Method for determining dynamic and static bearing capacity of sediment based on marine static cone penetration test
By using a corrosion-resistant spherical probe and multiple penetration tests in a deep-sea environment, combined with sensor monitoring, the accuracy problem of deep-sea soft soil bearing capacity assessment was solved, improving equipment operation safety and efficiency, and reducing costs.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- CHINA MERCHANTS MARINE & OFFSHORE RES INST CO LTD
- Filing Date
- 2025-02-28
- Publication Date
- 2026-07-14
Smart Images
Figure CN120141562B_ABST
Abstract
Description
Technical Field
[0001] This application relates to the field of determining the mechanical properties of deep-sea soft soil, and more specifically, to a method for testing the dynamic and static bearing capacity of sediments based on marine static cone penetration testing. Background Technology
[0002] In the fields of offshore oil and gas, mineral resource development, and subsea engineering construction, the bearing capacity characteristics of deep-sea soft soil are one of the key parameters determining the construction of engineering facilities and the safe operation of equipment. With the deepening of deep-sea development, the demand for deep-sea mining and energy development is constantly increasing, especially for the extraction of mineral resources such as manganese nodules. In the process of deep-sea manganese nodule mining, mining trucks need to be placed on the seabed for ore collection operations, and their safety and operational stability are directly affected by the bearing capacity of the seabed surface soil. When operating in the deep sea, the mining trucks need to move and position themselves on the seabed; the bearing capacity characteristics of the surface soil affect not only the safety and stability of the mining truck equipment but also the efficiency of the entire ore collection process.
[0003] Furthermore, even when the subsea mining truck is not in operation, the bearing capacity of the seabed surface soil still affects it, impacting the truck's safety and stability during long-term static periods. During operation, the bearing capacity of the sediment changes with the truck's speed. This characteristic can cause settlement or uplift during truck movement, affecting the equipment's operational stability. Settlement or uplift issues make it difficult for the truck to maintain a stable operating posture, thus affecting operational efficiency and accuracy. It also exacerbates wear and tear on the truck and its system components under different operating conditions, significantly increasing maintenance and operating costs. Due to the complexity of the deep-sea environment and the limitations of traditional assessment methods, existing bearing capacity prediction methods alone cannot obtain accurate parameters suitable for deep-sea conditions. Therefore, developing a bearing capacity assessment technology based on deep-sea static cone penetration test data, and accurately testing and interpreting the bearing capacity characteristics of deep-sea surface soft soil, can not only improve the operational efficiency and safety of mining trucks in the deep-sea environment but also effectively reduce the costs of deep-sea mining and subsea engineering. The application of this technology will provide more reliable design basis and operational support for deep-sea mining equipment and other seabed engineering facilities, and help the efficient development and sustainable utilization of deep-sea resources. Summary of the Invention
[0004] To overcome the shortcomings of existing technologies, this application provides a method for testing the dynamic and static bearing capacity of sediments based on marine static cone penetration testing.
[0005] The static cone penetration test system of this application is equipped with a spherical probe with a cross-sectional area of 100 cm². This probe is specifically designed for deep-sea use, possessing corrosion resistance, pressure resistance, and low-temperature resistance to adapt to the high-pressure, high-salinity, and low-temperature environments of the deep sea. Furthermore, the probe integrates multiple sensors, including a penetration resistance sensor, a pore water pressure sensor, and an attitude sensor, enabling real-time monitoring of the probe's penetration resistance, pore water pressure, and device attitude. These sensors are connected to the penetration device, power supply, and data acquisition system to ensure rapid and accurate data recording and transmission. The equipment also features a multi-layered protective structure and a stabilization system to ensure long-term reliability in the deep-sea environment.
[0006] The specific testing method is as follows:
[0007] Step S1, Deployment, includes the installation and release of the static cone penetrometer (PCP). First, the PCP is connected to the geological winch, and all internal sensors are activated to ensure proper functioning. After activation, the PCP is lowered to the seabed using the geological winch. During lowering, the device monitors water depth, pressure, and position in real time to ensure stable positioning upon reaching the seabed. This step ensures the stability of the PCP, providing a reliable foundation for subsequent penetration testing.
[0008] Step S2, a single penetration test: After the static cone penetrometer stabilizes on the seabed, the penetration speed of the probe is set to 0.02 m / s via the deck unit to ensure that the probe can smoothly and uniformly enter the sediment layer, avoiding disturbance to the natural state of the sediment. After the probe penetrates to the predetermined depth, it is held still for 5 minutes to ensure stable contact between the soil and the probe, and to achieve ideal data acquisition accuracy. After the settling period, the probe is gradually retrieved to the seabed surface using a winch.
[0009] Step S3, secondary penetration test, mainly involves secondary penetration at a similar station to obtain the in-situ rate effect coefficient. The static cone penetrometer is raised 5 meters using a geological winch, and after ensuring the device's position is stable, a second penetration test is conducted. This time, the probe penetration speed is set to 0.05 m / s, and the penetration steps are repeated to collect penetration resistance data at different speeds. This test also maintains a 5-minute static rest period, after which the probe is retrieved again.
[0010] Step S4, Data Reading and Device Cleaning: After the test is completed, the device is retrieved onto the deck using a geological winch, and the test equipment is cleaned to remove sediment and other deposits. After cleaning, all acquired data, including penetration resistance, pore water pressure, and attitude parameters, are read from the data acquisition system to provide raw data support for data interpretation and analysis.
[0011] Step S5: Calculation and adjustment of the penetration angle. The penetration angle of the probe is calculated using data from the attitude sensor to ensure the validity of the data during the penetration test. When the probe's penetration angle exceeds 15°, the penetration step is repeated until the angle is less than 15° to improve data accuracy and reliability. The formula for calculating the penetration angle is as follows: (1)
[0012] in, It is the probe's penetration angle. and This refers to the rotation angles of the attitude sensor in two mutually perpendicular directions in the horizontal direction. This step ensures that the probe enters the soil at a near-vertical angle, avoiding measurement errors caused by probe tilt.
[0013] Optionally, it also includes:
[0014] Determination of the velocity effect coefficient: This application introduces the velocity effect coefficient. The following formula is used to characterize the effect of different penetration velocities on the bearing capacity properties of sediments:
[0015] (2)
[0016] in, This is the rate effect coefficient. The penetration resistance measured at a penetration velocity of 0.02 m / s. The penetration resistance measured at a penetration velocity of 0.05 m / s. The penetration velocity during the first penetration. This represents the penetration velocity during the second penetration.
[0017] The determination of undrained shear strength is achieved by calculating the in-situ undrained shear strength of the sediment. ,
[0018] Further assess the bearing capacity of the soil. The formula for calculating this parameter is:
[0019] (3)
[0020] in, The in-situ undrained shear strength of the sediment. This is the penetration resistance coefficient.
[0021] Determination of Static and Dynamic Bearing Capacity: This application provides calculation methods for static and dynamic bearing capacity to help evaluate the performance of sediments under different loads. Under static load, the static bearing capacity of the sediment is:
[0022] (4)
[0023] in, For the static bearing capacity of sediments, Let be the cross-sectional area of the probe. Under dynamic loads, such as when a mining truck travels on the seabed, the dynamic bearing capacity of the sediment is calculated using the following formula:
[0024] (5)
[0025] in, For the dynamic bearing capacity of sediments, The dynamic bearing capacity of the sediment at a certain velocity is to be calculated. The dynamic bearing capacity of the sediment at different velocities can be calculated according to formula (5).
[0026] The method for testing the dynamic and static bearing capacity of sediments based on marine static cone penetration testing provided in this application has the following advantages:
[0027] 1. Enhanced adaptability and reliability in deep-sea environments: This application employs a specially designed spherical probe and a high-pressure and corrosion-resistant design, enabling it to operate for extended periods in complex deep-sea environments, avoiding data distortion and equipment damage caused by environmental factors. Multiple sensors are equipped to monitor penetration resistance, pore water pressure, and probe attitude in real time, ensuring accurate measurements under various water depths and pressures, thus improving the system's adaptability.
[0028] 2. Improved data accuracy and consistency: Through precise penetration speed control and penetration angle monitoring, this application effectively reduces errors caused by probe tilt or speed fluctuations. The design of multiple penetrations and automatic penetration angle adjustment ensures data accuracy and consistency, making it particularly suitable for testing the mechanical properties of deep-sea soft soil. The obtained bearing capacity data is more reliable, providing a more credible data foundation for engineering applications.
[0029] 3. Addressing the impact of velocity effects and improving the applicability of results. By introducing the calculation of the velocity effect coefficient (λ), this application can correct for the influence of different penetration velocities on the test results. This innovative design ensures the applicability of the measured sediment undrained shear strength and dynamic bearing capacity under different velocity conditions, making it suitable for evaluating the impact of equipment on seabed sediments under dynamic loads, especially for the engineering needs of dynamic equipment such as deep-sea mining vehicles.
[0030] 4. Supports comprehensive assessment of static and dynamic bearing capacity, expanding its application scope. This application not only obtains the static bearing capacity of sediments but also provides a method for calculating dynamic bearing capacity, enabling the assessment of sediment response under mining truck movement or other dynamic loads. This method is particularly suitable for scenarios requiring comprehensive bearing capacity assessment, such as deep-sea mining operations, subsea pipeline and platform construction, providing comprehensive data support for subsea equipment design.
[0031] 5. Improved safety and economy of deep-sea operations: The high-precision bearing capacity data provided in this application can help optimize the selection and design of deep-sea equipment, reduce equipment damage and mining efficiency reduction caused by subsidence or uplift, thereby significantly reducing safety hazards and operating costs in deep-sea operations. This has significant economic and safety implications for equipment such as deep-sea mining vehicles and oil and gas platforms operating in deep-sea environments. Attached Figure Description
[0032] The above and / or additional aspects and advantages of this application will become apparent and readily understood from the description of the embodiments taken in conjunction with the following drawings, in which:
[0033] Figure 1 A schematic diagram of a static cone penetrometer used in this application for a method of testing the dynamic and static bearing capacity of sediments using marine static cone penetrometer testing;
[0034] Figure 2 A schematic flowchart illustrating the method for testing the dynamic and static bearing capacity of sediments based on marine static cone penetration testing provided in this application;
[0035] Figure 3 A comparison diagram of the static and dynamic bearing capacities of sediments based on the method of testing the static and dynamic bearing capacities of sediments using marine static cone penetration testing provided in this application. Detailed Implementation
[0036] To better understand the above-mentioned objectives, features, and advantages of this application, the application will be further described in detail below with reference to the accompanying drawings and specific embodiments. It should be noted that, unless otherwise specified, the embodiments and features described in these embodiments can be combined with each other.
[0037] Many specific details are set forth in the following description in order to provide a full understanding of this application. However, this application may also be implemented in other ways different from those described herein. Therefore, the scope of protection of this application is not limited to the specific embodiments disclosed below.
[0038] like Figure 1The diagram shows a static cone penetration test instrument provided in this application for testing the dynamic and static bearing capacity of sediments. This instrument is equipped with a spherical probe with a cross-sectional area of 100 cm². The probe is specifically designed for deep-sea use, possessing corrosion resistance, pressure resistance, and low-temperature resistance to adapt to the high-pressure, high-salinity, and low-temperature environments of the deep sea. Furthermore, the probe integrates multiple sensors, including a resistance sensor, a pore water pressure sensor (pore pressure sensor), and an attitude sensor, enabling real-time monitoring of the probe's penetration resistance, pore water pressure, and device attitude. These sensors are connected to the penetration device, power supply, and data acquisition device to ensure rapid and accurate data recording and transmission. The device also features a multi-layered protective structure and a stabilization system to ensure long-term reliability in the deep-sea environment.
[0039] Combination Figure 2 The specific steps of the method for testing the dynamic and static bearing capacity of sediments based on marine static cone penetration testing provided in this application are as follows:
[0040] The first step is to release the static cone penetrometer (PCP). This involves the installation and release of the PCP, first connecting it to the geological winch, and then activating all internal sensors to ensure proper functioning. After activation, the PCP is lowered to the seabed using the geological winch. During the lowering process, the device monitors water depth, pressure, and position parameters in real time to ensure stable positioning upon reaching the seabed. This step ensures the stability of the PCP, providing a reliable foundation for subsequent penetration testing.
[0041] The next step was a penetration test. After the static cone penetrometer stabilized on the seabed, the penetration velocity of the probe was set to 0.02 m / s via the deck unit to ensure that the probe could enter the sediment layer smoothly and uniformly, avoiding disturbance to the natural state of the sediment. After the probe reached the predetermined depth, it was held still for 5 minutes to ensure stable contact between the soil and the probe, and to achieve ideal data acquisition accuracy. After the settling period, the probe was gradually retrieved to the seabed surface using a winch.
[0042] A second penetration test was conducted at a similar location to obtain the in-situ rate effect coefficient. The static cone penetrometer was raised 5 meters using a geological winch, and after ensuring the device's position was stable, the penetration test was performed again. This time, the probe penetration speed was set to 0.05 m / s, and the penetration steps were repeated to collect penetration resistance data at different speeds. This test also included a 5-minute rest period before the probe was retrieved again.
[0043] After data acquisition and device cleaning, the device was retrieved onto the deck using a geological winch and cleaned to remove sediment and other deposits. Following cleaning, all acquired data, including penetration resistance, pore water pressure, and attitude parameters, were read from the data acquisition system, providing raw data support for data interpretation and analysis.
[0044] Penetration angle calculation and adjustment. The penetration angle of the probe is calculated using data from the attitude sensor to ensure the validity of the data during the penetration test. When the probe's penetration angle is greater than 15°, the penetration procedure is repeated until the angle is less than 15° to improve data accuracy and reliability. The formula for calculating the penetration angle is as follows: (1)
[0045] in, It is the probe's penetration angle. and This refers to the rotation angles of the attitude sensor in two mutually perpendicular directions in the horizontal direction. This step ensures that the probe enters the soil at a near-vertical angle, avoiding measurement errors caused by probe tilt.
[0046] Determination of the velocity effect coefficient: This application introduces the velocity effect coefficient. The following formula is used to characterize the effect of different penetration velocities on the bearing capacity properties of sediments:
[0047] (2)
[0048] in, This is the rate effect coefficient. The penetration resistance measured at a penetration velocity of 0.02 m / s. The penetration resistance measured at a penetration velocity of 0.05 m / s. The penetration velocity during the first penetration. This represents the penetration velocity during the second penetration.
[0049] The determination of undrained shear strength is achieved by calculating the in-situ undrained shear strength of the sediment. ,
[0050] Further assess the bearing capacity of the soil. The formula for calculating this parameter is:
[0051] (3)
[0052] in, The in-situ undrained shear strength of the sediment. This is the penetration resistance coefficient.
[0053] Determination of Static and Dynamic Bearing Capacity: This application provides calculation methods for static and dynamic bearing capacity to help evaluate the performance of sediments under different loads. Under static load, the static bearing capacity of the sediment is:
[0054] (4)
[0055] in, For the static bearing capacity of sediments, Let be the cross-sectional area of the probe. Under dynamic loads, such as when a mining truck travels on the seabed, the dynamic bearing capacity of the sediment is calculated using the following formula:
[0056] (5)
[0057] in, For the dynamic bearing capacity of sediments, The dynamic bearing capacity of the sediment at a certain velocity is to be calculated. The dynamic bearing capacity of the sediment at different velocities can be calculated according to formula (5).
[0058] Figure 3 As a computational example of this method, the difference between the static bearing capacity calculated by conventional static cone penetration testing and the dynamic bearing capacity calculated by this method was calculated. The test point in the figure is located in a sea area of the South China Sea. The blue line represents the bearing capacity measured by static cone penetration testing, the red line represents the bearing capacity characteristics at a mine car traveling speed of 0.6 m / s, and the black line represents the bearing capacity characteristics at a mine car traveling speed of 1 m / s. It can be seen that the higher the mine car traveling speed, the greater the bearing capacity, but the increase in bearing capacity decreases with increasing mine car traveling speed. This can be used to design a reasonable mine car traveling speed to ensure that the sediment bearing capacity is large enough and the mine car collection efficiency is high enough.
[0059] In the description of this application, the term "multiple" refers to two or more. Unless otherwise expressly defined, the terms "upper," "lower," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this application. The terms "connection," "installation," "fixing," etc., should be interpreted broadly. For example, "connection" can be a fixed connection, a detachable connection, or an integral connection; it can be a direct connection or an indirect connection through an intermediate medium. For those skilled in the art, the specific meaning of the above terms in this application can be understood according to the specific circumstances.
[0060] In the description of this specification, the terms "one embodiment," "some embodiments," "specific embodiment," etc., refer to a specific feature, structure, material, or characteristic described in connection with that embodiment or example, which is included in at least one embodiment or example of this application. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.
[0061] The above are merely preferred embodiments of this application and are not intended to limit this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application.
Claims
1. A method for testing the dynamic and static bearing capacity of sediments based on marine static cone penetration testing, characterized in that, The specific steps include: Step S1: Deployment; This mainly includes the installation and release of the static cone penetrometer. First, connect the static cone penetrometer to the geological winch, and start all the sensors inside the static cone penetrometer to ensure that the equipment functions normally. After the device is started, use the geological winch to lower the static cone penetrometer to the seabed. During the lowering process, the device monitors the water depth, pressure and position parameters in real time to ensure that the instrument is stably parked after reaching the seabed. This step ensures the stability of the static cone penetrometer and provides a reliable foundation for subsequent penetration tests. Step S2: Single Penetration Test; After the static cone penetrometer stabilizes on the seabed, the penetration speed of the probe is set to 0.02 m / s through the deck unit to ensure that the probe can enter the sediment layer smoothly and uniformly, avoiding disturbance to the natural state of the sediment. After the probe penetrates to the predetermined depth, it is kept still for 5 minutes to ensure stable contact between the soil and the probe, so that the data acquisition can achieve the ideal accuracy. After settling, the probe rod is gradually retrieved to the seabed surface using a winch, which can realize the parameters required for calculating the penetration resistance of seabed sediments. Step S3: Secondary Penetration Test; This mainly involves secondary penetration at similar stations to obtain the in-situ rate effect coefficient. The static cone penetrometer is raised 5 meters using a geological winch. After ensuring the device's position is stable, a second penetration test is conducted. This time, the probe penetration speed is set to 0.05 m / s. The penetration steps are repeated, and penetration resistance data at different speeds are collected. This test also maintains a 5-minute rest period before the probe is retrieved again. This step allows us to obtain the characteristics of penetration resistance changing with penetration speed under this environment at different penetration speeds, which is used to calculate the rate effect coefficient. This method overcomes the limitation of static cone penetrometer technology, which can only test static process parameters. Step S4: Data reading and device cleaning; After the test is completed, the device is retrieved to the deck using a geological winch and the test equipment is cleaned to remove sediment and other attachments. After cleaning, all acquired data, including penetration resistance, pore water pressure and attitude parameters, are read from the data acquisition system to provide raw data support for data interpretation and analysis. Step S5: Calculation and adjustment of penetration angle; Calculate the probe's penetration angle using data from the attitude sensor to ensure the validity of the data during the penetration test; When the probe's penetration angle is greater than 15°, repeat step 2 until the angle is less than 15° to improve data accuracy and reliability; The formula for calculating the penetration angle is as follows: (1); in, It is the probe's penetration angle. and This step involves rotating the sensor in two mutually perpendicular directions in the horizontal direction. This ensures that the probe enters the soil at a near-vertical angle, avoiding measurement errors caused by probe tilt. The method for testing the dynamic and static bearing capacity of sediments based on marine static cone penetration testing is characterized by the need to introduce a velocity effect coefficient. The following formula is used to characterize the effect of different penetration velocities on the bearing capacity properties of sediments: （2）； in, This is the rate effect coefficient. The penetration resistance measured at a penetration velocity of 0.02 m / s. The penetration resistance measured at a penetration velocity of 0.05 m / s. The penetration velocity during the first penetration. This represents the penetration velocity during the second penetration.
2. The method for testing the dynamic and static bearing capacity of sediments based on marine static cone penetration testing as described in claim 1, characterized in that, The bearing capacity characteristics of sediments require the use of undrained shear strength. The formula for undrained shear strength of sediments based on static cone penetration testing is as follows: （3）； in, The in-situ undrained shear strength of the sediment. This is the penetration resistance coefficient.
3. The method for testing the dynamic and static bearing capacity of sediments based on marine static cone penetration testing as described in claim 2, characterized in that, By determining the static and dynamic bearing capacities, and through the calculation methods for these capacities, we can help evaluate the performance of sediments under different loads. Under static loads, the static bearing capacity of the sediments is: （4）； in, For the static bearing capacity of sediments, This refers to the cross-sectional area of the probe; Under dynamic loads, such as when a mining truck travels on the seabed, the dynamic bearing capacity of sediments is calculated using the following formula: （5）； in, For the dynamic bearing capacity of sediments, To calculate the dynamic bearing capacity of sediments at a certain velocity, the dynamic bearing capacity of sediments at different velocities can be calculated using formula (5).
4. The method for testing the dynamic and static bearing capacity of sediments based on marine static cone penetration testing as described in claim 1, characterized in that, The static cone penetration test (SPT) consists of a penetration device, a power system, a data acquisition system, and a probe. The probe for the seabed static cone penetration test is a spherical probe with a cross-sectional area of 100 cm². Designed specifically for deep-sea use, this probe is corrosion-resistant, pressure-resistant, and low-temperature resistant to adapt to the high-pressure, high-salinity, and low-temperature deep-sea environment. The probe integrates multiple sensors, including a penetration resistance sensor, a pore water pressure sensor, and an attitude sensor, enabling real-time monitoring of the probe's penetration resistance, pore water pressure, and device attitude. These sensors are connected to the penetration device, power supply, and data acquisition system to ensure rapid and accurate data recording and transmission. The device also features a multi-layered protective structure and a stabilization system to ensure long-term reliability in the deep-sea environment.