A method for constructing a self-flowing pipe

Abstract

The present invention belongs to the technical field of water intake engineering, and provides a method for constructing a gravity pipe, including: step S1, constructing a welding processing site for gravity pipes at a riverside wharf; step S2, welding gravity pipes; step S3, floating pipe sections; step S4, excavating a foundation pit for gravity pipes; step S5, hoisting pipe sections; step S6, installing the lower half of the half section; step S7, sinking the pipe section; step S8, installing the upper half of the half section; step S9, for other pipe sections, repeating steps S5 to S8 until the connection of multiple pipe sections constituting the gravity pipe is completed; step S10, checking the sealing of the half section; step S11, backfilling the gravity pipe. In the gravity pipe construction method involved in the present application, the pipe sections are connected by half sections, which has better sealing performance and saves construction costs.

Description

Technical Field

[0001] The invention belongs to the technical field of water intake engineering, and in particular relates to a gravity pipe construction method. Background Art

[0002] A gravity pipe, also known as a gravity inlet pipe, refers to a pipe that flows water from the water intake head located in the riverbed into the gravity pipe in the form of gravity flow.

[0003] A gravity pipe is usually formed by welding multiple pipe sections underwater. Underwater welding is difficult and has high welding costs. Therefore, the present application provides an improved gravity pipe construction method to address the deficiencies in the prior art. Summary of the invention

[0004] In order to achieve the above object, the present invention provides the following technical solutions:

[0005] A method for constructing a gravity pipe, the improvement of which is that the gravity pipe connects a water intake pump station and a water intake head; the method for constructing a gravity pipe comprises:

[0006] Step S1, constructing a welding processing site for gravity pipes at a riverside wharf; the welding processing site is leveled by excavating equipment, and a crushed stone cushion layer is manually laid; the welding processing site includes a prefabricated pipe stacking area and a pipe joint welding area of ​​the gravity pipe; a crane sequentially lifts the prefabricated pipes in the prefabricated pipe stacking area to the pipe joint welding area; the pipe joint welding area and the prefabricated pipe stacking area are arranged oppositely, and the crane is arranged between the pipe joint welding area and the prefabricated pipe stacking area; a line connecting the center points of the pipe joint welding area, the prefabricated pipe stacking area and the crane forms a triangle;

[0007] Step S2, welding of a gravity pipe; the gravity pipe comprises two pipes; each pipe comprises pipe sections connected in sequence; the pipe sections comprise a plurality of pipe sections of different lengths, including: 6 pipe sections of a first length, 1 pipe section of a second length, and 1 pipe section of a third length; each pipe section of different lengths is welded by a plurality of prefabricated pipes; Step S2 comprises:

[0008] Step S2-1, welding the butted prefabricated pipes;

[0009] Step S2-2, using sealing steel plates at both ends of each pipe segment to seal the two pipe openings of the pipe segment;

[0010] Step S2-3, air pressure tightness test of the pipe joint; the test pressure is 0.2MPa, and the pressure value is maintained unchanged for 30 minutes to meet the air pressure tightness requirement; if the pipe joint meets the test requirements, proceed to the next step S4; if the pipe joint does not meet the test requirements, proceed to step S2-4;

[0011] Step S2-4, repairing the pipe joint;

[0012] Step S3, floating the pipe segments; using a tugboat to tow the pipe segments to a preset sinking area in sequence;

[0013] Step S4, excavation of the gravity pipe foundation pit; the gravity pipe foundation pit excavation adopts layered positioning step-type excavation;

[0014] Step S5, pipe segment hoisting: the first floating crane and the second floating crane are used to hoist the pipe segment at the same time;

[0015] Step S6, installing the lower half of the half section; the half section includes a lower half and an upper half that are coaxially connected; the lower half and the upper half are matched and connected, and are arranged at the connection of each pipe section to connect the two butted pipe sections;

[0016] Step S7, the pipe section sinks;

[0017] Step S8, installing the upper half of the half section;

[0018] Step S9, repeating steps S5 to S8 for other pipe sections until the connection of multiple pipe sections constituting the gravity flow pipe is completed;

[0019] Step S10, checking the sealing performance of the half joint, including: checking the gap size between the half joint and the pipe joint and the density of the sealing material;

[0020] Step S11, backfilling the flow pipe.

[0021] Preferably, step S2-1 includes: step S2-1-1, sequentially setting a first position, a second position and a third position from the shore toward the lake surface; and setting a prefabricated pipe at each of the first position, the second position and the third position;

[0022] Step S2-1-2, welding the prefabricated pipes arranged at the first position, the second position and the third position into one body, and setting the prefabricated pipes welded into one body as welded prefabricated pipes;

[0023] Step S2-1-3, hoisting the welded prefabricated pipe to the lake surface, and reserving the first position, the second position and the third position for placing subsequent prefabricated pipes and welding them;

[0024] Step S2-1-4, placing the subsequent three prefabricated pipes at the first position, the second position and the third position respectively; continuing to weld the end of the welded prefabricated pipe away from the lake surface with the prefabricated pipe at the third position;

[0025] Step S2-1-5, repeat steps S2-1-2 to S2-1-4, and continue welding other prefabricated pipes until the pipe section of the preset length is completed.

[0026] Preferably, the welding in step S2-1 includes: welding the butted prefabricated pipes by using carbon dioxide gas shielded welding; performing 100% flaw detection on the welding interfaces of the prefabricated pipes; and providing no less than 6 reinforcing steel plates at each welding interface.

[0027] Preferably, step S4, excavation of the gravity pipe foundation pit includes: step S4-1, using air suction and discharge method to excavate the silt on the upper part of the lake bed to excavate the upper part of the gravity pipe foundation pit; step S4-2, using impact crushing method to excavate the rock on the lower part of the lake bed to excavate the lower part of the gravity pipe foundation pit; the gravity pipe foundation pit is divided into 4 layers from top to bottom, and the height of each layer is 1m; the slope ratio of the gravity pipe foundation pit is a reverse slope of 1:2.5; step S4-3, underwater leveling of the gravity pipe foundation.

[0028] Preferably, step S5, hoisting, includes: step S5-1, selecting a hoisting point; step S5-2, performing hoisting stress and deformation verification; step S5-3, welding a lifting lug.

[0029] Preferably, step S6, installing the lower half of the half, includes:

[0030] Step S6-1, placing the lower half of the half on the transport ship,

[0031] Step S6-2, when the pipe section lifted by the first floating crane and the second floating crane stays at a height of about 1m on the lake surface, the third floating crane is used to lift the lower half of the half to the pipe section and connect it to the lifted pipe section; at the same time, a buoy is set on the top of the end face of the lifted pipe section to locate the joint position;

[0032] Step S6-3, the transport ship leaves the lifting area, and the third floating crane is separated from the lifting.

[0033] Step S7, sinking of the pipe segment, includes sinking the pipe segment using a straight line floating pipe sinking method: sinking the first end of the pipe segment, when the axis of the pipe segment is a straight line, by adjusting the lifting force of the first floating crane and the second floating crane and the amount of water injected into the pipe segment, the first end of the pipe segment is sunk to the bottom of the gravity pipe foundation pit, and then continuing to inject water to gradually sink the entire pipe segment into the gravity pipe trench; each pipe segment is connected head to tail in sequence.

[0034] Preferably, step S8, installing the upper half of the half section, includes:

[0035] Step S8-1, docking the upper half of the Haff and the lower half of the Haff: when the upper half of the Haff is lifted to the top of the pipe section by the third floating crane, the diver goes into the water to conduct underwater survey of the positions of the upper half of the Haff and the lower half of the Haff, and tightens the upper half of the Haff and the lower half of the Haff with an extended screw until the upper half of the Haff and the lower half of the Haff are completely docked;

[0036] Step S8-2, remove the upper half of the Hough spreader:

[0037] Step S10, checking the sealing of the half joint, including: checking the size of the gap between the half joint and the pipe joint and the density of the sealing material.

[0038] Preferably, step S10, checking the sealing of the half joint, includes: a diver tries to insert a steel ruler into the half joint; if the steel ruler cannot be inserted into the half joint, it means that the rubber ring is in close contact with the outer wall of the pipe joint; if there is still a gap after the steel ruler is inserted into the half joint, it means that there is a gap between the half joint and the pipe joint or the rubber ring is not in contact with the pipe joint.

[0039] Preferably, step S11, backfilling the flow pipe, includes:

[0040] Step S11-1, using bagged gravel to protect both sides of the gravity pipe;

[0041] Step S11-2, backfilling with sand and gravel;

[0042] Step S11-3, backfilling with rocks, backfilling with rocks 500 mm above the top of the gravity pipe.

[0043] Beneficial effects:

[0044] The present application relates to a method for constructing a gravity pipe that matches a half joint connection. The pipe joints are connected using half joints, which have better sealing performance and save construction costs. The connection and installation of the upper half of the half joint and the lower half of the half joint not only reduces the underwater installation time of the half joint, but also reliably connects the half joint to the pipe joint, enhancing the strength of the joint. It also facilitates the underwater docking of the two connected pipe joints when the pipe joints are sunk, thereby improving the efficiency of underwater docking of the pipe joints when the pipe joints are sunk. The gravity pipe construction method involved in the present application can shorten the construction period, save construction materials, and save construction costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] The drawings constituting a part of the present application are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. Among them:

[0046] Figure 1 A schematic diagram of the connection of the gravity pipe according to the present invention;

[0047] Figure 2 It is a schematic diagram of a welding processing site for a gravity pipe according to the present invention;

[0048] Figure 3 A schematic diagram of the welding of a self-flowing pipe according to the present invention;

[0049] Figure 4Schematic diagram of welding and launching of a gravity flow pipe according to the present invention;

[0050] Figure 5 A schematic diagram of the pipe segment traction according to the present invention;

[0051] Figure 6 A schematic cross-sectional view of a gravity pipe foundation pit according to the present invention;

[0052] Figure 7 A schematic diagram of the pipe segment hoisting points involved in the present invention;

[0053] Figure 8 A front view of the pipe segment lifting lug according to the present invention;

[0054] Fig. 9 A top view of the pipe segment lifting lug according to the present invention;

[0055] Fig.10 A side view of the pipe segment lifting lug according to the present invention;

[0056] Fig.11 One of the half joint connection diagrams involved in the present invention;

[0057] Fig.12 The second schematic diagram of the connection of the half joint involved in the present invention;

[0058] Fig.13 A schematic plan view of the protective tube involved in the present invention;

[0059] Fig.14 A schematic cross-sectional view of the protective tube involved in the present invention;

[0060] Fig.15 A schematic diagram of foundation pit backfilling when the gravity pipe according to the present invention is connected to the water intake head;

[0061] Fig.16 A schematic cross-sectional diagram of the backfilling of a gravity pipe foundation pit according to the present invention;

[0062] Among them, 1. gravity pipe; 2. water intake head; 3. water intake pump station; 4. prefabricated pipe stacking area; 5. pipe segment welding area; 6. crane; 7. first position; 8. second position; 9. third position; 10. rubber tire; 11. welding operation pit; 12. welded prefabricated pipe 13. lake surface; 14. pipe segment; 15. traction boat; 16. lifting point; 17-1. bottom plate; 17-2. main plate; 17-3. rib plate; 18-1. lower half of half; 18-2. upper half of half; 18-3. rubber ring; 18-4. rubber plate; 18-5 bolt; 19. bagged gravel; 20. block stone top pressure area; 21. sand and gravel backfill area; 22. fill. DETAILED DESCRIPTION

[0063] The technical solutions in the embodiments of the present invention are described clearly and completely below. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention belong to the scope of protection of the present invention.

[0064] In the description of the present invention, the terms "longitudinal", "lateral", "upper", "lower", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings. They are only for the convenience of describing the present invention and do not require that the present invention must be constructed and operated in a specific orientation. Therefore, they should not be understood as limitations on the present invention. The terms "connected" and "connected" used in the present invention should be understood in a broad sense. For example, they can be fixed connections or detachable connections; they can be directly connected or indirectly connected through intermediate components. For ordinary technicians in this field, the specific meanings of the above terms can be understood according to specific circumstances.

[0065] The present invention will be described in detail below with reference to the accompanying drawings and in combination with embodiments. It should be noted that the embodiments and features in the embodiments of the present invention can be combined with each other without conflict.

[0066] like Figure 1 As shown, the present application relates to a gravity pipe construction method, the improvement of which is that the gravity pipe 1 connects the water intake pump station 3 and the water intake head 2; the gravity pipe construction method includes:

[0067] Step S1, constructing a welding processing site for gravity pipes at a riverside wharf; the welding processing site is leveled by excavating equipment, and a crushed stone cushion layer is manually laid; the welding processing site includes a prefabricated pipe stacking area 4 and a pipe segment welding area 5 of the gravity pipe; a crane 6 sequentially lifts the prefabricated pipes in the prefabricated pipe stacking area 4 to the pipe segment welding area 5; the pipe segment welding area 5 and the prefabricated pipe stacking area 4 are arranged opposite to each other, and the crane 5 is arranged between the pipe segment welding area 5 and the prefabricated pipe stacking area 4; a line connecting the center points of the pipe segment welding area 5, the prefabricated pipe stacking area 4 and the crane 6 forms a triangle.

[0068] Specifically, the water intake pump station 3 and the water intake head 2 are respectively located on opposite banks of the river, and the gravity pipe 1 connects the water intake pump station 3 and the water intake head 2 .

[0069] The method for constructing a gravity flow pipe comprises: step S1, Figure 2As shown, a prefabricated pipe stacking area 4 is constructed at the river bank for placing multiple prefabricated pipes that need to be subsequently welded. At the same time, a pipe segment welding area 5 of a gravity pipe is constructed at the river bank for welding multiple prefabricated pipes to form pipe segments of the gravity pipe. A crane 6 is also required to facilitate the sequential lifting of the prefabricated pipes in the prefabricated pipe stacking area 4 to the pipe segment welding area 5 for subsequent prefabricated pipe welding work. In order to facilitate the lifting of prefabricated pipes, the pipe segment welding area 5 and the prefabricated pipe stacking area 4 are arranged relative to each other, and the crane 6 is arranged between the pipe segment welding area 5 and the prefabricated pipe stacking area 4. The triangle formed by connecting the center points of the pipe segment welding area 5, the prefabricated pipe stacking area 4 and the crane 6 is the best construction position.

[0070] When constructing the welding processing site, it is necessary to ensure that the roads and waterways are unobstructed, the power facilities are complete, and the power supply is barrier-free. In addition, an excavator is used to level the site, and a gravel cushion is laid manually. The welding processing site also needs to be enclosed with a fence. In addition, a slope foot with an angle of 5° between the welding site and the lake surface needs to be set.

[0071] Step S2, welding of gravity pipe; gravity pipe includes two pipes; each pipe includes a plurality of pipe sections of different lengths connected in sequence; the plurality of pipe sections of different lengths include: 6 first length pipe sections, 1 second length pipe section and 1 third length pipe section; each pipe section of different length is welded by a plurality of prefabricated pipes. Specifically, the prefabricated pipe model used in this application is: DN1220×12×12000, that is, a prefabricated pipe with a diameter of 1220mm, a thickness of 12mm and a length of 12m. Each pipeline includes: a first length pipe section of 96m, welded with 8 prefabricated pipes; a total of 12 first length pipe sections need to be prepared, that is, each pipeline of the gravity pipe requires 6 first length pipe sections. The second length pipe section is 60m, welded with 5 prefabricated pipes; a total of 2 second length pipe sections need to be prepared, that is, each pipeline of the gravity pipe requires 1 second length pipe section. The third length pipe section is 12m, and two prefabricated pipes can be directly used, that is, each pipeline of the gravity pipe requires one third length pipe section.

[0072] Step S2 includes:

[0073] Step S2-1, welding the butted prefabricated pipes; comprising:

[0074] Step S2-1-1, sequentially setting a first position 7, a second position 8 and a third position 9 from the shore toward the lake surface 13; and setting a prefabricated pipe at each of the first position, the second position and the third position;

[0075] Step S2-1-2, welding the prefabricated pipes arranged at the first position 7, the second position 8 and the third position 9 into one body, and setting the prefabricated pipes welded into one body as welded prefabricated pipes;

[0076] Step S2-1-3, hoisting the welded prefabricated pipe to the lake surface 13, and reserving the first position 7, the second position 8 and the third position 9 for placing subsequent prefabricated pipes and welding them;

[0077] Step S2-1-4, placing the subsequent three prefabricated pipes at the first position 7, the second position 8 and the third position 9 respectively; continuing to weld the end of the welded prefabricated pipe away from the lake surface 13 with the prefabricated pipe at the third position;

[0078] Step S2-1-5, repeat steps S2-1-2 to S2-1-4, and continue welding other prefabricated pipes until the pipe section of the preset length is completed.

[0079] Specifically, Figure 3 As shown, in step S2-1-1, three positions are set in sequence from the shore to the lake surface 13, and a prefabricated pipe is placed at each position. Under each end of each prefabricated pipe, a flat rubber tire 10 is set to prevent the prefabricated pipe from rolling. Figure 4 As shown, a welding operation pit 11 is also required to be set at the connection of the two prefabricated pipes to facilitate welding work. The welding operation pit 11 is a depression on the ground, and the construction method and shape are not limited, as long as it is convenient for the welding of prefabricated pipes;

[0080] Step S2-1-2, welding the prefabricated pipes arranged at the first position, the second position and the third position into one body, and setting the prefabricated pipes welded into one body as the welded prefabricated pipe 12. Step S2-1-3, as Figure 4 As shown, the welded prefabricated pipe 12 is hoisted to the lake surface 13, and the first position 7, the second position 8 and the third position 9 are reserved for placing subsequent prefabricated pipes and welding. Step S2-1-4, the first end of the welded prefabricated pipe is connected to the lifting device and hoisted to the lake surface, and the second end of the welded prefabricated pipe, that is, the end away from the lake surface 13, needs to continue to be welded with the subsequent prefabricated pipe. Step S2-1-5, repeat steps S2-1-2 to S2-1-4, the welded prefabricated pipe continues to be hoisted by the lifting device, moved to the lake surface, and the reserved first position, second position and third position continue to place subsequent prefabricated pipes and weld, until the production of the pipe section 14 of the preset length is completed;

[0081] Preferably, the welding method of step S2-1 includes: welding the butted prefabricated pipes by using carbon dioxide gas shielded welding; performing 100% flaw detection on the welding interface of the prefabricated pipes; and providing no less than 6 reinforcing steel plates at each welding interface;

[0082] Specifically, the welding between the prefabricated pipes is carried out by carbon dioxide gas shielded welding. The welding quality standard shall comply with the design specifications and design standards. The welding interface shall be inspected by 100% flaw detection. After passing the inspection, each welding port shall be provided with no less than 6 reinforcing steel plates, and the thickness of the reinforcing steel plates shall not be less than 14mm. The prefabricated pipes of this application need to consider reinforcing steel plates at the weld position during welding processing to avoid the overall stiffness being too low during the floating installation process, causing deformation of the steel pipe and avoiding irreparable losses. The reinforcing steel plate adopts ordinary steel plate: 300mm long * 100mm wide * 14mm thick. At the weld position, along the weld direction, 6 reinforcing steel plates are evenly arranged at each weld and welded to the two prefabricated pipes that are butt-jointed. After the pipe section is welded and passed the inspection, proceed to step S2-2.

[0083] Step S2-2, both ends of each pipe section are sealed with a sealing steel plate to seal the two pipe openings of the pipe section. Specifically, after step S2-1-2 and before step S2-1-3, before the welded prefabricated pipe is pulled to the lake surface, a sealing steel plate is set at the first end of the welded prefabricated pipe, that is, at the first end of the pipe section to seal the pipe opening of the first end of the pipe section. In step S2-1-5, when the production of the pipe section of the preset length is completed, a sealing steel plate is set at the second end of the manufactured pipe section to seal the pipe opening of the second end of the pipe section. Among them, the sealing steel plate is a circular steel plate with a thickness of 16 mm, and a circular boss is set on the surface of the steel plate. The diameter of the boss matches the diameter of the pipe section, and it can be stuck into the pipe opening of the pipe section during installation. It is also necessary to set an air inlet valve on the sealing steel plate at the first end of the pipe section, and set an air outlet valve on the sealing steel plate at the second end of the pipe section. Preferably, after plugging, reinforcing ribs may be welded onto the plugging steel plate to increase the sealing performance of the pipe joint and prepare for subsequent sealing tests.

[0084] Step S2-3, air pressure tightness test of pipe joints, test pressure is 0.2MPa, and the pressure value is maintained unchanged for 30 minutes to meet the air pressure tightness requirements; if the pipe joint meets the test requirements, proceed to step S4; if it does not meet the test requirements, proceed to step S2-4. Specifically, step S2-3-1, select the test medium: the test medium is dry and clean air, nitrogen or other non-flammable and non-toxic gases. Step S2-3-2, set the pressure relief device: the pressure relief device is installed during the test, and its set pressure shall not be higher than 1.1 times the test pressure. Step S2-3-3, conduct a preliminary test of air pressure tightness of the pipe joint: before the formal air pressure tightness test of the pipe joint, a preliminary test should be carried out with air, and the test pressure should be 0.1MPa. Step S2-3-4, perform the air pressure sealing test of the pipe joint: during the test, the pressure should be increased slowly. When the pressure rises to 50% of the test pressure, if no abnormality or leakage is found, the pressure should continue to be increased step by step by 10% of the test pressure, and the pressure should be maintained for 3 minutes at each level until the test pressure is reached. Step S2-3-5, check for gas leakage: there should be no leakage when using a foaming agent for inspection, and the pressure stop time should be determined according to the needs of the leak detection work. If the pipe joint meets the test requirements, proceed to step S4; if it does not meet the test requirements, proceed to step S2-4.

[0085] Step S2-4, repair the pipe joint, including repairing the outer anti-corrosion layer and the inner anti-corrosion layer of the pipe joint patch. Specifically, the patch is to repair and seal the welded joint of the butt-jointed prefabricated pipe. Step S2-4 includes: 1) Removing defects such as weld nodules, burrs and corners on the surface of the pipe joint, and removing pollutants such as oil, grease, dust, etc. that affect the surface treatment or the adhesion between the anti-corrosion layer and the pipe joint. 2) The surface treatment method, surface roughness and treatment width of the anti-corrosion layer in the overlap area of ​​the pipe joint patch and the patch material should meet the requirements of the patch material used. 3) When the patch material is epoxy primer, the primer must be prepared and evenly applied in accordance with the requirements of the construction process regulations, and the wet film thickness of the primer should not be less than 150mm. The overlap amount should ensure that the overlap with the anti-corrosion layer of the pipe body is not less than 100mm. 4) The appearance of the patch should be visually inspected one by one, and the surface of the patch anti-corrosion layer should be flat, without wrinkles, bubbles, hollows, burns, carbonization, etc.

[0086] Step S3: Pipe segment floating. The tugboat tows the pipe segment 14 to a preset sinking area. Figure 5 As shown, the traction boat 15 is connected to the first end of the pipe section to pull the pipe section to move to the preset area. Preferably, when the buoyancy of the pipe section during floating transportation is not enough to make it float, the end of the pipe section can be hoisted and connected to the floating crane for floating transportation.

[0087] Step S4, excavation of the gravity pipe foundation pit; the gravity pipe foundation pit excavation adopts layered positioning step-type excavation;

[0088] Step S4-1: Use air suction and discharge to remove the silt on the upper part of the lake bed and excavate the upper part of the gravity pipe foundation pit.

[0089] Specifically, an air suction machine is used for excavation, and an above-water suction mud operation platform is set up. The above-water suction mud operation platform is connected in sequence with the mud suction device, the high-pressure pneumatic device, the mud and sand conveying device, the mud spraying device and other devices commonly used in the prior art for mud suction operations. When the mud suction operation is in progress, the high-pressure pneumatic device forms a high wind speed environment, sucks away the mud, sand and water mixture sucked in by the mud suction device, transports it to the mud spraying device by the mud and sand conveying device, and sprays it out through the mud spraying device. As the mud, sand and water mixture is sprayed out, the mud suction operation platform gradually sinks under the action of its own gravity, and can suck out mud, sand, gravel and most of the pebbles 35 meters below the lake surface. The extracted silt and gravel are transported to the mud pool on the shore by mud barges, and the mud is transported and disposed of at the designated soil dump after airing or dehydration.

[0090] Step S4-2: Use impact crushing to remove the rocks at the bottom of the lake bed and excavate the lower part of the gravity pipe foundation pit.

[0091] Specifically, the rocks in the lake are medium-weathered rocks. The construction method is to replace the bucket of the water dredger with an impact hammer, first crush the rocks, and then use the dredger to excavate. The excavated waste rocks are transported to the shore by transport ships for drying or dehydration treatment, and then transported and disposed of at the designated soil dump of the construction unit.

[0092] The equipment required for the excavation of the gravity pipe foundation pit is: two assembled dredgers and an excavator for foundation pit excavation and earth and stone transportation. The slope excavation and excavation depth of the gravity pipe foundation pit need to be constructed according to the design requirements and controlled by sonar measurement data. Figure 6 As shown, the gravity pipe foundation pit of this application adopts a layered stepped excavation method, which is divided into 4 layers from top to bottom, with a height of 1m for each layer. The first and second layers belong to the upper silt area of ​​the lake bed, and the third and fourth layers belong to the lower rock area of ​​the lake bed. The width of the foundation pit gradually narrows from top to bottom, forming a reverse slope with a slope ratio of 1:2.5.

[0093] Step S4-3, after the excavation of the foundation pit of the gravity pipe, the bottom of the foundation pit should be leveled underwater. Underwater leveling mainly adopts high-pressure water gun jet to trim the uneven bottom of the foundation pit, so as to ensure that the requirements of the acceptance of the foundation pit of the gravity pipe and the installation of each pipe section of the gravity pipe are met. After the foundation pit is excavated to the design elevation and is corrected by rope measurement or sonar measurement, gravel is paved and underwater leveling is performed by divers. After the rope measurement or sonar re-measurement is qualified, the subsequent pipe section sinking work can be carried out.

[0094] Step S5, pipe segment hoisting, using a first floating crane and a second floating crane to hoist the pipe segment; the first floating crane is hoisted and connected to the front of the pipe segment; the second floating crane is hoisted and connected to the rear of the pipe segment.

[0095] Step S5-1, select the suspension point 16. Specifically, Figure 7 As shown, the first floating crane is provided with two lifting points 16 at corresponding positions of 1 / 8 and 3 / 8 of the length of the pipe segment, that is, two lifting points are provided at the front of the pipe segment to be hoisted and connected with the pipe segment. The second floating crane is provided with two lifting points 16 at corresponding positions of 5 / 8 and 7 / 8 of the length of the pipe segment, that is, another two lifting points are provided at the rear of the pipe segment to be hoisted and connected with the pipe segment.

[0096] Step S5-2, perform hoisting stress and deformation verification; specifically, based on the related verification of pipe joint hoisting in the prior art, it is used to prevent the pipe joint from having axial distortion, circumferential deformation, longitudinal bending, etc. that exceed the allowable range, and avoid external force damage.

[0097] Step S5-3, welding the lifting lugs, welding the lifting lugs on the lifting points 16. The lifting lugs include a bottom plate 17-1, a main plate 17-2 arranged on the bottom plate, the main plate having lifting holes; and ribs 17-3 arranged on both sides of the main plate. Figures 8 to 10 As shown, the lifting lug includes a bottom plate 17-1, which is a plate-shaped object, has a curvature that matches the surface of the pipe segment 14, and can be welded on the surface of the pipe segment. The main plate 17-2 is a plate-shaped object, and a lifting hole is set in the center. The shape of the main plate is not limited, and the main plate is set coplanar with the axis of the pipe segment; ribs are also set on both sides of the main plate. The rib 17-3 is a plate-shaped object, and the bottom surface of the rib 17-3 is set with a curvature corresponding to the bottom plate 17-1. The rib 17-3 is perpendicular to the bottom plate 17-1 and also perpendicular to the main plate 17-2. At the same time, it is connected to the bottom plate 17-1 and the main plate 17-2. A rib 17-3 is set on the left and right sides of the lifting hole; the ribs 17-3 are set on both sides of the main plate 17-3.

[0098] Step S6, installing the lower half of the half section 18-1; the half section includes the lower half of the half section 18-1 and the upper half of the half section 18-2 which are coaxially connected; the lower half of the half section 18-1 and the upper half of the half section 18-2 are matched and connected, and are arranged at the connection of each pipe section 14 to connect the butted pipe sections 14. Specifically, as Fig.11 and Fig.12As shown, the rubber ring 18-3 is used as a sealing material and is arranged at both ends of the pipe section and needs to extend out of the end face of the pipe section. A rubber plate 18-4 is arranged at the interface of the two butted pipe sections. The rubber plate 18-4 is coplanar with the axial section of the pipe section 14 to form the wing plate of the half section, which is used to connect the lower half section 18-1 and the upper half section 18-2. The half section can be understood as two upper and lower semicircular sleeves connecting the butted pipe sections. The butt joint of the two butted pipe sections is the center position of the half section. Therefore, in the subsequent step of installing the lower half section, the lower half section 18-1 is coaxially connected to one end of the pipe section 14. The center position of the lower half section 18-1 is coplanar with the end face of the pipe section 14, and a position for connecting with the next pipe section is reserved. In order to enhance the sealing performance of the half section, a rubber plate 18-4 is also arranged at the butt joint of the lower half section 18-1 and the upper half section 18-2 to ensure the sealing effect of the half section. The lower half piece and the upper half piece are connected by a plurality of parallelly arranged bolts 18-5.

[0099] Step S6-1, placing the lower half of the Haff 18-1 on the transport ship.

[0100] Step S6-2, when the pipe segment lifted by the first floating crane and the second floating crane stays at a height of about 1m on the lake surface, the third floating crane is used to lift the lower half of the half 18-1 to the pipe segment 14 and connect it to the lifted pipe segment 14; at the same time, a buoy is set on the top of the end face of the lifted pipe segment to locate the joint position;

[0101] Step S6-3, the transport ship leaves the lifting area, and the third floating crane is separated from the lifting.

[0102] Specifically, step S6-1, before lifting the pipe segment, place the lower half of the half 18-1 on the fixed bracket of the small transport ship. Step S6-2, when the first floating crane and the second floating crane lift the pipe segment 14 and stay at a height of about 1m on the lake surface, use the third floating crane to lift the lower half of the half 18-1 from the small transport ship, connect the lower half of the half 18-1 to the pipe segment 14, and the center position of the lower half of the half 18-1 is coplanar with the end face of the pipe segment 14; bolt the lower half of the half 18-1 to the wing plate, and set a buoy on the top of the end face of the pipe segment to locate the joint position of the pipe segment. The pipe segment of the present application is connected from the water intake pump station to the water intake head. The water intake pump station pipeline with the lower half of the half installed is pre-set at the water intake pump station, so there is no need to set the lower half of the half separately at the end of the pipe segment connected to the water intake pump station. It is only necessary to set the lower half of the half at the other end of the pipe segment and connect it to the next pipe segment. That is, each pipe section only needs to be provided with a lower half piece of half at the end connected to the next pipe section.

[0103] Step S6-3, the small transport ship then leaves the lifting area, and the third floating crane also leaves the lifting. This not only reduces the underwater installation time of the half joint, but also reliably connects the half joint with the pipe joint 14, enhances the joint strength, and also facilitates the underwater pipe head docking of the two connected pipe joints when the pipe joint is sunk, thereby improving the underwater docking efficiency of the pipe joint when the pipe joint is sunk.

[0104] Step S7, sinking of the pipe section; including, sinking the pipe section by a straight line floating pipe sinking method: sinking the first end of the pipe section, when the axis of the pipe section is a straight line, by adjusting the lifting force of the first floating crane and the second floating crane and the amount of water injected into the pipe section, the first end of the pipe section is sunk to the bottom of the gravity pipe foundation pit, and then continuing to inject water, gradually sinking the entire pipe section into the gravity pipe foundation pit. Specifically, the present application uses the first floating crane and the second floating crane to connect with the four lifting ears set on the pipe section respectively to carry out the lifting operation. The first end of the first pipe section is connected to the water intake pump station pipeline where the lower half of the half has been installed. The specific steps of sinking the pipe section are as follows: start the main crane of the first floating crane or the second floating crane to slowly put the pipe section 14 into the water, strictly control the lifting and unloading of the floating crane to ≤10%, and control the lifting and unloading and water injection into the pipe to slowly and steadily put the pipeline into the water, so as to avoid the pipe section floating up and down and uneven force on the lifting point due to the rapid entry of one end of the pipe section into the water, which will cause the water flow to move back and forth in the pipe cavity, thereby causing a safety hazard in the lifting. The pipe section 14 stops sinking when it enters the water to the middle of the pipe section. After the pipe section is stable, professional surveyors go to the top of the pipe on a transportation boat to locate the pipeline axis.

[0105] Step S8, installing the upper half of the Huff 18-2 of the Huff section; including: Step S8-1, docking the upper half of the Huff 18-2 and the lower half of the Huff 18-1: when the third floating crane lifts the upper half of the Huff 18-1 to the top of the pipe section 14, the diver goes into the water to conduct underwater surveys of the positions of the upper and lower Huffs, and tightens the upper half of the Huff 18-2 and the lower half of the Huff 18-1 with an extended screw until the upper half of the Huff 18-2 and the lower half of the Huff 18-1 are completely docked. Specifically, in this application, the upper half of the Huff 18-2 and the lower half of the Huff 18-1 are installed separately. In order to facilitate the connection of the bolts 18-5 after the upper half of the Huff is sunk and docked, the bolt holes on the wing plate of the lower half of the Huff are horizontal square holes, and the bolt holes on the wing plate of the upper half of the Huff are longitudinal square holes, which can improve the efficiency of underwater bolt insertion and connection. When tightening the bolts used for half joint connections underwater, a special pneumatic torque wrench must be used to improve the bolt tightening efficiency and tightening strength.

[0106] Step S8-2, remove the lifting equipment of the upper half. Specifically, after the half section is connected and underwater safety is ensured, the main hook of the third floating crane is removed and the hook is removed, and finally the lifting work of the single pipe section is completed.

[0107] Step S9, for other pipe sections, repeat steps S5 to S8 until the connection of multiple pipe sections constituting the gravity pipe is completed. Specifically, multiple pipe sections 14 of the gravity pipe are connected to the water intake head from the direction of the water intake pump station. The connection method between the pipe section and the water intake head in this application also adopts the half joint connection. The water intake head reserves a reserved pipeline for connection with the pipe section, and the lower half of the half is set on the pipe section and at the end connected to the water intake head. The connection method between the pipe section and the reserved pipeline of the water intake head is the same as the half joint connection mentioned above. After all the pipe section connection work is completed, a gravity pipe 1 is formed. The present application involves two gravity pipes. After one gravity pipe is connected, the other one is connected.

[0108] Step S10, check the sealing of the half joint, including: check the size of the gap between the half joint and the pipe joint 14 and the density of the sealing material. Specifically, when the bottom of the gravity pipe foundation pit is leveled underwater in step S4-3, a position of about 3m long × 7.15m wide × 0.3m deep is reserved at the center point of the pipe joint as a half joint operation pit, which is convenient for the sealing inspection of the half joint and the wrapping of the anti-seepage geotextile. The sealing inspection of the half joint is specifically: divers perform underwater sealing inspection of the half joint. The main inspection content includes underwater photography with lights to check the size of the gap between the half joint and the pipe joint and the density of the sealing material, and use a 1m long steel ruler to try to insert into the half joint to check whether the rubber ring is in close contact with the outer wall of the pipe joint. If the steel ruler cannot be inserted into the half joint, it means that the rubber ring is in close contact with the outer wall of the pipe joint. If there is still a gap after the steel ruler is inserted into the half joint, it means that the sealing performance of the half joint is not enough. If the inspection finds that the gap between the half joint and the pipe joint is large or the rubber ring is not in close contact with the pipe joint, the diver will use molded steel cement to fill the gap underwater. After all the half joints are inspected, the anti-seepage geotextile specially used for the half joint will be wrapped around it for 2 circles, and the subsequent gravity pipe backfilling work will be carried out after it is tied and fixed.

[0109] Step S11, backfilling the flow pipe, includes:

[0110] Step S11-1, using bagged gravel 19 to protect both sides of the gravity pipe. Figure 13 to Figure 14 As shown, after the gravity pipe is positioned and placed correctly, bagged gravel 19 is used to protect both sides of the gravity pipe every 30 meters. The height of the protection pipe is 60% of the pipe diameter, and the length of the protection pipe matches the width of the gravity pipe foundation pit. In this application, the width of the protection pipe is 2 meters.

[0111] Step S11-2, backfilling with sand and gravel. Specifically, after the water intake pipe and half are installed in place, the dredger enters the site and anchors beside the gravity pipe. The dredger is positioned by GPS so that it is just above the water intake pipe. The pebbles are transported to the dredger by a transport boat for stone backfilling. The pebbles are grabbed by the grab bucket on the dredger and placed in the gravity pipe foundation pit. After the pipes are compacted, divers will measure the underwater backfilling situation, adjust the backfilling position and volume, and backfill the gravity pipe foundation pit to a depth of 0.8m below the original riverbed elevation. Among them, when throwing stones to backfill the sand and gravel on both sides of the pipeline, the two sides need to be backfilled in layers symmetrically, and the thickness of the layered backfill should not exceed 300mm. Before backfilling, mark the excavator arm according to the water depth on the top of the pipe in order to control the depth of the bucket entering the water during backfilling, so that the stones can fall freely in the water and reduce the impact on the pipeline. It is strictly forbidden to throw stones from high altitude on the water, backfill one side of the pipeline or backfill too much at one time.

[0112] Step S11-3, backfill with stone top. Specifically, backfill with stone top is carried out 500mm above the top of the gravity pipe. The stone can be thrown into the area outside the top of the gravity pipe first, and then slowly flattened by the excavator until the backfill thickness and flatness are reached. The strength of the stone used for backfill with stone top is MU30, and the particle size is 200 to 400mm. The riprap material is solid and fresh, without weathering peeling layer or cracks, and there is no dirt, slag and other impurities on the surface of the stone. The stone used for the surface has uniform color. The physical and mechanical indicators of the stone meet the requirements of the construction drawings. When throwing and filling, it is necessary to ensure that the filling is in the designated position, and the measurement is carried out as the throwing is carried out. The flatness and thickness of the riprap need to be measured in time. After the measurement meets the design standard, it can be moved to the new throwing area to ensure the design requirements of the riprap project.

[0113] The final formation is Fig.14 and Fig.15 The self-flowing pipe foundation pit forms a 500mm high rock capping area 20 from top to bottom, and a gravel backfill area 21 below the rock capping area. The self-flowing pipe foundation pit forms a reverse slope with a slope ratio of 1:2.5. The remaining area is filled with backfill soil 22 at the junction of the 1:1 slope at the edge of the rock capping area and the 1:2.5 reverse slope.

[0114] The above are only preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention are within the scope of protection of the pending claims of the present invention.

Claims

1. A method for constructing a gravity pipe, characterized in that: The gravity pipe connects the water intake pump station and the water intake head; the gravity pipe construction method includes: Step S1, constructing a welding processing site for the gravity pipe at the riverside wharf; the welding processing site is leveled by excavating equipment, and a crushed stone cushion layer is manually laid; the welding processing site includes a prefabricated pipe stacking area and a pipe joint welding area of ​​the gravity pipe; the prefabricated pipes in the prefabricated pipe stacking area are sequentially hoisted to the pipe joint welding area by a crane; the pipe joint welding area and the prefabricated pipe stacking area are arranged opposite to each other, and the crane is arranged between the pipe joint welding area and the prefabricated pipe stacking area; the line connecting the center points of the pipe joint welding area, the prefabricated pipe stacking area and the crane is a triangle; the welding site is set with a slope foot of 5° between the welding site and the lake surface; Step S2, welding of a gravity pipe; the gravity pipe comprises two pipes; each of the pipes comprises pipe sections connected in sequence; the pipe sections comprise a plurality of pipe sections of different lengths, including: 6 pipe sections of the first length, 1 pipe section of the second length and 1 pipe section of the third length; each of the pipe sections of different lengths is welded by a plurality of prefabricated pipes; the prefabricated pipe has a diameter of 1220 mm, a thickness of 12 mm and a length of 12 m; the first length pipe section is 96 m; the second length pipe section is 60 m; the third length pipe section is 12 m; Step S2 includes: Step S2-1, welding the butted prefabricated pipes; Step S2-2, using sealing steel plates at both ends of each pipe segment to seal the two pipe openings of the pipe segment; Step S2-3, air pressure tightness test of the pipe joint; the test pressure is 0.2MPa, and the pressure value is maintained unchanged for 30 minutes to meet the air pressure tightness requirement; if the pipe joint meets the test requirements, proceed to the next step S4; if the pipe joint does not meet the test requirements, proceed to step S2-4; Step S2-4, repairing the pipe joints that do not meet the test requirements; Step S3, floating the pipe segments; using a tugboat to tow the pipe segments to a preset sinking area in sequence; Step S4, excavating a foundation pit for a gravity pipe; the excavation of the foundation pit for a gravity pipe adopts a layered positioning step-type excavation; Step S5, pipe segment hoisting: the first floating crane and the second floating crane are used to hoist the pipe segment at the same time; Step S6, installing the lower half of the half section; the half section comprises a coaxially connected lower half and an upper half; the lower half and the upper half are matched and connected, and are arranged at the connection of each pipe section to connect the two butted pipe sections; Step S7, the pipe section sinks; Step S8, installing the upper half of the half section; Step S9, repeating steps S5 to S8 for other pipe sections until the connection of multiple pipe sections constituting the gravity flow pipe is completed; Step S10, checking the sealing performance of the half joint, including: checking the gap size between the half joint and the pipe joint and the density of the sealing material; Step S11, backfilling the gravity flow pipe; Step S2-1 includes: step S2-1-1, sequentially setting a first position, a second position and a third position from the shore toward the lake surface; and setting a prefabricated pipe at each of the first position, the second position and the third position; Step S2-1-2, welding the prefabricated pipes arranged at the first position, the second position and the third position into one body, and setting the prefabricated pipes welded into one body as welded prefabricated pipes; Step S2-1-3, hoisting the welded prefabricated pipe to the lake surface, and reserving the first position, the second position and the third position for placing subsequent prefabricated pipes and welding them; Step S2-1-4, placing the subsequent three prefabricated pipes respectively at the first position, the second position and the third position; continuing to weld the end of the welded prefabricated pipe away from the lake surface with the prefabricated pipe located at the third position; Step S2-1-5, repeating steps S2-1-2 to S2-1-4, and continuing to weld other prefabricated pipes until the production of the first length pipe section and the second length pipe section is completed; Step S4, excavation of the gravity pipe foundation pit includes: step S4-1, using air suction and discharge method to remove the silt on the upper part of the lake bed, so as to excavate the upper part of the gravity pipe foundation pit; step S4-2, using impact crushing method to remove the rock on the lower part of the lake bed, so as to excavate the lower part of the gravity pipe foundation pit; the gravity pipe foundation pit is divided into 4 layers from top to bottom, and each layer is 1m high; the slope ratio of the gravity pipe foundation pit is a reverse slope of 1:2.5; step S4-3, underwater leveling of the gravity pipe foundation; Step S5, hoisting, comprises: Step S5-1, selecting hoisting points: the first floating crane sets two hoisting points at corresponding positions of 1 / 8 length and 3 / 8 length of the pipe section respectively; the second floating crane sets two hoisting points at corresponding positions of 5 / 8 length and 7 / 8 length of the pipe section respectively; Step S5-2, checking the hoisting stress and deformation; Step S5-3, welding the lifting lug; welding the lifting lug on the lifting point; the lifting lug comprises: a bottom plate, which is a plate-shaped object, has an arc that matches the surface of the pipe segment, and is welded on the surface of the pipe segment; The main board is a plate-shaped object with a hoisting hole in the center, and the main board and the pipe segment axis are arranged coplanar; The rib plate is a plate-shaped object, and the bottom surface of the rib plate is provided with an arc corresponding to the bottom plate; the rib plate is perpendicular to the bottom plate and the main plate, and is connected to the bottom plate and the main plate at the same time; one rib plate is provided on each of the left and right sides of the hanging hole; the rib plates are provided correspondingly on both sides of the main plate; Step S6, installing the lower half of the half, including: Step S6-1, placing the lower half of the half on the transport ship, Step S6-2, when the pipe section lifted by the first floating crane and the second floating crane stays at a height of about 1m on the lake surface, the third floating crane is used to lift the lower half of the half to the pipe section and connect it with the lifted pipe section; the center position of the lower half of the half is coplanar with the end face of the lifted pipe section to reserve a position for connection with the next pipe section; at the same time, a buoy is set on the top of the end face of the lifted pipe section to locate the joint position; Step S6-3, the transport ship leaves the lifting area, and the third floating crane is separated from the lifting; Step S7, sinking of the pipe segment, includes sinking the pipe segment using a straight line floating pipe sinking method: sinking the first end of the pipe segment, when the axis of the pipe segment is a straight line, by adjusting the lifting force of the first floating crane and the second floating crane and the amount of water injected into the pipe segment, the first end of the pipe segment is sunk to the bottom of the gravity pipe foundation pit, and then continuing to inject water to gradually sink the entire pipe segment into the gravity pipe trench; each pipe segment is connected head to tail in sequence.

2. The method for constructing a gravity flow pipe according to claim 1, characterized in that: The welding in step S2-1 includes: welding the butted prefabricated pipes by using carbon dioxide gas shielded welding; performing 100% flaw detection on the welding interfaces of the prefabricated pipes; and providing no less than 6 reinforcing steel plates at each welding interface.

3. The method for constructing a gravity flow pipe according to claim 1, characterized in that: Step S8, installing the upper half of the half section, including: Step S8-1, docking the upper half of the Haff and the lower half of the Haff: when the upper half of the Haff is lifted to the top of the pipe section by the third floating crane, the diver goes into the water to conduct underwater survey of the positions of the upper half of the Haff and the lower half of the Haff, and tightens the upper half of the Haff and the lower half of the Haff with an extended screw until the upper half of the Haff and the lower half of the Haff are completely docked; Step S8-2, removing the upper half of the Hough sling.

4. The method for constructing a gravity flow pipe according to claim 1, characterized in that: Step S10, checking the sealing of the half joint, includes: the diver tries to insert a steel ruler into the half joint; if the steel ruler cannot be inserted into the half joint, it means that the rubber ring is in close contact with the outer wall of the pipe joint; if there is still a gap after the steel ruler is inserted into the half joint, it means that there is a gap between the half joint and the pipe joint or the rubber ring is not in contact with the pipe joint.

5. The method for constructing a gravity flow pipe according to claim 1, characterized in that: Step S11, backfilling the flow pipe, includes: Step S11-1, using bagged gravel to protect both sides of the gravity pipe; Step S11-2, backfilling with sand and gravel; Step S11-3, backfilling with rocks, backfilling with rocks 500 mm above the top of the gravity pipe.

Images