CN112415617A

CN112415617A - Circular electrode powered underground abnormal body detection device

Info

Publication number: CN112415617A
Application number: CN201910778829.7A
Authority: CN
Inventors: 沈建国; 锡振强
Original assignee: Tianjin University Marine Technology Research Institute
Current assignee: Tianjin University Marine Technology Research Institute
Priority date: 2019-08-22
Filing date: 2019-08-22
Publication date: 2021-02-26

Abstract

An underground abnormal body detection device powered by a circular electrode mainly comprises a power supply system, a voltage acquisition system, an upper computer control system and a data processing system, wherein the device adopts the circular power supply electrode, so that the contact between the power supply electrode and the ground can be greatly increased, the distribution of an electric field can be more regular, and the distribution of the electric field can be clearly seen; two power supply modes are adopted, if only the abnormal body is needed to be detected, only direct current power supply can be adopted, the approximate position of the abnormal body can be found out according to the electric field distribution in the stable state, if the depth of the abnormal body, the specific size and the specific plane position of the abnormal body need to be known, a step signal needs to be introduced, comprehensive analysis is carried out according to a direct current field and a field generated by the step signal, and the specific information of the abnormal body is accurately calculated.

Description

Circular electrode powered underground abnormal body detection device

Technical Field

The invention belongs to the technical field of special instruments for detecting and evaluating abnormal bodies before building construction, and particularly relates to an underground abnormal body detection device powered by a circular electrode.

Background

The device is an electrical prospecting method which utilizes a resistivity method to perform abnormal body exploration, wherein the resistivity method is based on different electrical conductivities of components in a stratum, and further solves a series of geological problems by observing and analyzing the rule of electric field distribution in the artificially established stratum. Can be used for detecting a goaf in an oil reservoir, measuring the distribution of underground water and the fault of a building foundation. Dam leakage detection, underground water finding and geological detection before tunnel excavation are carried out at home and abroad by using a resistivity method, but the existing resistivity method is not sensitive enough to small abnormal bodies, data analysis is relatively complex, potential resistivity is adopted to replace real resistivity, great errors exist, the resistivity of a geologic body cannot be accurately reflected, and the measurement result is greatly interfered by surface conditions and climatic factors. The device utilizes the circular electrode to supply power, can generate a more standard electric field, has strong anti-interference capability, more sensitive reaction to an abnormal body, high calculation speed and accurate determination of the position of the abnormal body.

Disclosure of Invention

Aiming at the defects in the prior art, the underground abnormal body detection device powered by the circular electrode adopts the circular power supply system, so that the distribution of an electric field is more regular, the position of the abnormal body can be more clearly found, and the lithology and underground water distribution condition of the ground can be further analyzed.

An underground abnormal body detection device powered by a circular electrode mainly comprises four subsystems: the device comprises a power supply system, a voltage acquisition system, an upper computer control system and a data processing system, wherein a schematic diagram of the system is shown in figure 1.

The power supply system mainly comprises a rod-shaped electrode, a circular electrode and a power supply, wherein the shape of the circular electrode is shown in figure 2, the circular electrode is made by wrapping a single-core copper wire into a large circle after being peeled, the power supply can supply power to the electrode by using a stable direct current source and also can supply power to the electrode by using a transmitting circuit board, a step signal generated by a transmitting circuit can reflect more stratum information, and the circular electrode and the rod-shaped electrode can be used as a positive electrode or a negative electrode.

The voltage acquisition system is composed of array electrodes, a lead and an acquisition circuit board, wherein the array electrodes are arranged in the area where the circular power supply electrodes are located, the array electrodes are numbered from left to right and from top to bottom in sequence, one end of each array electrode is connected to a p port of the acquisition circuit board through the lead, all n ports of the acquisition circuit board are jumped together through jumper caps, and the negative electrode of each power supply electrode is connected to the n ports of the acquisition circuit board through the lead. The acquisition circuit board adopts an ads1274 chip, 24-bit acquisition precision is realized, the error is in microampere level, the sampling frequency adopted during alternating current power supply is 1000Hz or 4000Hz, the sampling frequency is 100Hz during direct current power supply, and 1600 moments of data are acquired each time.

The upper computer control system is mainly used for sending an acquisition instruction and receiving acquired voltage, the selection of time interval, acquisition times and serial ports of each acquisition can be selected on an upper computer interface, an acquisition circuit board starts to acquire 1600 data after receiving the instruction, then the acquired voltage information is transmitted to the upper computer through a usb-to-serial port data line to complete one acquisition, and then the next acquisition instruction is waited; meanwhile, the upper computer simply draws the change trend of the voltage values of all the paths along with time, and respectively stores the voltage values acquired by different paths into a txt file to prepare for further processing.

The data processing system is mainly used for processing the voltage value received by the upper computer control system, and the data volume is too large, so that special mapping software matlab is needed to process the data, wherein the data processing system mainly comprises the steps of calculating the average value of 1600 numbers received by different electrodes, forming a matrix by potential values at different positions, drawing contour graphs at different times by the matlab, finding out the position of an abnormal body according to contour line distribution abnormal points, and further analyzing the data with changed points to find out more accurate information of the abnormal body.

The circular power supply electrode is adopted, so that the contact between the power supply electrode and the ground can be greatly increased, the distribution of an electric field can be more regular, and the distribution of the electric field can be clearly seen; two power supply modes are adopted, if only the abnormal body is needed to be detected, only direct current power supply can be adopted, the approximate position of the abnormal body can be found out according to the electric field distribution in the stable state, if the depth of the abnormal body, the specific size and the specific plane position of the abnormal body need to be known, a step signal needs to be introduced, comprehensive analysis is carried out according to a direct current field and a field generated by the step signal, and the specific information of the abnormal body is accurately calculated.

Drawings

FIG. 1 is a schematic diagram of the present invention;

FIG. 2 is a layout of supply electrodes and array electrodes;

fig. 3 is a contour plot of the difference between an abnormal body and an abnormal body.

Detailed Description

The invention is further described in the following with reference to the figures and specific data processing examples, preferred embodiments, but the scope of protection of the invention is not limited thereto.

An underground abnormal body detection device powered by a circular electrode comprises the following measurement steps:

the method comprises the following steps: the arrangement of the power supply electrode is characterized in that the circular electrode is buried in soil, the rod-shaped electrode is inserted into the soil at the circle center of the circular electrode, a small amount of water can be poured to reduce the contact resistance between the electrode and the soil, and the rod-shaped electrode and the circular electrode are connected with the positive pole or the negative pole of the power supply.

Step two: the array electrode arrangement, here for example 25 array electrodes, is a 5 x 5 square array arrangement, where 25 array electrodes are placed in a circular electrode, numbered in array order, and buried in the soil.

Step three: the 25 paths of signals are connected to the acquisition circuit board through the conducting wires, the 25 paths of signals are sequentially connected to the pins P1-P25 of the acquisition circuit board, and the pins N1-N25 of the acquisition circuit board are in short circuit connection with the pins N, and are connected with the negative electrode of the power supply electrode.

Step four: the method comprises the following steps of switching on a power supply, transmitting a collection signal to a collection board through an upper computer, setting a port of the upper computer, setting the interval time of collection, collecting times, starting upper computer software, continuously collecting the voltage of 1600 time points after the collection board receives the collection signal transmitted by the upper computer, wherein the time interval of each time is 1ms, the upper computer can average 1600 points collected every time, and sequentially storing 25 paths of signals into a txt file, needing to collect data for multiple times, reducing the error of an experiment, and simultaneously storing the data of 1600 time points collected every time into a txt file for further processing.

Step five: the collected voltage values are processed, MATLAB is used for processing the collected voltage values, a contour map of the voltage values collected by 25 paths of voltages is drawn by MATLAB, the position of the abnormal body is found according to the contour map, the contour map of the device in the uniform conductor can be known, the collected data and the voltage values in the uniform conductor can be subtracted, then contour lines are drawn, and the position of the abnormal voltage can be more clearly reflected as shown in figure 3.

Claims

1. The utility model provides an underground anomaly detection device of circular electrode power supply which characterized in that: the system mainly comprises four subsystems: the device comprises a power supply system, a voltage acquisition system, an upper computer control system and a data processing system;

the power supply system mainly comprises a rod-shaped electrode, a circular electrode and a power supply, wherein the circular electrode is made by wrapping a single-core copper wire into a large circle after being peeled, the power supply can supply power to the electrode by using a stable direct current source and also can supply power to the electrode by using a transmitting circuit board, a step signal generated by the transmitting circuit can reflect more stratum information, and the circular electrode and the rod-shaped electrode can be used as a positive electrode or a negative electrode;

the voltage acquisition system is composed of array electrodes, a lead and an acquisition circuit board, wherein the array electrodes are arranged in the area where the circular power supply electrodes are located, the array electrodes are numbered from left to right and from top to bottom in sequence, one end of each array electrode is connected to a p port of the acquisition circuit board through the lead, all n ports of the acquisition circuit board are jumped together through jumper caps, and the negative electrode of each power supply electrode is connected to the n ports of the acquisition circuit board through the lead; an ads1274 chip is adopted by the acquisition circuit board, the acquisition precision of 24 bits is realized, the error is in microampere level, the sampling frequency adopted during alternating current power supply is 1000Hz or 4000Hz, the sampling frequency is 100Hz during direct current power supply, and 1600 moments of data are acquired each time;

the upper computer control system is mainly used for sending an acquisition instruction and receiving acquired voltage, the selection of time interval, acquisition times and serial ports of each acquisition can be selected on an upper computer interface, an acquisition circuit board starts to acquire 1600 data after receiving the instruction, then the acquired voltage information is transmitted to the upper computer through a usb-to-serial port data line to complete one acquisition, and then the next acquisition instruction is waited; meanwhile, the upper computer simply draws the change trend of the voltage values of all paths along with time, and respectively stores the voltage values acquired by different paths into a txt file to prepare for further processing;

the data processing system is mainly used for processing voltage values received by the upper computer control system and processing data by using special mapping software matlab, wherein the average value of 1600 numbers received by different electrodes is obtained, potential values at different positions form a matrix, contour maps at different times are drawn by the matlab, the positions of abnormal bodies are found out according to contour line distribution abnormal points, and the data at the changed points are further analyzed to find out more accurate information of the abnormal bodies.