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坎伯恩矿业学院(CSM)等关于干热岩体(HDR)地热能源项目的研究经验清楚地表明:干热岩体热交换的开发在很大程度上取决于天然裂隙网络与原位应力状态的相互影响,为了有效地利用地层深部(>4km)的干热岩体,若采用常规应力测量技术,诸如水力压裂,那是特别困难的。因此,人们对另一种应力测量技术,即声发射(AE)凯塞效应(KE技术,有相当大的兴趣,本文介绍了在英国科恩沃尔一个矿山的Carnmenellis花岗岩中,其深度为840m。用常规的套钻应力解除法和AE凯塞效应方法测量应力的对比情况,尽管套钻与先前在Carnmenellis花岗岩中进行应力测量的结果比较一致,但是套钻与凯塞效应的数据组之间还存在着明显的差异,值得注意的是KE应力值比预期的应力值明显的要低些。这是由于取出的岩芯与进行AE试验之间的时间延迟和KE应力记忆的保留时距较短所致。重要的是:凯塞效应保留时距(KERS)的研究证明了KERS可能与试验岩样的直径有关。较大的直径具有较长的保留时距。尽管KE技术表明它对于深孔原位应力测量很有前途,但是这种技术目前尚未得到公认,因此还不能用它作为常规的方法对深部原位应力提出明确的评价。
Research experience with the Center for Geothermal Energy in Dry and Hot Rock Mass (HDR), such as the CSM, clearly shows that the development of heat exchange in dry-hot rock mass largely depends on the relationship between the natural fracture network and the in-situ stress state , It is particularly difficult to use conventional stress measurement techniques, such as hydraulic fracturing, in order to effectively utilize dry-hot rock masses in the deep (> 4 km) strata. Therefore, there is considerable interest in another stress measurement technique, the Kaiser Effect of Acoustic Emission (KE), which describes a depth of 840 m in the Carnmenellis granite, a mine in Coenvor, England. Contrasting stress measurements with the conventional stress-relief method and the AE Kaiser effect method, which is consistent with the previous stress-mea- surement results in the Carnmenellis granite, Significant differences exist, notably, that the KE stress is significantly lower than the expected stress due to the shorter time between the core removal and AE testing and retention of KE stress memory It is important that the KERS study evidenced that the KERS may be related to the diameter of the test rock specimen and that the larger diameter has a longer retention time.Although the KE technique indicates that it is more effective for deep holes In situ stress measurement is promising, but this technique is not yet well established and therefore it can not be used as a routine method to give a clear assessment of deep in situ stress.