In-situ acoustic parameter calculation method for detecting device incompletely penetrating into sedimentary layer

Abstract

The invention discloses an in-situ acoustic parameter calculation method for a detection device incompletely penetrating into a sedimentary layer, and belongs to the field of marine acoustic characteristic detection. Comprising the steps that after consistency calibration is conducted on sedimentary layer sound wave data according to an underwater reference sound field, corresponding envelope curves are obtained through envelope fitting, and travel time and amplitude of a sedimentary layer sound field are further obtained; calculating to obtain travel time corresponding to each receiving point of the detection device, connecting lines according to the sequence of the receiving points to obtain travel time curves under different scanning sound velocities, and performing least square matching on the travel time curves and the travel time of the sound field of the sedimentary layer to obtain the sound velocity of the sedimentary layer; calculating to obtain the amplitude corresponding to each receiving point, and connecting according to the sequence of the receiving points to obtain an amplitude curve under different scanning sound attenuation; and performing least square matching on all the amplitude curves and the sound field amplitude of the sedimentary layer to obtain the attenuation coefficient of the sedimentary layer. The method disclosed by the invention effectively makes up the blank of related research when the measurement condition that the stratum is hard or the detection device is incompletely penetrated is encountered in the actual construction process.

Description

Technical Field

[0001] This invention belongs to the field of marine acoustic property detection, specifically relating to an in-situ acoustic parameter calculation method for a detection device that has not fully penetrated the sediment layer. Technical Background In-situ acoustic detection on the seabed is an important means of obtaining the acoustic characteristics of seabed sediments. By picking up the travel time and amplitude of the sound source signal at different channels, the velocity and attenuation law of the wavelet in the sediment layer can be accurately calculated. Existing technologies have carried out a lot of research on in-situ measurement devices and acoustic characteristic calculation methods for the acoustic characteristics of seabed sediments.

[0002] In in-situ measurements of the acoustic properties of seafloor sediments, the accuracy of P-wave first arrival and amplitude pickup directly determines the reliability of the calculated results. Traditional first arrival pickup methods suffer from low accuracy due to the relatively low initial amplitude of the wavelet and the low signal-to-noise ratio. Furthermore, the wavelet exhibits directional characteristics, significantly interfering with first arrival pickup and amplitude statistics. To address these issues, existing research has employed a consistency calibration method to resolve the interference from wavelet directionality, providing an effective solution for accurately assessing the acoustic properties of sedimentary layers.

[0003] However, existing studies use peak-point (single-point) travel time and amplitude calculations, which are susceptible to residual noise interference, reducing the reliability and stability of the sound velocity and attenuation factor calculation structures. Furthermore, this method relies on the probe fully penetrating the sedimentary layer. However, in actual data acquisition, situations such as hard formations or insufficient penetration speed can prevent the probe from fully penetrating the formation. In such cases, the acoustic signal propagation path differs from when fully penetrated; the sound field signal first propagates in the water, then penetrates the seawater-soil interface and into the formation, where it is recorded by the receiving transducer. Figure 1 (The purple line represents the interface between the sediment layer and seawater; the upper part is seawater, and the lower part is the sediment layer. The green line represents the propagation path, and the blue line is a schematic diagram of the detection device.) As shown, when the sound speed in the water and the sound speed in the sediment layer change, the sound field propagation path will also change accordingly. Therefore, it is evident that when penetration is incomplete, in addition to the inconsistent sound signal propagation paths, energy loss due to reflection occurs at the seawater-soil interface. When calculating the acoustic characteristics of the sediment, both the change in the sound field propagation path and the loss of reflection amplitude must be considered. Summary of the Invention

[0004] To address the aforementioned issues, this invention proposes an in-situ acoustic parameter calculation method for a detection device that has not fully penetrated the sedimentary layer.

[0005] The detection device comprises a transmitting point and multiple receiving points. The m receiving points located in the water are defined as the first receiving points, and the n receiving points located in the sediment layer are defined as the second receiving points, where m ≥ 0 and n ≥ 1. The method includes the following steps: S1, perform consistency calibration on the collected acoustic data of the seabed sediment layer based on the underwater reference acoustic field to obtain the calibrated sediment layer acoustic field; the underwater reference acoustic field is calculated using measured underwater acoustic data; S2, envelope fitting is performed on the reference sound field in water and the calibrated sound field of the sediment layer to obtain the envelope curve in water and the envelope curve of the sediment layer; S3, based on the envelope curve in water and the envelope curve of the sedimentary layer, the travel time and amplitude of the acoustic field of the sedimentary layer are obtained; S4. For the first receiving point, the corresponding travel time is obtained by dividing the distance between the transmitting point and the first receiving point by the speed of sound in water. The line connecting the transmitting point and the first receiving point is the first propagation path. For the second receiving point, all refraction points within the scanning speed range are obtained by using Snell's law and the sound speed scanning method. The travel time is further calculated based on the first propagation path corresponding to the refraction points. S5, connect the fixed travel time corresponding to the first receiving point with the travel time corresponding to the second receiving point under the same scanning sound speed in the order of the receiving points to obtain the travel time curves under different scanning sound speeds; perform least squares matching of all travel time curves with the travel time of the sedimentation layer sound field to obtain the corresponding square error value, and the scanning sound speed corresponding to the least square error value is the sound speed of the sedimentation layer. S6, based on the sound velocity of the sedimentary layer, select the second propagation path at the sound velocity of the sedimentary layer from all the first propagation paths in S4; S7, for the first receiving point, the corresponding amplitude is calculated by multiplying the set transmission amplitude by the geometric diffusion coefficient; for the second receiving point, the amplitudes corresponding to each second propagation path within the sound attenuation range are calculated using the sound attenuation scanning method. S8. Connect the fixed amplitude corresponding to the first receiving point and the amplitude corresponding to the second receiving point under the same sound attenuation according to the receiving point order to obtain the amplitude curves corresponding to different sound attenuations. Perform least squares matching of all amplitude curves with the sound field amplitude of the sedimentation layer to obtain the corresponding square error value. The sound attenuation corresponding to the least square error value is the sedimentation layer attenuation coefficient.

[0006] Furthermore, S1 specifically includes: S101, denoise the acoustic data collected in the water and seabed sedimentary layers to obtain the actual underwater acoustic field and the actual sedimentary layer acoustic field; S102 utilizes the acoustic properties of water to establish an underwater reference acoustic field based on a zero-phase bandwidth wavelet. S103, Solve for the matched filter between the actual underwater sound field and the underwater reference sound field; S104 applies the matched filter to the actual deposition layer acoustic field and calculates the calibrated deposition layer acoustic field.

[0007] Furthermore, in S4, the method for obtaining the refraction point corresponding to the second receiving point and the first propagation path includes: Within a predefined range of scanning sound speed, the detection device traverses all contact points on the interface between the sediment layer and the seawater at a predefined sound speed step size, obtaining all propagation paths formed by the contact points and the transmitting and receiving points of the detection device, as well as the corresponding incident and emission angles. According to Snell's law, contact points that meet the requirements are selected. If the incident angle and emission angle corresponding to the contact point satisfy Snell's law, the contact point is determined to be a refraction point, and the corresponding propagation path is retained as the first propagation path. Otherwise, the contact point and the corresponding propagation path are deleted.

[0008] Furthermore, S3 specifically includes: S301, the travel time difference between the underwater envelope curve and the sedimentary layer envelope curve is calculated using the cross-correlation method; S302, extract the peak travel time of the reference sound field in the water in S1, and add the peak travel time to the travel time difference to obtain the travel time of the sound field in the sediment layer; S303, extract the main envelope of the sediment layer envelope curve, and calculate the average value of the main envelope as the acoustic field amplitude of the sediment layer.

[0009] Furthermore, in S7, the value of the geometric diffusion coefficient is calculated by dividing 1 by the distance of the second propagation path corresponding to the first receiving point.

[0010] Furthermore, the travel time corresponding to the second receiving point is obtained by adding the travel time in water to the travel time in the sediment layer; the travel time in water is obtained by dividing the distance between the transmitting point and the refraction point by the speed of sound in water; the travel time in the sediment layer is obtained by dividing the distance between the refraction point and the second receiving point by the current scanning speed of sound.

[0011] Furthermore, for the second receiving point, the first propagation path corresponding to the refraction point is a broken line that starts from the transmitting point of the detection device, passes through the refraction point, and finally reaches the receiving point of the detection device.

[0012] Furthermore, the sound attenuation scanning method refers to sequentially traversing all the second propagation paths corresponding to the second receiving point in S6, traversing the given sound attenuation range with a certain step size, and obtaining the amplitude of the second propagation path corresponding to each second receiving point under the corresponding sound attenuation.

[0013] Furthermore, given the sound attenuation, the formula for calculating the amplitude is: ; in, For amplitude, Given the current sound attenuation, For the set launch amplitude, For sound attenuation in water, , These represent the propagation distances of the signal in the water and sediment layer, respectively, in the second propagation path. denoted as amplitude transmission coefficient, and G as geometric diffusion coefficient.

[0014] Furthermore, the formula for calculating the amplitude transmission coefficient is as follows: ; in, , The densities of water and sediment layers are respectively. , These are the angle of incidence and the angle of refraction, respectively. The speed of sound in water, The velocity of sound in the sediment layer.

[0015] The beneficial effects of this invention are: (1) The first arrival and amplitude of the longitudinal wave are picked up using the envelope cross-correlation method. This method benefits from the increase of the data (samples) involved in the calculation, and the calculation results are less affected by external interference such as residual noise, so the calculation results are more stable. (2) A measurement method was proposed for situations where the detection device does not fully penetrate when encountering hard strata or insufficient penetration speed during actual construction, thus filling a technological gap in this field. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of the sound field propagation path.

[0017] Figure 2 This is a schematic diagram of the process of the present invention.

[0018] Figure 3 Acoustic field map of the sedimentary layer after consistency calibration.

[0019] Figure 4 The image shows the reference acoustic field in the water and the calibrated acoustic field envelope of the sediment layer.

[0020] Figure 5 This is a cross-correlation time difference plot of the reference acoustic field envelope in water and the calibrated acoustic field envelope of the sediment layer.

[0021] Figure 6 This is a travel time graph for a given range of scanning sound speeds.

[0022] Figure 7 This is a graph showing the least-squares matching results between all traveltime curves and sediment layer traveltimes within a given scan velocity range.

[0023] Figure 8 This is a schematic diagram of the propagation path of sound velocity in the sedimentary layer.

[0024] Figure 9 This is an amplitude curve within a given scanning acoustic attenuation range.

[0025] Figure 10 This is a graph showing the least-squares matching results between all amplitude curves and the amplitude of the sediment layer within a given scanning acoustic attenuation range. Detailed Implementation

[0026] To make the above-mentioned objects, features, and advantages of the present invention more apparent and understandable, the specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings. Many specific details are set forth in the following description to provide a thorough understanding of the present invention. However, the present invention can be practiced in many other ways different from those described herein, and those skilled in the art can make similar modifications without departing from the spirit of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below. Technical features in the various embodiments of the present invention can be combined accordingly without mutual conflict.

[0027] In-situ acoustic detection results under incomplete penetration state M The mathematical expression is as follows: (1) in, S, R, E, G and N These represent the transmitter system response, receiver system response, medium acoustic properties, observation system geometric diffusion, and ambient noise, respectively. These represent the sound velocity coefficient and the sound attenuation coefficient, respectively, which determine the waveform's travel time and amplitude attenuation; subscripts w Represents water, subscript s Represents a sedimentary layer.

[0028] This invention addresses the issue of in-situ detection devices not fully penetrating the mud, proposing a method for calculating acoustic parameters of sedimentary layers. The main process is as follows: Figure 2 As shown, the specific processing flow is as follows: S1 employs a consistency calibration method, establishing a reference sound field in water, determining the filter between the reference sound field and the actual sound field in water, and filtering the actual sediment layer sound field data.

[0029] The specific steps include: (1) Use bandpass filters or statistical denoising methods to denoise the data collected in water and sediment layers.

[0030] (2) Establish a reference sound field in water using the sound velocity and sound attenuation coefficient in water.

[0031] By utilizing the sound velocity and sound attenuation coefficient in water, combined with the observation system of the in-situ acoustic detection device, desired waveforms corresponding to different channel positions are constructed, thereby obtaining the reference sound field.

[0032] This invention establishes a reference sound field based on a zero-phase bandwidth wavelet. By transmitting a zero-phase bandwidth wavelet into the water, the travel time of different receiving channels is calculated using the underwater sound velocity and an observation system. Given an underwater attenuation factor, the amplitude of different receiving channels is calculated using the observation system. Based on the travel time and amplitude of each channel, the desired waveform of each receiving channel is determined, thus forming the reference sound field. Here, both the underwater sound velocity and the underwater attenuation factor can be obtained through actual measurements.

[0033] (3) Solve for the matched filter between the actual underwater sound field and the reference sound field. This matched filter is used to realize the zero-phase transformation and wavelet shaping of the underwater sound field.

[0034] The process of solving the matched filter is represented by the following formula:

[0035] in, The underwater reference sound field is constructed based on a zero-phase bandwidth wavelet, combined with an underwater observation system (geometric diffusion) and an underwater attenuation factor. F This is a matched filter used to convert measured data in water into a reference sound field. These are sound field data measured in water.

[0036] (4) Apply the matched filter to the acoustic field data of the deposition layer.

[0037] Applying matched filters to in-situ probe data corresponding to sediment layers In this way, in-situ detection results of the sedimentary layer after consistency calibration are obtained. This is the calibrated acoustic field of the deposition layer:

[0038] The final calibrated acoustic field of the deposition layer is as follows Figure 3 As shown, each channel corresponds to a matched filter, and the filter parameters of different channels do not affect each other.

[0039] S2 performs envelope fitting on the underwater reference acoustic field constructed during consistency calibration and the calibrated sedimentary acoustic field data.

[0040] In this step, based on formulas (2) and (3), the following steps are performed: and Perform envelope pickup, such as Figure 4The diagram shows the envelope diagrams of the underwater reference sound field (left) and the calibrated sedimentary layer sound field (right) in a specific embodiment of the present invention. The red lines correspond to the envelope fitting curves of the underwater reference sound field and the calibrated sedimentary layer sound field, respectively, while the blue lines correspond to the underwater reference sound field without envelope fitting and the calibrated sedimentary layer sound field, respectively.

[0041] S3, obtain the amplitude information (non-peak amplitude) of the acoustic field of the deposition layer based on the envelope.

[0042] The specific steps are as follows: (1) The travel time difference (non-peak travel time) between the envelope of the reference sound field in the water and the envelope of the sound field in the sediment layer is calculated using the cross-correlation method. For example... Figure 5 The image shows the envelope travel time difference between the reference acoustic field in the water and the calibrated acoustic field of the sediment layer. The red numbers represent the travel time difference for each channel.

[0043] (2) Extract the peak travel time of the reference sound field in water in S2, add the peak travel time of the reference sound field in water to the travel time difference as the travel time of the sedimentary sound field, and use it to fit the travel time curve in S5.

[0044] (3) Calculate the average value of the main envelope of the calibrated sedimentary acoustic field obtained in S2, and use it as the amplitude (non-peak amplitude) of the calibrated sedimentary acoustic field for fitting the amplitude curve in S6.

[0045] This method for extracting travel time and amplitude significantly increases the number of sample points compared to traditional methods, effectively improving the reliability and stability of first arrival travel time and amplitude acquisition.

[0046] S4 employs a velocity scanning method, which traverses all contact points on the interface between the sedimentary layer and the seawater within a given scanning sound velocity range at a certain step size. Based on Snell's law, contact points that meet the requirements are selected as refraction points, and the travel time curve corresponding to each refraction point is calculated.

[0047] Given a scanning sound velocity, the method for determining each travel time in the travel time curve is as follows: First, scan all contact points on the interface between the sediment layer and the seawater, and the launch point of the detection device. and receiving point (In this specific embodiment, the transmitting point includes only one transmitting point, and the receiving point includes...) A total of 8 receiving points (all located in the sediment layer) form the sound wave propagation path, and the incident angle and emission angle are obtained; Secondly, according to Snell's law, determine which points are refraction points among all contact points corresponding to each receiving point at different scanning sound speeds: those that satisfy Snell's law are the refraction points corresponding to the receiving point at the current scanning sound speed, and the path formed by "emission point-refraction point-receiving point" is the propagation path of the sound wave at a given scanning sound speed.

[0048] Snell's law formula is as follows: (4) Angle of incidence For the angle of refraction, This is the speed of sound in water (which can be actually measured using a sound velocity meter). This represents the scanning sound velocity corresponding to the contact point.

[0049] Finally, the distance between the emission point and the refraction point is divided by the speed of sound in water to obtain the travel time in water; the distance between the refraction point and the receiving point is divided by the current scanning speed of sound to obtain the travel time in the sediment layer; the travel time in water and the travel time in the sediment layer are added together to obtain the travel time at the current scanning speed of sound.

[0050] If the receiving point is located in water, there is no need to determine the travel time through the velocity scanning method. The corresponding travel time is the distance between the transmitting point and the receiving point divided by the speed of sound in water, and this travel time is a fixed value.

[0051] like Figure 6 This is a specific embodiment with eight receiving points all located in the sediment layer, where the scanning sound velocity range is set to 1700:10:2300 m / s. Blue represents the travel time of the sediment layer sound field obtained in S3, and green represents the total travel time of the propagation path corresponding to each channel under different scanning sound velocities. This invention is also applicable to cases where some receiving points are located in water. Assuming the first receiving point (the receiving point at the top of the detection device) is located in water, the y-value for channel number 1 in the travel time curve is a fixed value, and all travel time curves start from this fixed value.

[0052] S5: Iterate through all channels within the given scanning sound velocity range to obtain the travel time of each channel, and plot the travel time curves composed of the travel times of each channel under the current scanning sound velocity. Perform least-squares matching of all travel time curves with the travel time of the sedimentary sound field obtained in S3. The minimum squared error value corresponds to the sound velocity of the sedimentary layer.

[0053] The specific steps are as follows: Using the scanning sound velocity as the unit of calculation, the difference between the travel time of each channel on the travel time curve and the travel time in the sedimentary layer sound field at each scanning sound velocity is calculated. The differences are then squared and summed to obtain the squared error value at the current scanning sound velocity. The minimum squared error value corresponds to the sedimentary layer sound velocity. The specific calculation formula is as follows: (5) in, This represents the squared error value corresponding to the current scanning sound velocity, where k is the total number of channels. This represents the travel time of the j-th channel on the travel time curve at the current scanning sound speed. Let be the travel time of the j-th channel in the acoustic field of the sediment layer.

[0054] like Figure 7 The figure shown is a least-squares matching result diagram of a specific embodiment of the present invention within a given scanning sound velocity range of 1700:10:2300m / s. It can be found that the scanning sound velocity corresponding to the least square error value is 1900m / s.

[0055] like Figure 8 The diagram shows the propagation paths of eight receiving points of the detection device at a sound velocity of 1900 m / s in the sediment layer according to a specific embodiment of the present invention. Src is the emission point, the black dashed line is the interface between the seawater and the sediment layer, and the black x-shaped symbol represents a refraction point.

[0056] S6, using the sedimentary layer sound velocity obtained in S5 as the screening condition, screen all refraction points and corresponding propagation paths within the scanning sound velocity range in S4, and obtain the propagation path corresponding to the refraction point under the sedimentary layer sound velocity as the final propagation path. S7 employs an acoustic attenuation scanning method to calculate the amplitude of all channels within a given acoustic attenuation range, and plots amplitude curves composed of different channel amplitudes under the current acoustic attenuation. All amplitude curves are then matched with the amplitude of the calibrated deposition layer acoustic field in S3 using a least-squares method, the principle of which is the same as in S5. The acoustic attenuation corresponding to the least squares error value is the acoustic attenuation coefficient of the deposition layer.

[0057] Within a given sound attenuation range, traverse all refraction points in S6 with a certain step size, and calculate the sound attenuation of each refraction point within the given sound attenuation range. Below, the corresponding amplitude The calculation process is as follows: (6) (7) in, The received amplitude, For the set launch amplitude, The attenuation of sound in water can be measured by a sound velocity meter; , These represent the propagation distances of the signal in the water and sediment layer along the propagation path, respectively, calculated from the propagation path. The amplitude transmission coefficient, , The densities of water and sediment layers are respectively. , Here, θ represents the angle of incidence and the angle of refraction, respectively, and G is the geometric diffusion coefficient, G = 1 / ( + ).

[0058] If the receiving point is located in water, there is no need to determine the amplitude using the acoustic attenuation scanning method; the corresponding amplitude is the transmitted amplitude. Multiply by the geometric diffusion coefficient, which is 1 / the distance between the transmitter and receiver, and this amplitude is a fixed value.

[0059] like Figure 9 The diagram shows a specific embodiment with eight receiving points all located within the sediment layer. The scanning acoustic attenuation range is set to 3:0.5:8 dB / m. Blue represents the amplitude of the calibrated sediment layer acoustic field obtained in S3, and green represents the amplitude simulated for each propagation path under the current scanning acoustic attenuation. This invention is also applicable to cases where some receiving points are located in water. Assuming the first receiving point (the uppermost receiving point of the detection device) is located in water, the y-value of channel number 1 in the amplitude curve is a fixed value, and all amplitude curves start from this fixed value.

[0060] like Figure 10 The least squares fitting results of the acoustic attenuation range of 3:0.5:8dB / m in a specific embodiment of the present invention can be seen as follows: the acoustic attenuation corresponding to the minimum error is 5dB / m. Therefore, the acoustic attenuation coefficient of the deposition layer corresponding to this specific embodiment is 5 dB / m.

[0061] The acoustic attenuation coefficient of sedimentary layers obtained in this invention provides a crucial basis for effectively determining the geological properties of the seabed when direct measurement is not possible. This coefficient accurately reflects the attenuation characteristics of sedimentary layers on the propagation of energy such as sound waves or elastic waves, thereby indirectly revealing the physical structure and composition of seabed sedimentary layers. By analyzing the lateral variation law of the acoustic attenuation coefficient, seabed stratigraphic interfaces can be further identified, sedimentary types can be determined, soil mechanical properties can be assessed, and preliminary inferences can be made regarding the occurrence of seabed resources such as natural gas hydrates and oil and gas.

[0062] The embodiments described above are merely preferred embodiments of the present invention and are not intended to limit the invention. Those skilled in the art can make various changes and modifications without departing from the spirit and scope of the invention. Therefore, all technical solutions obtained through equivalent substitution or transformation fall within the protection scope of the present invention.

Claims

1. A method for calculating in-situ acoustic parameters of a detection device that has not fully penetrated a sedimentary layer, characterized in that, The detection device comprises a transmitting point and multiple receiving points. The m receiving points located in the water are defined as the first receiving points, and the n receiving points located in the sediment layer are defined as the second receiving points, where m ≥ 0 and n ≥ 1. The method includes the following steps: S1, perform consistency calibration on the collected acoustic data of the seabed sediment layer based on the underwater reference acoustic field to obtain the calibrated sediment layer acoustic field; the underwater reference acoustic field is calculated using measured underwater acoustic data; S2, envelope fitting is performed on the reference sound field in water and the calibrated sound field of the sediment layer to obtain the envelope curve in water and the envelope curve of the sediment layer; S3, based on the envelope curve in water and the envelope curve of the sedimentary layer, the travel time and amplitude of the acoustic field of the sedimentary layer are obtained; S4. For the first receiving point, the corresponding travel time is obtained by dividing the distance between the transmitting point and the first receiving point by the speed of sound in water. The line connecting the transmitting point and the first receiving point is the first propagation path. For the second receiving point, all refraction points within the scanning speed range are obtained by using Snell's law and the sound speed scanning method. The travel time is further calculated based on the first propagation path corresponding to the refraction points. S5, connect the fixed travel time corresponding to the first receiving point with the travel time corresponding to the second receiving point under the same scanning sound speed in the order of the receiving points to obtain the travel time curves under different scanning sound speeds; perform least squares matching of all travel time curves with the travel time of the sedimentation layer sound field to obtain the corresponding square error value, and the scanning sound speed corresponding to the least square error value is the sound speed of the sedimentation layer. S6, based on the sound velocity of the sedimentary layer, select the second propagation path at the sound velocity of the sedimentary layer from all the first propagation paths in S4; S7, for the first receiving point, the corresponding amplitude is calculated by multiplying the set transmission amplitude by the geometric diffusion coefficient; for the second receiving point, the amplitudes corresponding to each second propagation path within the sound attenuation range are calculated using the sound attenuation scanning method. S8. Connect the fixed amplitude corresponding to the first receiving point and the amplitude corresponding to the second receiving point under the same sound attenuation according to the receiving point order to obtain the amplitude curves corresponding to different sound attenuations. Perform least squares matching of all amplitude curves with the sound field amplitude of the sedimentation layer to obtain the corresponding square error value. The sound attenuation corresponding to the least square error value is the sedimentation layer attenuation coefficient.

2. The in-situ acoustic parameter calculation method for a detection device that has not fully penetrated the sedimentary layer according to claim 1, characterized in that, S1 specifically includes: S101, denoise the acoustic data collected in the water and seabed sedimentary layers to obtain the actual underwater acoustic field and the actual sedimentary layer acoustic field; S102 utilizes the acoustic properties of water to establish an underwater reference acoustic field based on a zero-phase bandwidth wavelet. S103, Solve for the matched filter between the actual underwater sound field and the underwater reference sound field; S104 applies the matched filter to the actual deposition layer acoustic field and calculates the calibrated deposition layer acoustic field.

3. The in-situ acoustic parameter calculation method for a detection device that has not fully penetrated the sedimentary layer according to claim 1, characterized in that, In S4, the methods for obtaining the refraction point corresponding to the second receiving point and the first propagation path include: Within a predefined range of scanning sound speed, the detection device traverses all contact points on the interface between the sediment layer and the seawater at a predefined sound speed step size, obtaining all propagation paths formed by the contact points and the transmitting and receiving points of the detection device, as well as the corresponding incident and emission angles. According to Snell's law, contact points that meet the requirements are selected. If the incident angle and emission angle corresponding to the contact point satisfy Snell's law, the contact point is determined to be a refraction point, and the corresponding propagation path is retained as the first propagation path. Otherwise, the contact point and the corresponding propagation path are deleted.

4. The in-situ acoustic parameter calculation method for a detection device that has not fully penetrated the sedimentary layer according to claim 1, characterized in that, S3 specifically includes: S301, the travel time difference between the underwater envelope curve and the sedimentary layer envelope curve is calculated using the cross-correlation method; S302, extract the peak travel time of the reference sound field in the water in S1, and add the peak travel time to the travel time difference to obtain the travel time of the sound field in the sediment layer; S303, extract the main envelope of the sediment layer envelope curve, and calculate the average value of the main envelope as the acoustic field amplitude of the sediment layer.

5. The in-situ acoustic parameter calculation method for a detection device that has not fully penetrated the sedimentary layer according to claim 1, characterized in that, In S7, the value of the geometric diffusion coefficient is calculated by dividing 1 by the distance of the second propagation path corresponding to the first receiving point.

6. The in-situ acoustic parameter calculation method for a detection device that has not fully penetrated the sedimentary layer according to claim 1, characterized in that, The travel time corresponding to the second receiving point is obtained by adding the travel time in water to the travel time in the sediment layer; the travel time in water is obtained by dividing the distance between the transmitting point and the refraction point by the speed of sound in water; the travel time in the sediment layer is obtained by dividing the distance between the refraction point and the second receiving point by the current scanning speed of sound.

7. The in-situ acoustic parameter calculation method for a detection device that has not fully penetrated the sedimentary layer according to claim 1, characterized in that, For the second receiving point, the first propagation path corresponding to the refraction point is a broken line that starts from the transmitting point of the detection device, passes through the refraction point, and finally reaches the receiving point of the detection device.

8. The in-situ acoustic parameter calculation method for a detection device that has not fully penetrated the sedimentary layer according to claim 1, characterized in that, The sound attenuation scanning method refers to sequentially traversing all the second propagation paths corresponding to the second receiving point in S6, traversing the given sound attenuation range with a certain step size, and obtaining the amplitude of the second propagation path corresponding to each second receiving point under the corresponding sound attenuation.

9. The in-situ acoustic parameter calculation method for a detection device that has not fully penetrated the sedimentary layer according to claim 8, characterized in that, Given a sound attenuation, the formula for calculating the amplitude is: ； in, For amplitude, Given the current sound attenuation, For the set launch amplitude, For sound attenuation in water, , These represent the propagation distances of the signal in the water and sediment layer, respectively, in the second propagation path. denoted as amplitude transmission coefficient, and G as geometric diffusion coefficient.

10. The in-situ acoustic parameter calculation method for a detection device that has not fully penetrated the sedimentary layer according to claim 9, characterized in that, The formula for calculating the amplitude transmission coefficient is: ； in, , The densities of water and sediment layers are respectively. , These are the angle of incidence and the angle of refraction, respectively. The speed of sound in water, The velocity of sound in the sediment layer.

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