Overpass existing structure pipe gallery branch warehouse construction method

Abstract

The invention relates to the technical field of urban comprehensive pipe gallery construction, in particular to an over-crossing existing structure pipe gallery bin division construction method, which is characterized in that the area of an over-crossing existing structure of a to-be-built comprehensive pipe gallery is longitudinally divided into a plurality of independent construction bin bodies for respective construction by adopting a bin division method; foundation reinforcement is carried out in advance in a skip construction mode, then foundation pit excavation and structure construction are carried out in a staging construction mode, meanwhile, construction is carried out in a symmetrical skip sequence from edge sections on the two sides to a center core section step by step, the influence of foundation pit excavation on an existing tunnel below can be accurately controlled while the construction efficiency is guaranteed, and the construction efficiency is improved. And disturbance of excavation unloading to the tunnel is reduced, upward floating and horizontal displacement of the tunnel are effectively restrained, the structure safety of the underlying tunnel and the controllability of the pipe gallery construction process are guaranteed, and therefore the purposes of safety, high efficiency and economy are achieved. The comprehensive pipe gallery construction method can be effectively suitable for overcrossing existing structures and particularly suitable for highway tunnel working conditions.

Description

Technical Field

[0001] This invention relates to the field of urban integrated utility tunnel construction technology, and in particular to a method for compartmentalized construction of a utility tunnel spanning existing structures. Background Technology

[0002] Urban underground utility tunnels are a key infrastructure project that utilizes underground space in an intensive and scientific manner. Among the various construction methods for utility tunnels, the open-cut method has become the mainstream due to its mature technology, convenient construction, and relatively low cost. Specifically, the open-cut continuous construction method has significant advantages such as high construction efficiency and short construction period under favorable geological conditions and with minimal requirements for environmental disturbance.

[0003] However, the traditional open-cut continuous excavation method has inherent limitations. This method typically involves large-scale, continuous excavation of foundation pits, leading to the rapid and extensive removal of soil within the construction area. This causes drastic changes in the foundation stress field, resulting in a significant unloading effect. If the traditional open-cut continuous excavation method is used for integrated utility tunnels that span existing buildings, excessive concentrated unloading may cause the existing structures to float, leading to problems such as deformation, horizontal displacement, and cracking, affecting their structural safety. This method also presents significant construction risks, high difficulty, and uncontrollable construction schedules.

[0004] Therefore, in order to ensure faster, safer, and more efficient completion of the integrated utility tunnel construction, it is necessary to improve and adjust its construction methods. Summary of the Invention

[0005] The purpose of this invention is to overcome the shortcomings of existing technologies where the excavation and unloading of integrated utility tunnels under the working conditions of crossing existing buildings (structures) has a large upward floating impact, and to provide a compartmentalized construction method for utility tunnels crossing existing structures.

[0006] This invention provides a method for constructing a utility tunnel spanning an existing structure in sections, comprising the following steps: Foundation reinforcement: The area where the integrated utility tunnel to be built crosses the existing structure is divided longitudinally into several independent construction compartments. The number of construction compartments is odd. Mixing piles are driven in a skip-driving manner for each construction compartment, with at least one construction compartment spaced apart, to reinforce the foundation. After the reinforced soil reaches the preset strength, the adjacent sections are reinforced. After the soil strength of the construction compartment reaches the preset strength, the foundation pit is excavated and the pipe gallery structure is constructed. The foundation pit excavation and structure are carried out in stages. After the first stage is completed and backfilling is finished, the next stage of construction will be carried out. The construction of each construction compartment is carried out in a symmetrical skip-compartment sequence from the two side edge sections to the central core section.

[0007] For example, when the area of ​​the integrated utility tunnel that crosses an existing structure is divided into three construction zones (i.e., construction zones corresponding to three construction chambers), the construction is carried out in a symmetrical skip-construction sequence from the two edge sections to the central core section. That is, the foundation pit excavation and structural construction are carried out in the order of Phase I and Phase II. Among them, Phase I construction includes the construction of Zone 1 and Zone 3, and Phase II construction includes the construction of Zone 2. Phase II construction will be carried out after Phase I construction is completed and backfilled.

[0008] If the area of ​​the integrated utility tunnel spanning an existing structure is divided into five construction zones (corresponding to five construction sections), construction will proceed in a symmetrical, skip-section manner, starting from the outer edge sections and gradually moving towards the central core section. This means excavation and structural construction will proceed sequentially in the order of Phase I, Phase II, and Phase III. Phase I includes construction of Zones 1 and 5; Phase II includes construction of Zones 2 and 4; and Phase III includes construction of Zone 3. Phase II will commence after Phase I is completed and backfilled, and Phase III will commence after Phase II is completed and backfilled. This process will continue in this manner.

[0009] In each phase of construction, at least two construction zones within it are constructed in parallel or sequentially.

[0010] This plan employs a compartmentalized approach, dividing the area of ​​the planned integrated utility tunnel spanning existing structures longitudinally into several independent construction compartments for separate construction. During construction, a skip-compartment construction method is used to reinforce the foundation beforehand, restraining soil movement at the bottom and sides of the pit and improving its stability. After the reinforced soil has solidified and reached its strength, adjacent sections are reinforced to reduce the disturbance of the already stabilized soil above the existing tunnel caused by liquefaction during reinforcement work. After the foundation reinforcement work of the construction compartments to be built is completed, the pit excavation and structural construction are carried out in stages. The next stage of construction begins after the first stage is completed and backfilled. This approach reduces the length of the pit construction in sections, minimizes the unloading and disturbance of the strata during excavation and structural construction, and reduces the impact on the uplift of the lower tunnel. Furthermore, each section is independent of the others, and backfilling can be carried out promptly after the structure is completed, allowing for the rapid formation of a stable load and achieving stress balance, resulting in high construction efficiency. This scheme, by employing a symmetrical, skip-construction sequence from the two peripheral sections towards the central core section, decomposes the overall unloading risk into multiple reliable local processes, minimizing the continuous unloading benefits of the excavation on the underlying tunnel. Using this construction method significantly reduces the disturbance to the tunnel caused by excavation and unloading, effectively suppressing tunnel uplift and horizontal displacement.

[0011] Preferably, the length of a single construction compartment is 15-25 meters to control the amount of unloading per operation.

[0012] Preferably, the number of construction compartments is 7.

[0013] Preferably, the construction interval between two adjacent construction sections is not less than 7 days to reduce the disturbance of the already stabilized soil above the existing buildings (structures) caused by liquefaction during reinforcement.

[0014] Preferably, within each construction compartment, the mixing piles are constructed using a staggered pile driving method.

[0015] Preferably, in the phased construction steps of foundation pit excavation and structure, in the same phase, the earthwork excavation of the next construction section is carried out only after the pipe gallery structure of the previous construction section is completed and backfilled. This helps to reduce the unloading effect on the soil above the existing buildings (structures). Timely backfilling after the structure is completed can quickly stabilize the load and achieve stress balance.

[0016] Preferably, the excavation of the foundation pit adopts a vertical layered excavation method, including the following steps: the first layer is excavated to the bottom of the cap beam, the second layer is excavated to 50cm below the second support or half the depth of the foundation pit, and the third layer is excavated to the base.

[0017] Preferably, the excavation depth of each layer of earthwork does not exceed 4m.

[0018] Preferably, when excavating the first layer of soil, excavation equipment is used to excavate to 0.3m-0.6m below the first support; when excavating the second layer of soil, the middle part is first excavated by trenching, and then the remaining soil on both sides is excavated, with a working platform of a specified width reserved on both sides.

[0019] Preferably, the structural construction includes the following steps: after excavation to the foundation, a concrete cushion layer, a waterproof layer, a fine stone concrete protective layer, and a base slab are constructed sequentially from bottom to top; after the base slab reaches the design strength, the side walls and central partition walls are reinforced and installed; after the side walls and central partition walls are reinforced and installed, the top slab formwork and reinforcement are installed, and the side wall concrete and top slab concrete are poured together.

[0020] Compared with the prior art, the beneficial effects of the present invention are as follows: This invention provides a compartmentalized construction method for utility tunnels spanning existing structures. By employing a compartmentalized method, the area of ​​the utility tunnel spanning the existing structure is longitudinally divided into several independent construction compartments for separate construction. During construction, a skip-compartment construction method is used for foundation reinforcement beforehand, followed by phased construction of the foundation pit and structural construction. Simultaneously, by adopting a symmetrical skip-compartment construction sequence from the peripheral sections to the central core section, construction efficiency can be ensured while precisely controlling the impact of foundation pit excavation on the existing tunnel below. This reduces disturbance to the tunnel during excavation and unloading, effectively suppressing tunnel uplift and horizontal displacement, ensuring the structural safety of the underlying tunnel and the controllability of the utility tunnel construction process, thereby achieving the goals of safety, efficiency, and economy. This invention is effectively applicable to the construction of utility tunnels spanning existing structures, especially highway tunnels. Attached Figure Description

[0021] Figure 1 A schematic diagram of the construction of the planned integrated utility tunnel in different zones; Figure 2 This is a schematic diagram of the planned integrated utility tunnel and tunnel. Figure 3 This is a cross-sectional view of the foundation pit. Detailed Implementation

[0022] The present invention will now be described in further detail with reference to specific embodiments. However, this should not be construed as limiting the scope of the present invention to the following embodiments; all technologies implemented based on the content of the present invention fall within the scope of the present invention.

[0023] Unless otherwise specified, the use of terms such as "upper," "lower," "left," "right," "center," "inner," and "outer" to indicate orientation or positional relationships in the description of specific embodiments of the present invention is based on the orientation or positional relationships shown in the accompanying drawings, or the orientation or positional relationship in which the product / equipment / device is typically placed during use. These terms are merely for the purpose of facilitating the description of the present invention or simplifying the description in specific embodiments, enabling those skilled in the art to quickly understand the solution, and do not indicate or imply that a particular device / component / element must have a specific orientation, or be constructed and operated in a specific positional relationship. Therefore, they should not be construed as limitations on the present invention.

[0024] Furthermore, the use of terms such as "horizontal," "vertical," "suspended," and "parallel" does not imply that the corresponding device / component / element must be absolutely horizontal, vertical, suspended, or parallel, but rather that it can be slightly tilted or have a deviation. For example, "horizontal" merely means that its direction is more horizontal relative to "vertical," not that the structure must be completely horizontal, but that it can be slightly tilted. Alternatively, it can be simplified to mean that the corresponding device / component / element, when set in a "horizontal," "vertical," "suspended," or "parallel" direction, can have an error / deviation of ±10% relative to the corresponding direction, more preferably within ±8%, more preferably within ±6%, more preferably within ±5%, and more preferably within ±4%. As long as the corresponding device / component / element is within the error / deviation range, it can still achieve its function in the present invention.

[0025] Furthermore, the use of terms such as "first," "second," and "third" in terminology is merely for distinguishing descriptions of identical or similar components and should not be interpreted as emphasizing or implying the relative importance of a particular component.

[0026] Furthermore, in the description of the embodiments of the present invention, "several", "more than", and "a number of" represent at least two. The number can be any number, such as 2, 3, 4, 5, 6, 7, 8, or 9, and can even exceed nine.

[0027] Furthermore, in the description of the technical solution of this invention, unless otherwise explicitly specified / limited / restricted, the terms "set up," "install," "connect," "link," "provided with," "laid out," and "arranged" should be interpreted broadly. For example, they can refer to fixed connections, detachable connections, or integral connections; they can refer to common connection methods in the art, such as welding, riveting, bolting, and threaded connections. Such connections can be mechanical, electrical, or communication connections; they can be direct connections or indirect connections through an intermediate medium; and they can refer to the internal communication between two components.

[0028] Example A method for constructing a utility tunnel spanning an existing structure in sections includes the following steps: Foundation reinforcement: Based on the burial depth, structural sensitivity and geological conditions of the tunnel below, the area of ​​the integrated utility tunnel to be built that crosses the existing structure is divided longitudinally into several independent construction chambers. The number of construction chambers is set to an odd number. Mixing piles are driven into each construction area in a skip-driving manner with at least one construction chamber between them to reinforce the foundation. After the reinforced soil reaches the preset strength, the adjacent sections are reinforced. After the soil strength of the construction compartment reaches the preset strength, the foundation pit is excavated and the pipe gallery structure is constructed. The foundation pit excavation and structure are carried out in stages. After the first stage is completed and backfilled, the next stage of construction will be carried out. The construction of each construction compartment is carried out in a symmetrical skip-compartment sequence from the two side edge sections to the central core section.

[0029] By employing a compartmentalized approach, the area of ​​the planned integrated utility tunnel spanning the existing structure is longitudinally divided into several independent construction compartments for separate construction. During construction, a skip-compartment construction method is used to reinforce the foundation in advance, restraining the movement of soil at the bottom and sides of the pit and improving the stability of the pit. After the reinforced soil has solidified and reached its strength, the adjacent sections are reinforced, reducing the disturbance of the already stable soil above the existing tunnel to liquefy during the reinforcement work. After the foundation reinforcement work of the construction compartment is completed, the pit excavation and structural construction are carried out in stages. The next stage of construction begins after the first stage is completed and backfilled. This approach has two advantages: first, it reduces the length of the pit construction in sections, reduces the unloading and disturbance of the strata caused by excavation and structural construction, and reduces the impact on the uplift of the lower tunnel; second, each section is independent of each other, and backfilling can be carried out in a timely manner after the structure is completed, so as to quickly form a stable load and achieve stress balance, resulting in high construction efficiency. This scheme, by employing a symmetrical, skip-construction sequence from the two peripheral sections towards the central core section, decomposes the overall unloading risk into multiple reliable local processes, minimizing the continuous unloading benefits of the excavation on the underlying tunnel. Using this construction method significantly reduces the disturbance to the tunnel caused by excavation and unloading, effectively suppressing tunnel uplift and horizontal displacement.

[0030] Taking a utility tunnel crossing an existing major highway tunnel as an example, the specific construction steps are explained. Based on the geological conditions and the relationship with the existing roadway, the affected area of ​​the utility tunnel crossing the existing structure was divided into seven construction zones of equal length (corresponding to seven construction compartments). The length of a single construction compartment is preferably set at 15-25 meters to control the unloading volume at one time. Figure 1 , Figure 2 As shown, the overall construction process is as follows: foundation reinforcement (zoning and skipping between zones 1→3→5→7→2→4→6) → construction of construction method piles → construction of capping beam and first support → excavation and structural construction of phase one (zones 1 and 7) → excavation and structural construction of phase two (zones 2 and 6) → excavation and structural construction of phase three (zones 3 and 5) → excavation and structural construction of phase four (zone 4).

[0031] 1. Foundation reinforcement construction Following the construction process: Zone 1 → Zone 3 → Zone 5 → Zone 7 → Zone 2 → Zone 4 → Zone 6.

[0032] The soil mixing pile foundation reinforcement adopts a "zonal skip-driving" method, with an interval of no less than 7 days between adjacent zones to reduce the disturbance of the already stable soil above existing buildings and structures caused by liquefaction during reinforcement operations. Within each construction zone, soil mixing piles are constructed using a skip-driving method with alternating piles.

[0033] The construction steps include: (1) Surveying and site clearing: According to the design drawings, the pile positions are laid out. First, the coordinates of the corner points (or turning points) of the center line of the three-axis mixing pile are calculated based on the design drawings and the coordinate reference points provided by the owner. The center line of the three-axis mixing pile is laid out using surveying instruments. Second, a pile layout plan is drawn according to the design, the arrangement number is marked, and the specific pile positions are laid out.

[0034] (2) Trenching: The trench is excavated using a backhoe excavator. The specific width is determined according to the design diameter of the pile.

[0035] (3) Piling machine positioning and verticality correction: Direct the piling machine to be positioned, and the deviation shall not exceed 50mm. Use measuring instruments to observe and ensure that the verticality of the drilling machine is not less than 1 / 100. Before construction, mark the drill rod and control the length of the mixing pile to be not less than the designed pile length.

[0036] (4) Mix and transport cement slurry to ensure the stability of slurry quality.

[0037] (5) Drilling, mixing and lifting: When reinforcing the three-axis mixing pile, the cement and the original soil must be mixed evenly. Grouting is required during the lifting process, and the sinking and lifting speed must be strictly controlled. Grouting and mixing are carried out at the same time during lifting to ensure that the cement slurry and the original foundation soil are fully mixed. The grout pump is turned off after the pile is lifted to the design elevation.

[0038] 2. Excavation of foundation pit and structural construction To minimize the continuous unloading effect of the foundation pit excavation on the underlying tunnel, this project adopts the principle of "symmetrical unloading and stress buffering" in a stepped-down manner. First, the soil pressure at the far end (zones 1 and 7) is released; then, the process gradually transitions inward, releasing the soil pressure in the intermediate transition area (zones 2 and 6); finally, after the surrounding structures provide support, the soil pressure in the core area (zones 3, 5, and 4) is released, thus decomposing the overall unloading risk into multiple controllable local processes. The construction sequence follows this pattern: Phase I (zones 1 and 7) excavation and structural construction → Phase II (zones 2 and 6) excavation and structural construction → Phase III (zones 3 and 5) excavation and structural construction → Phase IV (zone 4) excavation and structural construction.

[0039] The excavation and structure of the foundation pit are carried out in phases. The next phase of construction begins after the first phase is completed and backfilling is finished. This approach aims to reduce the length of the foundation pit in each section, minimize the unloading and disturbance of the strata caused by the excavation and structural construction processes, and reduce the impact on the uplift of the lower tunnel. Furthermore, each section is independent of the others, and backfilling can be carried out in a timely manner after the structure is completed, so as to form a stable load as soon as possible and achieve stress balance.

[0040] In the same phase, this embodiment preferably proceeds with the excavation of the next construction section only after the pipe gallery structure of the previous construction section has been completed and backfilled. Excavation and unloading are carried out only within a small construction section at a time, ensuring that the stress release and backfilling scale are small each time, the rebound force is controllable, and the initial impact on adjacent structures is greatly reduced. After the excavation of a construction section, a heavy reinforced concrete pipe gallery structure is immediately poured, followed by backfilling, tightly integrating with the surrounding soil. The weight of this newly poured pipe gallery structure and the backfill soil is equivalent to reapplying a permanent, similar-weight ballast to the original soil in the "unloading pit" created by the excavation. This new ballast will again press down on the underlying soil, inhibiting its continued rebound and stabilizing the stress state at a new equilibrium point. When the next adjacent construction section is excavated, the resulting soil stress release and rebound trend will be constrained by the completed and stable construction section structure, thus limiting the transmission of deformation to distant locations (especially towards buildings). As another possible implementation method, the two symmetrical construction areas in the same phase can be constructed simultaneously, depending on the actual working conditions.

[0041] (1) Excavation method of foundation pit The foundation pit excavation was carried out in layers and sections, with longitudinal compartmentalization and vertical layering, such as... Figure 3 As shown, the first layer of excavation extends to the bottom of the capping beam (approximately 1.5m), the second layer extends to 50cm below the second support or half the depth of the pit (approximately 3m if only one support is installed), and the third layer extends to the foundation. Each layer of earthwork is excavated to a depth not exceeding 4m, divided into several smaller excavation layers. A platform at least 3m wide is left between the slopes of each earthwork layer. Steel supports are erected simultaneously with excavation; once a support location is found, the steel support must be erected within 8 hours.

[0042] ① First layer of earthwork excavation Excavation equipment was used to excavate to a depth of 0.5 meters below the first support, and the excavated material was transported away by dump trucks.

[0043] ② Second layer of earthwork excavation Two excavators were used for the second layer of earthwork excavation, employing a relay excavation method. First, the central section was excavated, with a width of 4m and a depth not exceeding 4m. Then, the remaining earthwork on both sides was excavated, leaving a 1m working platform on each side for the installation of steel support brackets, while also preventing damage to the retaining structure from the machinery. The excavated earthwork was relayed to the first major layer, where it was transported to the ground by the excavators on the previous layer, and then loaded into dump trucks for transport to the spoil disposal site.

[0044] ③ Third layer of earthwork excavation The excavation method is the same as that for the second layer of earthwork.

[0045] ④ Excavation of remaining foundation pit soil A small excavator and a long-arm excavator work together to excavate the soil from the foundation pit to the surface for loading and transportation. A safety officer must be present during long-arm excavator operation, and personnel are strictly prohibited from entering the operating radius.

[0046] (2) Structural construction ① Layout of construction zones and construction sequence The construction of the main structure followed the excavation, and the construction sequence was the same as the excavation sequence.

[0047] ② Vertical construction process Excavate to the foundation and promptly pour a concrete cushion layer. After the cushion layer reaches its strength, lay a waterproof layer. After the waterproof layer is laid, pour a fine aggregate concrete protective layer. After the protective layer reaches its strength, construct the bottom slab reinforcement and pour the bottom slab concrete. After the bottom slab concrete reaches its design strength, install the reinforcement for the side walls and central partition walls. After the side walls and central partition walls are installed, install the top slab formwork and reinforcement. Pour the side wall concrete together with the top slab concrete. After the structural construction of each section is completed and the strength meets the design requirements, backfill the earthwork. Backfilling should be carried out in layers with compaction, and the compaction degree should meet the design requirements.

[0048] Using the above construction method, all monitoring data during construction were within normal ranges, ensuring the safety and stability of the tunnel structure, ground surface, and surrounding buildings and structures, and maintaining a controllable construction period. This method minimizes ground disturbance and concentrated unloading, effectively reducing settlement and displacement of existing tunnels and minimizing construction risks. It boasts advantages such as high safety, good construction quality, minimal environmental impact, and high social benefits, and can be widely applied in the construction of underground integrated utility tunnels spanning important structures such as existing railway, highway, and subway tunnels.

[0049] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for constructing a pipe gallery warehouse across an existing structure, characterized in that, The method comprises the following steps: Foundation reinforcement: the area of the comprehensive pipe gallery to be built overpassing the existing structures is divided into several independent construction bays in the longitudinal direction, the number of the construction bays is odd, and the foundation reinforcement is performed on each construction bay by using the method of interval at least one construction bay to jump and mix piles, and the foundation reinforcement of the construction bays of adjacent sections is performed after the reinforced soil reaches the preset strength; After the soil strength of the construction bay reaches the preset strength, the foundation pit is excavated and the pipe gallery structure is constructed: the foundation pit excavation and the structure are constructed by stages, the next stage construction is performed after the first stage construction is completed and backfilled, and the construction bays are symmetrically constructed in the order of jumping the bays from the two side edge sections to the central core section.

2. The pipe gallery construction method across an existing structure according to claim 1, wherein The length of a single construction bay is 15-25 meters.

3. The method according to claim 1, wherein The number of the divided construction bays is 7.

4. The method according to claim 1, wherein The construction interval of the adjacent two construction bays is not less than 7 days.

5. The method according to claim 1, wherein, In each construction bay, the mixing piles are constructed by using the method of interval piles.

6. The method according to claim 1, wherein, In the step of the foundation pit excavation and the structure constructed by stages, in the same stage, the soil excavation of the next zone construction bay is performed after the pipe gallery structure construction of the previous zone construction bay is completed and backfilled.

7. The method according to claim 1, wherein, The vertical layer excavation method is adopted for the foundation pit excavation, which comprises the following steps: the first layer is excavated to the bottom of the corbel, the second layer is excavated to 50cm below the second support or half of the foundation pit depth, and the third layer is excavated to the base.

8. The method according to claim 7, wherein, The soil excavation depth of each layer is not more than 4m.

9. The method according to claim 7, wherein the method is characterized by, In the case of excavating the first layer of soil, the excavation equipment is used to excavate to 0.3-0.6m below the first support; In the case of excavating the second layer of soil, the middle part is first excavated by trenching, then the remaining soil on both sides is excavated, and a designated width of working platform is reserved on both sides.

10. The method according to any one of claims 1-9, wherein, The structure construction comprises the following steps: after excavating to the base, the concrete cushion, the waterproof layer, the fine stone concrete protection layer and the bottom plate are constructed in turn from bottom to top; after the bottom plate reaches the design strength, the reinforcement of the side wall and the partition wall is installed, the top plate formwork and reinforcement are installed after the reinforcement of the side wall and the partition wall is installed, and the side wall concrete and the top plate concrete are poured together.

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