循环加载高应力对大理岩Kaiser效应影响的试验研究

发布时间：2018-09-09 15:58

【摘要】：声发射法(AE)广泛用于地应力测量。当单次加载Kaiser效应不明显时,可采用循环加载方式。通常各循环峰值加载应力大于岩石在地壳中所受最大应力?m,将大于?m的加载应力称为高应力。为研究高应力对岩石Kaiser效应的影响,对取自铜绿山矿的垂直钻孔岩芯进行循环加载试验,根据声发射特征曲线变化趋势及变形率分析法(DRA)地应力测量结果,对比水压致裂法所测地应力量值,确定不同加载阶段Kaiser效应点位置。研究结果表明:当循环加载峰值应力大于?m时,高应力将削弱与?m对应声发射事件的能量,使后续加载循环Kaiser效应不明显,同时会改变岩石之前记忆的应力值,使AE法地应力测量结果产生偏差;多次循环加载可导致岩石内部微结构面的破坏,其产生的大量声发射事件会混淆Kaiser效应点的辨识;因岩石差异性,高应力可能会取代岩石之前所受最大应力,成为岩石记忆的新应力。鉴于此,采用循环加载方式时,首次加载峰值应力A?应不超过?m,同时应使岩石跨过压密阶段进入线弹性阶段。铜绿山矿所取岩样循环加载试验结果表明,A?较合适的取值范围为岩石单轴抗压强度的6%~28%。此外,还给出声发射法和DRA法联合用于地应力测量的合理加载方式。
[Abstract]:Acoustic emission method (AE) is widely used in geostress measurement. When the Kaiser effect of single loading is not obvious, cyclic loading can be adopted. In general, the peak loading stress of each cycle is greater than the maximum stress of rock in the crust, and the loading stress greater than the peak value is called high stress. In order to study the effect of high stress on rock Kaiser effect, cyclic loading tests were carried out on the vertical core from Tonglushan Mine. According to the change trend of acoustic emission characteristic curve and deformation rate analysis method, (DRA) geostress was measured. By comparing the geostress values measured by hydraulic fracturing method, the location of Kaiser effect points at different loading stages was determined. The results show that when the peak stress of cyclic loading is greater than m, the high stress will weaken the energy of acoustical emission event, make the cyclic Kaiser effect of subsequent loading less obvious, and change the stress value of the pre-memory of rock. The results of in-situ stress measurement by AE method are deviated, and repeated cyclic loading can lead to the destruction of the microstructural surface of rock, and a large number of acoustic emission events will confuse the identification of Kaiser effect points, because of the difference of rock, High stress may replace the maximum stress before rock and become the new stress of rock memory. In view of this, the peak stress A? It should not exceed m, and the rock should pass through the compaction stage into the linear elastic stage. The cyclic loading test results of samples taken from Tonglushan Mine indicate that the rock samples collected from Tonglushan Mine have been subjected to cyclic loading. The more suitable value range is 6 / 28 of uniaxial compressive strength of rock. In addition, the reasonable loading mode of acoustic emission method and DRA method for in-situ stress measurement is also given.
【作者单位】：中国地质大学工程学院;大冶有色金属有限责任公司铜绿山铜铁矿;大冶有色金属有限责任公司;
【基金】：湖北省自然科学基金重点项目(2014CFA529) 中国地质大学(武汉)教学实验室开放基金资助项目(SKJ2016083)~~
【分类号】：TU45

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