单轴应力作用下两种不同方法研究岩石磁化率变化的结果

本文介绍了对北京——唐山地区八种强磁性岩石标本的压磁实验结果,观察了它们在高压应力下,直至破坏前后的磁化率变化特征。发现磁化率的变化只是其应力值的函数,与体积变化过程、微裂膨胀过程关系甚微。磁化率的压力系数取值范围为——(0.4——3.0)10-3MPa-1。同时,本文还得到了标本中出现破裂后岩石的压磁曲线。 运用铁磁学理论,对上述压磁实验结果作了初步的分析解释。 

THE EXPERIMENTAL RESULTS OF VARIATIONS IN THE SUSCEPTIBILITY OF ROCK SAMPLES UNDER UNIAXIAL STRESS BY TWO DIFFERENT APPROACHES

This paper shows the results of piezomagnetic experiments on eight kinds of strong magnetic rocks collected in the Beijing-Tangshan area of China under uniaxial pressure. The features of variation in magnetic susceptibility with increasing stress until fracture and even after fracture have been observed. It is shown that the variation in magnetic susceptibility is mainly a function of stress but not of strain,volume change,or relaxation. The large volume change marked by strong acoustic emission under a stable stress didn't cause any obvious,excessive change in susceptibility. Thus,this puts a negative factor on the possible dilatancy-magnetic precursor of earthquakes.Comparing the experimental results from two different approaches,this paper shows that the results are quite consistent. Thus it is shown that a simple detector attached to.the surface of the sample will provide a powerful tool in studying the variation in susceptibility. This makes the synchronous measurements of susceptibility,bulk strain,accoustic emission etc. easier.This paper also discusses the two types of piezomagnetic curves and their possible physical meaning.The measured coefficients of piezomagnetic variation versus stress range around -(0.4-3.0)10-3 MPa-1 for the rocks tested.