Instrument for exploring fractures and cavernouse formation

[0021] It is composed of host, electrode, power supply and cable, and its characteristics are:

[0022] 1. It also has a distributed electrode transfer switch, which connects several switches to each other into a string through a string cable, see Figure 4 , 5 , Figure 5 The composite cable in is 9 cores, A and B are power supply line groups, M and N are measurement line groups, that is, electrodes, 1 is the inner shielding layer, 2 is the outer shielding layer, and 3 is the data communication twisted wire group. 4 is the switch power supply line group. In order to solve the problem of receiving and automatic address selection of the command signal sent by the instrument host, an interface circuit for transmitting the command is designed. The circuit adopts the serial output mode. The host computer changes the instructions serially through the interface circuit, and then through the output circuit for level elevation, the DATA data stream, CLOCK clock and ENABLE function are formed, and the SCI serial data stream is output to each Electrode switch. The characteristic of this interface circuit is that there is no need to judge the number of each switch box itself, and its position is only determined according to the sequence of arrangement, thus achieving the purpose of automatic location selection. At the same time, the electrical structure of the distributed electrode switch adopts large-scale integrated circuit technology and is processed with chip packaging technology to reduce the volume of a single switch to φ15×110mm. In addition, a special composite cable for anti-interference was developed as a series connection cable for distributed electrodes. In order to solve the problem of serious interference between the high-voltage power supply line, measurement line, digital communication line and power line in the cable, a double-layer shielding is designed in the line, in which the AB power supply line is shielded by aluminum film, and the entire cable is aluminum film Add braided bare wire shielding. The outer skin is made of anti-aging polybutylene chloride material, which has a high degree of insulation. In this way, the cable and the electrode transfer switch are integrated, which is both a cable and a switch, which greatly reduces the weight and volume;

[0023] 2. The said host selects a high-performance industrial computer with large memory and fast data processing as the main processor, and designs a control acquisition interface circuit associated with the parallel port of the computer, so that the computer can output control instructions to the main control through the parallel port The main control board decodes and controls the work of each part of the board. The main control board sends the collected V and I signals to the computer through the interface, and the computer performs calculation, processing, and graphing.

[0024] 3. In order to display the resistivity chromatogram of the geoelectric structure in real time, inversion imaging is a focus of this research. We applied the RES2DINV high-density resistivity data inversion program to effectively solve this problem. It uses the quasi-Newton optimization (Loke and Barker1996) least squares technique, which is more than 10 times faster than the conventional least squares method, and can adjust the damping coefficient and smoothing filter coefficient to meet the needs of different models.

[0025] 4. In order to meet the needs of different detection targets and improve the accuracy and resolution of the measurement work, the instrument has added a high-density dual-frequency IP method. This method solves geological problems by measuring the dispersion rate of the secondary field. To effectively measure the frequency dispersion rate of the secondary field, it is necessary to solve the interference problem between the high-voltage power supply wire and the measurement wire, and improve the anti-interference ability of the instrument. Through the improvement of the instrument circuit and the optimized selection of electronic components, we have improved the measurement accuracy and anti-interference ability of the instrument. The distributed electrode switch and double shielded cable that have been developed have overcome the interference between the lines, so that the instrument can accurately measure To the weak secondary field, high-density dual-frequency IP measurement function can be realized.