Acoustic emission testing apparatus with acoustic emission sensors built in true triaxial chamber

Abstract

The invention discloses an acoustic emission testing apparatus with acoustic emission sensors built in a true triaxial chamber. T-shaped cavities are processed in rock sample clamps in three directions of a true triaxial electro-hydraulic servo mutagenesis testing system; the acoustic emission sensors are placed in the T-shaped cavities; a rubber plug located at an end part is used for fixing an acoustic emission signal line; the lead-out signal line is connected with a BNC adapter equipped with a terminal; the BNC adapter is directly connected with an amplifier to form a complete acoustic emission monitoring system; and the tail part of each acoustic emission sensor is fixedly connected with a push rod through a magnet piece, the push rod, a spring pad, a hard spring and minisized screws form a force-transferring mechanism together, and the acoustic emission sensor and a rock sample are allowed to always maintain tight contact in virtue of the mechanism. The acoustic emission testing apparatus is simple in structure and strong in operability; the acoustic emission sensors are repeatedly usable; considerable interference signals produced by external arrangement of the acoustic emission sensors are substantially reduced; and authenticity and reliability of acquired acoustic emission signals are guaranteed.

Description

technical field [0001] The invention relates to an acoustic emission test device based on triaxial loading and unloading, in particular to an acoustic emission test device in which an acoustic emission sensor is built in a true triaxial chamber. Background technique [0002] Deep rocks are in a three-dimensional high-stress state, and the methods for studying the mechanical properties of rocks under multi-dimensional stress state mainly include conventional triaxial experiments (σ 1 >σ 2 = σ 3 ≠0) and true triaxial experiments (σ 1 >σ 2 >σ 3 ≠0). Conventional triaxial experiments ignore the influence of intermediate principal stress on rock mechanical properties, which is not conducive to understanding the rock fracture mechanism under real stress state. To carry out the research on the mechanical properties of rock in three-dimensional stress state, it is necessary to use the true triaxial experimental system. [0003] When the rock material is subjected to ...

AI Technical Summary

Problems solved by technology

In this case, the rock sample holder (hydraulic oil and cylinder wall in conventional triaxial) will cause the propagation distance to increase, which will cause the number and energy of the received AE event to decrease (for conventional triaxial equipment, its shear pulse The wave is because the transmission path conversion occurs because it cannot directly pass through the hydraulic oil in the three-axis chamber of the servo machine)

In addition, due to the influence of laboratory environmental noise, etc., when the acoustic emission sensor is placed on the outer wall of the triaxial, it will also be affected by many noises, especially the interference of electromagnetic signals, so the signal-to-noise ratio of the received signal is relatively low

At present, there is still no report on the research on the monitoring of acoustic emission signals in the true triaxial room and the development of related equipment.

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