CN115980758A - Mud line position tester integrated in seabed in-situ equipment and identification method - Google Patents
Mud line position tester integrated in seabed in-situ equipment and identification method Download PDFInfo
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- CN115980758A CN115980758A CN202211619409.2A CN202211619409A CN115980758A CN 115980758 A CN115980758 A CN 115980758A CN 202211619409 A CN202211619409 A CN 202211619409A CN 115980758 A CN115980758 A CN 115980758A
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Abstract
The invention provides a mud line position tester integrated in seabed in-situ equipment and an identification method. The method solves the problem that the spatial position relation between the seabed in-situ equipment and the mud line cannot be determined under the influence of seabed surface sediment and equipment settlement coupling. Based on the acoustic inversion principle and the hydrostatic pressure calculation method, undisturbed observation is carried out, and disturbance of the interface monitoring method of the traditional contact type testing method on seabed surface sediment is avoided. The echo signal data and the pressure data are converted into sediment concentration data and water depth data, and the sediment concentration data and the water depth data are combined with a mud line space position tester to be installed at a specific position of the seabed in-situ equipment, so that the relation between the seabed in-situ equipment and the mud line space position can be accurately judged, and meanwhile, the settlement depth of the seabed in-situ equipment is accurately analyzed.
Description
Technical Field
The invention relates to the technical field of submarine in-situ exploration and monitoring, in particular to a mud line position tester integrated on submarine in-situ equipment and an identification method.
Background
With the deepening of marine scientific research, resource and energy development and environmental protection, more and more engineering structures, in-situ equipment and the like need to be laid on surface sediments of the seabed and operated for a long time, such as deep sea observation nets, pipe cable systems, mining vehicles and the like. The design, construction and long-term operation of these structures are closely related to the physical and mechanical properties of the seabed surface sediments. Therefore, the physical and mechanical properties of the seabed surface sediment attract wide attention, the continuous development of the seabed surface sediment in-situ test technology is promoted, and the aim of detecting the mechanical parameters of the seabed surface sediment in the whole sea depth is achieved by the adoption of the 'Meiji' of the national key research and development plan project equipment of China oceanic university. However, the complex interaction process of the surface sediments at the seabed of different sea areas, the environmental water and the in-situ detection equipment causes the position relation between the bottom-sitting type seabed in-situ equipment and the mud line to be difficult to determine, and the data analysis based on the in-situ equipment is difficult.
For example, in the in situ testing of the strength of surface sediments on the seabed, a mud line is generally used as an upper interface of the surface sediments on the seabed, and an environmental water body is arranged above the mud line and belongs to Newtonian fluid. Below the mudline is a mixture of water and sediment (McKee et al, 2004), defined as surface sediment on the seabed, with the mechanical behaviour of non-newtonian fluids (Nian et al, 2019, zhang et al, 2021). In the conventional submarine in-situ test, because the strength of the submarine surface sediment below the mud line is very low, submarine in-situ equipment is likely to sink into deeper sediment, so that the spatial position of the test device and the mud line is difficult to determine (even the phenomenon that the initial position of the test probe is below the mud line may occur), and further, in-situ test data cannot accurately reflect the strength parameters and the corresponding positions of the submarine surface sediment. Even if a high-precision probe (static cone penetration and full-flow penetration) for acquiring data in real time is adopted, in the process that the probe penetrates into the seabed surface sediment, the low-strength characteristic of the seabed surface sediment causes that the judgment of when the probe contacts a mud line through in-situ test data is still very difficult.
Furthermore, in practical engineering applications, most subsea in situ equipment needs to be placed on the seabed. When the seabed in-situ equipment falls to the seabed, supporting legs of the seabed in-situ equipment are inevitably embedded into seabed surface sediments to a certain depth under many conditions according to geological survey experience of ocean engineering, but the sinking depth is difficult to obtain and evaluate under the current conditions. It is therefore difficult to determine if the observation (or detection) instrument carrying the subsea in situ equipment is above the mudline, when it comes into contact with the mudline. More importantly, the surface sediment of the sea bottom close to the mud line is the most concerned part for ocean observation and engineering construction.
The existing identification method is mainly based on a sensor for penetrating sediment to identify a mud line, for example, a device and a method for measuring the position of a seawater-sediment interface and mechanical characteristics in situ disclosed by a patent (application number: 201810114193.1), and a pore pressure observation device and a working method for identifying a seabed interface based on a natural potential method disclosed by a patent (application number: 202110814070.0) respectively use a mechanical property testing probe and an electrical property testing probe to distinguish the interfaces in a penetration mode. These adopt the contact test method, not only need insert one or more probe rod more, cause the cost to rise by a wide margin, and the probe rod of inserting more can disturb the deposit all around, influences the test of penetrating device. More importantly, in the process of penetrating the probe rod, the equipment carrying the probe rod is likely to be displaced, so that the penetration device and the spatial position testing device need to be ensured to work synchronously.
Disclosure of Invention
In order to make up for the defects of the prior art, the invention provides a mud line position tester integrated in seabed in-situ equipment and an identification method, wherein the tester comprises an acoustic transducer and a pressure sensor, the method comprises water pressure data water depth data inversion, suspended sediment concentration acoustic inversion, accurate identification of the mud line position and equipment settlement calculation, and accurate judgment of the mud line space position under the settlement state of most seabed in-situ equipment can be realized.
The invention is realized by the following technical scheme: a mud line position tester integrated in seabed in-situ equipment and an identification method are disclosed, the mud line position tester integrated in the seabed in-situ equipment comprises a pressure-resistant shell with a fixing device, a connecting channel arranged in the pressure-resistant shell, an acquisition and storage control unit, a battery, a connecting pipe, a pressure sensor and an acoustic transducer positioned at the lower end of the pressure-resistant shell, wherein the fixing device is fixedly arranged at the upper part of the pressure-resistant shell, one end of the fixing device is connected with the tester, the other end of the fixing device is connected with the bottom-sitting type seabed in-situ equipment, the acquisition and storage control unit is connected with the pressure sensor through a data line, and the data line extends to the acoustic transducer through the connecting channel; the pressure sensor collects the water pressure of the pressure at the top of the tester in real time through the connecting pipe; the acoustic transducer is positioned at the lower part of the tester, and the tester is set by the acquisition, storage and control unit to transmit acoustic signals with specific thickness and layer position to a section within a water depth range below an installation position; the battery is positioned between the pressure sensor and the acoustic transducer and supplies power to the pressure sensor, the acoustic transducer and the acquisition storage control unit through wires;
the identification method of the mud line position tester integrated on the seabed in-situ equipment specifically comprises the following steps:
step 1: according to regional sea state and geological information investigation, determining the substrate condition of the distribution position of the instrument;
and 2, step: calibrating the pressure sensor, arranging a device for observing time, collecting frequency and acoustic layering thickness h, and determining the cable, the laying ship, the laying date and the station longitude and latitude
；
And step 3: fixing the tester on the framework of the sitting-bottom type seabed in-situ equipment by using a fixing device, wherein no shielding object is arranged below the tester, and recording the height H from the mounting position to the supporting leg, wherein the height H is the observation range of the acoustic signal of the tester;
and 4, step 4: placing the water to a designated place for testing, and recovering the effluent after all observations are finished; the device is disassembled, maintained and stored on land, data in the acquisition and storage control unit is read, real-time water depth is obtained, and correction of echo signals is completed;
and 5: and (4) performing an indoor instrument calibration experiment, enabling actual in-situ test data to correspond, and giving a space corresponding position of the mud line and the equipment settlement distance.
Preferably, step 4 specifically comprises the following steps:
step 4.1: processing the water pressure data obtained in situ, averaging the water pressure data observed by the pressure sensor in real time with ten minutes as a segment period to obtain average water pressure
Based on the hydrostatic pressure calculation method formula (1) will
Is converted into water depth data of the observation equipment,
wherein, the first and the second end of the pipe are connected with each other,
the depth of water m for the instrument installation position; />
The density of seawater is kg.m < -3 >; />
Is the acceleration of gravity, m.s-2; />
Is the average water pressure, pa;
and 4.2: latitude and longitude of laying position combined with instrument
And the installed depth of water of the instrument>
Obtaining the spatial position ^ of the marine bottom-standing in-situ test apparatus>
。
Step 4.3: using formula (2) to convert the original echo signal
Corrected for backscatter intensity reflecting the concentration of suspended sand in the body of water>
；/>
Wherein, the first and the second end of the pipe are connected with each other,
as to the intensity of the back-scattering,dB；/>
=0.4 is the received signal unit conversion factor, dB · count-1; />
Is the echo strength, count, received by the instrument; />
Is the system noise, dB; />
Is the distance from the acoustic transducer to the observation location, calculated from the layered thickness, m; />
Is the absorption coefficient, obtained by the nature of the deposit in step 1, dB · m-1; c is a constant associated with the transducer including errors due to transmit pulses, transmit power performance parameters, etc., calculated by the transducer performance index, dB.
According to the preferable scheme, the fixing device comprises screws, fixing buckles and fixing rods, the four fixing rods are evenly distributed on the upper portion of the pressure-resistant shell, mounting holes are formed in the fixing rods, the screws penetrate through the mounting holes to fix the tester on the fixing buckles, one ends of the fixing buckles are connected with the tester, and the other ends of the fixing buckles are connected with the bottom-sitting type seabed in-situ equipment to fix the tester.
Preferably, step 5 specifically comprises the following steps:
step 5.1: the indoor calibration test is carried out by using the bottom materials which are the same as the observation positions, the mud line identification device is fixed above the calibration barrel, so that the instrument is opened, and the suction filtration test is carried out on water samples at different positions to obtain the suspended sediment concentration
；
Step 5.2: pumping filtration test data of collected water sample
Fitting the corrected backscatter intensity of the corresponding position according to formula (3) to determine a fitting coefficient->
；
Wherein the content of the first and second substances,
the concentration of suspended silt is kg.m < -3 >; />
Is the backscatter intensity, dB; />
Is->
Fitting the obtained parameters;
step 5.3: substituting the fitting coefficient into the formula (3) to obtain the concentration of the suspended sediment
Backscatter intensity->
The concentration of the suspended sediment in the range of the observation profile H below the tester is further obtained;
step 5.4: calculating the concentration gradient of the suspended sediment concentration by taking the layering height h as an independent variable and the layering concentration as a dependent variable; the gradient calculation may be based on the gradient function of Matlab;
step 5.5: based on the difference of suspended sediment concentration in the environmental water body and under the mud line, searching the height position where the maximum gradient value is located from top to bottom, namely the mud line position H1;
step 5.6: the settling depth H2= H-H1 can be determined according to the installation position of the tester on the bottom-seated equipment.
Due to the adoption of the technical scheme, compared with the prior art, the invention has the following beneficial effects:
(1) The invention provides a mud line space position tester integrated on seabed in-situ equipment. The method solves the problem that the spatial position relation between the seabed in-situ equipment and a mud line cannot be determined under the influence of seabed surface sediment and equipment settlement coupling.
(2) The mud line space position tester provided by the invention has the advantages of small volume, easiness in installation, low power consumption, strong identification capability and the like, and can be used on most of seabed in-situ equipment through the fixing device, so that synchronous observation with the seabed in-situ equipment is realized.
(3) The invention is based on the acoustic principle, carries out undisturbed observation, avoids the disturbance of the interface monitoring method of the traditional contact type test method to the sediment on the surface layer of the seabed, and ensures the accuracy of in-situ test data.
(4) The invention is based on an acoustic inversion principle and a hydrostatic pressure calculation method, converts echo signal data and pressure data into sediment concentration data and water depth data, is installed at a specific position of a seabed in-situ device by combining a mud line space position tester, can accurately judge the relation between the seabed in-situ device and the mud line space position, and simultaneously accurately analyzes the settlement depth of the seabed in-situ device.
Additional aspects and advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention.
Drawings
The above and/or additional aspects and advantages of the present invention will become apparent and readily appreciated from the following description of the embodiments, taken in conjunction with the accompanying drawings of which:
FIG. 1 is a schematic view of an apparatus;
FIG. 2 is a schematic view of an instrument installation position and an observation range;
FIG. 3 is a schematic view of the location identification of the mudline;
wherein, the corresponding relationship between the reference numbers and the components in fig. 1 to 3 is:
the device comprises a fixing device 1, an acquisition and storage control unit 2, a connecting channel 3, an acoustic transducer 4, a connecting pipe 5, a pressure sensor 6, a battery 7 and a pressure-resistant shell 8.
Detailed Description
In order that the above objects, features and advantages of the present invention can be more clearly understood, a more particular description of the invention, taken in conjunction with the accompanying drawings and detailed description, is set forth below. It should be noted that the embodiments and features of the embodiments of the present application may be combined with each other without conflict.
In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present invention, however, the present invention may be practiced otherwise than as specifically described herein, and thus the scope of the present invention is not limited by the specific embodiments disclosed below.
The mud line position tester integrated in the subsea in-situ equipment and the identification method according to the embodiment of the present invention will be described in detail with reference to fig. 1 to 3.
As shown in figure 1, the invention provides a mud line position tester integrated in a seabed in-situ device and an identification method, the mud line position tester integrated in the seabed in-situ device comprises a pressure-resistant shell 8 with a fixing device 1, a connecting channel 3 arranged in the pressure-resistant shell 8, an acquisition and storage control unit 2, a battery 7, a connecting pipe 5, a pressure sensor 6 and an acoustic transducer 4 positioned at the lower end of the pressure-resistant shell 8, wherein the fixing device 1 comprises screws, fixing buckles and fixing rods, the four fixing rods are evenly distributed on the upper part of the pressure-resistant shell 8, the fixing rods are provided with mounting holes, the screws penetrate through the mounting holes to fix the tester on the fixing buckles, one ends of the fixing buckles are connected with the tester, and the other ends of the fixing buckles are connected with the seabed in-situ device in a sitting manner, so that the tester is fixed. The acquisition, storage and control unit 2 is connected with the pressure sensor 6 through a data line, and the data line extends to the acoustic transducer 4 through the connecting channel 3, so that the acquisition, storage and control unit 2 can set, adjust and store the sensor test parameters; the pressure sensor 6 collects the water pressure of the pressure at the top of the tester in real time through the connecting pipe 5; the acoustic transducer 4 is positioned at the lower part of the tester, the tester is set through the acquisition, storage and control unit 2 to transmit acoustic signals with specific thickness and layer to a section within a water depth range below an installation position, each sampling depth interval can be set, and signals reflected by silt or other suspended particles in a depth section are received; the battery 7 is positioned between the pressure sensor 6 and the acoustic transducer 4 and supplies power to the pressure sensor 6, the acoustic transducer 4 and the acquisition storage control unit 2 through electric wires;
the identification method of the mud line position tester integrated on the seabed in-situ equipment specifically comprises the following steps:
step 1: according to regional sea state and geological information investigation, determining the substrate condition of the distribution position of the instrument;
step 2: the pressure sensor is revised according to the national standard (GB/T12763.10-2007), and the observation time, the acquisition frequency and the acoustic layering thickness of the device are sethDetermining the latitude and longitude of the cable, the laying ship, the laying date and the station
；
And step 3: the tester is fixed on the framework of the sitting-bottom type seabed in-situ equipment by using the fixing device 1, and no shielding object is arranged below the tester, so that the propagation of acoustic signals can not be shielded, and the normal use of other carried observation instruments is not influenced; recording the height of the mounting position from the supporting footH，HNamely the observation range of the acoustic signal of the tester; the relevant position of the instrument is shown in figure 2.
And 4, step 4: placing the water to a designated place for testing, and recovering the effluent after all observations are finished; the device is disassembled, maintained and stored on the land, the data in the acquisition and storage control unit 2 is read, the real-time water depth is obtained, and the correction of echo signals is completed; the method specifically comprises the following steps:
step 4.1: processing the water pressure data obtained in situ, averaging the water pressure data observed by the pressure sensor 6 in real time with ten minutes as a segment period to obtain average water pressure
To remove the water pressure change caused by high frequency factor; will based on hydrostatic pressure calculation method equation (1)>
Is converted into water depth data of the observation equipment,
wherein, the first and the second end of the pipe are connected with each other,
the depth of water m for the instrument installation position; />
Is the density of seawater, kg.m -3 ；/>
Is the acceleration of gravity, m.s -2 ；/>
Is the average water pressure, pa;
step 4.2: latitude and longitude of distribution position combined with instrument
And the installed depth of water of the instrument>
Obtaining the spatial position ^ of the marine bottom-standing in-situ test apparatus>
。
Step 4.3: the echo signal obtained by the acoustic transducer 4 is distorted due to the influence of noise and the propagation attenuation of the signal, and cannot be used directly, using the formula (2)The original echo signal is processed
Corrected for backscatter intensity reflecting the concentration of suspended sand in the body of water>
；
Wherein the content of the first and second substances,
is the backscatter intensity, dB; />
=0.4 is the conversion factor of the received signal unit, dB · count -1 ；/>
Is the echo strength, count, received by the instrument; />
Is the system noise, dB; />
Is the distance from the acoustic transducer 4 to the observation location, calculated from the layered thickness, m; />
Is the absorption coefficient, obtained by the nature of the deposit in step 1, dB m -1 ；CIs a constant related to the transducer, including errors caused by factors such as the transmission pulse, the transmission power performance parameters and the like, and is calculated by the transducer performance index, dB.
And 5: and (4) performing an indoor instrument calibration experiment, enabling actual in-situ test data to correspond, giving a space corresponding position of the mud line and the equipment settlement distance, and guiding engineering design and scientific research. The method specifically comprises the following steps:
step 5.1: the indoor calibration test is carried out by using the bottom materials which are the same as the observation positions, the mud line identification device is fixed above the calibration barrel, so that the instrument is opened, and the suction filtration test is carried out on water samples at different positions to obtain the suspended sediment concentration
；
Step 5.2: pumping filtration test data of collected water sample
Fitting the corrected backscatter intensity of the corresponding position according to formula (3) to determine a fitting coefficient->
；
Wherein the content of the first and second substances,
in order to suspend the concentration of silt, kg m -3 ；/>
Is the backscatter intensity, dB; />
Is->
Fitting the obtained parameters;
step 5.3: substituting the fitting coefficient into the formula (3) to obtain the concentration of the suspended sediment
Backscatter intensity->
To obtain the observation profile below the testerHSuspended sediment concentration within the range; />
Step 5.4: by the height of the layers of the suspended sediment concentrationhCalculating the concentration gradient by taking the independent variable and the layered concentration as dependent variables; the gradient calculation may be based on the gradient function of Matlab;
and step 5.5: based on the difference of suspended sediment concentration in the environmental water body and under the mud line, the height position where the maximum gradient value is located is searched from top to bottom and is the mud line positionH 1 As in fig. 3;
step 5.6: the settlement depth can be determined according to the installation position of the tester on the bottom-seated equipmentH 2 =H–H 1 。
In the description of the present invention, the terms "plurality" or "a plurality" refer to two or more, and unless otherwise specifically limited, the terms "upper", "lower", and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the drawings, and are merely for convenience in describing the present invention and simplifying the description, but do not indicate or imply that the referred device or element must have a specific orientation, be constructed in a specific orientation, and be operated, and thus should not be construed as limiting the present invention; the terms "connected," "mounted," "secured," and the like are to be construed broadly and include, for example, fixed connections, removable connections, or integral connections; may be directly connected or indirectly connected through an intermediate. The specific meanings of the above terms in the present invention can be understood by those skilled in the art according to specific situations.
In the description herein, the description of the terms "one embodiment," "some embodiments," "specific embodiments," etc., means that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the invention. In this specification, the schematic representations of the terms used above do not necessarily refer to the same embodiment or example. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.
The present invention has been described in terms of the preferred embodiment, and it is not intended to be limited to the embodiment. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.
Claims (4)
1. A mud line position tester integrated with seabed in-situ equipment and an identification method are disclosed, the mud line position tester integrated with seabed in-situ equipment comprises a pressure-resistant shell (8) with a fixing device (1), a connecting channel (3) arranged inside the pressure-resistant shell (8), an acquisition and storage control unit (2), a battery (7), a connecting pipe (5), a pressure sensor (6) and an acoustic transducer (4) positioned at the lower end of the pressure-resistant shell (8), and is characterized in that the fixing device (1) is fixedly arranged at the upper part of the pressure-resistant shell (8), one end of the fixing device is connected with the tester, the other end of the fixing device is connected with the seabed in-situ equipment in a sitting bottom manner, the acquisition and storage control unit (2) is connected with the pressure sensor (6) through a data line, and the data line extends to the acoustic transducer (4) through the connecting channel (3); the pressure sensor (6) collects the water pressure of the pressure at the top of the tester in real time through the connecting pipe (5); the acoustic transducer (4) is positioned at the lower part of the tester, and the tester is set to transmit acoustic signals with specific thickness and horizon to a section within a water depth range below an installation position through the acquisition, storage and control unit (2); the battery (7) is positioned between the pressure sensor (6) and the acoustic transducer (4), and supplies power to the pressure sensor (6), the acoustic transducer (4) and the acquisition storage control unit (2) through electric wires;
the identification method of the mud line position tester integrated on the seabed in-situ equipment specifically comprises the following steps:
step 1: according to regional sea state and geological information investigation, determining the substrate condition of the distribution position of the instrument;
step 2: to pressureSensor calibration, and setting observation time, acquisition frequency and acoustic layering thickness of the devicehDetermining the latitude and longitude of the cable, the laying ship, the laying date and the station
；
And step 3: fixing the tester on the framework of the bottom-sitting type seabed in-situ equipment by using a fixing device (1), recording the height between the installation position and the supporting leg without a shielding object below the testerH，HNamely the observation range of the acoustic signal of the tester;
and 4, step 4: placing the water to a designated place for testing, and recovering the effluent after all observations are finished; the device is disassembled, maintained and stored on the land, the data in the acquisition and storage control unit (2) is read, the real-time water depth is obtained, and the correction of echo signals is completed;
and 5: and (4) performing an indoor instrument calibration experiment, enabling actual in-situ test data to correspond, and giving a space corresponding position of the mud line and the equipment settlement distance.
2. The mud line position tester and identification method integrated on the seabed in-situ equipment as claimed in claim 1, wherein the step 4 comprises the following steps:
step 4.1: the water pressure data obtained in situ is processed, and the water pressure data observed by the pressure sensor (6) in real time is averaged by taking ten minutes as a segment period to obtain the average water pressure
Based on the hydrostatic pressure calculation method formula (1) will
Is converted into water depth data of the observation equipment,
wherein the content of the first and second substances,
the depth of water m for the instrument installation position; />
Is the density of seawater, kg.m -3 ；/>
Is the acceleration of gravity, m.s -2 ；/>
Is the average water pressure, pa;
step 4.2: latitude and longitude of laying position combined with instrument
And the installed depth of water of the instrument>
Obtaining a spatial position ^ of a marine sitting bottom in situ test apparatus>
；
Step 4.3: the original echo signal is processed using equation (2)
Backscatter intensity corrected to reflect water hang-sand concentration>
；
Wherein the content of the first and second substances,
is the backscatter intensity, dB; />
=0.4 is the conversion factor of the received signal unit, dB · count -1 ；/>
Is the echo strength, count, received by the instrument; />
Is the system noise, dB; />
Is the distance from the acoustic transducer (4) to the observation location, calculated from the layered thickness, m; />
Is the absorption coefficient, obtained by the nature of the deposit in step 1, dB m -1 ；CIs a constant related to the transducer, including errors caused by factors such as transmitted pulses, transmitted power performance parameters, and the like, and is calculated by the transducer performance index, dB.
3. The mud line position tester and the identification method integrated in the seabed in-situ equipment as claimed in claim 1, wherein the fixing device (1) comprises screws, fixing buckles and fixing rods, the four fixing rods are evenly distributed on the upper part of the pressure-resistant shell (8), the fixing rods are provided with mounting holes, the screws penetrate through the mounting holes to fix the tester on the fixing buckles, one ends of the fixing buckles are connected with the tester, and the other ends of the fixing buckles are connected with the seabed in-situ equipment, so that the tester is fixed.
4. The mud line position tester and identification method integrated on the seabed in-situ equipment as claimed in claim 1, wherein the step 5 comprises the following steps:
step 5.1: the indoor calibration test is carried out by using the bottom materials which are the same as the observation positions, the mud line identification device is fixed above the calibration barrel, so that the instrument is opened, and the suction filtration test is carried out on water samples at different positions to obtain the suspended sediment concentration
；
And step 5.2: pumping filtration test data of collected water sample
Fitting the corrected backscatter intensity of the corresponding position according to formula (3) to determine a fitting coefficient->
；
Wherein the content of the first and second substances,
in order to suspend the concentration of silt, kg.m -3 ；/>
Is the backscatter intensity, dB; />
Is->
Fitting the obtained parameters;
step 5.3: substituting the fitting coefficient into the formula (3) to obtain the concentration of the suspended sediment
Backscatter intensity>
To obtain the observation profile below the testerHSuspended silt concentration within the range;
step 5.4: by layered height of suspended silt concentrationhCalculating the concentration gradient by taking the independent variable and the layered concentration as dependent variables; the gradient calculation may be based on the gradient function of Matlab;
step 5.5: based on the difference of suspended sediment concentration in the environmental water body and under the mud line, the height position where the maximum gradient value is located is searched from top to bottom and is the mud line positionH 1 ；
Step 5.6: the settlement depth can be determined according to the installation position of the tester on the bottom-seated equipmentH 2 =H–H 1 。
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN116520431A (en) * | 2023-07-03 | 2023-08-01 | 自然资源部第一海洋研究所 | Method, device and medium for constructing broadband layered sound velocity structure of shallow seabed sediment |
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN116520431A (en) * | 2023-07-03 | 2023-08-01 | 自然资源部第一海洋研究所 | Method, device and medium for constructing broadband layered sound velocity structure of shallow seabed sediment |
| CN116520431B (en) * | 2023-07-03 | 2023-09-26 | 自然资源部第一海洋研究所 | Method, device and medium for constructing broadband layered sound velocity structure of shallow seabed sediment |
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