A structure of a newly-built river channel underpassing an operating railway roadbed in a coastal soft soil area

Abstract

The utility model relates to a structure of new river channel underpassing operation railway subgrade in coastal soft soil area, including jacking working pit and the convenient beam support structure for the temporary support operation railway, wherein the jacking working pit has prefabricated new frame bridge, and the new frame bridge is segmented prefabricated according to different box body, and the jacking working pit is provided with internal support structure, and the internal support structure includes at least two kinds of systems, and the two kinds of systems are converted according to the jacking working condition of different box body. The utility model has the advantages of strong practicability, solves the technical problem of fast and safe jacking of large volume box body in large area deep foundation pit of coastal soft soil area adjacent to existing operation railway under the condition of surrounding environment and land use limitation, reduces the land space and ensures the railway safety, and under the condition that the railway is erected with steel convenient beam, the lattice column conversion, internal support system conversion structure according to the jacking working condition of different box body ensure the safe jacking of the box body under the railway.

Description

Technical Field

[0001] This utility model relates to the field of construction technology for underpassing operational railways, and in particular to a structure for constructing a new river channel under the subgrade of an operational railway in a coastal soft soil area. It is mainly applied to the construction of a new river channel structure under the subgrade of a railway under conditions where railway operation is not interrupted and the surrounding environment is limited. Background Technology

[0002] With the rapid construction of numerous municipal facilities in my country, especially the increasing number of new river channel projects in southern cities with their dense river networks, the issue of new river channels crossing existing railway subgrades is inevitable due to factors such as urban integration, land scarcity, and urban landscape planning. Excavation is necessary for river channels crossing railway subgrades, which inevitably disturbs the ground and causes deformation of the railway. This deformation will ultimately be reflected on the rail surface, affecting the safety of train operations, especially for operational railways with extremely high requirements for track deformation control.

[0003] This is the first time in Shanghai that a new river channel has been constructed to pass under an operating railway in a coastal soft soil area. The coastal soft soil area has extremely poor geology and abundant groundwater. At the same time, there are many buildings near the underpass point, which limits the construction space. The maximum depth of the foundation pit is about 9 meters. The existing operating railway has strict subgrade control standards, and the foundation pit area formed by the river excavation is large, which has a significant impact on the existing railway.

[0004] When constructing a new river channel that passes under an existing railway subgrade, two options are available. First, a cast-in-place frame bridge can be constructed, requiring the railway line to be cut off on-site before construction. However, this method would disrupt railway operations, resulting in significant losses for railway transport, especially for railways with special functions, making this option impractical. Second, the existing railway subgrade can be modified by altering the railway alignment, transforming it into a railway bridge. To ensure the clearance under the modified bridge meets the requirements of the new river channel, the longitudinal profile changes drastically, causing significant impact on the railway and requiring even greater investment. This also necessitates interrupting railway operations. Summary of the Invention

[0005] The purpose of this invention is to address the shortcomings of existing technologies by providing a structure for constructing new river channels under operating railway subgrades in coastal soft soil areas. Through the design of a jacking working pit and temporary beam support structure, it solves the technical challenge of rapidly and safely jacking multi-hole, large-volume box girder bodies within large-area deep foundation pits adjacent to existing operating railways in coastal soft soil areas under conditions of limited surrounding environment and land use. This achieves the goal of constructing new river channels under existing railway subgrades. The construction is convenient and economical.

[0006] The objective of this utility model is achieved through the following technical solution: A structure for constructing a new river channel under an operational railway subgrade in a coastal soft soil area is characterized by: including a jacking working pit and a temporary beam support structure for temporarily supporting the operational railway, wherein a new frame bridge is prefabricated in the jacking working pit, the new frame bridge is prefabricated with different box girder sections, and an internal support structure is provided in the jacking working pit, the internal support structure including at least two systems, the two systems being switched according to the jacking conditions of different box girder sections.

[0007] The jacking working pit consists of working pit protective piles, backfill soil, working pit bottom slab, foundation pit retaining structure water-stop curtain, working pit anchor beam, and working pit back beam. The working pit protective piles surround the perimeter of the jacking working pit and are located around the working pit bottom slab. The foundation pit retaining structure water-stop curtain is set around the working pit protective piles. The backfill soil is set on one side behind the working pit protective piles. The working pit bottom slab is located at the bottom of the jacking working pit. The working pit anchor beam is set below the working pit bottom slab. The working pit back beam is set inside the working pit protective pile on the side adjacent to the backfill soil.

[0008] The protective piles for the working pit are formed by bored cast-in-place piles to create a closed area; the bottom slab of the working pit and the anchor beam of the working pit are made of reinforced concrete.

[0009] The internal support structure includes working pit grid columns, working pit grid column pile foundations, and working pit horizontal supports. The working pit grid column pile foundations are located inside the jacking working pit, the working pit grid columns are located on top of the working pit grid columns, and the working pit horizontal supports are located between the retaining structures of the jacking working pit.

[0010] The horizontal support of the working pit includes at least two horizontal supports arranged along the depth direction of the working pit. The horizontal supports are divided into longitudinal supports, transverse supports and diagonal braces.

[0011] The temporary beam support structure includes temporary beam piers, temporary beam strip foundation piles, temporary beam strip foundation jet grouting piles, temporary beam strip foundations, and temporary beams. The temporary beam strip foundations are set on the temporary beam strip foundation piles, the temporary piers are set on the side of the temporary beam strip foundation piles, and the temporary beams are supported between the temporary beam strip foundation piles or between the temporary beam strip foundation piles and the temporary beam piers.

[0012] The temporary support piers of the temporary beam are made of reinforced concrete; the strip foundation piles of the temporary beam are made of bored cast-in-place piles; the jet grouting piles of the strip foundation of the temporary beam are made of high-pressure jet grouting piles; the strip foundation of the temporary beam is made of reinforced concrete; and the temporary beam is made of steel.

[0013] A foundation treatment system for the new frame bridge is set up below the design and construction scope of the new frame bridge.

[0014] The advantages of this utility model are: 1) It has strong practicality and solves the technical problem of rapid and safe jacking of multi-hole large-volume box bodies in large-area deep foundation pits adjacent to existing operating railways in coastal soft soil areas under the constraints of surrounding environment and land use.

[0015] 2) A closed independent foundation pit + double-layer internal support + lattice column system is adopted as the jacking working pit to reduce the land space and ensure railway safety. At the same time, under the condition of erecting steel temporary beams, the lattice column conversion and internal support system conversion are carried out according to different box body jacking conditions to ensure the safe jacking of the box body to the bottom of the railway and achieve the purpose of building a new river channel.

[0016] 3) It is easy to construct, has little impact on the safety of existing railways, and has good results, providing new ideas and methods for new river channels to pass under the operating railway subgrade in coastal soft soil areas; it has high promotion and application value. Attached Figure Description

[0017] Figure 1 This is a plan view of the first construction step of this utility model; Figure 2 This is an elevation view of the first construction step of this utility model. Figure 1 (AA section view); Figure 3 This is a plan view of the second construction step of this utility model; Figure 4 This is an elevation view of the second construction step of this utility model. Figure 3 (AA section view); Figure 5 This is a plan view of the third construction step of this utility model; Figure 6 This is an elevation view of the third construction step of this utility model. Figure 5 (AA section view); Figure 7 This is a plan view of the fourth construction step of this utility model; Figure 8 This is an elevation view of step four of the construction of this utility model; Figure 9 This is a plan view of the railway line reinforcement in step four of the construction process of this utility model; Figure 10 This is the elevation view of the railway line reinforcement in step four of the construction process of this utility model. Figure 9 (AA section view); Figure 11 This is a plan view of step five of the construction process of this utility model; Figure 12 This is the elevation view of step five of the construction of this utility model. Figure 11 (AA section view); Figure 13 This utility model relates to a cross-sectional view of the river channel beneath the railway after its construction. Detailed Implementation

[0018] The features and other related features of this utility model will be further described in detail below with reference to the accompanying drawings and embodiments, so as to facilitate the understanding of those skilled in the art: like Figure 1-13 As shown, each marker represents: Railway line centerline 1, Design estuary line 2, Land control line 3, River channel centerline 4, Jacking pit Q1, Pit protection pile Q1-1, Pit back protection pile Q1-1-1, Pit adjacent railway side protection pile Q1-1-2, Pit protection pile along the river channel Q1-1-3, Pit back fill Q1-2, Pit bottom slab Q1-3, Pit anchor beam Q1-4, Pit back beam Q1-5, Pit lattice column Q1-6, Pit lattice column pile foundation Q1-7, First support of the pit Q1-8, Pit... First support excavation face Q1-9, second support for the working pit Q1-10, second support excavation face for the working pit Q1-11, railway north side foundation pit Q2, railway north side foundation pit protective pile Q2-1, cement mixing pile foundation reinforcement Q3, pit retaining structure water-stop curtain Q4, new frame bridge Q5, new frame bridge Q6, new frame bridge Q7, new frame bridge Q8, temporary support pier for temporary beam Q9, temporary beam strip foundation pile Q10, temporary beam strip foundation jet grouting pile Q11, temporary beam strip foundation Q12, D16m temporary beam Q13, D24m temporary beam Q14, foundation treatment for new frame bridge Q15.

[0019] Example: Figures 1 to 13 As shown in this embodiment, the construction method and structure for a newly built river channel passing under an operating railway in a coastal soft soil area include the following: First, construct protective piles Q1-1 (bored cast-in-place piles) for the working pit within the designed river channel area, lattice column pile foundations Q1-7 for the working pit, protective piles Q2-1 for the foundation pit on the north side of the railway, temporary beam strip foundation pile foundations Q10, and a water-stop curtain Q4 as the protective structure for the river channel foundation pit excavation. The foundation pit on the south side of the railway serves as the jacking working pit Q1, employing a closed and independent jacking working pit Q1, a double-layered first-stage support Q1-8 for the working pit, a second-stage support Q1-10 for the working pit, and a lattice column system composed of several working pit lattice columns Q1-6. Within the jacking working pit Q1, prefabricate the newly constructed frame bridges Q5, Q6, Q7, and Q8. Under the condition of erecting D16m temporary beams Q13 and D24m temporary beams Q14, and based on the different jacking conditions of box girder Q5, Q6, Q7, and Q8, convert the working pit lattice column Q1-6, the first support Q1-8, and the second support Q1-10 systems in the working pit. After jacking the newly constructed frame bridges Q5, Q7, Q6, and Q8 respectively, the construction of the new river channel crossing the railway is completed.

[0020] The construction location information in this embodiment includes the railway line centerline 1, the designed river mouth line 2, the land use control line 3, and the river channel centerline 4.

[0021] The jacking working pit Q1 is located on the south side of the railway and consists of working pit protective piles Q1-1 (composed of working pit back protective piles Q1-1-1, working pit adjacent to railway protective piles Q1-1-2, and working pit protective piles along the river direction Q1-1-3), working pit back fill Q1-2, working pit bottom slab Q1-3, working pit anchor beam Q1-4, working pit back beam Q1-5, working pit lattice column Q1-6, working pit lattice column pile foundation Q1-7, working pit first support Q1-8, working pit first support excavation face Q1-9, working pit second support Q1-10, working pit second support excavation face Q1-11, foundation treatment Q3, and pit retaining structure water-stop curtain Q4.

[0022] Protective piles Q1-1 for the working pit are installed around the bottom plate Q1-3 of the jacking working pit, forming a closed area using bored cast-in-place piles.

[0023] The backfill soil Q1-2 behind the working pit is set after the backfill protective pile Q1-1-1 behind the working pit, and together with the protective pile, it provides reaction force for the jacking frame used by each box body of the newly built frame bridge during jacking.

[0024] The bottom slab Q1-3 of the working pit is located under the precast new frame bridge and is a reinforced concrete structure.

[0025] The anchor beam Q1-4 of the working pit is located below the bottom plate Q1-3 of the working pit. It is a reinforced concrete structure and is integrated with the bottom plate Q1-3 of the working pit to improve the overall load-bearing performance.

[0026] The back beam Q1-5 of the working pit is a reinforced concrete structure, which is set inside the back protective pile Q1-1-1 of the working pit adjacent to the back fill Q1-2 of the working pit.

[0027] The working pit lattice column Q1-6 is a steel structure.

[0028] The working pit lattice column pile foundation Q1-7 adopts bored cast-in-place piles.

[0029] The first support of the working pit, Q1-8, consists of longitudinal support, transverse support, and diagonal bracing, all of which are concrete structures.

[0030] After excavating to 1m below the bottom surface of the first support of the working pit, Q1-9, the first support of the working pit, Q1-8, can be constructed.

[0031] The second support for the working pit, Q1-10, consists of longitudinal support, transverse support, and diagonal bracing, all of which are steel supports.

[0032] After excavating to 0.5m below the bottom surface of the second horizontal support at the excavation face Q1-11 of the working pit, the second support Q1-10 of the working pit can be constructed.

[0033] The foundation pit Q2 on the north side of the railway is set up as the jacking receiving pit on the north side of the railway, which is equivalent to the other side of the jacking working pit Q1. It consists of foundation pit protection piles Q2-1 located on the north side of the railway, cement mixing pile foundation reinforcement body Q3, and pit retaining structure water-stop curtain Q4.

[0034] The cement mixing pile foundation reinforcement body Q3 adopts cement mixing piles.

[0035] The water-stop curtain Q4 of the pit retaining structure adopts cement mixing piles.

[0036] The newly built frame bridges Q5 to Q8 all adopt reinforced concrete structures. They are first cast in place in the working pit and then pushed under the railway to support the railway load above the river.

[0037] The temporary support pier Q9 for the temporary beam is made of reinforced concrete.

[0038] The temporary beam strip foundation pile Q10 is a bored cast-in-place pile, which is set under the temporary beam strip foundation Q12.

[0039] The jet grouting pile Q11 of the temporary beam strip foundation adopts high-pressure jet grouting pile. Due to the low height of the construction equipment, the high-pressure jet grouting pile can effectively reinforce the foundation under the railway line and support the temporary beam strip foundation Q12 together with the temporary beam strip foundation pile Q10.

[0040] The Q12 strip foundation for the convenient beam is made of reinforced concrete and supports the convenient beam.

[0041] The D16m temporary beam Q13 and the D24m temporary beam Q14 are steel structures. The D16m temporary beam Q13 is supported by the temporary beam temporary support pier Q9. The D24m temporary beam Q14 is supported between the newly built temporary beam strip foundations Q12, and the 16m temporary beam Q13 is erected as a support beam. High-pressure jet grouting piles are used under the construction box body to push the box body in.

[0042] The foundation treatment of the newly built frame bridge Q15 adopts high-pressure jet grouting piles.

[0043] This embodiment can be implemented using the following steps during construction: Step 1: Construction of railway foundation reinforcement and pit retaining structure.

[0044] Step 2: Excavation of working pit Q1 and construction of the first support Q1-8: Dewatering in working pit Q1 → Excavation of working pit Q1 to 1m below the first support Q1-8 → Construction of the second, third and sixth rows of lattice columns Q1-6 → Installation of the first support Q1-8.

[0045] Step 3: Excavation of working pit Q1 and construction of the second support Q1-10 within the pit: Excavate working pit Q1 to 0.5m below the second support Q1-10 → construct the lattice column Q1-6 at the corresponding positions of the newly built frame bridge Q5 and Q7 → install the second support Q1-10.

[0046] Step 4: Excavate the jacking working pit Q1 to the bottom, reinforce the railway line, precast the new frame bridge Q5 and Q7, and jack up the new frame bridge Q5 and Q7: Excavate the jacking working pit Q1 to the bottom elevation → pour the working pit bottom slab Q1-3, the working pit anchor beam Q1-4 and the working pit back beam Q1-5 → erect the D16m temporary beam Q13, construct the temporary beam strip foundation Q12 under the temporary beam strip foundation jet grouting pile Q11 → pour the temporary beam strip foundation Q12 and the temporary beam temporary support Q9 → erect D24 The temporary beam Q14 is placed on the strip foundation Q12, and the D16m temporary beam Q13 is erected as a support beam → Construction of the new frame bridge Q5 and the new frame bridge Q7 under the new frame bridge foundation treatment body Q15 (high pressure jet grouting pile) → After the bottom plate Q1-3 of the working pit and the anchor beam Q1-4 of the working pit reach 100% of the design strength, the second support Q1-10 of the working pit is removed → The new frame bridge Q5 and the new frame bridge Q7 are jacked into the working pit → The new frame bridge Q5 and the new frame bridge Q7 are jacked into the design position.

[0047] Step 5: Conversion of the support system within the jacking working pit Q1; prefabrication of the new frame bridges Q6 and Q8; jacking of the new frame bridges Q6 and Q8: construction of the lattice columns Q1-6 corresponding to the new frame bridges Q6 and Q8, fixing the top of each lattice column to the first support Q1-8 of the working pit → removal of the lattice columns constructed in the previous steps → replacement of the box girder (D16m girder Q13, D24m girder Q14) positions → construction of the foundation treatment body Q15 (high-pressure jet grouting piles) for the new frame bridges Q6 and Q8 under the railway → prefabrication of the new frame bridges Q6 and Q8 within the jacking working pit Q1 → jacking of the new frame bridges Q6 and Q8 to the designed positions → removal of each girder (D16m girder Q13, D24m girder Q14), restoring the railway traffic conditions on the jacking section.

[0048] The structure provided in this implementation for a new river channel passing under an operating railway subgrade in a coastal soft soil area solves the technical challenge of rapidly and safely jacking up a multi-hole, large-volume box girder within a large-area deep foundation pit adjacent to an existing operating railway in a coastal soft soil area under conditions of limited surrounding environment and land use. It has good technical and economic efficiency, significant social benefits, and broad application prospects.

[0049] 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 structure for a newly constructed river channel passing under an operational railway subgrade in a coastal soft soil area, characterized in that: The system includes a jacking pit and a temporary beam support structure for supporting the operating railway. A new frame bridge is prefabricated within the jacking pit, with different box girder sections prefabricated. An internal support structure is installed within the jacking pit, comprising at least two systems that can be switched according to the jacking conditions of different box girder sections. The jacking pit consists of protective piles, backfill, a bottom slab, a water-stop curtain for the pit's retaining structure, anchor beams, and a back beam. The protective piles surround the jacking pit and are located around the bottom slab. The water-stop curtain is positioned around the protective piles. The backfill is located on one side behind the protective piles. The bottom slab is located at the bottom of the jacking pit. The anchor beams are located below the bottom slab. The back beams are located inside the protective piles on the side adjacent to the backfill.

2. The structure for a newly constructed river channel passing under an operational railway subgrade in a coastal soft soil area according to claim 1, characterized in that: The protective piles for the working pit are formed by bored cast-in-place piles to create a closed area; the bottom slab of the working pit and the anchor beam of the working pit are made of reinforced concrete.

3. The structure for a newly constructed river channel passing under an operational railway subgrade in a coastal soft soil area according to claim 1, characterized in that: The internal support structure includes working pit grid columns, working pit grid column pile foundations, and working pit horizontal supports. The working pit grid column pile foundations are located inside the jacking working pit, the working pit grid columns are located on top of the working pit grid columns, and the working pit horizontal supports are located between the retaining structures of the jacking working pit.

4. The structure for a newly constructed river channel passing under an operational railway subgrade in a coastal soft soil area according to claim 3, characterized in that: The horizontal support of the working pit includes at least two horizontal supports arranged along the depth direction of the working pit. The horizontal supports are divided into longitudinal supports, transverse supports and diagonal braces.

5. The structure for a newly constructed river channel passing under an operational railway subgrade in a coastal soft soil area according to claim 1, characterized in that: The temporary beam support structure includes temporary beam piers, temporary beam strip foundation piles, temporary beam strip foundation jet grouting piles, temporary beam strip foundations, and temporary beams. The temporary beam strip foundations are set on the temporary beam strip foundation piles, the temporary piers are set on the side of the temporary beam strip foundation piles, and the temporary beams are supported between the temporary beam strip foundation piles or between the temporary beam strip foundation piles and the temporary beam piers.

6. The structure for a newly constructed river channel passing under an operational railway subgrade in a coastal soft soil area according to claim 5, characterized in that: The temporary support piers of the temporary beam are made of reinforced concrete; the strip foundation piles of the temporary beam are made of bored cast-in-place piles; the jet grouting piles of the strip foundation of the temporary beam are made of high-pressure jet grouting piles; the strip foundation of the temporary beam is made of reinforced concrete; and the temporary beam is made of steel.

7. The structure for a newly constructed river channel passing under an operational railway subgrade in a coastal soft soil area according to claim 1, characterized in that: A foundation treatment system for the new frame bridge is set up below the design and construction scope of the new frame bridge.

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