Method and equipment for continuous detection of variations in the nature or condition of the rocks surrounding a tunnelling machine by an electrical method

摘要

The invention relates to a method and equipment enabling the conductivity of the soil in advance of and around a tunnelling machine to be determined. It uses a generator 5 sending an alternating current between the tunnelling machine 1a and 1b and a remote electrode 6, a voltmeter 7 measuring the voltage between the tunnelling machine and an electrode 8, together with equipment measuring the currents I1, I2, ..., In emitted by different sections of the tunnelling machine. From these parameters, a computer determines the apparent conductivities of the medium in different directions around the tunnelling machine. An examination of these conductivities permits the remote and continuous detection, during the drilling of a tunnel, of changes or degradations in the rock such as faulted zones or potential sources of an inrush of water. <IMAGE>