关键词: 岩石电阻率, 地电阻率, 电阻率变化机理

Abstract: Four arrays of apparent resistivity are arranged at this measuring surface of granite sample symmetrically with symmetrical four-electrode method, and at an angle of 45°between any two adjacent arrays. The elastic constraint is exerted on 4 surfaces for parallel to the longest dimension of the sample. The samples are compressed along the direction parallel to the longest dimension of the cubic, and the variation of apparent resistivity during the whole loading process is observed. The experimental results are the following: 1) the resistivity changing features of rock show rise-smooth-drop, and the smooth segment is very short and unobvious. 2) the time of first drop for the apparent resistivity is earlier than all other loading experimental results, the rupture stress about moves up by 10 per cent. Viz: the apparent resistivity starting drop when axial rupture stress increases about 40 per cent for the array parallel to the axial; the apparent resistivity starting drop when axial rupture stress reaches about one-third for the arrays non-parallel to the axial. 3) the speed of resistivity drop gradually increases since the resistivity starting drop, but increase is quite slow, and the resistivity change amplitude which is caused by the unit axial stress variety is not very large before the rock big rupture.

Key words: electric resistivity of rock, terrestrial resistivity, mechanism of physics for resistivity variation