Construction and supervision! Jiaojiang Wastewater Treatment Plant tail water deep sea discharge pipeline offshore operation construction plan Huang Huazhi Fanghu Xiaobian Jing 2 (1. Zhejiang Taizhou Water Treatment Development Co., Ltd., Taizhou 318000, Zhejiang; 2. China North China Design and Research Institute of Municipal Engineering, Tianjin 300074) The content of the course is on-land release pipelines, underwater release pipelines (underwater discharge pipelines along the coast, underwater vertical release pipelines), diffusers, risers, high-level wells, and structures on pipelines (pipe bridges, anchor-cable flexible foundations) Platforms, town piers, direct-buried expansion joints, insulated joints and retaining piles, etc.). Offshore pipelines are mainly composed of underwater discharge pipelines, underwater vertical discharge pipelines and diffusers. The length of the on-land discharge pipeline is 1 997m, the length of the underwater discharge pipeline is 1 765m, the length of the underwater vertical discharge pipeline is 834m, the length of the diffuser is 108m, and the total length of the pipeline is 4704m. The construction plan of the pipeline project is introduced in detail ,For. Platform; retaining piles Taizhou Jiaojiang Wastewater Treatment Phase II project tailwater deep sea discharge pipe discharge pipe, underwater discharge pipe, diffuser, riser, high-level road sewage discharge scale is 10X104m3 / d, and the project content is onshore wells and pipelines The structure (pipe bridge, anchor cable type flexible foundation platform, Zhenzhihai 1U.). Ocean Qin customs department handles customs I '. Procedures to collect water data. Topographical data and local data. Learn about setting back guides for back silting and Kyouji K structures. Set the water gauge. Create technical and private conditions for dredger operation. Before sweating, use GPS-RTK combined with sounding urum submarine mud pier, directly buried expansion joints, insulated joints and retaining piles, etc.). The sea discharge pipeline is composed of a land release pipeline, an underwater discharge pipeline, an underwater vertical discharge pipeline and a diffuser. The length of the onshore discharge pipeline is 1997m, the length of the underwater discharge pipeline is 1765m, and the length of the underwater vertical discharge pipeline is The length of the diffuser is 834m, the length of the diffuser is 108m, and the total length of the pipeline is 4704m. The onshore discharge pipe can be exchanged here from the L-584 to the high well stage and the second stage pipeline water body. The underwater discharge pipeline section starts from the high well and uses the pipe jacking method to cross the embankment in the direction of 20. With the north, the pipeline extends parallel to the embankment at a position 50m away from the foot of the embankment until it reaches the anchor cable-type flexible foundation platform (L3178 ). After the underwater vertical discharge steel pipe passes through the anchor cable-type flexible foundation platform, the vertical levee extends into the sea, and the pipeline spacing between the first and second phases is 60m. On each side of the anchor cable-type flexible foundation, a direct-buried expansion joint and insulating joints are provided. It is reinforced by geotextile and U-shaped load-bearing block at the Dingshun Dam, and finally reaches the underwater diffuser pipe section with anti-impact retaining piles. The diffuser of sea discharge pipeline adopts variable-section steel pipe, the length of the diffuser is 108m, the diameter of the diffuser is DN1 200, DN900 and DN600 respectively, the total number of spray holes on the diffuser is 32, that is, 10 is set on DN1 200 Nozzles, 12 nozzles on DN900, 10 nozzles on DN600, the nozzle diameter is 0.15m. 32 vertical pipes are welded on the diffuser pipe, the diameter is DN300, the thickness is 14mm, one DBO is set for each vertical pipe Type DN150 duckbill valve. The pipes are made of Q235B, the external anticorrosion of the underwater pipe adopts special reinforced grade epoxy coal asphalt, and the anticorrosion of the underwater pipe and all steel components adopt common grade epoxy coal asphalt. In addition to the internal and external anti-corrosion layers, the pipeline also uses electrochemical corrosion protection of the sacrificial anode. The anode material is aluminum-zinc-indium alloy zinc block. 1 Natural conditions, construction conditions and construction deployment The average annual temperature in the construction area is 16.6 ~ 17.3 ° C, the average annual maximum temperature is 21.2 ° C, and the average annual minimum temperature is 13.8 ° C. The rainfall is concentrated in two rainy seasons, namely 4 The rainy season in January-June and the typhoon period in July-October. Dominant wind direction: northeast wind in April and May, southwest wind in June-August, northwest wind throughout the year; annual average wind speed is 2.7m / s. Typhoon: annual average impact 1 ~ 2 times , Up to 3 to 4 times, the appearance season is generally from July to September, the earliest is May, and the latest is November. The project area of ​​the Jiaojiang sewage pipeline drainage section belongs to the coastal-river phase, and the sewage pipeline is located at the junction of the river and the sea. It is greatly affected by the hydrology of the Jiaojiang river water and sea tide. The flow direction is 295., the average low tide flow direction is 115 °; the average high tide seawater flow rate is 1.03m / s, the low tide seawater average flow rate is 0.81m / s; the annual average tide level is 2.22m. The pipe trench excavation layer is mainly silt, The local section is silty clay with silt, high natural water content, large void ratio and low bearing capacity. The sea discharge pipeline is laid along the edge of the industrial zone, the traffic is more convenient, the sea embankment is wider, and it can be used as a temporary storage site for steel pipes. The west of the seawall is an industrial zone, and it is impossible to open a construction site with a certain depth. The seawall is a relatively spacious floodplain, which is arranged as a steel pipe assembly welding site, but the Jiaojiang tidal range is large, which has a great impact on construction. The cement, steel, wood, gravel, etc. required for the project are supplied by the market, and the electricity and water for construction can be solved in the nearest place. The main work content of this project includes onshore drainage pipeline section, pipe bridge, high-level well, pipe jacking section, underwater onshore drainage pipeline, direct buried expansion joint, insulation joint, underwater vertical drainage pipeline section, anchor cable flexible foundation, offshore Diffusion pipe section, rising vertical pipe, anti-corrosion structure, foundation treatment, retaining piles, U-shaped block installation, protection tan, etc. This plan mainly considers the construction of underwater discharge pipelines, direct-buried expansion joints, insulated joints, underwater vertical discharge pipelines, anchor cable-type flexible foundations, offshore diffusion pipelines, rising vertical pipes, anti-corrosion structures, etc. The construction includes anti-corrosion of steel pipes, welding, hoisting, installation of ships on water, excavation on land, foundation treatment equipment for high-level wells, excavation of underwater foundation trenches, pipe jacking engineering, concrete engineering, transportation communication, and pressure testing for flaw detection. 2 Construction method for excavation of the foundation trench in the underwater vertical section 1 Process flow For the construction method of the excavation of the foundation trench in the underwater vertical section, see the pre-drainage survey on the axial section of the foundation trench, obtain first-hand information, and draw construction drawings to carry out on the mud dumping area Water depth measurement, reasonable use of dumping area to ensure the quality of dumping. Guide mark layout: Based on the axis of the base groove, the line marks on the left and right base groove sides are set, and the group center mark is set on the axis line, which can emit light at night. Two 2m3 grab bucket dredgers were used for the excavation of the pipeline foundation. The dredger adopts the construction from the far shore position along the trench axis to the near shore gradually, the anchor cable is laid, the bow anchor is aligned with the sea. For plane control, the intersection mark is established on the dam and the sextant rendezvous position with excellent performance is selected to control the position of the dredger. The differential beacon receiver and GPS "DGPS" technology are used to establish global positioning on the dredger. The system controls the construction ship position through the monitoring computer to improve the plane control accuracy. The bamboo poles are used to position the sections where the edge of the diversion channel has no effect on navigation. The construction positioning of this project is very important. For this purpose, the combination of "laser rangefinder, GPS and guide mark" is used to carry out construction plane control to ensure construction quality. The control of the plane position is combined by the dredger referring to the central guide and the theodolite installed on the shore, which can ensure the accuracy of the axis of the pipeline base slot. For in-depth control, a water reporting house is set up on the shore, that is, every tidal level rises and falls. 1m, report dredger with a high-frequency intercom. The operator on the dredger adjusts the excavation depth at any time according to the change of water level to ensure that the flatness of the base channel is controlled within the specified range. . When excavating, move slowly and steady, according to the dredging guide mark and the water gauge record to ensure that the axis of the foundation groove is accurate and the bottom of the groove is flat. Use mud barges and tugs to move the earth to the dump site and dump the dump. When excavating the foundation groove, a special person will conduct self-examination on the excavated foundation groove. The axis, width, depth, flatness and slope ratio of the foundation groove must meet the design requirements and be recorded for reference. After the excavation of the foundation groove is completed, acceptance shall be carried out in time. 2.3 Sand cushion construction After the underwater dredging work is completed and qualified, the sand cushion construction will be carried out. The quality of sand should meet the design requirements. According to the designed amount of sand pad, the vessel is moved forward along the base groove under the guidance of the land theodolite through the vessel, and the sand pad is thrown. According to the moving speed of the ship, the sand is metered onto the substrate, and then the sand pad is roughed and leveled with a leveling rake. At the same time, the divers make a coordinated inspection, and the slope, width, width, Thickness, flatness, etc. meet the design requirements to prevent the unevenness of the sand cushion from affecting the installation quality of the discharge pipe. 2.4 Construction requirements The foundation groove requires a flat surface without local protrusions or depressions, the axis of the foundation groove is consistent with the design axis of the pipeline, and the longitudinal slope meets the design requirements. Therefore, it is required to transfer the data such as position and depth clearly when the foundation trench is excavated, especially during the dredging shift to prevent the occurrence of missed excavation and partial line. The sand cushion must be level and the slope must conform to the design. The excavation depth of the foundation trough shall go through the sedimentation test of the foundation trough to determine the sedimentation rate, and adjust the original depth of the foundation trench excavation according to the sedimentation to prevent the sedimentation from affecting the construction quality of the foundation trough. 5 Geotextile foundation construction According to the requirements of the construction drawings, the underwater drainage pipeline L3730 uses underwater geotextile gravel to strengthen the foundation. Its structure is composed of geotextile and geogrid, and the sand and stone cushion layer are laid on it to form a continuous overall foundation. The laying of geotextiles is carried out by combining the laying of ships on water and the underwater inspection of divers. Before laying, set the geotextile laying edge guide on the shore; when laying, the axis is reviewed with the theodolite at any time to ensure that the laying axis and edge are accurate. During the laying process, pay special attention to the following items: when laying, the continuity of the geotextile laying should be ensured, the joints should be firmly lapped, without twisting and wrinkling, and be even and even. When pressing the stone layer, it should be compacted. The flake content of the flake sand cushion is 70%, the particle size is 350g / m2, the thickness is 3mm, and the width is 7.5m. The tensile strength in the warp direction is 500N / 5cm, and the tensile strength in the weft direction is 600N / 5cm. , Warp elongation is 30% ~ 80%, weft elongation is 30% ~ 60%; warp trapezoid tear strength 300N, weft trapezoid tear strength 500N, permeability coefficient (1.4 ~ 1.9) x102cm / s. The lap thickness of the adjacent geotextile and the anchoring of the geotextile at both ends should meet the requirements. No folding or breakage shall occur during the laying of geotextiles. 3 Construction method for excavation of foundation trenches along the shore in the underwater area 1 The guide marks for foundation trench excavation are set based on the axis of the foundation trench, and a pair of line markers are set on the left and right sides of the foundation trench respectively. A group of central markers are set on the axis and glow at night. Since the onshore pipeline section is located in the tidal flat section, it is greatly affected by the tidal range and the water level is shallow. The construction of large dredgers is inconvenient. This project uses two self-propelled hydraulic backhoe dredgers and is equipped with mud barges. 3.2 Excavation section requires excavation section to show opinions Excavation section 4 Construction method of offshore release pipe 4.1 The length of the lower pipe section of the long pipe section and the vertical sloping section of the lower section is 942m, and there are two sections of the lower section of the downstream section which are 900m and 865m, the launching work is one of the key tasks. Due to the length of the pipe section, high linear requirements, local deformation is not easy to control, and the shape of the discharge pipe is special, improper control can easily cause permanent defects such as torsion and excessive local deformation, which affects the project quality. Larger. In view of the above situation, the use of on-site conditions and the tide of Haimen Port, the use of flexible pipe pads above the high tide level for pipeline splicing operations, to avoid the impact of tides on pipeline assembly welding, the use of flexible pipe pads when the beach is adjusted The spliced ​​and assembled pipeline is launched into the water and floats to the beach to ensure the safety of the pipeline. 2 After the assembly of the long pipeline section of pipeline water haulage is completed, the climatic conditions with little wind and waves are selected. At high tide, the pipeline is already in a floating state. At this time, the pipeline is towed by the tugboat to the installation axis position. Before hauling, set several control cable points in the middle and the end of the pipeline section, configure 8-10 tugboats, lead the hauling cable to each hauling vessel, and gently haul the pipeline section out of the water at the highest tide level. When the steel pipe goes to the beach, the hauling vessels will command and coordinate actions to ensure the safety of construction and the launching of steel pipes. The pipeline is towed slowly after going to the beach. In addition to the main towing vessel, the towing vessel in the middle and the end controls the floating state of the pipe section in the water at any time according to the direction of the water flow. The pipeline is subject to water flow during the floating movement, which is easy to bend the pipeline Deformation, calculate the allowable bending radius and limit vector height of the pipeline before construction, track and observe the bending vector height during floating transportation, and communicate with each hauling ship in time to make appropriate adjustments. When hauling, choose the appropriate weather and conditions such as flat tide or slow tide, especially for slow-speed counter-current haulage to make the pipe section float straight as much as possible. The control cable points of the haulage pipe section are arranged according to the force calculation data of the pipe section, so that the pipe section is evenly stressed during the floating transportation process. After the long pipe section is in place, use the calculated short jacks and shackles to lock the pipe section and the positioning pile in time to eliminate the lateral deflection of the steel pipe and eliminate the drift of the water flow on the pipe. 4.3 The total length of the steel pipe in the vertical bank section is 942m, and it is greatly affected by the impact of the lateral water flow during the settlement process (according to the maximum horizontal current velocity of 1.03m / s, the maximum lateral force experienced by the pipeline) It is 350kN / m), so it is necessary to take measures for the lateral positioning and stability of the pipeline. After calculation, it is determined to take the setting pile method. Specifically, a 0300mm steel pipe is set every 40m, and the depth is 15m. Another configuration 5 A sinking ship (too many sinking ships is not conducive to the control of pipeline shape and stress). The sinking ship is anchored and positioned at the sinking position under the control of the land theodolite and the rangefinder, and the vertical pipeline installation axis throws a figure eight anchor. When laying the pipe section, the shape and stress of the pipe section should be well controlled, and the stress of the pipe section should be controlled within 120MPa. After calculation, 2 floats / m of light floats are arranged along the pipeline (after adjusting the quality of the steel pipe, the underwater mass is 20kg / m) to cooperate with the construction of 5 sinking ships. Bobber. See the specific layout. Under the control of the land theodolite and the total station, the position of the pipe section is adjusted by positioning the cable and the lifting vessel, so that the pipe section and the installation axis and installation position of the pipeline exactly match. After the pipeline position adjustment is completed correctly, open the inlet valve and exhaust valve at both ends of the pipeline, the inlet near the shore, the exhaust at one end of the discharge port, 5 cranes and control cables coordinate the natural water intake of the pipe section, at this time the pipe section Maintain a proper position and shape, so that the pipe section is exhausted smoothly at the other end when entering the water, to prevent the occurrence of air resistance and water hammer. During the sinking process of the pipeline, the crane vessel mainly controls the shape of the pipeline, and the stress control of the pipeline is achieved by quality adjustment. When the pipeline sinks close to the crane vessel, each crane vessel can coordinate the sinking of the pipe section and control the sinking speed. At the same time, the hooks of the 5 crane vessels coordinate with each other to make the pipeline sink evenly, and the pipeline is controlled by force Within the allowable range. At this time, the land theodolite constantly reviews the axis position of the pipeline to ensure that the pipeline can be accurately positioned. After the pipe section sinks, the diver on the diving work boat immediately launches to conduct underwater inspection and treatment of the pipe section. Good strength. If any special problems are found, contact the surface command ship in time and study the treatment methods. If no harmful phenomena are found in the underwater inspection, the quality regulator should be removed as soon as possible to complete the sinking work of this pipe section. Do the following during and after the pipeline sinking process: ①The installation requirements and errors of the underwater pipeline should be strictly enforced; ② The stress and deflection during sinking should be strictly controlled according to the calculated data to ensure that it is within the allowable range ; ③ When the pipe section is laid, the influence of tidal currents, wind and waves must be considered, and detailed measures for adverse emergencies must be worked out; ④ natural water should be closely coordinated to prevent the air resistance from sinking difficulties or even sinking the pipe; ⑤ pipe section Pay attention to the verticality of the pipe section when sinking, so as not to affect the normal use of the diffuser. After the sinking pipe is in place, the pipe is stabilized immediately. According to the design, the pipe is backfilled to the design elevation with sand, and then sand bags and gravel are thrown on it. position. Retaining piles should keep their shape vertical during the sinking process to prevent tilting and damage to the pipeline. After the retaining pile is driven into the design elevation, the diver will launch the anchor and connect the retaining pile to the pipeline. 4.5 Underwater throwing sand bags and gravel bags The offshore pipe section needs underwater throwing sand bags and gravel bags, and geotextile bags are used to fill the sand and gravel. Each bag is filled with 1/2 volume of sand, loaded into place, hung into the water, and stacked by the divers. During the construction of this process, the slope and elevation are designed in strict accordance with the drawings, so that the stack is stable, the slope angle is large, and the slope is stable; at the same time, the layer-to-layer, bag-to-bag tight fit is achieved. Strictly control the quality of the material. After the sandbag is thrown and filled, pass the depth sounder or rope measurement to measure the self-test in time, and immediately correct the unqualified section until it meets the design requirements. After the sand bag is filled, the stone bag is filled. Before throwing the gravel bag, pay attention to whether there is silt on the surface of the sand bag. When the back silting is large, use a high-pressure water gun to clear the silt and then throw the fill. The throwing and filling of the gravel bags are laminated one by one, and the layers are closely attached to achieve the construction purpose. The size of the crushed stone is 3 ~ 6cm, the grade is good, the stone is non-strong weathered stone, the mud content does not exceed 4.6 vertical pipe stubs, elbows and duckbill valves. And duckbill valve installation. Before installation, the diving work boat is in position at the standpipe. The divers go into the water to remove the standpipe blind plate, install the flange pad, and divers will escape from the water. The diver will launch again, pierce the fixing bolts, and instruct the lifting equipment on the diving work boat to adjust the position of the short tube until the screw holes of the two flanges are centered, the flanges are flat, and the divers pierce the connecting bolts as required ( Diagonal, uniform) tighten. The flange elbow and duckbill valve are pre-assembled on land with the vertical pipe stub, so that the vertical pipe stub, elbow, and duckbill valve can be installed at once under water. Work in sequence to complete the installation of all vertical pipe shorts, elbows and duckbill valves. 4.7 Settlement and installation along the bank section The total length of the pipeline along the bank section is 1 765m, which is divided into two sections for assembly. After the pipe section is floated to the axis position, the two sections of pipe are spliced ​​into a whole by a water buoy and then submerged. The installation of the anchor cable-type flexible foundation platform shall be carried out after the settlement of the underwater vertical pipe and the underwater downstream pipe. At the time of installation, use a 50t gondola to hoist one end of the underwater shore pipe platform and connect it to the platform hung by the 200t gondola (the bent pipe has been installed after the platform is prefabricated). After the connection is completed, use the 50t gondola to move the underwater One end of the shore pipe platform is hoisted, and then connected. After the connection is completed, the platform is installed in place. The divers launch the steel anchor chain to connect the platform and the steel anchor pile underwater. 5 Conclusions When constructing offshore pipelines for offshore operations, the topographical characteristics, geological conditions, marine environment and local climatic environment of the project site should be combined, on the premise of ensuring safety and quality, through the collection of a large number of original data, site survey Only by formulating economic and reasonable construction methods can the project be successfully completed. Ice Mold Serices,Ice Ball Maker,Ice Cube Tray,Ice Ball Mold SY INTERNATIONAL (CN) CO.,LTD , https://www.symanufactures.com
Construction Scheme for Offshore Operation of Tail-water Deep-sea Discharge Pipeline of Jiaojiang Wastewater Treatment Plant