应力作用下层状砂岩电阻率的变化特征

THE PROPERTY OF ELECTRIC RESISTIVITY CHANGE OF LAYER SANDSTONE ROCK UNDER STRESS

摘要:

本实验是在室温条件下对兰州河口砂岩进行了单轴加载,在与加载方向平行、垂直和成45°角的方向上观测了电阻率的变化特征。
主要的实验结果是:
(1)垂直层理加载时电阻率ρ_"(平行于加载方向)和ρ_⊥(垂直于加载方向)的变化分为三个阶段:上升-平稳-下降。(2)平行层理加载时电阻率ρ_"和ρ的变化表现出明显的各向异性。不论平行或是垂直层理加栽,在与层理面45°角的方向上的电阻率变化均较小。本文还对上述结果进行了定性解释。由于这种砂岩的放大因子较小(10-10²),所以不适宜做地电台址。

Abstract:

The electric resistivity of Lanzhou Heko layer water saturated sandstone was investigated experimentally under uniaxial load at room temperature and the changes of electrical resistivity was observed at the angles of 0°, 90°, and 45° to loading direction.
Primary experimental results are as follows:(1) when loading direction is vertical to the layer, the changes of electrical resistivity ρ_" (parallel to loading direction) and ρ_⊥ (vertical to loading direction)are divided into three stages:increase-stabilization-decrease; (2) when the loading direction is parallel to the layer, the changes of electrical resistivity ρ_" and ρ_⊥ are characterized by obvious anisotropism. For the abovementirned loading directions, the change of electrical resistivity at an angle of 45° to layer surface whether parallel or perpendicular, is smaller. Then these results are explained qualitatively. Owing to the fact that the amplifier factor of the sandstone is smaller (10-10²), it is not suitable to build the geoelectric station on the sandstone.