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

摘要： 在花岗岩标本测量面上，布设4条夹角互为45°的视电阻率测线，将标本平行长轴方向的4个面加上弹性约束，沿标本长轴方向加压，测量标本视电阻率随轴向应力的变化，实验结果为：1) 岩石视电阻率变化形态显上升-平稳-下降形态，但平稳段不明显，时间很短；2) 视电阻率开始下降时间，比其他受力方式实验结果都早，约提前10%破裂应力。即：平行于轴压方向的测道，在轴向破裂应力的40%左右开始下降；不平行轴压方向的测道，视电现率约在1/3轴向破裂应力开始下降；3) 电阻率从开始下降起，下降速率逐渐增加，但增加得很缓慢，岩石大破裂前，单位轴向应力变化引起的视电阻率变化幅度也不是很大。

关键词: 岩石电阻率, 地电阻率, 电阻率变化机理