Detection of underground cracks and thin weak layers using blasting vibration
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摘要: 从爆破震动信号主要来源于爆破区邻近范围内地质结构的自振的观点出发,提出了一种探测地下裂隙和软弱夹层的新技术:把震源布置在裂隙和软弱夹层附近进行爆破,由于介质中裂隙和软弱夹层的存在使得局部结构的刚度减小,直接影响到爆破介质振动的速度幅值和频率,因此可以通过地表接收器接收的振动信号(包括振动速度的幅值和频率)识别出裂隙和软弱夹层的大小和形状等特征.通过无网格的数值算例分别从水平裂隙和斜裂隙的情况下总结规律说明了这种方法的可行性.Abstract: By using the assertion that the propagated wave signal mainly comes from the natural vibration of geophysical structure after blasting, a new technique is proposed for detecting underground large scale cracks and thin weak layers. This technique indicates that the local stiffness decreases, owing to the exist of the cracks or thin weak layers in the medium, which directly effects the vibration velocity and frequency of the medium. The character of cracks or thin weak layers can be detected by the signals (including the vibration velocity and frequency) received on the ground if placing the source of blasting vibration near cracks or thin weak layers. The calculations were performed by a recently developed SPH(smoothed particle hydrodynamics) method and shown the contrast of the blasting vibration signals between the situation when cracks were horizontal and inclined. The results drawn a conclusion and showed the possibility of this method.
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Key words:
- blasting vibration /
- geo-structure /
- natural vibration /
- crack /
- thin weak layer
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