CN106154341A - A kind of nuclear magnetic resonance, NMR and transient electromagnetic integrative detection instrument and method of work - Google Patents

Abstract

The invention discloses a nuclear magnetic resonance and transient electromagnetic integrated detection instrument, which includes a host, a transmitting coil, a receiving probe and a host computer system. The host includes a transmitting module that outputs nuclear magnetic resonance excitation pulses and transient electromagnetic excitation pulses, and collects nuclear magnetic resonance The receiving module of the two kinds of response signals of transient electromagnetic and transient electromagnetic is a communication module that realizes the command and data interaction between the upper computer system and the host control module; the transmitting module provides pulse output to the transmitting coil, and the receiving module pre-processes the signal collected by the receiving probe Set filtering and amplification processing, and transmit the processed signal to the control module. The invention abandons the traditional single-frequency sine wave excitation method in the aspect of the emission of the nuclear magnetic resonance excitation pulse, thereby saving a bulky resonant circuit, and is beneficial to work in tunnels with complex construction conditions. The coil support designed by the present invention to carry multiple probes at the same time has the advantage of being able to meet the observation requirements of multi-probe arrays receiving simultaneously.

Description

A nuclear magnetic resonance and transient electromagnetic integrated detection instrument and working method

technical field

The invention relates to a nuclear magnetic resonance and transient electromagnetic integrated detection instrument and a working method.

Background technique

With the proposal and further implementation of the "One Belt, One Road" strategy, my country will build a large number of tunnel projects in railway and highway transportation, water conservancy and hydropower, energy mines, municipal engineering and other fields. With the emergence of a large number of deep and long tunnel projects built in mountainous and karst areas with complex terrain and geological conditions, water and mud inrush disasters in tunnels have shown the characteristics of "large buried depth, strong karst, high water pressure, and large flow" . How to directly, accurately and quantitatively identify the water quantity and occurrence information of the disastrous geological body in front of the tunnel face in the advance prediction of tunnel water and mud inrush has important guiding significance for the follow-up grouting sealing and other treatment work. Among them, the direct and quantitative prediction of the water volume of the disaster water source in front of the tunnel face is an urgent problem to be solved in the advance prediction of tunnel water and mud inrush.

At present, combining advance drilling, tunnel face geological sketch, surface reconnaissance and using comprehensive geophysical detection and interpretation methods has become a common idea for advanced prediction of tunnel water and mud inrush. Among the many survey geophysical methods, nuclear magnetic resonance detection is the only geophysical method that can directly determine the spatial distribution, water content and formation porosity of water-bearing bodies. NMR detection uses ungrounded loops to emit radio frequency electromagnetic waves with the same frequency (Larmor frequency) as the hydrogen proton resonance in water to excite and obtain groundwater NMR response signals. The water content and porosity information of the surrounding rock in a certain range in front of the tunnel face can be directly obtained by using the nuclear magnetic resonance detection technology to detect water directly in the tunnel, so as to realize the qualitative identification and quantitative prediction of the disaster source of water and mud inrush in the face of the tunnel . In addition to nuclear magnetic resonance detection, the transient electromagnetic method, which belongs to the electromagnetic induction electromagnetic method, can also transmit current pulses to the front of the drill face through an ungrounded return line; determine the electrical properties of the underground medium according to the received secondary field attenuation voltage Distribution structure and spatial form of underground good conductors. Since the inversion and data interpretation of nuclear magnetic resonance are dependent on the distribution information of the underground electrical structure, in recent years, the joint interpretation technology that uses the transient electromagnetic method to obtain a reasonable electrical model and guide the inversion of nuclear magnetic resonance has received extensive attention. Combining the characteristics and advantages of both, the research and application of nuclear magnetic resonance and transient electromagnetic joint interpretation technology in tunnels provides an effective way to solve the advanced prediction of water and mud inrush disasters in tunnels.

At present, the application of integrated geophysical joint interpretation technology in the advanced prediction of water and mud inrush in tunnels lacks special joint instruments and devices. The joint interpretation technology of nuclear magnetic resonance detection and transient electromagnetic method requires the use of two different instruments for data observation and collection. Specifically, the following issues exist:

First, the types of transmitted waveforms are different. The excitation pulse used in NMR detection is a single-frequency sinusoidal pulse, which belongs to the frequency domain waveform. The transmitted pulses used in the transient electromagnetic method include time-domain waveforms such as bipolar rectangular waves, bipolar half-sine waves, and bipolar trapezoidal waves. Two sets of emission modules or devices are required to complete the emission of excitation pulses for the two methods.

Second, the signal receiving methods are different. NMR detection belongs to the frequency-domain induction electromagnetic method, and the theoretical response signal is a single-frequency electromagnetic attenuation signal. Orthogonal lock-in amplification technology is usually used for the reception and conditioning of single-frequency attenuation signals. The NMR response signal entrains broadband electromagnetic noise in the space and becomes a narrow-band signal after quadrature lock-in amplification. The transient electromagnetic method belongs to the time-domain induction electromagnetic method, and the received attenuated voltage signal of the secondary field has rich harmonic components. The reception and conditioning of such wide-band electromagnetic signals usually use band-pass filtering with a certain pass band and multiple superimpositions, instead of using quadrature lock-in amplifier circuits.

Third, based on the waveform emission and response reception methods of traditional nuclear magnetic resonance detection and transient electromagnetic method, the combined instrument and device should adopt a distributed implementation method. In the process of implementation, two discrete modules are built in a set of instruments, which are responsible for the transmission and reception of nuclear magnetic resonance and transient electromagnetics, and the instrument system is complex.

Fourth, because the traditional nuclear magnetic resonance uses a single-frequency sinusoidal pulse to excite the nuclear magnetic resonance response of the underground water-bearing body, the transmitter of the instrument needs a bulky resonant capacitor module; thus the volume and weight of the instrument are greatly increased, which is not conducive to the tunnel in the complex construction environment. Development of advance forecasting of water and mud inrush.

To sum up, in order to overcome the deficiencies of the existing technology, a nuclear magnetic resonance and transient electromagnetic integrated detection instrument applied to the advanced prediction of water and mud inrush in tunnels was invented. The excitation pulse emission and response signal reception of the nuclear magnetic resonance and transient electromagnetic methods are realized through a set of devices. Therefore, it can provide new hardware support for the joint interpretation of nuclear magnetic resonance and transient electromagnetic, and better solve the problem of quantitative identification and prediction of water sources for water and mud inrush disasters.

Contents of the invention

In order to solve the above problems, the present invention proposes a nuclear magnetic resonance and transient electromagnetic integrated detection instrument and working method. The excitation pulse emission and the response signal reception of the two methods of variable electromagnetic.

In order to achieve the above object, the present invention adopts the following technical solutions:

A nuclear magnetic resonance and transient electromagnetic integrated detection instrument, including a host, a transmitting coil, a receiving probe and a host computer system, the host includes a transmitting module that outputs nuclear magnetic resonance excitation pulses and transient electromagnetic excitation pulses, and collects nuclear magnetic resonance and transient electromagnetic The receiving module for two kinds of response signals, the communication module for realizing the command and data interaction between the upper computer system and the host control module, the control module for controlling the receiving module, the transmitting module and the communication module, and the power supply module for power supply;

The transmitting module provides pulse output to the transmitting coil, and the receiving module performs pre-filtering and amplification processing on the signal collected by the receiving probe, and transmits the processed signal to the control module to realize the emission of nuclear magnetic resonance and transient electromagnetic excitation pulses and response signal reception.

The transmitting coil includes a coil support and a transmitting wire. The transmitting coil is arranged on the coil support. The transmitting module receives a transmitting command from a host computer and controls the transmitting coil to transmit transient electromagnetic excitation pulses and nuclear magnetic resonance excitation pulses.

The outer contour of the coil bracket is square, and the inside of the bracket is a rice-shaped structure. There are nine probe fixing holes for fixing the receiving probes on the bracket. The probe fixing holes are evenly distributed on the rice-shaped structure bracket, which can carry out multiple probe Array reception.

The emitted nuclear magnetic resonance excitation pulse is a bipolar periodic square wave pulse at the Larmor frequency; the emitted transient electromagnetic excitation pulse is a bipolar rectangular wave pulse with an adjustable duty ratio.

The transmitting circuit includes a bridge-type IGBT transmitting circuit, and each IGBT is reversely connected with a diode in parallel.

Segmented joints are arranged on the transmitting wire, which can be flexibly adjusted by changing the length of the transmitting wire and the number of turns of the transmitting coil.

The control module of the host includes a host MCU, a clock circuit and a self-check circuit, wherein the clock circuit provides the clock frequency required for the host MCU to work, and the self-check circuit realizes the power-on self-check of the system, and the result of the self-check Upload to the host computer.

A kind of working method based on above-mentioned instrument, comprises the following steps:

(1) Use the square wave NMR excitation pulse to excite the NMR response in water: Calculate the emission frequency of the emission pulse according to the measured magnetic induction of the geomagnetic field, use the square wave NMR excitation pulse to excite the NMR response in the water, and trigger in the emission module The circuit controls the turn-on and turn-off of the IGBT in the launch bridge according to the received launch sequence;

(2) Acquisition and extraction of NMR response signals for tunnel water inrush and mud inrush: After the pulse is turned off, the control module sends a signal acquisition command to the receiving module and the receiving probe, performs preliminary filtering on the collected NMR response signals, and inputs the collected signals to The analog-to-digital conversion circuit of the receiving module completes the digitization of the signal;

(3) Acquisition and extraction of transient electromagnetic response signals for water and mud inrush in tunnels: Transient electromagnetic generators are excited by bipolar rectangular wave pulses with adjustable duty ratios. After the forward or reverse excitation pulses are turned off, the control module sends The receiving module and the receiving probe send signal acquisition commands to filter and process the acquired NMR response signals.

In the step (1), the bipolar periodic square wave pulse with the Larmor frequency is used to excite the hydrogen protons in the water body in front of the face of the tunnel by nuclear magnetic resonance.

In the step (1), the control module generates a transmission sequence according to the calculated transmission frequency and sends it to the transmission module, and the trigger circuit in the transmission module controls the conduction of the IGBT in the transmission bridge according to the received transmission sequence. on and off.

In the step (1), the square wave pulse frequency is the Larmor frequency of hydrogen protons in the water in the survey area, the pulse form is a bipolar periodic square wave pulse, and the frequency spectrum of the pulse only has fundamental wave components and odd harmonics portion.

In the step (2), the control module filters the signal to extract the envelope signal of the narrowband NMR response signal, and the response signal is uploaded to the host computer system through the communication module for storage and recording.

The beneficial effects of the present invention are:

(1) The present invention abandons the traditional single-frequency sine wave excitation mode when designing, thereby eliminating the bulky resonant circuit, the square wave nuclear magnetic resonance excitation pulse and the bipolar rectangular wave with adjustable duty cycle The pulse is realized through a set of transmission loops, which improves the transmission efficiency;

(2) In the present invention, the transmission circuit composed of high-power bipolar thyristor and related trigger circuit is small in size, high in control precision and easy to realize electrical insulation. The launch module design scheme proposed by the present invention can effectively reduce the weight of the launch module, reduce the volume of the launch module, and is beneficial to work in tunnels with complex construction conditions;

(3) The present invention adopts an all-digital signal acquisition and processing method. After the two kinds of response signals of nuclear magnetic resonance and transient electromagnetic are amplified by the pre-filter of the probe, they are converted into digital signals through analog-to-digital conversion, and the response signals are digitized. The digital filter program processing in the advanced signal processing chip, this all-digital processing method has the advantages of high precision, strong anti-interference ability and can be controlled by the program;

(4) The present invention also reduces the hardware purchase cost and the volume of the signal receiving module by replacing the traditional hardware filter circuit with a digital filter;

(5) The present invention designs a coil support capable of carrying multiple probes at the same time, which can meet the observation requirements of multi-probe arrays for simultaneous reception and improve observation efficiency; in addition, the working mode of multi-probe arrays for simultaneous reception avoids multiple transmissions The error between the transmitted waveforms when receiving at different points under certain conditions is more in line with the theoretical simulation situation. The coil support is made of polyoxymethylene plastic, which is durable and can be disassembled and assembled for convenient construction.

Description of drawings

Fig. 1 is a system block diagram of the present invention;

Fig. 2 is a structural diagram of a transmitting coil support of the present invention;

Fig. 3 is a schematic diagram of the working principle of the present invention.

Among them, 1. A-type bracket connector, 2. B-type bracket connector, 3. C-type bracket connector, 4. Probe fixing hole, 5. Fixing bolt, 6. Pozi-shaped bracket rod, 7. External bracket rod .

detailed description:

The present invention will be further described below in conjunction with the accompanying drawings and embodiments.

As shown in Figure 1, a nuclear magnetic resonance and transient electromagnetic integrated detection instrument for advanced prediction of tunnel water and mud inrush is composed of a host, a transmitting coil, a transmitting power supply, a set of receiving probes, and a host computer system. The host includes a transmitting module, a receiving module, a power supply module, a control module and a communication module. The control module of the host is composed of a host MCU, a clock circuit and a self-test circuit. The host MCU selects a high-performance embedded control chip, which is responsible for controlling each module of the host to realize corresponding functions. The clock circuit provides the clock frequency required for the work of the host MCU. The operating frequency of the entire host system is ultimately determined by the clock circuit. The self-inspection circuit realizes the instrument's power-on self-inspection, and uploads the result of the self-inspection to the host computer system. The data and command communication between the host computer and the upper computer system and each module of the host computer is completed through the communication bus. Each module of the host has the following functions:

(1) The emission module realizes the emission of two kinds of excitation pulses of tunnel core magnetic resonance and transient electromagnetic. As the core module of the nuclear magnetic resonance and transient electromagnetic integrated detection instrument, the transmitting module uses a set of transmitting circuits to realize the emission of excitation pulses by both nuclear magnetic resonance and transient electromagnetic methods. The transmitted NMR excitation pulse is a bipolar periodic square wave pulse at the Larmor frequency. The emitted transient electromagnetic excitation pulse is a bipolar rectangular wave pulse with adjustable duty cycle. The core of the transmitting circuit is a bridge circuit composed of high-power insulated gate bipolar thyristors (IGBTs) and related trigger control circuits. The transmitting module receives the transmitting command from the upper computer to control the on and off of the IGBT in the transmitting bridge to realize the emission of the excitation pulse.

(2) The receiving module has a built-in signal processing chip to realize the reception of two kinds of response signals, the tunnel nuclear magnetic resonance and the transient electromagnetic. As the core module of the nuclear magnetic resonance and transient electromagnetic integrated detection instrument, the receiving module realizes the reception of nuclear magnetic resonance and transient electromagnetic response signals through a fully digital signal receiving and processing method. The response signal is input to the receiving module of the host through the receiving probe, and the pre-filter amplification of the receiving probe performs preliminary processing on the response signal. After the signal is input into the receiving module, it is further processed through an analog-to-digital conversion input signal processing chip. The signal processing chip processes the NMR and transient electromagnetic response signals separately through the program-controlled digital filter, and finally uploads the processed signal data to the host computer system.

(3) The power module provides reliable working power for the host.

(4) The control module, which controls each module of the host computer to realize the response function.

(5) The communication module realizes the instruction and data interaction between the host computer and the upper computer system.

When working, the nuclear magnetic resonance and transient electromagnetic methods share a set of transmitting and receiving devices. Specifically include the following functions:

(1) Excite the NMR response in water using a square-wave NMR excitation pulse. The nuclear magnetic resonance and transient electromagnetic integrated detection instrument for the advanced prediction of water and mud inrush in tunnels emits bipolar periodic square wave pulses with a frequency of Larmor frequency to excite hydrogen protons in the water body in front of the tunnel face by nuclear magnetic resonance. The host MCU calculates the transmission frequency _{f t} of the transmission pulse according to the measured magnetic induction of the earth's magnetic field, 2π×ft =ωt=γ _p B ₀ . According to the calculated transmission frequency, the host MCU generates a transmission sequence and sends it to the transmission module of the host. The trigger circuit in the transmitting module controls the on and off of the IGBT in the transmitting bridge according to the received transmitting sequence. The pulse emitted by the host transmitting module is a square wave nuclear magnetic resonance excitation pulse. The square wave pulse frequency (fundamental frequency) f _t is the Larmor frequency of hydrogen protons in the water in the survey area, and the pulse form is a bipolar periodic square wave pulse. There are only fundamental wave components and odd harmonic components in the pulse spectrum. The fundamental wave component can excite the hydrogen protons of the body weight of the water and mud inrush disaster in front of the tunnel by nuclear magnetic resonance and receive the nuclear magnetic resonance response signal after the square wave pulse is turned off.

(2) Acquisition and extraction of all-digital tunnel water and mud inrush NMR response signals. After the pulse is turned off, the host MCU sends a signal acquisition command to the receiving module and the receiving probe. The receiving probe is provided with a pre-band-pass active filter amplifier, which can perform preliminary filtering on the collected nuclear magnetic resonance response signal. The collected signal is input to the analog-to-digital conversion circuit of the receiving module to complete the digitization of the signal. Then the analog-to-digital conversion circuit uploads the signal to the DSP chip in the receiving module. After the digitized response signal is input into DSP, the digital quadrature lock-in amplification program compiled in DSP is used as a digital filter to filter the signal to extract the envelope signal of narrow-band NMR response signal. Then the response signal is uploaded to the upper computer system through the communication module for storage and recording. During the receiving process of the entire response signal, all signal processing after the signal is pre-amplified and converted from analog to digital is implemented in the DSP chip through a digital filter algorithm.

(3) Acquisition and extraction of transient electromagnetic response signals for water and mud inrush in full digital tunnels. The transient electromagnetic generator is excited by a bipolar rectangular wave pulse with an adjustable duty cycle. After the forward or reverse excitation pulse is turned off, the host MCU sends a signal acquisition command to the receiving module and the receiving probe. The receiving probe is provided with a pre-band-pass active filter amplifier, which can perform preliminary filtering on the collected nuclear magnetic resonance response signal. The collected signal is input to the analog-to-digital conversion circuit of the receiving module to complete the digitization of the signal. Then the analog-to-digital conversion circuit uploads the signal to the DSP chip in the receiving module. The digital band-pass filter circuit in the DSP chip performs band-pass filter processing on the digitized signal, and then uploads the processed response signal to the host computer system through the communication module for storage and recording. During the receiving process of the entire response signal, all signal processing after the signal is pre-amplified and converted from analog to digital is implemented in the DSP chip through a digital filter algorithm.

In conjunction with accompanying drawing 3, the working principle of a nuclear magnetic resonance and transient electromagnetic integrated detection instrument for advanced prediction of tunnel water and mud inrush is explained as follows.

After the integrated detection instrument is turned on, the host starts the self-test function and uploads the self-test results to the upper computer system for display. If the self-test fails, the upper computer system will generate an alarm and interrupt all instrument operations. After the operator eliminates the fault and the self-test passes, the integrated detection instrument will enter the normal working state. When starting to work, first select the nuclear magnetic resonance or transient electromagnetic measurement method through the host computer software. The working principles of the two measurement methods of nuclear magnetic resonance and transient electromagnetic are respectively described below:

(1) Select the NMR measurement method, and the integrated detection instrument enters the high-frequency working mode. Firstly, the current earth magnetic field parameters are measured by the instrument and the axial direction and true north direction of the transmitting coil are calibrated. The measured parameters of the earth's magnetic field include: the magnetic induction intensity of the earth's magnetic field, the inclination angle of the earth's magnetic field and the declination angle of the earth's magnetic field. The host MCU calculates the transmission frequency _{f t} of the transmission pulse according to the measured magnetic induction of the earth's magnetic field, 2π×ft =ωt=γ _p B ₀ . According to the calculated transmission frequency, the host MCU generates a transmission sequence and sends it to the transmission module of the host. The trigger circuit in the transmitting module controls the on and off of the IGBT in the transmitting bridge according to the received transmitting sequence. The frequency at which the IGBT is turned on and off is the calculated firing frequency f _t . The power supply of the transmitting module comes from the transmitting power supply connected with an external power supply.

The bipolar periodic square wave pulse of the pulsed odd function emitted by the transmitting module. According to the theory of harmonic analysis, the bipolar periodic square wave pulse contains DC components, fundamental waves and higher harmonic components. When the square wave pulse function is an odd function, the frequency spectrum of the pulse only has fundamental wave components and odd harmonic components. And the fundamental frequency is the transmission frequency f _t . Since the fundamental wave frequency is equal to the Larmor frequency of hydrogen protons in water, it can be excited by NMR and the NMR response signal can be received after the square wave pulse is turned off. In Figure 3, the four IGBT tubes Q ₁ ~ Q ₄ are respectively located on the four bridge arms of the bridge circuit, D ₁ ~ D ₄ are freewheeling diodes, and Z _L represents the impedance of the exciting coil.

During pulse transmission, when the square wave pulse is positive, the two tubes Q ₁ and Q ₄ are turned on; when the square wave pulse is negative, the two IGBTs Q ₂ and Q ₃ are turned on. In order to prevent the short circuit of the power supply, the reverse circuit in the transmitter module ensures that the two tubes on the two bridge arms on the same side will not conduct at the same time. During the commutation of the square wave pulse, the freewheeling diodes D ₁ ~ D ₄ ensure that the current on the load is continuous, and the overvoltage caused by the sudden change of the inductive load current will break down the device. The clamping circuit composed of two anti-parallel diodes D ₅ and D ₆ will automatically shut down when the load terminal voltage is lower than its conduction voltage drop, and clamp the output terminal voltage to zero; ensure the rapid shutdown of the emission current pulse. The excitation pulse duration is controlled according to the desired depth of exploration.

After the pulse is turned off, the host MCU sends a signal acquisition command to the receiving module and the receiving probe. The receiving probe is provided with a pre-band-pass active filter amplifier, which can perform preliminary filtering on the collected nuclear magnetic resonance response signal. The collected signal is input to the analog-to-digital conversion circuit of the receiving module to complete the digitization of the signal. Then the analog-to-digital conversion circuit uploads the signal to the DSP chip in the receiving module. The DSP chip is a dedicated signal processing chip in the receiving module. Its advantage is that it handles a large number of floating-point operations, which is very suitable for signal processing. After the digitized response signal is input into DSP, the digital quadrature lock-in amplification program compiled in DSP is used as a digital filter to filter the signal to extract the envelope signal of narrow-band NMR response signal. Then the response signal is uploaded to the upper computer system through the communication module for storage and recording. Acquisitions are performed multiple times according to the number of superpositions set in the launch command, and the collection of excitation and response signals of nuclear magnetic resonance is finally completed by superposition.

(2) Select the transient electromagnetic measurement method, and the integrated detection instrument enters the low-frequency working mode. The transmission parameters such as the frequency, duty cycle, superposition times, and transmission current of the rectangular wave pulse to be transmitted are set through the host computer software. After the transmission parameters are set, they are sent to the host through serial communication.

The host's communication module receives the transmit parameters and sends them to the host MCU. The host MCU generates a transmit sequence and sends it to the host's transmit module. The trigger circuit in the transmitting module controls the on and off of the IGBT in the transmitting bridge according to the received transmitting sequence.

When the bipolar rectangular wave pulse is positive, the two tubes Q ₁ and Q ₄ are turned on; when the bipolar rectangular wave pulse is negative, the two IGBTs Q ₂ and Q ₃ are turned on. Different from the working mode of nuclear magnetic resonance, after the forward or direction excitation pulse is turned off, the host MCU sends a signal acquisition command to the receiving module and the receiving probe. The receiving probe is provided with a pre-band-pass active filter amplifier, which can perform preliminary filtering on the collected nuclear magnetic resonance response signal. The collected signal is input to the analog-to-digital conversion circuit of the receiving module to complete the digitization of the signal.

Then the analog-to-digital conversion circuit uploads the signal to the DSP chip in the receiving module. The digital band-pass filter circuit in the DSP chip performs band-pass filter processing on the digitized signal, and then uploads the processed response signal to the host computer system through the communication module for storage and recording. Acquisitions are performed multiple times according to the number of superpositions set in the launch command, and the collection of excitation and response signals of nuclear magnetic resonance is finally completed by superposition.

Figure 2 shows the transmitting coil bracket of a nuclear magnetic resonance and transient electromagnetic integrated detection instrument for advanced prediction of tunnel water and mud inrush. The outer contour of the whole transmitting coil support is square, the middle part of the support is in the form of a rice-shaped structure, and the nine probe fixing holes 4 are evenly distributed on the rice-shaped support. The coil support is assembled from a support rod and connection head made of thermoplastic thermoplastic.

Coil support rods are available in small and large sizes.

The outer length of the assembled small coil support is 600 cm, the center-to-center spacing of each probe fixing hole 4 is 150 cm, and the diameter adjustment range of the probe fixing holes 4 is 10-20 cm. The outer profile of the bracket is assembled by 8 bracket rods with a side length of 290 cm and a diameter of 5 cm. There are threads on both sides of the bracket rod for connection and fixing, and the length of the threads is 5cm. The internal support bar 8 of the rice font is 420cm long by eight, and the support bar of 5cm in diameter is assembled. A probe fixing hole 4 is designed in the middle of each rice-shaped support, and a fixing bolt 5 is respectively arranged on the left and right sides of the fixing hole. The diameter of the fixing hole can be adjusted by turning the fixing bolt 5 so as to fix the receiving probe in the probe fixing hole 4 . The inner side of the probe fixing hole 4 is provided with a sponge pad coated with rubber leather to increase the friction and the flexibility of adjustment. There are threads on both sides of the bracket rod for connection and fixing, and the length of the threads is 4cm.

The outer length of the assembled large coil support is 1200 cm, the center-to-center spacing of the probe fixing holes 4 is 300 cm, and the diameter adjustment range of the probe fixing holes 4 is 10-20 cm. The outer profile of the bracket is assembled by 8 bracket rods with a side length of 590 cm and a diameter of 5 cm. There are threads on both sides of the bracket rod for connection and fixing, and the length of the threads is 5cm. The rice-shaped internal bracket is assembled from 8 bracket rods with a length of 840cm and a diameter of 5cm. A probe fixing hole 4 is designed in the middle of each rice-shaped support, and a fixing bolt 5 is respectively arranged on the left and right sides of the fixing hole. The diameter of the fixing hole can be adjusted by turning the fixing bolt 5 so as to fix the receiving probe in the probe fixing hole 4 . The inner side of the probe fixing hole 4 is provided with a sponge pad coated with rubber leather to increase the friction and the flexibility of adjustment. There are threads on both sides of the bracket rod for connection and fixing, and the length of the threads is 5cm.

The connecting head of the coil support rod has three structures: A, B, and C. The A-type bracket connector 1 is used to connect the four vertices of the square coil bracket, and the B-type and C-type bracket connectors 3 are used to connect the Pozi-shaped bracket. Threads are engraved in the connector head to facilitate the assembly of the bracket rod. The three connectors of the A-type bracket connector 1 are distributed in a "claw" shape, and the connection cross-section is a square with a side length of 8 cm. The three connectors of the B-type bracket connector 2 are distributed in a "T" shape, and the cross-section of the connectors is a square with a side length of 8 cm. The C-shaped bracket connector 3 is used as the connection of the bracket bar and as the fixing hole of the center probe. There are two fixing bolts 5 for fixing the receiving probe on both sides of the connecting head, and are used for adjusting the diameter of the fixing hole 4 of the central probe. The inner side of the probe fixing hole 4 is provided with a sponge pad coated with rubber leather to increase the friction and the flexibility of adjustment.

When using nuclear magnetic resonance detection or transient electromagnetic method for advanced forecasting, there are two methods of center point reception and array reception to choose from. Before probing, assemble the transmitter coil bracket according to Figure 2. When the working mode of center point reception is adopted, the probe is fixed on the center probe fixing hole 4 to start detection. When the working mode of array reception is adopted, the receiving probe array is fixed on the corresponding probe fixing hole 4 to start detection.

Although the specific implementation of the present invention has been described above in conjunction with the accompanying drawings, it does not limit the protection scope of the present invention. Those skilled in the art should understand that on the basis of the technical solution of the present invention, those skilled in the art do not need to pay creative work Various modifications or variations that can be made are still within the protection scope of the present invention.

Claims (10)

1. nuclear magnetic resonance, NMR and a transient electromagnetic integrative detection instrument, is characterized in that: include that main frame, transmitting coil, reception are visited Head and master system, main frame includes exporting nuclear magnetic resonance, NMR excitation pulse and the transmitter module of transient electromagnetic excitation pulse, adopts Collection nuclear magnetic resonance, NMR and transient electromagnetic two kinds respond the receiver module of signal, it is achieved between master system and host computer control module Instruction and the communication module of data interaction, control receiver module, transmitter module and the control module of communication module, and supply The power module of electricity；

Described transmitter module provides pulse output to transmitting coil, before the signal of receiving transducer collection is carried out by described receiver module Put filter amplifying processing, and the signal after processing is transferred to control module, it is achieved nuclear magnetic resonance, NMR and transient electromagnetic excitation pulse Launch with response signal reception.

2. a kind of nuclear magnetic resonance, NMR as claimed in claim 1 and transient electromagnetic integrative detection instrument, is characterized in that: described transmitting Coil includes coil brace and launches wire, and coil brace is provided with transmitting coil, and transmitter module receives the transmitting of host computer Order, controls transmitting coil and launches transient electromagnetic excitation pulse and nuclear magnetic resonance, NMR excitation pulse.

3. a kind of nuclear magnetic resonance, NMR as claimed in claim 1 and transient electromagnetic integrative detection instrument, is characterized in that: described coil Bracket outer profile is square, and internal stent is rice font structure, support is provided with nine for fixed reception probe Probe fixing hole, probe fixing hole is evenly distributed on meter font structure support, it is possible to carry out Multi probe array reception.

4. a kind of nuclear magnetic resonance, NMR as claimed in claim 1 and transient electromagnetic integrative detection instrument, is characterized in that: launched Nuclear magnetic resonance, NMR excitation pulse is the bipolarity cycle square wave pulse under Larmor frequency；The transient electromagnetic excitation pulse launched is Dutycycle adjustable bipolarity Square wave pulses.

5. a kind of nuclear magnetic resonance, NMR as claimed in claim 1 and transient electromagnetic integrative detection instrument, is characterized in that: described transmitting It is provided with sectionalizing joint on wire, is adjusted flexibly by the number of turn changing the length transmitting coil launching wire.

6. a kind of nuclear magnetic resonance, NMR as claimed in claim 1 and transient electromagnetic integrative detection instrument, is characterized in that: described main frame Control module include main frame MCU, clock circuit and self-checking circuit, wherein, described clock circuit is that main frame MCU provides work Required clock frequency, self-checking circuit realizes the startup self-detection of system, and the result of self-inspection is uploaded to host computer.

7. a method of work based on instrument as according to any one of claim 1-6, is characterized in that: comprise the following steps:

(1) square wave nuclear magnetic resonance, NMR excitation pulse is used to excite the NMR response in water: according to the earth's magnetic field magnetic induction measured The exomonental tranmitting frequency of Strength co-mputation, uses square wave nuclear magnetic resonance, NMR excitation pulse to excite the NMR response in water, sends out The circuit that triggers penetrated in module controls conducting and the shutoff of IGBT in transmitting bridge according to received transmitting sequence；

(2) tunnel gushing water is dashed forward mud NMR response signals collecting and extraction: to receiver module in control module after pulse-off Send signals collecting order with receiving transducer, the NMR response signal gathered tentatively is filtered, gather signal defeated The analog to digital conversion circuit entered to receiver module completes the digitized of signal；

(3) tunnel gushing water is dashed forward mud Transient electromagnetic response signals collecting and extraction: it is adjustable bipolar that transient electromagnetic sends out employing dutycycle Property Square wave pulses excite, excitation pulse forward or backwards is closed and is had no progeny, and control module sends letter to receiver module and receiving transducer Number acquisition, is filtered the NMR response signal gathered, processes.

8. method of work as claimed in claim 7, is characterized in that: in described step (1), and tranmitting frequency is Larmor frequency Bipolarity cycle square wave pulse carries out nuclear magnetic resonance, NMR to the Hydrogen Proton in tunnel tunnel face front water body and excites；

Control module generates a transmitting sequence according to the tranmitting frequency calculated and sends it to transmitter module, transmitter module In the circuit that triggers control conducting and the shutoff of IGBT in transmitting bridge according to received transmitting sequence.

9. method of work as claimed in claim 7, is characterized in that: in described step (1), square-wave pulse frequency Shi Ce district Nei Shui The Larmor frequency of middle Hydrogen Proton, pulse mode is ambipolar cycle square wave pulse, and the frequency spectrum of pulse only exists fundametal compoment With odd harmonic component.

10. method of work as claimed in claim 7, is characterized in that: in described step (2), signal is filtered by control module Ripple processes the envelope signal of the NMR response signal extracting arrowband, and response signal is uploaded to host computer by communication module System stores and record.