| Abstract (English): |
[Objective] The schistosity plane, a common weak structural feature in schist formations, serves as a conduit for water transfer and storage and is an active zone for water-rock interaction within schist. However, under the cyclical conditions of rainfall and evaporation, the mechanical properties of the schistosity plane tend to deteriorate. This degradation reduces the stability of schist slopes and contributes to frequent geological hazards such as landslides and collapses. Hence, conducting experimental research on the degradation of schistosity planes under dry-wet cycles is essential. Such research aims to uncover the patterns of degradation, vital for long-term stability assessments of schist slopes, and to nurture students' ability to integrate theory with practical application. [Methods] In this study, cylindrical samples with an aspect ratio of 1∶1 were prepared and subjected to dry-wet cycle treatments. During the drying phase, the samples were exposed to a temperature of 105 ℃ for 24 hours, while for wetting, the free water absorption method was employed, during which the samples were soaked for 24 hours. Subsequently, direct shear tests were conducted on the samples after 0, 1, 3, 5, 10, 15, and 20 cycles of dry-wet treatment, with normal stress levels set at 3, 6, 9, 12, and 15 MPa, respectively, to determine the corresponding peak shear stress. Following the Mohr-Coulomb failure criterion, cohesive force and internal friction angle of the schistosity plane were fitted. Additionally, the total deterioration degree and stage deterioration degree were calculated using respective deterioration degree formulas. Finally, the apparent changes in the schist samples were observed, and the deterioration mechanism was elucidated by correlating it with the law of shear strength. [Results] The experimental findings revealed the following: 1) The degradation rate of peak shear stress, cohesion force, and internal friction angle was more rapid and pronounced in the initial stages but slowed down and became smaller in the later stages. 2) Following 20 cycles of dry-wet treatment, cohesion decreased by 49.05%, the internal friction angle decreased by 15.34%, and cohesion decreased approximately 3.2 times more than the internal friction angle. 3) gradually, the schistosity planes exuded yellowish-brown materials, staining the samples. This manifestation made the schistosity planes more apparent, leading to the gradual development of cracks along these planes, which extended into the rock's interior. 4) The schistosity planes served as conduits for water ingress and egress, facilitating the dissolution and removal of argillaceous cement and soluble minerals between the planes. Consequently, the cementation and cementation area between the schistosity planes gradually decreased, leading to a progressive deterioration in shear resistance. [Conclusions] Through this experiment, the deterioration law of the shear strength of the schistosity plane under dry-wet cycles and the deterioration mechanism can be obtained. Furthermore, experimental teaching holds the potential to enhance students' theoretical comprehension and practical skills, fostering their innovative thinking in scientific inquiry and their capacity to integrate theory with practice. Moreover, integrating ideological and political elements into the experiment can inspire students to appreciate the beauty of science, thereby stimulating their enthusiasm for professional learning and scientific research. [ABSTRACT FROM AUTHOR] |
| Abstract (Chinese): |
为揭示片岩片理面在干湿循环作用下抗剪性能劣化规律, 选取云母石英片岩设计相应的直剪实验方 案进行研究, 并将该方案应用于实验教学。实验结果表明：干湿循环作用下, 片理面抗剪性能劣化明显, 干 湿循环20 次后, 粘聚力和内摩擦角分别下降49.05%、15.34%, 粘聚力下降幅度约为内摩擦角的3.2 倍;片 理面不断渗出黄褐色物质浸染岩样, 使片理面逐渐显化, 且逐渐沿片理面产生裂隙并不断向岩石内部扩展发 育;片理面是水进出片岩内部的良好通道, 水可将片理面间的泥质胶结物和可溶性矿物溶解并带出, 使得片 理面间胶结物及胶结面积逐渐减少, 抗剪性能逐渐劣化。该实验教学对培养学生科研创新思维及理论联系实 际能力具有重要意义。 [ABSTRACT FROM AUTHOR] |
