Existing tunnel rerouting conversion well and construction method thereof

Abstract

The invention provides an existing tunnel rerouting conversion well and a construction method thereof.The conversion well is connected with a reserved section and an abandoned section of a tunnel and performs temporary plugging, the conversion well comprises fender posts, a lining structure and a reinforcing structure, the fender posts are used for enclosing a foundation pit, an all-casing slewing drilling machine is adopted for secant pile construction, pile bodies penetrate through the reserved section of the existing tunnel and are embedded into bedrock, and the lining structure is arranged on the lining structure; the lining structure is arranged in a foundation pit and comprises a wall plate and a top plate of a reserved hole casing pipe, and the casing pipe is in lap joint with a newly-built tunnel through an annular steel plate. The reinforcing structure comprises a water stop closed loop formed by grouting reinforcement of soil outside a newly-built tunnel opening and reinforcement of soil around a tunnel through MJS construction method piles, and for a waste section, plugging operation is adopted to ensure the stability of a site; for the reserved section, the structural stability and waterproof control of the joint of the new tunnel and the old tunnel are emphatically achieved, and temporary measures in the construction period and permanent measures in the later use stage are taken into consideration.

Description

Technical Field

[0001] The invention relates to the technical field of tunnel construction, and in particular to an existing tunnel rerouting conversion shaft and a construction method thereof. Background Art

[0002] Tunnels are an important structure widely used in various municipal and water conservancy facilities, and there are currently huge stocks in my country. Existing long tunnels usually have a large longitudinal extension and depth, which makes maintenance work quite difficult and complicated. The construction of adjacent buildings (structures) and municipal road systems will have a certain impact on the structural safety and durability of tunnels, and the existence of tunnels will also bring certain safety hazards to the structural safety of newly built adjacent buildings (structures) and municipal road systems. In addition, there are many cases of plane intersections between new projects and existing tunnels. Therefore, it is necessary to carry out research on tunnel relocation plans. Tunnel rerouting projects generally include the blocking of abandoned parts of the tunnel, temporary reinforcement of the retained parts of the tunnel during the construction period and permanent reinforcement after construction, and the construction of the new parts of the tunnel, involving blocking, conversion well design, reinforcement protection and waterproofing treatment. Summary of the invention

[0003] The purpose of the present invention is to overcome the shortcomings of the prior art and provide a tunnel rerouting conversion shaft and a construction method thereof, so as to achieve the sealing of the abandoned section of the tunnel, the construction of the new section, and the reinforcement, protection and waterproofing of the retained section.

[0004] In order to achieve the above object, the present invention provides a method for constructing a conversion well for an existing tunnel, comprising the following steps:

[0005] S1: Construction preparation, review the tunnel plane positioning and elevation, and make sure they are consistent with the geophysical and geological survey data;

[0006] S2: Temporarily seal the ends of the existing tunnel’s retained and abandoned sections, and fill the tunnel with grouting;

[0007] S3: Strengthen the interface between the transfer shaft and the tunnel retention section, set up a steel arch frame inside the retention section and fill it with lightweight concrete before the construction of retaining piles;

[0008] S4: Use pile-forming equipment with obstacle-clearing and water-stopping functions to construct the transfer well retaining piles and excavate the foundation pit;

[0009] S5: construct the main structure of the conversion shaft, including the inner bottom slab and the wall slab. The inner bottom slab and the wall slab are reserved with the opening casing matching the cross-sectional size of the new tunnel;

[0010] S6: After grouting and reinforcing the soil outside the newly built tunnel entrance, the tunnel is penetrated. After the tunnel is penetrated, the surrounding soil is reinforced with horizontal MJS piles to form a water-stop closed loop, and the reserved steel casing is overlapped with the annular steel plate of the reserved section;

[0011] S7: After the new segment is fully penetrated, partition walls are built in compartments for the abandoned segment, and fillers are poured through the top shaft for plugging.

[0012] S8: Chisel off the retaining piles and lightweight concrete of the retained segment, remove the steel arch frames, weld the inner lining steel casing to the steel plate on the inner wall of the tunnel and then seal it, and backfill to the designed ground level.

[0013] Furthermore, in step S2, the grouting of the tunnel is used to offset the influence of the construction of the retaining piles on the retained segment and the abandoned segment of the tunnel, and the broken parts of the retained segment and the abandoned segment of the tunnel cannot be grouted.

[0014] Furthermore, in step S3, the horizontal spacing of the steel arch frames is 2 meters, and full penetration fillet welds are used to connect the I-beams of the steel arch frames.

[0015] Furthermore, in step S4, the retaining piles are constructed by using an all-casing rotary drilling rig for overlapping piles. Before construction, the soil within a certain range outside the tunnel entrance is grouted for reinforcement, and a water-stop curtain is arranged at the tunnel entrance. When the retaining piles, the water-stop curtain, and the soil reinforcement at the tunnel entrance meet the specified age and strength requirements, the excavation of the foundation pit begins.

[0016] Furthermore, in step S5, the steel casing reserved in the inner lining wall panel of the conversion well is overlapped with the circumferential steel plate pre-buried in the retained segment of the tunnel, and is sealed with expansive concrete.

[0017] Furthermore, in step S6, the tunnel penetration construction is carried out by using the drill-and-blast method, the pipe-jacking method or the shield method.

[0018] Furthermore, in step S7, the proposed plugging segment is compartmentalized by building partition walls, and vertical shafts are formed by drilling at the top of each compartment, and the fillers are directly poured into the tunnel through the vertical shafts.

[0019] Furthermore, in step S8, the steel casing arranged on the inner lining wall panel is welded to the steel plate on the inner wall of the existing tunnel and then sealed with expansive concrete, and water-stop measures are taken. After the construction of the new tunnel is completed, the MJS method is used to reinforce the soil around the retained segment of the tunnel to form a water-stop closed loop.

[0020] On the other hand, the present invention also provides a conversion well for the route change of an existing tunnel. The conversion well connects the retained segment and the abandoned segment of the tunnel and conducts temporary plugging, and includes retaining piles, an inner lining structure and a reinforcement structure. The retaining piles are composed of overlapping piles with casings, and the pile bodies penetrate through the retained segment of the existing tunnel and embed into the bedrock. The inner lining structure includes the wall panel and the roof plate with reserved tunnel entrance casings, and the casings are overlapped with the new tunnel through circumferential steel plates; the reinforcement structure includes the grouting reinforcement of the soil outside the new tunnel entrance and the reinforcement of the soil around the tunnel by MJS method piles to form a water-stop closed loop.

[0021] Furthermore, a steel arch frame is provided at the interface between the reserved section of the tunnel and the conversion well and filled with lightweight concrete. Masonry partition walls are provided in the abandoned plugging area for bin partitioning, and fillers are poured into the bins.

[0022] The present invention has the following beneficial effects:

[0023] (1) The construction method of the present invention provides a mature solution for the realignment of existing tunnels. For the abandoned section, plugging operations are taken to ensure the stability of the site; for the reserved section, the structural stability and waterproof control at the connection between the new and old tunnels are mainly solved, taking into account both the temporary measures during construction and the permanent measures in the later use stage.

[0024] (2) In the construction method of the present invention, the construction technology of the new tunnel can be selected from "drill and blast method", "pipe jacking method" or "shield method". Considering that the tunnels are generally buried deeply and most of the areas along the line are hard soil layers, if the open cut method is adopted, a row of piles with large stiffness + internal support scheme is required, which has a long construction period and high cost.

[0025] (3) In the construction method of the present invention, the retaining scheme of the vertical row of piles + internal support system is adopted for the foundation pit of the conversion well, which has good adaptability to the hydrogeological conditions, surrounding environment and underground obstacles of the construction site, has good water-stop effect, large overall stiffness, and has a certain ability to remove obstacles. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, the following drawings are only some embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0027] Figure 1 It is a schematic flow chart of the construction method of the conversion well of the present invention;

[0028] Figure 2 It is a general schematic diagram of the realignment of the existing tunnel of the present invention;

[0029] Figure 3 It is a plan view of the conversion well of the present invention;

[0030] Figure 4 It is a sectional view of the conversion well of the present invention;

[0031] Figure 5 It is a sectional view of the reinforcement treatment of the soil outside the tunnel at the conversion well of the present invention;

[0032] Figure 6Schematic cross-section of the internal steel arch support in the reserved section of the tunnel at the conversion well of the present invention;;

[0033] Figure 7 Schematic connection diagram of the conversion well of the present invention and the existing tunnel;

[0034] Figure 8 Schematic diagram of the grouting filling and plugging scheme for the abandoned section of the tunnel of the present invention

[0035] In the figure: 1. Conversion well, 2. Newly built tunnel, 3. Reserved section of the tunnel, 4. Abandoned section of the tunnel, 5. Retaining piles of the conversion well, 6. Lining structure of the conversion well, 7. Internal steel arch in the reserved section of the tunnel, 8. Soil reinforcement by MJS method piles, 9. Internal support in the foundation pit of the conversion well, 10. Circumferential steel plate, 11. Reserved steel casing at the hole, 12. Expansive concrete, 13. Grouting shaft, 14. Cast-in-place concrete in compartments, 15. Partition wall between compartments. Detailed implementation manners

[0036] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0037] In the following description, "some embodiments" are involved, which describe a subset of all possible embodiments. However, it can be understood that "some embodiments" can be the same subset or different subsets of all possible embodiments, and can be combined with each other without conflict.

[0038] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the technical field to which this application belongs. The terms used herein are only for the purpose of describing the embodiments of this application and are not intended to limit this application.

[0039] Figure 1 Flow chart of the construction of the conversion well for the realignment of the existing tunnel in the construction method of the present invention, as Figure 1 shown. The construction method includes:

[0040] The present invention relates to a construction method for a conversion well for the realignment of an existing tunnel, which realizes the realignment of the existing tunnel and the treatment of the abandoned section through a series of steps to ensure construction safety and structural stability. The following are the specific implementation steps of the present invention:

[0041] S1: Construction preparation

[0042] Before construction, it is necessary to review the plane positioning and elevation of the tunnel to ensure its consistency with the geophysical exploration and geological exploration data. After the review is completed, the subsequent construction stage can be entered.

[0043] S2: Temporary plugging and grouting of the tunnel.

[0044] Figure 2 This is the overall schematic diagram of the realignment of the existing tunnel of the present invention. As Figure 2 shown, in this step, the ends of the retained section 3 and the abandoned section 4 of the existing tunnel are temporarily plugged. Subsequently, the inside of the tunnel in the retained section 3 and the abandoned section 4 is filled and solidified by grouting. The grouting material is selected as lightweight concrete for easy removal in the later stage. The grouting range is the construction influence range of the conversion well retaining pile 5 on the retained section 3 and the abandoned section 4 of the existing tunnel, but the part that needs to be removed for the temporary plugging of the conversion well 1 does not need to be grouted.

[0045] S3: Reinforcement treatment of the interface.

[0046] As Figure 6 shown, the interface between the conversion well 1 and the retained section 3 of the tunnel is reinforced. Steel arch frames 7 are arranged inside the retained section 3 of the tunnel. According to the size of the tunnel section and the structural stress conditions, the horizontal spacing of the steel arch frames can be set to one every 2 meters. The steel arch frame I-beams are connected by full penetration fillet welds. At the same time, the circumferential steel plates 10 pre-buried in the retained section of the tunnel are filled and solidified with cement mortar between the inner wall of the retained section 3 of the tunnel to enhance the structural stability.

[0047] S4: Construction of the conversion well retaining pile

[0048] As Figure 3 and Figure 4 shown, the conversion well retaining pile 5 is constructed and the foundation pit is excavated. Considering that the retaining pile 5 needs to pass through the existing tunnel, its type selection needs to have a certain obstacle clearing ability and a water stop function. Generally, a full casing rotary drilling bite pile is used to meet the construction requirements.

[0049] S5: Construction of the main structure of the conversion well

[0050] When the retaining pile, the water stop curtain, the reinforcement of the hole opening soil body, etc. meet the specified age and strength requirements, the foundation pit excavation can be started. Subsequently, the lining structure 6 of the conversion well is constructed, and a hole sleeve 11 corresponding to the cross-sectional size of the newly built tunnel is reserved on the wall panel.

[0051] S6: Excavation and reinforcement of the newly built tunnel

[0052] Before the construction of the new tunnel 2, the soil within a certain range outside the tunnel entrance needs to be reinforced by grouting. The construction technology of the new tunnel can be selected from the "drilling and blasting method", "pipe jacking method" or "shield method" according to the cross-section of the new tunnel and the geological conditions along the line. The construction starts from the conversion well at one end and is completed at the conversion well at the other end. After the construction of the new tunnel 2 is completed, the accurate position of the tunnel is verified by a geological detector. Figure 5 As shown, the soil around the tunnel is reinforced with horizontal MJS piles 8 from the conversion shaft 1 to form a water-stopping closed loop. Figure 7 As shown, the steel casing 11 reserved in the lining wall of the conversion shaft is overlapped with the annular steel plate 10 pre-buried in the tunnel retention section, and is sealed with expansive concrete 12.

[0053] S7: Blocking of abandoned segments

[0054] After the new tunnel 2 is connected, both ends of the abandoned section 4 are temporarily blocked, and then the blocking operation is carried out. Figure 8 As shown, the abandoned section 4 of the tunnel is divided into compartments by building partition walls 15, and a vertical shaft 13 is formed by drilling holes at the top of each compartment. The filler 14 is directly poured into the tunnel through the vertical shaft 13 using a concrete pump truck and a hopper until the concrete is poured to 500 mm below the current ground level of the vertical shaft. Currently, the commonly used fillers are plain concrete or sand and gravel. Considering the construction convenience, filling effect and economy, the pouring C15 concrete solution is preferred.

[0055] S8: Tunnel breakthrough and backfilling

[0056] The newly built section and the reserved section tunnel are connected, and the top plate of the transfer shaft lining and the lower manhole are constructed. After reaching the designed strength, backfill to the designed ground. After the abandoned section is sealed, the retaining piles 5 and lightweight concrete within the scope of the reserved section of the tunnel are chiseled out. During the chiseling process, care must be taken not to damage the tunnel structure.

[0057] Through the above steps, the present invention realizes the safe treatment of the rerouting and abandoned sections of the existing tunnel, while ensuring the efficiency of the construction process and the stability of the structure. The above specific implementation methods are only for illustration and are not intended to limit the invention. All corresponding changes, equivalent replacements, improvements, etc. made by those skilled in the art within the technical solution and concept of the present invention without creative work should fall within the scope of protection of the claims of the present invention.

Claims

1. A method for constructing a conversion well for an existing tunnel, characterized in that: The following steps are involved: S1: Construction preparation, review the tunnel plane positioning and elevation, and make sure they are consistent with the geophysical and geological survey data; S2: Temporarily seal the ends of the existing tunnel’s retained and abandoned sections, and fill the tunnel with grouting; S3: Strengthen the interface between the transfer shaft and the tunnel retention section, set up a steel arch frame inside the retention section and fill it with lightweight concrete before the construction of retaining piles; S4: Use pile-forming equipment with obstacle-clearing and water-stopping functions to construct the transfer well retaining piles and excavate the foundation pit; S5: construct the main structure of the conversion shaft, including the inner bottom slab and the wall slab. The inner bottom slab and the wall slab are reserved with the opening casing matching the cross-sectional size of the new tunnel; S6: After grouting and reinforcing the soil outside the newly built tunnel entrance, the tunnel is penetrated. After the tunnel is penetrated, the surrounding soil is reinforced with horizontal MJS piles to form a water-stop closed loop, and the reserved steel casing is overlapped with the annular steel plate of the reserved section; S7: After the newly built section is connected, the abandoned section is divided into compartments and partition walls are built, and fillers are poured into the top shaft to seal it; S8: Remove the retaining piles and lightweight concrete of the retained section, dismantle the steel arch frame, weld the inner lining steel casing to the inner wall steel plate of the tunnel, and then backfill to the designed ground.

2. A method for constructing a conversion well for an existing tunnel according to claim 1, characterized in that: In step S2, the grouting of the tunnel is used to offset the impact of the retaining pile construction on the retained section and abandoned section of the tunnel, and the temporary blocking parts of the retained section and abandoned section of the tunnel cannot be grouted.

3. The method for constructing a tunnel rerouting shaft according to claim 1, characterized in that: In step S3, the horizontal spacing of the steel arches is 2 meters, and the I-beams of the steel arches are connected by full penetration fillet welds.

4. The method for constructing a tunnel rerouting shaft according to claim 1, characterized in that: In step S4, the retaining piles are constructed using full-casing rotary drilling rig interlocking piles. Before construction, the soil within a certain range outside the tunnel entrance is reinforced by grouting, and a water-stop curtain is arranged at the tunnel entrance. When the retaining piles, water-stop curtain and tunnel entrance soil reinforcement meet the specified age and strength requirements, foundation pit excavation begins.

5. The method for constructing a conversion well for an existing tunnel according to claim 1, characterized in that: In step S5, the steel casing reserved in the lining wall of the conversion shaft is overlapped with the annular steel plate pre-buried in the tunnel retention section and sealed with expansive concrete.

6. The method for constructing a tunnel rerouting shaft according to claim 1, characterized in that: In step S6, the tunnel penetration construction is carried out by using the drilling and blasting method, the pipe jacking method or the shield method.

7. The method for constructing a conversion well for an existing tunnel according to claim 1, characterized in that: In step S7, the section to be blocked is divided into compartments by building partition walls, and vertical shafts are formed by drilling holes at the tops of the compartments, and the fillers are directly poured into the tunnel from the vertical shafts.

8. The method for constructing a conversion well for an existing tunnel as claimed in claim 1, characterized in that: In step S8, the steel casing provided on the inner lining wall is welded to the existing tunnel inner wall steel plate and then sealed with expansive concrete, and water-stopping measures are taken. After the construction of the new tunnel is completed, the land around the reserved section of the tunnel is reinforced using the MJS method to form a water-stopping closed loop.

9. An existing tunnel rerouting shaft, characterized in that: The conversion well connects the tunnel retention section and the abandoned section and performs temporary plugging, including retaining piles, lining structures and reinforcement structures. The retaining piles are used to protect the foundation pit and are constructed by full-casing rotary drilling rig bite piles. The pile body penetrates the existing tunnel retention section and is embedded in the bedrock. The lining structure is arranged in the foundation pit, including the wall panels and top plates of the reserved opening casing. The casing is overlapped with the newly built tunnel by annular steel plates; the reinforcement structure includes grouting reinforcement of the soil outside the newly built tunnel opening and MJS method piles to reinforce the soil around the tunnel to form a water-stop closed loop.

10. The existing tunnel rerouting and conversion shaft according to claim 9, characterized in that: The interface between the tunnel retention section and the conversion shaft is provided with a steel arch frame and filled with lightweight concrete. The abandoned blocking area is provided with a masonry partition wall to divide the compartments, and fillers are poured into the compartments.

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