TEST DEVICE FOR RESEARCHING PROPAGATION CHARACTERISTIC OF ELASTIC LONGITUDINAL WAVES IN JOINT ROCK MASS

摘要

A test device for researching the propagation characteristic of elastic longitudinal waves in a joint rock mass, the test device comprising three parts, i.e. a launching system (3), a loading system, and a measurement system. A pipe of a launching cavity (6) is made of a high-strength insulating material, and a bullet (5) consists of an armature and a metallic bullet body. The launching system (3) uses magnetic waves generated by an alternating current to drive the bullets (5), and the initial speed of the bullets (5) can vary by changing a discharge voltage, thereby obtaining the propagation characteristic of elastic longitudinal waves having different initial wave speeds in the joint rock mass. The propagation characteristic of the elastic longitudinal waves having different initial waveforms is obtained by adjusting the shape of the bullets (5). The measurement system uses a strain gauge (16) to measure the local displacement of a rock, thereby obtaining a change in the wave speed. The measurement system also uses a digital image processing technique. Two kinds of measured data are compared to ensure the accuracy of the test.