an ultra-deep foundation pit across a river according to claim 1, characterized in that: During the construction of the diaphragm wall, a pre-embedded steel ring is welded into the reinforcing cage inside. This pre-embedded steel ring becomes an opening in the diaphragm wall for connection between the diaphragm wall and the culvert. The culvert is then connected and fixed to the pre-embedded steel ring.

3. The construction method for an ultra-deep foundation pit across a river according to claim 1, characterized in that: The culvert is divided into two turning pipe sections and one crossing pipe section. The two turning pipe sections are fixedly connected to the outside of the pre-embedded steel rings, and the two ends of the crossing pipe section are fixedly connected to the inside of the pre-embedded steel rings on both sides.

4. The construction method for an ultra-deep foundation pit across a river according to claim 3, characterized in that: When the culvert is removed, the crossing pipe section will also serve as the steel support for the underground continuous wall corresponding to the second-phase foundation pit.

5. The construction method for an ultra-deep foundation pit crossing a river according to claim 4, characterized in that: Grouting is performed on the crossing pipe section that also serves as a steel support to form a reinforced concrete support, or the crossing pipe section is used as a mold for the concrete support construction.

6. The construction method for an ultra-deep foundation pit crossing a river according to claim 1, characterized in that: Construction of a reinforcing sidewall on the outer side of the diaphragm wall located at the opening location.

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