Rock direct shear apparatusAs a key equipment for determining the shear strength of rocks, it is widely used in geological exploration, tunnel construction and other scenarios. The loading system, data acquisition module, and mechanical structure are susceptible to malfunctions caused by working conditions. If not handled in a timely manner, it can directly lead to distortion of experimental data. The following outlines diagnostic strategies and quick solutions for four types of high-frequency faults to assist in the efficient operation of equipment.
1、 Loading exception: No response or large fluctuations in pressure
Fault phenomenon: After starting the loading program, there is no pressure reading, or the pressure value fluctuates frequently (beyond ± 5% error range), making it impossible to maintain the set load.
Diagnostic direction: First check the hydraulic system, then verify the power supply chain. When the oil level in the hydraulic oil tank is lower than 1/3 of the scale line, insufficient oil suction from the oil pump will cause pressure loss; Loose oil pipe joints and aging sealing rings can easily cause oil leakage, leading to a sudden drop in pressure; Deviation of the power supply voltage from 220V ± 10% will interfere with the output of the servo motor, resulting in unstable loading.
Exclusion method: Supplement the same type of anti-wear hydraulic oil to the standard scale; Tighten the oil pipe joint with a wrench and replace the aging nitrile rubber sealing ring; Measure the voltage with a multimeter. If there is a large fluctuation, connect the stabilized power supply and restart the device.
2、 Data bias: Discrete or low intensity results
Fault phenomenon: The CV value of the same batch of samples is greater than 10%, or the shear strength is much lower than the reference value in the geological report.
Diagnostic direction: Focus sensor calibration and sample installation. Pressure sensors that have not been calibrated for over a year are prone to data drift; If the angle between the displacement sensor and the shear direction is greater than 5 °, the displacement amount will be misread; If the sample is not centered and the flatness of the upper and lower surfaces is greater than 0.1mm, it will result in uneven stress and premature local failure.
Exclusion method: calibrate the pressure sensor with a standard force gauge (error ≤ 1%); Adjust the displacement sensor with a ruler to be parallel to the cutting direction; The surface of the sample is polished flat with sandpaper and fixed in the center with the help of a positioning fixture.
3、 Mechanical jamming: The cutting box is not moving smoothly
Fault phenomenon: The shear box was stuck and the speed was uneven during the test, and it could not reset automatically after the test.
Diagnostic direction: Focus on inspecting the guide rail and transmission components. Residual rock debris and oil stains on the guide rail will increase friction; If the ball screw is not greased for more than 6 months, the transmission will be obstructed; The electromagnetic lock of the cutting box is not powered off and the locking mechanism is not released, which will limit its movement.
Exclusion method: Clean the debris on the guide rail with a brush, wipe off the oil stains with alcohol, and apply lithium based grease; Remove the end cap of the ball screw and grease it, then manually rotate it to ensure smooth operation; Disconnect the power supply of the electromagnetic lock, manually reset the shear box, and if it is stuck, disassemble and clean the screw to remove foreign objects.
4、 Software error: abnormal data collection
Fault phenomenon: The collection software frequently crashes or the test data cannot be recorded or exported.
Diagnostic direction: Check software compatibility and hardware connections. Mismatch between software version and device firmware, insufficient computer memory, or virus infection can cause abnormal operation; Loose USB/RS485 data transmission cable may interrupt the data link.
Exclusion method: Uninstall old software and install a compatible version provided by the manufacturer; Re plug or replace the data transmission cable; Close the computer backend program, antivirus and restart the software. If it doesn't work, switch to a backup computer for testing to determine if it's a hardware issue.
Daily cleaning of guide rails, calibration of sensors, quarterly inspection of hydraulic systems and lubrication status, following the troubleshooting principle of "hardware first, software second, intuitive first, precision second", can significantly reduce the occurrence rate of failures, ensure reliable test data, and provide accurate basis for engineering design.