HOLLOW INCLUSION STRAIN GAUGE GEOSTRESS MEASURING INSTRUMENT IN DEEP BOREHOLE AND ITS APPLICATION EXAMPLE
BAI Jinpeng,PENG Hua,MA Xiumin,JIANG Jingjie,LI Zhen
(Key Laboratory of Neotectonic Movement and Geohazards of Ministry of Land and Resources,Institute of Geomechanics,Chinese Academy of Geological Sciences,Beijing 100081,China)
Abstract:The structure of the deep borehole hollow inclusion strain gauge geostress measuring instrument and its assistive tools are described,which were used for deep borehole geostress measurement;and an example is given. Traditional instrument based on stress-releasing theory is only applied to shallow borehole,not applied to deep borehole. The traditional instrument is improved,and a deep borehole hollow inclusion strain gauge geostress measuring instrument is developed. It integrates hollow inclusion strain gauge,strain recording apparatus and electronic compass into a micro-probe,which can be installed at predesigned position in the borehole when measuring the geostress. Geostress data of Zhangjiang observation borehole in Shanghai at the depth of 365 and 385 m underground by using this technology is obtained. The results show that the maximum principal stress direction in surveying area is near EW direction;and the values of the maximum principal stresses are between 8.5 MPa and 9.0 MPa. The minimum principal stress direction is near vertical;and the values of the minimum principal stresses are near equal to the overburden pressure. Measurement results show that deep borehole hollow inclusion strain gauge geostress measuring instrument is suitable for deep hole of 3D geostress measurement.
蔡美峰,乔 兰,李华斌. 地应力测量原理和技术[M]. 北京:科学出版社,1995:1-27.(CAI Meifeng,QIAO Lan,LI Huabin. Rock stress measurement principles and techniques[M]. Beijing:Science Press,1995:1-27.(in Chinese))
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