Construction method of mechanical pipe jacking line conflicting with existing structure

Abstract

The application discloses a kind of mechanical pipe jacking jacking line and existing structure conflict construction method, and existing structure includes existing well room, existing well room is sequentially provided with existing shaft, pipeline inspection well, existing pipeline from ground elevation below, new pipeline on mechanical pipe jacking jacking line is located above pipeline inspection well, and part of pipe position of new pipeline conflicts with existing well room, construction method includes the following steps: excavation of foundation pit in existing well room and removal of corresponding section of existing shaft;According to the wall of existing well room is broken at the position of conflict, the wall of existing well room is broken;Bottom support beam assembly is constructed at the excavation base of foundation pit;Support beam plate, support bottom plate and support wall are constructed at the broken hole opening;Backfilling is carried out in the range of foundation pit, new shaft is installed and top support beam assembly is constructed, the application breaks local structural obstacles after open excavation of foundation pit, and the risk of collapse of foundation pit is avoided by soil excavation in existing stable structure, the overall operation is safe and controllable, and has high popularization value.

Description

Technical Field

[0001] This invention relates to the field of building construction technology, and in particular to a construction method for mechanical pipe jacking routes that conflict with existing structures. Background Technology

[0002] Currently, mechanical pipe jacking is often used for urban water supply networks. However, due to the complexity of the existing pipeline network, unclear pipe locations, and the fact that most preliminary investigations are only at the stage of surveying surface lines and manhole covers, as well as incomplete information on underground engineering, conflicts with underground obstacles are inevitable during pipe jacking construction.

[0003] Regarding the aforementioned mechanical pipe jacking construction route, where half of the pipe location conflicts with the existing manhole structure, the conventional handling methods and their drawbacks are as follows:

[0004] 1) Removing the already jacked-in pipeline and adjusting the route. This method is costly and carries significant risks, with uncontrollable safety risks.

[0005] 2) After the pipe has been jacked in, the machine head is partially removed inside the pipe to break up local structural obstacles. This method of working inside the tunnel without support poses safety risks of tunnel collapse and confined space operations. Summary of the Invention

[0006] To overcome the shortcomings of existing technologies, this invention provides a construction method for mechanical pipe jacking that conflicts with existing structures. This method involves excavating from the ground to remove local structural obstacles, ensuring the smooth progress of pipe jacking construction for new pipelines.

[0007] To achieve the above objectives, this invention provides a construction method for addressing conflicts between a mechanical pipe jacking route and an existing structure. The existing manhole contains, from ground level downwards, an existing shaft, a pipeline inspection manhole, and an existing pipeline. A newly constructed pipeline on the mechanical pipe jacking route is located above the pipeline inspection manhole, and a portion of the new pipeline conflicts with the existing manhole. The construction method includes the following steps:

[0008] Excavation of the foundation pit is carried out on the ground to the existing manhole, and the corresponding section of the existing manhole is demolished at the same time, so that the foundation pit excavation base is located below the new pipeline.

[0009] The demolition area is defined at the conflict location, making the area of ​​the demolition area larger than the cross-sectional area of ​​the new pipeline. The existing manhole wall is then demolished at the conflict location according to the demolition area to form a demolition opening.

[0010] At the excavation base of the foundation pit, construct the bottom support beam assembly so that the bottom support beam assembly forms the first channel corresponding to the existing shaft;

[0011] Construct support beams and support base plates at the locations corresponding to the breach openings within the existing manhole, so that the first end of the support beams is fixedly connected to the top wall of the breach opening, the first end of the support base plates is fixedly connected to the bottom wall of the breach opening, and a support wall is fixedly installed between the second end of the support beams and the second end of the support base plates.

[0012] Backfilling is carried out within the foundation pit area. During backfilling, a new well cylinder is installed simultaneously above the existing well cylinder, so that the new well cylinder and the existing well cylinder are connected through the first channel. When backfilling reaches the bottom elevation of the ground road base, a top support beam assembly is constructed on the outside of the new well cylinder, so that the top support beam assembly forms a second channel corresponding to the new well cylinder.

[0013] Preferably, when excavating the foundation pit in the existing manhole, the excavation should be carried out in layers to a position at least 1m below the new pipeline, and the thickness of each layer should not exceed 2m.

[0014] Preferably, when defining the demolition area at the conflict location, the demolition area is the area from no less than 20cm above the top of the new pipe to no less than 20cm below the bottom of the pipe.

[0015] Preferably, when demolishing the existing well wall at the conflict location according to the demolition range, the demolition method should be selected based on the engineering geology and the soil stability verification after the pipe jacking construction, specifically including:

[0016] For soils with high stability, direct demolition is adopted;

[0017] For soil with poor stability, grout is injected into the existing well wall to reinforce the soil before it is broken up.

[0018] Preferably, when constructing the bottom support beam assembly at the foundation pit excavation base, the bottom support beam assembly includes two parallel bottom support longitudinal beams and two bottom support transverse beams vertically fixedly connected between the two bottom support longitudinal beams. The two ends of the bottom support longitudinal beams along the length direction are respectively fixedly connected to a pair of well walls of the existing well chamber, and the two bottom support transverse beams and the two bottom support longitudinal beams enclose and form the first channel.

[0019] Preferably, after the construction of the supporting beams, supporting base plates, and supporting walls is completed, mechanical pipe jacking is used to form the new pipeline, and after the construction of the new pipeline is completed, grouting is performed within the area enclosed by the supporting beams, supporting base plates, supporting walls, and the new pipeline.

[0020] Preferably, when backfilling within the foundation pit area, a 3:7 lime-soil mixture should be used for backfilling and manual compaction in layers, and the thickness of each layer should not exceed 30cm.

[0021] Preferably, when constructing the top support beam assembly on the outside of the newly built well shaft, the top support beam assembly includes two parallel top support longitudinal beams and two top support transverse beams vertically fixed between the two top support longitudinal beams. The two ends of the top support longitudinal beams along the length direction are respectively fixedly connected to a pair of well walls of the existing well chamber, and the two top support transverse beams and the two top support longitudinal beams enclose and form the second channel.

[0022] Preferably, when constructing the top support beam assembly on the outside of the newly built well shaft, the construction of two top sealing plates is carried out simultaneously above the backfill soil, and the two top sealing plates are sealed and connected one-to-one between the two top support longitudinal beams and the well wall on the corresponding side.

[0023] By adopting the above technical solution, the present invention has the following beneficial effects:

[0024] 1) By using open excavation to remove local structural obstacles and excavating within the existing stable structure, there is no risk of the pit collapsing, and the overall operation is safe and controllable.

[0025] 2) By using a 3:7 lime-soil mixture to backfill and compact the soil layer by layer, and by using top and bottom support beams to reinforce the newly built well shaft, the adverse effects of soaking the soil at the bottom of the foundation pit on the existing well shaft and ground settlement were avoided.

[0026] 3) Within the area of ​​the breach, new support beams and base plates are constructed by installing rebar, and a support wall is built between the support beams and base plates to ensure that the new pipeline is isolated from the backfill soil. This eliminates the impact of the partial demolition of the existing structure on the overall structure of the well wall, as well as the adverse factors such as the jacking force increasing dramatically and the pipeline being subjected to stress concentration caused by the close contact or bonding between the jacking steel pipe and the soil. Attached Figure Description

[0027] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0028] Figure 1 This is a cross-sectional view of the conflict location between the newly built pipeline and the existing structure in the pipe jacking construction route of this invention embodiment.

[0029] Figure 2 This is a cross-sectional view of the excavation of the existing well chamber foundation pit and the removal of the conflict location in an embodiment of the present invention.

[0030] Figure 3This is a cross-sectional view of the newly built well shaft, top support beam assembly, bottom support beam assembly, support beam plate, support base plate, support wall, foundation pit backfill, and top sealing plate in an embodiment of the present invention.

[0031] Figure 4 This is a structural schematic diagram of the bottom support beam assembly in an embodiment of the present invention.

[0032] The correspondence between the numbers in the attached diagram is as follows:

[0033] 1- Existing manhole; 101- Existing pipeline; 102a- Existing shaft; 102b- New shaft; 103- Pipeline inspection manhole; 2- Excavation base of foundation pit; 3- New pipeline; 4- Ground elevation; 5- Demolition area; 6- Top sealing plate; 7- Bottom support beam assembly; 71- Bottom support longitudinal beam; 72- Bottom support transverse beam; 8- Backfill soil; 91- Support beam slab; 92- Support wall; 93- Support base plate; 10- Grouting filling area; 11- Top support beam assembly. Detailed Implementation

[0034] The specific embodiments of the present invention will be further described below with reference to the accompanying drawings. It should be noted that these descriptions are for the purpose of aiding understanding the present invention, but do not constitute a limitation thereof. Furthermore, the technical features involved in the various embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0035] Please see Figures 1 to 4 As shown, this invention provides a construction method for a mechanical pipe jacking route that conflicts with an existing structure. The existing structure includes an existing manhole 1, and within the existing manhole 1, from ground elevation 4 downwards, there are an existing shaft 102a, a pipeline inspection manhole 103, and an existing pipeline 101. Half of the newly constructed pipeline 3 on the mechanical pipe jacking route conflicts with the existing manhole 1. The construction method includes the following steps:

[0036] Excavation of the foundation pit is carried out on the ground into the existing well chamber 1, and the corresponding section of the existing well cylinder 102a is demolished simultaneously, so that the foundation pit excavation base 2 is located below the newly built pipeline 3.

[0037] At the conflict location, a breach range 5 is defined, such that the area of ​​the breach range 5 is larger than the cross-sectional area of ​​the newly built pipeline 3. The existing manhole wall of the existing manhole 1 is breached at the conflict location according to the breach range 5, thereby forming a breach opening.

[0038] At the foundation excavation site 2, the bottom support beam assembly 7 was constructed so that the bottom support beam assembly 7 formed the first channel corresponding to the existing well shaft 102a;

[0039] Construct a support beam plate 91 and a support base plate 93 at the location corresponding to the breach opening in the existing well chamber 1, so that the first end of the support beam plate 91 is fixedly connected to the top wall of the breach opening, the first end of the support base plate 93 is fixedly connected to the bottom wall of the breach opening, and a support wall 92 is fixedly installed between the second end of the support beam plate 91 and the second end of the support base plate 93.

[0040] Backfill soil 8 is carried out within the foundation pit area. During backfilling, a new well 102b is installed simultaneously above the existing well 102a, so that the new well 102b and the existing well 102a are connected through the first channel. When backfilling reaches the bottom elevation of the ground roadbed, a top support beam assembly 11 is constructed on the outside of the new well 102b, so that the top support beam assembly 11 forms a second channel corresponding to the new well 102b.

[0041] Furthermore, when excavating the foundation pit within the existing manhole 1, a layered excavation method is adopted to excavate to a position at least 1m below the newly constructed pipeline 3, and the thickness of each layer does not exceed 2m. It should be noted that during excavation, the road base structure is cut to break it up.

[0042] Furthermore, when defining the demolition area 5 at the conflict location, demolition area 5 is the area from at least 20cm above the top of the newly constructed pipeline 3 to at least 20cm below the bottom of the pipeline. It should be noted that when demolishing the existing manhole wall 1 at the conflict location according to demolition area 5, the demolition method is selected based on the engineering geology and the soil stability verification after the pipe jacking construction. Specifically, for soil with high stability, direct demolition is adopted; for soil with poor stability, grouting is injected into the existing manhole wall 1 to reinforce the soil before demolition. During the demolition process, the manhole wall of demolition area 5 is divided into sections, with a section height not exceeding 1.5m and a section width of approximately 1.5m. The size of the sections is considered in conjunction with the manhole wall thickness and lifting capacity. Depending on the space available, water drilling or wire sawing can be used to demolish the conflict structure. When excavating to the section line, the sections are cut. After cutting, anchor rings are installed on the opposite manhole wall, and the sections are pulled out one by one using a hand-operated hoist and then lifted away. After breaking down the well wall structure within the opening area, clear away obstacles and debris within the pipe jacking route area, pump out accumulated water within the foundation pit area, and clean and remove the soil.

[0043] Please see Figure 3 and Figure 4As shown, when constructing the bottom support beam assembly 7 at the foundation 2 of the excavation pit, the bottom support beam assembly 7 includes two parallel bottom support longitudinal beams 71 and two bottom support transverse beams 72 vertically fixed between the two bottom support longitudinal beams 71. The two ends of the bottom support longitudinal beams 71 along the length direction are respectively fixedly connected to a pair of well walls of the existing well chamber 1, and the two bottom support transverse beams 72 and the two bottom support longitudinal beams 71 enclose a first channel. It should be noted that the ends of the bottom support longitudinal beams 71 are installed by planting rebar on the corresponding well wall structure.

[0044] Furthermore, after the construction of the supporting beam 91, supporting base 93, and supporting wall 92 is completed, mechanical pipe jacking is used to form a new pipeline 3. After the new pipeline 3 is jacked up, grouting is performed within the area enclosed by the supporting beam 91, supporting base 93, supporting wall 92, and the new pipeline 3. Figure 3 As shown in the figure, the area marked 10 is the grouting filling range. By setting up supporting beams 91, supporting base plates 93, and supporting walls 92, and coordinating grouting to fill the enclosed area, it is possible to ensure the reinforcement of the breach opening while isolating the pipe jacking construction from the backfill area of ​​the foundation pit. Preferably, when backfilling soil 8 within the foundation pit area, a 3:7 lime-soil mixture is used for backfilling in layers and manually compacted, and the thickness of each backfill layer does not exceed 30cm.

[0045] Furthermore, when constructing the top support beam assembly 11 on the outside of the newly built well shaft 102b, the newly built well shaft 102b adopts a precast well shaft. The top support beam assembly 11 includes two parallel top support longitudinal beams and two top support transverse beams vertically fixedly connected between the two top support longitudinal beams. The two ends of the top support longitudinal beams along the length direction are respectively fixedly connected to a pair of well walls of the existing well chamber 1, and the two top support transverse beams and the two top support longitudinal beams enclose and form a second channel. It should be noted that the composition structure and connection method of the top support beam assembly 11 are the same as those of the bottom support beam assembly 7, so they will not be marked again in the figure. By setting the bottom support beam assembly 7 at the bottom of the newly built well shaft 102b and setting the top support beam assembly 11 at the top, the bottom support beam assembly 7 and the top support beam assembly 11 form a reinforced support for the newly built well shaft 102b, which can ensure the structural safety of the newly built well shaft 102b. Preferably, during the construction of the top support beam assembly 11, the construction of two top sealing plates 6 is carried out simultaneously above the backfill soil, and the two top sealing plates 6 are sealed and connected one-to-one between the two top support longitudinal beams and the corresponding well walls. The ends of the top support longitudinal beams and the top sealing plates 6 are installed by anchoring rebars in the corresponding well wall structures. After the concrete of the top sealing plates 6 reaches the design strength, the road surface is restored. By setting the top sealing plates 6, the amount of backfill settlement of the foundation pit can be reduced.

[0046] The embodiments of the present invention have been described in detail above with reference to the accompanying drawings, but the present invention is not limited to the described embodiments. For those skilled in the art, various changes, modifications, substitutions, and variations can be made to these embodiments without departing from the principles and spirit of the present invention, and these variations still fall within the protection scope of the present invention.

Claims

1. A construction method for a mechanical pipe jacking route that conflicts with an existing structure, wherein the existing structure includes an existing manhole, and the existing manhole contains, from ground level downwards, an existing shaft, a pipeline inspection manhole, and an existing pipeline, wherein a newly constructed pipeline on the mechanical pipe jacking route is located above the pipeline inspection manhole, and part of the newly constructed pipeline conflicts with the existing manhole, characterized in that, The construction method includes the following steps: Excavation of the foundation pit is carried out on the ground to the existing manhole, and the corresponding section of the existing manhole is demolished at the same time, so that the foundation pit excavation base is located below the new pipeline. The demolition area is defined at the conflict location, making the area of ​​the demolition area larger than the cross-sectional area of ​​the new pipeline. The existing manhole wall is then demolished at the conflict location according to the demolition area to form a demolition opening. At the excavation base of the foundation pit, construct the bottom support beam assembly so that the bottom support beam assembly forms the first channel corresponding to the existing shaft; Construct support beams and support base plates at the locations corresponding to the breach openings within the existing manhole, so that the first end of the support beams is fixedly connected to the top wall of the breach opening, the first end of the support base plates is fixedly connected to the bottom wall of the breach opening, and a support wall is fixedly installed between the second end of the support beams and the second end of the support base plates. Backfilling is carried out within the foundation pit area. During backfilling, a new well cylinder is installed simultaneously above the existing well cylinder, so that the new well cylinder and the existing well cylinder are connected through the first channel. When backfilling reaches the bottom elevation of the ground road base, a top support beam assembly is constructed on the outside of the new well cylinder, so that the top support beam assembly forms a second channel corresponding to the new well cylinder.

2. The construction method for mechanical pipe jacking lines that conflict with existing structures as described in claim 1, characterized in that... When excavating the foundation pit in the existing manhole, the excavation should be carried out in layers to a position at least 1m below the new pipeline, and the thickness of each layer should not exceed 2m.

3. The construction method for conflicting mechanical pipe jacking routes with existing structures as described in claim 1, characterized in that, When defining the demolition area at the conflict location, the demolition area shall be the area from no less than 20cm above the top of the newly built pipe to no less than 20cm below the bottom of the pipe.

4. The construction method for mechanical pipe jacking lines that conflict with existing structures as described in claim 1, characterized in that, When demolishing the existing well wall at the conflict location according to the demolition scope, the demolition method should be selected based on the engineering geology and the soil stability verification after the pipe jacking construction. Specifically, this includes: For soils with high stability, direct demolition is adopted; For soil with poor stability, grout is injected into the existing well wall to reinforce the soil before it is broken up.

5. The construction method for mechanical pipe jacking lines that conflict with existing structures as described in claim 1, characterized in that, When constructing the bottom support beam assembly at the foundation pit excavation base, the bottom support beam assembly includes two parallel bottom support longitudinal beams and two bottom support transverse beams vertically fixedly connected between the two bottom support longitudinal beams. The two ends of the bottom support longitudinal beams along the length direction are respectively fixedly connected to a pair of well walls of the existing well chamber, and the two bottom support transverse beams and the two bottom support longitudinal beams enclose and form the first channel.

6. The construction method for mechanical pipe jacking lines that conflict with existing structures as described in claim 1, characterized in that, After the construction of the supporting beams, supporting base plate, and supporting wall is completed, the new pipeline is formed by mechanical pipe jacking. After the new pipeline is jacked, grouting is performed within the area enclosed by the supporting beams, supporting base plate, supporting wall, and the new pipeline.

7. The construction method for mechanical pipe jacking lines that conflict with existing structures as described in claim 1, characterized in that, When backfilling within the foundation pit area, a 3:7 lime-soil mixture should be used for backfilling and manual compaction in layers, and the thickness of each layer should not exceed 30cm.

8. The construction method for mechanical pipe jacking lines that conflict with existing structures as described in claim 1, characterized in that, When constructing the top support beam assembly on the outside of the newly built well, the top support beam assembly includes two parallel top support longitudinal beams and two top support transverse beams vertically fixed between the two top support longitudinal beams. The two ends of the top support longitudinal beams along the length direction are respectively fixedly connected to a pair of well walls of the existing well chamber, and the two top support transverse beams and the two top support longitudinal beams enclose and form the second channel.

9. The construction method for mechanical pipe jacking lines that conflict with existing structures as described in claim 8, characterized in that, When constructing the top support beam assembly on the outside of the newly built well, the construction of two top sealing plates is carried out simultaneously above the backfill soil, and the two top sealing plates are sealed and connected one-to-one between the two top support longitudinal beams and the well wall on the corresponding side.

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