参数非定常的软岩非线性黏弹塑性流变本构模型研究

发布时间：2018-03-01 04:00

本文关键词： 软岩非定常非线性蠕变黏弹塑本构　出处：《北京交通大学》2017年硕士论文　论文类型：学位论文

【摘要】：随着西部大开发政策的实施和经济建设步伐的加快,矿山、水电和交通等大型基础设施建设如火如荼,深部软岩建设工点越来越多,并引发了施工过程中围岩持续性的蠕变大变形灾害,对工程的长期稳定性及运营期结构安全性和使用寿命提出了严峻的挑战,依托国家自然科学基金面上项目“软岩非定常分数阶微积分蠕变本构模型及深部软岩隧道施工围岩大变形控制理论研究”,本文从实验及理论的角度研究软弱岩石在长期荷载作用下的蠕变特性,建立了能正确反映软岩蠕变破坏全过程的本构模型,取得了如下成果:(1)在蠕变实验过程中,由于蠕变损伤导致岩石的力学参数逐渐弱化。本文根据泥岩在不同蠕变时间、不同轴向应力作用下的实验数据,提出了泥岩弹性模量随时间的衰减公式。(2)基于Maxwell模型,并考虑蠕变过程中弹模随时间的衰减规律,建立了一种参数非定常的软岩非线性黏弹塑性蠕变本构,并对模型参数进行了辨识。该模型可以很好地描述单轴压缩状态下泥岩蠕变全过程,三维状态下该蠕变模型对泥岩三轴压缩蠕变曲线等速和加速蠕变阶段实验结果描述不甚理想,该模型仍可以为以后的研究提供参考借鉴。(3)通过重新定义一个新的非线性黏壶元件,结合Bingham模型,本文提出了一个基于改进Bingham模型的软岩参数非定常的一维非线性黏弹塑性流变本构,该本构能准确描述单轴压缩蠕变下泥岩的衰减、稳态和加速蠕变阶段。(4)将所建立的基于改进Bingham模型的蠕变本构方程推广到三维状态,并根据泥岩三轴蠕变试验数据对该三维模型进行了参数辨识和验证,模型计算结果与实验数据吻合地比较理想,证明了所建立的基于改进Bingham模型的流变本构方程的正确性与合理性。且参数相对较少,组合形式简单,参数易于辨识,有利于在以后工程实践中推广应用,具有重要实际意义。(5)将所建立的基于改进Bingham模型的流变本构与传统Bingham模型、未考虑参数非定常的本模型、改进的西原模型和河海模型在同等实验条件下进行了对比,深入分析了本文所提新模型的特征和优缺点。
[Abstract]:With the implementation of the western development policy and speed up the pace of economic development, mining, large-scale infrastructure construction like a raging fire of hydropower and transportation, construction of deep soft rock site more and more, and led to the construction process of rock creep persistent large deformation disasters, poses a severe challenge to the long-term stability and service life and operation the structure of safety engineering, relying on the National Natural Science Fund Project "on the surface of the unsteady fractional calculus creep constitutive model and deep soft rock tunnel surrounding rock of soft rock large deformation control theory, this paper studies the creep characteristics of soft rock under long-term loading from the experimental and theoretical point of view, to establish a to correctly reflect the constitutive model of soft rock creep damage, the achievements are as follows: (1) in the creep test, the creep damage caused due to rock mechanics parameters gradually fade . according to the mudstone under different creep time, different axial experimental data of the stress under the action of the proposed attenuation formula of mudstone elastic modulus with time. (2) based on the Maxwell model, and considering the creep process of shot mode attenuation with time, a non parameter nonlinear ordinary viscoelastic soft rock plastic creep constitutive model, and the parameters are identified. The model can well describe the whole process of mudstone creep under uniaxial compression, the creep model under 3D condition on the creep curve of mudstone and isokinetic three axial compression test results describe the accelerated creep stage is not ideal, the model can provide a reference the research for the future. (3) by redefining a new nonlinear dashpot element, combined with the Bingham model, this paper proposes a soft rock parameters based on improved Bingham model of unsteady one dimensional linear viscoelastic plasticity The rheological constitutive, the constitutive model can accurately describe the attenuation of mudstone under uniaxial compression creep, steady and accelerated creep stage. (4) will be established based on improved Bingham model of creep constitutive equation was applied to three-dimensional state, and according to the parameter identification and validation of the 3D model of three axis creep test data of mudstone and the calculation results of the model agree with the experimental data to prove the ideal, the rheological constitutive equation based on improved Bingham model is correct and reasonable. And the relatively few parameters, combined with simple form, easy parameter identification, favorable in the future engineering practice application, has important practical significance. (5) will the rheological constitutive model based on improved Bingham model and traditional Bingham model, the parameters of the unsteady model do not consider the Xiyuan model and the improved model of Hehai were compared under the same experimental conditions, The characteristics and advantages and disadvantages of the new model proposed in this paper are deeply analyzed.

【学位授予单位】：北京交通大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TU45

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