莫高窟壁画地仗土-水特征曲线的测定与拟合  

Measurement and curve fitting for soil-waterer characteristic curve of mural plaster at Mogao Grottoes

作　　者：谌文武[1,2] 贾全全 童艳梅 CHEN Wen-wu;JIA Quan-quan;TONG Yan-mei(School of Civil Engineering and Mechanics,Lanzhou University,Lanzhou,Gansu 730000,China;Key Laboratory of Mechanics on Disaster and Environment in Western China of Ministry of Education,Lanzhou University,Lanzhou,Gansu 730000,China)

机构地区：[1]兰州大学土木工程与力学学院,甘肃兰州730000 [2]兰州大学西部灾害与环境力学教育部重点实验室,甘肃兰州730000

出　　处：《岩土力学》2020年第5期1483-1491,共9页Rock and Soil Mechanics

基　　金：甘肃省科技重大专项(No.18ZD2FA001)。

摘　　要：壁画的病害对壁画的长期保存和日常维护造成了极大的威胁,水带动易溶盐的迁移是导致壁画病害最主要的原因之一。地仗层作为壁画最直接的载体,其土-水特性关乎着壁画病害的形成与发育。为了研究壁画地仗层的土-水特性,根据莫高窟壁画地仗的物质组成制作了模拟地仗,采用压力板法和蒸汽平衡法分别对模拟地仗进行土-水特性试验,获得了全吸力范围的壁画地仗的土-水特征曲线,并用Van Genuchten(VG)模型和Fredlund-Xing(FX)模型对土-水特征曲线进行拟合。试验结果表明:不同组分的模拟地仗试样的土-水特征曲线有所差异,粗泥层与细泥层土-水特征曲线形态上差异并不明显;同等吸力下粗泥层含水率高于细泥层,在高吸力段粗泥层具有突变性释水的特点;对高吸力段地仗试样土-水特征曲线变化趋势的分析表明,在日常维护中莫高窟洞窟内湿度不应高于58%,湿度宜保持稳定,不应有较大波动;综合全吸力段上的试验数据进行拟合可以获得精度较高的壁画地仗的土-水特征拟合曲线。Mural plaster deterioration poses great threat to the long-term preservation and daily maintenance. The migration of soluble salts by moisture movement is one of the most important factors that causes mural plaster deterioration. The plaster plays an important role in supporting the murals. The soil-water characteristic of the mural plaster is related to the formation and development of mural deterioration. In order to study the soil-water characteristic curve(SWCC) of mural plaster in full suction range, laboratory reconstituted plasters were prepared by the same materials as the mural plaster in Mogao Grottoes, and the pressure plate test method and vapor equilibrium technique were employed. The SWCC test data was fitted by van Genuchten(VG) model and Fredlund Xing(FX) model. The SWCC of the reconstituted plaster samples with different compositions showed different characteristics, while the morphological differences between the coarse plaster and the fine plaster on the SWCC were not obvious. Under the same suction condition, the moisture content of the coarse plaster is higher than that of the fine plaster, and the coarse plaster has the characteristics of rapid release of moisture in the high suction range. By analyzing the trend of the SWCC in the high suction range, it is recommended that the humidity in the Mogao Grottoes should not exceed 58% in daily maintenance, and the humidity should be stable with no major fluctuations. Based on the experimental data in the full suction range, highly accurate SWCC can be obtained.

关 键 词：莫高窟 壁画地仗 土-水特征曲线 压力板法 蒸汽平衡法 全吸力段 

分 类 号：TU411[建筑科学—岩土工程]