An apparatus and method for studying acoustic emission phenomena during hard shell formation penetration

Abstract

This application discloses an apparatus for studying acoustic emission phenomena during the puncture process in hard-shell strata, comprising a hydraulic cylinder connected to a hydraulic control system; a pile rod with displacement and tension / compression sensors connected thereto; a pile shoe model; a water bladder system with a water bladder pressure sensor; a housing containing soil and hard-shell strata to simulate a marine geological environment, with acoustic emission signal sensors embedded in the soil layer; a signal acquisition system; and a central control system for controlling the movement of the hydraulic cylinder based on signals to move the pile shoe model up and down to simulate offshore platform pile driving experiments, simultaneously acquiring acoustic emission signals, and determining the acoustic emission signal characteristics during the hard-shell strata puncture process to assist in puncture prediction during offshore platform pile driving operations. This apparatus can study acoustic emission phenomena during puncture under non-centrifuge conditions on land, providing support for pile shoe puncture prediction based on acoustic emission phenomena. This application also discloses a method for studying acoustic emission phenomena during the puncture process in hard-shell strata, which has the same advantages.

Description

Technical Field

[0001] This invention belongs to the field of offshore oil drilling technology, and in particular relates to a device and method for studying acoustic emission phenomena during the puncture process of hard-shell formations. Background Technology

[0002] Offshore oil and gas is a crucial pillar of energy security. As a core piece of equipment for near-shore development, the safety of pile driving operations on jack-up drilling platforms directly impacts operational efficiency and personnel safety. In widely distributed "hard on top, soft on the bottom" geological formations, the pile legs are prone to uncontrollable "puncture" disasters, causing significant economic losses or even platform capsizing. Therefore, predicting puncture accidents before the pile shoes puncture the hard shell and ensuring the safety of pile driving operations on jack-up drilling platforms is of paramount importance.

[0003] The puncture of the ground at the bottom of the pile shoe during pile driving is accompanied by the generation of multiple physical fields, including mechanical and acoustic fields. As the pile shoe sinks under the load, the formation and development of the puncture state in the hard-shell strata at the bottom of the pile shoe is actually a deformation and fatigue fracture process of the strata under the simultaneous increase of normal and shear stresses. The fatigue deformation and fracture process of the strata is inevitably accompanied by the generation of acoustic emission (AE) signals. Therefore, AE signal parameters during the puncture process, such as effective events, energy, similarity, and amplitude-frequency relationship, can predict the occurrence of puncture accidents. Simulating the puncture phenomenon on the ground and studying the characteristics of the acoustic emission signals during this process can provide a scientific basis for using acoustic emission phenomena to solve the puncture prediction problem in the pile driving operation of offshore drilling platforms. However, there is currently no device or method to study the acoustic emission phenomenon during the puncture process in hard-shell strata. Summary of the Invention

[0004] To address the aforementioned issues, this invention provides a device and method for studying acoustic emission phenomena during the puncture process in hard-shell formations. This device can simulate the puncture phenomenon on the ground under non-centrifuge conditions and record acoustic emission signals in real time during the puncture process, thereby studying the acoustic emission phenomenon during puncture and providing support for pile shoe puncture prediction based on acoustic emission phenomena.

[0005] The present invention provides a device for studying acoustic emission phenomena during the puncture process of hard crustal strata, comprising:

[0006] The hydraulic cylinder is connected to the hydraulic control system.

[0007] A pile rod is installed below the hydraulic cylinder, and a displacement sensor and a tension / compression sensor are connected to it;

[0008] A pile shoe model is installed at the lower end of the pile rod;

[0009] A water bladder system, used to simulate the overburden pressure of the formation, has a through hole in the middle to accommodate the pile rod, and includes a water bladder pressure sensor;

[0010] The enclosure contains soil and hard crust layers to simulate a marine geological environment. The soil layers have built-in acoustic emission signal sensors, and the water bladder system is installed on the upper part of the soil layers.

[0011] The signal acquisition system is communicatively connected to the displacement sensor, the tension / compression sensor, the water bladder pressure sensor, and the acoustic emission signal sensor, and is used to acquire displacement signals, thrust signals, and water bladder pressure signals.

[0012] The central control system is communicatively connected to the hydraulic control system and the signal acquisition system. It is used to control the movement of the hydraulic cylinder through the hydraulic control system based on the displacement signal and the thrust signal to realize the up and down movement of the pile shoe model to simulate the offshore platform pile driving experiment. Simultaneously, it acquires acoustic emission signals and determines the acoustic emission signal characteristics during the hard crust stratum puncture process to assist in the puncture prediction during offshore platform pile driving operations.

[0013] Preferably, in the acoustic emission phenomenon research device during the above-mentioned hard crust stratum puncture process, the acoustic emission signal sensor is set at the boundary between the soil layer and the hard crust stratum.

[0014] Preferably, in the acoustic emission phenomenon research device during the above-mentioned hard crust strata puncture process, the water bag system includes a water bag body, a pressure plate, a top cover, and a pressure plate. The pressure plate is screwed onto the housing to fix the top cover, and the distance between the top cover and the pressure plate is adjustable to adjust the overburden pressure of the simulated strata of the water bag body. The pressure plate has a first opening as a water inlet and a second opening for accommodating the water bag pressure sensor. The first opening is connected to a pressure stabilizing tank through a water pipe. The lower part of the pressure stabilizing tank contains water, and the upper part contains compressed air. The pressure of the water bag body is adjusted by adjusting the pressure of the compressed air.

[0015] Preferably, in the acoustic emission phenomenon research equipment during the above-mentioned hard crust strata piercing process, both the upper and lower ends of the tension and compression sensor are threaded, with the upper end connected to the protruding end of the hydraulic cylinder and the lower end connected to the pile rod.

[0016] Preferably, the acoustic emission phenomenon research device in the above-mentioned hard crust stratum piercing process also includes a column set around the pile rod, the upper end of the column is connected to the upper plate by bolts, and the lower end of the column is fixed to the lower box body by screws.

[0017] Preferably, in the above-mentioned acoustic emission phenomenon research equipment during the puncture process of hard crust strata, the displacement sensor is a wire-type displacement sensor, which is fixed below the upper plate, and its wire ring is connected to the connecting plate, which is fixed to the lower end of the tension-compression sensor.

[0018] Preferably, in the acoustic emission phenomenon research device during the above-mentioned hard crust strata piercing process, two pile rod supports are fixed on the column, the two pile rod supports are fastened together near the pile rod, and bullseye universal ball bearings are installed on the pile rod supports to ensure that the pile rod moves in the vertical direction.

[0019] Preferably, in the above-mentioned equipment for studying acoustic emission phenomena during the puncture process of hard crustal strata, the lower end of the hydraulic cylinder is connected to the upper end of the pile rod by bolts through a flange.

[0020] Preferably, in the above-mentioned acoustic emission phenomenon research equipment during the puncture process of hard crustal strata, the hydraulic cylinder is connected to the hydraulic control system through an oil pipe, and the central control system is a host computer.

[0021] This invention provides a method for studying acoustic emission phenomena during the puncture process of hard-crust strata, utilizing the acoustic emission phenomenon study equipment during the puncture process of hard-crust strata as described in any of the above claims, including:

[0022] Permeable stones are placed at the bottom of the box, and geotextile is covered on top of them. The first soft soil layer is placed on the geotextile to simulate a soft soil layer.

[0023] A hard soil layer is laid on top of the first soft soil layer to simulate a hard crust stratum;

[0024] Acoustic emission sensors were arranged on the hard soil layer;

[0025] A second layer of soft soil is laid on top of the hard crust layer to simulate the soft crust deposited on the actual seabed surface.

[0026] Install the pile poles and pile shoe models, and connect the water bladder system;

[0027] The pressure of the water bladder system is brought to a preset value to simulate the overburden pressure of the formation.

[0028] According to the experimental mode, control parameters and control curves are sent to the hydraulic control system. The hydraulic cylinder is controlled to drive the pile shoe model to insert into the first soft soil layer according to the set mode. The displacement signal, thrust signal, water bladder pressure signal and acoustic emission signal of the pile rod are collected in real time. When the pile shoe model penetrates into the second soft soil layer to a preset depth, the experiment is completed. The motion control mode of the pile shoe model is speed mode or thrust mode.

[0029] Based on the acoustic emission signals, the acoustic emission signal characteristics during the puncture process of hard crustal strata are determined to assist in puncture prediction during offshore platform pile driving operations.

[0030] As described above, the acoustic emission phenomenon research device for the piercing process of hard crust strata provided by the present invention includes: a hydraulic cylinder connected to a hydraulic control system; a pile rod located below the hydraulic cylinder, on which a displacement sensor and a tension / compression sensor are connected; a pile shoe model located at the lower end of the pile rod; a water bladder system for simulating the overburden pressure of the strata, having a through hole in the middle to accommodate the pile rod and a water bladder pressure sensor; a housing containing soil layers and hard crust strata to simulate a marine stratum environment, with an acoustic emission signal sensor built into the soil layer and the water bladder system located on top of the soil layer; a signal acquisition system communicatively connected to the displacement sensor, the tension / compression sensor, the water bladder pressure sensor, and the acoustic emission signal sensor, for acquiring displacement signals, thrust signals, and water bladder pressure signals; and a central control system communicatively connected to the hydraulic control system and the signal acquisition system, for acquiring displacement signals, thrust signals, and water bladder pressure signals based on the displacement signals, thrust signals, and water bladder pressure sensors. The force signal controls the movement of the hydraulic cylinder through the hydraulic control system to move the pile shoe model up and down to simulate the pile driving experiment on an offshore platform. Simultaneously, acoustic emission signals are acquired to determine the characteristics of acoustic emission signals during the puncture process in hard-shell strata, assisting in puncture prediction during offshore platform pile driving operations. This device can simulate puncture phenomena on the ground and record acoustic emission signals in real time during the puncture process, thereby studying the acoustic emission phenomenon and providing support for pile shoe puncture prediction based on acoustic emission phenomena. By conducting experiments on simulated marine strata of different specifications, strengths, and ratios of soft and hard strata, the specific conditions of pile driving operations in complex and variable marine geological environments can be obtained. Through analysis and processing of acoustic emission signals during the puncture process, a predictive model for hard-shell strata puncture can be established. When the acoustic emission signal count rate or frequency reaches its peak, it indicates that the bearing capacity will reach its peak, and an early warning can be issued to facilitate the implementation of corresponding emergency measures. The method for studying acoustic emission phenomena during the puncture process in hard-shell strata provided by this invention has the same advantages as the aforementioned device. Attached Figure Description

[0031] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort.

[0032] Figure 1 A schematic diagram of an embodiment of a device for studying acoustic emission phenomena during the puncture process of a hard-shell stratum provided by the present invention;

[0033] Figure 2 A structural diagram of the control system of the equipment used to study acoustic emission phenomena during the piercing process of hard crustal strata;

[0034] Figure 3 This is a schematic diagram of the speed mode control logic;

[0035] Figure 4 This is a schematic diagram of the thrust mode control logic;

[0036] Figure 5 This is a schematic diagram of an embodiment of a method for studying acoustic emission phenomena during the puncture process of a hard-shell stratum provided by the present invention.

[0037] The annotations in the attached figures are explained as follows:

[0038] 1. Hydraulic cylinder; 2. Hydraulic control system; 3. Pile rod; 4. Pile shoe model; 5. Water bladder system; 6. Box body; 7. Signal acquisition system; 8. Central control system; 9. Column; 10. Pile rod support; 11. Bullseye universal ball bearing; 12. Acoustic emission signal sensor support; 13. Anti-tilt base plate; 31. Displacement sensor; 32. Tension and compression sensor; 51. Water bladder pressure sensor; 52. Water bladder body; 53. Pressure plate; 54. Top cover; 55. Pressure plate; 56. Water inlet; 57. Pressure stabilizing tank; 61. Acoustic emission signal sensor. Detailed Implementation

[0039] The core of this invention is to provide a device and method for studying acoustic emission phenomena during the puncture process of hard-shell strata. This device can simulate the puncture phenomenon on the ground and record acoustic emission signals in real time during the puncture process. This allows for the study of acoustic emission phenomena during the puncture process under non-centrifuge conditions on the ground, providing support for pile shoe puncture prediction based on acoustic emission phenomena.

[0040] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0041] In existing technologies, puncture incidents involving the legs of jack-up platforms can cause significant economic losses. Although considerable research has been conducted on the occurrence and prevention of punctures, their occurrence remains difficult to avoid. Therefore, in simulated puncture experiments during offshore platform pile driving operations, it is urgent to construct experimental devices that simulate actual offshore platform pile driving operations and to conduct experimental analyses of various marine geological structures under different conditions, thereby predicting puncture phenomena in actual offshore platform pile driving operations.

[0042] To address the aforementioned problems, this invention provides an apparatus for studying acoustic emission phenomena during the puncture process of hard-crust strata. Examples of its implementation include... Figure 1 As shown, Figure 1 This is a schematic diagram of an embodiment of a device for studying acoustic emission phenomena during the puncture process of a hard-crust strata provided by the present invention. The device may include:

[0043] Hydraulic cylinder 1, connected to hydraulic control system 2, is the power part of the equipment. The extension of hydraulic cylinder 1 can drive the simulated pile shoe to puncture the soil sample.

[0044] The pile rod 3 is located below the hydraulic cylinder 1, and a displacement sensor 31 and a tension / compression sensor 32 are connected to it to collect the thrust and displacement signals during the pile driving operation.

[0045] The pile shoe model 4 is set at the lower end of the pile rod 3. It should be noted that this pile shoe model is a scaled-down model of the actual pile shoe, so that the contact shape between the pile shoe model and the soil sample during the pile driving experiment is consistent with the actual pile driving operation, thereby ensuring the accuracy of the simulation experiment.

[0046] The water bladder system 5 is used to simulate the overburden pressure of the strata. It has a through hole in the middle to accommodate the pile rod 3 and a water bladder pressure sensor 51. The pile shoe model 4 is placed on the lower side of the water bladder system 5.

[0047] The box 6, which may be, but is not limited to, cylindrical, contains soil and hard crust strata to simulate marine geological environments. Six drainage holes are distributed around the bottom of the box for drainage during soil preparation. The legs of the box can be equipped with grid-shaped anti-tilting supports. Furthermore, the soil layer contains an acoustic emission signal sensor 61, which can be mounted on an acoustic emission signal sensor bracket 12 to collect sound wave signals during puncture. A water bladder system 5 is installed on the upper part of the soil layer. This water bladder system 5 and the box 6 work together to simulate the specific marine geological environment. Experimental soil samples are placed in the box according to different specifications and ratios. The water bladder system 5 is used to simulate overburden pressure. The lower part of the box 6 can be supported by an anti-tilting base plate 13, which can improve the stability of the entire device from the bottom.

[0048] The signal acquisition system 7 is communicatively connected to the displacement sensor 31, the tension and compression sensor 32, the water bladder pressure sensor 51, and the acoustic emission signal sensor 61, and is used to acquire displacement signals, thrust signals, and water bladder pressure signals.

[0049] The central control system 8 is connected to the hydraulic control system 2 and the signal acquisition system 7. It is used to control the movement of the hydraulic cylinder 1 through the hydraulic control system 2 based on the displacement signal and thrust signal to realize the up and down movement of the pile shoe model 4 to simulate the offshore platform pile driving experiment. Simultaneously, it acquires the acoustic emission signal and determines the acoustic emission signal characteristics during the hard crust stratum puncture process to assist in the puncture prediction during the offshore platform pile driving operation.

[0050] It should be noted that the aforementioned hydraulic control system 2, signal acquisition system 7, and central control system 8 together constitute an integrated control system, mainly realizing programmed simulated pile shoe motion control and acoustic emission signal acquisition. (Refer to...) Figure 2 , Figure 2 This diagram illustrates the structure of the control system for a device used to study acoustic emission phenomena during the penetration of hard-shell strata. This hydraulic control system consists of a hydraulic tank, hydraulic pump, frequency converter, servo valve, hydraulic gauge, three-position four-way valve, and a hydraulic control microcontroller. The hydraulic tank stores hydraulic oil and also receives hydraulic oil returned from the servo valve. The hydraulic pump generates high-pressure hydraulic oil when started by the frequency converter. This high-pressure hydraulic oil, regulated by the servo valve, drives the hydraulic cylinder, thereby controlling the speed and pressure of the simulated pile shoe inserting into the soil, simulating the actual pile driving process. The three-position four-way valve switches between oil inlet and outlet in the hydraulic cylinder, enabling forward and backward movement. The hydraulic control microcontroller, based on commands from the host computer, the speed and displacement from the displacement sensor, the pressure value from the tension / compression sensor, and the outlet hydraulic pressure value, controls the servo valve to achieve the motion control of the pile rod. The signal acquisition system consists of a multi-channel high-speed, high-precision ADC, an FPGA acquisition controller, and a USB 3.0 interface. The multi-channel high-speed, high-precision ADC acquires the output signals from the wire displacement sensor, tension / compression sensor, water bladder pressure sensor, and acoustic emission signal sensor. The FPGA control controller manages the ADC acquisition and transmits the pile's speed, displacement, and pressure values ​​to the hydraulic control microcontroller via a high-speed 485 bus. The USB 3.0 interface uploads all acquired data to the central control system, which sets the hydraulic control mode and displays all acquired data in real time.

[0051] The stake driving control has two modes: speed mode and thrust mode. The control logic block diagrams for the two modes are as follows: Figure 3 and Figure 4 As shown, Figure 3 This is a schematic diagram of the speed mode control logic. Figure 4This is a schematic diagram of the thrust mode control logic. In speed mode, the central control system sets the speed curve for simulating pile shoe movement. The hydraulic control microcontroller implements a two-layer control: an inner thrust loop and an outer speed loop, both using PID algorithms. The outer speed loop calculates the current thrust value based on the current speed and the speed curve using a PID algorithm. The inner loop outputs the thrust value based on the current thrust and the speed loop, and controls the servo valve driver through a PID algorithm to achieve thrust control, thus simulating pile driving according to a specific speed curve. In thrust mode, the central control system sets the thrust curve and speed constraint value for simulating pile shoe movement. The hydraulic control microcontroller implements a two-layer control: an inner thrust loop using a PID algorithm; and an outer speed constraint loop. When the speed exceeds the speed constraint value, the thrust curve is delayed. The inner loop controls the servo valve driver through a PID algorithm based on the current thrust and speed constraint state to achieve thrust control, thus simulating pile driving according to a specific thrust curve.

[0052] The aforementioned equipment enables the simulation of piercing hard-shell strata during offshore platform piling operations. The experiment can obtain the force, displacement, and acoustic emission signals during the piercing process. By conducting experiments on simulated marine strata of different specifications, strengths, and ratios of soft and hard strata, the specific conditions of piling operations in complex and variable marine geological environments can be obtained. Through the analysis and processing of acoustic emission signals during the piercing process, a predictive model for piercing the hard-shell bottom layer can be established.

[0053] As described above, the embodiment of the acoustic emission phenomenon research device during the puncture process of the hard crust strata provided by the present invention includes: a hydraulic cylinder connected to a hydraulic control system; a pile rod located below the hydraulic cylinder, on which a displacement sensor and a tension / compression sensor are connected; a pile shoe model located at the lower end of the pile rod; a water bladder system for simulating the overburden pressure of the strata, having a through hole in the middle to accommodate the pile rod and a water bladder pressure sensor; a housing containing soil and hard crust strata to simulate a marine stratum environment, with an acoustic emission signal sensor built into the soil layer and a water bladder system installed on top of the soil layer; a signal acquisition system communicatively connected to the displacement sensor, tension / compression sensor, water bladder pressure sensor, and acoustic emission signal sensor, for acquiring displacement signals, thrust signals, and water bladder pressure signals; and a central control system communicatively connected to the hydraulic control system and the signal acquisition system, for controlling the hydraulic system based on the displacement signal and thrust signal. The system controls the movement of hydraulic cylinders to move the pile shoe model up and down to simulate the pile driving experiment on an offshore platform. Simultaneously, it acquires acoustic emission signals to determine the characteristics of acoustic emission signals during the puncture process in hard-shell strata, thus assisting in puncture prediction during offshore platform pile driving operations. This demonstrates that the equipment can simulate puncture phenomena on the ground and record acoustic emission signals in real time during the puncture process, thereby studying the acoustic emission phenomenon and providing support for pile shoe puncture prediction based on acoustic emission phenomena. Through experiments on simulated marine strata of different specifications, strengths, and ratios of soft and hard strata, the specific conditions of pile driving operations in complex and varied marine geological environments can be obtained. By analyzing and processing the acoustic emission signals during the puncture process, a predictive model for puncture of the hard-shell bottom layer can be established. When the acoustic emission signal count rate reaches its peak or the acoustic emission signal frequency reaches its peak, it indicates that the bearing capacity will reach its peak, and an early warning can be issued to facilitate the implementation of corresponding emergency response measures.

[0054] In a specific embodiment of the acoustic emission phenomenon research equipment during the aforementioned hard-shell stratum puncture process, the acoustic emission signal sensor 61 is positioned at the boundary between the soil layer and the hard-shell stratum, enabling more accurate measurement of the acoustic emission signal during puncture. During the experiment, soil samples are mixed in various proportions to simulate the actual "soft-hard-soft" marine geological environment, reducing the cost of the experiment. In this configuration, the interior of the enclosure, from bottom to top, consists of the soil layer, the acoustic emission sensor, the water bladder and its pressure plate, the top cover, and the pressure plate.

[0055] Continue to refer to Figure 1In another specific embodiment of the acoustic emission phenomenon research equipment during the above-mentioned hard crust stratum puncture process, the water bag system 5 may include a water bag body 52, a pressure plate 53, a top cover 54, and a pressure plate 55. The pressure plate 55 is screwed onto the housing 6 to fix the top cover 54, and the distance between the top cover 54 and the pressure plate 55 is adjustable to adjust the overburden pressure of the simulated stratum in the water bag body 52. ​​The pressure plate 53 has a first opening as a water inlet 56 and a second opening for accommodating the water bag pressure sensor 51. This first opening is connected to the pressure stabilizing tank 57 through a water pipe. The lower part of the pressure stabilizing tank 57 is filled with water, and the upper part is filled with compressed air. By adjusting the pressure of the compressed air, a fixed pressure of water is injected into the water bag body 52, thereby adjusting the pressure of the water bag body 52. ​​This pressure stabilizing tank can provide a stable overburden pressure during the pile driving operation. Specifically, the lower one-fifth of the pressure stabilizing tank can be set to water, and the upper four-fifths of the pressure stabilizing tank can be filled with compressed air. Of course, this can be selected according to actual needs. The lower side of the water bladder body is in close contact with the soil layer. By adjusting the long screw passing through the top cover, the specific position of the water bladder body can be changed, enabling the device to conduct experiments under soil layers of different thicknesses. The presence of this water bladder body more accurately simulates the overburden pressure, and together with the real-time signal acquisition of various sensors, the simulation results are more precise. Furthermore, both ends of the tension / compression sensor 32 are preferably threaded, with the upper end connected to the protruding end of the hydraulic cylinder 1 and the lower end connected to the pile rod 3. This ensures a more secure connection, preventing it from easily falling off and guaranteeing the safety of the entire experimental process.

[0056] Continue to refer to Figure 1 In another specific embodiment of the acoustic emission phenomenon research equipment during the above-mentioned hard crust stratum piercing process, the equipment may also include a column 9 set around the pile rod 3. The upper end of the column 9 is connected to the upper plate by bolts, and the lower end of the column 9 is fixed to the lower box 6 by screws. That is to say, a platform is installed on the upper end of the box, which is used to fix the column. These parts constitute the support part of the entire equipment, providing structural support for the overall equipment and ensuring the normal and stable operation of the pile driving operation.

[0057] In a preferred embodiment of the acoustic emission phenomenon research equipment during the aforementioned hard-shell stratum piercing process, the displacement sensor 31 can be a wire-type displacement sensor. The wire-type displacement sensor is fixed below the upper plate, and its wire loop is connected to the connecting plate, which is fixed to the lower end of the tension / compression sensor 32. In this case, when the hydraulic cylinder extends, it will drive the tension / compression sensor 32, the connecting plate, and the pile rod to move downwards simultaneously, thereby causing the wire loop of the wire-type displacement sensor to move downwards. The wire-type displacement sensor can then output the displacement and velocity information of the pile shoe model. Of course, other types of displacement sensors can be selected according to actual needs; this is not a limitation.

[0058] In another preferred embodiment of the acoustic emission phenomenon research device during the above-mentioned hard crust strata piercing process, two pile rod supports 10 are fixed on the column 9. The two pile rod supports 10 are fastened together near the pile rod, and bullseye universal ball bearings 11 are installed on the pile rod supports to ensure that the pile rod moves in the vertical direction, thereby preventing deviation and making the pile insertion operation more standardized.

[0059] In another preferred embodiment of the acoustic emission phenomenon research equipment during the aforementioned hard-shell stratum piercing process, the lower end of the hydraulic cylinder 1 can be connected to the upper end of the pile rod 3 via a flange using bolts, ensuring a more secure connection. Furthermore, this hydraulic cylinder 1 can be connected to the hydraulic control system 2 via an oil pipe, and the central control system 8 can preferably be a host computer.

[0060] An example of the implementation of the method for studying acoustic emission phenomena during the puncture process of hard crustal strata provided by this invention. Figure 5 As shown, Figure 5 This is a schematic diagram of an embodiment of a method for studying acoustic emission phenomena during hard-crust strata piercing provided by the present invention. Using the acoustic emission phenomenon study equipment for hard-crust strata piercing as described above, the method may include the following steps:

[0061] S1: Place the permeable stone at the bottom of the box, cover it with geotextile, and place the first soft soil layer on the geotextile to simulate the soft soil layer.

[0062] S2: Lay a hard soil layer on top of the first soft soil layer to simulate a hard crust stratum;

[0063] S3: Deploy acoustic emission sensors on hard soil layers;

[0064] Specifically, an acoustic emission sensor mounting bracket can be placed on the hard soil layer first, and then the acoustic emission sensor can be fixed on this bracket.

[0065] S4: Continue to lay a second layer of soft soil on top of the hard crust layer to simulate the soft soil layer of actual seabed surface sedimentation.

[0066] S5: Install the pile pole and pile shoe model, and connect the water bladder system;

[0067] Specifically, it involves installing the water bladder body and the water bladder pressure plate.

[0068] S6: To bring the pressure of the water bladder system to a preset value to simulate the overburden pressure of the formation;

[0069] Specifically, the top cover and pressure plate of the box can be installed, the pressure stabilizing tank and the water bladder body can be connected, and compressed air can be injected into the air bladder of the pressure stabilizing tank to make the air bladder pressure reach the rated value. At this time, the pressure of the air bladder and the water bladder body is balanced, thus simulating the pressure of the top cover.

[0070] S7: According to the experimental mode, send control parameters and control curves to the hydraulic control system, control the hydraulic cylinder to drive the pile shoe model to insert into the first soft soil layer according to the set mode, and collect the displacement signal, thrust signal, water bladder pressure signal and acoustic emission signal of the pile rod in real time. When the pile shoe model penetrates into the second soft soil layer to a preset depth, the experiment is completed. The motion control mode of the pile shoe model is speed mode or thrust mode.

[0071] Specifically, the experiment can be completed after penetrating the hard crust strata and entering the second soft soil layer 100mm below.

[0072] S8: Determine the acoustic emission signal characteristics during the puncture process of hard crustal strata based on acoustic emission signals to assist in puncture prediction during offshore platform pile driving operations.

[0073] In subsequent processes, this experimental equipment can be used to mix different geological structures, conduct experiments under different pressures and speeds during pile driving operations, simulate the actual pile driving process of offshore platforms, collect relevant signals, analyze and process various signals, and establish a predictive model for hard-shell bottom penetration.

[0074] The aforementioned equipment and methods can specifically simulate offshore platform pile driving experiments, collect various signals during pile driving operations, and provide support for subsequent puncture prediction during specific offshore platform pile driving operations. They offer advantages such as ease of operation, high efficiency, low cost, and good results. The entire equipment has a simple structure and is easy to operate, effectively achieving the experimental objectives. When placing soil samples, the pile rods and boots can be disassembled and quickly reassembled, avoiding large-scale disassembly and improving work efficiency during experiments.

[0075] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A device for studying acoustic emission phenomena during the puncture process of hard-crust strata, characterized in that, include: The hydraulic cylinder is connected to the hydraulic control system. A pile rod is installed below the hydraulic cylinder, and a displacement sensor and a tension / compression sensor are connected to it; A pile shoe model is installed at the lower end of the pile rod; A water bladder system, used to simulate the overburden pressure of the formation, has a through hole in the middle to accommodate the pile rod, and includes a water bladder pressure sensor; The enclosure contains soil and hard crust layers to simulate a marine geological environment. The soil layers have built-in acoustic emission signal sensors, and the water bladder system is installed on the upper part of the soil layers. The signal acquisition system is communicatively connected to the displacement sensor, the tension / compression sensor, the water bladder pressure sensor, and the acoustic emission signal sensor, and is used to acquire displacement signals, thrust signals, and water bladder pressure signals. The central control system is communicatively connected to the hydraulic control system and the signal acquisition system. It is used to control the movement of the hydraulic cylinder through the hydraulic control system based on the displacement signal and the thrust signal to realize the up and down movement of the pile shoe model to simulate the offshore platform pile driving experiment. Simultaneously, it acquires acoustic emission signals and determines the acoustic emission signal characteristics during the hard crust stratum puncture process to assist in the puncture prediction during offshore platform pile driving operations.

2. The apparatus for studying acoustic emission phenomena during hard crust strata piercing according to claim 1, characterized in that, The acoustic emission signal sensor is located at the boundary between the soil layer and the hard crust stratum.

3. The apparatus for studying acoustic emission phenomena during hard crust strata piercing according to claim 1, characterized in that, The water bladder system includes a water bladder body, a pressure plate, a top cover, and a pressure plate. The pressure plate is screwed onto the housing to fix the top cover, and the distance between the top cover and the pressure plate is adjustable to adjust the overburden pressure of the simulated strata of the water bladder body. The pressure plate has a first opening as a water inlet and a second opening for accommodating the water bladder pressure sensor. The first opening is connected to a pressure stabilizing tank through a water pipe. The lower part of the pressure stabilizing tank contains water, and the upper part contains compressed air. The pressure of the water bladder body is adjusted by adjusting the pressure of the compressed air.

4. The apparatus for studying acoustic emission phenomena during hard crust strata piercing according to claim 1, characterized in that, The tension / compression sensor has threads at both ends; its upper end is connected to the extended end of the hydraulic cylinder, and its lower end is connected to the pile rod.

5. The apparatus for studying acoustic emission phenomena during the puncture process of hard-crust strata according to claim 1, characterized in that, It also includes columns arranged around the pile, the upper end of the columns being bolted to the upper plate, and the lower end of the columns being fixed to the lower box body by screws.

6. The apparatus for studying acoustic emission phenomena during the puncture process of hard-crust strata according to claim 5, characterized in that, The displacement sensor is a wire-type displacement sensor, which is fixed below the upper plate. Its wire loop is connected to the connecting plate, which is fixed to the lower end of the tension / compression sensor.

7. The apparatus for studying acoustic emission phenomena during hard crust strata piercing according to claim 5, characterized in that, Two pile rod supports are fixed on the column. The two pile rod supports are fastened together near the pile rod, and bullseye universal ball bearings are installed on the pile rod supports to ensure that the pile rod moves in the vertical direction.

8. The apparatus for studying acoustic emission phenomena during the puncture process of hard-crust strata according to claim 1, characterized in that, The lower end of the hydraulic cylinder is connected to the upper end of the pile rod via a flange using bolts.

9. The apparatus for studying acoustic emission phenomena during the puncture process of hard-crust strata according to claim 1, characterized in that, The hydraulic cylinder is connected to the hydraulic control system via an oil pipe, and the central control system is a host computer.

10. A method for studying acoustic emission phenomena during the puncture process of hard-crust strata, characterized in that, The apparatus for studying acoustic emission phenomena during the puncture process of hard crustal strata as described in any one of claims 1-9 includes: Permeable stones are placed at the bottom of the box, and geotextile is covered on top of them. The first soft soil layer is placed on the geotextile to simulate a soft soil layer. A hard soil layer is laid on top of the first soft soil layer to simulate a hard crust stratum; Acoustic emission sensors were arranged on the hard soil layer; A second layer of soft soil is laid on top of the hard crust layer to simulate the soft crust deposited on the actual seabed surface. Install the pile poles and pile shoe models, and connect the water bladder system; The pressure of the water bladder system is brought to a preset value to simulate the overburden pressure of the formation. According to the experimental mode, control parameters and control curves are sent to the hydraulic control system. The hydraulic cylinder is controlled to drive the pile shoe model to insert into the first soft soil layer according to the set mode. The displacement signal, thrust signal, water bladder pressure signal and acoustic emission signal of the pile rod are collected in real time. When the pile shoe model penetrates into the second soft soil layer to a preset depth, the experiment is completed. The motion control mode of the pile shoe model is speed mode or thrust mode. Based on the acoustic emission signals, the acoustic emission signal characteristics during the puncture process of hard crustal strata are determined to assist in puncture prediction during offshore platform pile driving operations.

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