深孔空心包体法地应力测量仪及其应用实例

HOLLOW INCLUSION STRAIN GAUGE GEOSTRESS MEASURING INSTRUMENT IN DEEP BOREHOLE AND ITS APPLICATION EXAMPLE

介绍用于深孔地应力测量的深孔空心包体法地应力测量仪的组成结构及辅助工具,并给出该仪器的应用实例。传统的应力解除仪器只适用于浅孔,不适用于深孔。深孔空心包体地应力测量仪将原来井上应变仪、井下空心包体应变计、电子罗盘等集成于一体,制成无电缆微型探头,测量时将微型探头安装到孔内预定位置进行测量。用该仪器在上海市浦东地震监测中心张江观测孔进行实际应用,获得365和385 m深处的三维地应力实测数据,测量结果显示张江观测孔最大主应力近水平,方向为近EW向,最大主应力值为8.5～9.0 MPa,最小主应力近于铅直,大小与上覆岩层压力相近。实测表明深孔空心包体地应力测量仪适用于深孔三维地应力测量。

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.