CN115358085A - Determination method for jet flow equipment for direct-buried submarine cable deprotection work - Google Patents
Determination method for jet flow equipment for direct-buried submarine cable deprotection work Download PDFInfo
- Publication number
- CN115358085A CN115358085A CN202211061847.1A CN202211061847A CN115358085A CN 115358085 A CN115358085 A CN 115358085A CN 202211061847 A CN202211061847 A CN 202211061847A CN 115358085 A CN115358085 A CN 115358085A
- Authority
- CN
- China
- Prior art keywords
- jet
- submarine cable
- direct
- buried
- model
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Pending
Links
Images
Classifications
-
- G—PHYSICS
- G06—COMPUTING; CALCULATING OR COUNTING
- G06F—ELECTRIC DIGITAL DATA PROCESSING
- G06F30/00—Computer-aided design [CAD]
- G06F30/20—Design optimisation, verification or simulation
Landscapes
- Engineering & Computer Science (AREA)
- Physics & Mathematics (AREA)
- Theoretical Computer Science (AREA)
- Computer Hardware Design (AREA)
- Evolutionary Computation (AREA)
- Geometry (AREA)
- General Engineering & Computer Science (AREA)
- General Physics & Mathematics (AREA)
- Electric Cable Installation (AREA)
Abstract
The invention provides a method for determining jet equipment for the deprotection work of a direct-buried submarine cable, which is characterized in that the physical properties of soil of the deprotection work of the direct-buried submarine cable are measured by a test method, and a jet erosion simulation model of the deprotection work of the direct-buried submarine cable is established based on a water jet technology, so that the working conditions of the soil and the water area of the direct-buried submarine cable in the deprotection work and jet key parameters are considered, the direct-buried submarine cable subjected to water jet erosion is subjected to stress analysis, and the submarine cable is prevented from being secondarily damaged by high-speed jet; according to the method, the accurate determination of key jet flow parameters is realized through the analysis of the jet flow ground breaking simulation results of the directly-buried submarine cable under different working conditions, and accurate and reliable bases are provided for the type selection and parameter design of jet flow equipment.
Description
Technical Field
The invention belongs to the technical field of submarine cable engineering, and relates to a method for determining submarine cable rush-repair equipment.
Background
Submarine cables are called submarine cables for short, and are important components of offshore wind power transmission grid connection, cross-sea-area international power grid interconnection, sea island and ocean engineering power supply. The submarine cable is easily damaged by natural factors and human factors at the seabed, the damage of the submarine cable can cause low-frequency accidents of a power grid, and large-area power failure is easily caused, so that the rush-repair work of the submarine cable needs to be completed in the shortest time, and the serious influence on economy, life and the like is avoided. The submarine cable emergency repair is mainly divided into four parts, namely submarine cable covering cleaning, submarine cable underwater cutting, submarine cable fishing and submarine cable playback. The deprotection work of directly burying submarine cable cover clearance mainly is to the deep water district towards buried segment submarine cable, and the cover of dashing buried segment submarine cable is mostly the soil body. In the protection removing work of cleaning the directly-buried submarine cable covering, the mode of carrying out jet erosion on the protective layer above the directly-buried submarine cable through jet equipment is the most efficient, economic and safe method, and the jet erosion is utilized to erode the soil body to expose the submarine cable, so that the subsequent cutting work can be conveniently carried out.
At present, in the deprotection work of the direct-buried submarine cable, there are two main methods for selecting the jet device: firstly, the type selection is carried out on the equipment by depending on experience, and the method has no accurate theoretical basis, so that the type selection is often unreasonable, and the serious waste of resources is caused; secondly, the model of the equipment is determined by a trial operation experiment method, because the time of the jet acting on the soil body is short, the water body is turbid, the information acquisition in the jet process is difficult, only the final jet deprotection result can be obtained, the mechanism analysis is difficult to be carried out on the final jet deprotection result, the guiding significance of the experiment result on the actual construction is not great, and the unnecessary construction cost is caused.
Disclosure of Invention
In order to solve the problems in the background art, the invention provides a method for determining a jet device for the deprotection work of a direct-buried submarine cable.
The technical scheme of the invention comprises the following steps:
the method comprises the following steps of firstly, determining the physical characteristics of soil of a soil body of a protective working section of a direct-buried submarine cable, wherein the physical characteristics comprise the following steps: specific gravity, density, water content, volume modulus, shear modulus, friction angle, cohesion and critical failure pressure;
step two, according to the physical characteristics of the soil and the necessary conditions of the jet destruction of the soil body: the average acting force of the jet flow in the half-width range of the surface of the soil body is larger than the critical destruction pressure of the soil body, and the key parameters of the jet flow are preliminarily estimated, wherein the key parameters comprise: velocity v of the nozzle outlet 0 Diameter d of a nozzle outlet and target distance L of water jet;
step three, establishing a direct-buried submarine cable jet flow ground breaking model in ANSYS according to the preliminarily estimated jet flow key parameters, dividing grids, and exporting a K file;
modifying the K file in the LS _ PREPOST, and defining materials, boundary conditions, contact, load and control equations by using an ALE algorithm to obtain a modified K file;
step five, importing the corrected K file into LS _ DYAN to perform solving analysis to obtain a simulation model;
step six, carrying out post-processing on the simulation model in LS _ PREPOS to obtain a simulation result of the deprotection work of the directly-buried submarine cable;
step seven, analyzing the simulation result, if the requirement of the direct-buried submarine cable deprotection work is met, primarily estimating jet flow key parameters in the step two to serve as accurate jet flow key parameters, if the requirement of the direct-buried submarine cable deprotection work is not met, adjusting the primarily estimated jet flow key parameters, and re-executing the step three to the step six until the accurate jet flow key parameters are determined;
step eight, determining parameters of the jet flow equipment according to the accurate jet flow key parameters, wherein the method comprises the following steps: the water pump lift, the jet diameter, the nozzle installation mode and the water pump model selection guide the jet equipment model selection and parameter design.
In the first step, in the measurement of the physical properties of the soil, the specific gravity is measured by a pycnometer method, the density is measured by a cutting ring method, the water content is measured by a drying method, and the shear modulus and the volume modulus are measured by a penetrometer and K 0 The consolidation test is used for measuring, the friction angle and the cohesive force are measured by adopting a direct shear test, and the critical failure stress is measured by adopting a triaxial compression test.
Furthermore, in the second step, the average acting force of the jet flow in the half-width range of the soil surface
Comprises the following steps:
wherein v is 0 Is the velocity of the nozzle outlet, ρ is the density of the seawater, d is the nozzle outlet diameter, α is the water jet divergence angle of the nozzle, l 0 L is the target distance of the water jet.
Furthermore, in the third step, in the establishment of the direct-buried submarine cable jet flow soil breaking model, firstly, the size of 1/2 jet flow model is preliminarily established, then, SOID _164 entity units are adopted to give 4 kinds of hollow materials, a jet flow source and a water area share a node, then, a soil body model and a submarine cable model are established, the soil body and the submarine cable require the sharing of the node, and the model size is required to eliminate the influence of the boundary effect; in the grid division, the model is subjected to grid division, and the water area grid and the soil body grid near the jet flow damage are encrypted.
Furthermore, in the fourth step, the step of modifying the K file is as follows:
(1) definition of materials: in the soil material model, inputting the physical soil characteristics obtained in the first step into a keyword MAT _147_FHWA _SOILand an erosion algorithm MAT _ ADD _ ERODION, wherein the soil unit algorithm adopts SECTION _ SOILD, and the parameters are kept as default; the key word of the material model of the directly-buried submarine cable is MAT _ RIGID, which comprises the following steps: density, young modulus and Poisson ratio, a unit algorithm of the direct-buried submarine cable adopts SECTION _ SOILD, and parameters are kept to be default; the key word of the jet source and water area model is MAT _009 null, the state equation is defined as EOS _ GRUNERSEN, the ELFOR of the water area and jet source unit algorithm SECTION _ SOILD is set as a fixed value, and the rest is kept as default; endowing the parameters to a model, respectively defining ALE substances for a jet flow source and a water area, wherein the keyword is ALE _ MULTI _ MATERIAL _ GROUP, and adopting an ALE algorithm;
(2) defining boundary conditions: the bottom of the soil body is subjected to full constraint, the normal direction of the symmetrical plane of the 1/2 jet model limits translation, and the other two directions limit rotation; applying NON-reflection BOUNDARY conditions to the side surfaces and the bottom ends of the soil body and the water area to simulate an infinite area in space, wherein the keyword is named as BOUNDARY _ NON _ feedback;
(3) defining the contact: the soil body, the directly-buried submarine cable, the jet source and the water area are IN fluid-solid coupling through keyword such as CONSTRAINED _ LARGE _ IN _ SOLID, the SLAVE plane SLAVE is a PART consisting of the soil body and the directly-buried submarine cable, and the MASTER plane MASTER is a PART consisting of the water area and the jet source;
(4) defining the load: the jet flow continuous jet is characterized in that fluid with vertical speed continuously appears at the outlet of a nozzle, and the jet flow source for continuous jet can be realized by setting a jet speed function curve and keywords such as bound _ preceding _ movement _ SET and associating the curve with the speed value of the jet flow;
(5) defining a governing equation: volume VISCOSITY CONTROL _ BULK _ viscoat, held by default; ALE and Euler calculation sets global CONTROL parameters such as CONTROL _ ALE, and defaults are kept; controlling the HOURGLASS _ hour _ glass to keep default; the calculated time, CONTROL _ terminal, the time step, CONTROL _ time, and the output frequency, data base _ BINARY _ D3PLOT are all determined according to the requirements of the protection removal work of the direct-buried submarine cable.
Further, in the sixth step, the simulation result of the deprotection operation of the direct-buried submarine cable in the sixth step includes: (1) extracting time-displacement historical data of the soil unit, and drawing a time-displacement curve in the jet flow direction to obtain soil erosion displacement; (2) measuring the maximum damage width of a unit above the directly-buried submarine cable; (3) and extracting historical data of stress and strain of the model direct-buried submarine cable unit, storing the historical data into a model stress-strain file, extracting the model stress-strain file from the Xyplot, drawing a model stress-strain curve, and obtaining a comparison graph of the model stress-strain curve and an actual direct-buried submarine cable stress-strain curve.
Furthermore, in the seventh step, the case that the simulation result does not meet the requirements of the direct-buried submarine cable deprotection work and the preliminarily estimated jet key parameters need to be adjusted includes: (1) if the soil erosion displacement of the time-displacement curve in the jet flow direction does not reach the burying depth of the directly buried sea cable, the velocity v of the nozzle outlet needs to be increased 0 Or reducing the target distance L of the water jet; (2) the maximum damage width is smaller than the diameter of the directly buried submarine cable, and the diameter d of the outlet of the jet nozzle needs to be increased; (3) in the comparison graph of the stress-strain curve of the model and the stress-strain curve of the actual directly-buried submarine cable, if the directly-buried submarine cable in the model is damaged, the speed v of the outlet of the nozzle needs to be reduced 0 Target distance of the water jet or nozzle outlet diameter d.
Furthermore, in the eighth step, the velocity v of the nozzle outlet is determined 0 Determining the water pump lift of the jet flow equipment, determining the diameter of a nozzle of the jet flow equipment according to the diameter d of the outlet of the nozzle, and guiding the installation mode of the nozzle of the jet flow equipment according to the target distance L of the water jet flow; according to jet velocity and jetThe flow diameter can calculate the flow of the emergent flow, so that the flow of the water pump can be determined, and the model selection design of the water pump of the jet flow equipment can be guided.
Compared with the prior art, the physical characteristics of soil of the soil for the deprotection work of the directly-buried submarine cable are measured by a test method, and the jet erosion simulation model for the deprotection work of the directly-buried submarine cable is established based on the water jet technology, so that the soil and water working conditions and jet critical parameters of the directly-buried submarine cable in the deprotection work are considered, the directly-buried submarine cable subjected to water jet erosion is subjected to stress analysis, and the submarine cable is prevented from being secondarily damaged by high-speed jet; according to the method, the jet flow ground breaking simulation results of the directly-buried submarine cable under different working conditions are analyzed, so that the jet flow key parameters are accurately determined, and accurate and reliable bases are provided for jet flow equipment model selection and parameter design.
Drawings
FIG. 1 is a flow chart of the present invention.
Fig. 2 is a schematic diagram of a model for direct-buried submarine cable jet flow ground breaking.
Wherein: 1-a jet source; 2-water area; 3-soil body; 4-direct-buried submarine cable.
Detailed Description
The embodiments of the present invention will be described in detail with reference to the accompanying drawings, but the embodiments are not limited to the invention, and the advantages of the invention will be understood more clearly by the description. All modifications which can be derived or suggested by a person skilled in the art from the disclosure of the present invention are to be considered within the scope of the invention. The positional relationships described in the embodiments are all the same as those shown in the drawings, and other portions not described in detail in the embodiments are all the related art.
Examples
In this embodiment, the implementation of the present invention is further specifically described by using a silt-based soil body in south China sea as a protective layer of a direct-buried submarine cable.
As shown in fig. 1, the method for determining the jet device for the direct-buried submarine cable deprotection operation specifically includes the following steps:
(1) Determining soil physical characteristics of a protective covering
In the measurement of physical properties of soil, the density is measured by a pycnometer method, the density is measured by a cutting ring method, the water content is measured by a drying method, and the shear modulus and the volume modulus are measured by a penetrometer and K 0 The consolidation test is used for measuring the friction angle and the cohesive force, the direct shear test is used for measuring the friction angle and the cohesive force, and the triaxial compression test is used for measuring the critical failure stress.
The physical properties of the soil were obtained by measurement: : specific gravity of 2.64, water content of 32%, and density of 1.88g/cm 3 The shear modulus is 2.1e-5Mbar, the bulk modulus is 4.5e-5Mbar, the friction angle is 0.366rad, the cohesive force is 1.5e-7Mbar, and the ultimate failure stress of the soil is 1e-6Mbar.
(2) Preliminary estimation of jet flow key parameters and soil body parameters
Average acting force of jet flow on soil surface within half-width range
Comprises the following steps:
wherein v is 0 Is the velocity of the nozzle outlet, ρ is the density of the seawater, d is the nozzle outlet diameter, α is the water jet divergence angle of the nozzle, l 0 Is the constant velocity core length of the water jet, and L is the target distance of the water jet.
The ultimate stress of the soil body which is known from (1) to be destroyed is 1e-6Mbar, namely 0.1Mpa, and the condition that the soil body can be destroyed is the average acting force of the jet flow in the half-width range of the surface of the soil body
Greater than the ultimate failure stress of the soil, in this example
In the actual construction process, the type of the nozzle is mostly a conical-straight nozzle, and the diffusion angle alpha =16 degrees and the constant speed core length l are adopted 0 ＝(4.8-8)dIn this example,. L 0 =4.8d. From the above formula, the main parameter affecting the action of the jet is the velocity v of the nozzle outlet 0 Diameter d of a nozzle outlet and target distance L of water jet, wherein the diameter d =0.3cm of the nozzle outlet and the target distance L =1cm of the water jet are taken primarily in the embodiment and need to meet the requirements
The velocity v of the nozzle outlet 0 It is required to be larger than 15.6m/s, so v is first taken in this embodiment 0 =33m/s numerical simulations are performed, if necessary adjustments are made.
In this embodiment, the following is obtained by calculation:
preliminary estimation of jet key parameters: velocity v of the nozzle outlet 0 =33m/s, nozzle outlet diameter d =0.3cm, and target distance L =1cm of the water jet.
(3) Making K documents
Preliminarily determining the size of a 1/2 jet model, wherein the size of a soil body 3 model is 6cm long, 4cm wide and 9cm high; the size of the water area 2 is 5cm long, 5cm wide and 10cm high; the diameter of the jet source 1 is 0.3cm, the height is 0.1cm, and the target distance of the water jet is 1cm; the directly buried submarine cable 4 model is 0.5cm in diameter and 6cm in length.
Dividing grids in ANSYS _ APDL, defining a three-dimensional entity unit SOLID _164 unit, and endowing 4 empty materials; the jet source 1 and the water area 2 share a node, a soil body model and a submarine cable model are established, the soil body 3 and the submarine cable 4 are required to share a node, and the size of the soil body model is required to eliminate the influence of a boundary effect; and finally, carrying out grid division on the model, and encrypting the water area grid and the soil body grid near the jet flow damage. The number of jet source 1 units is 95, the number of water area 2 units is 240576, the number of soil body 3 units is 162060, the number of direct-buried submarine cable 4 units is 2820, and the model is as shown in fig. 2, and a K file is exported and stored.
(3) Modifying K files
Import K file to LS _ presort.
(1) Definition of materials: inputting the physical characteristics of the soil in the step (1) into a keyword MAT _147_FHWA _SOILand an erosion algorithm MAT _ ADD _ ERODION in the soil material model, wherein the soil unit algorithm adopts SECTION _ SOILD, and the parameters are kept to be default; the key word of the material model of the directly-buried submarine cable 4 is MAT _ RIGID, the density is 2.7, the young modulus is 7.0, the poisson ratio is 0.3 in the embodiment, the unit algorithm of the directly-buried submarine cable 4 adopts SECTION _ soi id, and the parameters are kept to be default; the key words of the material model of the jet source 1 and the water area 2 are MAT _009 null, the density is 1.0, meanwhile, the state equation EOS _ GRUNERSEN is defined, the ELFORM of the unit algorithm of the jet source 1 and the water area 2, SECTION _ SOLD is set as 11, and the rest is kept as the default. Assigning the parameters to different models, PART; respectively defining ALE substances for the jet source 1 and the water area 2, wherein the keywords are ALE _ MULTI _ MATERIAL _ GROUP, and adopting an ALE algorithm.
(2) Defining boundary conditions: the bottom of the soil body is subjected to full constraint, the normal direction of the symmetrical plane of the 1/2 jet model limits translation, and the other two directions limit rotation; NON-reflective BOUNDARY conditions are applied to the sides and bottom of the soil 3 and water 2 to simulate an infinite area in space, and the keyword is bound _ NON _ refelction.
(3) Defining the contact: the soil 3 and the directly-buried submarine cable 4 form a PART, the water area 2 and the jet source 1 form a PART, the soil 3 and the directly-buried submarine cable 4 are IN fluid-solid coupling with the jet source 1 and the water area 2 through keyword structured _ LAGRANGE _ IN _ solid definition, the SLAVE plane SLAVE is the PART formed by the soil 3 and the directly-buried submarine cable 4, and the MASTER plane MASTER is the PART formed by the water area 2 and the jet source 1.
(4) Defining the load: the jet continuous jet is characterized in that the fluid with vertical speed continuously appears at the nozzle outlet, and the jet source for continuous jet can be realized by setting a jet speed function curve and a keyword, namely, BOUNDARY _ preceding _ movement _ SET, and relating the curve with the speed value of the jet fluid, wherein the jet speed is equal to the speed of the nozzle outlet and is 33m/s.
(5) Defining a governing equation: BULK VISCOSITY CONTROL _ BULK _ VISCOSITY, kept by default; ALE and Euler calculation sets global CONTROL parameters such as CONTROL _ ALE, and defaults are kept; controlling HOURGLASS _ HOURGLASS, keeping default; calculating time, CONTROL _ TERMINATION, and calculating the time length of 2000us; step of time, CONTROL _ time, endim is 10; the output frequency × DATABASE _ BINARY _ D3PLOT, DT is 25.
And finally obtaining a corrected K file.
(5) Preparing a simulation model
In LS _ DYNA software, a Solver menu is opened, a Start LS _ DYNA Analysis command button is selected, a correction K file is recorded in a Start Input and Output dialog box for solving and Analysis, and a simulation model is obtained through simulation Analysis.
(6) Obtaining simulation results
And (4) performing post-processing on the simulation model obtained in the step (5) in LS _ PREPOST, and opening an LS _ DYNA Binary Plot file. Firstly, extracting time-displacement historical data of a soil unit, drawing a time-displacement curve in the jet flow direction, observing soil erosion displacement, and judging whether the soil erosion displacement reaches the submarine cable burying depth or not; secondly, measuring the maximum damage width of a unit close to the upper part of the directly-buried submarine cable 4, and comparing whether the maximum damage width is larger than the diameter of the directly-buried submarine cable 4; and thirdly, extracting historical data of stress and strain of the unit of the model direct-buried submarine cable 4, storing the historical data into a model stress-strain file, then extracting the model stress-strain file from the Xyplot to draw a model stress-strain curve, and comparing the model stress-strain curve with an actual stress-strain curve of the direct-buried submarine cable to analyze the damaged condition of the submarine cable.
And obtaining a simulation result through the post-processing.
(7) Re-determination of jet key parameters
Obtained in (2) above is a preliminary estimate of the jet critical parameters: velocity v of the nozzle outlet 0 =33m/s, nozzle outlet diameter d =0.3cm, and target distance L =1cm of the water jet. The primarily estimated jet flow key parameters may not meet the requirements of the direct-buried submarine cable deprotection work, so that the simulation result obtained by the post-processing in the step (6) needs to be analyzed, and the jet flow key parameters are determined again.
Specifically, the simulation result obtained by the post-processing in the step (6) is analyzed, whether the jet flow key parameter meets the requirement or not is evaluated through the simulation result, if the jet flow key parameter meets the requirement of the direct-buried submarine cable deprotection work, the jet flow key parameter preliminarily estimated in the step two is used as the accurate jet flow key parameter, if the jet flow key parameter does not meet the requirement of the direct-buried submarine cable deprotection work, the preliminarily estimated jet flow key parameter is adjusted, and the steps from (3) to (6) are executed again until the accurate jet flow key parameter is determined.
More specifically, if the soil erosion displacement of the time-displacement curve in the jet flow direction in (6) does not reach the burying depth of the directly-buried submarine cable 4, which indicates that the jet flow energy is small and the cleaning task of the directly-buried submarine cable 4 cannot be completed, the jet flow speed needs to be increased or the jet flow target distance needs to be reduced, i.e. the speed v of the nozzle outlet is increased 0 Or the target distance L of the water jet is reduced, so that the depth of the pit is increased, and the aim of cleaning is fulfilled; if the maximum damage width is smaller than the diameter of the directly-buried submarine cable 4, the cleaning task cannot be completed, the diameter d of the jet nozzle outlet needs to be increased, and the maximum damage width is enlarged; if the directly buried submarine cable 4 is damaged, which indicates that the jet energy is larger, the jet speed, the jet target distance or the jet diameter needs to be reduced, namely, the speed v of the nozzle outlet is reduced 0 Target distance of the water jet or nozzle outlet diameter d. According to the analysis of the simulation result, the jet flow key parameters are adjusted, the steps (3) to (6) are executed again until the jet flow soil erosion displacement exceeds the embedding depth of the directly-buried submarine cable 4, the maximum damage width is larger than the diameter of the directly-buried submarine cable 4, and the directly-buried submarine cable 4 is not damaged, so that the requirement of the directly-buried submarine cable for deprotection work can be met under the condition of the jet flow key parameters.
In the embodiment, the simulation result is analyzed, in 2000us, the jet flow soil erosion displacement, namely the erosion depth is 5cm, the maximum damage width is 0.5cm, the submarine cable is not damaged, the requirement of the direct-buried submarine cable for deprotection work is met, the jet flow key parameters do not need to be adjusted, and the determined jet flow key parameters are as follows: velocity v of the nozzle outlet 0 =33m/s, nozzle outlet diameter d =0.3cm, target distance L =1cm of the water jet.
(8) Guiding the selection of the jet flow equipment and the design of the parameters
Determining the velocity v of the nozzle outlet in the key parameters of the jet flow by adopting a bottom-up method and the step (7) 0 Determining the water pump lift of the jet flow equipment according to the jet flow speed; nozzle for spraying liquidThe diameter d of the outlet corresponds to the diameter of the jet flow, and the diameter of a nozzle of the jet flow equipment can be determined; the target distance L of the water jet corresponds to the jet target distance, and the method can be used for guiding the nozzle installation mode of the jet equipment. In addition, the emergent flow rate can be calculated according to the jet velocity and the jet diameter, so that the flow rate of the water pump can be determined, and the model selection design of the water pump of the jet equipment can be guided.
The preferred embodiments of the present invention have been described in detail with reference to the accompanying drawings and specific examples, however, the present invention is not limited to the specific details of the above embodiments, and various simple modifications may be made to the technical solution of the present invention within the technical idea of the present invention, and these simple modifications all belong to the protection scope of the present invention.
Claims (8)
1. A method for determining jet equipment for protecting work of a directly buried submarine cable is characterized by comprising the following steps:
step one, determining the soil physical characteristics of a soil body of a protective working section of a direct-buried submarine cable, comprising the following steps: specific gravity, density, water content, volume modulus, shear modulus, friction angle, cohesion force, critical failure pressure;
step two, according to the physical characteristics of the soil and the necessary conditions of the jet destruction of the soil body: the average acting force of the jet flow in the half-width range of the surface of the soil body is larger than the critical destruction pressure of the soil body, and the key parameters of the jet flow are preliminarily estimated, wherein the key parameters comprise: velocity v of the nozzle outlet 0 The diameter d of the nozzle outlet and the target distance L of the water jet;
thirdly, establishing a direct-buried submarine cable jet flow soil breaking model in ANSYS according to the preliminarily estimated jet flow key parameters, dividing grids, and exporting a K file;
modifying the K file in the LS _ PREPOST, and defining materials, boundary conditions, contact, load and control equations by using an ALE algorithm to obtain a modified K file;
step five, importing the corrected K file into LS _ DYAN to perform solving analysis to obtain a simulation model;
step six, carrying out post-processing on the simulation model in LS _ PREPOS to obtain a simulation result of the deprotection work of the directly-buried submarine cable;
step seven, analyzing the simulation result, if the requirement of the direct-buried submarine cable deprotection work is met, taking the jet key parameter preliminarily estimated in the step two as an accurate jet key parameter, if the requirement of the direct-buried submarine cable deprotection work is not met, adjusting the jet key parameter preliminarily estimated, and re-executing the step three to the step six until the accurate jet key parameter is determined;
step eight, determining parameters of the jet flow equipment according to the accurate key parameters of the jet flow, wherein the method comprises the following steps: the water pump lift, the jet diameter, the nozzle installation mode and the water pump model selection guide the jet equipment model selection and parameter design.
2. The method for determining the fluidic device for the direct sea cable deprotection work according to claim 1, wherein: in the step one, in the determination of the physical characteristics of the soil, the specific gravity is determined by a pycnometer method, the density is determined by a cutting ring method, the water content is determined by a drying method, and the shear modulus and the volume modulus are determined by a penetrometer and K 0 The consolidation test is used for measuring the friction angle and the cohesive force, the direct shear test is used for measuring the friction angle and the cohesive force, and the triaxial compression test is used for measuring the critical failure stress.
3. The method for determining the fluidic device for the direct sea cable deprotection work according to claim 2, wherein: in the second step, the average acting force of the jet flow in the half-width range of the soil surface
Comprises the following steps:
wherein v is 0 Is the velocity of the nozzle outlet, ρ is the density of the seawater, d is the nozzle outlet diameter, α is the water jet divergence angle of the nozzle, l 0 The length of the constant speed core of the water jet, L is the target distance of the water jet;
4. The method for determining the fluidic device for the unprotected working of the buried sea cable according to claim 3, wherein the method comprises the following steps: in the third step, in the establishment of the direct-buried submarine cable jet flow soil breaking model, firstly, the size of 1/2 jet flow model is preliminarily established, then 4 kinds of hollow materials are endowed by adopting an SOID _164 solid unit, the jet flow source (1) and the water area (2) share the joint, then, a soil body model and a submarine cable model are established, the soil body (3) and the direct-buried submarine cable (4) need to share the joint, and the model size is required to eliminate the boundary effect influence; in the grid division, the model is subjected to grid division, and the water area grid and the soil body grid near the jet flow damage are encrypted.
5. The method for determining the fluidic device for the unprotected work of the buried submarine cable according to claim 4, wherein: in the fourth step, the step of modifying the K file is as follows:
(1) definition of materials: in the soil material model, inputting the physical soil characteristics obtained in the step one into a keyword MAT _147_FHWA _SOILand an erosion algorithm MAT _ ADD _ ERODION, wherein the soil unit algorithm adopts SECTION _ SOILD, and the parameters are kept to be default; the key word of the material model of the directly-buried submarine cable (4) is MAT _ RIGID, and the key word comprises: density, young modulus and Poisson ratio, a unit algorithm of the direct-buried submarine cable (4) adopts SECTION _ SOILD, and parameters are kept to be default; the keywords of the model of the jet source (1) and the water area (2) are MAT _009 null, the state equation is defined as EOS _ GRUNERSEN, the cell algorithm of the water area (2) and the jet source (1) is set as a fixed value, and the rest are kept as default; endowing the parameters to a model, respectively defining ALE substances for the jet source (1) and the water area (2), wherein the keyword is ALE _ MULTIL _ MATERIAL _ GROUP, and adopting an ALE algorithm;
(2) defining the boundary conditions: the bottom of the soil body is subjected to full constraint, the normal direction of the symmetrical surface of the 1/2 jet model limits translation, and the other two directions limit rotation; applying NON-reflection BOUNDARY conditions to the side surfaces and the bottom ends of the soil body (3) and the water area (2) to simulate an infinite area in space, wherein the keyword is BOUNDARY _ NON _ refelction;
(3) defining the contact: the soil body (3) and the directly-buried submarine cable (4) are IN fluid-solid coupling with the jet source (1) and the water area (2) through keyword associated _ lag _ IN _ SOILD definition, the SLAVE plane SLAVE is a PART consisting of the soil body (3) and the directly-buried submarine cable (4), and the MASTER plane MASTER is a PART consisting of the jet source (1) and the water area (2);
(4) defining the load: the jet flow continuous jet is characterized in that fluid with vertical speed continuously appears at the outlet of a nozzle, and the jet flow source for continuous jet can be realized by setting a jet speed function curve and keywords such as BOUNDARY _ PRESCRIBED _ MOTION _ SET and associating the curve with the speed value of the jet flow fluid;
(5) defining a control equation: BULK VISCOSITY CONTROL _ BULK _ VISCOSITY, kept by default; ALE and Euler calculation sets global CONTROL parameters such as CONTROL _ ALE, and defaults are kept; controlling HOURGLASS _ HOURGLASS, keeping default; the calculation time, CONTROL _ TERMINATION, the time step, CONTROL _ time _ and the output frequency, DATABASE _ BINARY _ D3PLOT, are determined according to the requirements of the protection removal work of the direct-buried submarine cable.
6. The method for determining the jet flow device for the direct-buried submarine cable deprotection work according to any one of claims 1 to 5, wherein: in the sixth step, the simulation result of the deprotection work of the directly buried submarine cable comprises: (1) extracting time-displacement historical data of the soil unit, and drawing a time-displacement curve in the jet flow direction to obtain soil erosion displacement; (2) measuring the maximum failure width of the unit above the directly buried submarine cable (4); (3) and extracting historical data of unit stress and strain of the model direct-buried submarine cable (4) to store the historical data into a model stress-strain file, extracting the model stress-strain file from the Xyplot to draw a model stress-strain curve, and obtaining a comparison graph of the model stress-strain curve and an actual direct-buried submarine cable stress-strain curve.
7. The method for determining the fluidic device for the direct sea cable deprotection work according to claim 6, wherein: in the seventh step, the condition that the simulation result does not meet the requirements of the direct-buried submarine cable deprotection work and the preliminarily estimated jet flow key parameter needs to be adjusted includes: (1) when the soil erosion displacement of the time-displacement curve in the jet flow direction does not reach the burying depth of the direct-buried submarine cable (4), the velocity v of the nozzle outlet needs to be increased 0 Or reducing the target distance L of the water jet; (2) the maximum damage width of the unit above the direct-buried submarine cable (4) is smaller than the diameter of the direct-buried submarine cable (4), and the diameter d of the jet nozzle outlet needs to be increased; (3) in a comparison graph of a model stress-strain curve and an actual direct-buried submarine cable stress-strain curve, if the direct-buried submarine cable (4) in the model is damaged, the speed v of the outlet of the nozzle needs to be reduced 0 Target distance of the water jet or nozzle outlet diameter d.
8. The method for determining a fluidic device for the unprotected working of a buried sea cable according to claim 7, wherein: in the eighth step, the speed v of the nozzle outlet is determined 0 Determining the water pump lift of the jet flow equipment, determining the diameter of a nozzle of the jet flow equipment according to the diameter d of the outlet of the nozzle, and guiding the installation mode of the nozzle of the jet flow equipment according to the target distance L of water jet flow; the flow of the emergent flow can be calculated according to the jet speed and the jet diameter, so that the flow of the water pump can be determined, and the model selection design of the water pump of the jet equipment can be guided.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202211061847.1A CN115358085A (en) | 2022-09-01 | 2022-09-01 | Determination method for jet flow equipment for direct-buried submarine cable deprotection work |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202211061847.1A CN115358085A (en) | 2022-09-01 | 2022-09-01 | Determination method for jet flow equipment for direct-buried submarine cable deprotection work |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN115358085A true CN115358085A (en) | 2022-11-18 |
Family
ID=84005063
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202211061847.1A Pending CN115358085A (en) | 2022-09-01 | 2022-09-01 | Determination method for jet flow equipment for direct-buried submarine cable deprotection work |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN115358085A (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN117073979A (en) * | 2023-10-18 | 2023-11-17 | 中国电力工程顾问集团中南电力设计院有限公司 | Test device and method for cleaning underwater cable soil covering |
-
2022
- 2022-09-01 CN CN202211061847.1A patent/CN115358085A/en active Pending
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN117073979A (en) * | 2023-10-18 | 2023-11-17 | 中国电力工程顾问集团中南电力设计院有限公司 | Test device and method for cleaning underwater cable soil covering |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| CN112257140B (en) | Safety coefficient calculation method for seabed slope stability | |
| Chatterjee et al. | Numerical simulations of pipe–soil interaction during large lateral movements on clay | |
| CN105138731B (en) | A kind of decomposition of hydrate causes submarine slope unstability evaluation system and method | |
| CN103469780B (en) | A kind of computational methods of Gravity Dam Foundation stability against deep sliding critical slip surface | |
| CN106844859A (en) | A kind of Simulations of Water Waves Due To Landslides computational methods | |
| CN101261177A (en) | Active mode ocean platform mixing model test accomplishing method | |
| CN104252576B (en) | Inversion method for equivalent calculation parameters of subway tunnel rock-soil body | |
| CN115358085A (en) | Determination method for jet flow equipment for direct-buried submarine cable deprotection work | |
| Hung et al. | Volume change predictions in expansive soils using a two-dimensional finite element method | |
| CN108643246B (en) | The prediction technique that artesian water precipitation influences surrounding enviroment in foundation pit construction | |
| CN108842821A (en) | A kind of drilling and blasting method builds the calculation method of seabed tunnel Rational Depth | |
| Wang et al. | Undrained bearing capacity of suction caissons for offshore wind turbine foundations by numerical limit analysis | |
| CN111310319A (en) | Method for accurately predicting bearing capacity before and after liquefaction of marine pile foundation | |
| Wang et al. | Mechanical parameter inversion in sandstone diversion tunnel and stability analysis during operation period | |
| CN108661089B (en) | Numerical analysis method for ultimate expansion shear force of pile foundation in expansive land area | |
| Tang et al. | Bearing capacity reliability analysis using the coupled FEM-BPNN-RSM for monopile-supported OWTs | |
| Zhang et al. | Numerical investigation on horizontal deformation of large diameter monopile under cyclic wave loading with local scour holes | |
| Pike et al. | Continuum modelling of ice gouge events: Observations and assessment | |
| Wang et al. | Rigid dynamic performance simulation of an offshore pipeline plough | |
| CN110321569B (en) | Numerical simulation method suitable for influence of pile shoe plugging on adjacent pile foundation | |
| CN116776553A (en) | Method and device for controlling deformation of shield construction earth surface based on digital twin | |
| Yang et al. | Numerical modeling of seabed ice scour | |
| ZHANG et al. | Model tests of large-diameter single pile under horizontal cyclic loading in sand | |
| CN113177252B (en) | Dam body geomembrane three-dimensional stress deformation calculation method | |
| CN116975969B (en) | Method and system for real-time positioning and damage quantification of concrete dam crack expansion under explosive load |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PB01 | Publication | ||
| PB01 | Publication | ||
| SE01 | Entry into force of request for substantive examination | ||
| SE01 | Entry into force of request for substantive examination |