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为了研究隧道施工过程中水对石膏岩的软化作用规律,以三叠系下统嘉陵江组地层中的石膏岩为研究对象,进行了不同时间的淡水浸泡软化试验研究,对石膏岩单轴抗压强度、抗剪强度、弹性模量以及泊松比随浸泡时间的变化规律进行分析。研究发现:随着浸泡时间的增长,石膏岩的单轴抗压强度、抗剪强度和弹性模量呈负指数下降趋势,而泊松比在一定条件下呈线性增加趋势;在损伤力学基础上,推导出了基于时间因素的石膏岩软化损伤演化方程,揭示了脆性系数与软化损伤变量之间的关系,建立了石膏岩在不同淡水浸泡时间下的软化深度模型,可用于判别穿越石膏层隧道开挖过程中围岩在地下水作用下的软化区域。
In order to study the law of softening effect of water on gypsum rock during the tunnel construction, the gypsum rock in the Lower Triassic Jialingjiang formation was taken as the research object, the fresh water immersion softening experiment was conducted at different times, and the uniaxial compressive stress The strength, shear strength, elastic modulus and Poisson’s ratio were analyzed with the variation of immersion time. The results show that with the increase of immersion time, uniaxial compressive strength, shear strength and elastic modulus of gypsum rock show a negative exponential downward trend, while the Poisson’s ratio shows a linear increase trend under certain conditions. On the basis of damage mechanics , The evolution equation of gypsum softening damage was deduced based on the time factor. The relationship between the brittleness coefficient and the softening damage variable was revealed, and the softening depth model of gypsum under different freshwater immersion time was established, which can be used to determine the tunnel depth Rock excavation process in the softening zone under the action of groundwater.