High-precision strain measurement system for geotechnical true tri-axial test and measurement method thereof

Abstract

The invention discloses a high-precision strain measurement system for a geotechnical true tri-axial test and a measurement method thereof. The high-precision strain measurement system comprises a large-range laser displacement sensor, a small-range laser displacement sensor, a measurement and control computer, a servo motor, a servo driver and a ball screw nut pair, wherein the small-range laser displacement sensor automatically adjustable in position and wide-range laser displacement sensor at a fixed position are matched to provide a test sample strain measurement result for the test system, the position of the small-range laser displacement sensor is adjusted by the system through the servo motor and the ball screw nut pair, and an output signal of the small-range laser displacement sensor serves as a feedback signal for a servo drive system to drag the small-range laser displacement sensor so as to perform position adjustment. The high-precision strain measurement system can achieve strain displacement measurement resolution ratio greater than 1 micron within a larger range, remarkably improve the smoothness of strain loading control process of the test system and customize the strain measurement precision of the test system.

Description

technical field [0001] The invention belongs to the technical field of geotechnical tests, and in particular relates to a high-precision strain measurement system and a measurement method thereof in the process of carrying out geotechnical true triaxial tests. Background technique [0002] The large-scale geotechnical true triaxial test system is a large-scale geotechnical test equipment used to carry out stress-strain loading tests of rock-soil models. The system uses large-thrust hydraulic equipment (such as hydraulic jacks) to squeeze rock-soil model samples from two vertical directions, front and back, and four horizontal directions, front, rear, left, and right. At the same time, it has a servo closed-loop capability and can accurately control the test. A time-domain loading curve of the amount of strain or stress in a process. By monitoring the stress and strain state change curves of the geotechnical model during the stress process, the stress failure process of the ...

AI Technical Summary

Problems solved by technology

However, limited by the working principle of the laser displacement sensor, its resolution is difficult to exceed 0.01% FS, which makes the detection accuracy of the traditional test system for the sample strain only barely reach the minimum accuracy level (0.01mm) required by the test, which limits The test measurement and control accuracy of the large-scale geotechnical true triaxial test system, as well as the further improvement of the research effect

[0005] Due to the insufficient resolution of traditional strain measurement equipment (such as laser displacement sensors), the test system cannot achieve higher strain measurement accuracy, which limits the accuracy of quantitative analysis of test results; , the strain feedback results from traditional strain measurement equipment will show a more obvious step effect, resulting in the discretization of the output control of the drive system in the time domain (for example, the sample is required to be strained at a speed of 0.01mm / min, using the resolution When using a displacement sensor with a rate of only 0.01mm, the drive system needs at least 1min to output an effective control signal), which reduces the control accuracy of the servo closed-loop and the smoothness of the curve loading during the test

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