A method for calculating the rake head dredging yield of a trailing suction dredger

Abstract

The application discloses a kind of draghead excavating production calculation method of drag suction dredger, the excavating production is related to total breaking depth, draghead width and draghead advancing speed, the total breaking depth includes drag tooth breaking depth, jet breaking depth, the relationship between drag tooth operating parameter and drag tooth breaking depth is obtained by experiment respectively, and the relationship between jet operating parameter and jet breaking depth, and based on this, establish draghead excavating production calculation model, to obtain the calculation result of draghead excavating production.The method can quantitatively know the influence effect of these operating parameters on production, and also provide important theoretical reference for the design, research and manufacture of draghead, which is the theoretical basis for improving the performance of draghead equipment and solving practical construction problems, and is helpful for the high-quality development of dredging vessels.Moreover, the method has been tested on a real ship, and the calculated production value is consistent with the production value directly measured by the sensor, verifying the feasibility and accuracy of the method.

Description

Technical Field

[0001] This invention belongs to the field of dredging engineering technology, specifically relating to a method for calculating the dredging output of a trailing suction dredger. Background Technology

[0002] A trailing suction hopper dredger mainly consists of a dredger head, dredger arms, a mud pump, and a mud hopper. During operation, the dredger first lowers the dredger arms, bringing the dredger head into contact with the underwater mud surface. The dredger head, through hydraulic cylinders and its own weight, presses its teeth into the mud. The forward movement of the dredger propels the dredger head to excavate. The excavated soil is then pumped through the dredger arms into the mud hopper by the mud pump. Once the hopper is full, the dredger dumps and backfills the mud. The dredger head, as the primary excavating equipment, directly affects the dredger's operational efficiency.

[0003] In actual construction, the output of the rake head is often obtained by monitoring the flow rate and concentration in the pipeline. However, this is only the result of the rake head operation. In order to optimize the output of the rake head by adjusting the operating parameters and to achieve intelligent rake head operation, it is necessary to understand the relationship between the operating parameters and the output. However, the complex structure of the rake head and the large number of operating parameters make it difficult to solve this problem.

[0004] With the development of big data technology, some researchers have applied it to this problem. Through a large amount of engineering measurement data, they have established the relationship between operating parameters and the output of the dredger. However, this method is limited by the accuracy and range of engineering data. In particular, once the parameters exceed the range of measured data, the prediction accuracy of this method is greatly reduced (e.g., Pan Zhiwei, Research on the Excavation and Slurry Transportation Mechanism of Trailing Suction Hopper Dredger Based on Artificial Intelligence, Master's Thesis, Jiangsu University of Science and Technology, 2019).

[0005] Some researchers have also developed a model for calculating digging depth by analyzing the forces acting on the rake head and combining the cutting mechanism of the blades with the jet mechanism. However, this model is complex and has poor applicability (Kyle de Jonge, A trailing suction hopper dredgedraghead production model, MsD, Delft University of Technology, 2017).

[0006] Therefore, it is necessary to establish a practical and relatively simple model for calculating the output of rake digging. Summary of the Invention

[0007] The purpose of this invention is to improve upon the aforementioned shortcomings and deficiencies of the existing technology, thereby providing a novel method for calculating the dredging output of a trailing suction hopper dredger.

[0008] To achieve the above objectives, the present invention adopts the following technical solution:

[0009] This invention provides a method for calculating the dredging output of a trailing suction dredger. The dredging output is related to the total breaking depth, the width of the trailing suction dredger, and the forward speed of the trailing suction dredger. The total breaking depth includes the breaking depth of the trailing suction dredger teeth and the breaking depth of the jet. The relationship between the operating parameters of the trailing suction dredger teeth and the breaking depth of the trailing suction dredger teeth, as well as the relationship between the operating parameters of the jet and the breaking depth of the jet, are obtained through experiments. Based on this, a model for calculating the dredging output of the trailing suction dredger is established to obtain the calculation result of the dredging output of the trailing suction dredger.

[0010] Furthermore, the method for calculating the dredging output of the trailing suction hopper dredger includes the following steps:

[0011] S1: Calculation of the depth of the rake teeth breaking through the soil

[0012] S1-1: Obtain the rake head gravity G 耙头 (N), Rake tooth type n 耙齿 The four parameters are: the number of rake teeth, and the angle at which the rake teeth enter the soil, α (°).

[0013] S1-2: Calculate the soil breaking depth H of the rake teeth 齿 (cm):

[0014] Rake tooth penetration force F 贯入 (N) represents the ground reaction force on the rake teeth. For any rake head and rake arm system with a defined structure and arrangement, the rake tooth penetration force F is... 贯入 With the gravity G of the rake head 耙头 The following relationship exists:

[0015] F 贯入 =k 贯入 ·G 耙头 (1);

[0016] In equation (1), k 贯入 This is the penetration force coefficient;

[0017] H, the depth of the rake teeth breaking the soil 齿 (cm) and the soil penetration angle α (°) of the rake teeth, and the penetration force F of the rake teeth 贯入 (N) and the number of rake teeth n 耙齿 The relationship is as follows:

[0018]

[0019] In equation (2), the parameters k1 and k2 are obtained through experiments;

[0020] S2: Calculation of jet penetration depth

[0021] S2-1: Obtain the jet flow rate Q(m 3 / h), nozzle diameter D (cm), nozzle moving speed V (m / s), i.e., the rake head forward speed, and soil strength S u (kPa) four parameters;

[0022] S2-2: Calculate the depth of jet penetration H 射流 (cm)

[0023] Jet penetration depth H 射流 (cm) and nozzle diameter D (cm), jet flow rate Q (m³) 3 / h), nozzle moving speed V (m / s), and shear strength S u The relationship between (kPa) is as follows:

[0024]

[0025] In equation (3), a and b are fitting parameters, which are determined through experiments;

[0026] S3: Calculation of Total Breakthrough Depth

[0027] Breakthrough depth H 总 (m) is:

[0028] H 总 =(H 齿 +H 射流 )*0.01 (4)

[0029] S4: Calculation of Total Excavation Volume of the Harrow Head

[0030] Total excavation volume P of the rake 耙头总挖掘量 (m 3 / h) and total breaking depth H 总 The relationship between the rake head width W (m) and the rake head forward speed V (m / s) is as follows:

[0031] P 耙头总挖掘量 =3600 W H 总 ·V (5);

[0032] S5: Calculation of Total Rake Output

[0033] Total output of rake heads P 耙头总产量 (m 3 / h) Calculated according to the following formula:

[0034] P 耙头总产量 =k 吸入 ·P 耙头总挖掘量 (6)

[0035] In equation (6), k 吸入 The harrow head suction coefficient is defined as the ratio of the total output of the harrow head to the total digging volume of the harrow head. The value of the harrow head suction coefficient can be determined through physical experiments.

[0036] Furthermore, the k 贯入 The value ranges from 0.3 to 0.8.

[0037] Furthermore, k1 and k2 differ for different rake tooth types and soil types. For silty soil, the values ​​are shown in the table below:

[0038] Narrow teeth Wide teeth <![CDATA[k1]]> -7.5 -4 <![CDATA[k2]]> 810 591.33 .

[0039] The beneficial effects of the method for calculating the output of the trailing suction hopper dredger head in this invention are as follows:

[0040] (1) This invention analyzes the composition of the rake head output from a mechanistic perspective and obtains a quantitative relationship between operating parameters and output through experiments, establishing a semi-empirical calculation formula to obtain the final output of the suction pipe. If the output obtained by directly measuring the concentration meter and flow meter on the pipe is the "effect," then the rake head output obtained by this method is the "cause." The former can only obtain the output value, which is relatively accurate, but it can only qualitatively know that the operating parameters have an impact on the output, and the specific impact law is not clear; while the latter can quantitatively know the effect of these operating parameters on the output, which can provide an important theoretical reference for the design, research and manufacturing of rake heads, and is also the theoretical basis for improving the performance of rake head equipment and solving practical construction problems, which is conducive to the high-quality development of dredging vessels.

[0041] (2) The method was tested on a trailing suction hopper dredger. The calculated output value was in good agreement with the output value directly measured by the sensor, which verified the feasibility and accuracy of the method. Attached Figure Description

[0042] Figure 1 This is a flowchart illustrating the method for calculating the dredging output of the trailing suction hopper dredger according to the present invention.

[0043] Figure 2 This is an experimental result diagram of a high-pressure jet soil breaking test.

[0044] Figure 3 The depth of the jet penetration is H. 射流 The relationship between jet flow rate Q and nozzle moving speed V.

[0045] Figure 4 This is a comparison of predicted output and actual output. Detailed Implementation

[0046] The technical solution of the present invention will be clearly and completely described below with reference to the accompanying drawings and specific embodiments. It should be understood that the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of the present invention.

[0047] Example 1: Calculation Method for Drilling Output of Trailing Suction Hopper Dredger

[0048] Combination Figure 1 The flowchart shown below illustrates the specific calculation method for the dredging output of a trailing suction hopper dredger:

[0049] S1: Calculation of the depth of the rake teeth breaking through the soil

[0050] S1-1: Obtain the rake head gravity G 耙头 (N), type of rake teeth, number of rake teeth n 耙齿 The four parameters are: the angle of the rake teeth into the soil, α (°);

[0051] S1-2: Calculate the soil breaking depth H of the rake teeth 齿 (cm);

[0052] Rake tooth penetration force F 贯入 The ground reaction force on the rake teeth, for any rake head and rake arm system with a fixed structure and layout, when the construction operation parameters do not change significantly, is the rake tooth penetration force F. 贯入 With the gravity G of the rake head 耙头 The following relationship exists:

[0053] F 贯入 =k 贯入 ·G 耙头 (1);

[0054] In equation (1), k 贯入 To determine the penetration force coefficient k, multiple sets of tests were conducted. 贯入 The value range is generally between 0.3 and 0.8.

[0055] Penetration depth tests were conducted on two commonly used prototype rake teeth (wide and narrow teeth) in silty sand, as detailed below:

[0056] Individual rake teeth are mounted on a raised and lowerable test bench equipped with force sensors to measure the forces acting on the teeth. The rake tooth entry angle is set, the test bench is lowered to press the tooth into the soil, and the resistance experienced by the tooth is measured in real time. Then, the test bench is raised to lift the tooth out of the soil, and the actual final penetration depth is measured. This process is repeated multiple times, with the penetration depth increasing each time. The rake tooth penetration angle is changed, and the penetration process is repeated. The average resistance required for a single rake tooth to penetrate a unit depth is calculated for different penetration angles.

[0057] Linear fitting was performed on the experimental data, and considering that the rake head has multiple teeth, the soil breaking depth H of the rake teeth was obtained. 齿 (cm) and the soil penetration angle α (°) of the rake teeth, and the penetration force F of the rake teeth 贯入 (N) and the number of rake teeth n 耙齿 The relationship is as follows:

[0058]

[0059] In equation (2), parameters k1 and k2 are obtained through experiments. For different types of rake teeth and soil types, k1 and k2 are different. In this embodiment, silty sand is used as an example, and the values ​​are shown in Table 1 below.

[0060] Table 1. Values ​​of parameters k1 and k2 for different tooth profiles.

[0061] Narrow teeth Wide teeth <![CDATA[k1]]> -7.5 -4 <![CDATA[k2]]> 810 591.33

[0062] S2: Calculation of jet penetration depth

[0063] S2-1: Obtain the jet flow rate Q(m 3 / h), nozzle diameter D (cm), nozzle moving speed V (m / s) (i.e., rake head forward speed), and soil strength S u (kPa) four parameters;

[0064] S2-2: Calculate the depth of jet penetration H 射流 (cm);

[0065] High-pressure jet penetration tests were conducted to calculate the jet penetration depth. The high-pressure water jet performance test was performed in a glass water tank measuring 13m long, 0.8m wide, and 1.1m high. A dredging tank was parallel to the glass water tank. A test trolley located at the top of the dredging tank traveled along a track, and its speed could be set via a frequency converter according to test requirements. The water supply pipeline for the high-pressure water jet device on the test trolley was fixed to the water tank via a frame, with one end of the pipeline connected to… The pressure-resistant hose is connected to the high-pressure water pump, and the other end is connected to the high-pressure water nozzle through a flange.

[0066] This experiment used silty sand as the research object. To ensure similar soil conditions in the experiments, the soil was leveled, compacted, and then soaked in water before each test. The aim was to ensure both the density of the soil and that it was saturated during the experiment. The experiment was conducted using a high-pressure water jet nozzle perpendicular to and in close contact with the mud surface. The flow rate of the high-pressure water pump was controlled by adjusting the pump speed.

[0067] To compare the effects of high-pressure water jet flow rate and nozzle movement speed on the rinsing effect, experiments were conducted on three combinations of jet flow rate and three nozzle movement speeds. The experimental results are as follows: Figure 2 As shown, the experimental conditions are as follows, where n is the speed of the high-pressure water pump:

[0068] ① Tank: V = 0.3 m / s, Q = 28 m 3 / h, n=1500rpm ② Tank: V=0.5m / s, Q=28m 3 / h, n=1500rpm

[0069] ③ Tank: V = 0.8 m / s, Q = 28 m 3 / h, n=1500rpm ④ Tank: V=0.8m / s, Q=26m 3 / h, n=1200rpm

[0070] ⑤ Channel: V = 0.8 m / s, Q = 18 m 3 / h, n=900rpm

[0071] The experimental results show that, comparing tanks ①, ②, and ③, under the same jet flow rate, the lower the nozzle moving speed, the greater the depth and width of the high-pressure water flushing tank; comparing tanks ③, ④, and ⑤, under the same nozzle moving speed, the greater the jet flow rate, the greater the depth and width of the high-pressure water flushing tank. It is known that the nozzle moving speed is inversely proportional to the high-pressure water action time per unit area, and the flow rate is directly proportional to the jet velocity (the square of the dynamic pressure). Therefore, reducing the nozzle moving speed and increasing the flow rate are both beneficial for flushing.

[0072] The experimental results were fitted to the data, and the results are as follows: Figure 3 As shown, the depth of the jet penetration H 射流 (cm) and nozzle diameter D (cm), jet flow rate Q (m³) 3 / h), nozzle moving speed V (m / s), and soil strength S u The relationship between (kPa) is as follows:

[0073]

[0074] In equation (3): where a and b are fitting parameters, S u The soil strength (kPa) was determined experimentally. In this embodiment, the fitting parameters a and b were 0.174 and 0.6135, respectively. The strength S of the silty sand soil used was... u =32kPa.

[0075] S3: Calculation of Total Breakthrough Depth

[0076] Total breaking depth H 总 (m) is:

[0077] H 总 =(H 齿 +H 射流 )*0.01 (4)

[0078] S4: Calculation of Total Excavation Volume of the Harrow Head

[0079] Total excavation volume P of the rake 耙头总挖掘量 (m 3 / h) In addition to the total breaking depth H 总 In addition to the above, it is also related to the width W (m) of the rake head and the forward speed V (m / s) of the rake head, as detailed below:

[0080] P 耙头总挖掘量 =3600 W H 总 ·V (5);

[0081] S5: Calculation of Total Rake Output

[0082] Total output of rake heads P 耙头总产量 (m 3 / h) Calculated according to the following formula:

[0083] P 耙头总产量 =k 吸入 ·P 耙头总挖掘量 (6).

[0084] The soil excavated by the harrow cannot be completely sucked in by the harrow, resulting in some loss. Therefore, the ratio of the total harrow output to the total excavation volume is defined as the harrow suction coefficient k. 吸入 The inhalation coefficient can be determined through physical experiments, with a maximum value not exceeding 1, and is generally taken as 0.9 in engineering.

[0085] The calculation of the dragline suction dredger's head output in Example 1 above was conducted for a domestic waterway dredging project. The soil quality was sourced from the project site, and the dragline teeth were derived from the test vessel. Therefore, the empirical formula obtained can directly calculate the actual ship output, i.e., the predicted output. The actual output sucked in by the dragline head can be directly obtained using onboard concentration meters and flow meters, i.e., the measured output. The comparison results between the predicted output and the measured output are as follows: Figure 4 As shown.

[0086] Figure 4The horizontal axis represents the measured output. Due to the influence of wind, waves, currents, and seabed topography during actual dredging operations, the actual output varies even under the same operating parameters. Therefore, the rake head dredging data is sorted and grouped according to rake head forward speed, rake tooth insertion angle, jet flow rate, and output, and then the average value is taken as the actual dredging output (for specific processing methods, refer to CN113483805A "A Data Processing Method for Long-Distance Pipeline Dredging and Conveying System"). The vertical axis represents the predicted output calculated using the above model. The closer the scatter points in the graph are to the central straight line, the more accurate the representation. From... Figure 4 The comparison results show that this method has a certain degree of accuracy and can effectively obtain the rake head yield. It provides an important theoretical reference for rake head design, research, and manufacturing.

[0087] It is worth noting that the present invention provides a method for calculating the output of the scraper head of a scraper suction dredger. For different soil types and scraper heads, the correlation coefficients in the empirical formula need to be obtained through indoor tests. The coefficients in Example 1 are only applicable to the working conditions in Example 1.

[0088] The basic principles, main features, and advantages of the present invention have been described in detail above. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of the invention. Various changes and modifications can be made to the present invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the present invention as claimed.

Claims

1. A method of calculating a rake head dredging yield of a trailing suction hopper dredger, characterized in that, The excavation output is related to the total breaking depth, the width of the harrow head, and the forward speed of the harrow head. The total breaking depth includes the breaking depth of the harrow teeth and the breaking depth of the jet. The relationship between the harrow tooth operating parameters and the breaking depth of the harrow teeth, and the relationship between the jet operating parameters and the breaking depth of the jet, are obtained through experiments. Based on this, a harrow head excavation output calculation model is established to obtain the calculated results of the harrow head excavation output. The method for calculating the harrow head excavation output of the trailing suction hopper dredger includes the following steps: S1: Calculation of the depth of the rake teeth breaking through the soil S1-1: Obtain the gravity of the harrow head (N), harrow tooth type, harrow tooth number , and harrow tooth angle of entry into the soil α (°) S1-2: Calculate the tine penetration depth (cm): Rake tooth penetration force (N) represents the ground reaction force on the rake teeth. For any rake head and rake arm system with a defined structure and arrangement, the rake tooth penetration force is... With the gravity of the rake head The following relationship exists: （1）； In formula (1), is the penetration force coefficient; rake tooth breaking depth (cm) and the angle α (°) of the rake teeth into the soil, and the penetration force of the rake teeth (N) and number of rake teeth The relationship is as follows: （2）； In equation (2), the parameters k1 and k2 are obtained through experiments; S2: Calculation of jet penetration depth S2-1: Obtain the four parameters of jet flow Q (m 3 / h), nozzle diameter D (cm), nozzle moving speed V (m / s), i.e. the rake head advancing speed, and soil strength S u (kPa) S2-2: Calculate the jet breaking soil depth Jetting depth (cm) and the nozzle diameter D (cm), jet flow rate Q (m 3 / h), nozzle moving speed V (m / s), and shear strength S u (kPa) are as follows: （3）； In equation (3), a and b are fitting parameters, which are determined through experiments; S3: Calculation of Total Breakthrough Depth Depth of soil breaking (m) is: （4） S4: Calculation of Total Excavation Volume of the Harrow Head Total amount of digging by a tine (m 3 / h) and total depth of breaking (m), the tine width W (m), and the tine advance speed V (m / s) are as follows: （5）； S5: Calculation of Total Rake Output Total rake head production (m 3 / h) is calculated according to the formula: （6） In formula (6), The rake head suction coefficient can be determined by physical experiments.

2. The trailing suction hopper dredger bucket excavation yield calculation method according to claim 1, characterized in that, The ranges between 0.3 and 0.

8.

3. The trailing suction hopper dredger bucket excavation yield calculation method according to claim 1, characterized in that, The values ​​of k1 and k2 vary depending on the type of rake teeth and the soil type. For silty soil, the values ​​are shown in the table below: 。

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