Testing device and method for studying upward pulling of suction bucket during installation based on static sounding

Abstract

The invention provides a static sounding-based test device and a static sounding-based test method for researching mounting and upward pulling of a suction bucket, and aims to research mounting and upward pulling processes of the suction bucket. The test device comprises a model box, a sample preparation system, an in-situ test system and a suction bucket installation test system. The model box simulates a marine environment and accommodates sandy soil samples with different relative densities. The sample preparation system consists of a crane and a sand rain device and is responsible for preparing sand; the in-situ testing system comprises a static sounding device, a flat spade side expansion penetration device and a hydraulic device and is used for obtaining in-situ mechanical parameters of the soil body. In addition, the suction bucket installation test system simulates the negative pressure penetration process of the suction bucket foundation and comprises a suction bucket model and a negative pressure adjusting system. According to the test device, CPT and DMT data are collected through in-situ testing, the penetration resistance of the suction bucket foundation is jointly estimated, a scientific basis is provided for design and construction of the suction bucket foundation, and high precision and stability of the test are ensured.

Description

Technical Field

[0001] The invention relates to the technical field of marine structural engineering, and in particular to a test device and method for studying the installation and pulling-out of a suction bucket based on static penetration. Background Art

[0002] With the development of offshore wind power, suction bucket foundation has gradually become an important part of marine structural engineering. Suction bucket foundation has been widely used in the construction of offshore wind farms due to its advantages such as simple construction, low cost and environmental friendliness. However, there are many problems in the current test process of suction bucket, including the following aspects:

[0003] The test setup lacks uniformity and standardization: The current suction bucket test design is relatively scattered, and usually does not provide detailed instructions on the sample preparation process, the parameters of the sand rainer, and the calculation method of the sand density. This leads to poor comparability and repeatability of the test results, making it difficult to form a unified test standard.

[0004] Sufficient in-situ testing methods have not yet been introduced: The cone penetration test (CPT) method is currently often used in marine engineering to obtain seabed soil information. The continuous soil layer mechanical data provided by CPT plays an important role in the bearing capacity calculation of the suction bucket foundation and the bearing capacity assessment of the soil, but it is rarely integrated in domestic model test equipment, mainly because the CPT equipment needs to be equipped with more supporting equipment. In addition, the flat shovel lateral expansion test (DMT) can measure the friction angle and deformation modulus of the soil, complementing CPT and providing more comprehensive soil mechanical properties data. However, there is currently no device that integrates the two in-situ test methods of CPT and DMT into the same test system, which limits the comprehensive and accurate assessment of the mechanical properties of the soil.

[0005] It should be noted that the information disclosed in the above background technology section is only used for understanding the background of the present application, and therefore may include information that does not constitute prior art known to ordinary technicians in the field. Summary of the invention

[0006] The main purpose of the present invention is to overcome the defects existing in the above-mentioned background technology and to provide a test device and method for studying the installation and pulling-out of a suction bucket based on static penetration.

[0007] To achieve the above object, the present invention adopts the following technical solutions:

[0008] A test device based on static penetration testing for studying the installation and pulling-up of a suction bucket, comprising:

[0009] A model box, used for simulating marine environmental conditions, containing sand and soil obtained by sample preparation to provide a simulated environment for the suction bucket foundation;

[0010] A sample preparation system, used for preparing sand samples of different relative densities, comprising:

[0011] The crane is used to control the height of the sand rainer and the sand falling process to achieve uniform sand falling;

[0012] Sand rain device, used to control the falling of sand and soil to achieve the preparation of sand samples with expected relative density;

[0013] An in-situ testing system is used to obtain in-situ mechanical parameters of soil, and the in-situ testing system comprises:

[0014] Static cone penetration device, used to measure the penetration resistance of soil;

[0015] Flat shovel lateral expansion penetration device, used to measure the lateral pressure and deformation modulus of soil;

[0016] A hydraulic device is used to drive the penetration device to achieve the penetration and recovery of the probe;

[0017] The suction bucket installation test system is used to simulate the negative pressure penetration process of the suction bucket foundation. The suction bucket installation test system includes:

[0018] Suction bucket model system, used to simulate the installation and pull-up process of the actual suction bucket;

[0019] The negative pressure regulating system is used to control the negative pressure penetration process and simulate the negative pressure environment when the suction bucket is sinking and pulling out by adjusting the negative pressure value.

[0020] Further: the model box is provided with:

[0021] The permeable layer is formed by laying gravel and geotextile in sequence;

[0022] The inlet and outlet valves are located at the bottom of the model box and are used to inject water from the bottom to saturate the sand and soil so that the water level is higher than the geotextile position;

[0023] Pore ​​pressure sensor, pre-buried in sand, used to measure the change of soil pressure;

[0024] Bracket, used to fix the pore pressure sensor and ensure its correct position during sand falling.

[0025] Further: the sample preparation system comprises:

[0026] The crane is installed on the operating table and is equipped with a digital frequency conversion motor on the top. The motor is connected to the pulley system through a wire rope to control the height of the sand rainer and the sand falling process;

[0027] A sand rain device, which includes a cylindrical upper part and a conical funnel lower part, is used to control and adjust the sand falling height to achieve the expected relative density of sand and soil;

[0028] The switch is used to control the release and stop of sand in the sand rainer to achieve precise sand falling control.

[0029] Further: the sand rain device comprises:

[0030] A round pipe, connected to the tail of the funnel, is used to guide the flow of sand;

[0031] A flexible hose is arranged at the end of the round tube to facilitate the flexible output of sand and soil;

[0032] The bottom of the circular tube is provided with a slit for controlling the release of sand and soil;

[0033] The switch comprises a switch steel sheet which is arranged at the cut and can be pulled out or inserted to control the flow of sand and soil.

[0034] Further: the in-situ testing system comprises:

[0035] A static penetration device, comprising a static penetration probe and a slotted screw, wherein the probe is connected to the screw and is placed in a penetration hole of a beam frame, and is used for static penetration testing of soil;

[0036] A flat shovel lateral expansion penetration device includes a flat shovel probe, a nitrogen bottle, a pressure reducing valve and a gas-electric pipeline. The probe is connected to a slotted screw and is externally connected to a nitrogen bottle and a pressure reducing valve through a gas-electric pipeline to perform a lateral expansion test on a soil body.

[0037] The hydraulic device comprises a hydraulic pump, a hydraulic regulating valve, a hydraulic oil pipe and a hydraulic jack. The hydraulic pump is connected to the jack through an oil pipe and is controlled by a regulating valve to drive the penetration and recovery of the penetration device.

[0038] Further: the suction bucket model system includes:

[0039] The suction bucket foundation adopts a skirted or non-skirted design. The non-skirted suction bucket is made of steel with a bottom and a cover, and the skirted suction bucket has a skirt structure added to the outer ring of the bucket wall;

[0040] Soil pressure sensor, installed on the side wall of the suction bucket, used to measure soil pressure;

[0041] The water pumping holes are symmetrically arranged on the surface of the suction bucket base cover plate and are used to connect the water pumping pipe to realize the water pumping function in the bucket;

[0042] Negative pore pressure sensor, installed on the surface of the suction bucket base cover, is used to measure the negative pressure in the bucket;

[0043] The skirt drainage hole is set at the center of the skirt of the skirt barrel foundation to drain water during installation and reduce penetration resistance;

[0044] A vertical screw connects the suction bucket base cover plate and the force sensor to transmit the force of the suction bucket;

[0045] The force sensor is connected to the vertical screw and the crane to measure the penetration and pull-out force of the suction bucket.

[0046] Further: the negative pressure regulating system comprises:

[0047] Vacuum pump, used to generate and regulate negative pressure;

[0048] A solid-liquid separation device, used in conjunction with a vacuum pump, comprises a vacuum cylinder, a double-head water inlet, a water outlet and a negative pressure regulating valve;

[0049] Vacuum cylinder, used to store water, air and sand sucked from the suction bucket;

[0050] The double-head water inlet is located on the upper part of the vacuum cylinder and is used in conjunction with the negative pressure regulating valve to control the negative pressure value;

[0051] A water outlet is provided at the bottom of the vacuum cylinder and is used to discharge the solid-liquid mixture in the vacuum cylinder;

[0052] The water extraction pipe connects the vacuum cylinder and the water extraction hole of the suction bucket to realize the negative pressure extraction process.

[0053] A method for performing a suction bucket installation pull-up test using the test device comprises the following steps:

[0054] S1. Prepare sand samples: lay a permeable layer in the model box and inject water to saturate the sand. Control the height and path of the falling sand through a sand rain device to prepare sand samples with different relative densities, and pre-embed a pore pressure sensor in the sand.

[0055] S2. In-situ testing: The hydraulic system drives the probe into the sand and soil to continuously collect static penetration test (CPT) data and flat shovel side expansion (DMT) data at a set depth to obtain the in-situ mechanical parameters of the soil.

[0056] S3. Suction bucket installation: install the soil pressure sensor and negative pore pressure sensor on the suction bucket, use the crane to lift the suction bucket to the center of the model box and control its penetration, and realize the negative pressure penetration of the suction bucket through the negative pressure adjustment system;

[0057] S4, pulling up the suction bucket: after a closed system is formed in the suction bucket, the pulling-up speed is controlled until the suction bucket completely leaves the water surface to simulate the pulling-up process of the suction bucket;

[0058] S5. Data processing: Analyze the static penetration test CPT and flat shovel lateral expansion DMT data obtained from the in-situ test, calculate the physical and mechanical parameters of sand and the penetration bearing capacity of the suction bucket foundation, and establish the relationship between the bearing capacity and soil layer parameters.

[0059] Further: Step S1 specifically includes:

[0060] S11, turn on the switch steel sheet of the sand rain device, so that the sand and soil are uniformly dropped into the model box through the hose;

[0061] S12, control the movement path of the hose from the inner circle to the outer circle and back again, so that the sand is evenly distributed;

[0062] S13, when the sand reaches a predetermined height, bury the pore pressure sensor and continue to prepare the sand sample;

[0063] S14, after the sand falling is completed, the switch steel sheet of the sand rain device is closed, and the sand and soil delivery is ended;

[0064] S15. When the sand is close to the water surface, adjust the water level through the inlet and outlet valves to keep the water level above the sand surface by a certain height;

[0065] Repeat the above steps until the sand fills to the top of the model box.

[0066] Further: Step S5 specifically includes:

[0067] S51, data acquisition: extract cone tip resistance and side wall friction from CPT test, and obtain material index, horizontal stress index and deformation modulus from DMT test;

[0068] S52. Calculate the physical and mechanical parameters of sand: determine the effective vertical stress and internal friction angle of sand based on CPT and DMT data analysis;

[0069] S53. Calculate the penetration resistance of the suction bucket foundation: including the side resistance of the bucket wall and the end resistance of the bucket bottom. The side resistance is calculated by the side pressure coefficient and friction angle of the soil, and the end resistance is determined according to the end resistance per unit area and the bottom area of ​​the suction bucket.

[0070] S54. Calculation of total penetration resistance: Add the resistance of the barrel wall and the resistance of the barrel bottom to obtain the total penetration resistance;

[0071] S55. Establish the relationship between bearing capacity and soil layer parameters: Based on the test data, draw a curve between penetration resistance and soil layer parameters, establish an empirical formula or regression model, and predict the penetration bearing capacity of the suction bucket foundation;

[0072] S56, Model Verification: Compare the calculated penetration resistance with the data measured in the test to verify the accuracy of the model, and adjust the model parameters based on the results to improve the calculation accuracy.

[0073] The present invention has the following beneficial effects:

[0074] The present invention proposes a test device which integrates sample preparation, in-situ testing, suction bucket installation and pulling-up. The design implements a standardized test system and process, provides a reliable and complete means for studying the characteristics of the suction bucket, and provides reliable experimental support for the study of the multiple mechanical properties of the suction bucket foundation, which can promote the application and development of the suction bucket foundation in engineering.

[0075] Compared with the prior art, the advantages of the embodiments of the present invention are at least:

[0076] 1. The present invention integrates the cone penetration test (CPT) and the flat lateral expansion test (DMT) test devices, which can simultaneously obtain important parameters such as the penetration resistance, friction angle and deformation modulus of the soil, providing more comprehensive data support for the bearing capacity evaluation of the suction bucket foundation and the analysis of the mechanical properties of the soil. A calculation method for the bearing capacity and penetration resistance of CPT and DMT can also be established based on the two, which solves the problem of lack of in-situ testing methods in current experiments.

[0077] 2. The modular design of each subsystem (sample preparation system, in-situ test system, installation system) of the present invention facilitates the experimenter to flexibly configure according to different experimental requirements. Each part has strong independence and is easy to disassemble and combine. At the same time, the design of the sand rainer can accurately control the relative density of the sand sample by adjusting the height of the falling sand, and provides a control equation to ensure the consistency of the test under different conditions, further improving the adaptability of the system. It can adapt to various types of suction bucket foundations and marine environmental conditions testing.

[0078] 3. The present invention adopts a digital variable frequency motor, which can realize the study of the influence of different pull-up rates on the pull-out bearing capacity of the suction bucket, and increases the breadth of the research on the engineering characteristics of the suction bucket.

[0079] The test device and method for studying the installation and pull-out of a suction bucket based on static penetration testing of the present invention provide a scientific basis for the design and construction of a suction bucket foundation, and have the advantages of high precision and stability.

[0080] Other beneficial effects of the embodiments of the present invention will be further described below. BRIEF DESCRIPTION OF THE DRAWINGS

[0081] Figure 1 Schematic diagram of a model groove sand filling device according to an embodiment of the present invention.

[0082] Figure 2 Schematic diagram of an in-situ test penetration device according to an embodiment of the present invention.

[0083] Figure 3 It is a schematic diagram of a suction bucket installation device according to an embodiment of the present invention.

[0084] Figure 4 Graph showing the relationship between the sand falling height and relative density of the sand rainer according to an embodiment of the present invention.

[0085] Figure 5 CPT data obtained for the 40% sand sample configured for the embodiment of the present invention.

[0086] Figure 6 DMT data obtained for a 40% sand sample configured for an embodiment of the present invention.

[0087] Figure 7 FIG. 4 is a diagram showing the relationship between displacement and force during the installation process of an embodiment of the present invention.

[0088] In the figure: operating table 1, inlet and outlet valve 2, gravel 3, geotextile 4, sand 5, model box 6, hose 7, sand rain switch 8, sand rain 9, hook 10, crane pulley 11, adjustable crane arm 12, digital frequency conversion motor 13, crane 14, hydraulic pump 15, hydraulic regulating valve 16, hydraulic oil pipe 17, hydraulic jack 18, slotted screw 19, static penetration probe 20, flat shovel side expansion probe 21, DMT penetration hole 22, CPT penetration hole 23, vacuum pump 24, negative pressure regulating valve 25, vacuum cylinder 26, vacuum cylinder double-head water inlet 27, vacuum cylinder water outlet 28, water pumping pipe 29, soil pressure sensor Devices 30-37, pore pressure sensor 38, suction bucket pumping hole 39, suction bucket skirt drainage hole 40, negative pore pressure sensor 41, force sensor 42, wire displacement sensor 43, suction bucket skirt 44, vertical screw 45, wire rope 55, DMT gas-electric pipeline 56, pipeline barometer 57, gas cylinder barometer 58, nitrogen cylinder 59, pressure reducing valve 60, upper ring 61, lower ring 62, jack base 69, CPT data acquisition instrument 70, DMT data acquisition instrument 71, data cable 72, pore pressure sensor bracket 73, sensor mounting device 74, hard plastic pipe 76, and suction bucket top slot 77. DETAILED DESCRIPTION

[0089] The following is a detailed description of the embodiments of the present invention. It should be emphasized that the following description is only exemplary and is not intended to limit the scope and application of the present invention.

[0090] It should be noted that when an element is referred to as being "fixed to" or "disposed on" another element, it can be directly on the other element or indirectly on the other element. When an element is referred to as being "connected to" another element, it can be directly connected to the other element or indirectly connected to the other element. In addition, connection can be used for fixing as well as for coupling or communication.

[0091] It should be understood that the orientation or position relationship indicated by terms such as "length", "width", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside" and "outside" are based on the orientation or position relationship shown in the accompanying drawings, and are only for the convenience of describing the embodiments of the present invention and simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention.

[0092] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the features. In the description of the embodiments of the present invention, the meaning of "plurality" is two or more, unless otherwise clearly and specifically defined.

[0093] See also Figures 1 to 3 The embodiment of the present invention provides a test device for studying the installation and pulling of a suction bucket based on static penetration, including: a model box 6, a sample preparation system, an in-situ test system and a suction bucket installation test system.

[0094] The model box 6 is used to simulate marine environmental conditions, and contains the sand and soil 5 obtained by sample preparation to provide a simulated environment for the suction bucket foundation.

[0095] The sample preparation system is used to prepare sand samples with different relative densities, and the sample preparation system includes: a crane 14, which is used to control the height and sand falling process of the sand rainer 9 to achieve uniform falling of sand; and a sand rainer 9, which is used to control the falling of sand to achieve the preparation of sand samples with expected relative density.

[0096] The in-situ testing system is used to obtain the in-situ mechanical parameters of the soil, and the in-situ testing system includes: a static sounding penetration device (including a static sounding probe 20), which is used to measure the penetration resistance of the soil; a flat shovel side expansion penetration device (including a flat shovel side expansion probe 21), which is used to measure the lateral pressure and deformation modulus of the soil; and a hydraulic device, which is used to drive the penetration device to achieve the penetration and recovery of the probe.

[0097] The suction bucket installation test system is used to simulate the negative pressure penetration process of the suction bucket foundation. The suction bucket installation test system includes: a suction bucket model system, which is used to simulate the installation and pulling-up process of the actual suction bucket; and a negative pressure adjustment system, which is used to control the negative pressure penetration process and simulate the negative pressure environment during the suction bucket sinking and pulling-up by adjusting the negative pressure value.

[0098] See also Figures 1 to 3 The embodiment of the present invention also provides a method for performing a suction bucket installation pull-up test using the test device, comprising the following steps:

[0099] Step S1, preparing sand samples: laying a permeable layer in the model box 6 and injecting water to saturate the sand 5, controlling the height and path of the falling sand by the sand rain device 9 to prepare sand samples with different relative densities, and pre-embedding the pore pressure sensor 38 in the sand 5 obtained by the sample preparation;

[0100] Step S2, in-situ testing: driving the static penetration probe 20 and the flat shovel side expansion probe 21 into the sand 5 through the hydraulic system, continuously collecting static penetration CPT data and flat shovel side expansion DMT data at a set depth to obtain the in-situ mechanical parameters of the soil;

[0101] Step S3, suction bucket installation: install the soil pressure sensors 30-37 and the negative pore pressure sensor 41 on the suction bucket, use the crane 14 to lift the suction bucket to the center of the model box 6 and control its penetration, and realize the negative pressure penetration of the suction bucket through the negative pressure regulating system;

[0102] Step S4, pulling up the suction bucket: after a closed system is formed in the suction bucket, the pulling-up speed is controlled until the suction bucket completely leaves the water surface, so as to simulate the pulling-up process of the suction bucket;

[0103] Step S5, data processing: Analyze the static penetration test CPT and flat shovel lateral expansion DMT data obtained from the in-situ test, calculate the physical and mechanical parameters of the sand and the penetration bearing capacity of the suction bucket foundation, and establish the relationship between the bearing capacity and the soil layer parameters.

[0104] The test device of the present invention is an innovative multifunctional test device that integrates the entire process of sample preparation, in-situ testing, suction bucket installation and pulling, which significantly improves the systematicness of the test and the integrity of the data. By simultaneously introducing the test methods of static penetration testing (CPT) and flat shovel lateral expansion (DMT), the present invention can comprehensively obtain the mechanical parameters of the soil, including penetration resistance, friction angle and deformation modulus, etc., providing more reliable data support for the bearing capacity assessment of the suction bucket foundation. This integrated design solves the problem of lack of uniformity and standardization in traditional tests, so that the comparability and repeatability of the test results are improved. In addition, the control system of the digital variable frequency motor is used to make the adjustment of the suction bucket penetration and pulling rate more precise, and can be flexibly adjusted according to different experimental stages and environmental conditions, optimize experimental efficiency, reduce energy consumption, and reduce disturbances to the surrounding environment, thereby improving the overall accuracy of the experiment. The test device can not only simulate the actual working conditions of the suction bucket foundation in the marine environment, but also adapt to various types of suction bucket foundations, filling the gap in the existing technology of the lack of an in-situ comprehensive suction bucket foundation test system. It is widely used in offshore wind power, offshore oil and gas platforms and other fields, providing a scientific basis and experimental support for the design and construction of related projects, and promoting the application and development of suction bucket foundations in marine structural engineering.

[0105] The specific embodiments of the present invention are further described below.

[0106] A test device and method for studying the installation process of a suction bucket. The device includes a model box, a sample preparation system, an in-situ test system and a suction bucket installation test system. The sample preparation system controls the sand falling process of sand and soil through a crane and a sand rainer to prepare sand samples with different relative densities; the in-situ test system integrates a static penetration test and a flat shovel side expansion penetration device to obtain the in-situ mechanical parameters of the soil; the suction bucket installation test system includes a suction bucket model, a negative pressure regulation system and a vacuum pump to simulate the negative pressure penetration process of the suction bucket foundation. In the data processing process, the cone tip resistance and side wall friction resistance are obtained through CPT, and the material index and horizontal stress index are obtained through DMT. These data are used to establish a data processing method based on the combination of CPT-DMT, and then the penetration resistance of the suction bucket foundation is estimated. The device and method provide a scientific basis for the design and construction of the suction bucket foundation, and have the advantages of high precision and stability.

[0107] A test device for studying a suction bucket installation process based on an in-situ test method comprises a model box, a sample preparation system, an in-situ test system and a suction bucket installation test system.

[0108] Gravel 3 and geotextile 4 are laid in the model box 6 from bottom to top to form a permeable layer. The inlet and outlet valve 2 is located at the bottom of the model box 6, which is used to inject water from the bottom to saturate the sand and soil so that the water level is higher than the geotextile position. The pore pressure sensor 38 is pre-buried in the sand 5 to measure the change of soil pressure. The pore pressure sensor 38 is fixed by the pore pressure sensor bracket 73.

[0109] like Figure 1The sample preparation system is shown, and the sample preparation system includes a crane 14 and a sand rain device 9. The crane 14 is placed on the operating table 1 and welded to the operating table 1 to form a whole. A digital variable frequency motor 13 is installed on the top of the crane 14, and a steel wire rope 55 is wound around the drum of the digital variable frequency motor 13. The steel wire rope 55 is placed on the adjustable crane arm 12 through a pulley 11, and a hook 10 is provided at the tail. The sand rain device 9 controls the height through the crane 14, and sand is dropped to achieve the expected relative density. The digital variable frequency motor 13 is equipped with a reduction box and a frequency converter, which can control the speed of the crane up and down. The upper part of the sand rain device 9 is cylindrical, with a height of 500mm and a diameter of 300mm; the lower part is a conical funnel, with a funnel height of 100mm and a cone angle of 60°. The tail of the funnel is connected to a round tube with a length of 100mm, and a hose 7 with a length of 10mm is provided at the tail end of the round tube. A 5mm thick slit is opened at 40mm from the bottom of the round tube, and a 5mm thick steel sheet is placed at the slit. The length and thickness of the steel sheet are both greater than the diameter of the round tube. The steel sheet is used as the switch steel sheet 8 of the sand rain device. When the steel sheet is pulled out, the sand and soil of the sand rain device falls. When it needs to be closed, the steel sheet is inserted. The sand rain device 9 is controlled by the crane 14 to achieve the expected relative density of sand. The specific control formula is D r =26.9·ln(0.25H). Figure 4 As shown, Dr is the relative density, H is the height of the sand rain gauge from the sand surface in meters.

[0110] like Figure 2 The figure shows a schematic diagram of the in-situ test penetration device. The in-situ test system includes a static penetration device, a flat shovel side expansion penetration device and a hydraulic device. The static penetration device includes a static penetration probe 20 and a slotted screw 19. The static penetration probe 20 is connected to the slotted screw 19 and is inserted into the static penetration hole 23 of the beam frame. The slotted screw 19 has a groove on its shaft, and a wrench can be placed in the groove. The flat shovel side expansion device includes a flat shovel probe 21, a nitrogen bottle 59, a pressure reducing valve 60, and a DMT gas-electric pipeline 56. The flat shovel probe 21 is connected to the slotted screw 19 and is externally connected to the nitrogen bottle 59 through the DMT gas-electric pipeline 56. A pressure reducing valve is provided between the two to calibrate the nitrogen introduced. The hydraulic device includes a hydraulic pump 15, a hydraulic regulating valve 16, a hydraulic oil pipe 17, and a hydraulic jack 18. The liquid pump 15 is placed on the operating table 1, and is connected to the hydraulic jack 18 through the hydraulic oil pipe 17. The hydraulic regulating valve 16 can control the opening and reflux of the hydraulic pump 15. The hydraulic pump 15 drives the jack 18 through oil pressure to realize the lifting and lowering of the crossbeam, thereby driving the penetration and recovery of the static penetration device and the flat shovel side expansion penetration device.

[0111] like Figure 3 Shown is a schematic diagram of a suction bucket installation device, wherein the suction bucket installation test system includes a suction bucket model system and a negative pressure device system.

[0112] The suction bucket model system includes a suction bucket foundation, a soil pressure sensor and a bucket wall sensor installation device 74. The suction bucket foundation is divided into a suction bucket with a skirt and a suction bucket without a skirt, wherein the suction bucket without a skirt is a special case of the suction bucket with a skirt. The suction bucket without a skirt is made of steel with a bottom and a cover, while the suction bucket with a skirt has a skirt added to the outer circle of the bucket wall. Three holes are opened on the cover plate surface of the suction bucket foundation at a distance of 5mm-10mm from the center, and the hole size is 5mm-10mm. More specifically, a suction bucket with a skirt and a height of 240mm is selected as an example. Three holes are opened on the cover plate surface of the suction bucket foundation at a distance of 5mm from the center circle, and the size is 5mm. Two of the holes are symmetrically arranged as suction bucket pumping holes 39 for connecting the pumping pipe 29, and the remaining holes are used to connect the negative pore pressure sensor 41. The barrel-type foundation with skirt has a suction barrel skirt drainage hole 40 at the center of the skirt 44, which is used to drain water during installation of the skirt barrel-type foundation and reduce penetration resistance. The distance and size of the suction barrel water pumping hole 39 from the center are determined according to the size of the barrel-type foundation and the penetration speed. The center of the cover plate surface of the suction barrel foundation is connected to the vertical screw 45 through tapping, and the top of the vertical screw 45 has a hook connected to the lower part of the force sensor 42. The force sensor 42 has rings on the top and bottom, the lower ring 62 is connected to the vertical screw 45, and the upper ring 61 is connected to the hook of the crane.

[0113] The negative pressure regulating system includes a vacuum pump 24 and a solid-liquid separation device. The solid-liquid separation device includes a vacuum cylinder 26, a double-headed water inlet 27 of the vacuum cylinder, a water outlet 28 of the vacuum cylinder, and a negative pressure regulating valve 25. The vacuum cylinder 26 is used to store the water, gas and sand sucked out from the suction bucket during the negative pressure extraction process. The upper part of the vacuum cylinder 26 is equipped with a double-headed water inlet 27 and a true negative pressure regulating valve 25. The negative pressure regulating valve 25 is connected to the vacuum pump 24 to control the negative pressure value extracted by the vacuum pump. A water outlet 28 is installed at the bottom of the vacuum cylinder 26, and the vacuum cylinder water outlet 28 is used to discharge the solid-liquid mixture filled in the vacuum cylinder. The vacuum cylinder 26 is connected to the suction hole 39 of the suction bucket of the barrel-shaped foundation through a water extraction pipe 29.

[0114] This embodiment provides a method for studying the installation process of a suction bucket based on an in-situ test method, the method comprising the following steps:

[0115] (1) Preparation of sand sample: Figure 1As shown, firstly, gravel 3 and geotextile 4 are laid in the model box 6 from bottom to top to form a permeable layer (the thickness of the permeable layer should be less than or equal to 10 cm). Then, the inlet and outlet valve 2 is opened, and water is injected from the bottom to make the water level 10 cm higher than the position of the geotextile 4 to saturate the sand. The height of the sand rainer from the sand surface is confirmed by the relative density control formula and the required relative density. If the relative density is 40%, the height is determined to be 15 mm. When the sand is initially dropped, the height of the sand should be calculated according to the distance between the bottom of the hose 7 and the geotextile 4. Sand is loaded into the sand rainer 9, and then the sand rainer switch steel sheet 8 is opened. When the sand 5 falls, the movement path of the hose 7 needs to be controlled slowly and uniformly. The movement path should be from the inner circle to the outer circle, and then from the outer circle to the inner circle, and the hose 7 moves at a uniform speed throughout the whole process. When the sand reaches the predetermined height, the pre-buried pore pressure sensor 38 is pre-buried using the bracket 73, and then the sand sample is continued. After the sand is dropped, the sand rainer switch steel sheet 8 is closed. When the sand 5 is close to the water surface, continue to let in water from the bottom inlet and outlet valve 2 until it is 10 cm above the sand surface. Repeat the above steps until the liquid level is close to the height of the top of the model box 6.

[0116] (2) In-situ testing: Figure 2 As shown, after the sand sample is prepared, the hydraulic jack 18 is installed on the top of the model box 6 together with the base 69, and then the hydraulic pump 15 is connected to the jack 18 through the hydraulic oil pipe to form a complete hydraulic passage. After that, the slotted screw 19 is connected to the CPT probe 20 and the DMT probe 21 respectively, and the CPT penetration hole 23 and the DMT penetration hole 22 of the pre-opening of the hydraulic jack are passed through the jack and fixed on the jack with a wrench. After that, the two probe data lines 72 are respectively connected to their respective data acquisition instruments, namely the CPT data acquisition instrument 70 and the DMT data acquisition instrument 71. At the same time, the DMT probe 21 is connected to the pressure reducing valve 60 through the gas-electric pipeline 56, so as to be connected to the nitrogen bottle 59 to form a complete closed nitrogen passage. After checking the air tightness, the hydraulic pump 15 can be started, and the hydraulic regulating valve 16 can be used to adjust the direction and speed of the hydraulic jack 18 to perform in-situ testing on the sand 5. During the test, the penetration depth can be controlled by two data acquisition devices 70 and 71. The CPT probe 20 continuously acquires data, and the maximum penetration depth reached is 70 cm; the DMT probe 21 acquires data at 30 cm, 50 cm and 70 cm respectively, thereby obtaining raw data. Figure 5 As shown, when the relative density of sand is 40%, the CPT data obtained include the cone tip resistance q c , pore pressure u 2 and the sidewall friction f s . Figure 6 Shown are the pressure and horizontal stress index K obtained by DMT D .

[0117] (3) Suction bucket installation: Figure 3 As shown, first, connect the soil pressure sensors 30-37 to the sensor mounting device 74 and fix them on the side wall of the suction barrel, and at the same time install the negative pore pressure sensor 41 on the top slot 77 of the suction barrel. The suction barrel used is 240mm high and 100mm in radius. Then, hang the vertical screw 45 of the suction barrel on the lower ring 62, connect the upper ring 61 to the hook of the crane 14, and connect the force sensor 42 to the upper and lower rings 61 and 62 to form a force measurement system. Connect the two ends of the water pumping pipe 29 to the suction barrel water pumping hole 39 and the double-headed water inlet 27 of the vacuum cylinder respectively, and finally connect to the vacuum cylinder 26; connect the vacuum pump 24 to the negative pressure regulating valve 25 through the hard plastic pipe 76, and finally connect to the vacuum cylinder 26 to form a closed vacuum water pumping passage. Fix one end of the wire displacement sensor 43 to the crane 14, and the other end to the suction barrel to form a vertical displacement measurement system. After that, the suction bucket is hoisted to the center of the model box 6 by the crane 14, and the lowering speed of the steel wire rope 55 is controlled by the digital variable frequency motor 13 to achieve the slow self-weight penetration of the suction bucket. Until the suction bucket is completely landed, the connection between the lower ring 62 and the vertical screw 45 of the suction bucket is disconnected, and the suction barrel reaches the maximum depth of self-weight penetration, the vacuum pump 24 is started, and the vacuum negative pressure is controlled by the negative pressure regulating valve 25, and the loading is carried out in stages to achieve the negative pressure penetration of the suction bucket, and finally the suction pipe 29 is sucked in sand and soil and blocked as a sign to stop the installation.

[0118] (4) Pulling up the suction barrel: First, close the suction barrel water extraction hole 39 and the suction barrel skirt drainage hole 40 to form a closed system inside the suction barrel. Reconnect the vertical screw 45, force sensor 42 and crane 14, and connect the pull wire sensor 43 to the top of the suction barrel to form a suction barrel pulling up system. Start the digital variable frequency motor 13 and adjust the tightening speed of the wire rope 55 to achieve speed control of pulling up the suction barrel. Different pulling up speeds can be controlled. Pull up until the suction barrel leaves the water surface as a whole, and the test is over. The data obtained for the installation and pulling up of the suction barrel are as follows: Figure 7 shown.

[0119] (5) Data processing: After the test is completed, the CPT and DMT data obtained in the in-situ test step are used to calculate the physical and mechanical parameters of the sand, and then the penetration bearing capacity of the suction bucket foundation is calculated to establish the relationship between the bearing capacity and the soil layer parameters.

[0120] The specific steps of data processing are as follows:

[0121] (5.1) Data acquisition

[0122] Obtaining the cone tip resistance q from the CPT test c and side wall friction f s ; Obtain material index I from DMT test D , horizontal stress index K Dand deformation modulus E D .

[0123] (5.2) Calculation of the physical and mechanical parameters of sand

[0124] Effective vertical stressσ v ′:σ' v =γ'·z;

[0125] Where: γ′ is the effective unit weight of sand, which can be determined by test or empirical value; z is the depth of soil layer. The internal friction angle φ′ is estimated using CPT data: According to the empirical formula, the internal friction angle φ′ is related to the cone tip resistance q c and effective stress σ v The relationship between ′ is:

[0126]

[0127] Where N kt It is an empirical coefficient, usually ranging from 20 to 30.

[0128] Or use DMT data to estimate, according to DMT material index I D and horizontal stress index K D , the internal friction angle φ′ can be determined by the following relationship: φ'=φ ref +a·log(K D );

[0129] where φ ref is the reference internal friction angle, and a is the empirical coefficient.

[0130] (5.3) Calculation of penetration resistance of suction bucket foundation:

[0131] Barrel wall side resistance Rs:

[0132] For homogeneous sand, it can be simplified as: R s =σ' v ·K t ·tanδ·A s ;

[0133] Where: L is the embedding depth of the suction bucket; Kt is the lateral pressure coefficient of the soil during the penetration process, which can be calculated based on the Kt of DMT. D Value estimation: K t =K 0 ·(1+β·I D ), where K 0 is the static earth pressure coefficient, β is the empirical coefficient. δ is the friction angle between the barrel wall and the sand, which can be taken as δ = 0.8φ′ to φ′; A s =πDL is the side area of ​​the barrel wall, and D is the diameter of the suction barrel.

[0134] Barrel bottom resistance R b : R b =q b ·A b

[0135] Where: q b is the end resistance per unit area, usually approximated as the cone tip resistance qc of the CPT; A b =πD 2 / 4 is the bottom area of ​​the suction barrel.

[0136] (5.4) Calculation of total penetration resistance:

[0137] Total penetration resistance R: R = Rs + Rb

[0138] Through the above calculation, the relationship between the penetration resistance R of the suction bucket foundation and the physical and mechanical parameters of sand can be obtained.

[0139] (5.5) Based on the test data, curves are drawn between penetration resistance and depth, CPT cone tip resistance, DMT parameters, etc., and the influence of each parameter on the penetration performance of the suction bucket is analyzed.

[0140] Establish an empirical formula or regression model to predict the penetration bearing capacity of the suction bucket foundation under different soil conditions.

[0141] (5.6) Verification and application:

[0142] The calculated penetration resistance is compared with the force sensor 42 data and the negative pore pressure sensor 41 measured during the test to verify the accuracy of the calculation model. According to the verification results, the model parameters are adjusted to improve the calculation accuracy. The established model is applied to engineering practice to guide the design and construction of the suction bucket foundation.

[0143] Through technological innovation, the present invention successfully integrates the cone penetration test (CPT) and the flat shovel lateral expansion (DMT) test device, and can carry out continuous testing of the suction bucket foundation from sample preparation, in-situ testing, installation to pull-out. The test device implements a standardized test system and process, provides a mature and complete means of studying the characteristics of suction buckets, and significantly improves the accuracy of the test and the breadth of the data. Through modular design, the various subsystems of the device, such as the sample preparation system, in-situ testing system, and installation system, can be flexibly configured to adapt to various types of suction bucket foundations and marine environmental conditions testing, ensuring the consistency of the test under different conditions.

[0144] The present invention has the ability to accurately control the penetration rate and the pull-out rate of the suction cylinder. Its flexible control capability not only optimizes the experimental efficiency, but also makes the penetration and pull-out process of the suction cylinder smoother, reduces the disturbance to the surrounding environment, and improves the overall accuracy of the experiment.

[0145] The present invention can comprehensively obtain important parameters such as soil penetration resistance, friction angle and deformation modulus, providing more comprehensive data support for the bearing capacity assessment of suction bucket foundations. The ability to accurately control the penetration and pull-out rates enables the present invention to flexibly adjust the rates and optimize construction efficiency according to the requirements of different construction stages and environmental conditions.

[0146] The present invention fills the gap in the prior art of the lack of an in-situ comprehensive suction bucket foundation test system, and is suitable for a wide range of application scenarios such as offshore wind farm foundation design and evaluation, offshore oil and gas platform foundation research, offshore engineering construction verification, and other marine structure foundation research. The test device can not only simulate the sinking and pulling-up process of the suction bucket foundation in the wind farm and optimize the foundation design, but also evaluate the force performance of the suction bucket foundation in a complex seabed environment, support platform foundation design, and ensure construction safety and stability. Therefore, the present invention has important practical significance and broad application prospects for the construction and research of marine structural engineering such as offshore wind power and offshore oil and gas platforms.

[0147] The above content is a further detailed description of the present invention in combination with specific / preferred embodiments, and it cannot be determined that the specific implementation of the present invention is limited to these descriptions. For ordinary technicians in the technical field to which the present invention belongs, without departing from the concept of the present invention, it can also make several substitutions or modifications to these described embodiments, and these substitutions or modifications should be regarded as belonging to the protection scope of the present invention. In the description of this specification, the description of the reference terms "an embodiment", "some embodiments", "preferred embodiments", "examples", "specific examples", or "some examples" means that the specific features, structures, materials or characteristics described in combination with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representation of the above terms does not necessarily target the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner. In the absence of mutual contradiction, those skilled in the art can combine and combine the different embodiments or examples described in this specification and the features of different embodiments or examples. Although the embodiments of the present invention and their advantages have been described in detail, it should be understood that various changes, substitutions and modifications can be made herein without departing from the scope of protection of the patent application.

Claims

1. A test device for studying the installation and pulling of a suction bucket based on static penetration, characterized in that: include: A model box, used for simulating marine environmental conditions, containing sand and soil obtained by sample preparation to provide a simulated environment for the suction bucket foundation; A sample preparation system, used for preparing sand samples of different relative densities, comprising: The crane is used to control the height of the sand rainer and the sand falling process to achieve uniform sand falling; Sand rain device, used to control the falling of sand and soil to achieve the preparation of sand samples with expected relative density; An in-situ testing system is used to obtain in-situ mechanical parameters of soil, and the in-situ testing system comprises: Static cone penetration device, used to measure the penetration resistance of soil; Flat shovel lateral expansion penetration device, used to measure the lateral pressure and deformation modulus of soil; A hydraulic device is used to drive the penetration device to achieve the penetration and recovery of the probe; The suction bucket installation test system is used to simulate the negative pressure penetration process of the suction bucket foundation. The suction bucket installation test system includes: Suction bucket model system, used to simulate the installation and pull-up process of the actual suction bucket; The negative pressure regulating system is used to control the negative pressure penetration process and simulate the negative pressure environment when the suction bucket is sinking and pulling out by adjusting the negative pressure value.

2. The test device for studying the installation and pulling of suction buckets based on static penetration testing as claimed in claim 1 is characterized in that: The model box is provided with: The permeable layer is formed by laying gravel and geotextile in sequence; The inlet and outlet valves are located at the bottom of the model box and are used to inject water from the bottom to saturate the sand and make the water level higher than the geotextile position; Pore ​​pressure sensor, pre-buried in sand, used to measure the change of soil pressure; Bracket, used to fix the pore pressure sensor and ensure its correct position during sand falling.

3. The test device for studying the installation and pulling-up of a suction bucket based on static penetration testing as claimed in claim 1 or 2, characterized in that: The sample preparation system comprises: The crane is installed on the operating table and is equipped with a digital frequency conversion motor on the top. The motor is connected to the pulley system through a wire rope to control the height of the sand rainer and the sand falling process; A sand rain device, which includes a cylindrical upper part and a conical funnel lower part, is used to control and adjust the sand falling height to achieve the expected relative density of sand and soil; The switch is used to control the release and stop of sand in the sand rainer to achieve precise sand falling control.

4. The test device for studying the installation and pulling-up of a suction bucket based on static penetration testing as claimed in claim 3 is characterized in that: The sand rain device comprises: A round pipe, connected to the tail of the funnel, is used to guide the flow of sand; A flexible hose is arranged at the end of the round tube to facilitate the flexible output of sand and soil; The bottom of the circular tube is provided with a slit for controlling the release of sand and soil; The switch comprises a switch steel sheet which is arranged at the cut and can be pulled out or inserted to control the flow of sand and soil.

5. The test device for studying the installation and pulling-up of a suction bucket based on static penetration testing according to any one of claims 1 to 4, characterized in that: The in-situ testing system comprises: A static penetration device, comprising a static penetration probe and a slotted screw, wherein the probe is connected to the screw and is placed in a penetration hole of a beam frame, and is used for static penetration testing of soil; A flat shovel lateral expansion penetration device includes a flat shovel probe, a nitrogen bottle, a pressure reducing valve and a gas-electric pipeline. The probe is connected to a slotted screw and is externally connected to a nitrogen bottle and a pressure reducing valve through a gas-electric pipeline to perform a lateral expansion test on a soil body. The hydraulic device comprises a hydraulic pump, a hydraulic regulating valve, a hydraulic oil pipe and a hydraulic jack. The hydraulic pump is connected to the jack through an oil pipe and is controlled by a regulating valve to drive the penetration and recovery of the penetration device.

6. The test device for studying the installation and pulling-up of a suction bucket based on static penetration testing according to any one of claims 1 to 5, characterized in that: The suction bucket model system comprises: The suction bucket foundation adopts a skirted or non-skirted design. The non-skirted suction bucket is made of steel with a bottom and a cover, and the skirted suction bucket has a skirt structure added to the outer ring of the bucket wall; Soil pressure sensor, installed on the side wall of the suction bucket, used to measure soil pressure; The water pumping holes are symmetrically arranged on the surface of the suction bucket base cover plate and are used to connect the water pumping pipe to realize the water pumping function in the bucket; Negative pore pressure sensor, installed on the surface of the suction bucket base cover, is used to measure the negative pressure in the bucket; The skirt drainage hole is set at the center of the skirt of the skirt barrel foundation to drain water during installation and reduce penetration resistance; A vertical screw connects the suction bucket base cover plate and the force sensor to transmit the force of the suction bucket; The force sensor is connected to the vertical screw and the crane to measure the penetration and pull-out force of the suction bucket.

7. The test device for studying the installation and pulling-up of a suction bucket based on static penetration test according to any one of claims 1 to 6, characterized in that: The negative pressure regulating system comprises: Vacuum pump, used to generate and regulate negative pressure; A solid-liquid separation device, used in conjunction with a vacuum pump, comprises a vacuum cylinder, a double-head water inlet, a water outlet and a negative pressure regulating valve; Vacuum cylinder, used to store water, air and sand sucked from the suction bucket; The double-head water inlet is located on the upper part of the vacuum cylinder and is used in conjunction with the negative pressure regulating valve to control the negative pressure value; A water outlet is provided at the bottom of the vacuum cylinder and is used to discharge the solid-liquid mixture in the vacuum cylinder; The water extraction pipe connects the vacuum cylinder and the water extraction hole of the suction bucket to realize the negative pressure extraction process.

8. A method for performing a suction bucket installation pull-up test using the test device as claimed in any one of claims 1 to 7, characterized in that: The following steps are involved: S1. Prepare sand samples: lay a permeable layer in the model box and inject water to saturate the sand soil. Control the height and path of the falling sand through a sand rain device to prepare sand samples with different relative densities, and pre-embed pore pressure sensors in the sand soil obtained by sample preparation; S2. In-situ testing: The hydraulic system drives the probe into the sand and soil to continuously collect static penetration test (CPT) data and flat shovel side expansion (DMT) data at a set depth to obtain the in-situ mechanical parameters of the soil. S3. Suction bucket installation: install the soil pressure sensor and negative pore pressure sensor on the suction bucket, use the crane to lift the suction bucket to the center of the model box and control its penetration, and realize the negative pressure penetration of the suction bucket through the negative pressure adjustment system; S4, Suction bucket pull-up: After a closed system is formed in the suction bucket, control the pull-up speed. Until the suction bucket completely leaves the water surface to simulate the pulling-up process of the suction bucket; S5. Data processing: Analyze the static penetration test CPT and flat shovel lateral expansion DMT data obtained from the in-situ test, calculate the physical and mechanical parameters of the sand and the penetration bearing capacity of the suction bucket foundation, Establish the relationship between bearing capacity and soil parameters.

9. The method for performing a suction bucket installation pull-up test using the test device as claimed in claim 8, characterized in that: Step S1 specifically includes: S11, turn on the switch steel sheet of the sand rain device, so that the sand and soil are uniformly dropped into the model box through the hose; S12, control the movement path of the hose from the inner circle to the outer circle and back again, so that the sand is evenly distributed; S13, when the sand reaches a predetermined height, bury the pore pressure sensor and continue to prepare the sand sample; S14, after the sand falling is completed, the switch steel sheet of the sand rain device is closed, and the sand and soil delivery is ended; S15. When the sand is close to the water surface, adjust the water level through the inlet and outlet valves to keep the water level above the sand surface by a certain height; Repeat the above steps until the sand fills to the top of the model box.

10. The method for performing a suction bucket installation pull-up test using the test device as claimed in claim 8 or 9, characterized in that: Step S5 specifically includes: S51, data acquisition: extract cone tip resistance and side wall friction from CPT test, and obtain material index, horizontal stress index and deformation modulus from DMT test; S52. Calculate the physical and mechanical parameters of sand: determine the effective vertical stress and internal friction angle of sand based on CPT and DMT data analysis; S53. Calculate the penetration resistance of the suction bucket foundation: including the side resistance of the bucket wall and the end resistance of the bucket bottom. The side resistance is calculated by the side pressure coefficient and friction angle of the soil, and the end resistance is determined according to the end resistance per unit area and the bottom area of ​​the suction bucket. S54. Calculation of total penetration resistance: Add the resistance of the barrel wall and the resistance of the barrel bottom to obtain the total penetration resistance; S55. Establish the relationship between bearing capacity and soil layer parameters: Based on the test data, draw a curve between penetration resistance and soil layer parameters, establish an empirical formula or regression model, and predict the penetration bearing capacity of the suction bucket foundation; S56, Model Verification: Compare the calculated penetration resistance with the data measured in the test to verify the accuracy of the model, and adjust the model parameters based on the results to improve the calculation accuracy.

Images