高围压高孔隙水压作用下岩石蠕变特性

发布时间：2018-02-02 22:19

本文关键词： 高围压高水压砂岩蠕变非线性蠕变模型　出处：《中南大学学报(自然科学版)》2014年06期 　论文类型：期刊论文

【摘要】：对重庆某地深部砂岩进行高围压和高孔隙水压作用下分级加载蠕变试验。结果表明:加载初期的一较短时间内,孔隙水压力在一定程度上延缓轴向变形,随后整个加载过程表现为增强岩石轴向变形。相同围压下,有孔隙水压和无孔隙水压时岩石蠕变可能存在一个相同的应力强度比阀值,当应力强度比超过该阀值后便会出现加速蠕变破坏。选取三元件广义Kelvin模型描述高围压高孔隙水压作用下加载应力低于屈服应力σs时的岩石蠕变特性,效果较为理想。基于高围压高孔隙水压作用下砂岩加速蠕变试验曲线特性,采用拟合、类比的方法引入一个二元件黏塑性模型,将其与三元件广义Kelvin模型串联组成一个新的可以描述岩石加速蠕变全过程的非线性黏弹塑性蠕变模型。采用基于Quasi-Newton非线性优化算法(BFGS)的Matlab编程,实现对高围压高孔隙水作用下岩石加速蠕变全过程曲线进行辨识,对比试验曲线和模型拟合曲线,二者吻合较好,验证非线性黏弹塑性模型的正确性。
[Abstract]:Creep tests under high confining pressure and high pore water pressure in deep sandstone in Chongqing are carried out. The results show that the pore water pressure delays axial deformation to a certain extent in a short period of time in the early stage of loading. Under the same confining pressure, the creep of rock with pore water pressure and without pore water pressure may have the same stress-intensity ratio threshold. When the stress-intensity ratio exceeds the threshold, accelerated creep failure will occur. A three-element generalized Kelvin model is selected to describe the creep characteristics of rock under high confining pressure and high pore water pressure under loading stress below the yield stress 蟽 s. Sex. Based on the characteristics of accelerated creep test curve of sandstone under high confining pressure and high pore water pressure, a two-element viscoplastic model was introduced by fitting and analogy. A new nonlinear viscoelastic-plastic creep model, which can describe the whole process of accelerated creep of rock in series with the three-element generalized Kelvin model, is constructed. The nonlinear optimization based on Quasi-Newton is adopted. Transformation algorithm (. Matlab programming. The whole process curve of accelerated creep of rock under the action of high confining pressure and high pore water is identified, and the experimental curve and the model fitting curve are compared, which are in good agreement with each other and verify the correctness of the nonlinear viscoelastic-plastic model.
【作者单位】：重庆大学土木工程学院;重庆科技学院建筑工程学院;
【基金】：国家自然科学基金资助项目(41302223) 中央高校研究生创新基金资助项目(CDJXS12200004) 重庆市基础与前沿研究计划项目(cstc2013jcyjA90004) 重庆科技学院教授、博士生导师启动基金资助项目(CK2013B27)
【分类号】：TU45
【正文快照】： 蠕变特性是岩石的一个重要力学性质,与工程的长期稳定和安全密切相关。大量工程实践表明,岩石蠕变是工程产生大变形乃至失稳的重要原因之一[1]。近年来随着基础工程建设中深长隧道不断涌现,如秦岭隧道、锦屏引水隧道、青藏铁路新关角隧道等,高地应力与高孔隙水压力作用下隧道

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