金川三矿地应力测量及应力状态特征研究

In-situ stress measurement and study of stress state characteristics of Jinchuan No.3 mine

金川三矿位于金川矿区F17断层以东,是超基性贫矿。随着选矿和冶炼水平的提高,三矿区逐渐进入开采阶段。了解矿山深部的地应力状态可以为巷道开挖和支护设计提供科学依据。为此在三矿1 200 m水平进行了系统的地应力测量,以了解三矿区的地应力状态特征。现场测量采用改进的空芯包体应力解除法,共获得了7个测点的三维应力数据,并绘出了各测点不同法线方向的截面应力椭圆。测量结果表明,在井下约520 m深度,最大主应力量值约为17~21 MPa,属于中等应力水平。最大主应力方向分为NNW^NNE和NE^WE两组,与区域应力场基本吻合,但又表现出新的趋势方向,其原因可能是受三矿区内两条断裂的影响。部分测点最大主应力倾角超过20°,最大达-49°,以水平应力为主的矿区应力场特征发生改变。研究结果对矿山设计及施工具有重要意义。

The Jinchuan No. 3 mine in Gansu province of China, is an ultrabasic lean ore and locates at east of fault F17 of Jinchuan mine area. With the improvement of mineral processing and smelting, exploiting of No. 3 mine is on the way. Understanding of in-situ stress state in deep mine can provide the scientific basis to extract and support roadway. In-situ stress measurement was conducted at 1 200 m level to achieve this goal. A improved hollow inclusion stress relief method was employed to obtain three-dimensional stress data of seven measurement sites, which were used to draw section stress-ellipses at different normal directions of each site. The measurement results indicate that at 520 m below the surface, the values of maximum principal stress are about 17-21 MPa, a medium stress level. The directions of the maximum principal stress are within NNW-NNE and NE-WE, and agree with regional stress field basically, and also show a new trend direction. It is probably two faults in No.3 mine area that pose an influence on the direction of the principal stress. However, some dips of maximum principal stress exceed 20° and the largest one is -49°, which reveals a change of horizontal-stress-orient stress field in Jinchuan mine. The result is of great significance in mine design and construction.