Zeng Weihao, Chen Zhenghong, Xie Yunpeng, Chen Qiunan
School of Civil Engineering, Hunan University of Science and Technology, Xiangtan 411201, China.
Research Center of Geotechnical and Structural Engineering, Shandong University, Jinan 250061, China.
Materials (Basel). 2023 Jul 22;16(14):5163. doi: 10.3390/ma16145163.
Tunnel projects in the southwestern mountainous area of China are in full swing. According to the tunnel burial depth, structural characteristics, and chemical erosion environments of the Lixiang railway tunnel, carbonaceous slate specimens obtained in the field were taken to experimentally investigate the physical, mechanical, and creep characteristics of the bedding's slate specimens after chemical erosion. The results of scanning electron microscopy (SEM) indicate that chemical erosion leads to internal damage in the carbonaceous slate specimens, and the internal damages are increasing with the increase of erosion days. Moreover, the specimens' ultrasonic test (UT) results prove that specimens with smaller bedding angles suffer a more serious erosion and induce more internal cracks. Under conventional triaxial compression conditions with 40 MPa of confining pressures, the conventional triaxial compressive strength (σ) decreases with the decrease of the bedding angle and the increase of erosion days, and the failure modes of the specimens are mainly controlled by oblique shear fractures and accompanied by the occurrence of slip dislocation fractures between the bedding inclination. Under creep conditions with 40 MPa of confining pressures, the final deformations of specimens are increasing with the increase of erosion days, which means the longer the erosion days, the greater the deformations. The failure modes of the specimens under creep conditions are controlled by shear fractures, and for the specimen with a 60° bedding angle and long-term erosion, there are block separations and many cavities along the shear planes. Therefore, more attention should be paid to prevent serious failure of the surrounding rock if the surrounding rock has a bedding angle of 60° or suffers long-term erosion.
中国西南山区的隧道工程正在如火如荼地进行。根据丽香铁路隧道的隧道埋深、结构特征和化学侵蚀环境，采集了现场获得的碳质板岩试样，以试验研究化学侵蚀后顺层板岩试样的物理、力学和蠕变特性。扫描电子显微镜（SEM）结果表明，化学侵蚀导致碳质板岩试样内部损伤，且内部损伤随着侵蚀天数的增加而增加。此外，试样的超声测试（UT）结果证明，顺层角度较小的试样遭受的侵蚀更严重，产生的内部裂纹更多。在围压为40 MPa的常规三轴压缩条件下，常规三轴抗压强度（σ）随着顺层角度的减小和侵蚀天数的增加而降低，试样的破坏模式主要受斜剪裂缝控制，并伴有顺层倾角间滑移错位裂缝的出现。在围压为40 MPa的蠕变条件下，试样的最终变形随着侵蚀天数的增加而增大，即侵蚀天数越长，变形越大。试样在蠕变条件下的破坏模式受剪切裂缝控制，对于顺层角度为60°且长期侵蚀的试样，沿剪切面存在块体分离和许多空洞。因此，如果围岩顺层角度为60°或遭受长期侵蚀，应更加注意防止围岩发生严重破坏。
