Foundation pit supporting device of inspection well in limited space and inspection well operation method

Abstract

According to the foundation pit supporting device of the inspection well in the limited space and the inspection well operation method, the multiple pile casings are stacked to form a support, and the overall structure is convenient and fast. During use, channel steel is matched with a cable to hoist each pile casing, and meanwhile, an external hoisting device is used to hoist the bottom pile casing all the time, so that collapse of a foundation pit in a limited space is prevented, the safety is further improved, meanwhile, it is guaranteed that inspection well operation is not limited by the space, and the inspection well can also be used in a narrow space and is suitable for large-scale industrial use and popularization.

Description

Technical Field

[0001] This invention belongs to the field of urban water environment management, specifically relating to a pit support device for confined space inspection wells and an inspection well operation method. Background Technology

[0002] The construction of urban drainage pipelines is an important municipal project for urban water environment management. In the construction of drainage pipelines, inspection wells, as ancillary structures, play an important role in maintenance and repair.

[0003] Inspection wells are mostly circular in shape. As the depth of drainage pipes gradually increases, the depth of drainage inspection wells also increases. Since drainage inspection wells are mostly located on the green belts or sidewalks on both sides of the road, their width is limited. Therefore, during the excavation of the foundation pit, the excavation size is affected by the road width, making it difficult to use a slope excavation method. Especially for inspection wells with a depth greater than 3m, support measures must be taken for the foundation pit excavation, which greatly increases the construction difficulty of the inspection well.

[0004] Existing support technologies include Larssen sheet pile support, shotcrete support, and inverted wall support; all of these methods suffer from cumbersome structures and are unsuitable for confined environments. Summary of the Invention

[0005] The purpose of this invention is to provide a foundation pit support device and a method for operating inspection wells in confined spaces, so as to solve the problem that the support devices in the prior art are cumbersome in structure and unsuitable for confined environments.

[0006] To solve the above-mentioned technical problems, the present invention adopts the following technical solution: A foundation pit support device for a confined space inspection well includes a support assembly disposed inside the foundation pit; the support assembly includes multiple upper casings and a bottom casing that are vertically connected end to end. Multiple retaining rings are evenly fixed along the circumference of the upper inner wall of the upper protective casing. The upper part of the retaining ring protrudes from the upper end of the upper protective casing, and the protruding part of the retaining ring is inclined inward. The bottom protective sleeve has the same structure as the upper protective sleeve, and the bottom of the bottom protective sleeve has arc-shaped slots on both sides. A channel steel is erected on each of the opposite sides of the top of the foundation pit; the middle of the channel steel is fixedly connected to one end of at least one cable, and the other end of the cable can hold the retaining ring of the bottom casing.

[0007] The present invention also has the following features: Furthermore, the channel steel is also fixedly connected with a number of cables equal to the number of upper protective casings, and the other ends of these cables can be used to suspend the retaining rings of each upper protective casing.

[0008] Furthermore, the retaining ring is made of HPB300Φ14 steel bar bent into an arch shape, and the bottom two ends of the retaining ring are fixedly connected to the upper inner wall of the upper casing. The upper protective casing is made of 10mm thick steel plate.

[0009] Furthermore, the arch of the retaining ring protrudes 15cm from the upper protective sleeve, and the protruding part of the retaining ring is inclined inward at an angle of 15°. The distance between two adjacent retaining rings is 500mm.

[0010] Furthermore, the upper casing has a height of 1.5m, an ellipticity of less than d / 100, a maximum allowable deviation of the casing surface inclination of less than 3mm, and a longitudinal axis bending sag of no more than 0.1% of the upper casing height. A method for operating a manhole, based on the aforementioned manhole pit support device, includes the following steps: Step 0: Drill a directional borehole and lower the drainage pipe into it; delineate a circular area on the ground corresponding to the location of the drainage pipe as the work area, and determine the foundation bottom elevation of the inspection well according to actual needs; Step 1: Make the inner diameter of the foundation pit larger than the diameter of the defined circular area, and use an excavation device to carry out the first excavation. The bottom of the foundation pit is located above the drainage pipe. Step 2: The pit is excavated a second time by manual labor until the upper part of the drainage pipe is exposed; Step 3: Use an external hoisting device to lift the retaining ring of the bottom casing and lower the bottom casing into the pit, so that the retaining groove at the bottom of the bottom casing is engaged with the upper part of the drainage pipe. Step 4: Level the bottom casing to ensure that the verticality deviation is no more than 1%. Set up two channel steels at the top of the pit and then use the corresponding cables to suspend the retaining rings on both sides of the bottom casing. Step 5: Use external hoisting equipment to continue lowering the upper casing until the support assembly is formed. Use cables to suspend the retaining rings of each upper casing one by one. Step 6: The foundation pit is manually excavated for the third time, down to the foundation bottom elevation; the excavation area during the third excavation is reduced inward, and the diameter of the reduced excavation area is not less than the diameter of the inspection well. Step 7: Construct inspection wells coaxially within the support components until the inspection wells are completed; Step 8: Use external hoisting equipment to lift out the upper and lower casing sections from top to bottom to complete the manhole foundation pit support; Backfill the annular space between the outer wall of the manhole and the foundation pit, and seal the manhole opening with a manhole cover to complete the overall operation.

[0011] Furthermore, in step 1, during the initial excavation, the bottom of the pit is positioned 150mm above the drainage pipe; In step 2, during the second excavation, the upper part of the drainage pipe should be exposed by more than 150mm.

[0012] Furthermore, in step 6, the excavated circumferential area is reduced inward by 50mm.

[0013] Furthermore, in step 7, when constructing the inspection well coaxially within the support assembly, the distance between the outer wall of the inspection well and the inner wall of the support assembly shall not be less than 15cm.

[0014] Furthermore, before the manhole is completed, the external hoisting device always holds the retaining ring of the bottommost upper casing.

[0015] Compared with the prior art, the present invention has the following technical effects: The confined space inspection well pit support device and inspection well operation method of the present invention form a support by stacking multiple casings, and the overall structure is convenient. In use, each casing is suspended by channel steel and cable, and an external hoisting device is used to keep the bottom casing suspended at all times to prevent the pit from collapsing in the confined space. This further improves safety and ensures that the inspection well operation is not limited by space. It can be used even in narrow spaces and is suitable for large-scale industrial use and promotion. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of the overall structure of the pit support device for the confined space inspection well of the present invention; Figure 2 This is a schematic diagram of the protective sleeve structure in this invention; Figure 3 This is a schematic diagram of the structure of the bottommost casing of the support assembly in this invention; Figure 4 This is a schematic diagram of the retaining ring structure in this invention; Figure 5 This is a top view of the confined space inspection well foundation pit support device of the present invention entering the foundation pit; Figure 6 This is a cross-sectional view of the foundation pit support device for the confined space inspection well of the present invention entering the foundation pit; Figure 7 This is a cross-sectional view of the state after the support components are removed and the inspection well is backfilled in one embodiment of the present invention.

[0017] The meanings of the labels in the diagram are as follows: 1. Upper casing; 2. Snap ring; 3. Snap groove; 4. Channel steel; 5. Cable; 6. Foundation pit; 7. Bottom casing; 8. Drainage pipe. Detailed Implementation

[0018] It should be noted that, unless otherwise specified, all components in this invention are known in the prior art. For example, the hoisting device uses a commonly known hoisting device.

[0019] The following are specific embodiments of the present invention. It should be noted that the present invention is not limited to the following specific embodiments. All equivalent modifications made based on the technical solutions of this application fall within the protection scope of the present invention.

[0020] like Figures 1 to 4 As shown, a foundation pit support device for a confined space inspection well includes a support assembly; the support assembly includes multiple upper casings 1 and a bottom casing 7 that are vertically connected end to end. Multiple retaining rings 2 are evenly fixed along the circumference of the upper inner wall of the upper casing 1. The upper part of the retaining ring 2 protrudes from the upper end of the upper casing 1, and the protruding part of the retaining ring 2 is inclined inward. The bottom casing 7 has the same structure as the upper casing 1. The bottom of the bottom casing 7 has arc-shaped grooves 3 on both sides. The casings 1 are connected by retaining rings 2 for easy installation and disassembly. The bottom casing 7 needs to be installed on the drainage pipe 6, so the bottom of the bottom casing 7 has arc-shaped grooves 3 on both sides to improve the stability of the installation.

[0021] like Figure 5 As shown, a channel steel 4 is erected on each of the top two sides of the pit 6; the middle of the channel steel 4 is fixedly connected to one end of at least one cable 5, and the other end of the cable 5 can hold the retaining ring 2 of the bottom casing 7. When the bottom casing 7 is erected on the drainage pipe 6, the cable 5 provides most of the support force, making the bottom casing 7 less prone to displacement and ensuring personnel safety.

[0022] The support components can be installed inside the foundation pit 6.

[0023] As a preferred option, the middle of the channel steel 4 is also fixedly connected with the same number of cables 5 as the upper protective casing 1. The other ends of these cables 5 can be respectively suspended by the retaining rings 2 of each upper protective casing 1, further ensuring personnel safety.

[0024] Specifically, in this embodiment, the retaining ring 2 is made of HPB300Φ14 steel bar bent into an arch shape, and the bottom two ends of the retaining ring 2 are fixedly connected to the upper inner wall of the upper casing 1; the upper casing 1 is made of 10mm thick steel plate; the cable 5 is made of 20mm diameter steel wire rope.

[0025] Specifically, the arch of the retaining ring 2 protrudes 15cm from the upper protective sleeve, and the protruding part of the retaining ring 2 is inclined inward at an angle of 15°; the distance between two adjacent retaining rings 2 is 500mm.

[0026] The upper casing 1 has a height of 1.5m, an ellipticity of less than d / 100, a maximum allowable deviation of the casing surface inclination of less than 3mm, and a longitudinal axis bending sag of no more than 0.1% of the height of the upper casing 1.

[0027] The upper casing 1 has a steel plate thickness of 10mm. The steel plate is cut into 1.5m wide pieces, and the length is based on the diameter of the inspection well. Ensure that there is a 15cm gap between the steel casing and the side wall of the inspection well. The plate is rolled using a rolling machine. Then, the steel plate joints are welded. Double-sided welding is used, and both sides of the joint must be fully welded (the weld must be uniform and full). After welding, two coats of anti-rust paint are applied to each side of the weld.

[0028] A method for operating inspection wells: In this embodiment, an excavator is used to excavate the soil within 300mm below the ground level of the manhole, and the excavated pit sidewalls are manually trimmed. Then, a rotary drilling rig with a drill bit diameter of 1.8m-2.3m is used to excavate the manhole pit. After excavation, a truck-mounted crane is used to hoist the steel casing section by section into the pit. Each section of the steel casing is connected with a snap ring. Then, two 20# channel steels are symmetrically placed at the top of the pit, and two 20mm diameter steel wire ropes are used to suspend the bottom steel casing onto the top channel steel to complete the steel casing support and begin manhole construction. After the manhole construction is completed, the truck-mounted crane is used to hoist the steel casing section by section out, and then medium-coarse sand is used to backfill and compact the gap between the manhole and the pit sidewalls.

[0029] Specifically, it includes the following steps: Step 0: Prepare a special construction plan for the steel casing support of the inspection well based on the actual site conditions and geological conditions. Drill a directional borehole and lower the drainage pipe 8 into it; delineate a circular area on the ground corresponding to the location of the drainage pipe 8 as the work area, and determine the foundation bottom elevation of the inspection well according to actual needs; As a further supplement, in this embodiment, the location and layout of the manhole foundation pit are carried out according to the drawings, and the distribution of underground pipelines at the location of the manhole is detected. If the underground pipelines have an impact, the location of the manhole can be adjusted appropriately to avoid the underground pipelines.

[0030] Cut according to the positioning and layout of the inspection well, and the cutting depth shall not be less than 100mm. After the cutting is completed, the concrete pavement shall be broken up, and the concrete blocks shall be removed in time.

[0031] The manhole foundation pit is excavated using an excavator or rotary drilling rig. Before excavation, the surrounding environment must be carefully checked to avoid unsafe factors such as overhead power lines and cables, and to ensure that there are no utility poles, trees, or other obstructions to construction. At the same time, the entire construction road must be surveyed to ensure that the excavator and rotary drilling rig can smoothly enter the construction site and that the construction conditions are met.

[0032] For foundation pits with a depth of less than 4.5m, an excavator should be used for excavation. During excavation, foundation pits with a depth of less than 3m can be excavated into square pits. The excavation dimensions of the manhole foundation pit must ensure that there is a gap between each side and the outer wall of the manhole. At the same time, the excavation depth should be controlled to avoid over-excavation.

[0033] For foundation pits deeper than 4.5m, rotary drilling rigs are used for excavation. Before excavation, the drill bit must be pre-processed to ensure the borehole diameter meets requirements. During drilling, the verticality of the drill rod must be continuously measured to ensure the hole is vertically downward. After drilling is completed, the borehole diameter is measured using measuring instruments to ensure consistency across the entire hole.

[0034] Step 1: Make the inner diameter of the pit 6 larger than the diameter of the defined circular area, and use an excavation device to carry out the first excavation. The bottom of the pit 6 is located above the drainage pipe 8. Step 2: The foundation pit 6 is excavated a second time by manual labor until the upper part of the drainage pipe 8 is exposed; Step 3: Use an external hoisting device to lift the retaining ring 2 of the bottom casing 7 and lower the bottom casing 7 into the pit 6 so that the retaining groove 3 at the bottom of the bottom casing 7 is engaged with the upper part of the drainage pipe 8. Specifically, the external hoisting device uses a truck-mounted crane. When hoisting, a traction rope must be attached to the shackle 2 to prevent the steel casing from swinging during hoisting.

[0035] Step 4: Level the bottom casing 7 to ensure that the verticality deviation is no more than 1%. Set up two channel steels 4 on the top of the pit 6, and then use the corresponding cables 5 to suspend the retaining rings 5 ​​on both sides of the bottom casing 7. Step 5: Use external hoisting equipment to continue lowering the upper casing 1 until the support assembly is formed. Use cables 5 to suspend the corresponding retaining rings 5 ​​of each upper casing 1. Step 6: The foundation pit 6 is excavated for the third time by manual labor, excavating to the bottom elevation of the foundation; the circumferential area of ​​the excavation is reduced inward, and the diameter of the reduced circumferential area is not less than the diameter of the inspection well. In this step, the purpose of reducing the circumferential area of ​​the excavation is to have soil support at the bottom of the bottom casing 7, which further improves safety.

[0036] Step 7: Construct the inspection well coaxially within the support assembly until the inspection well is completed. During construction, ensure a 15cm gap between the outer wall of the inspection well and the casing to facilitate plastering. Simultaneously, keep the inner wall of the casing as clean as possible during construction to extend its service life.

[0037] Step 8: Using external hoisting equipment, lift the upper casing 1 and the lower casing 7 section by section from top to bottom. When lifting the casings, ensure stability to avoid collisions with the manhole sidewalls and damage to the manhole. Complete the manhole foundation pit support; then backfill the annular zone between the outer wall of the manhole and the foundation pit 6, and seal the manhole opening with a manhole cover to complete the overall operation.

[0038] After the casing is completely removed from pit 6, medium-coarse sand is used to backfill the gap between pit 6 and the manhole. The backfill sand is compacted using a water-pump method, filling to a depth of 2.5m below the top of pit 6. Subsequently, 3:7 lime-soil is used to backfill the gap within a 2.5m height range below the top of pit 6, and manual compaction is used to ensure that the backfill soil density meets the design requirements. When backfilling the top 2.5m range with 3:7 lime-soil, it must be done simultaneously with the manhole construction and backfilling.

[0039] Specifically, in step 1, during the initial excavation, the bottom of the foundation pit 6 is positioned 150mm above the drainage pipe 8; In step 2, during the second excavation, the upper part of the drainage pipe 8 is exposed by more than 150mm.

[0040] Specifically, in step 6, the excavated circumferential area is reduced inward by 50mm.

[0041] Specifically, in step 7, when constructing the inspection well coaxially within the support assembly, the distance between the outer wall of the inspection well and the inner wall of the support assembly shall not be less than 15cm.

[0042] Specifically, before the manhole is completed, the external hoisting device always holds the retaining ring 2 of the bottom upper casing 1.

Claims

1. A foundation pit support device for a confined space inspection well, characterized in that, Includes a support assembly installed inside the foundation pit (6); the support assembly includes multiple upper casings (1) connected vertically end to end and a bottom casing (7). The upper inner wall of the upper protective sleeve (1) is uniformly fixed with multiple retaining rings (2) along the circumference. The upper part of the retaining ring (2) protrudes from the upper end of the upper protective sleeve (1), and the protruding part of the retaining ring (2) is inclined inward. The structure of the bottom casing (7) is the same as that of the upper casing (1), and the bottom of the bottom casing (7) has arc-shaped slots (3) on both sides. A channel steel (4) is erected on each of the opposite sides of the top of the foundation pit (6); the middle of the channel steel (4) is fixedly connected to one end of at least one cable (5), and the other end of the cable (5) can hold the retaining ring (2) of the bottom casing (7).

2. The manhole foundation pit support device as described in claim 1, characterized in that, The channel steel (4) is also fixedly connected with cables (5) of the same number as the upper casing (1). The other ends of these cables (5) can be hung on the retaining rings (2) of each upper casing (1) in a corresponding manner.

3. The manhole foundation pit support device as described in claim 2, characterized in that, The retaining ring (2) is made of HPB300Φ14 steel bars bent into an arch shape, and the bottom two ends of the retaining ring (2) are fixedly connected to the upper inner wall of the upper casing (1); The upper casing (1) is made of 10mm thick steel plate.

4. The manhole foundation pit support device as described in claim 3, characterized in that, The arch of the retaining ring (2) protrudes 15cm from the upper protective sleeve (1), and the protruding part of the retaining ring (2) is inclined inward at an angle of 15°. The distance between two adjacent retaining rings (2) is 500mm.

5. The manhole foundation pit support device as described in claim 4, characterized in that, The upper casing (1) has a height of 1.5m, an ellipticity of less than d / 100, a maximum allowable deviation of the inclination of the casing surface of less than 3mm, and a longitudinal axis bending sag of no more than 0.1% of the height of the upper casing (1).

6. A method for operating a manhole, the method being based on the manhole foundation pit support device as described in claim 5, characterized in that, Includes the following steps: Step 0: Drill a directional borehole and lower the drainage pipe (8) into the directional borehole; delineate a circular area on the ground corresponding to the location of the drainage pipe (8) as the work area, and determine the foundation bottom elevation of the inspection well according to actual needs; Step 1: Make the inner diameter of the pit (6) larger than the diameter of the defined circular area, and use an excavation device to carry out the first excavation. The bottom of the pit (6) is located above the drainage pipe (8). Step 2: The foundation pit (6) is excavated a second time by manual labor until the upper part of the drainage pipe (8) is exposed; Step 3: Use an external hoisting device to hoist the retaining ring (2) of the bottom casing (7) and lower the bottom casing (7) into the pit (6) so that the retaining groove (3) at the bottom of the bottom casing (7) is engaged with the upper part of the drainage pipe (8); Step 4: Level the bottom casing (7) to ensure that the verticality deviation is no more than 1%. Set up two channel steels (4) on the top of the pit (6), and then use the corresponding cables (5) to hang the retaining rings (5) on both sides of the bottom casing (7). Step 5: Use external hoisting equipment to continue lowering the upper casing (1) until the support assembly is formed. Use cables (5) to hoist the shackles (5) of each upper casing (1) one by one. Step 6: The foundation pit (6) is excavated for the third time manually, down to the foundation bottom elevation; the excavation area during the third excavation is reduced inward, and the diameter of the reduced excavation area is not less than the diameter of the inspection well. Step 7: Construct inspection wells coaxially within the support components until the inspection wells are completed; Step 8: Use external hoisting equipment to hoist the upper casing (1) and the lower casing (7) from top to bottom section by section to complete the support of the inspection well foundation pit; Backfill the annular zone between the outer wall of the manhole and the foundation pit (6), and seal the manhole opening with a manhole cover to complete the overall operation.

7. The method for operating inspection wells as described in claim 6, characterized in that, In step 1, during the initial excavation, the bottom of the foundation pit (6) is positioned 150mm above the drainage pipe (8); In step 2, during the second excavation, the upper part of the drainage pipe (8) is exposed by more than 150mm.

8. The method for operating inspection wells as described in claim 7, characterized in that, In step 6, the excavated circumferential area is reduced inward by 50mm.

9. The method for operating inspection wells as described in claim 8, characterized in that, In step 7, when constructing the inspection well coaxially within the support assembly, the distance between the outer wall of the inspection well and the inner wall of the support assembly shall not be less than 15cm.

10. The method for operating a manhole as described in claim 6, characterized in that, Before the manhole is completed, the external hoisting device always holds the retaining ring (2) of the bottom upper casing (1).

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