CN115629219A - Underground water flow velocity and flow direction detection device and method - Google Patents

Abstract

The invention discloses a device and method for detecting groundwater flow velocity and direction. The method includes: placing the device in still water, where the water body in the still water is the extracted water sample to be tested, a magnetic ball transmitter emitting a magnetic ball, an electromagnetic transmitting coil and an electromagnetic receiving device. The coil works, based on the transient electromagnetic principle, the first position data of the magnetic ball at each moment is obtained; the device is placed downhole, and the magnetic ball is emitted by the magnetic ball transmitter, and the electromagnetic transmitting coil and the electromagnetic receiving coil work , based on the transient electromagnetic principle, the second position data of the magnetic ball at each moment is obtained; the second position data is subtracted from the first position data at the corresponding time to obtain the motion data of the magnetic ball under the action of water flow, according to the motion of the magnetic ball data to determine the velocity and direction of groundwater flow. The invention can quickly and accurately detect the flow velocity and direction of the groundwater, and is especially suitable for the groundwater environment with turbid water quality.

Description

Device and method for detecting groundwater flow velocity and direction

technical field

The invention relates to the technical field of hydrogeological parameter testing, in particular to a device and method for detecting groundwater flow velocity and direction.

Background technique

Groundwater seepage has a wide demand in many fields of hydrogeology, engineering geology, and environmental geology. Groundwater seepage is analogized to the constitutive equation of hydrogeological science, which is the focus of groundwater scientific research. Groundwater seepage is often the main cause of geological disasters in the field of engineering geology, such as landslides, debris flows, ground subsidence, and dam foundation piping leakage. Groundwater seepage causes soil solute migration and water-soluble pollutants to diffuse, and is also an influencing factor for soil and groundwater pollution remediation. As mentioned above, as the main characteristic parameters describing the groundwater seepage field, the real-time monitoring of groundwater velocity and direction is of great significance and has a wide range of applications.

In the prior art, CN201811417894.9 discloses a method for measuring groundwater flow velocity and dominant flow direction by using the direct current charging method. Compared with the prior art, the invention uses conditional tests to determine the potential and resistance change characteristics of the aquifer under various conditions and The impact of geomorphology and formation lithology on potential and electrical resistance; it is more reliable to determine the follow-up measurement plan according to the condition test; three boreholes are arranged in the survey area to comprehensively judge the flow direction of groundwater, with high reliability; centered on the borehole, 12 The electrodes are arranged in each direction, and the potential contour map is made by measuring the potential of the M pole. Different potential lines and different comparison schemes can be selected to obtain multiple sets of flow velocity and flow direction data, which increases the amount of data and reduces errors. The above technical solution is based on the DC charging method, and by setting multiple boreholes to obtain multiple sets of data to increase the amount of data and reduce errors, and increase the workload required for the detection of groundwater flow velocity and direction. Based on this, how to quickly and accurately measure the flow direction of groundwater when only one hole is drilled is a technical problem that needs to be solved urgently.

Contents of the invention

The object of the present invention is to provide a groundwater flow velocity and direction detection device and method to solve the technical problems existing in the background technology.

Therefore, the present invention provides a kind of underground water velocity flow direction detection method, and the technical scheme that it adopts is as follows:

According to the first aspect of the present invention, there is provided a groundwater flow velocity and direction detection device, the device includes a box body, a water flow channel is arranged in the middle of the box body, an electromagnetic transmitting coil is arranged below the water flow channel in the box body, An electromagnetic receiving coil and a magnetic ball transmitter, a magnetic ball receiver is arranged above the water flow channel in the box.

Further, a cable is connected to the outer upper end of the box, and the device is placed downhole through the cable.

Further, the magnetic ball launcher includes a magnetic ball storage tube, at least one magnetic ball is stored in the magnetic ball storage tube, and a magnetic ball thrust assembly is arranged at the bottom of the magnetic ball storage tube.

Further, the magnetic ball receiver includes a magnetic ball receiving tube, and the receiving port of the magnetic ball receiving tube is connected to the horn-shaped receiving end.

According to a second aspect of the present invention, a method for detecting groundwater flow velocity and direction is provided, the method comprising:

The device is placed in still water, the water body of the still water is the extracted water sample to be tested, the magnetic ball transmitter emits a magnetic ball, the electromagnetic transmitting coil and the electromagnetic receiving coil work, based on the transient electromagnetic principle, the obtained The first position data of the magnetic ball at each moment;

The device is placed downhole, the magnetic ball is emitted by the magnetic ball transmitter, the electromagnetic transmitting coil and the electromagnetic receiving coil work, and the second position data of the magnetic ball at each moment is obtained based on the transient electromagnetic principle;

The second position data is subtracted from the first position data at the corresponding time to obtain the motion data of the magnetic ball under the action of the water flow, and the flow velocity and direction of the groundwater are determined according to the motion data of the magnetic ball.

Further, the first position data of the magnetic ball at each moment is obtained based on the transient electromagnetic principle, including:

The electromagnetic transmitting coil is powered first and then cut off to generate an electromagnetic field;

The electromagnetic receiving coil measures the attenuation of the electromagnetic field and obtains the apparent resistivity values at different depths;

The first position data of the magnetic ball is determined according to the apparent resistivity values at different depths.

Further, the second position data of the magnetic ball at each moment is obtained based on the transient electromagnetic principle, including:

The electromagnetic transmitting coil is powered first and then cut off to generate an electromagnetic field;

The electromagnetic receiving coil measures the attenuation of the electromagnetic field and obtains the apparent resistivity values at different depths;

The second position data of the magnetic ball is determined according to the apparent resistivity values at different depths.

The beneficial effects of the present invention are: according to a method for detecting groundwater flow velocity and flow direction according to the embodiment of the present invention, the abnormal area is formed by launching magnetic balls in the sampled still water body and underground water body, and the abnormality at each time is detected according to the principle of transient electromagnetic Area position data, the abnormal area position data obtained in the downhole water body and the abnormal area position data in the still water body are simply calculated to quickly and accurately detect the flow direction of the groundwater flow, and the present invention can be launched by multiple magnetic balls to obtain multiple sets of The data ensures the amount of data, so that in the case of only one borehole, it can not only ensure the accuracy of detection, but also avoid the complicated operation of multiple boreholes, and can quickly and accurately detect the flow rate and direction of groundwater.

Description of drawings

In order to more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the following will briefly introduce the drawings that need to be used in the description of the specific embodiments or the prior art. Throughout the drawings, similar elements or parts are generally identified by similar reference numerals. In the drawings, elements or parts are not necessarily drawn in actual scale.

Fig. 1 shows a schematic structural diagram of a groundwater flow velocity and direction detection device according to an embodiment of the present invention.

Fig. 2 shows a flowchart of a method for detecting groundwater flow velocity and direction according to an embodiment of the present invention.

Fig. 3 shows a schematic diagram of the transient electromagnetic principle of the magnetic source.

FIG. 4 shows the first position data of the magnetic ball when the device is placed in still water, where the abscissa represents the distance between the magnetic ball and the origin (emission point) in the horizontal and vertical directions, respectively.

Fig. 5 shows the second position data of the magnetic ball when the device is placed in groundwater, where the abscissa represents the distance between the magnetic ball and the origin (emission point) in the horizontal and vertical directions, respectively.

Detailed ways

Embodiments of the present invention are described below through specific examples, and those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific implementation modes, and various modifications or changes can be made to the details in this specification based on different viewpoints and applications without departing from the spirit of the present invention. It should be noted that, in the case of no conflict, the following embodiments and features in the embodiments can be combined with each other.

In the description of the present invention, unless otherwise stated, the meaning of "plurality" is two or more; the terms "upper", "lower", "left", "right", "inner", "outer" , "front end", "rear end", "head", "tail", etc. indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than Nothing indicating or implying that a referenced device or element must have a particular orientation, be constructed, and operate in a particular orientation should therefore not be construed as limiting the invention. In addition, the terms "first", "second", "third", etc. are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

In the description of the present invention, it should be noted that unless otherwise specified and limited, the terms "connected" and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral Ground connection; it can be mechanical connection or electrical connection; it can be direct connection or indirect connection through an intermediary. Those of ordinary skill in the art can understand the specific meanings of the above terms in the present invention in specific situations.

The specific implementation manners of the present invention will be further described in detail below in conjunction with the accompanying drawings and embodiments.

An embodiment of the present invention provides a method for detecting groundwater flow velocity and direction. As shown in FIG. An electromagnetic transmitting coil 3 , an electromagnetic receiving coil 4 and a magnetic ball transmitter 5 are arranged below the water flow channel 2 in the box body 1 , and a magnetic ball receiver 6 is arranged above the water flow channel 2 in the box body 1 . As shown in Figure 2, the method includes:

Step S100, placing the device in still water, the water body of the still water is the extracted water sample to be tested, the magnetic ball transmitter emits a magnetic ball, the electromagnetic transmitting coil and the electromagnetic receiving coil work, based on the transient electromagnetic The principle is to obtain the first position data of the magnetic ball at each moment. The first position data includes the position and corresponding speed of the magnetic ball at this moment. Since the magnetic ball is in still water, after it is launched, it has an upward initial velocity and is only affected by the buoyancy of the water. Therefore, the magnetic ball The ball will move upwards and basically will not move with the water flow, that is, its speed will only have an upward velocity.

After completing step S100 , the magnetic ball is in the magnetic ball receiver 6 , and before performing step S200 , the magnetic ball should be reset into the magnetic ball emitter 5 .

Step S200, place the device downhole, emit a magnetic ball through the magnetic ball transmitter, the electromagnetic transmitting coil and the electromagnetic receiving coil work, and obtain the second position data of the magnetic ball at each moment based on the transient electromagnetic principle . The second position data includes the position and corresponding speed of the magnetic ball at this moment. In the flowing water, the magnetic ball has an upward initial velocity after it is launched, and is affected by the buoyancy and flow force of the water at the same time, so the magnetic ball will move along with the direction of the water flow while moving upward, that is, its Velocity can be divided into an upward velocity and a velocity along the direction of water flow.

It should be noted that the power for launching the magnetic ball and the operating parameters of the electromagnetic transmitting coil and the electromagnetic receiving coil in step S100 and step S200 should be the same.

Step S300, subtract the first position data corresponding to the second position data from the second position data to obtain the motion data of the magnetic ball under the action of the water flow, and determine the flow velocity and direction of the groundwater according to the motion data of the magnetic ball. Taking a certain moment as an example, the first position data is subtracted from the second position data, and the upward velocity in the velocity in the second position data is offset, that is, the influence of the buoyancy of the water body and the initial velocity of the magnetic ball is eliminated, and we can obtain Data on the movement of a magnetic ball along a water flow without the influence of buoyancy, which can be used to determine the velocity and direction of groundwater flow.

In some embodiments, in order to avoid magnetic field interference, when the device is placed downhole, the device is placed in a state of true north and south, and then the magnetic ball is emitted by the magnetic ball emitter.

In some embodiments, the first position data of the magnetic ball at each moment is obtained based on the transient electromagnetic principle, including: the electromagnetic transmitting coil is first powered and then powered off to generate an electromagnetic field; the electromagnetic receiving coil measures the attenuation of the electromagnetic field to obtain different The apparent resistivity value of the depth; according to the apparent resistivity value of different depths, the first position data of the magnetic ball is determined.

In some embodiments, the obtaining of the second position data of the magnetic ball at each moment based on the transient electromagnetic principle includes: the electromagnetic transmitting coil is first powered and then powered off to generate an electromagnetic field; the electromagnetic receiving coil measures the attenuation of the electromagnetic field to obtain different The apparent resistivity value of the depth; according to the apparent resistivity value of different depths, the second position data of the magnetic ball is determined.

It can be understood that the detection of the first position data and the second position data is based on the same principle and is detected in still water and flowing water environments, both of which utilize the transient electromagnetic principle. In general, the magnetic ball is used as an abnormal area, the electromagnetic field is generated by the electromagnetic transmitting coil, and the electromagnetic field is measured by the electromagnetic receiving coil to measure the attenuation of the electromagnetic field, that is, the position of the abnormal area is determined according to the apparent resistivity value. In this embodiment The volume of the magnetic ball is relatively small, and the center point of the magnetic ball can be selected as the position of the abnormal area. With the position data of the magnetic ball at each time, the corresponding speed value of the magnetic ball at each time can be determined. The speed value is Therefore, the magnitude and direction of the velocity of the magnetic ball can be determined. After determining the magnitude and direction of the velocity of the magnetic ball, based on step S300, the buoyancy of the water body and the initial velocity of the magnetic ball can be removed to accurately measure the flow velocity and direction of the groundwater. flow direction.

Combined with Figure 3, the specific working principle of transient electromagnetic is as follows:

When sending the return line to supply a current pulse square wave, at the moment when the rear edge of the square wave falls, a primary magnetic field propagating to the normal direction of the emission return line is generated. Under the excitation of the primary magnetic field, the geological body will generate eddy current, and in the primary field After disappearing, the vortex will not disappear immediately, it will have a transition (attenuation) process. The transition process generates an attenuated secondary magnetic field that propagates into the geological body, and the receiving loop receives the secondary magnetic field. The change of the secondary magnetic field will reflect the electrical distribution of the geological body. If the secondary induced electromotive force V(t) is measured according to different delay times, the characteristic curve of the secondary magnetic field decaying with time is obtained.

The transient electromagnetic field mainly propagates in the form of diffusion in the earth. In this process, the electromagnetic energy is consumed due to the direct propagation in the conductive medium. Due to the skin effect, the high frequency part is mainly concentrated near the wire frame, and its distribution range is below the source. Or the upper part, the lower frequency part spreads to the depth, and the distribution range gradually expands.

Propagation depth d:

Propagation velocity v _z :

t is the propagation time, σ is the medium conductivity μ ₀ is the magnetic permeability in vacuum.

The detection degree of the transient electromagnetic of the magnetic source is related to the resistivity of the covering layer of the transmitting magnetic moment and the minimum resolvable voltage.

From formula (2):

t＝2π×10 ^-7 h ² /ρ (3)

The relationship between time, surface resistivity and sending magnetic moment is:

M is the sending magnetic moment, _ρ1 is the surface resistivity, and η is the minimum resolvable voltage, and its size is related to the geometric and physical parameters of the target layer and the observation time period. Simultaneous formula (3), (4), can get:

The above formula is commonly used in field engineering to calculate the maximum detection depth formula. The detection degree of the transient electromagnetic of the magnetic source is related to the transmitting magnetic moment, the resistivity of the covering layer and the minimum resolvable voltage.

The apparent resistivity was calculated using the late formula:

In the formula

After obtaining the apparent resistivity value of the magnetic ball, how to determine the position of the magnetic ball is a prior art, which will not be described in detail in this embodiment.

In some embodiments, as shown in FIG. 1 , a cable 7 is connected to the outer upper end of the box body 1 , and the device is placed downhole through the cable 7 . The cable 7 can be connected to a telescopic mechanism, for example, one end of the cable 7 is set on a wire rope reel, and the cable 7 can be stretched by rotating the wire rope reel. Alternatively, an electric hoist and the like are connected through the cable 7 .

In some embodiments, as shown in FIG. 1 , the magnetic ball launcher 5 includes a magnetic ball storage tube 501, at least one magnetic ball 8 is stored in the magnetic ball storage tube 501, and the magnetic ball storage tube 501 The bottom is provided with a magnetic ball thrust assembly 502 . The upper end of the magnetic ball storage tube 501 is provided with a magnetic ball launch port 503. The thrust assembly 502 is an assembly that generates thrust to the magnetic ball 501, such as an electric push rod, a linear motor, a hydraulic push rod and other equipment. For example, no specific limitation is made here. In addition, it should be noted that the number of magnetic balls 8 can be one or more. When multiple magnetic balls are selected, all the magnetic balls 8 can be ejected at one time, or they can be ejected separately within a preset time interval. The magnetic balls 8 are ejected one by one to obtain multiple sets of first position data and second position data, so as to improve the detection accuracy of groundwater flow velocity and direction.

In some embodiments, as shown in FIG. 1 , the magnetic ball receiver 6 includes a magnetic ball receiving tube 601, and the receiving port of the magnetic ball receiving tube 601 is connected to a horn-shaped receiving end 602 to launch the magnetic ball The magnetic ball emitted by the device 5 is received, and the magnetic ball is reset to the magnetic ball storage tube 501 after step S100 and step S200 are completed, to be used in the next detection step.

The following embodiments of the present invention will be combined with specific experimental data to further illustrate the feasibility and progress of the present invention.

Carry out software simulation based on the method described in the above embodiment (the software used is surfer), the results obtained are as shown in Figure 4 and Figure 5, the first position data of the magnetic ball that the device is placed in still water shown in Figure 4, Figure 5 shows the second position data of the magnetic ball with the device placed in the groundwater. At t=0, since the magnetic ball is not launched, there is almost no magnetic body, so the background value is approximately equal to zero. After the magnetic ball is released, it moves under the impact of the water flow. Since the velocity of the groundwater flow is very small, it can be calculated as a uniform object. As shown in Figure 5, after the ball moves for a period of time, at T=1.35s, the moving length and azimuth can be read from Figure 5, as shown in Figure 5, the moving length is 0.862cm, and the moving speed is V=S/T=0.862/1.35 = 0.639 cm/s. The movement direction angle is 171.458730, and the movement azimuth is 180-171.458730=8.54127 degrees south by west, ie SW8.54127. The main purpose of measuring the first position data is to calibrate the device in still water to avoid the deviation of the center of the magnetic ball caused by the deviation of the launch angle, which will affect the detection of the groundwater flow velocity and direction. In this simulation, because it is simulated in surfer software, the first position data is basically 0, that is, the magnetic ball moves according to the preset speed and trajectory, and the center of the magnetic ball is perpendicular to the magnetic field line, and no abnormality occurs district. Therefore, in this experimental simulation, the second location data can be directly used as the flow velocity and direction of groundwater.

The above embodiments are only used to illustrate the present invention, but not to limit the present invention. Those of ordinary skill in the relevant technical field can make various changes and modifications without departing from the spirit and scope of the present invention. Therefore, all Equivalent technical solutions also belong to the category of the present invention, and the scope of patent protection of the present invention should be defined by the claims.

Claims (8)

1. The utility model provides an underground water velocity of flow direction detection device, a serial communication port, the device includes the box, the box middle part is provided with the rivers passageway, the box is internal the below of rivers passageway sets up electromagnetic emission coil, electromagnetic reception coil and magnetic ball transmitter, the box is internal the top of rivers passageway is provided with the magnetic ball receiver.

2. The groundwater flow velocity/direction detecting device as claimed in claim 1, wherein a cable is connected to an outer upper end of the box, and the device is placed downhole through the cable.

3. The groundwater flow velocity and direction detecting device according to claim 1, wherein the magnetic ball emitter comprises a magnetic ball storage pipe, at least one magnetic ball is stored in the magnetic ball storage pipe, and a magnetic ball thrust assembly is arranged at the bottom of the magnetic ball storage pipe.

4. The groundwater flow speed and direction detecting device according to claim 1, wherein the magnetic ball receiver comprises a magnetic ball receiving pipe, and a receiving opening of the magnetic ball receiving pipe is connected with a trumpet-shaped receiving end portion.

5. A groundwater flow speed and direction detecting method, based on the groundwater flow speed and direction detecting device as claimed in any one of claims 1 to 4, the method comprising:

the device is placed in still water, the water body of the still water is an extracted water sample to be detected, the magnetic ball emitter emits a magnetic ball, the electromagnetic transmitting coil and the electromagnetic receiving coil work, and first position data of the magnetic ball at each moment are obtained based on a transient electromagnetic principle;

the device is placed underground, the magnetic ball is transmitted through the magnetic ball transmitter, the electromagnetic transmitting coil and the electromagnetic receiving coil work, and second position data of the magnetic ball at each moment are obtained based on a transient electromagnetic principle;

and subtracting the first position data at the corresponding moment from the second position data to obtain the motion data of the magnetic ball under the action of water flow, and determining the flow speed and the flow direction of the underground water according to the motion data of the magnetic ball.

6. The groundwater flow speed and direction detecting method as claimed in claim 5, wherein when the device is placed in the well, the device is made to be in a state of north and south, and then the magnetic ball is launched by the magnetic ball launcher.

7. The groundwater flow speed and direction detecting method as claimed in claim 5, wherein the obtaining of the first position data of the magnetic ball at each time based on the transient electromagnetic principle comprises:

the electromagnetic transmitting coil is powered on and then powered off to generate an electromagnetic field;

the electromagnetic receiving coil measures the attenuation of the electromagnetic field to obtain apparent resistivity values of different depths;

first position data of the magnetic sphere is determined based on apparent resistivity values at different depths.

8. The groundwater flow speed and direction detecting method as claimed in claim 5, wherein the obtaining of the second position data of the magnetic ball at each time based on the transient electromagnetic principle comprises:

the electromagnetic transmitting coil is powered on and then powered off to generate an electromagnetic field;

the electromagnetic receiving coil measures the attenuation of the electromagnetic field to obtain apparent resistivity values of different depths;

and determining second position data of the magnetic ball according to the apparent resistivity values at different depths.

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