A method for determining the pasting position of strain gauges in layered rock impact compression bar tests

Abstract

The invention discloses a strain gauge adhesion position determining method in a stratified rock shock pressing rod test. The method comprises the following steps: an ultrasonic wave detector is used for measuring wave velocity of an incident bar and different wave velocities of two kinds of rock stratums that form a stratified rock, thickness of the two kinds of rock stratums that form the stratified rock is measured, transmission time of ultrasonic waves transmitting in the two kinds of rock stratums that form the stratified rock is calculated, a shock pressing rod test system is used for conducting punching operation to obtain a wave form and a half cycle of a stress wave, a half wave length of the stress wave and transmission lengths of the stress wave in the incident bar in the two kinds of rock stratums that form the stratified rock in different time are calculated, and therefore adhesion positions of strain gauges can be determined. The strain gauge adhesion position determining method can be used for determining the adhesion positions of the strain gauges, different stress wave separate wave forms and composite wave forms can be obtained via strain gauges at different positions, and basic data can be provided for calculating characteristics such as dynamic mechanics and the like of different rock stratums of the stratified rock under a dynamic load. The strain gauge adhesion position determining method is advantaged by simple procedures and easy operation.

Description

technical field [0001] The invention relates to a method for determining the sticking position of a strain gauge in a layered rock impact compression bar test. Background technique [0002] In coal mines or sedimentary rocks, there are often layered rock formations. Different rock formations vary in density and strength. The layered rock mass propagates in the form of stress waves in its interior when subjected to impact loads. Stress waves produce reflection and transmission during the propagation of layered rock mass. At the same time, due to differences in the density of different rock layers, different stresses on different rock layers are different, resulting in different failure times and damage forms of each rock layer. Therefore it is necessary to calculate the stresses on different rock formations. To calculate the stress on different rock formations generally requires incident, reflected, and transmitted wave waveforms on both ends of the rock formation. Therefo...

AI Technical Summary

Problems solved by technology

For layered rocks, there are mainly rocks composed of two media. The incident wave enters the layered rock from the incident rod, and is reflected at the interface between the incident rod and the rock, the interface between the two rocks, and the interface between the rock and the transmission rod. Transmission, and then secondary transmission and reflection, resulting in more waveforms. If the position of the strain gauge is the same as in the single uniform medium shock bar test, these waveforms may be combined together, and the source of the waveform cannot be distinguished, resulting in insufficient basic data and Can't calculate stress

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