NATURAL GROUND COLLAPSE MONITOR DEVICE FOR UNDERGROUND DRILLING MACHINE

摘要

PURPOSE: To make it possible to monitor the behavior of the ground to check for its collapse with high accuracy during shielding by selecting consecutively at least three combinations abound power supply electrodes and detection electrodes and determining specific resistance about collapse section and substituting the determined value into an equation so as to calculate the thickness of muddy water. ;CONSTITUTION: There is installed an electrode switch-over unit 13 where at least three different combinations about power supply electrodes and detection electrodes are selected one after another. What is more, a power supply 17 and a voltmeter are consecutively changed over for each combination and connected. The specific resistant value of each selected collapse portion 24 is calculated in a CPU 20. On the other hand, the specific resistance and selection power supply electrode span calculated for each combination are consecutively substituted in an equation which shows the relation between the calculated values of specific resistance and spans between selection power supply electrode ranging from 1 to 8 and true specific resistance in a muddy water section 23 in the collapse portion 24 and true specific resistance in a natural ground 22 on the collapse portion 24 and the thickness of the muddy water, thereby determining at least three equations. The thickness of muddy water is calculated based on the equation.;COPYRIGHT: (C)1994,JPO&Japio