Technology Innovation In Dredge

Technology Innovation In Dredge

1. Overview of channel dredging by cutter suction dredger

1.1 Construction principle of cutter suction dredger

When the cutter suction dredger is operating, it uses steel pillars for positioning, and determines the width of the trench according to the requirements of the dredging operation. The cutter suction dredger is a static operation. The sludge is excavated with the help of the cutter head. The soil is cut into powder and sucked into the ship for transportation by the suction dredger. It can realize the integrated operation of excavation, transportation and dumping, effectively improving work efficiency and reducing construction costs.

1.2 Construction technology of cutter suction dredger

In the dredging construction process of the cutter suction vessel channel, the stepping and transverse digging method is mainly used for construction. The construction personnel analyze the scope of channel dredging, and carry out construction operations in a layered and segmented manner:

  • 1.2.1 The construction personnel must place the dredger at the designated location.
  • 1.2.2 Use GPS positioning technology to determine the location of the starting point of the trench, and perform excavation operations after determining the location.
  • 1.2.3 When the trench excavation is completed, the mud pipeline needs to be placed. Finally, determine the position of the reamer, and follow the design position below the reamer. During the construction process, the construction personnel need to strictly control the position of the dredger. The specific operation steps are as follows:
    • 1) Layered construction. For areas with thick mud layers in the trenches, one-time excavation cannot meet the design requirements, and layered excavation can be selected for operation. When determining the layer thickness, the construction personnel must pay close attention to the working conditions of the ship’s equipment and conduct strict demonstration tests to ensure that it meets the construction requirements.
    • 2) Split construction. The construction plan is selected according to the width of the trench design, and the subdivision construction method is adopted for the dredging of the channel with a large trench width. When dredging the river section with silt and sand, the construction personnel need to analyze and investigate the density and viscosity of the channel sand during the subsection construction, and increase or decrease the width of the trench according to the actual channel conditions. For the river course where the clay is stored, the construction personnel need to analyze the softness and hardness of the river clay and make appropriate adjustments.
    • 3) Construction in sections. When the channel is being dredged, because the digging groove is bent or the digging groove is too long to reach the design goal, it is necessary to use the segmented construction method to operate. In addition, it is necessary to determine the best radius of curvature according to the heading angle of the cutter suction dredger.

1.3 Key links and control of channel dredging

In the side anchor setting operation, when the construction personnel use the cutter suction dredger to work, they need to ensure that the two sides of the bow and the center line are kept at an angle of 75°, and the anchor position must be kept at a certain distance from the trench boundary line. The side anchor is dropped every time the suction dredger moves. In order to effectively improve the efficiency of side anchor setting, the construction personnel need to use the anchor boat to carry out the operation when performing the setting operation. Use GPS positioning technology to determine the position of the side anchors, and set signs on the anchors to ensure the safety of the operation. When arranging the mud pipeline, the construction personnel shall determine the length of the pipeline and the movement path of the pipeline based on the water flow speed and direction of the work area. The pipeline and other materials shall not occupy the normal channel.

2. Technical transformation to improve the dredging capacity of cutter suction dredgers

The traditional cutter suction dredger is mainly composed of the following major systems

  • 1. It is a cutting system, consisting of a reamer, a reamer bridge and a landing gear, etc.
  • 2. It is a conveying system, which is composed of a mud pump, a suction port, a mud discharge pipeline, etc.
  • 3. It is a shifting system, consisting of a traverse winch, positioning piles and their landing gear, etc.
  • 4. It is a power control and auxiliary system, which consists of the main engine, auxiliary engines, various instruments, control valves, etc.

These systems are complementary to each other, form a whole, and show different constraints due to different working conditions, but in terms of improving dredging efficiency without increasing the driving force, the focus is on improving cutting, conveying, displacement and operation auxiliary system.

1. Technology innovation in dredge about cutting system

The twisting force is the cutting tool of the cutter suction dredger to cut underwater soil. It is driven by the prime mover to rotate and cut the soil layer, and the soil layer separated by the cutting is deformed and broken and mixed with water to form a slurry that is fed by the suction port in the cutter cavity People mud pump.

In order to improve the cutting ability of the reamer, people have designed various types of reamers, such as open reamer, closed reamer, and tooth reamer, according to different working conditions and soil types. However, no matter what kind of reamer, there are “straight knife” and “reverse knife” in the cutting process.

When the transverse direction of the reamer bridge is consistent with the rotation direction of the reamer, it is called “positive knife” cutting. At this time, the resistance of the reamer to overcome the cutting soil comes from the self-weight pressure of the reamer and its bridge frame. Under normal circumstances, when the cutting soil is relatively soft, whether it is “left rotation” or “right rotation”, the reamer can cut normally;

However, when the soil to be cut is relatively hard, or the resistance of the soil layer against the cutting of the reamer is greater than the weight pressure of the reamer bridge, the “hob” phenomenon will appear, which makes the cutting of the reamer more difficult.

In order to solve the low efficiency of cutting hard soil by the reamer, a bucket wheel reamer was designed. This is a kind of technology innovation in dredge. The biggest difference between the bucket wheel reamer and the ordinary reamer is that the rotation line and the axis of the bridge are not coaxial but intersecting. 90°.

It is this point that makes the bucket wheel reamer move to the left or right during the cutting process, its cutting shape is similar to the “back knife” in the ordinary reamer cutting process, which effectively solves the problem of soil during the cutting process. The “hob” problem when the resistance is greater than the deadweight pressure of the reamer bridge frame, greatly improves the efficiency of cutting hard soil. It is precisely because the shallow reamer has the advantage of digging hard soil, so if the existing equipment of the company is a cutter suction dredger, and often encounters similar plastic clay or hard clay working conditions, there should be a choice Renovation of bucket-wheel cutters is carried out locally, and the cutter-suction dredger is transformed into a bucket-wheel dredger or a bucket-wheel cutter-suction dredger.

2. Conveyor system – technology innovation in dredge about mud pump

The mud pump is a key component for the dredger to transport the cut mud water mixture to the designated storage yard. The performance of the mud pump and the flow rate directly affect the dredging efficiency. Generally speaking, the larger the flow rate and the higher the head of the mud pump, the stronger the ability to transport the mud, the longer the transport distance, and of course the greater the shaft power required.

According to this basic relationship of the dredge pump, Leader Dredger modified the dredge pump system of the hydraulic cutter suction dredger. The host only loads the hydraulic system of the mud pump. The power generation system is loaded by another auxiliary machine, so the power of the main machine is relatively rich. For this reason, we have increased the maximum discharge distance of the mud pump without changing the main engine.

3. Technology innovation in dredge about mobile systems

The cutter suction dredger cuts the soil layer with the positioning pile on one side as the center of rotation, and relies on the left and right laterally moving winches to pull the swing cables on both sides, so that the cutter head swings left and right, and the cutting is layered from top to bottom. to make. When the cutting of the soil in a section is completed, the cutter head will move forward a certain distance. This forward movement requires two piles to rise and fall alternately and coordinate with the swing of the hull to complete. Each time the cutter head moves forward, the main and auxiliary piles must be raised and lowered twice. In this process, the mud pump only pumps clean water and does not discharge mud, so the dredging efficiency is greatly affected. In response to the disadvantages of the displacement of fixed positioning piles, Leader Dredger designed a trolley-type positioning pile.

The trolley-type positioning pile relies on the push of the oil cylinder to realize the forward movement of the reamer. Within one stroke of the oil cylinder, the reamer can be moved forward multiple times. When the main pile moves to the maximum position, the auxiliary pile is dropped and the main pile is lifted. Under the contraction of the oil cylinder of the trolley, move to the designated point, drop the main pile, lift the auxiliary pile, and complete a pile replacement process. Trolley-type positioning piles are easy to operate and move accurately. Within the same forward movement distance, the number of pile replacements is greatly reduced, thus reducing the time for the mud pump to pump clean water. According to calculations, the use of trolley-type positioning piles can improve work efficiency by more than 20% compared with fixed positioning piles. Two forms can be used to transform the fixed positioning pile into a trolley type positioning pile

  • One is to remove all the upper and lower hoops of the original fixed positioning pile, remake the welding trolley track on the dredger ship plate and connect it with the original longitudinal keel and rib of the ship to form a “Y” body. Re-determine the position of the mobile main pile and the fixed auxiliary pile.

  • Another form is to retain the original fixed positioning pile hoop, remake the independent part, design the trolley, track and fixed auxiliary pile on the part, and make the connecting clamp at the appropriate position on the front side of the boat, and then The newly made ship clamp is connected with the hoop of the original fixed positioning pile to form a relatively independent detachable trolley-type positioning pile with the original ship. No matter which form is adopted, the original pile and lifting device can be used, as long as a mobile cylinder is added and the corresponding steel structure reform is done. The cost is more economical and ordinary enterprises can afford it, but the benefits after the transformation will be greatly improved.

4. Technology innovation in dredge about auxiliary operating system

During the construction of a cutter suction dredger, the operator usually cannot visually detect the mud outlet concentration of the mud pipe. Generally, they can only control the mud concentration by adjusting the feed depth and swing speed based on the readings of the vacuum gauge and pressure gauge.

However, this kind of operation method is firstly dependent on the operator’s experience and sense of responsibility, and secondly, it is difficult to adjust the excavation parameters in a timely manner due to the influence of various variables such as water flow, soil quality, terrain, and obstacles during the operation. To achieve the best condition, the dredging concentration of different operators and different time periods is very large, which seriously affects the efficiency of the equipment.

In order to effectively solve this problem, Leader Dredger installed a production meter on the dredger. Traditional output meters are designed using the principle of radioactive drills or brilliant radioactive sources, but this type of output meters has radioactive pollution, and at the same time it is troublesome to adjust and maintain, and has low reliability.

At present, the electromechanical intelligent integrated production meter designed by the method of continuous dynamic weighing of fluid and ultrasonic Doppler velocity measurement can display not only the concentration and flow rate, but also the flow, pipe pressure, density, specific gravity, yield, etc., and it can be stored for a long time. Randomly print parameters such as operator number, shift output, total cumulative output, start-up time and effective working time

3. Concluding remarks on technology innovation in dredge

With the deepening of ecological balance and environmental protection awareness, people will pay more and more attention to the comprehensive management of the water environment, which also provides an unprecedented development opportunity for the dredging industry.

While we are actively introducing new types of dredging equipment and popularizing new technologies and techniques for dredging, we should increase efforts to update and transform traditional dredging equipment according to local conditions and needs.

In addition to the transformation of components such as the reamer, mud pump, trolley, and output meter, according to the working conditions and economic strength, the cutter head suitable for extra-hard soil can be selectively carried out, suitable for open Anchor rods for water area construction, GPS positioning, water level remote reporting and depth sounding system transformation suitable for ecological cleanliness and precise dredging.

Through technological transformation, the dredger can realize its potential and improve work efficiency. This will not only create better economic benefits for the unit, but also greatly improve the dredging capacity of the dredger for the Jianghe Lake Reservoir.