深部软弱地层TBM围岩力学行为试验研究

发布时间：2018-11-25 13:29

【摘要】：为揭示TBM深部软弱围岩变形破坏力学特性,开展了反映深埋隧道TBM机械开挖卸荷本质——高初始围压下缓慢准静态卸荷这一卸荷特征的砂质泥岩三轴卸围压试验,研究结果表明:缓慢卸荷条件下的岩石峰前应力-应变曲线接近于常规三轴压缩峰前应力-应变曲线,卸荷屈服阶段产生损伤扩容,侧向变形加速增长,从体积压缩开始转向扩容;应力达到峰值强度后,岩石首先发生1~2级脆性跌落,随着围压继续缓慢卸荷,岩石沿一条斜率较小的近似斜直线发生伴随有多级次生微破裂的线性应变软化;岩石变形全过程由弹性变形段、峰前卸荷损伤扩容段、峰后脆性跌落段、含有多级微破裂的线性应变软化段以及残余强度阶段组成;岩石缓慢卸荷发生宏观张剪复合破坏,并伴有轴向劈裂裂纹,破裂断面为由许多劈裂裂纹相互贯通形成具有一定宽度的剪切带,剪切带内劈裂的岩片在轴向挤压力和沿破裂面的剪切力共同作用下被挤压和摩擦成许多细颗粒和岩粉。
[Abstract]:In order to reveal the deformational and destructive characteristics of deep soft surrounding rock in TBM, a triaxial confining pressure relief test of sandy mudstone is carried out, which reflects the unloading nature of deep buried tunnel TBM mechanical excavation--slow quasi-static unloading under high initial confining pressure. The results show that the stress-strain curve of rock under slow unloading is close to that of the conventional triaxial compression pre-peak stress-strain curve, and the damage is expanded during unloading and yielding stage, and the lateral deformation increases rapidly. From volume compression to capacity expansion; When the stress reaches the peak strength, the rock first occurs 1 ~ 2 grade brittle drop. With the confining pressure continuing to unload slowly, the rock takes place along an approximate oblique straight line with a small slope, accompanied by linear strain softening with multistage secondary microfracture. The whole process of rock deformation consists of elastic deformation section, pre-peak unloading damage expansion section, post-peak brittle drop section, linear strain softening stage with multi-stage micro-fracture and residual strength stage. Macroscopic tensile and shear composite failure occurs in slow unloading of rock, accompanied by axial splitting crack, and the fracture section is formed by a shear band with a certain width through which many split cracks cross each other. Under the combined action of axial extrusion force and shear force along the fracture surface, the split rock pieces in the shear zone are squeezed and rubbed into a lot of fine particles and rock powder.
【作者单位】：中国科学院武汉岩土力学研究所岩土力学与工程国家重点实验室;武汉大学土木建筑工程学院水工岩石力学教育部重点实验室;中国煤炭科工集团西安研究院有限公司;
【基金】：国家重点基础研究发展计划(973)资助项目(2014CB046904) 国家自然科学基金资助项目(41130742,41102198)
【分类号】：U451.2

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