宋洋, 李永启, 王韦颐, 刘金明. 加锚节理岩体剪切蠕变特性及其本构模型分析[J]. 煤炭学报, 2020, 45(4). DOI: 10.13225/j.cnki.jccs.2019.1428
引用本文: 宋洋, 李永启, 王韦颐, 刘金明. 加锚节理岩体剪切蠕变特性及其本构模型分析[J]. 煤炭学报, 2020, 45(4). DOI: 10.13225/j.cnki.jccs.2019.1428
SONG Yang, LI Yongqi, WANG Weiyi, LIU Jinming. Shear creep characteristics and constitutive model analysis of jointed rock mass[J]. Journal of China Coal Society, 2020, 45(4). DOI: 10.13225/j.cnki.jccs.2019.1428
Citation: SONG Yang, LI Yongqi, WANG Weiyi, LIU Jinming. Shear creep characteristics and constitutive model analysis of jointed rock mass[J]. Journal of China Coal Society, 2020, 45(4). DOI: 10.13225/j.cnki.jccs.2019.1428

加锚节理岩体剪切蠕变特性及其本构模型分析

Shear creep characteristics and constitutive model analysis of jointed rock mass

  • 摘要: 深部岩体地质环境复杂,节理岩体破坏机理不明确制约深地工程发展,为研究深部节理岩体的剪切破坏,尤其是塑性剪切破碎带的变形破坏,通过采用相似材料模拟试验和细观CT扫描技术相结合的方法,对不同法向应力下加锚节理岩体分级剪切蠕变试验过程进行研究;引入新型元件对原有模型进行修正,并采用剪切蠕变试验与三维重构宏细观结合的方法对复合流变模型中孔隙体积分数进行求解。研究表明:① 在节理岩体剪切蠕变试验中,瞬时蠕变变形量与法向应力呈负相关,衰减蠕变时间与法向应力呈正相关;② 研究发现剪切蠕变试验中稳态蠕变时间与试件破坏时间的比值时间因数M不随法向应力的提高变化,视为岩体固有属性;试验中试件的时间因数M均大于84%,即稳态蠕变时间在整个试件破坏过程中占比高。通过对不同岩体强度下时间因数M与孔隙体积分数f进行统计分析可知:时间因数M随岩体强度的提高呈现增加的趋势,孔隙体积分数f随时间因数M提高线性增加,从而实现利用时间因数M对节理岩体破碎程度的定量表征;③ 传统西原模型能够准确描述节理岩体剪切蠕变的衰减阶段和稳态阶段,对加速阶段的描述与实际不符,为准确描述节理岩体剪切蠕变全程,引入GTN模型对传统西原体进行修正,得到描述加锚节理岩体剪切蠕变全程的复合流变模型,通过对复合流变模型与试验曲线进行验证,说明复合流变模型在描述节理岩体剪切蠕变曲线的加速阶段时优于传统西原体。

     

    Abstract: The geo-environment of deep rock mass is complex,and the development of deep earth engineering project is restricted by the uncertainty of failure mechanism of joint rock mass. In order to study the shear failure of deep joint rock mass,especially the deformation failure of plastic shear fracture zone,a study on the test process for the graded shear creep of bolt discontinuous rock under different normal stresses is implemented by the adoption of similar materi- al simulation test combined with micro CT scanning technology. A new element is introduced to modify the original model and the pore volume fraction in the composite rheological model is solved through the shear creep test and the 3D macro-meso reconstruction. It can be found from the study that:① In the shear creep test of jointed rock mass,the instantaneous creep deformation is negatively related to the normal stress,and the decay creep time is positively related to the normal stress;② It is found that the ratio time factor M of the steady-state creep time to the failure time of the test piece does not vary with the increase of the normal stress,which is regarded as the inherent property of rock mass; in the test,the time factor M of the test piece is more than 84% ,which means that the steady-state creep time accounts for a high proportion in the whole failure process of test piece. Through the statistical analysis of time factor M and pore volume fraction f under different rock strengths,it can be found that time factor M increases with the increase of rock strength,and pore volume fraction f increases linearly with the increase of time factor M,so as to realize the quantita- tive characterization of fracture degree of jointed rock by using time factor M;③ The traditional Nishihara model can accurately describe the decay stage and steady stage of shear and creep for jointed rock mass,but the description of ac- celerating stage doesn’t match the reality. In order to accurately describe the whole process of shear creep of jointed rock mass,GTN model is introduced to modify the traditional Nishihara model,and a composite rheological model is obtained to describe the whole process of shear creep of anchored jointed rock mass. Through the verification of the composite rheological model and the test curve,it is shown that the composite rheological model is better than tradi- tional Nishihara model when describing the accelerating stage of shear creep curve of joint rock mass.

     

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