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用双剪法对四种岩石的摩擦滑动特征进行了实验研究。研究的岩石有济南辉长岩、点苍山大理岩、周口店石灰岩和小浪底砂岩。实验的正应力为20、40和近60MPa。实验表明辉长岩岩块在上述正应力下均发生粘滑现象。当正应力为20MPa时,粘滑过程中出现位移弱化现象。当正应力为40和52.5MPa时,在粘滑过程中保持稳定的摩擦强度。当正应力为57MPa时,粘滑过程中出现位移强化现象。大理岩和砂岩当正应力为20MPa时发生稳滑,当正应力提高到40MPa时发生粘滑并出现位移弱化现象。石灰岩实验未观察到粘滑现象。辉长岩与大理岩之间的摩擦出现粘滑,位移弱化现象非常显著。摩擦强度除砂岩等于拜尔利(Byerlee)定律的值外,其它资料均低于拜尔利定律的值,在出现位移弱化场合,粘滑发生前的声发射前兆不显著,而出现位移强化的场合,粘滑的声发射前兆非常显著。本文分析了出现位移强化和位移弱化的原因,讨论了摩擦滑动实验研究的意义。
The friction sliding characteristics of four kinds of rocks were experimentally studied by double shear method. The studied rocks include Jinan gabbro, Dangcang marble, Zhoukoudian limestone and Xiaolangdi sandstone. The normal stress of the experiment is 20, 40 and nearly 60 MPa. Experiments show that the gabbro rock blocks are stick-slip under the above normal stress. When the normal stress is 20 MPa, displacement weakens during the stick-slip process. When the normal stress is 40 and 52.5 MPa, stable frictional strength is maintained during stick-slip. When the normal stress is 57 MPa, displacement strengthening occurs in the stick-slip process. Marble and sandstone are stable when the normal stress is 20MPa, and when the normal stress is increased to 40MPa, stick-slip occurs and the displacement weakens. No stick-slip phenomenon was observed in the limestone experiment. The friction between gabbro and marble is sticky and slippery, and the phenomenon of weak displacement is very significant. In addition to the value of sandstone equal to Byerlee’s law, the frictional strength is lower than the value of Bayley’s law. In the presence of weak displacement, the acoustic emission precursor before stick-slip is insignificant, and displacement-enhanced On occasions, sticky-sounding acoustic emission precursors are very significant. This paper analyzes the causes of the displacement enhancement and the weakening of the displacement, and discusses the significance of the friction sliding experimental study.