A jet jet control method for submarine cable laying machines

Abstract

This invention relates to a jetting control method for a submarine cable laying machine, comprising: obtaining a relationship between the breaking depth and the nozzle diameter, soil strength, nozzle jetting speed, nozzle horizontal movement speed, and jetting water pressure; substituting the known soil strength and preset breaking depth into the above relationship to calculate the conditions that need to be met between the nozzle diameter, nozzle jetting speed, nozzle horizontal movement speed, and jetting water pressure; the cable laying machine performing construction based on the parameters calculated above; and finally comparing the actual breaking depth with the preset breaking depth, adjusting one or more of the nozzle diameter, nozzle jetting speed, and / or jetting water pressure to ensure that the current cable laying machine meets the construction requirements. The advantages of this invention are: it can meet different laying depths, provides a theoretical basis for the design of the jetting arm and the selection of the high-pressure pump for the cable laying machine, and maximizes cable laying efficiency.

Description

Technical Field

[0001] This invention relates to the field of marine engineering technology, and in particular to a jetting control method for a submarine cable laying machine. Background Technology

[0002] Currently, cable-laying machines are widely used in submarine cable laying construction. Their working principle is as follows: high-pressure water jets from nozzles connected to high-pressure pumps scour the seabed, forming trenches of a certain depth. Submarine cables are then placed into the trenches, which are automatically filled by ocean currents, thus achieving the purpose of laying submarine cables.

[0003] Currently, the theory of high-pressure jet blasting for soil breaking is not yet mature, making it difficult to meet the trenching requirements of different soil types. Upon investigation, a Chinese utility model patent with patent number ZL201320212115.8 (authorization announcement number CN203242968U) discloses a deep-buried cable laying machine for submarine cables. This cable laying machine equips the mechanical plow body and the hydraulic soil breaking plow body with hydraulic drive devices to achieve adjustable burial depth and adapt to the trenching requirements of different soil types.

[0004] However, since the aforementioned cable-laying machine adjusts the burial depth mechanically, it is not applicable to other existing cable-laying machines. Therefore, in many cases, workers can only design the nozzle specifications, nozzle arrangement, and high-pressure pump head and flow rate parameters of the existing cable-laying machine based on engineering experience to meet different burial depths. However, this experience-based approach has the following limitations: 1. Choosing excessively large high-pressure pump parameters leads to energy waste; 2. Choosing excessively small high-pressure pump parameters causes the cable-laying machine to fail to achieve the expected performance indicators; 3. The number and size of the nozzles are mismatched with the high-pressure pump, resulting in reduced soil breaking effect; 4. The selected trenching speed and soil strength are mismatched during actual construction, failing to reach the desired trenching depth.

[0005] Therefore, further improvements to existing technologies are needed. Summary of the Invention

[0006] The technical problem to be solved by the present invention is to provide a jetting control method for submarine cable laying machines that can guide the selection of nozzles to improve cable laying efficiency, in view of the above-mentioned prior art.

[0007] The technical solution adopted by the present invention to solve the above-mentioned technical problems is as follows: a jetting control method for a submarine cable laying machine, the cable laying machine including a jetting arm with nozzles, characterized by including the following steps:

[0008] Step 1: Conduct experiments on the cable-laying machine to obtain the relationship between the soil breaking depth and the nozzle diameter, soil strength, nozzle spraying speed, nozzle horizontal movement speed and sprayed water pressure.

[0009] The specific experimental steps for the cable-laying machine are as follows:

[0010] Step 1-1: Using the same nozzle in a static state, spray perpendicularly to a soil layer of the same strength at different spraying speeds, and obtain the relationship between the spraying speed of the nozzle and the pressure of the sprayed water flow.

[0011] Step 1-2: Keep the soil strength and nozzle spraying speed constant, change the nozzle diameter in step 1-1, and obtain the relationship between the soil breaking depth and the nozzle diameter.

[0012] Steps 1-3: Keep the nozzle diameter and spray speed constant, change the soil strength, and obtain the relationship between the soil breaking depth and the soil strength.

[0013] Steps 1-4: Keep the soil strength, nozzle spraying speed and nozzle diameter constant, move the nozzle horizontally, and gradually increase the horizontal movement speed of the nozzle from 0 to obtain the relationship between the soil breaking depth and the horizontal movement speed of the nozzle.

[0014] Steps 1-5: Perform coupling analysis on the relationships in steps 1-1 to 1-4 to obtain the relationships satisfied by the soil breaking depth with nozzle diameter, soil strength, nozzle spraying speed, nozzle horizontal movement speed and sprayed water pressure.

[0015] Step 2: Before the cable laying machine is installed, substitute the known soil strength and the preset breaking depth into the relationship in Step 1 to calculate the conditions that need to be met between the nozzle diameter, the nozzle spraying speed, the nozzle horizontal movement speed and the sprayed water pressure.

[0016] Step 3: The cable-laying machine is used for construction with the obtained nozzle diameter, nozzle spray speed, nozzle horizontal movement speed and spray water pressure.

[0017] Step 4: Determine whether the actual breaking depth is less than the preset breaking depth. If so, increase one or more of the following: nozzle diameter, nozzle spray speed, and / or spray water pressure, and proceed to Step 3 to carry out construction again. If not, proceed to Step 5.

[0018] Step 5: Determine whether the difference between the actual breaking depth and the preset breaking depth exceeds the preset value. If so, reduce one or more of the following: nozzle diameter, nozzle spray speed, and / or spray water pressure, and proceed to step 3 to carry out construction again. If not, the current cable laying machine can meet the construction requirements, and the cable laying machine will carry out construction with the current parameters.

[0019] Specifically, the injection speed V of the nozzle in step 1-1 射流 With the pressure P of the jetting water flow压力 The relationship between them is:

[0020]

[0021] Where K1 is the calibration coefficient, and K1 is a constant; ρ is the density of water.

[0022] Furthermore, in steps 1-5, the soil breaking depth H is related to the nozzle diameter D and the soil strength P. 土层 The jet velocity V of the nozzle 射流 Horizontal movement speed of nozzle V 移动 and the water pressure P of the jet 压力 The relationship between them is:

[0023] H = D * K2 * (V 射流 / V 移动 )*K3*(P 压力 / P 土层 )

[0024] Where K2 is the speed calibration coefficient and K3 is the pressure calibration coefficient, both of which are constants.

[0025] Specifically, in steps 1-4, the horizontal movement speed of the nozzle corresponding to the sudden change in the trench of the soil spraying is obtained, and the horizontal movement speed of the nozzle is recorded as the maximum speed of the nozzle movement. Then, the horizontal movement speed of the nozzle is controlled not to exceed the maximum speed during the construction of the cable laying machine.

[0026] Preferably, the nozzle is a conical nozzle.

[0027] Compared with the prior art, the advantages of this invention are as follows: By exploring the relationship between the soil breaking depth and the nozzle diameter, soil strength, nozzle spray speed, nozzle horizontal movement speed and spray water pressure, the strength of the seabed soil layer, the range of movement speed that the cable laying machine needs to reach and the maximum soil breaking depth are clear parameters. The nozzle diameter, nozzle water pressure and water flow velocity can be calculated through the relationship, which can meet different burial depths. This provides a theoretical basis for the design of the spray arm of the cable laying machine and the selection of high-pressure pump, and maximizes the cable laying efficiency. Attached Figure Description

[0028] Figure 1 This is a cross-sectional view of the nozzle in an embodiment of the present invention;

[0029] Figure 2 This is a diagram showing the changes in nozzle spray velocity and soil penetration depth when the spray water pressure changes in an embodiment of the present invention.

[0030] Figure 3 This is a diagram showing the change in soil penetration depth when only the nozzle diameter is changed in an embodiment of the present invention.

[0031] Figure 4 This is a diagram showing the change in the soil penetration depth when only the soil strength is changed in an embodiment of the present invention.

[0032] Figure 5 This is a diagram showing the change in the soil penetration depth as the horizontal movement speed of the nozzle gradually increases from 0 in an embodiment of the present invention. Detailed Implementation

[0033] The present invention will be further described in detail below with reference to the accompanying drawings and embodiments.

[0034] In this embodiment, the submarine cable laying machine includes a spray arm with nozzles, such as... Figure 1 As shown, the nozzle is a conical nozzle, which includes a straight section 1 adjacent to the nozzle orifice and a conical section 2 connected to the straight section 1. The contraction angle of the conical section 2 is 13°. The length L of the straight section 1 is 2.5 times the nozzle diameter D. This results in a larger impact force of the water, which is beneficial for breaking through the soil layer. The above-mentioned nozzle diameter is referred to as the nozzle diameter below.

[0035] Other structures of the cable-laying machine can use existing technologies, which will not be elaborated here.

[0036] The jetting control method for submarine cable laying machines in this embodiment includes the following steps:

[0037] Step 1: Conduct experiments on the cable-laying machine to obtain the relationship between the soil breaking depth and the nozzle diameter, soil strength, nozzle spraying speed, nozzle horizontal movement speed and sprayed water pressure.

[0038] The specific experimental steps for the cable-laying machine are as follows:

[0039] Step 1-1: Using the same nozzle in a static state, spray perpendicularly to a soil layer of the same strength at different spraying speeds, and obtain the relationship between the spraying speed of the nozzle and the pressure of the sprayed water flow.

[0040] In this embodiment, the nozzle injection speed V in step 1-1 射流 With the pressure P of the jetting water flow 压力 The relationship between them is:

[0041]

[0042] Where K1 is the calibration coefficient, and K1 is a constant; ρ is the density of water;

[0043] like Figure 2 As shown, Figure 2 (a) The water pressure used in the jet is P1 水压 The jet speed is V1 射流The depth of the soil layer is H1; Figure 2 (b) The water pressure used in the jet is P2 水压 The jet speed is V2 射流 The depth of the soil layer is H1; where P1 水压 <P2 水压； Discover when V 射流 After increasing from 0 to a certain value, the soil layer begins to break down, creating a crater. As V increases... 射流 As the velocity increases, the soil layer is damaged and the pit becomes larger and deeper. The depth of soil penetration is denoted as H. Therefore, the jetting velocity is directly proportional to the depth of soil penetration.

[0044] Step 1-2: Keep the soil strength and nozzle spraying speed constant, change the nozzle diameter in step 1-1, and obtain the relationship between the soil breaking depth and the nozzle diameter.

[0045] Figure 3 (a) The diameter of the nozzle is D1, and the depth of the soil layer is H1; Figure 3 (b) The nozzle diameter is D2, and the soil penetration depth is H2; where D1 < D2, as shown in the figure. Figure 3 As shown, it was found that when the nozzle diameter is increased, the soil breaking depth increases, i.e., H1 < H2. Therefore, the nozzle diameter and the soil breaking depth are directly proportional.

[0046] Steps 1-3: Keep the nozzle diameter and spray speed constant, change the soil strength, and obtain the relationship between the soil breaking depth and the soil strength.

[0047] Figure 4 (a) The strength of the middle soil layer is P1 土层 The depth of the soil layer is H1; Figure 4 (b) The strength of the intermediate soil layer is P2 土层 The depth of the soil layer is H2; where P1 土层 >P2 土层 ,like Figure 4 As shown, it was found that when the soil strength was increased, the penetration depth increased, i.e., H1 < H2. Figure 4 H1 and Figure 3 H1 in the equation can be the same value or different values, mainly to express the change in soil penetration depth in 4(a) and 4(b), so soil strength and soil penetration depth are inversely proportional;

[0048] Steps 1-4: Keep the soil strength, nozzle spraying speed and nozzle diameter constant, move the nozzle horizontally, and gradually increase the horizontal movement speed of the nozzle from 0 to obtain the relationship between the soil breaking depth and the horizontal movement speed of the nozzle.

[0049] like Figure 5 As shown, the jet velocity V of a certain nozzle射流 Vertical impact on soil layer, nozzle horizontal movement speed V 移动 As the pressure gradually increases from 0, the pits caused by soil failure become shallower. The bottom of the trench in the soil failure profile initially forms a straight line, but this line decreases as the nozzle moves horizontally at a speed V. 移动 After increasing to a certain number, the bottom of the groove begins to curve. The horizontal movement speed V of the nozzle corresponding to the abrupt change at the bottom of the groove is then determined. 移动 , is recorded as the maximum speed of nozzle movement. During cable laying, the horizontal movement speed of the nozzle should be controlled not to exceed this maximum speed.

[0050] Soil layer strength P 土层 The larger the value, the larger the V required. 射流 and a smaller nozzle horizontal movement speed V 移动 Only then can the same destructive effect be produced;

[0051] Steps 1-5: Perform coupling analysis on the relationships in steps 1-1 to 1-4 to obtain the relationship between the soil breaking depth and the nozzle diameter, soil strength, nozzle spraying speed, nozzle horizontal movement speed and sprayed water pressure; this coupling analysis can be a fitting method commonly used in mathematics.

[0052] In this embodiment, the soil breaking depth H is related to the nozzle diameter D and the soil strength P. 土层 The jet velocity V of the nozzle 射流 Horizontal movement speed of nozzle V 移动 and the water pressure P of the jet 压力 The relationship between them is:

[0053] H = D * K2 * (V 射流 / V 移动 )*K3*(P 压力 / P 土层 )

[0054] Where K2 is the speed calibration coefficient, K3 is the pressure calibration coefficient, and both K2 and K3 are constants;

[0055] Step 2: Before the cable laying machine is installed, substitute the known soil strength and the preset breaking depth into the relationship in Step 1 to calculate the conditions that need to be met between the nozzle diameter, the nozzle spraying speed, the nozzle horizontal movement speed and the sprayed water pressure.

[0056] Step 3: The cable-laying machine is used for construction with the obtained nozzle diameter, nozzle spray speed, nozzle horizontal movement speed and spray water pressure.

[0057] Step 4: Determine whether the actual breaking depth is less than the preset breaking depth. If so, increase one or more of the following: nozzle diameter, nozzle spray speed, and / or spray water pressure, and proceed to Step 3 to carry out construction again. If not, proceed to Step 5.

[0058] Step 5: Determine whether the difference between the actual breaking depth and the preset breaking depth exceeds the preset value. If so, reduce one or more of the following: nozzle diameter, nozzle spray speed, and / or spray water pressure, and proceed to step 3 to carry out construction again. If not, the current cable laying machine can meet the construction requirements, and the cable laying machine will carry out construction with the current parameters.

[0059] Before cable-laying machine construction, the strength of the seabed soil, the required trenching speed range and maximum trenching depth of the cable-laying machine are clearly defined parameters. Through the above relationships, the nozzle diameter, nozzle water pressure and water jet velocity can be calculated, providing a theoretical basis for the design of the jetting arm of the jetting trenching machine and the selection of the high-pressure pump. This has an important guiding role in cable-laying machine construction and maximizes cable-laying efficiency.

[0060] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the technical principles of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A jetting control method for a submarine cable laying machine, the cable laying machine comprising a jetting arm with nozzles, characterized in that... Includes the following steps: Step 1: Conduct experiments on the cable-laying machine to obtain the relationship between the soil breaking depth and the nozzle diameter, soil strength, nozzle spraying speed, nozzle horizontal movement speed and sprayed water pressure. The specific experimental steps for the cable-laying machine are as follows: Step 1-1: Using the same nozzle in a stationary state, spray perpendicularly to a soil layer of the same strength at different spray velocities, and obtain the spray velocity V of the nozzle. 射流 With the pressure P of the jetting water flow 压力 The relation between them is: Where K1 is the calibration coefficient, K2 is a constant; ρ is the density of water; Step 1-2: Keep the soil strength and nozzle spraying speed constant, change the nozzle diameter in step 1-1, and obtain the relationship between the soil breaking depth and the nozzle diameter. Steps 1-3: Keep the nozzle diameter and spray speed constant, change the soil strength, and obtain the relationship between the soil breaking depth and the soil strength. Steps 1-4: Keep the soil strength, nozzle spraying speed and nozzle diameter constant, move the nozzle horizontally, and gradually increase the horizontal movement speed of the nozzle from 0 to obtain the relationship between the soil breaking depth and the horizontal movement speed of the nozzle. Steps 1-5: Perform coupling analysis on the relationships in steps 1-1 to 1-4 to obtain the relationship between the soil breaking depth H, nozzle diameter D, and soil strength P. 土层 The jet velocity V of the nozzle 射流 Horizontal movement speed of nozzle V 移动 and the water pressure P of the jet 压力 The relation between them is: H=D*K2*(V 射流 / V 移动 )*K3*(P 压力 / P 土层 ) Where K2 is the speed calibration coefficient, K3 is the pressure calibration coefficient, and both K2 and K3 are constants; Step 2: Before the cable laying machine is installed, substitute the known soil strength and the preset breaking depth into the relationship in Step 1 to calculate the conditions that need to be met between the nozzle diameter, the nozzle spraying speed, the nozzle horizontal movement speed and the sprayed water pressure. Step 3: The cable-laying machine is used for construction with the obtained nozzle diameter, nozzle spray speed, nozzle horizontal movement speed and spray water pressure. Step 4: Determine whether the actual breaking depth is less than the preset breaking depth. If so, increase one or more of the following: nozzle diameter, nozzle spray speed, and / or spray water pressure, and proceed to Step 3 to carry out construction again. If not, proceed to Step 5. Step 5: Determine whether the difference between the actual breaking depth and the preset breaking depth exceeds the preset value. If so, reduce one or more of the following: nozzle diameter, nozzle spray speed, and / or spray water pressure, and proceed to step 3 to carry out construction again. If not, the current cable laying machine can meet the construction requirements, and the cable laying machine will carry out construction with the current parameters.

2. The jet spray control method for a submarine cable laying machine according to claim 1, characterized in that: In steps 1-4, the horizontal movement speed of the nozzle corresponding to the sudden change in the trench of the soil spraying is also obtained. This horizontal movement speed of the nozzle is recorded as the maximum speed of the nozzle movement. During the construction of the cable laying machine, the horizontal movement speed of the nozzle is controlled not to exceed this maximum speed.

3. The jet spray control method for a submarine cable laying machine according to claim 1 or 2, characterized in that: The nozzle is a conical nozzle.

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