富水隧道砂岩单轴压缩力学特性试验研究

Experimental study on mechanical properties of sandstone in water-rich tunnel under uniaxial compression

为研究隧道围岩的力学特性,文章以西北某在建富水隧道为工程背景,对施工现场砂岩进行单轴压缩试验,分析砂岩试样的峰值强度、弹性模量及应力-应变曲线上各特征应力随含水率变化的分布规律。结果表明:砂岩试样含水率随时间满足指数函数递增分布,砂岩试样峰值强度、弹性模量均随含水率增加逐渐减小;裂隙扩容应力、裂隙起裂应力和裂隙闭合应力同样随含水率增加逐渐减小,在试样浸水初期(0~18 h),三者降幅分别为8.07%、8.79%和8.62%,分别占总降幅的85.23%、94.20%和95.95%,表明岩石在浸水初期劣化最为严重。研究结论可为富水隧道施工提供可靠的试验依据。

In this study, with a water-rich tunnel under construction in the northwest China as the engineering background, uniaxial compression tests on sandstone at the construction site were conducted in order to analyze the mechanical characteristics of the surrounding rock of the tunnel. The peak strength, elastic modulus, and the distribution law of the characteristic stress on the curve with the change of moisture content stress-strain were analyzed. The results showed that the moisture content of the sandstone sample increased exponentially with time, and the peak strength and elastic modulus of the sandstone sample gradually decreased with the increase of the water content. The crack expansion stress, crack initiation stress, and crack closure stress also increased gradually with the decrease of the moisture content. At the initial stage of immersion time(0~18 h), the declines of the three were 8.07%, 8.79%, and 8.62%, respectively, accounting for 85.23%, 94.20%, and 95.95% of the total decrease, indicating that the rock deteriorated in the initial stage of water immersion is the most serious. The conclusions can provide a reliable test basis for the construction of water-rich tunnels.