Method for constructing elastic-plastic-damage coupling mechanical constitutive model of rock material

Abstract

The invention discloses a method for constructing an elastoplasticity-damage coupling mechanical constitutive model of a rock material. The method comprises the following steps of obtaining the rock material on an engineering site, and manufacturing a standard cylinder sample; carrying out conventional triaxial compression mechanical tests under different confining pressures; obtaining a rock yield criterion, a plastic hardening criterion and a non-associated fluidity rule in combination with a test result; calculating a rock damage variable according to the stress-strain curve, and obtaininga rock damage evolution equation according to a damage variable-axial strain evolution rule; deriving a constitutive equation based on an elastic-plastic mechanics theory and an irreversible thermodynamic damage constitutive theory; combining the test data to obtain model parameters; writing the mechanical model into a UMAT subprogram, embedding the UMAT subprogram into ABAQUS finite element software, and carrying out triaxial test numerical simulation, so as to verify and improve the model. The method is clear in mechanical significance, simple in parameter acquisition, wide in application range and relatively high in accuracy.

Description

technical field [0001] The invention belongs to the field of geotechnical engineering, and in particular relates to a method for constructing a rock material elastic-plasticity-damage coupled mechanics constitutive model. Background technique [0002] As the basic constituent material of rock mass, rock engineering, energy mining, underground storage and analysis of geological phenomena require an in-depth understanding of its mechanical properties. Constitutive model construction is an in-depth exploration of rock mechanical properties, and it is also a key link connecting laboratory tests, theoretical analysis and simulation. Accurate mechanical constitutive can not only describe the deformation mechanism of rock, but also reflect its internal damage mechanism. As a complex natural geological body, rock itself has defects, and there are generally a large number of microscopic structures such as micro-holes and micro-cracks inside the material. Under a certain external lo...

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Problems solved by technology

Fang Zhiheng and Wang Liguan proposed a rock statistical damage constitutive model in the patent "Construction and Application of Rock Statistical Damage Constitutive Model" (201410577627.3), but the model uses Mohr-Coulomb considering the linear flow law criterion, and the damage parameter is only related to the surrounding rock pressure σ 3 Related, the actual engineering application has limitations; Sun Mengcheng and Xu Weiya disclosed a method of establishing a rock damage constitutive model based on the minimum energy consumption principle in the patent "A Method for Establishing a Rock Damage Constitutive Model Based on the Minimum Energy Consumption Principle" method, it is proposed to obtain the damage threshold and identify the model parameters through the test results and deformation parameters, which can better describe the mechanical properties of the post-yield section of rock materials, but because the plastic deformation characteristics of materials are not considered, it is only applicable to brittle rocks ; Zhou Yongqiang in the paper "Statistical Model of Rock Elastic Damage Considering the Effect of Residual Strength and Threshold Value" (Zhou Yongqiang, Sheng Qian, Leng Xianlun, et al. Statistical Model of Rock Elastic Damage Considering the Effect of Residual Strength and Threshold Value[J]. Journal of Yangtze River Academy of Sciences ,2016,(3):48- 53) constructed a rock elastic damage statistical model considering the influence of residual strength and threshold value, Wang Xuebin in the paper "Elasticity-brittleness-damage model and its application in the study of rock local failure" (Wang Xuebin, Du Yazhi, Pan Yishan, et al. Elasticity-brittleness-damage model and its application in the study of rock local failure [J]. Journal of Applied Basic and Engineering Science, 2012,20(4):642-653) An elastic-brittle-damage constitutive model. Damage is introduced into the model to consider the change of elastic modulus of brittle rocks in the process of sudden stress drop, but the above two models are not able to consider the plastic deformation of rocks; Yuan Xiaoping in the paper "Research on Rock Elastoplastic Damage Constitutive Model Based on Drucker-Prager Criteria" (Yuan Xiaoping, Liu Hongyan, Wang Zhiqiao. Research on Rock Elastoplastic Damage Constitutive Model Based on Drucker-Prager Criteria[J]. Rock and Soil Mechanics, 2012,33 (4):148-153) proposed to use volumetric strain to characterize the damage evolution of rocks, and established an elastoplastic damage model for rock materials based on the Drucker-Prager criterion. This model can simultaneously consider plastic softening and damage softening, but failed Consider the coupled relationship and interaction of plastic yielding and damage evolution

[0005] To sum up, the existing methods for constructing mechanical constitutive models of rock materials have certain defects. On the one hand, they can only consider the plastic characteristics of rock deformation, or consider the damage characteristics of rocks, but they are only applicable to Brittle rocks; on the other hand, the coupling relationship between elastic-plastic deformation and damage evolution is not considered

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