CN110749725A - A test device and test method for monitoring submarine landslide mass transport process - Google Patents

Abstract

A test device and a test method for monitoring the quality transport process of submarine landslides belong to the technical field of marine engineering. Based on the critical shear stress start-up condition and using the equivalent simulation method, a test device for monitoring the transport of submarine landslides to the water environment is proposed. Test method for effective testing and analysis of characteristic parameters of submarine landslide mass transport process. The test device proposed by the invention can monitor the changes in the mass transport process of the submarine landslide mass in real time, with convenient parameter acquisition and abundant data; the test method is theoretically enriched, easy to popularize, and helpful for landslide disaster evaluation and engineering facility design in marine engineering In addition, the present invention can not only be applied to the study of mass transport characteristics during the movement of submarine landslides, but also to the research of marine geological problems such as seabed sand waves and seabed sediment resuspension.

Description

A test device and test method for monitoring submarine landslide mass transport process

technical field

The invention belongs to the technical field of marine engineering, and relates to a device and method for monitoring and analyzing characteristics of submarine landslides in a laboratory, in particular to a test device and a test method for monitoring the quality transport process of submarine landslides.

Background technique

Submarine landslide is a marine soil disaster that occurs frequently, affects a wide range of areas, and is difficult to predict. After the submarine landslide is triggered by earthquakes, hydrate decomposition, waves and other factors, under the complex action of the water environment, it often shows staged evolution characteristics, including: slope instability, block slip, debris flow slip, Turbidity current flows, etc., the landslide bodies formed usually have the characteristics of large volume, fast speed, long slip distance, strong impact force, etc., and have a strong destructive effect on marine engineering facilities such as offshore platform foundations, submarine energy pipelines, cables, optical cables, etc. For example: in March 1977, a submarine oil pipeline of Texaco Company in the United States was damaged due to the impact of a submarine landslide, resulting in a large amount of crude oil leakage; in 2006, the submarine landslide caused the submarine optical cable in the Luzon Strait to break, interrupting the communication between China and Southeast Asian countries up to 12 hours. Therefore, analyzing the motion evolution characteristics of submarine landslides is of great significance for landslide hazard evaluation and engineering facility design.

At present, the phenomenon of turbidity current generated in the process of submarine landslide movement and the evolution from solid slider to turbid fluid movement are mainly due to the difference in density between the submarine landslide body and the water environment. Mass transfer will occur, a process often referred to as mass transport. However, how to quantitatively analyze the mass transport process during the movement of submarine landslides, and give the key characteristic parameters in this process (i.e., mass transport flux, representing the mass transport volume per unit time and unit area, kg/m ^{2 )} ·s), there is no reliable test device and test method, which is not conducive to the evaluation of submarine landslide disasters in marine engineering and the development of engineering facility design in submarine landslide prone areas.

SUMMARY OF THE INVENTION

Aiming at the current lack of devices and methods for effectively analyzing the mass transport process of submarine landslides, the present invention proposes a device and method for monitoring and analyzing the characteristics of submarine landslides in a laboratory. In the simulation method, a test device for monitoring the transport of submarine landslides to the water environment is proposed; then, the equivalent simulation relationship is determined and the test parameters are calibrated; finally, the test device is used to carry out the test, and according to etc. The establishment and parameter conversion of the valence simulation relationship and the test calibration relationship, and an effective test method for testing and analyzing the characteristic parameters of the submarine landslide mass transport process is proposed. This method is especially suitable for monitoring and analyzing the mass transport process of submarine landslides.

In order to achieve the above object, the technical scheme adopted in the present invention is:

A test device for monitoring the quality transport process of submarine landslides includes a power water supply part, a water environment part, a test part and other auxiliary parts.

The power water supply part is used to realize the function of constant flow speed regulation of water flow, and includes a water storage tank 1, a variable frequency water pump 2, a pipeline 4 and a nozzle 5. The water storage tank 1 is provided with a variable frequency water pump 2, and one end of the pipeline 4 passes through the inlet. The side of the water storage tank 1 is connected with the variable frequency water pump 2 , the other end is connected with the spout 5 , and the pipe 4 is provided with a water inlet valve port 3 .

The water environment part includes an environmental water tank 7 and a U-shaped groove 8 . The environmental water tank 7 is integrally placed on the upper part of the water collecting tank 15 , and the water collecting tank 15 is used to collect the turbid fluid flowing out of the water outlet valve 14 . A water outlet valve 14 is provided at the bottom of the environmental water tank 7 ; a bracket 13 is provided inside the environmental water tank 7 . The U-shaped groove 8 is integrally placed on the support 13 in the environmental water tank 7, and the bottom of the U-shaped groove 8 is covered with a layer of simulated seabed surface 11, and the seabed surface 11 is made of rough material; the test soil is placed in the U-shaped groove 8 Sample 10, spout 5.

The test part includes a flow meter 6, a soil resistivity measuring device 9 and a camera 12, and its core component is the soil resistivity measuring device 9, which has the functions of power supply and current monitoring, and is used for real-time monitoring of soil samples during the test. quality changes. The flowmeter 6 is installed on the pipeline 4 of the variable frequency water pump 2 and the spout 5, and the soil resistivity measuring device 9 is inserted into the interior of the test soil sample 10 from the side; the camera 12 is installed on the spout 5 and the test soil sample 10. Location.

Said other auxiliary parts include a water collecting tank 15 , a computer, a bracket 13 , and a simulated seabed surface 11 .

Further, the power of the variable frequency water pump 2 is 18-180W, ten-stage variable frequency control, the maximum flow is 15000L/h, and the maximum lift is 7m; under the control of the variable frequency water pump 2, the corresponding water flow speed range of the power water supply part: 1.16-2.05m/s .

Further, the flowmeter 6 adopts an ultrasonic flowmeter, which is suitable for measuring the flow velocity within a range of ±0.01m/s～±25m/s.

Further, the image resolution of the camera is 1920×1080, the imaging rate is 30 frames/second, and the camera is waterproof.

Further, the resistivity measuring device 9 establishes a relationship with the change of soil quality by changing the resistance difference presented by the soil in the applied electric field; The size of the type submerged test probe is 0.02m (length) × 0.00125m (diameter), and the electrode spacing is 0.0185m. The current test part of this part adopts a digital source meter, and the minimum current test accuracy is about 1pA, and it also provides power supply function .

A test method for monitoring the mass transport process of submarine landslides based on the above-mentioned test device, the test method is based on the critical shear stress starting condition, adopts an equivalent simulation method, relies on the test device, and according to the equivalent simulation relationship and The establishment of the test calibration relationship and the parameter conversion can realize the effective test and analysis of the characteristic parameters of the submarine landslide mass transport process, including: determining the equivalent simulation relationship before the test, determining the test calibration relationship, and the test soil sample preparation and the test during the test. Laying, preparation and start-up of test equipment, monitoring and recording of mass transport process, as well as sorting and monitoring data after the test, obtaining mass transport flux parameters, and applying them to relevant research and engineering design, specifically:

(1) Before the test, it is necessary to determine the equivalent simulation relationship and the test calibration relationship, wherein the equivalent simulation relationship refers to the relationship between the target analysis parameters before and after using the equivalent simulation method. For the submarine landslide mass transport process targeted by the present invention In other words, the target analysis parameter is the mass transport flux at the soil-water contact interface of the submarine landslide, so the equivalent simulation relationship determined here is the relationship between the mass transport flux parameters before and after the equivalent simulation, and the determination process adopts numerical values. method, the results of the velocity field and shear stress field at the soil-water interface before and after the equivalent simulation are given, and then the quantitative relationship before and after the equivalent simulation can be determined according to the critical shear stress initiation conditions in the mass transport process; The test calibration relationship is the relationship between the soil resistivity test results and the mass transport flux parameters in the test, and the soil resistivity measuring device 9 is used to calibrate the conversion relationship between the two.

(2) After the start of the test, the preparation and laying of the test soil samples are carried out first. The main requirement for the preparation of the test soil samples 10 is to prepare a uniform, repeatable soil sample that meets the characteristics of typical marine soil, and then lay it on the U-shaped groove 8; then, carry out the preparation and start-up of the test device; finally, monitor and record the quality transportation process through the test part. Wherein, the preparation and start-up process of the above-mentioned test device are:

First, close the water inlet valve 3 tightly, and fill the water storage tank 1 with water; place the test soil sample 10 in the U-shaped groove 8; insert a soil resistivity measuring device 9 on the side of the test soil sample 10, which uses a probe The soil resistivity measuring device 9 is activated to enter the working state of power supply and current monitoring.

Next, close the water outlet valve 14 tightly, and fill the environmental water tank 7 with water, so that the test soil sample 10 is completely in the water environment; When the working frequency is stable, the water in the water storage tank 1 flows through the pipeline 4 at a constant flow rate, and is ejected from the nozzle 5 to act on the test soil sample 10, wherein the flow rate of the water flow is monitored in real time by the flow meter 6, and the water outlet valve 14 is opened; With the continuous shearing action of the water flow, the mass transport process at the contact interface between the test soil sample 10 and the water gradually begins to form a suspended particle turbidity flow. This process can be monitored by the camera 12, wherein the camera has a waterproof function; until the soil resistance When the soil sample within the range of the electric field formed by the rate measuring device 9 is completely lost (that is, the current does not change any more), the test is stopped.

Finally, sort out the various results recorded by the flow meter 6, the soil resistivity measuring device 9 and the camera 12. After the water samples in the water collection tank 15 are settled clean, they are re-injected into the water storage tank 1 to recycle the water resources and carry out the next group. test.

(3) After the test, organize the monitoring data, and convert the soil resistivity test results after the equivalent simulation obtained by monitoring into the prototype results according to the equivalent simulation relationship and test calibration relationship determined before the test, so as to obtain the quality transport information. This parameter can be used in related research and engineering design.

The equivalent simulation method is to simulate the movement process of the dynamic submarine landslide body in the static water environment under the real state, and equivalently simulate the change process of the static landslide body under the action of the dynamic water flow. Based on the critical shear stress initiation condition that occurs in the mass transport process (that is, once the current shear stress at the contact interface between the submarine landslide mass and the water environment is greater than the critical shear stress of the marine soil material, the submarine landslide mass will be in the soil-water contact surface. The soil particles at the interface will enter the water and form a suspended turbidity flow), and the mass transport characteristics at the soil-water interface are equivalent.

For the determination of the equivalent simulation relationship, a computational fluid dynamics numerical method is used, which is suitable for multiphase flow simulation analysis, and the current commercial computational fluid dynamics numerical software (for example: ANSYS-CFX software) can be selected as the calculation software. Through this method, the results of the velocity field and shear stress field at the soil-water contact interface before and after the equivalent simulation are given, and then the quantitative relationship before and after the equivalent simulation can be determined according to the critical shear stress initiation conditions during the mass transport process.

The purpose of determining the test calibration relationship is to convert between the soil resistivity test results and the mass transport flux parameters in the test. Before the test starts, a soil resistivity measuring device needs to be used to calibrate the conversion relationship between the two. Similar calibration tests are often used in laboratory experiments.

The beneficial effects of the invention are as follows: the test device can monitor the changes of the mass transport process of submarine landslide bodies with different flow velocity conditions and different properties in real time, the parameters can be easily obtained, and the amount of data is rich; the test method is theoretically enriched and easy to popularize. On the theoretical basis of the shear stress starting condition, the equivalent simulation method is adopted, relying on the test device, and according to the establishment of the equivalent simulation relationship and the test calibration relationship and parameter conversion, the effective performance of the characteristic parameters of the submarine landslide mass transport process has been successfully realized. The test and analysis are helpful for landslide disaster evaluation and engineering facility design in marine engineering; in addition, the invention can not only be applied to the study of mass transport characteristics during the movement of submarine landslides, but also can be applied to submarine sand waves and submarine sediments In the study of marine geological problems such as resuspension of matter.

Description of drawings

Fig. 1 is a test device diagram of the present invention;

Fig. 2 is the test method flow chart of the present invention;

In the picture: 1 water storage tank; 2 variable frequency water pump; 3 inlet valve port; 4 pipeline; 5 spout; 6 flow meter; 7 environmental water tank; 8U-shaped tank; 9 soil resistivity measuring device; Bed surface; 12 cameras; 13 brackets; 14 water outlet valve ports; 15 water collection tanks.

Detailed ways

The specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

A test device for monitoring the quality transportation process of submarine landslides, as shown in Figure 1, includes a power water supply part, a water environment part, a test part and other auxiliary parts, wherein the power water supply part is higher in altitude than the water environment part. The power water supply part is used to realize the function of constant flow speed regulation of water flow, and includes a water storage tank 1, a variable frequency water pump 2, a pipeline 4 and a nozzle 5. The water storage tank 1 is provided with a variable frequency water pump 2, and one end of the pipeline 4 passes through the inlet. The side of the water storage tank 1 is connected with the variable frequency water pump 2 , the other end is connected with the spout 5 , and the pipe 4 is provided with a water inlet valve port 3 . The water environment part includes an environmental water tank 7 and a U-shaped groove 8 . The environmental water tank 7 is integrally placed on the upper part of the water collecting tank 15 , and the water collecting tank 15 is used to collect the turbid fluid flowing out of the water outlet valve 14 . A water outlet valve 14 is provided at the bottom of the environmental water tank 7 ; a bracket 13 is provided inside the environmental water tank 7 . The U-shaped groove 8 is integrally placed on the bracket 13 in the environmental water tank 7, and the bottom of the U-shaped groove 8 is covered with a layer of simulated seabed surface 11, and the seabed surface 11 is made of rough material; the test soil is placed in the U-shaped groove 8 Sample 10, spout 5. The test part includes a flow meter 6, a soil resistivity measuring device 9 and a camera 12, and its core component is the soil resistivity measuring device 9, which has the functions of power supply and current monitoring, and is used for real-time monitoring of soil samples during the test. quality changes. The flowmeter 6 is installed on the pipeline 4 of the variable frequency water pump 2 and the spout 5, and the soil resistivity measuring device 9 is inserted into the interior of the test soil sample 10 from the side; the camera 12 is installed on the spout 5 and the test soil sample 10. Location. Said other auxiliary parts include a water collecting tank 15 , a computer, a bracket 13 , and a simulated seabed surface 11 .

The preparation and start-up process of the above-mentioned test device is as follows: firstly, close the water inlet valve port 3 tightly, and fill the water storage tank 1 with water; lay the test soil sample 10 in the U-shaped groove 8, and the U-shaped groove 8 is placed in the environmental water tank as a whole. On the bracket 1 in 7, and the bottom of the U-shaped groove is covered with a layer of simulated seabed surface 11, the seabed surface 11 should be made of rough material; the soil resistivity measuring device 9 is inserted into the side of the test soil sample 10, and the device should use The probe-type submerged test probe and the accurate current recording component activate the soil resistivity measuring device 9 to enter the working state of power supply and current monitoring. Tightly close the water outlet valve 13, and fill the environmental water tank 7 with water, so that the test soil sample 10 is completely in the water environment; then, start the variable frequency water pump 2 to the target flow rate gear. Under the conditions of each gear, the variable frequency water pump 2 works The frequency should be stable, then the water in the water storage tank 1 flows through the pipeline 4 at a constant flow rate, and is ejected from the nozzle 5 to act on the test soil sample 10. The flow rate of the water flow is monitored in real time by the flow meter 6, and the water outlet valve 14 is opened; Due to the continuous shearing action of the water flow, the mass transport process at the contact interface between the test soil sample 10 and the water gradually begins to form a suspended particle turbidity flow. This process can be monitored by the camera 12, and the camera should have a waterproof function; until the soil resistivity All soil samples within the range of the electric field formed by the measuring device 9 are lost (that is, the current does not change), and the test is stopped; finally, the various results recorded by the flow meter 6, the soil resistivity measuring device 9 and the camera 12 are sorted, and the water collection tank is to be After the water sample in 15 is settled cleanly, it is re-injected into the water storage tank 1 to recycle the water resources and carry out the next set of experiments.

Further, the size of the water storage tank is 1.4m×0.8m×0.8m, the size of the U-shaped groove is 1.0m×0.3m×0.2m, and the size of the water environment box is 1.4m×0.7m×0.6m. The resistivity measurement device 9 changes the resistance difference presented by the soil in the applied electric field, and establishes a relationship with the change of the soil quality; the two-phase electrode method is used for the double-probe soil test, and the probe-type soil test is used. The size of the probe is 0.02m (length) × 0.00125m (diameter), and the electrode spacing is 0.0185m.

A test method for monitoring the quality transport process of submarine landslides based on the above-mentioned test device, as shown in Figure 2:

(1) Before the test, it is necessary to determine the equivalent simulation relationship and the test calibration relationship, wherein the equivalent simulation relationship refers to the relationship between the target analysis parameters before and after using the equivalent simulation method. For the submarine landslide mass transport process targeted by the present invention In other words, the target analysis parameter is the mass transport flux at the soil-water contact interface of the submarine landslide, so the equivalent simulation relationship determined here is the relationship between the mass transport flux parameters before and after the equivalent simulation, and the determination process adopts numerical values. method, the results of the velocity field and shear stress field at the soil-water interface before and after the equivalent simulation are given, and then the quantitative relationship before and after the equivalent simulation can be determined according to the critical shear stress initiation conditions in the mass transport process; The test calibration relationship is the relationship between the soil resistivity test results and the mass transport flux parameters in the test, and the soil resistivity measuring device 9 is used to calibrate the conversion relationship between the two.

(2) After the start of the test, the preparation and laying of the test soil samples are carried out first. The main requirement for the preparation of the test soil samples 10 is to prepare a uniform, repeatable soil sample that meets the characteristics of typical marine soil, and then lay it on the U-shaped groove 8; Then, carry out the preparation and start-up of the test device, and the specific implementation process refers to the elaboration of the test device in FIG. 1 above; Finally, the mass transport process is monitored and recorded, and the device components for monitoring and recording include the flow meter 6, Soil resistivity measuring device 9 and camera 12 .

(3) After the test, organize the monitoring data, and convert the soil resistivity test results after the equivalent simulation obtained by monitoring into the prototype results according to the equivalent simulation relationship and test calibration relationship determined before the test, so as to obtain the quality transport information. This parameter can be used in related research and engineering design.

The above-mentioned specific embodiments further describe the basic principles, main features and beneficial effects of the present invention in detail. It should be understood that the specific dimensions of each component in the test device of FIG. 1 and the composition of the test components, the process of determining the equivalent simulation parameters and the test calibration relationship in the test method flow of FIG. 2, etc., are not departing from the spirit and principles of the present invention. On the premise, the corresponding content extension such as size change and process adjustment should be included within the protection scope of the present invention.

Claims (5)

1. A testing device for monitoring the transportation process of landslide quality on the sea bottom is characterized by comprising a power water supply part, a water environment part, a testing part and other auxiliary parts;

the power water supply part is used for realizing a water flow constant-current speed regulation function and comprises a water storage tank (1), a variable-frequency water pump (2), a pipeline (4) and a nozzle (5), wherein the variable-frequency water pump (2) is arranged inside the water storage tank (1), one end of the pipeline (4) penetrates through the side surface of the water storage tank (1) and is connected with the variable-frequency water pump (2), the other end of the pipeline (4) is connected with the nozzle (5), and a water inlet valve port (3) is arranged on the pipeline (4;

the water environment part comprises an environment water tank (7) and a U-shaped groove 8; the environment water tank (7) is integrally arranged at the upper part of the water collecting tank (15), and the water collecting tank (15) is used for collecting turbid fluid flowing out of the water outlet valve (14); the bottom of the environmental water tank (7) is provided with a water outlet valve (14); a bracket (13) is arranged inside the environmental water tank (7); the U-shaped groove 8 is integrally arranged on a bracket (13) in the environmental water tank (7), and a layer of simulated seabed surface (11) is paved at the bottom of the U-shaped groove 8; a test soil sample (10) and a nozzle (5) are placed in the U-shaped groove (8);

the testing part comprises a flowmeter (6), a soil body resistivity measuring device (9) and a camera (12), the core component of the testing part is the soil body resistivity measuring device (9), and the testing part has the power supply and current monitoring functions and is used for monitoring the quality change condition of a testing soil sample in the testing process in real time; the flowmeter (6) is arranged on the pipeline (4) of the variable frequency water pump (2) and the nozzle (5), and the soil body resistivity measuring device (9) is inserted into the test soil sample (10) from the side surface; the camera (12) is arranged at the position of the nozzle (5) and the position of the test soil sample (10), and the camera (12) has a waterproof function;

the other auxiliary parts comprise a water collecting tank (15), a computer, a bracket (13) and a simulated seabed surface (11).

2. The testing device for monitoring the sea-bottom landslide mass transportation process according to claim 1, wherein the power of the variable frequency water pump (2) is 18-180W, ten-stage variable frequency control is performed, the maximum flow is 15000L/h, and the maximum lift is 7 m; under the control of the variable frequency water pump (2), the power water supply part corresponds to the water flow speed range: 1.16-2.05 m/s.

3. The testing device for monitoring the sea bed landslide mass transportation process according to claim 1, wherein the flow meter (6) is an ultrasonic flow meter, and is applicable to a flow rate measurement range of ± 0.01m/s to ± 25 m/s.

4. The device for monitoring the sea bed landslide mass transportation process according to claim 1, wherein the resistivity measuring device 9 adopts a two-phase electrode method double-probe penetration test, a probe type penetration test probe is used, the size of the probe type penetration test probe is 0.02m in length, 0.00125m in diameter, the electrode spacing is 0.0185m, a digital source meter is adopted in a current test part of the device, the minimum current test precision is 1pA, and the device also provides a power supply function.

5. A test method for monitoring the submarine landslide mass transportation process based on the test device of any one of claims 1-4, which is characterized in that the test method is based on the critical shear stress starting condition, an equivalent simulation method is adopted, effective test and analysis of characteristic parameters of the submarine landslide mass transportation process can be realized based on the test device and according to establishment and parameter conversion of an equivalent simulation relation and a test calibration relation, and the specific steps are as follows:

(1) before testing, determining an equivalence simulation relation and a test calibration relation;

determining an equivalence simulation relationship, namely the relationship between the mass transport flux parameters before and after equivalence simulation, adopting a numerical method in the determination process, giving speed field and shear stress field results at soil-water contact interfaces before and after equivalence simulation, and determining a quantitative relationship before and after equivalence simulation according to the critical shear stress starting condition generated in the mass transport process; the test calibration relation is the relation between the soil body resistivity test result and the mass transport flux parameter in the test, and the conversion relation between the soil body resistivity test result and the mass transport flux parameter is calibrated by adopting a soil body resistivity measuring device (9);

(2) after the test is started, the test device is prepared and started, and the quality transportation process is monitored and recorded through the test part; the preparation and starting process of the testing device comprises the following steps:

firstly, preparing a closed water inlet valve port (3), and filling water into a water storage tank (1); laying a test soil sample (10) in a U-shaped groove 8; inserting a soil body resistivity measuring device (9) into the side surface of the test soil sample (10), and starting the soil body resistivity measuring device (9) to enter a power supply and current monitoring working state;

secondly, closing a water outlet valve (14), and filling water into the environmental water tank (7) to ensure that the test soil sample (10) is completely in the water environment; then opening a water outlet valve (14), starting the variable frequency water pump (2) to a target flow speed gear, wherein under the condition of each gear, the working frequency of the variable frequency water pump (2) is stable, so that the water in the water storage tank (1) flows through the pipeline (4) at a constant flow speed, is sprayed out from the nozzle (5) and acts on the test soil sample (10), and the flow speed of the water flow is monitored by the flowmeter (6) in real time; along with the continuous shearing action of water flow, the mass transportation process at the contact interface of the test soil sample (10) and the water gradually starts to form particle suspension turbidity current, and the process is subjected to image monitoring by a camera (12); stopping the test until the soil sample in the electric field range formed by the soil body resistivity measuring device (9) is completely lost, namely the current is not changed any more;

finally, various results recorded by the flowmeter (6), the soil body resistivity measuring device (9) and the camera (12) are sorted, after a water sample in the water collecting tank (15) is completely precipitated, the water sample is injected into the water storage tank (1) again, water resources are recycled, and a next group of tests are carried out;

(3) after the test is finished, monitoring data are collated, and the soil body resistivity test result obtained after the equivalent simulation after the monitoring is converted into a prototype result according to the equivalent simulation relation and the test calibration relation determined before the test, so that the quality transport flux parameter is obtained.

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