Test system for determining strength parameters of marine shallow soft clay

Abstract

The invention provides a test system for determining strength parameters of marine shallow soft clay. The test system comprises a loading device, a simulation controller and a data processing module, an S-shaped tension and compression sensor, a floating joint, a tungsten steel probe rod and a probe are arranged above the n-shaped bracket, and a pore pressure sensor is arranged in the probe; the simulation controller is used for controlling the servo motor to rotate so as to drive the linear module to move up and down, so that the sensor base is driven to move up and down, and the excess pore water pressure value in the soil body at the position of the probe is measured; the system disclosed by the invention can accurately measure parameters such as pore pressure in a ship-based on-site environment, is portable, low in cost, high in automation degree and strong in stress-strain control compatibility, and can truly and reliably measure parameters such as strength, deformation and pore pressure of the marine soft clay.

Description

Technical Field

[0001] The present invention relates to the technical field of strength parameter measurement of marine shallow soft clay, and in particular to a test system for measuring strength parameters of marine shallow soft clay. Background Art

[0002] As land resources become increasingly scarce, humanity's exploration and utilization of the ocean continues to deepen, leading to the construction of numerous marine projects, such as offshore wind power, cross-sea bridges, ports, submarine tunnels, and deep-sea oil and gas platforms. The foundations of these projects often rest on shallow marine soft clay strata, characterized by high water content, a large porosity, strong compressibility, low strength, and poor permeability. In the marine environment, soft clay is subject to long-term dynamic loads such as waves, tides, and earthquakes, as well as the weight of the structures themselves. Its complex and variable mechanical properties make the interaction between shallow marine soft clay and structures extremely critical.

[0003] Accurately measuring the strength parameters of marine soft clay is fundamental to solving the aforementioned problems. Before designing offshore engineering foundations, a scientific understanding of the strength parameters of shallow marine soft clay is necessary to assess the foundation's bearing capacity and stability. Currently, although a number of traditional indoor and in-situ testing methods, such as triaxial testing, direct shear testing, and cross-plate testing, are available for determining the strength parameters of marine soft clay, these methods all have limitations. For example, indoor testing requires collecting undisturbed soil samples, which is difficult to obtain and prone to disturbances during transportation, leading to inaccurate test results. In-situ testing is relatively expensive to conduct offshore and is often limited by on-site water depth, sea conditions, limited equipment intelligence, and uncontrollable factors, resulting in significant errors. Therefore, developing a portable, multifunctional testing device that can be performed on a ship foundation is of great practical significance for accurately measuring the strength parameters of shallow marine soft clay and addressing practical issues in offshore engineering. Summary of the Invention

[0004] In view of the above technical problems, the technical solution adopted by the present invention is: According to the present application, a test system for measuring strength parameters of shallow marine soft clay is provided, the system comprising: A loading device, a simulation controller, and a data processing module; wherein the loading device includes a base and an n-shaped bracket; the n-shaped bracket is arranged on the base, and a soil sample holder is arranged on the inner side wall of the n-shaped bracket, and the soil sample holder is used to fix the soil sample to keep it vertical and stable; An S-type tension and compression sensor, a floating joint, a tungsten steel probe and a probe are arranged above the n-type bracket, and a pore pressure sensor is arranged in the probe; the tungsten steel probe penetrates the n-type bracket from the top, and a probe is arranged at one end of the tungsten steel probe that penetrates the n-type bracket for detecting the pore pressure of the soil sample; the other end is connected to the S-type tension and compression sensor through a floating joint; the S-type tension and compression sensor is connected to the linear module through the sensor base, and the linear module is connected to the AC servo motor transmission; the analog controller is used to control the rotation of the AC servo motor to drive the linear module up and down, thereby driving the sensor base up and down to measure the excess pore water pressure value in the soil at the probe position; The data processing module is used to perform the following steps: S100, calibrate the S-type tension and compression sensor and zero the probe; S200, obtaining loading control parameters corresponding to each preset loading mode; S300, sending a loading control parameter corresponding to a specified loading mode to an analog controller, so as to control the AC servo motor to operate in the specified loading mode through the analog controller; wherein the specified loading mode is any preset loading mode; S400: Obtain the excess pore water pressure value in the soil at the probe position under the specified loading mode.

[0005] Furthermore, the preset loading modes include: a unidirectional loading mode of displacement control, a reciprocating loading mode of displacement control, a unidirectional loading mode of stress control, and a reciprocating loading mode of stress control.

[0006] Furthermore, if the designated loading mode is a unidirectional loading mode of displacement control, step S300 includes the following steps: S310, obtaining first control parameters set by the analog controller; wherein the first control parameters include: acquisition frequency, initial motion direction, speed, and stop time; S311, controlling the AC servo motor to perform unidirectional loading under the first control parameter; S312, obtaining the resistance Q1 exerted on the probe and the excess pore water pressure value in the soil at the probe location.

[0007] Furthermore, if the designated loading mode is a reciprocating loading mode with displacement control, step S300 includes the following steps: S320, obtaining second control parameters set by the analog controller; wherein the second control parameters include: acquisition frequency, initial motion direction, speed, single cycle duration, and stop time corresponding to the reciprocating loading mode of the displacement control method; S321, controlling the AC servo motor to perform unidirectional loading under the second control parameter; S322, obtain the resistance Q2 experienced by the probe and the excess pore water pressure value in the soil at the probe location; the resistance experienced during the initial penetration is recorded as Q ini , the residual resistance Q of the soil sample finally reaches the reshaped state rem .

[0008] Furthermore, if the designated loading mode is a unidirectional loading mode of stress control, step S300 includes the following steps: S330, obtaining third control parameters set by the simulation controller; wherein the third control parameters include: an acquisition frequency, an initial movement direction, and a constant penetration force corresponding to a unidirectional loading mode of a stress control method; S331, when the probe displacement no longer increases under the constant penetration force, the test stops; S332, obtaining the displacement of the probe under the action of a constant penetration force and the excess pore water pressure value in the soil at the probe location.

[0009] Furthermore, if the designated loading mode is a stress-controlled reciprocating loading mode, step S300 includes the following steps: S340, obtaining the fourth control parameter set by the simulation controller; wherein the fourth control parameter includes: the acquisition frequency, the initial movement direction, the sine wave amplitude and the loading frequency corresponding to the reciprocating loading mode of the stress control method; wherein, when the initial movement direction is downward, the entire sine wave function is f ( t )=sin t , when the initial movement direction is upward, the entire sine wave function is f ( t )=-sin t ; t is time; S341, when the probe displacement no longer increases under the action of the sine wave, the test stops; S342, obtaining the displacement of the probe under the action of the sine wave and the excess pore water pressure value in the soil at the probe location.

[0010] Furthermore, step S400 includes the following steps: S410, calculate the undrained shear strength Su of the soil sample; where: ; Q is the probe resistance, A is the cross-sectional area of the probe, N t To correct the drag coefficient; S420, based on the upper limit solution of plasticity theory for N t Conduct research and obtain an upper limit solution for the surface friction coefficient ; Where, α is the friction angle between the probe surface and the soil; S430, determine the sensitivity of the soil sample ;in, s u-ini is the undrained shear strength of the original soil sample; S u-rem It is the undrained shear strength of the soil sample in the completely reshaped state.

[0011] Furthermore, the tungsten steel probe rod penetrates into the n-type bracket from the top of the n-type bracket through a linear bearing.

[0012] Furthermore, the analog controller is a PLC analog controller.

[0013] The present invention has at least the following beneficial effects: The test system for measuring the strength parameters of shallow marine soft clay of the present invention fixes the soil sample to maintain vertical stability by means of an N-shaped bracket and an inner wall soil sample holder arranged on a base, thereby avoiding disturbance of the soil sample; the high rigidity and low surface roughness of the tungsten steel probe reduce the influence of bending moment and friction; the analog controller controls the servo motor to drive the linear module to move, thereby achieving high-precision loading control and reducing interference from human factors; the calibration, zeroing and multiple loading modes of the data processing module can accurately measure parameters such as pore pressure in an on-site shipbase environment; the device is portable, low-cost, highly automated, and has strong stress-strain control compatibility, and can truly and reliably measure parameters such as strength, deformation, and pore pressure of marine soft clay, providing solid data support and scientific basis for marine engineering foundation design, construction plan formulation and long-term stability evaluation, effectively solving the shortcomings of existing technologies. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0015] Figure 1 A schematic diagram of the two-dimensional structure of a loading device provided in an embodiment of the present invention; Figure 2 A flowchart of the steps performed by the data processing module provided in an embodiment of the present invention; Figure 3 A schematic diagram of a unidirectional loading mode for displacement control provided by an embodiment of the present invention; Figure 4 A schematic diagram of a displacement-controlled reciprocating loading mode provided by an embodiment of the present invention; Figure 5 Schematic diagram of a unidirectional loading mode for stress control provided by an embodiment of the present invention Figure 6A schematic diagram of a stress-controlled reciprocating loading mode provided by an embodiment of the present invention; Explanation of symbols: 1. Base, 2. Soil sample holder, 3. Probe, 4. Pore pressure sensor, 5. Linear bearing, 6. Tungsten steel probe rod, 7. Floating joint, 8. S-type tension and compression sensor, 9. Sensor base, 10. Linear module, 11. AC servo motor. DETAILED DESCRIPTION

[0016] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without making any creative efforts shall fall within the scope of protection of the present invention.

[0017] It should be noted that, based on this disclosure, those skilled in the art will appreciate that an aspect described herein can be implemented independently of any other aspect, and that two or more of these aspects can be combined in various ways. For example, any number of the aspects described herein can be used to implement an apparatus and / or practice a method. In addition, other structures and / or functionalities other than one or more of the aspects described herein can be used to implement such an apparatus and / or practice such a method.

[0018] The following is an introduction to the test system for measuring the strength parameters of shallow marine soft clay. The test system for measuring the strength parameters of shallow marine soft clay may include: a loading device, a simulation controller and a data processing module; Figure 1 As shown, the loading device includes a base 1 and an N-shaped bracket; the N-shaped bracket is arranged on the base 1, and a soil sample holder 2 is provided on the inner side wall of the N-shaped bracket, and the soil sample holder 2 is used to fix the soil sample to keep it vertical and stable.

[0019] In this embodiment, the n-shaped bracket is set on the base, and the soil sample holder is installed on the inner wall to provide a soil sample fixing space to prevent the soil sample from tilting or sliding during the test, thereby solving the problem of soil sample transportation disturbance in traditional indoor tests.

[0020] An S-type tension and compression sensor 8, a floating joint 7, a tungsten steel probe rod 6 and a probe 3 are arranged above the n-type bracket, and a pore pressure sensor 4 is arranged in the probe 3; the tungsten steel probe rod 6 penetrates into the n-type bracket from the top of the n-type bracket, and a probe 3 is arranged at one end of the tungsten steel probe rod 6 penetrating into the n-type bracket for detecting the pore pressure of the soil sample; the other end is connected to the S-type tension and compression sensor 8 through the floating joint 7; the S-type tension and compression sensor 8 is connected to the linear module 10 through the sensor base 9, and the linear module 10 is connected to the AC servo motor 11 for transmission; the analog controller is used to control the rotation of the AC servo motor 11 to drive the linear module 10 to move up and down, thereby driving the sensor base 9 to move up and down, so as to measure the excess pore water pressure value in the soil at the position of the probe 3.

[0021] Furthermore, the tungsten steel probe rod 6 passes through the n-type bracket from the top of the n-type bracket through the linear bearing 5, and the linear bearing 5 is detachable; it can reduce the direct shear with the tungsten steel probe rod 6 and ensure the longitudinal movement trajectory of the tungsten steel probe rod 6.

[0022] One end of the tungsten steel probe rod 6 passes through the top of the n-type bracket, and a pore pressure sensor probe is installed at the end. The probe has an integrated micro pore pressure sensor embedded in it, with a diameter of 2.54mm and wireless data transmission. The other end is connected to an S-type tension and compression sensor through a floating joint, with a range of 10kg and an accuracy of 0.01g, to measure the penetration / extraction resistance.

[0023] The tungsten steel probe has the characteristics of high rigidity and low surface roughness, which reduces the interference of bending moment and friction on the measurement results; the floating joint can keep the probe vertical, ensure the accurate penetration direction, and avoid human operation errors.

[0024] The floating joint keeps the probe rod vertical, ensuring accurate penetration direction and avoiding human operation errors.

[0025] The S-shaped tension and compression sensor is connected to a linear module via a sensor base. The linear module is driven by an AC servo motor, which features precise speed control, rapid response, and feedback regulation. This hardware connection enables precise up and down movement of the probe rod with a displacement accuracy of 0.01mm. It supports both unidirectional loading (constant rate or force) and reciprocating loading (cyclic variable frequency force mode).

[0026] Set the loading mode: displacement control / stress control, rate, stress magnitude, cycle time and number, and movement direction; the analog controller can be a PLC analog controller, which can control the AC servo motor with high precision.

[0027] Example: In displacement control mode, set the rate to 1 mm / s and the dwell time to 100 s; in stress control mode, set the constant penetration force to 3 kg.

[0028] Technical effect: Replaces the manual operation of traditional in-situ tests, realizes automatic loading, and reduces interference from human factors.

[0029] The entire loading control system includes a PLC simulation controller and a loading system, and the loading system includes the loading device in the above embodiment.

[0030] The data acquisition system includes a portable external power supply, a data reader, a communication converter and data acquisition software for data collection and analysis.

[0031] The data processing module is used to perform Figure 2 Steps shown: S100, calibrate the S-type tension and compression sensor and zero the probe.

[0032] Furthermore, calibrating the S-type tension and compression sensor may include the following steps: S110, graded loading, load the standard weights onto the sensor in ascending order, and wait 1-3 minutes after each loading to allow the sensor output signal to stabilize.

[0033] S111: The loading process should be as slow and steady as possible, avoiding shock and vibration. Continue loading weights until the sensor reaches its full capacity, recording the sensor output value for each weight added.

[0034] S112: Analyze the linear relationship between the recorded weight (input value) and the sensor output value. The test can be started when the linear correlation coefficient R²>0.99 is met.

[0035] Through the above steps, the sensor measurement accuracy can be ensured and data distortion caused by equipment errors can be avoided.

[0036] Furthermore, zeroing the probe may include the following steps: S120, use absorbent paper to wipe off excess moisture on the surface of the soil sample to prevent water from entering the soil along with the probe and increasing the moisture content of the soil in the action area, thereby avoiding inaccurate measurement of the undrained shear strength.

[0037] S121, place the soil sample directly below the probe, adjust the probe height to be close to the upper surface of the soil sample, and reset the tension and compression sensors.

[0038] Through the above steps, the initial stress and moisture interference are eliminated, the accuracy of the initial test conditions is ensured, and the accuracy of the measured data is improved.

[0039] S200: Obtain loading control parameters corresponding to each preset loading mode.

[0040] In this embodiment, the loading control parameters may include: a constant rate, such as 1 mm / s; a movement time, such as 100 s; or a number of cycles, such as 15 times.

[0041] Stress control includes: setting a constant penetration force, such as 3kg, or sinusoidal loading parameters, such as amplitude and frequency.

[0042] Parameter source: pre-set according to the test objectives, such as determining the shear strength at different rates and the change in pore pressure under cyclic loading.

[0043] S300 , sending a loading control parameter corresponding to a designated loading mode to an analog controller, so as to control the AC servo motor to operate in the designated loading mode through the analog controller; wherein the designated loading mode is any preset loading mode.

[0044] In this embodiment, the execution logic of step S300 is as follows: The analog controller transmits loading control parameters to the AC servo motor, which drives the linear module to move the probe. For example, during unidirectional loading (displacement control), the probe penetrates the soil at a constant rate until the set time is reached. During reciprocating loading (stress control), the probe cyclically moves according to a sinusoidal pattern. Automated control enables multi-mode loading, compatibility with tests under varying stress conditions, and reduces manual error.

[0045] Furthermore, the preset loading modes include: a unidirectional loading mode of displacement control, a reciprocating loading mode of displacement control, a unidirectional loading mode of stress control, and a reciprocating loading mode of stress control.

[0046] The system in this embodiment can realize functions including two motion modes: unidirectional loading and reciprocating loading mode; and two control modes: displacement control and stress control mode. The details are as follows: Unidirectional loading refers to the measurement of the penetration resistance and displacement response behavior of the probe under the action of a constant rate (causing the probe to produce a fixed displacement per unit time) or a constant force (always maintaining a constant force on the soil below the probe) from the initial point to the final point.

[0047] Reciprocating loading refers to a cyclic loading pattern in which a specific loading state is periodically alternating. Starting from an initial state, a variable frequency force is applied at a specific loading rate or sinusoidal loading path until the target state is reached. Unloading is then reversed at the same rate or along a predetermined unloading path until the initial state is returned. This loading and unloading process is then repeated. Throughout the loading cycle, the magnitude and direction of the load alternate, but the loading pattern remains consistent from cycle to cycle, preventing any other loading patterns from occurring.

[0048] Furthermore, if the designated loading mode is a unidirectional loading mode of displacement control, step S300 includes the following steps: S310, obtaining first control parameters set by the analog controller; wherein the first control parameters include: acquisition frequency, initial motion direction, speed and stop time.

[0049] S311, controlling the AC servo motor to perform unidirectional loading under a first control parameter.

[0050] S312, obtaining the resistance Q1 exerted on the probe and the excess pore water pressure value in the soil at the probe location.

[0051] In this embodiment, before the test, the loading mode can be manually set to displacement control, and then the movement can be continued downward or upward at a constant rate. The movement rate, movement direction, movement time, and stop time can be manually set. The details are as follows: a) Start the PLC simulation controller and data acquisition software. Set the acquisition frequency in the data acquisition software. Set the loading mode to displacement control and the initial motion direction to up or down in the PLC simulation controller.

[0052] b) Set the rate and stop time on the analog controller.

[0053] c) Enable unidirectional loading and click the Start button.

[0054] d) When the test reaches the stop time, the start button automatically turns off.

[0055] e) Record the resistance of the probe as Q1, in kN. The excess pore water pressure in the soil near the probe is u T1 , unit is kPa. Q1 and u T Used to calculate the undrained shear strength of soil.

[0056] Example 1: Figure 3 As shown in the figure, before the test begins, manually click Start to set the movement direction, speed and time, and the entire process of constant speed movement of 100 mm can be obtained.

[0057] Furthermore, if the designated loading mode is a reciprocating loading mode with displacement control, step S300 includes the following steps: S320, obtaining second control parameters set by the analog controller; wherein the second control parameters include: acquisition frequency, initial motion direction, speed, single cycle duration, and stop time corresponding to the reciprocating loading mode of the displacement control method; S321, controlling the AC servo motor to perform unidirectional loading under the second control parameter; S322, obtain the resistance Q2 experienced by the probe and the excess pore water pressure value in the soil at the probe location; the resistance experienced during the initial penetration is recorded as Q ini , the residual resistance Q of the soil sample finally reaches the reshaped state rem .

[0058] In this embodiment, the reciprocating loading mode starts with a constant speed upward or downward movement, stops after reaching the set single cycle time, starts moving in the opposite direction, and stops after reaching the same cycle time. This up and down movement is called a complete cycle. The details are as follows: a) Start the PLC simulation controller and data acquisition software, set the acquisition frequency in the data acquisition software, and set the loading mode to displacement control and the initial motion direction in the PLC simulation controller.

[0059] b) Set the rate, single cycle duration and number of cycles on the simulation controller.

[0060] c) Start reciprocating loading and click the Start button.

[0061] d) After the test reaches the set number of cycles, the start button automatically turns off.

[0062] e) Record the resistance of the probe as Q, of which the resistance of the initial penetration is Q ini , the residual resistance Q of the soil sample finally reaches the reshaped state rem The measured excess pore water pressure value in the soil near the probe is uT.

[0063] Example 2: Figure 4 As shown, before the test, the manual initial movement direction is set upward, the loading rate is manually adjusted to 0.2 mm / s, the single cycle time is 25 s, the number of cycles is 15 times, that is, the single path is 5 mm, and "1 point-2 point-1 point" is a loading cycle. The loading stops automatically after completing 15 loading cycles.

[0064] Furthermore, if the designated loading mode is a unidirectional loading mode of stress control, step S300 includes the following steps: S330, obtaining third control parameters set by the simulation controller; wherein the third control parameters include: acquisition frequency, initial movement direction, and constant penetration force corresponding to the unidirectional loading mode of the stress control method.

[0065] S331: When the probe displacement no longer increases under the constant penetration force, the test stops.

[0066] S332, obtaining the displacement of the probe under the action of a constant penetration force and the excess pore water pressure value in the soil at the probe location.

[0067] In this embodiment, before the test, the loading mode can be manually set to stress control, and the movement direction and penetration resistance can be set. The probe is moved in a certain loading direction with a constant penetration resistance, and the displacement change pattern of the entire process is measured by the displacement sensor. The details are as follows: a) Start the PLC simulation controller and data acquisition software, set the acquisition frequency in the data acquisition software, and set the loading mode to stress control and the initial motion direction in the PLC simulation controller.

[0068] b) Set a constant penetration force on the simulation controller.

[0069] c) Enable unidirectional loading and click the Start button.

[0070] d) The test stops when the probe displacement no longer increases under the action of the constant penetration force.

[0071] e) Record the probe displacement s under the constant penetration force T The measured excess pore water pressure in the soil near the probe is u T Example 3: Figure 5 As shown in the figure, the movement direction is set to downward before the test, and the constant penetration resistance F=3kg. Since there is soil under the probe, the soil will be compressed harder and harder under the penetration resistance. Therefore, the acceleration will change rapidly in the early stage of this process. As the soil is gradually compacted, it will reach stability at a certain depth. Figure 5 Point 1 in the chart is the maximum penetration depth.

[0072] Furthermore, if the designated loading mode is a stress-controlled reciprocating loading mode, step S300 includes the following steps: S340, obtaining the fourth control parameter set by the simulation controller; wherein the fourth control parameter includes: the acquisition frequency, the initial movement direction, the sine wave amplitude and the loading frequency corresponding to the reciprocating loading mode of the stress control method; wherein, when the initial movement direction is downward, the entire sine wave function is f ( t )=sin t , when the initial movement direction is upward, the entire sine wave function is f ( t )=-sin t ; t is time.

[0073] S341: When the probe displacement no longer increases under the action of the sine wave, the test stops.

[0074] S342, obtaining the displacement of the probe under the action of the sine wave and the excess pore water pressure value in the soil at the probe location.

[0075] In this embodiment, the loading mode can be manually set to stress control before the test, and the initial movement direction, sine wave amplitude, and loading frequency f can be set. For example, when the initial movement direction is downward, the entire sine wave function is f(t)=sint, and when the initial movement direction is upward, the entire sine wave function is f(t)=-sint. The inverse of the loading frequency (1 / f) is the loading time of each cycle. The motion trajectory of the probe can be monitored in real time through the displacement sensor during the entire process. The details are as follows: a) Start the PLC simulation controller and data acquisition software, set the acquisition frequency in the data acquisition software, and set the loading mode to stress control and "initial motion direction" in the PLC simulation controller.

[0076] b) Set the sine wave amplitude and loading frequency on the analog controller.

[0077] c) Start reciprocating loading and click the Start button.

[0078] d) The test stops when the probe displacement no longer increases under the action of the sine wave.

[0079] e) Record the displacement s of the probe under the action of the sine wave T The measured excess pore water pressure in the soil near the probe is u T .

[0080] Example 4: Figure 6 As shown in the figure, before the test, the loading mode was manually set to stress control, the initial movement direction was upward, the sine wave amplitude was 1kg, the loading frequency was 0.1, and each cycle time was 10s. Since the compressive strength of the soil is always greater than the tensile strength, the upward displacement in each cycle is always greater than the downward displacement, that is, the movement trajectory of the first two cycles is as follows Figure 6 The display shows 1 o'clock → 2 o'clock → 3 o'clock → 4 o'clock → 5 o'clock. Click Stop to stop automatically.

[0081] S400: Obtain the excess pore water pressure value in the soil at the probe position under the specified loading mode to determine the sensitivity of the soil sample.

[0082] Furthermore, step S400 includes the following steps: S410, calculate the undrained shear strength Su of the soil sample; where: ; Q is the probe resistance, A is the cross-sectional area of the probe, N t To correct the drag coefficient.

[0083] S420, based on the upper limit solution of plasticity theory for N t Conduct research and obtain an upper limit solution for the surface friction coefficient .

[0084] S430, determine the sensitivity of the soil sample ;in, s u-ini is the undrained shear strength of the original soil sample; S u-rem It is the undrained shear strength of the soil sample in the completely reshaped state.

[0085] In this embodiment, the principle of the full-flow penetration test method is based on the full-flow plasticity theory. During the penetration of the probe, the surrounding soil undergoes shear failure. After plastic flow forms near the probe, a more accurate plasticity theory solution can be obtained. The undrained shear strength of the soil can be calculated using the following formula: S u : (1) In formula (1), Q The probe resistance measured by the sensor is based on the initial penetration Q ini and reshape the residual resistance Q rem The shear strength of the initial penetration into soft clay can be obtained S u-ini and residual strength S u-rem , A is the cross-sectional area of the probe, in m 2 , N t In order to modify the resistance coefficient, the upper limit solution of plasticity theory is used to N t The study yielded an upper limit solution for the surface friction coefficient: (2) Among them, α is the friction angle between the probe surface and the soil, which reflects the roughness of the probe surface; N t The range is 9.14~11.86. It is usually recommended to polish or sandblast the probe surface. N t The recommended value is 10.5. S t It should be calculated as follows: (3) Where: S t is the sensitivity of the soil; s u-ini is the undrained shear strength of the original soil (kPa); S u-rem is the undrained shear strength of the soil in the fully remolded state (kPa).

[0086] The test system for measuring the strength parameters of shallow marine soft clay of this embodiment fixes the soil sample to maintain vertical stability by means of an N-shaped bracket and an inner wall soil sample holder provided on a base, thereby avoiding disturbance of the soil sample. The high rigidity and low surface roughness of the tungsten steel probe reduce the influence of bending moment and friction. The analog controller controls the AC servo motor to drive the linear module to achieve high-precision loading control and reduce interference from human factors. The calibration, zeroing and multiple loading modes of the data processing module can accurately measure parameters such as pore pressure in an on-site ship-based environment. The device is portable, low-cost, highly automated, and has strong compatibility with stress-strain control. It can truly and reliably measure parameters such as strength, deformation, and pore pressure of marine soft clay, providing solid data support and scientific basis for marine engineering foundation design, construction plan formulation and long-term stability assessment, effectively addressing the shortcomings of existing technologies.

[0087] Furthermore, although the steps of the method of the present disclosure are described in a particular order in the accompanying drawings, this does not require or imply that the steps must be performed in this particular order, or that all steps shown must be performed to achieve the desired results. Additionally or alternatively, some steps may be omitted, multiple steps may be combined into one step, and / or one step may be decomposed into multiple steps.

[0088] Although some specific embodiments of the present invention have been described in detail by way of examples, it should be understood by those skilled in the art that the above examples are for illustration only and are not intended to limit the scope of the present invention. It should also be understood by those skilled in the art that various modifications may be made to the embodiments without departing from the scope and spirit of the present invention.

Claims

1. A test system for measuring strength parameters of shallow marine soft clay, characterized in that: The system includes: a loading device, a simulation controller and a data processing module; wherein the loading device includes a base and an n-shaped bracket; the n-shaped bracket is arranged on the base, and a soil sample holder is arranged on the inner side wall of the n-shaped bracket, and the soil sample holder is used to fix the soil sample to keep it vertical and stable; An S-type tension and compression sensor, a floating joint, a tungsten steel probe and a probe are arranged above the n-type bracket, and a pore pressure sensor is arranged in the probe; the tungsten steel probe penetrates the n-type bracket from the top, and a probe is arranged at one end of the tungsten steel probe that penetrates the n-type bracket for detecting the pore pressure of the soil sample; the other end is connected to the S-type tension and compression sensor through a floating joint; the S-type tension and compression sensor is connected to the linear module through the sensor base, and the linear module is connected to the AC servo motor transmission; the analog controller is used to control the rotation of the servo motor to drive the linear module up and down, thereby driving the sensor base up and down to measure the excess pore water pressure value in the soil at the probe position; The data processing module is used to perform the following steps: S100, calibrate the S-type tension and compression sensor and zero the probe; S200, obtaining loading control parameters corresponding to each preset loading mode; S300, sending a loading control parameter corresponding to a specified loading mode to an analog controller, so as to control the AC servo motor to operate in the specified loading mode through the analog controller; wherein the specified loading mode is any preset loading mode; S400: Obtain the excess pore water pressure value in the soil at the probe position under the specified loading mode to determine the sensitivity of the soil sample.

2. The test system for measuring strength parameters of shallow marine soft clay according to claim 1, characterized in that: The preset loading modes include: a unidirectional loading mode of displacement control, a reciprocating loading mode of displacement control, a unidirectional loading mode of stress control, and a reciprocating loading mode of stress control.

3. The test system for measuring strength parameters of shallow marine soft clay according to claim 2, characterized in that: If the designated loading mode is a unidirectional loading mode with displacement control, step S300 includes the following steps: S310, obtaining first control parameters set by the analog controller; wherein the first control parameters include: acquisition frequency, initial motion direction, speed, and stop time; S311, controlling the AC servo motor to perform unidirectional loading under the first control parameter; S312, obtaining the resistance Q1 exerted on the probe and the excess pore water pressure value in the soil at the probe location.

4. The test system for measuring strength parameters of shallow marine soft clay according to claim 2, characterized in that: If the designated loading mode is a reciprocating loading mode with displacement control, step S300 includes the following steps: S320, obtaining second control parameters set by the analog controller; wherein the second control parameters include: acquisition frequency, initial motion direction, speed, single cycle duration, and stop time corresponding to the reciprocating loading mode of the displacement control method; S321, controlling the AC servo motor to perform unidirectional loading under the second control parameter; S322, obtain the resistance Q2 experienced by the probe and the excess pore water pressure value in the soil at the probe location; the resistance experienced during the initial penetration is recorded as Q ini , the residual resistance Q of the soil sample finally reaches the reshaped state rem .

5. The test system for measuring strength parameters of shallow marine soft clay according to claim 2, characterized in that: If the designated loading mode is a unidirectional loading mode of stress control, step S300 includes the following steps: S330, obtaining third control parameters set by the simulation controller; wherein the third control parameters include: an acquisition frequency, an initial movement direction, and a constant penetration force corresponding to a unidirectional loading mode of a stress control method; S331, when the probe displacement no longer increases under the constant penetration force, the test stops; S332, obtaining the displacement of the probe under the action of a constant penetration force and the excess pore water pressure value in the soil at the probe location.

6. The test system for measuring strength parameters of shallow marine soft clay according to claim 2, characterized in that: If the designated loading mode is a stress-controlled reciprocating loading mode, step S300 includes the following steps: S340, obtaining the fourth control parameter set by the simulation controller; wherein the fourth control parameter includes: the acquisition frequency, the initial movement direction, the sine wave amplitude and the loading frequency corresponding to the reciprocating loading mode of the stress control method; wherein, when the initial movement direction is downward, the entire sine wave function is f ( t )=sin t , when the initial movement direction is upward, the entire sine wave function is f ( t )=-sin t ; t is time; S341, when the probe displacement no longer increases under the action of the sine wave, the test stops; S342, obtaining the displacement of the probe under the action of the sine wave and the excess pore water pressure value in the soil at the probe location.

7. The test system for measuring strength parameters of shallow marine soft clay according to claim 1, characterized in that: Step S400 includes the following steps: S410, calculate the undrained shear strength Su of the soil sample; where: ; Q is the probe resistance, A is the cross-sectional area of the probe, N t To correct the drag coefficient; S420, based on the upper limit solution of plasticity theory for N t Conduct research and obtain an upper limit solution for the surface friction coefficient ; Where, α is the friction angle between the probe surface and the soil; S430, determine the sensitivity of the soil sample ;in, s u-ini is the undrained shear strength of the original soil sample; S u-rem It is the undrained shear strength of the soil sample in the completely reshaped state.

8. The test system for measuring strength parameters of shallow marine soft clay according to claim 1, characterized in that: The tungsten steel probe rod passes through the n-type bracket from the top of the n-type bracket through a linear bearing.

9. The test system for measuring strength parameters of shallow marine soft clay according to claim 1, characterized in that: The analog controller is a PLC analog controller.

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