Construction method for closed caisson after leaving a groove for cross pipelines

Abstract

The present invention relates to a construction method for a closed caisson after leaving a groove for a cross pipeline, which includes steps: suspension protection of existing pipelines, excavation construction of a shallow working pit, construction of a water-stop curtain, in-situ casting construction of a cutting edge, symmetric hoisting and lowering construction of the well walls on both sides of the cross pipeline, and concrete bottom sealing construction. The beneficial effects of the present invention are as follows: By means of the combined measures of integral in-situ casting of the cutting edge under the existing pipeline, prefabrication of the well walls in sections and symmetric hoisting with the existing pipeline as the axis, post-pouring and closing of the groove opening, and water-stop protection, the practical problem that the current precast caisson cannot cross the existing underground pipeline is solved; the closed groove opening is gradually closed during the lowering of the caisson unit, effectively shortening the exposure time of the groove opening in each section; reducing the workload of slope excavation and support, and also improving the construction efficiency of the caisson construction.

Description

Technical Field

[0001] The present invention relates to a construction method for closing a caisson after leaving a groove for a cross - pipeline, which is applicable to the construction of a caisson crossing underground pipelines, and is particularly applicable to the construction of closing a caisson after leaving a groove for a cross - pipeline. Background Art

[0002] The caisson construction of culverts or abutments usually takes precast unit bodies as the main part. By hoisting the caisson walls separately and excavating the soil inside the caisson, relying on the self - weight of the caisson walls to overcome the wall resistance and sink it to the designed elevation. However, in the urban environment, there are many underground structures such as underground pipelines and culverts, and their spatial distribution positions may coincide with the settlement construction positions. In this case, usually, the position of the caisson is changed to avoid these pipelines, or the positions of existing pipelines are changed or truncated to facilitate the settlement construction, or the method of cast - in - place caisson is adopted. However, in special environments and conditions, such as narrow urban spaces where the settlement position cannot be changed, or underground pipelines are particularly important and cannot be intervened, truncated or changed by administrative means. The cast - in - place caisson has a large floor area and complex support, so the cost is particularly high. Therefore, there is an urgent need for a construction method for precast caissons that can cross existing pipelines. Summary of the Invention

[0003] The purpose of the present invention is to overcome the deficiencies in the prior art and provide a construction method for closing a caisson after leaving a groove for a cross - pipeline.

[0004] This construction method for closing a caisson after leaving a groove for a cross - pipeline includes the following steps:

[0005] Step 1: Suspension protection of existing pipelines: Excavate a suspension pit at the caisson position until the existing pipelines are exposed, support suspension piers and erect Bailey beams, and suspend the existing pipelines on the Bailey beams with suspension ropes.

[0006] Step 2: Excavation construction of a shallow working pit: Slope at a certain angle below the existing pipelines and excavate the shallow working pit to a depth of 2.0 m - 2.5 m below the existing pipelines.

[0007] Step 3: Construction of a water - stop curtain: Carry out mixing pile construction on the bottom contour line of the shallow working pit, with the static distance between adjacent mixing piles being their diameter, and insert I - beams along the vertical axis of the mixing piles to form a water - stop curtain.

[0008] Step 4: Cast - in - place construction of the cutting edge: Carry out cast - in - place construction of the cutting edge at the bottom of the shallow working pit. After setting up the formwork of the cutting edge and binding the steel bars, carry out concrete pouring construction and then remove the formwork to complete the cast - in - place operation of the cutting edge.

[0009] Step 5. Symmetric hoisting and lowering construction across the well walls on both sides of the pipeline: The first section of the well wall 1 and the well wall 2 are symmetrically hoisted to the top of the blade foot with the existing pipeline as the axis of symmetry, and earth is taken simultaneously inside and outside the well to assist the well wall in sinking; a scaffolding is erected at the bottom of the open caisson, the inner formwork of the notch is set, the transverse tie bars and longitudinal bars of the notch are tied, the outer formwork of the notch is set and the concrete is poured, and then the outer formwork of the notch is removed; the well wall segments are repeatedly hoisted and placed until the open caisson sinks to the designed height;

[0010] Step 6. Concrete bottom sealing construction: Concrete bottom sealing construction is carried out at the blade foot, and after leaving a slot for the cross pipeline, the construction of the closed open caisson is completed.

[0011] Preferably: During the operation inside the open caisson, the tops of workers, facilities and equipment, and the structure all maintain a construction safety static distance of 0.3 m to 0.5 m from the bottom sides of the existing pipeline.

[0012] Preferably, in Step 1: The excavation width of the suspension pit is 2.0 to 3.0 times the diameter of the existing pipeline, the excavation depth of the suspension pit is the same as that of the existing pipeline, and the excavation length of the suspension pit is the same as the suspension length of the existing pipeline; the suspension length of the existing pipeline is the top length of the shallow working pit of the cross pipeline.

[0013] Preferably, in Step 3: The diameter of the formed mixing pile is larger than the diameter of the existing pipeline and the width of the Bailey beam, and the depth of the water-stop curtain exceeds the designed depth of the open caisson by 2.5 m to 3.0 m.

[0014] Preferably, in Step 5: The well wall 1 and the well wall 2 are used as the prefabricated hoisting and placing units of the open caisson, the height of each unit is controlled within 2.0 to 3.0 times the height of the blade foot, connecting bars are provided on the inner side walls of the well wall 1 and the well wall 2, and they are hoisted and placed with the existing pipeline as the axis of symmetry. The width of the formed notch is larger than the larger value of the diameter of the existing pipeline and the width of the Bailey beam. The two ends of the transverse tie bars are respectively welded to connect the connecting bars of the well wall 1 and the well wall 2, and then longitudinal bars are tied to the transverse tie bars. The longitudinal bars are arranged longitudinally and continuously in sections along the notch, and the longitudinal bars are connected by welding.

[0015] Preferably, in Step 5: The pouring height of the concrete is the same as the sinking height of the well wall, and the concrete solidifies and hardens to form a closed notch.

[0016] Preferably, in Step 6: The thickness of the concrete bottom sealing is greater than or equal to the height of the blade foot.

[0017] An open caisson closed after leaving a slot for a cross pipeline, obtained by any of the above methods.

[0018] The beneficial effects of the present invention are:

[0019] 1) The present invention has developed a construction method for a closed caisson after leaving a slot across pipelines by means of a combination of measures such as integrally cast-in-place cutting edges below existing pipelines, prefabricating the well walls separately and symmetrically hoisting them with the existing pipelines as the axis, pouring and sealing the slot openings later, and water-stop protection, which solves the practical problem that current precast caissons cannot cross existing underground pipelines and has significant technical advantages.

[0020] 2) The closed slot openings of the present invention are gradually closed during the lowering of the caisson units, effectively shortening the exposure time of the slot openings in each section and improving the quality of caisson construction, having certain technical advantages.

[0021] 3) Compared with the method of cast-in-place caissons crossing existing underground pipelines, the present invention not only reduces the workload of slope excavation and support, but also improves the work efficiency of caisson construction, having outstanding economic benefits. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 is a schematic cross-sectional view of the excavation of the suspension pit;

[0023] Figure 2 is a schematic cross-sectional view of the suspension and protection of existing pipelines;

[0024] Figure 3 is a schematic cross-sectional view of the excavation of the shallow working pit;

[0025] Figure 4 is a schematic cross-sectional view of the construction of the water-stop curtain;

[0026] Figure 5 is a schematic plan view of the construction of the water-stop curtain;

[0027] Figure 6 is a schematic cross-sectional view of the cast-in-place construction of the cutting edge;

[0028] Figure 7 is a schematic plan view of the cast-in-place construction of the cutting edge;

[0029] Figure 8 is a schematic cross-sectional view of the symmetrical hoisting of the first-section well wall;

[0030] Figure 9 is a schematic plan view of the symmetrical hoisting of the first-section well wall;

[0031] Figure 10 is a schematic cross-sectional view of the symmetrical lowering of the first-section well wall;

[0032] Figure 11 is a schematic cross-sectional view of the construction of the closed slot opening of the first-section well wall;

[0033] Figure 12 is a side view of the construction of the closed slot opening of the first-section well wall;

[0034] Figure 13 is isFigure 12 Cross-section view A-A in

[0035] Figure 14 It is a schematic diagram of the symmetric hoisting cross-section of the wellbore of other segments;

[0036] Figure 15 It is a schematic diagram of the symmetric lowering cross-section of the wellbore of other segments;

[0037] Figure 16 It is a schematic diagram of the construction cross-section of the closed notch of the wellbore of other segments;

[0038] Figure 17 It is a construction cross-section view of the concrete bottom seal;

[0039] Figure 18 It is a process flow diagram of the construction of the closed caisson after leaving a slot for the cross-pipeline.

[0040] Explanation of reference numerals: 1 - Suspension pit; 2 - Existing pipeline; 3 - Suspension rope; 4 - Suspension pier; 5 - Bailey beam; 6 - Ground; 7 - Shallow working pit; 8 - Cut-off curtain; 81 - Mixing pile; 82 - I-beam; 9 - Cutting edge; 10 - Wellbore; 101 - First wellbore; 102 - Second wellbore; 11 - Notch; 12 - Connecting reinforcement; 13 - Closed notch; 14 - Concrete bottom seal; 15 - Scaffold; 16 - Transverse tie reinforcement; 17 - Longitudinal reinforcement; 18 - Inner formwork of the notch; 19 - Outer formwork of the notch. Detailed implementation manners

[0041] The present invention will be further described below in conjunction with embodiments. The description of the following embodiments is only for helping to understand the present invention. It should be noted that for those of ordinary skill in the art, without departing from the principle of the present invention, several modifications can be made to the present invention, and these improvements and modifications also fall within the protection scope of the claims of the present invention.

[0042] Embodiment 1

[0043] As an embodiment, refer to Figures 1 to 18 , a construction method for closing a caisson after leaving a slot for a cross-pipeline, specifically including the following implementation steps:

[0044] Step 1. Suspension protection of existing pipelines: On the ground 6, moderately excavate the suspension pits 1 on both sides of the existing pipelines 2 crossing the caisson, and expose the existing pipelines 2 to be suspended. The excavation width of the suspension pit 1 is 2.0 - 3.0 times the diameter of the existing pipeline 2. The excavation depth of the suspension pit 1 is the same as that of the existing pipeline 2, and the excavation length of the suspension pit 1 is the same as the suspension length of the existing pipeline 2. The suspension length of the existing pipeline 2 is the top length of the shallow working pit 7 of the crossing pipeline. The suspension piers 4 are arranged outside the shallow working pit 7 and reinforced. The Bailey beam 5 is erected through the suspension piers 4, and the existing pipeline 2 is suspended on the Bailey beam 5 by tying with the suspension ropes 3 to complete the suspension protection of the existing pipeline 2.

[0045] Step 2. Excavation construction of the shallow working pit: After the suspension protection of the existing pipeline 2 is completed, slope downwards at a certain angle along the excavation line at the top of the shallow working pit 7 from top to bottom until reaching the bottom of the shallow working pit 7. The bottom of the shallow working pit 7 is below the existing pipeline 2, and the static distance from its depth to the existing pipeline 2 is 2.0 m - 2.5 m to facilitate other construction operations of workers and equipment in the later stage.

[0046] Step 3. Construction of the water-stop curtain: After the excavation of the shallow working pit 7 is completed, construct the mixing piles 81 along the bottom contour line of the shallow working pit 7. The diameter of the formed mixing piles 81 is greater than the larger value of the diameter of the existing pipeline 2 and the width of the Bailey beam 5 to facilitate the construction operation of the mixing piles 81. The static distance between adjacent mixing piles 81 is its diameter. Immediately insert the I-beams 82 along the vertical axis of the mixing piles 81 to form a water-stop curtain 8 similar to the SMW method pile, and its depth exceeds the designed depth of the caisson by 2.5 m - 3.0 m.

[0047] Step 4. In-situ casting construction of the cutting edge: After the water-stop curtain 8 is completed, carry out the in-situ casting construction of the cutting edge 9 at the bottom of the shallow working pit 7. The outer diameter of the cutting edge 9 is the same as the inner length of the water-stop curtain 8, and the height of the cutting edge 9 is controlled within 1.5 m - 2.0 m. After erecting the formwork for the cutting edge 9 and tying the steel bars for the cutting edge 9, carry out the concrete pouring construction. After the concrete hardens, remove the formwork for the cutting edge 9 to complete the in-situ casting operation of the cutting edge 9.

[0048] Step 5. Symmetric hoisting and lowering construction of the well walls on both sides of the crossing pipeline: The well wall 101 and the well wall 102 are used as the precast hoisting and lowering units of the caisson. The height of each unit is controlled within 2 - 3 times the height of the cutting edge 9. Connecting bars 12 are provided on the inner side walls of the well wall 101 and the well wall 102, and they are hoisted with the existing pipeline 2 as the axis of symmetry. The width of the formed notch 11 is greater than the larger value of the diameter of the existing pipeline 2 and the width of the Bailey beam 5. Its construction steps are as follows:

[0049] 5.1 Symmetric hoisting of the well wall: The first section of the well wall - 101 and the second section of the well wall - 102 are symmetrically hoisted to the top of the cutting edge 9 with the existing pipeline 2 as the axis of symmetry. Under the self-weight of the well wall 10, the cutting edge 9 starts to sink, and synchronous soil excavation inside and outside the well is carried out to assist, so that the sinking height of the well wall 10 is consistent with its unit height;

[0050] 5.2 Construction of the closed notch: Scaffolding 15 is erected synchronously at the bottom of the open caisson, the inner formwork 18 of the notch is set, the transverse tie bars 16 and longitudinal bars 17 of the notch 11 are tied, and then the outer formwork 19 of the notch is set and concrete is poured. The pouring height is consistent with the sinking height of the well wall 10. After the concrete solidifies and hardens, the outer formwork 19 of the notch is removed, while the inner formwork 18 of the notch is retained to form the closed notch 13;

[0051] 5.3 Hoisting of other sections of the well wall: Repeat steps 5.1 and 5.2, hoist other sections of the well wall 10 accordingly, and recover the scaffolding 15 and outer formwork used in the construction to complete the symmetric hoisting and lowering of the well walls 10 on both sides of the cross-pipeline.

[0052] Step Six: Concrete bottom sealing construction: After the open caisson sinks to the designed height, concrete bottom sealing 14 construction is carried out at the cutting edge 9. The thickness of the concrete bottom sealing 14 should not be less than the height of the cutting edge 9, so as to complete the construction operation of closing the open caisson after leaving a groove for the cross-pipeline.

[0053] During the specific implementation process, a construction safety static distance of about 0.3m - 0.5m needs to be maintained between the workers, facilities and equipment inside the open caisson, the top of the structure and the bottom and side of the existing pipeline 2.

[0054] Both ends of the transverse tie bars 16 are welded to the connecting bars 12 of the first section of the well wall - 101 and the second section of the well wall - 102. The longitudinal bars 17 are tied to the transverse tie bars 16 and are arranged longitudinally and continuously along the longitudinal length of the notch 11. Welding is carried out between each section of the longitudinal bars 17.

[0055] Embodiment Two

[0056] As another embodiment, according to the construction method of closing the open caisson after leaving a groove for the cross-pipeline proposed in Embodiment One, an open caisson after leaving a groove for the cross-pipeline is as Figures 1 to 17 shown, including: existing pipeline 2, shallow working pit 7, water-stop curtain 8, cutting edge 9, well wall 10 and closed notch 13; There is a suspension pit 1 on the ground 6, and the suspended section of the existing pipeline 2 is exposed in the suspension pit 1; On the ground 6 outside the suspension pit 1, a Bailey beam 5 is provided through suspension piers 4. The Bailey beam 5 is parallel to the existing pipeline 2 and is arranged directly above the existing pipeline 2. The Bailey beam 5 is connected to the existing pipeline 2 through a suspension rope 3 to complete the suspension protection of the existing pipeline 2; The width of the suspension pit 1 is 2.0 - 3.0 times the diameter of the existing pipeline 2. The depth of the suspension pit 1 is consistent with the bottom elevation of the existing pipeline 2, and the length of the suspension pit 1 is consistent with the length of the suspended section of the existing pipeline 2.

[0057] The shallow working pit 7 is provided below the existing pipeline 2; the bottom of the shallow working pit 7 is a plane, and the static distance between the bottom plane of the shallow working pit 7 and the existing pipeline 2 is 2.0 m to 2.5 m, so as to facilitate the operation and construction of workers and equipment; the top excavation line of the shallow working pit 7 slopes at a certain angle to the bottom plane. A water-stop curtain 8 is provided along the bottom contour of the shallow working pit 7 in the soil body below the shallow working pit 7. The water-stop curtain 8 is composed of adjacent mixing piles 81 connected together. The bottom depth of the water-stop curtain 8 exceeds the designed depth of the caisson by 2.5 m to 3.0 m. The diameter of the mixing pile 81 is larger than the widths of the existing pipeline 2 and the Bailey beam 5. An I-beam 82 is provided on the vertical axis in the mixing pile 81;

[0058] The outer diameter of the cutting edge 9 is the same as the inner length of the water-stop curtain 8; the well wall 10 includes a first well wall 101 and a second well wall 102. The first well wall 101 and the second well wall 102 are symmetrically arranged above the cutting edge 9 along the existing pipeline 2, and there is a gap between the first well wall 101 and the second well wall 102 to form a notch 11. The width of the notch 11 is larger than the widths of the existing pipeline 2 and the Bailey beam 5; a closed notch 13 is provided at the notch 11 of the first well wall 101 and the second well wall 102;

[0059] The closed notch 13 includes transverse tie bars 16 and longitudinal bars 17. The transverse tie bars 16 are arranged in the notch 11. The two ends of the transverse tie bars 16 are respectively connected to the connecting bars 12 of the first well wall 101 and the second well wall 102. Longitudinal bars 17 are provided between the transverse tie bars 16. An inner formwork 18 for the notch is provided on the outer side of the well wall 10, and an outer formwork 19 for the notch is provided on the inner side of the well wall 10.

[0060] The height of the cutting edge 9 is 1.5 m to 2.0 m. A concrete bottom seal 14 is provided inside the cutting edge 9, and the thickness of the concrete bottom seal 14 is greater than the height of the cutting edge 9. The heights of the first well wall 101 and the second well wall 102 are 2 to 3 times that of the cutting edge 9.

Claims

1. A construction method for a closed caisson after leaving a groove for a cross pipeline, characterized in that, It includes the following steps: Step 1. Suspension protection of existing pipelines: Excavate a suspension pit (1) at the caisson location until the existing pipeline (2) is exposed, support suspension piers (4) and erect Bailey beams (5), and use suspension ropes (3) to suspend the existing pipeline (2) on the Bailey beams (5); Step 2. Excavation construction of the shallow working pit: Slope down at a certain angle below the existing pipeline (2), and excavate the shallow working pit (7) to a depth of 2.0 m to 2.5 m below the existing pipeline (2); Step 3. Construction of the water-stop curtain: Construct mixing piles (81) along the bottom contour line of the shallow working pit (7), with the static distance between adjacent mixing piles (81) being their diameter, and insert I-beams (82) along the vertical axis of the mixing piles (81) to form a water-stop curtain (8); Step 4. In-situ casting construction of the cutting edge: Conduct in-situ casting construction of the cutting edge (9) at the bottom of the shallow working pit (7). After erecting the formwork of the cutting edge (9) and tying the steel bars, conduct concrete pouring construction and then remove the formwork to complete the in-situ casting operation of the cutting edge (9); Step 5. Symmetric hoisting and lowering construction of the well walls on both sides of the cross pipeline: The first section of well wall one (101) and well wall two (102) are symmetrically hoisted to the top of the cutting edge (9) with the existing pipeline (2) as the axis of symmetry, and soil is taken simultaneously inside and outside the well to assist the well wall (10) in sinking; Erect a scaffold (15) at the bottom of the caisson, set the inner formwork (18) of the notch, tie the transverse connecting bars (16) and longitudinal bars (17) of the notch (11), set the outer formwork (19) of the notch and pour concrete, and then remove the outer formwork (19) of the notch; Repeat the hoisting and lowering of the well wall (10) segments until the caisson sinks to the designed height; The height of each unit is controlled within 2.0 to 3.0 times the height of the cutting edge (9). Connecting bars (12) are provided on the inner side walls of both well wall one (101) and well wall two (102), and they are hoisted with the existing pipeline (2) as the axis of symmetry. The width of the formed notch (11) is greater than the larger value of the diameter of the existing pipeline (2) and the width of the Bailey beam (5); Step 6. Concrete bottom sealing construction: Conduct concrete bottom sealing (14) construction at the cutting edge (9), and complete the construction of closing the caisson after leaving a groove for the cross pipeline; 2. The construction method of the open caisson after leaving a groove for the cross pipeline according to claim 1, characterized in that: During the operation inside the caisson, there is a construction safety clearance of 0.3 m to 0.5 m between the top of the workers, facilities and equipment, and the structure and each side of the bottom of the existing pipeline (2).

3. The construction method of the open caisson after crossing pipelines with grooves left and then closed according to claim 1, characterized in that, In Step 1: The excavation width of the suspension pit (1) is 2.0 to 3.0 times the diameter of the existing pipeline (2), the excavation depth of the suspension pit (1) is the same as that of the existing pipeline (2), and the excavation length of the suspension pit (1) is the same as the suspension length of the existing pipeline (2); The suspension length of the existing pipeline (2) is the top length of the shallow working pit (7) of the cross pipeline.

4. The construction method of the open caisson after leaving a groove for the cross pipeline according to claim 1, characterized in that, In Step 3: The diameter of the formed mixing piles (81) is greater than the diameter of the existing pipeline (2) and the width of the Bailey beam (5), and the depth of the water-stop curtain (8) exceeds the designed depth of the caisson by 2.5 m to 3.0 m.

5. The construction method of the open caisson after leaving a groove for the cross pipeline according to claim 1, characterized in that In Step Five: The first well wall (101) and the second well wall (102) serve as the prefabricated hoisting units of the open caisson. The two ends of the transverse tie bars (16) are respectively welded to the connecting bars (12) of the first well wall (101) and the second well wall (102), and then the longitudinal bars (17) are tied to the transverse tie bars (16). The longitudinal bars (17) are longitudinally arranged in segments along the notch (11) and are connected by welding between the longitudinal bars (17).

6. The construction method of the open caisson after crossing pipelines with grooves left and then closed according to claim 1, characterized in that, In Step Five: The pouring height of the concrete is consistent with the sinking height of the well wall (10), and the concrete solidifies and hardens to form a closed notch (13).

7. The construction method of the open caisson after crossing pipelines with grooves left and then closed according to claim 1, characterized in that, In Step Six: The thickness of the concrete bottom seal (14) is greater than or equal to the height of the cutting edge (9).

8. A closed caisson after leaving a groove for a cross pipeline, characterized in that: Obtained by the method according to any one of Claims 1 to 7.

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