不同初始卸荷水平对深埋砂岩力学特性影响规律试验研究

发布时间：2018-05-25 02:35

本文选题：岩石力学 + 卸围压试验　；参考：《岩土力学》2017年11期

【摘要】：深部岩石开挖等工况诱发的不同初始卸荷水平对其力学特征影响明显,基于对砂岩进行常规三轴压缩试验和不同初始卸荷水平的三轴卸荷试验,研究了高应力加、卸荷条件下砂岩的强度、变形及扩容特征。研究发现:在同一初始围压条件下,初始卸荷水平越高,围压降低的越小,岩样达到破坏所经历的卸围压过程越短。随着初始围压的增大,不同卸荷水平下的统一围压降参数η基本是增加的,表明在高应力状态岩样需要更大的围压卸荷量才会破坏。随初始卸荷水平的提高,凝聚力c呈指数关系增长,内摩擦角φ呈多项式关系减小。卸围压的两个阶段,侧向应变增量Δε_3都比轴向应变增量Δε_1大,表现为明显的侧向扩容。初始卸荷水平越低,其最大剪胀角越大,扩容效应越明显。扩容指标I_d与围压呈幂函数型关系,与初始卸荷水平呈二次函数关系。基于对试验数据的拟合,对不同初始卸荷水平作用的砂岩的摩尔-库仑准则表达式进行了修正。
[Abstract]:Different initial unloading levels induced by deep rock excavation have obvious influence on its mechanical characteristics. Based on the conventional triaxial compression test and triaxial unloading test of sandstone at different initial unloading levels, high stress loading is studied. Characteristics of strength, deformation and expansion of sandstone under unloading conditions. It is found that under the same initial confining pressure condition, the higher the initial unloading level is, the smaller the confining pressure is, and the shorter the confining pressure process is when rock samples reach failure. With the increase of initial confining pressure, the uniform confining pressure drop parameter 畏 is basically increased at different unloading levels, which indicates that rock samples in high stress state need larger confining pressure unloading amount to destroy. With the increase of the initial unloading level, the cohesive force c increases exponentially and the internal friction angle 蠁 decreases in a polynomial relationship. The lateral strain increment 螖蔚 3 is larger than the axial strain increment 螖蔚 1 in the two stages of unloading the confining pressure, showing obvious lateral expansion. The lower the initial unloading level is, the larger the maximum shear expansion angle is and the more obvious the expansion effect is. The expansion index I _ d has a power function relationship with the confining pressure and a quadratic function relationship with the initial unloading level. Based on the fitting of experimental data, the Mohr Coulomb criterion expression of sandstone with different initial unloading levels is modified.
【作者单位】：重庆大学煤矿灾害动力学与控制国家重点实验室;中铁十一局集团第五工程有限公司;重庆工商大学管理学院;重庆市高新工程勘察设计院有限公司;
【基金】：煤矿灾害动力学与控制国家重点实验室自主研究课题(No.2011DA105287-MS201208) 中央高校基本科研业务费资助(No.CDJXS12201106)~~
【分类号】：TU45

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