A Test Method for Complicated Unloading Stress Path of Geotechnical Materials

Abstract

The invention discloses a method for testing the complex unloading stress path of rock and soil materials, which comprises the steps of: preparing the rock and soil materials to be tested; obtaining the basic physical and mechanical properties and related parameters of the rock and soil materials to be tested; Prepare triaxial samples from rock and soil materials; carry out sample loading, pumping saturation and consolidation treatment on triaxial samples in sequence to obtain saturated and consolidated samples; set different unloading stress paths and different unloading stress ratios; Saturated and consolidated samples are subjected to unloading stress path tests; the changes of stress and strain with stress increment during the test are monitored and recorded, and the macroscopic mechanical characteristic curves of saturated and consolidated samples are obtained; after sorting out, the unloading modulus is calculated respectively , Poisson's ratio, yield trajectory and yield strength, so as to obtain the deformation characteristics and strength characteristics of rock and soil materials under complex unloading stress conditions. Beneficial effects: the stress-strain law of the geotechnical material in the complex unloading stress path state can be obtained.

Description

technical field [0001] The invention relates to a stress path test method, in particular to a complex unloading stress path test method for rock and soil materials, belonging to the field of mechanical properties of rock and soil materials under the complex unloading stress path conditions of rock and soil engineering and its application research. Background technique [0002] In the process of geotechnical engineering construction, the stress state and strain state of the soil are a complex and changing process. In order to analyze the project, we often use a certain theory (such as the Duncan model) to describe the state of the soil at a specific moment. State of stress or strain. When we regard the soil as an ideal elastic body, we think that its mechanical properties only depend on the initial and final stress state, and that it has nothing to do with the loading or unloading process, that is, it has nothing to do with the stress or strain development process. Modern no...

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Problems solved by technology

However, with the development of soil mechanics and the continuous deepening of the understanding of soil properties, conventional loading tests represented by conventional triaxial tests established under axisymmetric conditions cannot satisfy the stress-strain relationship of soil under complex stress conditions. Requirements for understanding and stable deformation analysis, test instruments and methods that can reflect the stress-strain law of soil under complex stress states and complex boundary conditions, represented by true triaxial, are emerging, such as true triaxial, GDS stress path Triaxial instrument, hollow cylinder torsional shear instrument, etc.

The stress path triaxial instrument can reflect the stress-strain relationship of the soil under different stress paths. Its working principle is clear, its development is relatively mature, and its operation is relatively simple. It is an important test tool for studying the stress-strain relationship of soil under complex stress paths. , but the corresponding test methods, especially the test methods for soil mechanical properties under the condition of complex unloading stress path, are insufficiently studied

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