Research And Design Of Detectors Of Tunnel Water-bearing Structure

With the rapid propulsion of the Belt and Road Initiative,and the last bond of the national infrastructure construction scale, tunnel engineering is increasing, security problems in the process of tunnel excavation is getting more and more attention. Because the tunnel projects are often constructed in the complex geological environment, so if they’re produced geological disaster just like karst underground water and mud in rush in the process of digging, it will cause a huge loss to contractors, more seriously it will poses a great threat to the safety of the construction personnel, so it’s urgently need to advance geology forecast to detect the water-bearing structure in the tunnel, then ensure the safety of the construction. There are many method of advance geology forecast, in electrical method, induced polarization method is the most suitable method for application in the detection of water-bearing rock structure.Based on this requirement, this paper designs an advanced detector which is based on induced polarization method. First introduces the theory of IP, then introduces the designing scheme on account of IP, design each module respectively according to the function and characteristic of the advanced detector which is installed on TBM, introduction and explanation detailed of hardware modules. Mainly includes constant flow source method, control chip, relay array with the driver module, USB module collection method and power module. Then introduces slave computer software and upper computer software, Common operations includes opening the file from the user perspective, testing grounding resistance, settings system, making orders and starting test, querying history curve and quitting the program. The way of testing is measuring ground resistance by measuring electrode first to observe if the electrode and the rock contact well, then power should be supplied by the constant flow source, there are forward and reverse power supply way that can be chosen by upper computer software, current electrodes can also be chosen by upper computer software, too. After a period of time, signal should be measured by measuring electrode, the data would be formed a voltage divider, isolated, smoothing, and adjusted measuring range across measuring module, and then it would be delivered to upper computer software to handle, save and display. The data that finally be displayed on the upper computer software is the complete curves and half-decline time, then the water content can be figured out by the half-decline time. Among these modules, smoothing module is very important in signal processing, according to the characteristic of the target signal, we choose Butterworth low-pass filter, optimize the signal well, achieve the desired objectives.At last, the device has carried on channel calibration, laboratory test, outdoor model test and field test, the test results are analyzed, The final result shows that the data measured by the instrument can satisfy the goal like high precision, high stability, flexible to use, the validity of the instrument is proved in practice.