Rock impact loading-unloading confining pressure test system and usage method therefor

Patent metadata

Field	Value
Publication number	US-11215542-B2
Application number	US-201916652961-A
Country	US
Kind code	B2
Filing date	Feb 28, 2019
Priority date	Dec 24, 2018
Publication date	Jan 4, 2022
Grant date	Jan 4, 2022

Abstract

A rock mechanics test system with impact loading-confining pressure unloading and its usage method. The test system includes bearing frame unit, axial compression loading unit, impact loading unit and confining pressure loading unit. The bearing frame unit includes pedestal, column and cross beam. The column is vertically installed on both sides of the upper surface of the pedestal, and the cross beam is horizontally fixed on the upper part of the column. The axial compression loading unit is fixed at the middle position of the upper surface of the pedestal and is used to exert the axial bottom-up pressure to the sample. The impact loading unit is fixed on the cross beam and is used to exert the axial top-down impact load on the sample.

First claim

What is claimed is:

1. A rock mechanics test system with impact loading-confining pressure unloading comprising:
a bearing frame unit includes pedestal, column and cross beam; the column is vertically installed on both sides of the upper surface of the pedestal, and the cross beam is horizontally fixed on the upper part of the column;
an axial compression loading unit is fixed at the middle position of the upper surface of the pedestal and is used to exert the axial bottom-up pressure to a sample;
an impact loading unit is fixed on the cross beam and is used to exert the axial top-down impact load on the sample;
a confining pressure loading unit is installed between the axial compression loading unit and the impact loading unit, and is used to exert the confining pressure in the horizontal plane to the sample;
wherein,
a confining pressure unloading unit is used to unload the confining pressure of one side wall direction in the horizontal plane of the sample;
a loading control unit is used to control the axial compression loading unit, the impact loading unit and the confining pressure loading unit for loading, respectively;
a monitoring unit is used to monitor the stress, deformation and failure characteristics of the sample during the whole process of loading and unloading;
a data analysis unit is connected to the loading control unit, and is also used to process and analyze the data received from monitoring unit;
wherein the confining pressure loading unit includes a pressure chamber, three confining pressure loading hydro-cylinders, a confining pressure loading oil tank and three first lateral pressure heads, the sample is placed in a pressure chamber; the confining pressure loading oil tank is connected to the confining pressure loading hydro-cylinders; the piston rods of the confining pressure loading hydro-cylinders are connected to the three first lateral pressure heads; the three first lateral pressure heads extend horizontally into the pressure chamber and are contacted to the three side walls of the sample; the confining pressure unloading unit is installed on the fourth side wall outside of the pressure chamber.

2. The rock mechanics test system with impact loading-confining pressure unloading according to claim 1 , wherein the axial compression loading unit includes an axial compression loading hydro-cylinder, an axial compression loading oil tank and a lower pressure head; the axial compression loading hydro-cylinder is fixed to the pedestal; the axial compression loading oil tank is connected to the axial compression loading hydro-cylinder; one end of the lower pressure head is connected to the axial compression loading hydro-cylinder; the other end extends vertically into the confining pressure loading unit, and is in contact with the lower surface of the sample.

3. The rock mechanics test system with impact loading-confining pressure unloading according to claim 1 , wherein the impact loading unit includes an impact loading hydro-cylinder, an impact loading oil tank, an upper pressure head and a pressure bearing column; the impact loading hydro-cylinder is fixedly connected to the cross beam, and the impact loading hydro-cylinder is connected to the impact loading oil tank; one end of the pressure bearing column is connected to the piston rod of the impact loading hydro-cylinder, and the other end is connected to the top of the upper pressure head; the bottom of the upper pressure head is in contact with the upper surface of the sample.

4. The rock mechanics test system with impact loading-confining pressure unloading according to claim 1 , wherein the confining pressure unloading unit includes a second lateral pressure head, a strut, a confining pressure unloading hydro-cylinder, a first pressure sensor and an unloading controller; the second lateral pressure head is installed on the fourth side wall outside of the pressure chamber, and one end of the second lateral pressure head extends horizontally into the pressure chamber and is contacted to the fourth side wall of the sample; the other end of the second lateral pressure head is hinged to one end of the strut, and the other end of the strut is installed with the pulleys; the confining pressure unloading hydro-cylinder is connected to the confining pressure loading oil tank; the piston rod end of the confining pressure unloading hydro-cylinder is installed with the pulley grooves, and the pulleys of the strut cooperate with the pulley grooves; the inside of the pulley grooves are further installed with baffles that can be opened and closed; when the baffles are opened, the pulleys can slide freely along the pulley grooves; when the baffles are closed, the pulleys can be locked in the pulley grooves; a first pressure sensor is installed between the second lateral pressure head and the sample; an unloading controller is connected to the first pressure sensor and the baffles, respectively.

5. The rock mechanics test system with impact loading-confining pressure unloading according to claim 3 , wherein the monitoring unit includes a second pressure sensor, strain gauges, a dynamic strain gauge, a high-speed camera and a signal collector; the second pressure sensor is respectively installed between the pressure bearing column and the upper pressure head, and is also installed between one of the three first lateral pressure heads and the sample; the strain gauges are installed on six outer surfaces of the sample; the dynamic strain gauge is connected to the strain gauges; one end of the signal collector is connected to the second pressure sensor, the dynamic strain gauge and the high-speed camera, and the other end is connected to the data analysis unit; the high-speed camera is installed on the same side of the confining pressure unloading unit and corresponds to the position of the sample.

6. The rock mechanics test system with impact loading-confining pressure unloading according to claim 1 , wherein the pressure chamber is made of a transparent material, and the side wall of the pressure chamber is installed with a door that can be opened and closed; the inside of the pressure chamber is installed with a passage for a signal transmission line.

7. A method for using the rock impact loading-confining unloading pressure rock mechanics test system of claim 1 comprising the following steps:
step 1: make square sample;
step 2: place the sample into a pressure chamber, apply pre-tightening force to the sample, and set a limit value of an unloading controller of the confining pressure unloading unit;
step 3: apply axial compression and confining pressure to the sample, apply impact load to the sample after reaching a set pressure value;
step 4: the unloading controller accepts information from a first pressure sensor to determine whether the current pressure value is greater than the limit value; if not, continue to increase the impact load, if so, the confining pressure unloading unit will remove the confining pressure on one side of the sample;
step 5: a high-speed camera records the deformation and destruction process of the sample on one side, and the data analysis unit obtains the stress-strain curve of the sample by processing and analyzing the data from the monitoring unit.

8. The method for using the rock impact loading-confining unloading pressure rock mechanics test system according to claim 7 , wherein an unloading confining pressure process of the confining pressure unloading unit includes: the unloading controller controls baffles in pulley grooves at the end of the piston rods of the confining pressure unloading hydro-cylinder to open, so that pulleys connected to a second lateral pressure head slide along the pulley grooves.

9. The method for using the rock impac

Assignees

• Univ Shandong Science & Tech

Inventors

• Liu Xuesheng
• Song shilin
• Tan Yunliang
• Fan Deyuan
• Ning Jianguo
• Gu Qingheng
• Jiang Ning
• Wang Jun
• Xu Qiang

Classifications

• G01N2203/0026

  Combination of several types of applied forces · CPC title

• G01N3/307

  generated by a compressed or tensile-stressed spring; generated by pneumatic or hydraulic means · CPC title

• G01N2203/0048

  Hydraulic means · CPC title

• G01N3/12 Primary

  Pressure testing · CPC title

• G01N3/30

  by applying a single impulsive force, e.g. by falling weight · CPC title