Strain and acoustic wave testing device and method for high-temperature rock sample

Abstract

A strain and acoustic wave testing device includes an acoustic wave transmitting terminal, an upper pressure-bearing shaft, corundum ejector pins, an upper displacement slide, a lower displacement slide, a heat insulation shell, a carbon fiber sleeve, a rock sample, a lower pressure-bearing shaft, an acoustic wave receiving terminal, a lower copper electrode, pearl powder, a temperature sensor, a transformer, a temperature-acoustic wave control box, an oscilloscope, an upper copper electrode, and a data collection and processing system.

Claims

1. A strain and acoustic wave testing device for a high temperature rock sample, comprising: an upper pressure-bearing head, an acoustic wave transmitting terminal, an upper pressure-bearing shaft, corundum ejector pins, an upper displacement slide, an upper fixed foot block, a lower fixed foot block, a lower displacement slide, a heat insulation shell, a carbon fiber sleeve, a rock sample, a lower pressure-bearing shaft, a lower pressure-bearing head, an acoustic wave receiving terminal, a lower copper electrode, pearl powder, a temperature sensor, a transformer, a temperature-acoustic wave control box, an oscilloscope, an upper copper electrode, and a data collection and processing system, wherein the carbon fiber sleeve wraps the rock sample and is fixed inside the heat insulation shell through two pairs of upper and lower corundum ejector pins; a gap between the carbon fiber sleeve and the heat insulation shell is filled with perlite powder; the upper corundum ejector pins are used to fix the upper displacement slide through the upper fixed foot block, and the lower corundum ejector pins are used to fix the lower displacement slide through the lower fixed foot block; the upper displacement slide and the lower displacement slide are connected to the data collection and processing system respectively; an upper end of the rock sample is connected to the acoustic wave transmitting terminal and the upper pressure-bearing head through the upper pressure-bearing shaft, and a lower end of the rock sample is connected to the acoustic wave receiving terminal and the lower pressure-bearing head through the lower pressure-bearing shaft; the upper copper electrode and the lower copper electrode are mounted on the upper pressure-bearing shaft and the lower pressure-bearing shaft respectively and are connected to the transformer respectively; a middle end of the rock sample is connected to the temperature sensor, the transformer and the temperature-acoustic wave control box; the temperature-acoustic wave control box is connected to the oscilloscope, the acoustic wave transmitting terminal and the acoustic wave receiving terminal respectively; and the carbon fiber sleeve, the temperature sensor, the oscilloscope and the temperature-acoustic wave control box are connected to the data collection and processing system respectively.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 is a schematic structural diagram of a strain and acoustic wave testing device of a high temperature rock sample.

(2) In drawing, reference symbols represent the following components: 1upper pressure-bearing head; 2acoustic wave transmitting terminal; 3upper pressure-bearing shaft; 4corundum ejector pin; 5upper displacement slide; 6upper fixed foot block; 7lower fixed foot block; 8lower displacement slide; 9heat insulation shell; 10carbon fiber sleeve; 11rock sample; 12lower pressure-bearing shaft; 13lower pressure-bearing head; 14acoustic wave receiving terminal; 15lower copper electrode; 16pearl powder; 16temperature sensor; 18transformer; 19temperature-acoustic wave control box; 20oscilloscope; 21upper copper electrode; 22data collection and processing system.

DETAILED DESCRIPTION OF THE EMBODIMENTS

(3) The present invention will be further described below in conjunction with the accompanying drawings.

(4) Refer to FIG. 1.

(5) A strain and acoustic wave testing device for a high temperature rock sample mainly comprises an upper pressure-bearing head 1, an acoustic wave transmitting terminal 2, an upper pressure-bearing shaft 3, corundum ejector pins 4, an upper displacement slide 5, an upper fixed foot block 6, a lower fixed foot block 7, a lower displacement slide 8, a heat insulation shell 9, a carbon fiber sleeve 10, a rock sample 11, a lower pressure-bearing shaft 12, a lower pressure-bearing head 13, an acoustic wave receiving terminal 14, a lower copper electrode 15, pearl powder 16, a temperature sensor 17, a transformer 18, a temperature-acoustic wave control box 19, an oscilloscope 20, an upper copper electrode 21, and a data collection and processing system 22.

(6) The carbon fiber sleeve 10 wraps the rock sample 11 and is fixed inside the heat insulation shell 9 through two pairs of upper and lower corundum ejector pins 4; a gap between the carbon fiber sleeve and the heat insulation shell is filled with perlite powder 16; the upper corundum ejector pins are used to fix the upper displacement slide 5 through the upper fixed foot block 6, and the lower corundum ejector pins are used to fix the lower displacement slide 8 through the lower fixed foot block 7; the upper displacement slide and the lower displacement slide are connected to the data collection and processing system 22 respectively.

(7) The upper end of the rock sample is connected to the acoustic wave transmitting terminal 2 and the upper pressure-bearing head 1 through the upper pressure-bearing shaft 3, and the lower end of the rock sample is connected to the acoustic wave receiving terminal 14 and the lower pressure-bearing head 13 through the lower pressure-bearing shaft 12; the upper copper electrode 21 and the lower copper electrode 15 are mounted on the upper pressure-bearing shaft and the lower pressure-bearing shaft respectively and are connected to the transformer 18 respectively; the middle end of the rock sample is connected to the temperature sensor 17, the transformer 18 and the temperature-acoustic wave control box 19; the temperature-acoustic wave control box is connected to the oscilloscope 20, the acoustic wave transmitting terminal 2 and the acoustic wave receiving terminal 14 respectively.

(8) The carbon fiber sleeve 10, the temperature sensor 17, the oscilloscope 20 and the temperature-acoustic wave control box 19 is connected to the data collection and processing system 22 respectively.

(9) A method for performing a strain and acoustic wave test by using the above-mentioned device sequentially comprises the following steps:

(10) (1) mounting the device on a uniaxial mechanical tester stroke;

(11) (2) regulating the transformer by the temperature-acoustic wave control box to emit current, heating the carbon fiber sleeve and further the rock sample in the carbon fiber sleeve through the upper copper electrode and the lower copper electrode, monitoring the temperature of the carbon fiber sleeve by the temperature sensor in real time, and maintaining the rock sample in the carbon fiber sleeve at a set temperature through the data collection and processing system, and keeping a constant temperature for a period of time after the rock sample reaches the set temperature, thereby ensuring that the rock sample is heated uniformly;

(12) (3) turning on a uniaxial mechanical tester to perform a compression test;

(13) (4) acquiring a difference between the upper displacement slide and the lower displacement slide as an axial strain value of the rock sample in a high-temperature compression process since the corundum ejector pins move axially along with the rock sample in an axial strain process of the rock sample under compression;

(14) (5) transmitting acoustic waves from the acoustic wave transmitting terminal by using the temperature-acoustic wave control box, receiving the acoustic waves by the acoustic wave receiving terminal after the waves pass through the rock sample, and displaying a waveform diagram of the rock sample during high-temperature uniaxial compression process in the oscilloscope to obtain an acoustic wave temporal difference of the rock sample in the high-temperature compression process;

(15) (6) storing various data in the data collection and processing system, and calculating the mechanical parameters of rock, such as compressive strength, Poisson's ratio, and elastic modulus; and

(16) (7) at the end of the experiment, a power source is turned off, and after the device is cooled to room temperature, the rock sample is replaced for the next round of experiments.