硬石膏岩长期膨胀性试验研究

Research on the Long-term Swelling of Anhydrite Rock

探究硬石膏原岩样遇水后的持续膨胀行为和含水状态随时间变化规律,对预测和控制硬石膏岩工程的膨胀灾害具有重要的理论和工程意义。本文针对硬石膏原岩样的长期膨胀性能开展试验。试验结果表明:①持续供水条件下,硬石膏岩可长时间持续膨胀,轴向膨胀应变及侧向膨胀应力,先快速增加,再缓慢增加,最后保持稳定速率持续增加。试验进行到第119天时,轴向膨胀应变和侧向膨胀应力分别高达2.26%和1679.95kPa。②随浸水时间增加,硬石膏岩的吸水率、结晶水率以及水化率逐渐增加,结晶水率趋向吸水率,而自由水率逐渐下降至零。基于微观膨胀机理和试验结果,建立了体积膨胀应变的时变模型,能够反映自由水和结晶水分别对体积膨胀应变影响大小。

The research on the swelling performance and water conditions changing over time of anhydrite has theoretical and engineering significance on the prediction and control of engineering disaster caused by anhydrite swelling.So a long-term swelling test were conducted.The results indicated that:①with the effect of continuous water,the axial swelling strain and lateral swelling stress increased quickly,and then increased slowly until their growth rate reached relatively stable value.The axial swelling strain and lateral swelling stress were up to 2.26%and 1679.95kPa on day 119,respectively.②the water absorption,crystal water and hydration rate increased,and the crystal water increased gradually to equal water absorption,while the free water decrease to zero.Based on the microscopic swelling mechanism and test results,the mathematical models between swelling and water condition was established.These models are able to show the influence of free water and crystallization water on volumetric swelling strain,respectively.