硬石膏岩膨胀力学试验研究进展及展望

Study Progress and Prospect of Swelling Mechanical Test on Anhydrite Rock

为了进一步认识和加深对硬石膏岩膨胀特性的研究,采用文献综述的方法对硬石膏岩膨胀力学试验进行了较为系统和详细的归纳与总结,分析了各因素对于硬石膏岩膨胀的影响。试验研究结果表明,岩石含水率、溶液浸泡时间、离子浓度、温度、水压等诸多因素对硬石膏岩的膨胀力学特性有着显著的影响。岩石含水率增加,岩石单轴抗压强度、弹性模量、变形模量降低,泊松比近似呈现增大的趋势。岩石单轴抗压强度与硬石膏含量、硬石膏水化率三者在空间上呈现"飞鱼"状的不规则曲面关系。岩石单轴抗压强度、抗拉强度、弹性模量和软化系数等力学参数随着浸泡时间的增加、溶液温度的上升和溶液离子浓度的增加而减小。随着水压的增大,岩石弹性模量和峰值强度增大促进岩石膨胀的激活,导致膨胀性增加。硬石膏水化为石膏引发的膨胀受温度影响较大,温度超过48.8℃时,硬石膏平衡浓度低于石膏平衡浓度,硬石膏无法水化为石膏。硬石膏岩的硬石膏含量及厚度达到一定程度时,表面水化生成的石膏作为密封保护层阻止硬石膏岩进一步水化。基于试验研究成果,对穿越硬石膏地层隧道的工程实践措施进行了分析,结合现有试验研究存在的不足,对未来硬石膏岩的研究方向进行了展望,对未来研究硬石膏岩提供一定的借鉴与指导。

In order to further understand and deepen the research on the swelling characteristics of anhydrite rock,the expansion mechanical tests of anhydrite rock are systematically and detailly summarized by using the method of literature review.The influences of different factors on the swell of anhydrite rock are analyzed.The results of swelling test show that(1)Water content of rock,immersion time,ion concentration,temperature,water pressure and other factors have significant influences on the swelling mechanical properties of anhydrite rock.With the increase of water content,the uniaxial compressive strength,elastic modulus and deformation modulus of rock decrease,and Poisson’s ratio increases approximately.(2)The relationship of uniaxial compressive strength with anhydrite content and hydration rate of anhydrite presents a"flying fish"shape in space.The mechanical parameters of rock such as uniaxial compressive strength,tensile strength,elastic modulus and softening coefficient decrease with the increase of immersion time,temperature and ion concentration.(3)With the increase of water pressure,the increase of the elastic modulus and peak strength of rock promote the activation of rock swell,resulting in the increase of expansibility.(4)The swell caused by the hydration of anhydrite into gypsum is greatly affected by temperature.When the temperature exceeds 48.8℃,the equilibrium concentration of anhydrite is lower than that of gypsum,and anhydrite will not hydrate into gypsum.(5)When the content and thickness of anhydrite reach a degree,hydrated gypsum on the surface forms a protective layer,which can prevent the anhydrite from further hydration.Based on the experimental study results,the engineering practice measures for the tunnel crossing the anhydrite stratum are analyzed.Combining the shortcomings of the existing experimental researches,the future study direction of anhydrite rock is prospected,and a certain reference of the future study on anhydrite rock is provided.