Experimental Study of Ultrasonic Waves Propagating Through a Rock Mass with a Single Joint and Multiple Parallel Joints
Experimental Study of Ultrasonic Waves Propagating Through a Rock Mass with a Single Joint and Multiple Parallel Joints
复制标题
超声波在单节理和多平行节理岩体中传播的实验研究
DOI：
10.1007/s00603-013-0399-2
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发表时间：
2014-03-01
影响因子：
6.2
通讯作者：
Dong, Wanli
中科院分区：
文献类型：
--
作者：
Huang, Xiaolin;Qi, Shengwen;Dong, Wanli
通过实验研究了超声波在垂直于节理方向的单节理和多平行节理岩体中传播时，透射比（TR）与正应力、节理粗糙度、节理数目和入射波频率的关系。超声波的产生和接收的压电换能器对和记录的超声波探测器。通过液压千斤顶和加载架对试件施加正应力。研究中的节理岩体是由岩块叠加而成。通过在直接锯切形成的平面接头上开槽来产生粗糙接头。在多个平行接头的情况下，当接头数量改变时，试件的总厚度保持不变。实验中分别使用了三对不同频率的P波换能器和一对不同频率的S波换能器，所有换能器都垂直于关节发射信号。结果表明，随着正应力的增大，TR增大，但增大率逐渐减小。当正应力足够高时，即使岩体有许多节理，TR也接近1，这一点尤其明显。此外，试验还表明，波的频率越高，其TR越低，并且这种现象随着正应力的增加而逐渐减少。在S波的响应，TR随关节粗糙度的增加而增加;然而，在P波的响应，TR随关节粗糙度的增加而逐渐减小。对于P波垂直入射的固定厚度岩体中的多条平行节理，TR并不总是随节理数目的增加而减小，对于某一入射波，TR存在一个临界节理间距：当节理间距小于临界值时，TR将随节理间距的减小而增大。实验结果支持基于Cai和Zhao（Int J Rock Mech Min Sci 37（4）：661-682，2000）、Zhao等人（Int J Rock Mech Min Sci 43（5）：776-788，2006 b）和Zhu等人（J Appl Geophys 73：283-288，2011 a）得出的分析结果的类似结论。
Experiments were conducted to study the relationship between the transmission ratio (TR) and normal stress, joint roughness, joint number and frequency of incident waves, respectively, when ultrasonic waves pass across a rock mass with one joint and multiple parallel joints oriented normally. The ultrasonic waves were generated and received by pairs of piezoelectric transducers and recorded by an ultrasonic detector. The specimens were subjected to normal stress by a hydraulic jack and loading frame. The jointed rock mass was produced by superposing rock blocks in the study. Rough joints were produced by grooving notches on the planar joints formed by sawing directly. In the case of multiple parallel joints, the overall thickness of specimens was maintained while the joint number changed. Three pairs of P-wave transducers and one pair of S-wave transducers with different frequencies were, respectively, applied and all transducers emitted signals perpendicular to the joints in the experiment. The results indicate that TR increases with increasing normal stress while the increment rate decreases gradually. This is particularly so when the normal stress is high enough that TR will approximate 1 even if the rock mass has many joints. In addition, the experiments indicate that the higher the wave's frequency, the lower its TR, and this phenomenon is gradually reduced as the normal stress increases. In response to S-waves, TR increases with increase in joint roughness; however, in response to P-waves, TR decreases gradually with increase in joint roughness. For multiple parallel joints in a fixed thickness rock mass with normally incident P-waves, TR does not always decrease with increase in the number of joints, and there is a threshold joint spacing for a certain incident wave: when the joint spacing is smaller than the threshold value, TR will increase with a decrease in joint spacing. The experimental results support similar conclusions based on analytical results drawn by Cai and Zhao (Int J Rock Mech Min Sci 37(4):661-682, 2000), Zhao et al. (Int J Rock Mech Min Sci 43(5):776-788, 2006b) and Zhu et al. (J Appl Geophys 73:283-288, 2011a).