Ultra-deep diaphragm wall ultra-long slot section trenching construction system and trenching construction method thereof

Abstract

The application provides a kind of ultra-deep diaphragm wall ultra-long slot section trenching construction system and trenching construction method thereof, including mud recycling system=mud recycling system includes desander, desander is communicated with hydraulic milling internal booster pump, the liquid outlet of desander is communicated with multiple desanders respectively, the slag outlet of desander and desander is communicated with purification station storage tank, the liquid outlet of desander is communicated with purification station storage tank, purification station storage tank is recycled by centrifugal filter inside, and purification station storage tank is communicated with trenching by first pump body.The reasonable configuration and application of underground diaphragm wall mud can form a good mud skin, effectively ensure the stability of diaphragm wall slot wall, remove the sediment, soil debris and other sundries in the hole, speed up the trenching efficiency, and ensure the smooth trenching of machinery.At the same time, in order to improve the efficiency of mud use and reduce the amount of waste mud disposal, mud is generally purified and recycled, and the recycling efficiency is also the key to control.

Description

Technical Field

[0001] This invention relates to the field of trenching construction, and in particular to a trenching construction system and method for ultra-deep diaphragm wall ultra-long trench sections. Background Technology

[0002] In locations with abundant groundwater, trenching for diaphragm walls in sandy layers presents a significant risk of groundwater influx when the trenching passes through these layers. This influx could dilute the slurry used to protect the walls, jeopardizing the stability of the trench walls. Therefore, the milling method and slurry mix design must be carefully considered when trenching through sandy layers. Slurry wall protection technology is a fundamental technology in diaphragm wall engineering, and its quality directly impacts the quality and safety of the diaphragm wall, making it a crucial measure for ensuring successful construction. Properly configuring, calculating, and proportioning the slurry can lead to low slurry utilization efficiency, large waste slurry disposal volumes, and low recycling efficiency.

[0003] Currently, research on multi-segment trenching technology for diaphragm walls based on a combination of grabbing and milling is underway. To ensure the cleanliness of the trench bottom and the quality of subsequent wall pouring, a synergistic trenching technology supplemented by pulsed water flow positive circulation is being studied, building upon reverse circulation airlift trenching. Chinese patent CN 111042136 B describes a combined device for secondary cleaning of diaphragm wall trench segments using a pouring guide pipe. However, this device is only suitable for trenches with thin sediment layers; when sediment exceeds 50cm, the cleaning time is long and the cleaning effect is poor. Furthermore, the construction method for trenching diaphragm walls in soft soil areas disclosed in Chinese patent CN101289853A has poor adaptability to different strata, and trenching efficiency is greatly affected by the strata. Additionally, conventional trench segments are generally no more than 6m long, resulting in short segments, numerous joints, and a high risk of joint leakage. Summary of the Invention

[0004] The main objective of this invention is to provide a trenching construction system and method for ultra-deep diaphragm wall ultra-long trench sections, thereby solving the problems in the construction of diaphragm wall projects.

[0005] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is: an ultra-deep diaphragm wall ultra-long trenching construction system, including a mud recycling system. The mud recycling system includes a desander, which is connected to the internal lifting pump of the hydraulic milling machine. The outlet of the desander is connected to multiple desanders respectively. The slag outlets of the desander and the desanders are connected to the purification station storage tank. The outlet of the desander is connected to the purification station storage tank. The interior of the purification station storage tank is circulated and cleaned by a centrifugal filter. The purification station storage tank is connected to the trenching section through a first pump body.

[0006] In the preferred embodiment, the centrifugal filter inlet is connected to the purification station storage tank via a second pump body, and the centrifugal filter outlet is also connected to the purification station storage tank.

[0007] In the preferred embodiment, the mud raw material warehouse is connected to the mud storage tank through the mud preparation station, and the mud storage tank is connected to the purification station storage tank through the second pump body.

[0008] In the preferred embodiment, the mud storage tank is composed of multiple stacked tanks, with the tanks decreasing in size from bottom to top.

[0009] In the preferred embodiment, the construction system also includes a secondary cleaning system: including at least two conduits, one end of which is placed in the trench and the other end is connected to the lifting device. The top of the first conduit is connected to the end cap of the three-way structure, the upper end of the second conduit is connected to the grout inlet pipe, the grout outlet on one side of the end cap pipe is connected to the desander, and the liquid outlet of the desander is connected to the grout inlet pipe. The first conduit also has an inner tube inside, with the lower end of the inner tube close to the lower opening of the first conduit, and the other end passing through the top of the end cap and connected to the air pump.

[0010] In the preferred embodiment, the top of the first conduit is connected to the first winch, and the top of the second conduit is connected to the second winch.

[0011] In the preferred embodiment, the second winch is a double-rope double-drive winch, and the two hoisting ropes of the second winch are respectively hinged to the top two sides of the second guide tube; The different winding speeds of the dual-rope winch allow the lower end of the second guide tube to swing.

[0012] In the preferred embodiment, the top of the first guide tube is also provided with a fixing seat, which includes a fixing plate. The fixing plate is set on the top of the end cap tube. A conical through hole is provided in the middle of the fixing plate. The inner tube passes through the conical through hole. Multiple conical arc plates are also provided. The multiple conical arc plates are spliced ​​around the outer surface of the inner tube and fit against the outer surface of the inner tube. The outer surface of the multiple conical arc plates forms a cone structure. The cone structure is stuck on the conical through hole in the middle of the fixing plate.

[0013] In the preferred embodiment, the tops of adjacent conical arc plates are connected by a synchronous plate. The top of the conical arc plate is also provided with a limiting pin. The synchronous plate is provided with a waist-shaped hole. The limiting pin passes through the waist-shaped hole, and the limiting plate at the upper end of the limiting pin abuts against the upper surface of the synchronous plate.

[0014] Trenching construction methods include: S1. Use plaxis 3d software to model the geological conditions of the entire trenching location. Based on the specific gravity of the mud, simulate the stability changes of the trench wall under actual working conditions at the trenching location. Set the positions of the milling machine and the crane. Use plaxis 3d software to analyze the deformation and settlement of the trench. Observe the deformation cloud map of the milled trench wall during the trenching construction. S2. Based on the analysis of the above-mentioned Plaxis 3D software, the specific gravity and viscosity of the mud are obtained, and composite standard mud is prepared. S3. The raw materials inside the mud raw material warehouse are mixed by the mud preparation station and then transported to the mud storage tank. The mud storage tank is transported to the purification station storage tank by the second pump body. The purification station storage tank is transported to the tank by the first pump body. S4. The drilling mud in the slot is pumped to the desander by the mud pump in the milling head. The drill cuttings larger than 5mm in the mud are screened out by the vibrating coarse screen. The treated mud is then transported to the desander to separate the fine sand larger than 0.06mm in the mud. The screened sand is transported to the slag collection pit by the conveyor belt. The mud after secondary treatment is transported to the purification station storage tank for storage. S5. The slurry inside the storage tank of the purification station is treated by a horizontal screw discharge sedimentation centrifugal filter. The centrifugal force is used to separate fine particles larger than 0.03mm in the slurry. After treatment, the slurry is returned to the tank. S6. A combination of hydraulic milling and hydraulic grab bucket is used to form the trench. The upper grab bucket forms the trench to the soft soil layer, and the lower milling forms the trench. After entering the hard soil layer, a hydraulic milling machine is used to mill until the final hole is reached. Then, mud circulation is used to clean the hole. After the trench is completed and accepted, a combination of hydraulic milling and mud purification system is used to clean the hole and change the mud. S7. The hydraulic grab bucket is used to grab the soil on both sides of the trench section divided at the construction location in the following steps: grab the soil in the center first. A soil layer is left between the trench holes after each grab. The trench is measured with an ultrasonic inclinometer to observe the integrity of the trench. Fresh mud should be continuously injected into the trench during the trenching process. S8. After the trenching construction is completed, the steel cage is hoisted into the trench. The first guide pipe is lowered using the first winch. The lower end of the first guide pipe is lowered to a position of 40-50cm from the bottom of the trench. A three-way end cap is installed on the first guide pipe. The slurry outlet of the end cap is directly connected to the sand removal machine. Then, the second guide pipe is lowered using the first winch. The lower end of the second guide pipe is lowered to a position 30-40cm below the bottom of the trough. A slurry inlet pipe is installed on the second guide pipe, and the slurry inlet pipe is connected to the desander through the pump body. Multiple tubes are joined together to form an inner tube, which is placed inside the first guide tube. The lower end of the inner tube is close to the lower end of the first guide tube, and the upper end of the inner tube is fixed by a fixing seat. The lowering depth of the inner tube is adjusted according to the cleaning time. S9. The air pump injects high-pressure air into the first guide pipe. Under the action of high air pressure, the mud between the inner pipe and the first guide pipe forms a circulation, and the sediment at the bottom of the tank is discharged through the slag discharge pipe along the gap between the inner pipe and the casting guide pipe. The sludge discharged through the sludge discharge pipe can be either directly discharged into the sedimentation tank for sedimentation or sent to a mud desanding machine for purification. After the mud is purified, the solid waste is transported away directly, and the mud flow is transported back to the tank through a high-pressure jet pump. S10. Control the winding reel at one end of the second winch to be fixed, and the winding reel at the other end to start lifting and then lowering, so that the second guide pipe starts to swing inside the trough. The second guide pipe stirs up a large amount of sediment, and most of the stirred sediment is discharged from the first guide pipe. S11. During the hole cleaning process, as the sediment at the bottom of the hole decreases, the first and second guide pipes are promptly lowered and poured. During the slag removal process, mud is promptly added to the hole. S12. During the adjustment of the inner tube, the inner tube position is locked by the cooperation of the tapered arc plate and the tapered through hole on the fixed plate, which can adjust the position and depth of the inner tube.

[0015] This invention provides a construction system and method for constructing ultra-deep diaphragm wall ultra-long trench sections. The rational configuration and application of diaphragm wall slurry can form a good mud cake, effectively ensuring the stability of the diaphragm wall trench wall, removing sediment, soil debris, and other impurities from the borehole, accelerating trenching efficiency, and ensuring smooth mechanical trenching. Simultaneously, to improve slurry utilization efficiency and reduce waste slurry disposal, the slurry is generally purified and recycled; its recycling efficiency is also a key focus of implementation and control.

[0016] The "grip-milling combined" construction method not only leverages the advantages of hydraulic trenching machines in soft clay strata—fast trenching speed, high precision, and minimal mud pollution—but also avoids the drawbacks of twin-wheel milling machines, such as wheel clogging and excessive waste slurry generation in this layer. Simultaneously, it utilizes the speed advantage of twin-wheel milling machines in deep, pebble, and rock strata. Combining these two techniques significantly improves the trenching efficiency of individual sections, greatly shortens the time required for continuous trenching of ultra-long trenches, and reduces the risk of trench wall collapse.

[0017] The secondary hole cleaning device of this application has a simple structure and is easy to operate. When performing secondary hole cleaning, only the inner tube, the end cap and the guide pipe sealer need to be installed. After the hole cleaning is completed, only the inner tube, the end cap and the guide pipe sealer need to be removed before underwater concrete pouring can be carried out in the trench section. High-pressure gas mixes with mud inside the conduit to form a large number of mud bubbles with low specific gravity. Due to their low specific gravity, the mud bubbles rise and create a negative pressure at the bottom of the mixer inside the conduit. Under the action of negative pressure, the mud at the bottom of the tank below the conduit carries the sediment out of the conduit. Mud is continuously replenished outside the tank section, forming a reverse circulation of mud, thereby achieving the bottom cleaning effect. Attached Figure Description

[0018] The present invention will be further described below with reference to the accompanying drawings and embodiments: Figure 1 This is a schematic diagram of the mud recycling system of the present invention; Figure 2 This is a flowchart of the mud recycling system of the present invention; Figure 3 This is a schematic diagram of the construction process of the grab-milling combination of the present invention; Figure 4 This is a schematic diagram of the combined slag removal and emptying process of the present invention; Figure 5 This is a front view structural diagram of the fixing base of the present invention; Figure 6 This is a top view of the fixed base of the present invention.

[0019] In the diagram: 1. Hydraulic milling machine; 2. First pump body; 3. Slag collection pit; 4. Purification station storage tank; 5. Second pump body; 6. Centrifugal filter; 7. Second pump body; 8. Slurry storage tank; 9. Slurry preparation station; 10. Slurry raw material warehouse; 11. Desander; 12. Desander; 13. First guide pipe; 14. Second guide pipe; 15. First winch; 16. Second winch; 17. Slurry inlet pipe; 18. End cap pipe; 19. Fixed seat; 1901. Fixed plate; 1902. Conical arc plate; 1903. Synchronous plate; 1904. Limit pin; 20. Inner pipe; 21. Air pump. Detailed Implementation

[0020] Example 1 like Figures 1-6 As shown, a construction system for ultra-deep diaphragm wall ultra-long trench sections includes a mud recycling system. The mud recycling system includes a desander 12, which is connected to an internal lifting pump of a hydraulic milling unit 1. The outlet of the desander 12 is connected to multiple desanders 11. The slag outlets of the desander 12 and the desanders 11 are connected to a purification station storage tank 4. The outlet of each desander 11 is connected to the purification station storage tank 4. The purification station storage tank 4 is circulated and cleaned by a centrifugal filter 6, and is connected to the trenching section via a first pump body 2. The inlet of the centrifugal filter 6 is connected to the purification station storage tank 4 via a second pump body 5, and the outlet of the centrifugal filter 6 is also connected to the purification station storage tank 4. A mud raw material warehouse 10 is connected to a mud storage tank 8 via a mud preparation station 9, and the mud storage tank 8 is connected to the purification station storage tank 4 via a second pump body 7.

[0021] During the milling and drilling process, the soil is broken up by the milling wheel. The broken soil blocks are carried by the mud in the hole to the mud purifier. At this time, the mud specific gravity is above 1.35 g / cm3, the viscosity is above 35 seconds, and the sand content is between 8% and 10%. Different strata and milling speeds cause large fluctuations in the slurry performance parameters. The soil-containing mud is transported to the vibrating coarse screen through the purifier feed pipe. Due to the long screen distance and certain inclination, coupled with the vibration, soil particles larger than 5 mm are filtered out. The mud can quickly separate from the solid particles and leave the screen area without a large loss of mud.

[0022] Mud particles smaller than 5mm enter the flow distributor and then flow through the connecting pipe into the main tank of their respective desanders. The mud is pumped to the hydrocyclone separator. When the mud enters the equipment tangentially from the desander inlet under a certain pressure, it generates a strong rotational motion. Due to the different densities of sand and water, under the action of centrifugal force, centripetal buoyancy, and fluid drag, the lower density water rises and flows out from the overflow port, storing in the mud tank. The separated fine sand particles (greater than 0.06mm) fall from the bottom hole of the hydrocyclone onto the vibrating dewatering screen. The treated mud is collected in the intermediate tank through the overflow hole of the hydrocyclone and then transferred to the outer tank. At this point, the treated mud still contains a large number of fine particles. The specific gravity of the slurry should be maintained above 1.35, the viscosity (Marsh viscosity) should be maintained above 37S, and the sand content should be maintained at 8%.

[0023] Part of the slurry in the outer tank is pumped to a horizontal screw discharge sedimentation centrifuge. The slurry is added into the screw through the feed pipe, and then enters the drum through the discharge hole inside the screw cylinder. Under the action of centrifugal force, the heavier solid particles settle on the drum wall, forming an annular solid layer. The screw conveyor, under the action of the differential, pushes the dewatered solid sludge (particles larger than 0.03mm, with a minimum of 5μm) out of the slag outlet of the conical drum, while the lighter slurry overflows from the overflow port. This continuous operation achieves the purpose of continuously separating fine particles from the slurry.

[0024] After purification, the mud's specific gravity is reduced to below 1.25 g / cm3, its viscosity to around 33 seconds, and its sand content to below 1%. It is then directly pumped into the trench to replenish the mud pumped out from the bottom of the trench, achieving the purpose of mud recycling.

[0025] In the preferred embodiment, the mud storage tank 8 is composed of multiple stacked tanks, with the tanks decreasing in size from bottom to top. The mud storage pool consists of three layers of steel boxes of progressively smaller size, assembled and welded from steel plates, steel plate reinforcing ribs, and I-beam supports, and is divided into a slurry preparation tank, an expansion tank, and a recycling tank. The mud storage tank is equipped with a mud circulation pipeline to prevent mud from settling. The mud tanks are connected by pipes and gate valves, allowing for individual or group use. Stacking the three tanks greatly reduces the requirements for the construction site, minimizing the impact on surrounding residents and the environment. Furthermore, the mud tanks are easy to disassemble and assemble; after disassembly, the smaller upper tanks can be nested into the larger lower tanks, making transportation extremely convenient.

[0026] Example 2 Further explanation in conjunction with Example 1, such as Figure 1-6The structure shown was modeled using Plaxis 3D software to depict the geological conditions of the entire trenching location. Based on the specific gravity of the slurry, the stability changes of the trench wall under actual working conditions were simulated at the trenching location. The positions of the milling machine and crane were set, and Plaxis 3D software was used to analyze the deformation and settlement of the trench. The deformation cloud map of the milled trench wall was observed during the trenching construction. Based on the analysis of the above Plaxis 3D software, the specific gravity and viscosity of the slurry were obtained, and composite standard slurry was prepared.

[0027] To maintain the stability of the trench walls during the trenching and reinforcement cage installation processes of the ultra-long trench section, the mud slurry needed to be studied. Plaxis 3D software was used to model the entire geological condition, assuming the mud slurry specific gravity remained stable at 1.1. By adding additives such as heavy metal powder, the mud slurry specific gravity was adjusted to 1.1, and its stability was maintained for more than 8 days. Finally, based on full-scale model tests, the prepared slurry was applied to a full-scale model in the field. The mud slurry in the full-scale model remained basically stable within 8 days, and there was no collapse of the trench walls.

[0028] By modeling geological conditions, the stability changes of the trench wall under actual working conditions are simulated.

[0029] Working Condition 1: Simulate the milling of a long, straight groove section 7. The milling machine used is a BC40 milling machine. Based on the actual working conditions of the milling machine, the load is applied uniformly to the tracks.

[0030] Under this working condition, the distances between the milling machine and the edge of the trench are 2m and 5m respectively. The loads are distributed on the two tracks in a 3:7 ratio. The total weight of the milling machine is 180t. The loads distributed on the two tracks are 54t "away from the trench section side" and 126t "close to the trench section side". The uniformly distributed loads are used to simulate the forces transmitted to the soil by the two tracks.

[0031] Working condition 2: After the simulated trench is formed, the crawler crane lifts the steel cage from the side of the trench section.

[0032] Under this working condition, the crane is a side-lifter. When the steel box is lowered, the distance between the track and the edge of the trench is 5m and 12m respectively. According to the lifting position, the load applied to the two tracks is distributed in a 3:7 ratio. The self-weight of the steel cage is 150t, and the weight of the 500t crawler crane is 365t. Therefore, the total weight is 515t. The loads distributed on the two tracks are 155t - away from the trench section and 360t - close to the trench section. The uniformly distributed load is used to simulate the force transmitted to the soil by the two tracks.

[0033] When hoisting the steel cage, the trench has already been dug and filled with wall-protecting mud. The mud is applied according to the fluid load, and the mud specific gravity is 1.1.

[0034] According to the calculation results, the mud with a specific gravity of not less than 1.1 should maintain stable performance for 8 days.

[0035] To ensure that other performance indicators of the mud are maintained, through research and experiments on additives, barite BaSO4, CMC and sodium carbonate were used as additives, which can effectively increase the mud specific gravity, control the mud viscosity and sand content, increase mud stability and reduce water loss.

[0036] Through further proportioning experiments, the optimal mud mix ratio was determined to be water: bentonite: CMC: sodium carbonate: barium sulfate = 1000: 2: 20: 30. If the content of the admixture BaSO4 is further increased, the colloid content of the mud will decrease and the mud cake thickness will increase.

[0037] Example 3 Further explanation in conjunction with Example 1, such as Figure 1-6 As shown in the structure, the raw materials inside the mud raw material warehouse 10 are mixed by the mud preparation station 9 and then transported to the mud storage tank 8. The mud storage tank 8 is transported to the purification station storage tank 4 by the second pump body 7. The purification station storage tank 4 is transported to the tank through the first pump body 2. The drilling mud in the slot is pumped to the desander 12 by the mud pump in the milling head. The drill cuttings larger than 5mm in the mud are screened out by the vibrating coarse screen. The treated mud is then transported to the desander 11 to separate the fine sand larger than 0.06mm in the mud. The screened sand is transported to the slag collection pit 3 by the conveyor belt. The mud after secondary treatment is transported to the purification station storage tank 4 for storage. The slurry inside the purification station storage tank 4 is treated by a horizontal screw discharge sedimentation centrifugal filter 6, which uses centrifugal force to separate fine particles larger than 0.03mm in the slurry. After treatment, the slurry is returned to the tank. During construction, the equipment configuration and power consumption should be determined and adjusted based on the milling and drilling speed and construction efficiency to ensure sufficient slurry delivery. The slurry level in the trench should be 1.5m above both the groundwater and surface water levels to maintain pressure balance within the trench section. To ensure rapid and efficient slurry purification during diaphragm wall drilling, the slurry processing capacity of each level of purification equipment should match the slurry pump discharge rate in the milling head. Based on this, unit-based operation can be adopted to continuously process the drilling slurry in the trench while drilling, simultaneously with normal milling and drilling, ensuring that the slurry's specific gravity, viscosity, and other performance parameters consistently meet construction requirements during the trenching process. When the slurry properties are stable, the operation of the centrifuge unit in the slurry purification system can be appropriately reduced or shut down to minimize equipment wear.

[0038] Example 4 Further explanation is provided in conjunction with Examples 2-3, such as Figure 1-6The structure shown uses a combination of hydraulic milling and hydraulic grab bucket to form a groove. The upper grab bucket forms a groove to the soft soil layer, and the lower part is milled to form a groove. After entering the hard soil layer, a hydraulic milling machine is used to mill until the final hole is reached. Then, mud circulation is used to clean the hole. After the groove is completed and accepted, a combination of hydraulic milling and mud purification system is used to clean the hole and replace the mud. The hydraulic grab bucket is used to grab the soil on both sides of the trench in the construction location first, and then grab the soil in the center. A soil layer is left between the trench holes after each grab. The trench is measured with an ultrasonic inclinometer to observe the integrity of the trench. Fresh mud should be continuously injected into the trench during the trenching process.

[0039] Verticality and aperture shape inspection: The DM604 ultrasonic inclinometer from KODEN Corporation of Japan was used for measurement.

[0040] "Grab-milling combination" refers to a construction method where the upper overburden layer of the diaphragm wall is constructed using a grab bucket, while the sand layer and bedrock are constructed using a twin-wheel milling machine. This method leverages the advantages of hydraulic trenching machines in soft clay strata—fast trenching speed, high precision, and minimal mud contamination—while avoiding the drawbacks of twin-wheel milling machines, such as wheel clogging and excessive waste slurry production in these layers. Simultaneously, it utilizes the speed advantage of twin-wheel milling machines in deep, gravelly, and rock strata. Combining these two technologies significantly improves the trenching efficiency of individual sections, greatly shortens the time required for continuous trenching of ultra-long trenches, and reduces the risk of trench wall collapse.

[0041] Hydraulic milling generally requires the use of an odd number of milling operations, i.e., one milling operation to form a groove, three milling operations to form a groove, and five milling operations to form a groove.

[0042] When constructing the small wall, the left and right correction plates of the hydraulic milling machine are ineffective. The milling head's excavation posture is maintained solely by the front and rear correction plates and the weight of the milling head. At this time, the width of the small wall will determine the speed and quality of trenching. Based on past construction experience, the width of the small wall should ideally be 0.6~1.4m. If the small wall is less than 0.6m, it may collapse during the second milling, causing the second milling to deviate from the first. If the small wall is greater than 1.4m, controlling the milling head's posture becomes difficult, and the construction speed will be significantly reduced. Therefore, when the first-stage trench section is formed using one milling operation, the trench width should be 2.8m; when three milling operations are used, the trench width should ideally be 6.2m~7.0m; and when five milling operations are used, the trench width should ideally be 9.4~11.2m.

[0043] During the construction of each continuous wall, the soil on both sides is grabbed first, and then the soil in the center is grabbed to prevent uneven force on both sides of the grab bucket from affecting the verticality of the trench wall.

[0044] When lowering the grab bucket to excavate, align the center of the grab bucket with the center marker of the hole placed on the guide wall, and lower it along the outer side of the guide wall to ensure accurate excavation position. Do not fill the bucket completely; that is, do not fill each bucket with soil, because the soil, after being compressed in the mud, will affect the quality of the mud, increasing its viscosity and specific gravity.

[0045] During trenching, fresh mud should be continuously injected into the trench, maintaining the mud level 1m above the groundwater level and no less than 0.3m below the top of the guide wall. The mud quality should be checked regularly, and adjustments made as needed to meet the above specifications and the requirements of special geological formations. If the mud level in the trench is found to have decreased or the concentration to have thinned, it should be immediately determined whether this is due to groundwater inflow or mud loss with groundwater, and appropriate corrective measures should be taken to ensure the trenching process can continue normally.

[0046] Example 5 Further explanation is provided in conjunction with Examples 2-3, such as Figure 1-6 The structure shown in the figure also includes a secondary cleaning system: including at least two conduits, one end of which is set in the trench and the other end is connected to the lifting device. The top of the first conduit 13 is connected to the end cap 18 of the three-way structure. The upper end of the second conduit 14 is connected to the grout inlet pipe 17. The grout outlet on one side of the end cap pipe 18 is connected to the desander 11. The liquid outlet of the desander 11 is connected to the grout inlet pipe 17. The first conduit 13 is also provided with an inner tube 20. The lower end of the inner tube 20 is close to the lower opening of the first conduit 13, and the other end passes through the top of the end cap 18 and is connected to the air pump 21.

[0047] In the preferred embodiment, the top of the first conduit 13 is connected to the first winch 15, and the top of the second conduit 14 is connected to the second winch 16.

[0048] In the preferred embodiment, the second winch 16 is a double-rope double-drive winch, and the two hoisting ropes of the second winch 16 are respectively hinged to the top two sides of the second guide tube 14; The different winding speeds of the dual-rope winch allow the lower end of the second guide tube 14 to swing.

[0049] In the preferred embodiment, the top of the first conduit 13 is also provided with a fixing seat 19. The fixing seat 19 includes a fixing plate 1901, which is set on the top of the end cap tube 18. The fixing plate 1901 has a conical through hole in the middle, through which the inner tube 20 passes. It is also provided with multiple conical arc plates 1902, which are spliced ​​around the outer surface of the inner tube 20 and fit against the outer surface of the inner tube 20. The outer surface of the multiple conical arc plates 1902 forms a cone structure, which is stuck on the conical through hole in the middle of the fixing plate 1901.

[0050] In the preferred embodiment, the tops of adjacent conical arc plates 1902 are connected by a synchronous plate 1903. The top of the conical arc plate 1902 is also provided with a limiting pin 1904. The synchronous plate 1903 is provided with an oblong hole. The limiting pin 1904 passes through the oblong hole, and the limiting plate at the upper end of the limiting pin 1904 abuts against the upper surface of the synchronous plate 1903.

[0051] S8. After the trenching construction is completed, the steel cage is hoisted into the trench. The first winch 15 is used to lower the first guide pipe 13. The lower end of the first guide pipe 13 is lowered to a position of 40-50cm from the bottom of the trench. The end cap pipe 18 of the tee is installed on the first guide pipe 13. The slurry outlet of the end cap pipe 18 is directly connected to the sand remover 11. Then, the first winch 15 is used to lower the second guide pipe 14. The lower end of the second guide pipe 14 is lowered to a position of 30-40cm from the bottom of the trough. The slurry inlet pipe 17 is installed on the second guide pipe 14. The slurry inlet pipe 17 is connected to the desander 11 through the pump body. Multiple tubes are joined together to form an inner tube 20. The inner tube 20 is set inside the first guide tube 13, with the lower end of the inner tube 20 close to the lower end of the first guide tube 13, and the upper end of the inner tube 20 is fixed by a fixing seat 19. The lowering depth of the inner tube 20 is adjusted according to the cleaning time. The air pump 21 injects high-pressure air into the first conduit 13. Under the action of high air pressure, the mud between the inner pipe 20 and the first conduit 13 forms a circulation, and the bottom sediment of the tank is discharged through the slag discharge pipe along the gap between the inner pipe and the casting conduit. The sludge discharged through the sludge discharge pipe can be either directly discharged into the sedimentation tank for sedimentation or enter the mud desanding machine 11. After being purified by the mud, the solid waste is directly transported away, and the mud flow is transported back to the tank through the high-pressure jet pump to the slurry inlet pipe 17 for reuse. The winding reel at one end of the second winch 16 is fixed, while the winding reel at the other end is first lifted and then lowered, causing the second guide pipe 14 to start swinging inside the trough. The second guide pipe 14 agitates a large amount of sediment, and most of the agitated sediment is discharged from the first guide pipe 13. During the cleaning process, as the sediment at the bottom of the hole decreases, the first guide pipe 13 and the second guide pipe 14 are promptly lowered and poured. During the slag removal process, mud is promptly added to the hole. During the adjustment of the inner tube 20, the inner tube 20 is locked in place by the cooperation of the conical arc plate 1902 and the conical through hole on the fixed plate 1901, allowing for adjustment of the position and depth of the inner tube 20. In the construction of the ultra-long trench section, to address the problem of excessive sediment thickness, this project compiled hydraulic and sediment data from a near-balanced scour-siltation flood. Through analysis of the correlation between five sediment-carrying force influencing factors—sediment-carrying force criterion, relative viscosity coefficient of turbid water, resistance coefficient of turbid water, reciprocal of the effective unit weight of sediment in turbid water, and Karman constant of turbid water—a mathematical model was established. A method was proposed to directly substitute the average settling velocity of the turbid water and combine it with a fitting formula based on the relative viscosity coefficient of the turbid water for sediment-carrying force calculation, thereby optimizing the calculation equation for the total sediment-carrying force of suspended sediment.

[0052] The inner tube of the reverse circulation cleaning device is manufactured in sections, which facilitates its lowering and extraction. The separately manufactured inner tubes can be lowered to different lengths according to different trench depths, adapting to secondary cleaning of trench sections with different depths; By designing a pulsed positive circulation system, the filtered sand and gravel slurry can be directly introduced to the bottom of the tank through a conduit. Transforming the slurry from a continuous flow to a pulsed flow significantly improves fluid momentum. Furthermore, the pulsed airflow alleviates the desorption of microbubbles from the sediment surface and mitigates the longitudinal coalescence of microbubbles caused by the wake effect under continuous airflow. The pulsed positive circulation enhances the slurry bubble stability and works well with the air-lift reverse circulation, achieving a highly efficient sludge removal effect through the combined "air-lift reverse circulation + pulsed positive circulation" approach. This reduces orifice cleaning time, increases labor productivity, accelerates equipment turnaround time, and directly lowers engineering construction costs.

[0053] The above embodiments are merely preferred technical solutions of the present invention and should not be considered as limitations on the present invention. The scope of protection of the present invention should be limited to the technical solutions described in the claims, including equivalent substitutions of the technical features described in the claims. That is, equivalent substitutions and improvements within this scope are also within the scope of protection of the present invention.

Claims

1. A trenching construction system for ultra-deep diaphragm wall ultra-long trench sections, characterized by: The system includes a mud recycling system, which includes a desander (12). The desander (12) is connected to the internal lifting pump of the hydraulic milling machine (1). The outlet of the desander (12) is connected to multiple desanders (11). The slag outlets of the desander (12) and the desanders (11) are connected to the slag collection pit (3). The outlet of the desanders (11) is connected to the purification station storage tank (4). The purification station storage tank (4) is cleaned by a centrifugal filter (6). The purification station storage tank (4) is connected to the tank through the first pump body (2). The construction system also includes a secondary hole cleaning system: including at least two guide pipes, one end of which is set in the trench and the other end is connected to the lifting device. The top of the first guide pipe (13) is connected to the end cap pipe (18) of the three-way structure, and the upper end of the second guide pipe (14) is connected to the slurry inlet pipe (17). The slurry outlet on one side of the end cap pipe (18) is connected to the sand remover (11), and the liquid outlet of the sand remover (11) is connected to the slurry inlet pipe (17). The first conduit (13) is also provided with an inner tube (20). The lower end of the inner tube (20) is close to the lower opening of the first conduit (13), and the other end passes through the top of the end cap (18) and is connected to the air pump (21). The first conduit (13) is also provided with a fixing seat (19) at the top. The fixing seat (19) includes a fixing plate (1901). The fixing plate (1901) is set at the top of the end cap tube (18). The fixing plate (1901) has a conical through hole in the middle. The inner tube (20) passes through the conical through hole. It is also provided with multiple conical arc plates (1902). The multiple conical arc plates (1902) are spliced ​​around the outer surface of the inner tube (20) and fit against the outer surface of the inner tube (20). The outer surface of the multiple conical arc plates (1902) forms a vertebral structure. The vertebral structure is stuck on the conical through hole in the middle of the fixing plate (1901). The tops of adjacent conical arc plates (1902) are connected by a synchronous plate (1903). The top of the conical arc plate (1902) is also provided with a limiting pin (1904). The synchronous plate (1903) is provided with an oblong hole. The limiting pin (1904) passes through the oblong hole, and the limiting plate at the upper end of the limiting pin (1904) abuts against the upper surface of the synchronous plate (1903). The top of the first conduit (13) is connected to the first winch (15), and the top of the second conduit (14) is connected to the second winch (16); The second winch (16) is a double-rope double-drive winch. The two ropes of the second winch (16) are respectively hinged to the top two sides of the second guide tube (14). The different winding speeds of the double-rope winch cause the lower end of the second guide tube (14) to swing.

2. The trenching construction system for ultra-deep diaphragm wall ultra-long trench sections according to claim 1, characterized in that: The inlet of the centrifugal filter (6) is connected to the purification station storage tank (4) through the second pump body (5), and the outlet of the centrifugal filter (6) is connected to the purification station storage tank (4).

3. The trenching construction system for ultra-deep diaphragm wall ultra-long trench sections according to claim 1, characterized in that: The mud raw material warehouse (10) is connected to the mud storage tank (8) through the mud preparation station (9), and the mud storage tank (8) is connected to the purification station storage tank (4) through the third pump body (7).

4. The trenching construction system for ultra-deep diaphragm wall ultra-long trench sections according to claim 3, characterized in that: The mud storage tank (8) is composed of multiple tanks stacked together, with the tanks getting smaller from bottom to top.

5. The trenching construction system for ultra-deep diaphragm wall ultra-long trench sections according to any one of claims 1-4, characterized in that: Trenching construction methods include: S1. Use plaxis 3d software to model the geological conditions of the entire trenching location. Based on the specific gravity of the mud, simulate the stability changes of the trench wall under actual working conditions at the trenching location. Set the positions of the milling machine and the crane. Use plaxis 3d software to analyze the deformation and settlement of the trench. Observe the deformation cloud map of the milled trench wall during the trenching construction. S2. Based on the analysis of the above-mentioned Plaxis 3D software, the specific gravity and viscosity of the mud are obtained, and composite standard mud is prepared. S3. The raw materials inside the mud raw material warehouse (10) are mixed by the pulping station (9) and then transported to the mud storage tank (8). The mud storage tank (8) is transported to the purification station storage tank (4) by the third pump (7). The purification station storage tank (4) is transported to the tank through the first pump (2). S4. The drilling mud in the slot is pumped to the desander (12) by the mud pump in the milling head. The drill cuttings larger than 5mm in the mud are screened out by the vibrating coarse screen. The treated mud is then transported to the desander (11) to separate the fine sand larger than 0.06mm in the mud. The screened sand is transported to the slag collection pit (3) by the conveyor belt. The mud after secondary treatment is transported to the purification station storage tank (4) for storage. S5. The slurry inside the purification station storage tank (4) is treated by a horizontal screw discharge sedimentation centrifugal filter (6). The centrifugal force is used to separate fine particles larger than 0.03mm in the slurry. After treatment, the slurry is returned to the tank hole. S6. Use hydraulic milling (1) and hydraulic grab bucket to form a groove by combining grab milling. The upper grab bucket forms a groove to the soft soil layer, and the lower part is milled into a groove. After entering the hard soil layer, use hydraulic milling machine to mill until the end hole. Then use mud circulation to clean the hole. After the groove is completed and accepted, use hydraulic milling and mud purification system to clean the hole and change the mud. S7. The hydraulic grab bucket is used to grab the soil on both sides of the trench section divided at the construction location in the following steps: grab the soil in the center first. A soil layer is left between the trench holes after each grab. The trench is measured with an ultrasonic inclinometer to observe the integrity of the trench. Fresh mud should be continuously injected into the trench during the trenching process. S8. After the trenching construction is completed, the steel cage is hoisted into the trench. The first guide pipe (13) is lowered first using the first winch (15). The lower end of the first guide pipe (13) is lowered to a position of 40-50cm from the bottom of the trench. The end cap pipe (18) of the three-way connector is installed on the first guide pipe (13). The slurry outlet of the end cap pipe (18) is directly connected to the sand remover (11). Then, the second guide pipe (14) is lowered using the first winch (15). The lower end of the second guide pipe (14) is lowered to a position 30-40cm below the bottom of the tank. The slurry inlet pipe (17) is installed on the second guide pipe (14). The slurry inlet pipe (17) is connected to the sand remover (11) through the pump body. Multiple tubes are connected to form an inner tube (20). The inner tube (20) is set inside the first conduit (13), and the lower end of the inner tube (20) is close to the lower end of the first conduit (13). The upper end of the inner tube (20) is fixed by a fixing seat (19). The lowering depth of the inner tube (20) is adjusted according to the cleaning time. S9. The air pump (21) injects high-pressure air into the first conduit (13). Under the action of high air pressure, the mud between the inner pipe (20) and the first conduit (13) forms a circulation, and the bottom sediment of the tank is discharged through the slag discharge pipe along the gap between the inner pipe and the casting conduit. The sludge discharged through the sludge discharge pipe can be either directly discharged into the sedimentation tank for sedimentation or sent to the mud desander (11). After being purified by the mud, the solid waste is directly transported away, and the mud flow is transported to the slurry inlet pipe (17) by the high-pressure jet pump and returned to the inside of the tank for reuse. S10. Control the winding reel at one end of the second winch (16) to be fixed, and the winding reel at the other end to be lifted and then lowered, so that the second guide pipe (14) starts to swing inside the trough. The second guide pipe (14) stirs up a large amount of sediment, and most of the stirred sediment is discharged from the first guide pipe (13). S11. During the cleaning process, as the sediment at the bottom of the hole decreases, the first guide pipe (13) and the second guide pipe (14) are lowered and poured in a timely manner. During the slag removal process, mud is added to the hole in a timely manner. S12. During the adjustment of the inner tube (20), the inner tube (20) is locked in place by the cooperation of the tapered arc plate (1902) and the tapered through hole on the fixed plate (1901), and the position and depth of the inner tube (20) can be adjusted.

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