Influential factors and optimum survey method of advanced focus detection with DC resistivity in tunnels

The influential factors and optimum survey method of the tunnel for DC resistivity advanced focus detection are studied on the basis of introducing the principle of advanced focus detection brifly.We simulate the geoelectric model on conditions of different sizes of the tunnel, different positions of the side anomalous body, as well as two kinds of methods of focusing observation by the finite element method.The results show that the more the side anomalous body close the tunnel ,the greater influence of abnormal curve.The effect of size of the tunnel on advanced focusing can be ignored.The A-M-A_0 array is superior to the A-M array in suppressing side disturbance.It can reach the best detect effect when the transmitting electrode spacing A_0 A is increased as much as possible in practical work, and the ratio of surveying electrode spacing A_0M to supply electrode interval A_0 A is A0M/A0A=0.6.