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岩体自由场的动应变测量,是在岩体中打一个钻孔,将传感器埋入其中;在动荷载的作用下,岩体发生变形时,传感器应随着岩体产生相应的变形。这样,才能真实地反映岩体的变形。然而,在实际工作中,传感器测出的变形往往很难与岩体真正的变形相一致.原因是在岩体中打了一个钻孔之后,局部破坏了岩体的天然应力场;其次,传感器与岩体为两种不同特征阻抗的介质.当应力波到达不同介质的界面时,将产生折射和反射现象,因此使测量带来一定的误差。对于前一个问题,只要打孔就难避免,但其影
The dynamic strain measurement of rock free field is to drill a hole in the rock body and bury the sensor in it; under the action of the dynamic load, when the rock body is deformed, the sensor should produce corresponding deformation along with the rock body. In this way, it can truly reflect the deformation of the rock mass. However, in actual work, the deformation measured by the sensor is often difficult to be consistent with the actual deformation of the rock mass. The reason is that after drilling a hole in the rock mass, the natural stress field of the rock mass is partially destroyed; secondly, the sensor And the rock mass is a medium with two different characteristic impedances. When the stress wave arrives at the interfaces of different media, refraction and reflection phenomena will occur, thus making the measurement bring certain errors. For the former problem, as long as the hole is difficult to avoid, but its shadow