CN101464481A - Resistivity monitoring method and apparatus for sea floor erosion/deposition dynamic process - Google Patents

Abstract

The invention relates to a specific resistance monitoring device used in a seabed erosion-deposition dynamic process, which comprises a detecting sensing device, an automatic control recording device and an outer shell thereof, and is characterized in that a plurality of electrodes fixed on an outer wall of a PVC pipe in an equidistant manner are arranged on the detecting sensing device; in the PVC pipe, a lead penetrates through the wall of the PVC pipe and leads the electrodes into the automatic control recording device; a force bearing shaft passes through the outer shell of the automatic control recording device and an axle wire of the PVC pipe, is connected with a conical head on the bottom of the PVC pipe, and is fixed on the top of the outer shell of the automatic control recording device through a shim block and a nut in a sealing manner; and the automatic control recording device comprises an electrode switch control module, a data acquisition module, a microprocessor, a USB mass storage, a battery and a clock module. The real-time, long-term and continuous monitoring on the seabed erosion-deposition dynamic changing process can be realized; and the specific resistance monitoring device is especially suitable for the monitoring on the seabed erosion-deposition dynamic process in common oceanic conditions and extreme oceanic conditions.

Description

Method and device for monitoring resistivity in dynamic process of seabed erosion

technical field

The invention belongs to the technical field of marine measurement, and relates to a method and a device for dynamic monitoring of the seabed erosion process by dynamically and cyclically measuring the resistivity values of seawater and sediments within a certain range near the seabed interface to interpret changes in the position of the seabed interface.

Background technique

Seabed sediments will be eroded or deposited under the action of seawater. These two processes are dynamic and may occur in calm sea conditions and extreme sea conditions such as storms. Since changes in the elevation of the seabed interface directly reflect the erosion or deposition of the seabed, the most commonly used techniques and methods for monitoring seabed erosion and deposition are as follows:

One is the application of photoelectric sensor probe device. Multiple photosensitive elements are distributed on the probe rod to convert sunlight into electrical signals for output display. After the probe rod is inserted into the sediment, some photosensitive elements are buried and cannot receive sunlight. When the seabed is eroded, the seabed sediment interface drops, and the exposed photosensitive elements When the number of elements increases, the electrical signal generated will be strengthened; if the sediment silts and the photosensitive element is blocked, the electrical signal generated will decrease, so as to judge the elevation change of the seabed interface. The strict requirements of this technology on the light source limit its application, and it is impossible to carry out dynamic real-time monitoring of the erosion and sedimentation of the underwater seabed interface around the clock, and the real-time performance is poor;

The second is to use acoustic technology. The underwater sound wave reflection probe is used to emit sound waves to the bottom of the water, and the seabed reflection surface elevation is calculated by the wave velocity and the time difference between the emission and reception of sound waves, and the seabed erosion and deposition are judged according to the change of height. When this method has a large amount of sand in the water, the reflected waves are chaotic, and it is difficult to judge the seabed elevation, and when used, a long cable will be exposed to the water. Therefore, in the sea conditions that have the most serious impact on erosion, such as strong winds and waves, the current velocity is high and the sand content in the water is high. This technology cannot record the elevation change of the seabed during the period, and the line is easily damaged.

To sum up, the current seabed erosion and deposition monitoring technology is difficult to achieve dynamic monitoring and recording of the erosion and deposition process, and is limited by sea conditions. Therefore, there is an urgent need to develop a device that can continuously and real-time monitor the dynamic process of seabed erosion and deposition under normal sea conditions and extreme sea conditions.

Contents of the invention

The purpose of the present invention is to provide a real-time, long-term, method and device for monitoring seabed erosion and deposition that can overcome the impact of extreme sea conditions - a method and device for monitoring the dynamic process of seabed erosion and deposition, to overcome the deficiencies of the prior art, and to Real-time monitoring of seabed erosion, deposition, erosion rate, etc.

The principle of this method is based on the significant difference in resistivity between seawater and sediments above and below the seabed interface. By collecting and analyzing the vertical resistivity values near the seabed, the position of the significant change in resistivity is obtained by analyzing the position of the seabed interface. , and comprehensively record and analyze the change of the interface position to realize the dynamic monitoring of the seabed erosion and deposition process.

The present invention is achieved in the following way: the present invention includes a detection sensing device, an automatic control recording device and its casing, and is characterized in that the detection sensing device has a plurality of electrodes fixed at equal intervals on the outer wall of the PVC pipe, and there are wires in the PVC pipe Penetrate the PVC pipe wall to guide the electrode into the automatic control recording device. A bearing shaft passes through the outer shell of the automatic control recording device and the central axis of the PVC pipe, and connects with the cone at the bottom of the PVC pipe. The top of the shell is sealed and fixed with a gasket and a nut, and the automatic control recording device has an electrode switch control module, a data acquisition module, a microprocessor, a USB mass memory, a battery and a clock module.

The advantages of the present invention: realize the real-time and continuous monitoring of the dynamic change process of seabed erosion; apply the circuit system with its own power supply and low power consumption, which is not affected by the weather; the USB storage design can store up to 100 megabytes of data, and implement Long-term monitoring; the design of the cone head makes it easy to penetrate, and it can well fix the device to prevent damage by seawater. It is suitable for monitoring the dynamic process of seabed erosion in general sea conditions and extreme sea conditions.

Description of drawings

Fig. 1, the overall structure schematic diagram of the present invention.

Fig. 2, the schematic diagram of the decomposition structure of the present invention.

Fig. 3 is a schematic diagram of connecting electrodes and wires of the detection and sensing device of the present invention.

Fig. 4 is a schematic diagram of the structural connection of the automatic control recording device of the present invention.

Fig. 5 is a schematic diagram of resistivity curves of seawater and sediment near the seabed measured by the present invention.

In the figure, 1. cone head, 2. bearing shaft, 3. PVC pipe, 4. electrode, 5. wire, 6. battery, 7. electrode switch control module, 8. microprocessor, 9. data acquisition module, 10. USB mass memory, 11. Clock module, 12. Gasket, 13. Nut, 14. Shell, 15. Automatic control recording device.

Detailed ways

As shown in Fig. 1, Fig. 2 and Fig. 3, the present invention includes a detection and sensing device, an automatic control recording device and its casing, and is characterized in that the detection and sensing device has a plurality of electrodes 4 fixed at equal intervals on the outer wall of the PVC pipe 3 In the PVC pipe 3, there is a wire 5 penetrating the PVC pipe wall to lead the electrode 4 to the automatic control recording device 15, and a load-bearing shaft 2 passes through the outer shell 14 of the automatic control recording device 15 and the central axis of the PVC pipe 3. The bottom end of the PVC pipe 3 is connected to the cone head 1, and is sealed and fixed with a gasket 12 and a nut 13 on the top of the shell 14 of the automatic control recording device 15. The automatic control recording device 15 has an electrode switch control module 7 and a data acquisition module 9 , microprocessor 8, USB mass memory 10, battery 6 and clock module 11.

Among them, the small hole where the wire passes through the PVC pipe is sealed and fixed with glue and sealing material, and the contact position between the cone head and the PVC pipe is also sealed and fixed. The electrode switch control module, data acquisition module, and USB mass in the recording device are automatically controlled. Both the memory and the clock module are connected to the microprocessor, and are controlled by the microprocessor, and the clock module is used for setting time parameters and recording collection time.

As shown in Figure 1 and Figure 2, the PVC pipe 3 can be selected with an outer diameter of 7.5cm and a wall thickness of about 3mm. The diameter of the bearing shaft can be 3cm. Both the bearing shaft and the cone head are made of alloy materials, which are corrosion-resistant and have high strength. The bearing shaft 2 is used to withstand the force of penetration and the action of waves in the water. Both ends are threaded, and the bottom end is screwed together with the cone head 1. The position passing through the casing 14 of the automatic control recording device is sealed with a gasket 12 of rubber material and fixed with a tightening nut 13. The cone head 1 is inserted into the deposit to Fixing device, its upper part is the round table that diameter and PVC pipe 3 internal diameters are suitable, inserts in the PVC pipe 3 to fix mutually, and screw hole is arranged on the round table, is convenient to load-bearing shaft 2 and is screwed on. The contact position between cone head 1 and PVC pipe 3 will be sealed with glue and epoxy resin. The length of cone head 1 is designed with three specifications of 1m, 2m, and 3m to ensure that the penetration depth is sufficient to ensure the stability of the recorder.

The shell 14 made of plastics is tubular, designed according to the diameter of the PVC pipe 3, and the top has a hole of the corresponding size of the bearing shaft so that the bearing shaft 2 passes through. The bottom of the casing 14 is in the shape of a circular tube and is socketed with the PVC pipe 3 of the detection and sensing device, and the gap at the contact position is treated with a sealant. The USB mass memory 10 in the automatic control recording device 15 makes the data storage capacity up to 100 megabytes, and the whole circuit system adopts a low power consumption design.

After the power switch is turned on, the instrument starts to work automatically, and the electrode switch module is controlled by the microprocessor 8, and the electrodes are connected to the data acquisition part sequentially and cyclically, and the collected signal is converted by the data acquisition part and sent to the microprocessor for processing to obtain the resistivity data , stored in USB mass memory; this circuit control realizes the measurement of the resistivity of the medium near the vertical section of the probe rod, that is, the resistivity of seawater and sediment, and analyzes the data to realize the dynamic monitoring of the process of seabed erosion and deposition .

The electrode 4 can be made of a copper wire with a diameter of 1 to 2 mm tightly wound around the PVC pipe to form a ring, welded together with the wire penetrating the pipe wall from the inside of the PVC pipe, and the other end of the wire is connected to the electrode switch module in the automatic control recording device. The small holes through which the wires exit are sealed with epoxy. The number of electrodes is 100, and the distance between adjacent electrodes is 1cm, but the number of electrodes can also be selected according to the monitoring needs, but it should not be less than 50 to ensure that the collected data is sufficient for analysis.

Taking 100 electrodes as an example below, the field measurement method of the present invention is as follows:

Set the parameters of the automatic control recording device, including collection frequency, start collection time and end collection time.

First, at the selected seabed monitoring site or station, the cone head 1 and the PVC pipe 3 are inserted into the seabed sediment by applying a penetrating force to the bearing shaft 2, and half (50) of the electrodes 4 are buried in the sediment , and the upper remaining electrode 4 will be exposed to seawater or air; then the casing 14 with the automatic recording device 15 inside is socketed and sealed on the top of the PVC pipe 3, and after the load-bearing shaft 2 passes through the top surface of the casing 14, a gasket 12 and nut 13 are tightened and sealed and fixed; then the instrument starts to work according to the set time; the microprocessor 8 controls the electrode switch module, using the symmetrical quadrupole method, that is, starting from the first electrode at the bottom to connect four electrodes at a time , first connect the first to fourth electrodes to the data acquisition module, the data acquisition module controls the power supply of the first and fourth electrodes, the second and third electrodes measure voltage or current, and process the data into resistivity data And store it in the USB mass storage; Then connect four electrodes from the second electrode up from the bottom, repeat the collection and storage until the last four electrodes, and cycle to the bottom to repeat the collection and storage process after the end. This method is called symmetry Quadrupole method. Within the set time, the above steps are repeated according to the set acquisition frequency to perform cyclic acquisition of resistivity values. That is, the resistivity measurement of seawater and sediments along the vertical section along the seabed is realized, and the vertical resistivity change curve within a certain range of the seabed interface is obtained.

After monitoring for a set period of time, the collected data is transferred to the host computer on the shore for analysis and processing, and the seabed interface is determined at the sudden change position of the resistivity value of the above-mentioned resistivity change curve, and compared with the seabed interface at different times position, the dynamic change of the seabed interface over time can be obtained, that is, the rate and total amount of seabed erosion and deposition can be obtained, and the real-time monitoring of the dynamic process of seabed erosion and deposition can be realized by using the resistivity method.

Claims (5)

1, a kind of sea bed erosion/deposition dynamic process resistivity monitoring device, comprise the detection sensing device, automatic controlling recording device (15) and shell (14) thereof, it is characterized in that, described detection sensing device has some electrodes (4) that equidistantly are fixed on pvc pipe (3) outer wall, having lead (5) to penetrate the pvc pipe wall in the pvc pipe (3) guides to electrode (4) in the automatic controlling recording device (15), a load axle (2) passes the axis of the shell (14) and the pvc pipe (3) of automatic controlling recording device (15), be connected with conehead (1) in pvc pipe (3) bottom, with pad (12) and nut (13) sealing and fixing, described automatic controlling recording device (15) has electrode switch control module (7) at the top of the automatic shell (14) of controlling recording device (15), data acquisition module (9), microprocessor (8), USB massage storage (10), battery (6) and clock module (11).

2, sea bed erosion/deposition dynamic process resistivity monitoring device as claimed in claim 1 is characterized in that above-mentioned electrode (4) around pvc pipe (3) surface is annular or short cylindrical.

3, sea bed erosion/deposition dynamic process resistivity monitoring device as claimed in claim 1 is characterized in that above-mentioned conehead (1) length is greater than 1/2 of load axle (2).

4, sea bed erosion/deposition dynamic process resistivity monitoring device as claimed in claim 1 is characterized in that the electrode switch control module (7) of above-mentioned automatic controlling recording device (15) realizes circle collection by microprocessor (8) control.

5, the method for utilizing sea bed erosion/deposition dynamic process resistivity monitoring device to monitor, it is characterized in that at first at selected sea bed monitoring place or erect-position, load axle (2) is applied penetrating power to be inserted conehead (1) and pvc pipe (3) in the sea bed sediment, and the electrode (4) of half quantity is imbedded in the sediment, top residue electrode (4) is exposed in seawater or the air; Shell (14) socket that will comprise automatic controlling recording device (15) then is sealed in pvc pipe (3) top, after load axle (2) passes shell (14) end face, tightens sealing and fixing with pad (12) and nut (13), starts working by the time instrument of setting again; Microprocessor (8) control electrode switch module (7), begin to connect four electrodes with symmetrical four-electrode method from first electrode of bottommost at every turn, promptly at first first is inserted data acquisition module to the 4th electrode, data acquisition module is controlled first and the 4th electrode power supply, second and the 3rd measuring voltage or electric current are with the treated USB massage storage that deposits in of data; Upwards connect four electrodes again from the bottom then since second electrode, repeated acquisition and storage, until last four electrodes, be recycled to bottom repeated acquisition storing process after the end, in the time that sets, constantly repeat above-mentioned steps according to the frequency acquisition that is provided with, promptly realized the seawater and the sedimental determination of resistivity of coastal bed vertical section, obtain in the seabed interface certain limit change in resistance curve on vertical as analyzing the multidate information that sea bed corrodes alluvial.

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