中国的三种体积式应变仪

VOLUME STRAINMETERS IN CHINA

第一次对外报导了中国的三种体积式应变仪的进展情况。第一种为Sacks——Evertson型钻孔应变仪,文中介绍了中国制造的这种仪器的参数和工作特性,举出了几个震前异常的例子;第二种为“液压型”体积式应变仪。它由一只小型液压差传感器取代了原Sachs仪器中的核心元件:位移传感器、波纹管和小孔滤波装置改装而成。这种改进一方面使仪器的长度缩短,便于制作、运输和下井安装,另一方面提高了仪器的高频特性和抗震、抗过载的能力;第三种为刚研制成功的全固体化动态应变计,利用大型PZT压电陶瓷嵌入不锈钢筒中,能获得足够高的动态应变灵敏度和较宽的频带,能在较深的钻孔中工作,使用灵活,对短临前兆的观测及同震应变阶跃、应变地震波、地脉动等现象的观测研究有一定意义。

In this paper, the development of three types of volume strainmeter in China is reported for the first time. One of them is the well - known Sacks - Evertson type borehole strainmeter made in China. We present its performance parameters and characteristics, and show some examples of earthquake precursors which are more or less similar to that observed in Japan. The second one is a hydraulic pressure type volume strainmeter. It uses a differential hydraulic pressure transducer instead of the three elements in Sacks-Evertson's instrument: fine displacement transducer, bellows, and small bore filter. This improvement shortens the length of the strainmeter, facilitates the making, transportation and installation. On the other hand, this improves its high frequency response and the capability of shock resistance, and overload capacity. The working principles and structures are given in the paper. The third type is a solid - state dynamic strainmeter which is being manufactured at present. Large PZT piezoelectric ceramics is embeded in a tube of rustless steel. It has high dynamicstrain sensitivity (for example, 10 ), wider frequency band (10-100 Hz), and it can work indeep borehole also. Besides, it has a very good adaptability (for example, it can be refitted into stressmeter, groundsound meter and water tremor meter, etc.. We hope it can be used for observations of short-term earthquake precursors, co-seismic strain steps, seismic strain waves, and microseisms etc..