Monitoring probe rod applied to seabed liquefaction

Abstract

The invention discloses a monitoring probe rod applied to seabed liquefaction, and belongs to the technical field of ocean engineering. Which comprises a rod body (2), and a plurality of measuring mechanisms are sequentially arranged along the axial direction of the rod body (2), and is characterized in that each measuring mechanism comprises a plurality of groups of measuring plates (4), and the measuring plates (4) are telescopically arranged in the rod body (2) under the driving of a driving mechanism; a testing cavity (16) is arranged on the surface of the measuring plate (4), a floating plate (10) is arranged at the port of the testing cavity (16) in a floating manner, and a sensor for detecting the floating force of the floating plate (10) is arranged in the testing cavity (16). According to the monitoring probe rod applied to seabed liquefaction, the telescopic monitoring plate is arranged, the floating plate on the surface of the monitoring plate is utilized, shear stress brought by high-viscosity liquefied silty soil in a fluctuating state can push the floating plate to generate displacement, and monitoring of seabed shear stress is achieved through the sensor connected with the floating plate; therefore, the wave-induced seabed liquefaction can be further analyzed and researched.

Description

Technical Field

[0001] The invention discloses a monitoring probe rod used for seabed liquefaction, belonging to the technical field of marine engineering. Background Art

[0002] The stability of the seabed, as the bottom of the ocean, is of vital importance to marine engineering, marine environment and human activities. The seabed may be affected by various natural or human factors, among which seabed liquefaction is a common phenomenon. In the actual marine environment, marine liquefaction has an important impact on engineering and environmental issues.

[0003] In the calculation models for seabed liquefaction in the existing technology, the seabed is often treated as a solid state. However, in the actual marine environment, the seabed is prone to wave-induced liquefaction under the action of strong waves. In fact, the liquefied seabed has become a fluid, and viscous fluctuations are its important fluid characteristics. The description of its movement and mechanical behavior should be carried out from the perspective of fluid mechanics. The gradual development of liquefaction depth from top to bottom observed in indoor water tank tests, centrifuge tests and field monitoring is an important feature of seabed wave-induced liquefaction.

[0004] At present, in order to mathematically describe the characteristics of the gradual development of seabed wave-induced liquefaction from top to bottom, Sassa developed a moving boundary model combining the double-layer fluid theory and the porous elastoplastic model. Liu et al. considered the viscosity of liquefied soil on this basis. The proposed models all take the lower unliquefied seabed as a solid state and use the cyclic wave pressure exerted on the bottom by the upper liquefied seabed as the power source to explain the phenomenon that the liquefaction depth continues to develop downward. Although this scheme solves the problem of the gradual development of liquefaction downward, it only uses the wave pressure data on the bottom bed. After the liquefaction develops to a certain depth, the calculated liquefaction depth is still too small because the dragging and scouring effect caused by the large near-bottom horizontal velocity of the wave-induced liquefied soil is not considered, which does not conform to the physical essence of wave-induced seabed liquefaction.

[0005] For silty soil seabed, the viscosity of the soil after liquefaction is very high. According to the measurement of the viscosity coefficient of liquefied silty soil by the drag ball method and the falling ball method, its value is in the order of 1~10kPa·s. Due to the internal viscosity dissipation of high viscosity fluid, the wave capacity decreases sharply, and its wave pressure on the bottom is very small. Correspondingly, it is difficult for the lower non-liquefied seabed to accumulate higher pore water pressure due to dynamic response. The indoor water tank test observed the difference between the effect of clear water wave on the bottom bed and the effect of liquefied soil wave on the non-liquefied bottom bed: The effect of clear water wave on the bottom bed is mainly through the shear force exerted on the bottom bed surface by the near-bottom water flow. After the shear force acts on the bed surface, the soil particles are subjected to drag and lifting force and start to move. This is the mechanism of water flow scouring sediment in traditional knowledge. However, liquefied soil is a high-density fluid containing a large number of suspended soil particles (density can reach 1800 kg / m3 ), the horizontal movement of soil particles in the fluctuating liquefied soil near the bottom will exert force on the soil particles on the surface of the non-liquefied soil below it, thereby accelerating its start-up. That is, the fluctuating liquefied soil produces solid-solid particle friction on the non-liquefied soil below, which will change the traditional understanding of the mechanism of water flow scouring sediment.

[0006] Through indoor water tank tests, it was found that the horizontal velocity of the liquefied seabed at the interface between it and the underlying non-liquefied seabed is not zero. The highly viscous liquefied silty soil in a fluctuating state will inevitably exert a shear stress greater than that of the water on the surface of the underlying non-liquefied seabed, thereby dragging and scouring the underlying soil. This interfacial shear stress may be the driving force for the liquefaction depth of the silty soil seabed to continue to develop downward. At present, there is a lack of technical solutions for the detection of shear stress during seabed liquefaction.

[0007] The Chinese invention patent with application number 202410030707.0 and application date January 9, 2024, and the patent name "A seabed liquefaction deformation monitoring and early warning device and method" discloses a technical solution, in which a monitoring rod is provided, and an annular slidable monitoring cabin is provided to slide along the monitoring rod, in which a pore water pressure sensor and a soil pressure sensor for monitoring the upper soil of the seabed are provided, and the terminal system is further used to analyze the monitoring data and issue corresponding early warning information. However, in this technical solution, the slidable monitoring cabin is always located on the surface of the upper soil of the seabed, and in this technical solution, the shear stress caused by the high-viscosity liquefied silty soil in a fluctuating state is not monitored. Summary of the invention

[0008] The technical problem to be solved by the present invention is: to overcome the shortcomings of the prior art and provide a monitoring plate with a retractable arrangement, wherein the shear stress brought about by the high-viscosity liquefied silty soil in a fluctuating state will push the floating plate to displace, and the shear stress of the seabed is monitored by a sensor connected to the floating plate, so as to further analyze and study the wave-induced seabed liquefaction, thereby realizing a monitoring probe applied to seabed liquefaction.

[0009] The technical solution adopted by the present invention to solve its technical problems is: the monitoring probe rod applied to seabed liquefaction includes a rod body, and a plurality of measuring mechanisms are arranged in sequence along the axial direction of the rod body, and is characterized in that: the measuring mechanism includes a plurality of groups of measuring plates arranged in the rod body, and the measuring plates are arranged in the rod body in a radially telescopic manner under the drive of a driving mechanism; a test cavity is arranged on the surface of the measuring plate, a floating plate is floatingly arranged at the port of the test cavity, and a sensor connected to the floating plate and used to detect the floating force of the floating plate is arranged in the test cavity.

[0010] Preferably, the sensor is a tension and compression sensor, and a swing shaft is provided at the sensing end of the tension and compression sensor. The swing shaft extends upward to the floating plate and is vertically fixed to the floating plate.

[0011] Preferably, a supporting mechanism for supporting the floating plate is also provided on the side of the sensor.

[0012] Preferably, the support mechanism includes a track seat arranged on both sides of the sensor, and rollers are respectively clamped in the track seat. The roller includes two wheel bodies arranged at an interval, and a swing shaft is led out from between the two wheel bodies. The swing shaft extends to the lower surface of the floating plate and is vertically fixed.

[0013] Preferably, the driving mechanism includes a driving motor arranged at the top of the rod body, the motor shaft of the driving motor is coaxially fixed with the driving shaft, and the driving shaft extends downward to the lower part of the rod body; a driving disk corresponding to the monitoring plate is arranged on the driving shaft, the driving disk is an eccentric disk, and the driving disk is in contact with the monitoring plate.

[0014] Preferably, guide sleeves corresponding to the monitoring plates are arranged on the inner wall of the rod body, and the monitoring plates are located in the corresponding guide sleeves.

[0015] Preferably, a fixing platform is provided on the inner wall of the rod body and is arranged opposite to the guide sleeve one by one. A return spring is provided at each of the four corners of the monitoring plate, and the other end of the return spring is fixed to the surface of the fixing platform.

[0016] Preferably, a sand retaining membrane is provided at the gap between the floating plate surface and the test cavity, an annular sand retaining plate is also provided in the test cavity, and the sensor and the supporting mechanism are located inside the sand retaining plate.

[0017] Preferably, a plurality of detection holes are opened on the surface of the rod body along the axial direction of the rod body, and a pressure sensor is arranged in each detection hole.

[0018] Compared with the prior art, the present invention has the following beneficial effects: In the monitoring probe used for seabed liquefaction, a retractable monitoring plate is provided. By utilizing the floating plate on the surface of the monitoring plate, the shear stress brought by the high-viscosity liquefied silty soil in a fluctuating state will push the floating plate to displace. The shear stress of the seabed is monitored by using the sensor connected to the floating plate, so as to further analyze and study the wave-induced seabed liquefaction.

[0019] In the monitoring probe applied to seabed liquefaction, a positioning body is provided to avoid swinging of the driving shaft when it rotates, thereby improving the stability of the driving shaft.

[0020] A sand-trapping membrane is provided at the gap between the surface of the floating plate and the test cavity, and the gap between the floating plate and the test cavity is sealed by the sand-trapping membrane to prevent sand from the seabed from entering. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 Axonometric view of a monitoring probe used for seabed liquefaction.

[0022] Figure 2 A front view of a monitoring probe used for seabed liquefaction.

[0023] Figure 3 for Figure 2 AA section view.

[0024] Figure 4 for Figure 3 Middle BB section view.

[0025] Figure 5 for Figure 4 CC section view.

[0026] Among them: 1. drive motor 2, rod body 3, pressure sensor 4, monitoring board 5, drive shaft 6, guide sleeve 7, drive disc 8, earth-breaking cone 9, positioning body 10, floating plate 11, reset spring 12, fixed platform 13, sand-trapping membrane 14, swing shaft 15, swing shaft 16, test chamber 17, track seat 18, roller 19, tension and compression sensor 20, base 21, sand-trapping plate 22, guide groove. DETAILED DESCRIPTION

[0027] Figures 1 to 5 The best embodiment of the present invention is shown below in conjunction with the attached Figures 1 to 5 The present invention is further described.

[0028] like Figure 1~2 As shown, a monitoring probe for seabed liquefaction (hereinafter referred to as the monitoring probe) includes a rod body 2, which is a hollow structure. A driving motor 1 is arranged on the top of the rod body 2. The motor shaft of the driving motor 1 is coaxially fixed with a driving shaft 5. The driving shaft 5 extends downward along the axis of the rod body 2 to the lower part of the rod body 2. A positioning body 9 is arranged at the lower part of the rod body 2. The bottom of the driving shaft 5 is rotatably mounted at the center of the positioning body 9. By arranging the positioning body 9, the swing of the driving shaft 5 during rotation is avoided, and the stability of the driving shaft 5 is improved.

[0029] On the surface of the rod body 2, a plurality of detection holes are opened along the axial direction of the rod body 2, and a pressure sensor 3 is respectively arranged in each detection hole. In the rod body 2, a plurality of groups of monitoring plate mechanisms are sequentially arranged along the axial direction of the rod body 2, and each group of monitoring plate mechanisms includes two monitoring plates 4. The two monitoring plates 4 of each group are arranged on both sides of the rod body 2 along the radial direction of the rod body 2, and the two monitoring plates 4 of each group are arranged alternately up and down.

[0030] Each monitoring plate 4 is telescopically arranged in the rod body 2, and a guide sleeve 6 corresponding to the monitoring plate 4 is arranged on the inner wall of the rod body 2, and the monitoring plate 4 is placed in the corresponding guide sleeve 6. A driving disk 7 corresponding to each monitoring plate 4 is arranged on the driving shaft 5. When the driving shaft 5 is driven by the driving motor 1 to rotate, the driving shaft 5 drives all the driving disks 7 to rotate at the same time, and further drives all the monitoring plates 4 to be output from the surface of the rod body 2 along the radial direction of the rod body 2 through the driving disk 7.

[0031] Combination Figure 3 The driving disk 7 is an eccentric disk, so when the driving motor 1 rotates, the outer surface radius of the eccentric disk gradually increases, pushing the monitoring plate 4 to move along the radial direction of the rod body 2. A fixing platform 12 corresponding to the guide sleeve 6 is also provided on the inner wall of the rod body 2. The fixing platform 12 is arranged opposite to the corresponding guide sleeve 6. A reset spring 11 is respectively provided at the four corners of the monitoring plate 4. The other end of the reset spring 11 extends to the fixing platform 12 and is fixed on the surface of the fixing platform 12.

[0032] The four springs 11 fixed on the monitoring plate 4 are divided into two groups according to the up and down direction of the monitoring plate 4. The two groups of reset springs 11 pass through the upper and lower surfaces of the driving disk 7 respectively. The two reset springs 11 of each group pass through the two sides of the driving shaft 5 respectively. When the monitoring plate 4 is output from the surface of the rod body 2 under the action of the driving disk 7, the reset spring 11 is deformed. When the driving motor 1 rotates in the reverse direction, the spring 11 pulls the monitoring plate 4 into the rod body 2 by using the gradually decreasing radius of the outer surface of the eccentric disk.

[0033] like Figures 4 and 5 As shown, the monitoring board 4 includes a base 20, and an inclined surface is provided at the outer end of the base 20 to form a breaking cone 8, so that the monitoring board 4 can enter the seabed when it is output. The width of the breaking cone 8 along the radial direction of the rod body 2 is smaller than the width of the guide sleeve 6, so that after the monitoring board 4 returns to the rod body 2, the breaking cone 8 is located inside the guide sleeve 6 as a whole, preventing the sand in the seabed from entering the rod body 2. Guide grooves 22 are respectively provided on both sides of the base 20, and guide protrusions corresponding to the guide grooves 22 are provided on the inner wall of the guide sleeve 6, and the guide protrusions on the inner wall of the guide sleeve 6 are correspondingly snapped into the guide grooves 22.

[0034] A test cavity 16 is provided on the upper surface of the base 2, and a floating plate 10 is provided at the upper opening of the test cavity 16. The circumference of the floating plate 10 is spaced apart from the inner wall of the upper end of the test cavity 16. A sand-trapping membrane 13 is provided at the gap between the surface of the floating plate 10 and the test cavity 16, and the gap between the floating plate 10 and the test cavity 16 is closed by the sand-trapping membrane 13 to prevent sand from the seabed from entering.

[0035] A tension and compression sensor 19 is arranged at the center of the test cavity 16, and a transmission rod 14 is arranged at the measuring end of the tension and compression sensor 19. The transmission rod 14 extends vertically upward to the lower surface of the floating plate 10 and is vertically fixed to the lower surface of the floating plate 10. Track seats 17 are arranged on both sides of the tension and compression sensor 19, and a group of rollers 18 are arranged in each track seat 17. The roller 18 includes two wheel bodies arranged at intervals, and a swing shaft 15 is led out from between the two wheel bodies. One end of the swing shaft 15 is rotatable at the wheel shaft of the roller 18, and the other end of the swing shaft 15 extends vertically upward to the lower surface of the floating plate 10 and is vertically fixed to the lower surface of the floating plate 10. The wheel shaft of the roller 18 protrudes axially from the wheel bodies on both sides at the same time. After the wheel shaft protrudes from both ends of the roller 18, it is clamped in the track seat 17.

[0036] An annular sand shield 21 is also provided in the test chamber 16, and the tension and compression sensor 19 and the track seat 17 are located inside the sand shield 21. The signal lines of the pressure sensor 3 and the tension and compression sensor 19 can penetrate the side wall of the rod body 2 and be sealed and led out, and extend to the sea surface together with the power line and control line of the drive motor 1.

[0037] The specific working process and working principle are as follows: The monitoring probe is transported to the sea area to be monitored, and is sunk into the seabed of the pre-examination sea area. The driving motor 1 is controlled to rotate. When the driving motor 1 rotates, the radius of the outer surface of the eccentric disk gradually increases, and the monitoring plate 4 is pushed to move radially along the rod body 2, so that the monitoring plate 4 extends radially from the surface of the rod body 2, and the monitoring plate 4 is extended into the seabed by the earth-breaking cone 8 at the end of the monitoring plate 4.

[0038] The silt in the seabed applies pressure to the pressure sensor 3 on the surface of the rod body 2. At the same time, the monitoring plate 4 located in the seabed applies pressure to the floating plate 10 on the surface of the monitoring plate 4. When the seabed is in a fluctuating state, the shear stress brought by the high-viscosity liquefied silty soil in the fluctuating state will push the floating plate 10 to displace along the radial direction of the rod body 2. When the floating plate 10 is displaced by the shear stress, the shear stress is applied to the tension and compression sensor 19 through the transmission rod 14.

[0039] Since there are multiple groups of monitoring plates 4 arranged along the axial direction of the rod body 2, the shear stress at different depths in the seabed and the static pressure at different depths of the seabed are monitored from top to bottom. The data monitored by the tension and compression sensor 19 and the pressure sensor 3 are uploaded to the sea surface for recording, so as to further analyze and study the wave-induced seabed liquefaction.

[0040] The above is only a preferred embodiment of the present invention, and does not limit the present invention in other forms. Any technician familiar with the profession may use the above disclosed technical content to change or modify it into an equivalent embodiment with equivalent changes. However, any simple modification, equivalent change and modification made to the above embodiment according to the technical essence of the present invention without departing from the technical solution of the present invention still belongs to the protection scope of the technical solution of the present invention.

Claims

1. A monitoring probe for seabed liquefaction, comprising a rod body (2), with a plurality of measuring mechanisms arranged in sequence along the axial direction of the rod body (2), characterized in that: The measuring mechanism comprises a plurality of groups of measuring plates (4) arranged in a rod body (2); the measuring plates (4) are arranged in the rod body (2) in a retractable manner along the radial direction of the rod body (2) under the drive of a driving mechanism; a test cavity (16) is arranged on the surface of the measuring plate (4); a floating plate (10) is arranged in a floating manner at the port of the test cavity (16); and a sensor connected to the floating plate (10) and used for detecting the floating force of the floating plate (10) is arranged in the test cavity (16).

2. The monitoring probe for seabed liquefaction according to claim 1, characterized in that: The sensor is a tension and compression sensor (19), and a transmission rod (14) is arranged at the sensing end of the tension and compression sensor (19). The transmission rod (14) extends upward to the floating plate (10) and is vertically fixed to the floating plate (10).

3. The monitoring probe for seabed liquefaction according to claim 1 or 2, characterized in that: A supporting mechanism for supporting the floating plate (10) is also provided on the side of the sensor.

4. The monitoring probe for seabed liquefaction according to claim 3, characterized in that: The support mechanism comprises a track seat (17) arranged on both sides of the sensor, rollers (18) are respectively mounted in the track seats (17), the rollers (18) comprise two wheel bodies arranged at an interval, a swing shaft (15) is led out from between the two wheel bodies, and the swing shaft (15) extends to the lower surface of the floating plate (10) and is vertically fixed.

5. The monitoring probe for seabed liquefaction according to claim 1, characterized in that: The driving mechanism comprises a driving motor (1) arranged at the top of the rod body (2); the motor shaft of the driving motor (1) is coaxially fixed with a driving shaft (5); the driving shaft (5) extends downward to the lower part of the rod body (2); a driving disk (7) corresponding to the monitoring plate (4) is arranged on the driving shaft (5); the driving disk (7) is an eccentric disk, and the driving disk (7) is in contact with the monitoring plate (4).

6. The monitoring probe for seabed liquefaction according to claim 5, characterized in that: A guide sleeve (6) corresponding one to one with the monitoring plate (4) is arranged on the inner wall of the rod body (2), and the monitoring plate (4) is located in the corresponding guide sleeve (6).

7. The monitoring probe for seabed liquefaction according to claim 6, characterized in that: A fixing platform (12) is also provided on the inner wall of the rod body (2) and is arranged opposite to the guide sleeve (6). A return spring (11) is provided at each of the four corners of the monitoring plate (4), and the other end of the return spring (11) is fixed to the surface of the fixing platform (12).

8. The monitoring probe for seabed liquefaction according to claim 3, characterized in that: A sand retaining membrane (13) is provided at the gap between the surface of the floating plate (10) and the test chamber (16), and an annular sand retaining plate (21) is also provided in the test chamber (16), and a sensor and a supporting mechanism are located inside the sand retaining plate (21).

9. The monitoring probe for seabed liquefaction according to claim 1, characterized in that: A plurality of detection holes are provided on the surface of the rod body (2) along the axial direction of the rod body (2), and a pressure sensor (3) is provided in each detection hole.

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