摘要
冻结法作为穿越富水软岩地层的重要施工方法,冻结壁的长期稳定性对于工程安全有着至关重要的作用。蠕变破坏是诱发冻结壁变形的显著特点之一,对研究冻结岩石蠕变的特性有重要的理论和工程意义。以白垩系饱和冻结砂岩为研究对象,开展–10℃低温冻结条件下,不同围压(0、2、4、6 MPa)的三轴蠕变力学试验。分析了饱和冻结砂岩蠕变变形,根据现有黏弹塑性模型开展了参数辨识并探究蠕变参数的变化规律,基于此提出考虑温度及损伤效应的蠕变本构模型。研究结果表明:低温冻结削弱蠕变过程中颗粒间的相互胶结力,使其蠕变特征明显;而围压却在一定程度上抑制饱和冻结砂岩内部损伤的发展,导致稳态蠕变速率随围压的升高出现明显的下降趋势。随围压的增加饱和冻结砂岩的蠕变破坏形态呈现出从剪切破坏到张拉破坏再到局部塑形硬化破坏的变化过程。在黏弹塑性模型的基础上,总结蠕变参数E1、E2和η2随荷载的增加呈现先增后减的趋势,拐点为屈服应力;而参数η0在大于屈服应力后出现并呈现先增后减的趋势。结合冻结岩石蠕变数据对定义的应力-低温耦合蠕变本构模型进行了参数辨识,并将该模型的计算结果与蠕变试验数据对比,验证所建立非线性模型的正确性与合理性。
The freezing method is an important construction method for crossing water-rich soft rock formations.The long-term stability of the frozen wall plays an important role in engineering safety.Creep damage is one of the remarkable features of induced deformation of frozen walls.It is of great theoretical and engineering significance to study the characteristics of frozen rock creep.Taking the cretaceous saturated frozen sandstone as the research object,triaxial creep mechanical tests with different confining pressures(0,2,4 and 6 MPa)were carried out under the low temperature freezing condition of–10℃.The creep deformation of saturated frozen sandstone was analyzed.According to the existing viscoelastic-plastic model,the parameter identification was carried out and the variation law of creep parameters was studied.A creep constitutive model considering temperature and damage effect was then proposed.The results show that the low temperature freezing weakens the mutual cementation force between the particles during the creep process,and the creep characteristics are obvious.However,the confining pressure inhibits the development of the internal damage of the saturated frozen sandstone to some extent,resulting in the steady creep rate.The increase in confining pressure shows a significant downward trend.With the increase of confining pressure,the creep failure morphology of saturated frozen sandstone shows a change process from shear failure to tensile failure to local shape hardening failure.On the basis of the viscoelastic model,the creep parameters E1,E2 andη2 are increased first and then decreased with the increase of the load,and the inflection point is the yield stress.The parameterη0 appears after the yield stress and undergoes increase to decrease.Combined with the frozen rock creep data,the parameters of the stress and low temperature coupled creep constitutive model are identified,and the numerical results of the model are compared with the creep experimental data to verify the correctness and rationality of the established nonlinear model.
作者
魏尧
杨更社
申艳军
明锋
梁博
WEI Yao;YANG Geng-she;SHEN Yan-jun;MING Feng;LIANG Bo(School of Architecture and Civil Engineering,Xi’an University of Science and Technology,Xi’an,Shaanxi 710054,China;State Key Laboratory of Frozen Soil Engineering,Cold and Arid Regions Environmental and Engineering Research Institute,Chinese Academy of Sciences,Lanzhou,Gansu 730000,China)
出处
《岩土力学》
EI
CAS
CSCD
北大核心
2020年第8期2636-2646,共11页
Rock and Soil Mechanics
基金
国家自然科学基金(No.51774231,No.41702339)
冻土工程国家重点实验室开放课题(No.SKLFSE201713)。
关键词
白垩系冻结砂岩
蠕变
非线性
参数辨识
cretaceous frozen sandstone
creep
nonlinear
parameter identification
