The impact of water content on the strength of sedimentary rocks is a critical area of research, particularly in the contexts of disaster prevention and the construction of underground structures. Despite numerous factors being identified as contributors to the strength variations in sedimentary rocks caused by water content, a comprehensive understanding remains elusive. Moreover, only a limited number of cases have been discussed on strength changes in these rocks during water transport processes. In this study, one-dimensional water transport experiments were conducted during the drying process on Neogene tuff samples from Japan. The experiments focused on the unsaturated permeation of the porous media and analyzed the variations in advection and diffusion terms relative to saturation changes at multiple points. During the drying process, water transfer occurred primarily through diffusion, although advection was significant in the early stages to equilibrate the hydraulic head at the center of the specimen. Furthermore, the same tuff samples, with adjusted water content during the drying process, were tested using Brazilian and uniaxial compression methods to examine the variations in strength properties owing to the variations in water content. By comparing these results with the water transport data, we observed that significant alterations in strength occurred after the convergence of the advection term. It was shown for the first time that the decrease in strength of tuff occurs only during the water diffusion phase. These results are expected to be applied to more accurate evaluation of rock mass stability and advanced numerical analysis.

中文翻译：

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干燥过程中不饱和凝灰岩中水分传输的强度变化


含水量对沉积岩强度的影响是一个关键研究领域，尤其是在防灾和地下结构建设的背景下。尽管许多因素被确定为导致含水量引起的沉积岩强度变化的原因，但仍然难以全面了解。此外，关于这些岩石在水运输过程中的强度变化的案例有限。在本研究中，对来自日本的 Neogene 凝灰岩样品在干燥过程中进行了一维水传输实验。实验侧重于多孔介质的不饱和渗透，并分析了相对于多个点的饱和度变化的平流和扩散项的变化。在干燥过程中，水转移主要通过扩散进行，尽管在早期阶段对流很重要，以平衡试样中心的水力头。此外，使用巴西和单轴压缩方法对在干燥过程中调整含水量的相同凝灰岩样品进行了测试，以检查由于含水量变化而导致的强度特性变化。通过将这些结果与输水数据进行比较，我们观察到在平流项收敛后强度发生了显着变化。首次表明凝灰岩强度的降低仅发生在水扩散阶段。这些结果有望应用于更准确的岩体稳定性评估和高级数值分析。