Method for measuring dynamic full-surface local strain and uniformity of sand tri-axial test sample by utilizing digital image processing technology

Abstract

The invention discloses a method for measuring the dynamic full-surface local strain and the uniformity of a sand tri-axial test sample by utilizing a digital image processing technology and belongs to the technical field of soil tests. The method is implemented based on a small tri-axial testing apparatus and comprises the following steps of utilizing an external high-speed industrial camera to perform a test whole process photographing on the surface of the tri-axial test sample after speckle treatment, and acquiring whole process image data; utilizing a PS to perform pretreatment on a testimage, taking a part of the image from a total field rectangular image of the test sample as a calculation stripe, and utilizing a DIC image processing technology to calculate region data of each calculation block to finally obtain center point actual displacement of each calculation block; calculating a local strain according to the obtained center point actual displacement of each calculation block; and distinguishing the total stain development uniformity of a test sample body in the test process according to each local strain, obtained by calculation, of the test sample body. By adopting the method provided by the invention, adopted equipment and devices are simple, test operation is convenient, interference on the test sample in the test process can be reduced, and various local strains of the test sample can be accurately measured.

Description

technical field [0001] The invention belongs to the technical field of geotechnical testing, and relates to a method for measuring the uniformity of strain development of a geotechnical dynamic triaxial test sample, in particular to a method for measuring the dynamic full surface variable strain and uniformity of a sandy soil triaxial sample by using digital image processing technology method. Background technique [0002] In the dynamic triaxial test of sand and soil, due to the friction constraint between the rigid sample cap and the base and the sample, during the loading process of the sample, the force on the end of the sample is inconsistent with that on the middle part, resulting in the The overall strain development of the body is not uniform. At the same time, during the dynamic loading process, due to the influence of loading frequency, permeability coefficient and other factors, the development of the overall strain of the sample is not uniform. At present, the ...

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Problems solved by technology

[0005] The purpose of the present invention is to overcome the shortcomings and deficiencies of the prior art and methods, and to provide a device that is simple in installation, convenient in test operation, and can reduce the interference to the sample during the test process, and can accurately measure the local strain of the sample at the same time. method, which solves the problem of measuring the local deformation of the entire surface of the sample body under dynamic conditions, the problem of large deformation measurement of the sample body under dynamic conditions, and the problem of judging the influence of loading frequency and sample preparation methods on the uniformity of strain development of the sample.

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