A seabed sediment strength testing apparatus and method

Abstract

The application provides a seabed sediment strength testing device and a testing method. The deep-sea seabed sediment strength testing device comprises a cone tip assembly, a pressure-resistant cabin, a driving device and a controller. The driving device is used for driving the driving rod to retract or extend the cylindrical part. When the testing device penetrates to a specified depth under the action of its own gravity, the driving rod drives the cone tip assembly to uniformly penetrate to the specified depth under the control of the driving device, that is, a static cone penetration test is added after a free-fall cone penetration test. The free-fall dynamic cone penetration test and the static cone penetration test are completed in sequence by using the same device in one penetration process. The correction parameter is determined by the relationship between the static cone tip resistance and the dynamic cone tip resistance. The dynamic cone tip resistance is corrected by the correction parameter to obtain the corrected dynamic cone tip resistance. The seabed sediment strength is determined by the corrected dynamic cone tip resistance, so that the efficiency and accuracy of the deep-sea seabed sediment strength testing are greatly improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of seabed sediment detection, and in particular relates to a seabed sediment strength testing device and a testing method. Background Art

[0002] In recent years, with the further development of ocean exploration and development, marine resource development and marine engineering have begun to move deeper into the deep sea. These include nodule mining, methane hydrate mining, and floating offshore wind power. To ensure the safe and efficient development and construction of these resources and projects, it is necessary to test and survey the undrained shear strength of seafloor sediments. Since most of these projects rely on shallow sediments, accurately determining the undrained shear strength of shallow sediments is particularly important.

[0003] Seabed sediments have the significant characteristics of high water content, great thickness, saturated looseness and easy disturbance. Therefore, the use of traditional exploration methods is no longer appropriate. For example, on-site sampling, whether columnar or bulk, is disturbed, which loses the structural characteristics of the on-site sediments, resulting in a large difference from the measured strength of the on-site sediments, and cannot truly reflect the on-site sediment strength. For engineering practice, this will lead to increased engineering costs.

[0004] Therefore, obtaining the undrained shear strength of sediments through on-site geotechnical investigations is a more appropriate method. A widely used technique is the static penetration test, which involves penetrating a tapered probe of standard shape and size into the formation at a constant speed and measuring the penetration resistance of the cone tip to determine the undrained shear strength of the sediments. Conducting static penetration tests offshore requires either a large construction platform on the water surface or large-scale equipment deployed to the seabed.

[0005] However, in deep-sea environments, the extremely large water depth limits its use, and the economic and time costs increase significantly, with the economic cost reaching millions of yuan. Against this background, a new type of geotechnical exploration method has emerged, which is to raise the probe rod in the static penetration test to form a needle-shaped probe, that is, a free-fall probe. It uses its own gravity as power to penetrate the seabed sediment from the sea surface in a free-fall manner, and records the cone tip resistance to calculate the undrained shear strength of the sediment. However, since this method penetrates the soil at high speed, the resistance obtained is much higher than the result of the static penetration test, so the result needs to be rate-corrected. However, the existing effective technical means is to manually estimate and determine the correction parameters based on the geological conditions, and select the correction parameters within a reasonable range. In this case, since the geological conditions in the same area cannot be exactly the same, there are deviations in the manually determined correction parameters, which often lead to significant differences between the correction parameters and the actual position, resulting in inaccurate correction results and ultimately inaccurate strength determination.

[0006] The above information disclosed in this background technology is only used to increase the understanding of the background technology of this application. Therefore, it may contain information that does not constitute the prior art known to ordinary technicians in this field. Summary of the Invention

[0007] In view of the above problems in the prior art, the present invention proposes a device and method for testing the strength of seabed sediments, which solves the technical problem of poor testing accuracy of the free-fall penetrometer in the prior art.

[0008] In order to achieve the above-mentioned purpose, the present invention adopts the following technical solutions:

[0009] A device for testing seabed sediment strength, comprising:

[0010] The cone tip assembly includes a cone tip probe, a cone shoulder probe rod, and a cone tip resistance sensor, wherein the cone tip probe is connected to the cone shoulder probe rod, and the cone tip resistance sensor is located on the cone tip probe;

[0011] a pressure-resistant cabin, wherein the pressure-resistant cabin is connected to a cylindrical member;

[0012] a drive device located in the pressure cabin, comprising a drive rod, a portion of which extends out of the pressure cabin and is located in the cylindrical member, one end of which is connected to the probe rod at the conical shoulder; the drive device is used to drive the drive rod to retract or extend into the cylindrical member;

[0013] an accelerometer, used to detect acceleration;

[0014] The controller is configured to receive the dynamic cone tip resistance detected by the cone tip resistance sensor during the free-fall penetration of the test device into the soil; after the free penetration of the test device stops, control the operation of the drive device to make the drive rod extend out of the cylindrical member at a uniform speed, and the cone tip assembly penetrates the soil at a uniform speed, and receive the static cone tip resistance detected by the cone tip resistance sensor; determine a correction parameter based on the relationship between the static cone tip resistance and the dynamic cone tip resistance, correct the dynamic cone tip resistance based on the correction parameter to obtain the corrected dynamic cone tip resistance, and determine the strength of the seabed sediment based on the corrected dynamic cone tip resistance.

[0015] In the above-mentioned device for testing the strength of seabed sediments, the controller is configured as follows:

[0016] According to the last data of dynamic cone tip resistance / [(v / d) / (v / d) ref ] β = The correction parameter β is calculated from the first data of the static cone tip resistance, where v is the velocity calculated from the acceleration detected by the accelerometer, d is the diameter of the probe at the cone tip, and the subscript ref is the reference value;

[0017] Correct the other dynamic cone tip resistance according to the calculated correction parameter β to obtain the corrected other dynamic cone tip resistance: Corrected other dynamic cone tip resistance = other dynamic cone tip resistance / [(v / d) / (v / d)] ref ] β .

[0018] In the seabed sediment strength testing device as described above, the cylindrical member is a cylindrical pressure chamber, and the cylindrical pressure chamber is connected to the pressure chamber.

[0019] In the above-mentioned device for testing the strength of seabed sediments, the cone tip probe and the probe rod at the cone tip are integrally formed or threadedly connected.

[0020] The seabed sediment strength testing device as described above,

[0021] The driving device includes a cylinder, and the driving rod is a piston rod of the cylinder;

[0022] Alternatively, the driving device includes a hydraulic cylinder, and the driving rod is a piston rod of the hydraulic cylinder;

[0023] Alternatively, the driving device includes a driving motor and a transmission assembly, and the transmission assembly transmits the driving force of the driving motor to the driving rod.

[0024] As described above, in the device for testing the strength of seabed sediments, during the process of the free-falling penetration of the testing device into the soil, the driving rod is retracted to the position where the probe rod contacts the cylindrical member at the cone shoulder.

[0025] In the seabed sediment strength testing device as described above, a power supply is provided in the pressure chamber.

[0026] As described above, in the seabed sediment strength testing device, a sealing ring sealedly connected to the driving rod is provided on the inner wall of the cylindrical member and / or the inner wall of the pressure chamber.

[0027] The testing method of the seabed sediment strength testing device as described above is as follows:

[0028] The test device falls freely and penetrates the soil;

[0029] During the process of the testing device penetrating the soil, the cone tip resistance sensor detects the dynamic cone tip resistance;

[0030] After the free penetration stops, the driving device is controlled to move so that the driving rod extends out of the cylindrical member at a uniform speed, and the cone tip assembly penetrates into the soil at a uniform speed, and the cone tip resistance sensor detects the static cone tip resistance;

[0031] The correction parameter is determined by the relationship between the static cone tip resistance and the dynamic cone tip resistance. The dynamic cone tip resistance is corrected by the correction parameter to obtain the corrected dynamic cone tip resistance. The seabed sediment strength is determined by the corrected dynamic cone tip resistance.

[0032] The test method of the seabed sediment strength test device as described above is based on the last data of the dynamic cone tip resistance / [(v / d) / (v / d) ref ] β = The correction parameter β is calculated from the first data of the static cone tip resistance, where v is the velocity calculated from the acceleration detected by the accelerometer, d is the diameter of the probe at the cone tip, and the subscript ref is the reference value;

[0033] Correct the other dynamic cone tip resistance according to the calculated correction parameter β to obtain the corrected other dynamic cone tip resistance: Corrected other dynamic cone tip resistance = other dynamic cone tip resistance / [(v / d) / (v / d)] ref ] β .

[0034] Compared with the prior art, the advantages and positive effects of the present invention are as follows: the deep-sea bottom sediment strength testing device of the present invention includes a cone tip assembly, a pressure-resistant chamber, a drive device, and a controller. The drive device is used to drive the drive rod to retract or extend the cylindrical member. After the testing device penetrates the specified depth under the action of its own weight, the drive rod, under the control of the drive device, pushes the cone tip assembly to penetrate to the specified depth at a uniform speed, i.e., a set of static penetration tests is added after the free-fall penetration test. The same device is used to complete the free-fall penetration test and the static penetration test in a single penetration process. The correction parameter is determined based on the relationship between the static cone tip resistance and the dynamic cone tip resistance. The dynamic cone tip resistance is corrected using the correction parameter to obtain the corrected dynamic cone tip resistance. The seabed sediment strength is determined based on the corrected dynamic cone tip resistance, greatly improving the efficiency and accuracy of deep-sea bottom sediment strength testing and providing a more powerful technical means for deep-sea resource development and engineering construction. The present invention realizes the on-site rapid calibration of the rate effect correction parameter of the free-fall penetration test, making the results of the free-fall penetration test more accurate and efficient.

[0035] Other features and advantages of the present invention will become more apparent after reading the detailed description of the present invention in conjunction with the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following is a brief introduction to the drawings required for use in the embodiments. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0037] Figure 1 Schematic diagram of the appearance of a testing device according to a specific embodiment of the present invention.

[0038] Figure 2 It is a longitudinal cross-sectional view of a testing device according to a specific embodiment of the present invention.

[0039] Figure 3 This is a longitudinal cross-sectional view of a driving rod of a testing device in an extended state according to a specific embodiment of the present invention.

[0040] Figure 4 This is a comparison curve of the cone tip resistance corresponding to several penetration depths in the same area of ​​a specific embodiment of the present invention and the prior art.

[0041] Figure 5 The figure is a flow chart of the testing process of a specific embodiment of the present invention.

[0042] In the picture:

[0043] 11. Cone tip probe; 12. Probe at cone shoulder; 13. Cone tip resistance sensor; 21. Cylindrical pressure chamber; 211. Sealing ring; 22. Pressure chamber;

[0044] 31. Driving rod; 32. Cylinder; 33. Air pump; 34. Air pipe; 35. Valve. DETAILED DESCRIPTION

[0045] To make the objectives, technical solutions and advantages of the embodiments of the present invention more clear, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention.

[0046] In the description of the present invention, it should be noted that the directions or positional relationships indicated by the terms "upper", "lower", "left", "right", etc. are based on the positional relationships shown in the accompanying drawings, with the direction close to the center of the kettle lid being "inside", and vice versa being "outside". The terms are only used to facilitate the description of the present invention and to simplify the description, and are not intended to indicate or imply that the device or element referred to must have a specific direction, be constructed and operated in a specific direction, and therefore cannot be understood as limiting the present invention. In addition, the terms "first", "second", and "third" are used for descriptive purposes only and cannot be understood as indicating or implying relative importance; features defined as "first" and "second" may explicitly or implicitly include one or more of such features. In the description of the present invention, "multiple" means two or more, unless otherwise clearly and specifically defined.

[0047] In the present invention, unless otherwise expressly specified or limited, the terms "mounted," "connected," "connect," "fixed," etc. should be understood broadly. For example, they may refer to fixed connection, detachable connection, or integration; mechanical connection or electrical connection; direct connection or indirect connection through an intermediate medium; internal communication between two components or interaction between two components. Those skilled in the art will understand the specific meanings of the above terms in the present invention based on specific circumstances.

[0048] In the present invention, unless otherwise expressly specified or limited, a first feature being "above" or "below" a second feature may include the first and second features being in direct contact, or may include the first and second features being in contact not directly but through another feature between them. Furthermore, a first feature being "above," "above," and "above" a second feature may include the first feature being directly above or obliquely above the second feature, or may simply mean that the first feature is higher in level than the second feature. A first feature being "below," "below," and "below" a second feature may include the first feature being directly below or obliquely below the second feature, or may simply mean that the first feature is lower in level than the second feature.

[0049] The disclosure below provides many different embodiments or examples for realizing different structures of the present invention. In order to simplify the disclosure of the present invention, the components and settings of specific examples are described below. Of course, they are merely examples and are not intended to limit the present invention. In addition, the present invention may repeat reference numbers and / or reference letters in different examples. Such repetition is for the purpose of simplicity and clarity and does not in itself indicate the relationship between the various embodiments and / or settings discussed. In addition, the present invention provides examples of various specific processes and materials, but those skilled in the art will recognize the application of other processes and / or the use of other materials.

[0050] The device for testing the strength of seabed sediments is a device that can freely fall and detect the dynamic cone tip resistance during the process of free fall penetration into the soil. After the free fall ends (that is, when it is stationary), the cone tip assembly is controlled to extend at a uniform speed to detect the static cone tip resistance during the uniform speed penetration into the soil. The correction parameter β is determined based on the relationship between the static cone tip resistance and the dynamic cone tip resistance. The dynamic cone tip resistance is corrected by the correction parameter β to obtain the corrected dynamic cone tip resistance. The strength of seabed sediments is determined by the corrected dynamic cone tip resistance.

[0051] like Figure 1-Figure 3 As shown, the seabed sediment strength testing device includes: a cone tip assembly, a pressure chamber, a driving device, an accelerometer and a controller.

[0052] The cone tip assembly includes a cone tip probe 11, a probe rod 12 at the cone shoulder, and a cone tip resistance sensor 13.

[0053] The cone tip probe 11 is a cone, and the outer diameter of the probe rod 12 at the cone shoulder is adapted to the maximum outer diameter of the cone and is connected to the bottom surface of the cone.

[0054] The cone tip probe 11 is fixedly connected to the probe rod 12 at the cone shoulder.

[0055] The cone tip probe 11 is threadedly connected to the probe rod 12 at the cone shoulder, which is convenient for disassembly, installation and replacement of the internal cone tip resistance sensor 13.

[0056] In some other embodiments, the cone tip probe 11 and the probe rod 12 at the cone shoulder may also be integrally formed.

[0057] The cone tip resistance sensor 13 is located on the cone tip probe 11 .

[0058] The pressure-resistant cabin 22 is connected to a cylindrical member, and the pressure-resistant cabin 22 is connected to one end of the cylindrical member.

[0059] The cylindrical component is a cylindrical pressure-resistant cabin 21 , and the cylindrical pressure-resistant cabin 21 is fixedly connected to the pressure-resistant cabin 22 .

[0060] In some other embodiments, the cylindrical pressure cabin 21 and the pressure cabin 22 are integrally formed.

[0061] The cylindrical pressure-resistant cabin 21 and the pressure-resistant cabin 22 themselves have a sealing and pressure-resistant effect, which can ensure deep-sea operations.

[0062] Part of the driving device is located in the pressure cabin 22. The driving device includes a driving rod 31. Part of the driving rod 31 extends out of the pressure cabin 22 and is located in the cylindrical pressure cabin 21. One end of the driving rod 31 is connected to the probe rod 12 at the cone shoulder. The driving device is used to drive the driving rod 31 to retract or extend out of the cylindrical pressure cabin 21.

[0063] The cone tip assembly is connected to the drive rod 31 of the drive device, which can drive the cone tip assembly to move. The controller controls the operation of the drive device and receives detection signals from the sensor. The cone tip assembly is not connected to the cylindrical pressure-resistant cabin 21.

[0064] The controller may be located within the pressure-resistant cabin 22 .

[0065] In some other embodiments, a communication module may be provided within the pressure-resistant chamber 22, with the controller located outside the test apparatus. The controller communicates with the communication module within the pressure-resistant chamber 22 to transmit control signals and receive test signals. The drive rod 31 is sealedly connected to the cylindrical pressure-resistant chamber 21 to ensure the sealing of the pressure-resistant chamber 22.

[0066] Specifically, a sealing ring 211 is provided on the inner wall of the cylindrical pressure-resistant cabin 21, and the sealing ring 211 is in sealing sliding contact with the driving rod 31. Preferably, the sealing ring 211 is close to the free end of the cylindrical pressure-resistant cabin 21, that is, the end of the cylindrical pressure-resistant cabin 21 away from the pressure-resistant cabin 22.

[0067] In some other embodiments, the driving rod 31 is sealed to the pressure-resistant cabin 22 , and a sealing ring may be provided on the inner wall where the pressure-resistant cabin 22 contacts the driving rod 31 .

[0068] In some other embodiments, the driving rod 31 is sealedly connected to the pressure cabin 22 and the cylindrical pressure cabin 21, and a sealing ring may be set on the inner wall where the pressure cabin 22 contacts the driving rod 31, and a sealing ring may be set on the inner wall where the cylindrical pressure cabin 21 and the driving rod 31 are released.

[0069] The driving device includes an air cylinder 32, an air pump 33, an air pipe 34 and a valve 35, and the driving rod 31 is the piston rod of the air cylinder.

[0070] The cylinder body of the cylinder 32 is installed in the pressure cabin 22, and part of the drive rod 31 extends from the pressure cabin 22 and is located in the cylindrical pressure cabin 21. The outer diameter of the drive rod 31 is adapted to the inner diameter of the pressure cabin 22 to ensure smooth movement of the drive rod 31.

[0071] The air pump 33, air pipe 34 and valve 35 are all located in the pressure cabin 22. The air pump 33 is connected to the cylinder 32 through two air pipes 34. The two valves 35 are respectively located on the two air pipes 34. The valves 35 are controlled by a controller. The controller controls the opening and closing of the two valves 35 to control the extension and retraction of the drive rod 31.

[0072] The controller controls the driving rod 31 to extend at a constant speed.

[0073] In some other embodiments, the driving device includes a hydraulic cylinder, and the driving rod is a piston rod of the hydraulic cylinder.

[0074] In some other embodiments, the driving device includes a driving motor and a transmission assembly, and the transmission assembly transmits the driving force of the driving motor to the driving rod 31 .

[0075] The transmission component is a worm gear component. The accelerometer is used to detect the acceleration of the test device.

[0076] When the controller is located in the pressure-resistant cabin 22 , the signal line of the cone tip resistance sensor 13 passes through the driving rod 31 and is electrically connected to the controller.

[0077] The pressure cabin 22 is provided with hardware such as a power supply and a storage device.

[0078] The controller is configured to receive the dynamic cone tip resistance detected by the cone tip resistance sensor 13 during the free-fall penetration of the test device into the soil; after the free penetration of the test device stops, the controller controls the operation of the driving device to make the driving rod 31 extend out of the cylindrical pressure-resistant cabin 21 at a uniform speed, and the cone tip assembly penetrates into the soil at a uniform speed, and receives the static cone tip resistance detected by the cone tip resistance sensor; the correction parameter β is determined based on the relationship between the static cone tip resistance and the dynamic cone tip resistance, the dynamic cone tip resistance is corrected by the correction parameter β, and the corrected dynamic cone tip resistance is obtained, and the strength of the seabed sediment is determined based on the corrected dynamic cone tip resistance.

[0079] The controller is configured to calculate the dynamic cone tip resistance based on the last data of the dynamic cone tip resistance / [(v / d) / (v / d) ref ] β = The correction parameter β is calculated from the first data of the static cone tip resistance, where v is the velocity calculated from the acceleration detected by the accelerometer, d is the diameter of the probe at the cone tip, and the subscript ref is the reference value;

[0080] Correct the other dynamic cone tip resistance according to the calculated correction parameter β to obtain the corrected other dynamic cone tip resistance: Corrected other dynamic cone tip resistance = other dynamic cone tip resistance / [(v / d) / (v / d)] ref ] β .

[0081] The dynamic cone tip resistance includes several data points corresponding to various penetration depths. The penetration depth can be obtained by quadratic integration of the acceleration. Therefore, this embodiment does not require estimating the correction parameter β. Instead, it directly couples dynamic and static penetration, calibrating the correction parameter β on-site. The resulting correction parameter β can reflect the local geological conditions with higher accuracy, thereby improving the accuracy of strength determination.

[0082] In some embodiments, the dynamic cone tip resistance includes Ft1, Ft2, ..., Ftn corresponding to n penetration depths, and the static cone tip resistance includes q1 corresponding to a specific penetration depth. The specific penetration depth is the depth after free penetration stops + the length of the drive mechanism extended.

[0083] Let the modified nth dynamic cone tip resistance qtn = Ftn / [(vn / d) / (vn / d)] ref ] β =q1, and the correction parameter β is calculated.

[0084] …

[0085] The corrected second dynamic cone tip resistance qt2 = Ft2 / [(v2 / d) / (v2 / d)] ref ] β .

[0086] Corrected first dynamic cone tip resistance qt1 = Ft1 / [(v1 / d) / (v1 / d)] ref ] β .

[0087] Among them, v1, v2, …, vn are the velocities corresponding to the dynamic cone tip resistance, which can be calculated from the acceleration detected by the accelerometer.

[0088] The seabed sediment strength is determined using the modified dynamic cone tip resistance. This is prior art and will not be described in detail. The seabed sediment strength includes several seabed sediment strengths corresponding to several penetration depths.

[0089] During the free-fall penetration of the test device into the soil, the driving rod 31 is retracted to the position where the probe rod 12 contacts the cylindrical pressure-resistant cabin 21 at the cone shoulder.

[0090] The extended length of the driving rod 31 is fixed, and the extended length can be adjusted by replacing the driving rod 31 with a different specification to change the uniform penetration distance.

[0091] The controller receives the acceleration detected by the accelerometer. When the acceleration of the device is 0, that is, after the power penetration is completed, the driving device is started to make the driving rod 31 penetrate downward to a certain depth. When the penetration reaches the limit depth, the driving device gradually retracts the driving rod 31. When the driving rod 31 returns to its original length, a complete penetration process is completed.

[0092] During the dynamic penetration (free-fall) process, the probe rod 12 at the cone shoulder contacts but is not connected to the cylindrical pressure chamber 21, and the drive rod 31 is completely enclosed within the cylindrical pressure chamber 21. After the dynamic penetration is complete, the drive mechanism begins to operate, providing power to the drive rod 31, causing it to extend and propel the cone tip assembly into the sediment at a uniform speed. The probe rod 12 at the cone shoulder gradually separates from the cylindrical pressure chamber 21. This continues until the cone tip assembly reaches the designated depth, completing static penetration. The tip resistance data collected by the cone tip resistance sensor 13 during both dynamic and static penetrations is recorded in a controller or storage device, thereby calibrating the soil rate effect correction parameter β and measuring the soil shear strength. When penetration is complete, the drive mechanism provides power to the drive rod 31, causing it to retract until the probe rod 12 at the cone shoulder re-contacts the cylindrical pressure chamber 21. The device is then recovered from the seabed for testing at the next location.

[0093] This embodiment can easily determine the correction parameters β corresponding to all test points, thereby improving the accuracy of intensity determination at each test point.

[0094] exist Figure 5In the example, the red curve represents the dynamic cone tip resistance during the dynamic penetration process. The curve is obtained from the measurement data during the dynamic penetration process of the free-fall probe in the prior art, and is also obtained from the measurement data during the dynamic penetration process of this embodiment.

[0095] The dark blue curve represents the static cone tip resistance during the static penetration process, which is obtained by conducting a static penetration test on a large construction platform on the water surface or a large working equipment deployed on the seabed in the background technology.

[0096] The orange curve is the corrected curve obtained by manually correcting the red curve when β=0.15.

[0097] The yellow curve is the corrected curve obtained by correcting the red curve when β=0.45 is manually determined.

[0098] The gray curve is obtained from the measurement data during the static penetration process of this embodiment.

[0099] The light blue curve is the β determined in this embodiment, which is a correction curve obtained by correcting the red curve.

[0100] To correct for the dynamic tip resistance and mitigate the effects of free fall on it, existing techniques rely on manually estimating a correction parameter, β, based on geological conditions. For example, manually determining a correction parameter of β = 0.15 results in an orange curve for the dynamic tip resistance; determining a correction parameter of β = 0.45 results in a yellow curve. Both the orange and yellow curves exhibit significant errors compared to the dark blue curve representing the static tip resistance during static penetration. This results in inaccurate corrections to the tip resistance and, consequently, inaccurate seafloor sediment strength.

[0101] This embodiment uses the last set of data of the red curve and the first set of data of the gray curve to determine the correction parameter β. The red curve is corrected according to the correction parameter β to obtain a light blue curve. The light blue curve and the dark blue curve basically coincide with each other, indicating that the dynamic cone tip resistance at the same penetration depth corrected in this embodiment is basically close to the static cone tip resistance, and the error between the two is very small. Therefore, this embodiment improves the accuracy of the determination of the cone tip resistance, thereby achieving the accuracy of determining the strength of seabed sediments tested by a low-cost testing device.

[0102] Testing method based on the above-mentioned seabed sediment strength testing device:

[0103] The test device falls freely and penetrates the soil.

[0104] During the process of the test device penetrating the soil, the cone tip resistance sensor detects the dynamic cone tip resistance and obtains a number of dynamic cone tip resistances corresponding to a number of penetration depths; during this process, the drive rod is retracted to the position where the probe rod contacts the cylindrical member at the cone shoulder.

[0105] After free penetration stops, the driving device is controlled to make the driving rod extend out of the cylindrical part at a uniform speed, and the cone tip assembly penetrates into the soil at a uniform speed. The cone tip resistance sensor detects the static cone tip resistance and obtains a number of static cone tip resistances corresponding to a number of penetration depths.

[0106] The correction parameter β is determined by the relationship between the static cone tip resistance and the dynamic cone tip resistance. The dynamic cone tip resistance is corrected by the correction parameter β to obtain the corrected dynamic cone tip resistance. The seabed sediment strength is determined by the corrected dynamic cone tip resistance.

[0107] Among them, the method for determining the correction parameter β is:

[0108] According to the last data of dynamic cone tip resistance / [(v / d) / (v / d) ref ] β = The correction parameter β is calculated from the first data of the static cone tip resistance, where v is the velocity calculated from the acceleration detected by the accelerometer, d is the diameter of the probe at the cone tip, and the subscript ref is the reference value.

[0109] Correct the other dynamic cone tip resistance according to the calculated correction parameter β to obtain the corrected other dynamic cone tip resistance: Corrected other dynamic cone tip resistance = other dynamic cone tip resistance / [(v / d) / (v / d)] ref ] β .

[0110] Determine the seafloor sediment strength by corrected dynamic cone tip resistance.

[0111] In some embodiments, the testing process specifically includes the following steps:

[0112] S1. Release the test device from the operating vessel and allow it to fall freely and penetrate the soil.

[0113] The test device is connected to the workboat via a winch. After release, the power supply in the pressure cabin is powered, activating the cone tip sensor to record the dynamic cone tip resistance of the free-fall object penetrating the soil.

[0114] S2. When the test device penetrates the soil, the cone tip resistance sensor detects the dynamic cone tip resistance and obtains a number of dynamic cone tip resistances.

[0115] S3. When free penetration stops, the controller controls the driving device to work, so that the driving rod extends at a uniform speed and the cone tip assembly penetrates the soil at a uniform speed. At this time, the sensor still records data and obtains a number of static cone tip resistances.

[0116] S4. Determine a correction parameter β based on the relationship between the static cone tip resistance and the dynamic cone tip resistance, correct the dynamic cone tip resistance using the correction parameter β to obtain a corrected dynamic cone tip resistance, and determine the seabed sediment strength using the corrected dynamic cone tip resistance.

[0117] This embodiment can realize free-fall penetration and static penetration successively in one penetration process, realizes the on-site calibration of the rate effect correction parameter β required for correcting the free-fall penetration result, and thus can improve the efficiency and accuracy of the test at a low cost.

[0118] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit the same. Although the present invention has been described in detail with reference to the aforementioned embodiments, it is still possible for a person skilled in the art to modify the technical solutions described in the aforementioned embodiments, or to replace some of the technical features therein with equivalents. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions claimed to be protected by the present invention.

Claims

1. A device for testing the strength of seabed sediments, characterized in that: include: The cone tip assembly includes a cone tip probe, a cone shoulder probe rod, and a cone tip resistance sensor, wherein the cone tip probe is connected to the cone shoulder probe rod, and the cone tip resistance sensor is located on the cone tip probe; a pressure-resistant cabin, wherein the pressure-resistant cabin is connected to a cylindrical member; a driving device located in the pressure cabin, the driving device comprising a driving rod, a portion of the driving rod extending out of the pressure cabin and located in the cylindrical member, one end of the driving rod being connected to the probe rod at the conical shoulder; The driving device is used to drive the driving rod to retract or extend the cylindrical member; an accelerometer, used to detect acceleration; a controller configured to receive the dynamic cone tip resistance detected by the cone tip resistance sensor during the free fall penetration of the testing device into the soil; After the free penetration of the test device stops, the driving device is controlled to move so that the driving rod extends out of the cylindrical member at a uniform speed, and the cone tip assembly penetrates into the soil at a uniform speed, receiving the static cone tip resistance detected by the cone tip resistance sensor; The correction parameter is determined by the relationship between the static cone tip resistance and the dynamic cone tip resistance, and the dynamic cone tip resistance is corrected by the correction parameter to obtain the corrected dynamic cone tip resistance, and the seabed sediment strength is determined by the corrected dynamic cone tip resistance; The controller is configured as follows: According to the last data of dynamic cone tip resistance / [(v / d) / (v / d) ref ] β = The correction parameter β is calculated from the first data of the static cone tip resistance, where v is the velocity calculated by the acceleration, d is the diameter of the probe at the cone tip, and the subscript ref is the reference value; Correct the other dynamic cone tip resistance according to the calculated correction parameter β to obtain the corrected other dynamic cone tip resistance: Corrected other dynamic cone tip resistance = other dynamic cone tip resistance / [(v / d) / (v / d)] ref ] β .

2. The device for testing seabed sediment strength according to claim 1, characterized in that: The cylindrical member is a cylindrical pressure-resistant cabin, and the cylindrical pressure-resistant cabin is connected to the pressure-resistant cabin.

3. The device for testing seabed sediment strength according to claim 1, characterized in that: The cone tip probe and the probe rod at the cone tip are integrally formed or threadedly connected.

4. The device for testing seabed sediment strength according to claim 1, characterized in that: The driving device includes a cylinder, and the driving rod is a piston rod of the cylinder; Alternatively, the driving device includes a hydraulic cylinder, and the driving rod is a piston rod of the hydraulic cylinder; Alternatively, the driving device includes a driving motor and a transmission assembly, and the transmission assembly transmits the driving force of the driving motor to the driving rod.

5. The device for testing seabed sediment strength according to claim 1, characterized in that: During the free-fall penetration of the testing device into the soil, the driving rod is retracted to the position where the probe rod contacts the cylindrical member at the cone shoulder.

6. The device for testing seabed sediment strength according to claim 1, characterized in that: A power supply is provided in the pressure-resistant cabin.

7. The device for testing seabed sediment strength according to claim 1, characterized in that: A sealing ring sealedly connected to the driving rod is provided on the inner wall of the cylindrical member and / or the inner wall of the pressure-resistant cabin.

8. A testing method based on the seabed sediment strength testing device according to any one of claims 1 to 7, characterized in that: The test method is: The test device falls freely and penetrates the soil; During the process of the testing device penetrating the soil, the cone tip resistance sensor detects the dynamic cone tip resistance; After the free penetration stops, the driving device is controlled to move so that the driving rod extends out of the cylindrical member at a uniform speed, and the cone tip assembly penetrates into the soil at a uniform speed, and the cone tip resistance sensor detects the static cone tip resistance; The correction parameter is determined by the relationship between the static cone tip resistance and the dynamic cone tip resistance, and the dynamic cone tip resistance is corrected by the correction parameter to obtain the corrected dynamic cone tip resistance, and the seabed sediment strength is determined by the corrected dynamic cone tip resistance; According to the last data of dynamic cone tip resistance / [(v / d) / (v / d) ref ] β = The correction parameter β is calculated from the first data of the static cone tip resistance, where v is the velocity calculated by acceleration, d is the diameter of the probe at the cone tip, and the subscript ref is the reference value; Correct the other dynamic cone tip resistance according to the calculated correction parameter β to obtain the corrected other dynamic cone tip resistance: Corrected other dynamic cone tip resistance = other dynamic cone tip resistance / [(v / d) / (v / d)] ref ] β .

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