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可溶盐富集是造成山西大同云冈石窟砂岩表面风化、结构破坏及强度降低的重要地质病害之一。采取云冈石窟造像层砂岩,使用芒硝对该砂岩进行了劣化模拟试验。在可溶盐反复结晶过程中,对样品进行实时变形监测,并对循环过程中质量衰减、强度变化、孔隙分布等进行测试与分析。结果表明,可溶盐的发育是导致石窟表面粉化脱落的重要因素,严重降低了石窟文物本体的价值;可溶盐结晶导致岩石颗粒间胶结作用破坏,增大岩石孔隙率,岩石内部结构劣化严重影响岩石的刚度与强度等力学参数;对比无水芒硝与10水芒硝两种劣化试验,云冈石窟在相对干燥季节下,可溶盐晶体发育对岩石破坏更为显著。为了预测砂岩长期劣化过程,在试验数据基础上,初步建立起孔隙增长的对数模型和强度衰减的指数模型。
Soluble salt enrichment is one of the important geological diseases that cause the weathering, structural damage and strength reduction of sandstone in Yungang Grottoes of Datong, Shanxi Province. Taking the sandstone of the imaging layer of Yungang Grottoes, the sandstone was degraded with Glauber’s salt. In the process of recrystallization of soluble salt, real-time deformation monitoring of samples was carried out, and the quality attenuation, strength change and pore distribution were tested and analyzed during the cycle. The results show that the development of soluble salt is an important factor leading to the powdering and shedding of the surface of the grottoes, which seriously reduces the value of the caves’ cultural relics. The soluble salt crystals lead to the destruction of the intergranular cement, increasing the porosity of the rock and the deterioration of the internal structure of the rock Seriously affecting the mechanical parameters such as the stiffness and strength of the rock. Comparing with the two deteriorating tests of anhydrous thenardite and thenardite, the development of soluble salt crystals in the Yanyang Grottoes is more pronounced under relatively dry season. In order to predict the long-term sandstone deterioration process, based on the experimental data, a logarithmic model of pore growth and an exponential model of strength attenuation were initially established.