利用X-CT和数字图像相关法对遗址反复干湿导致的劣化机制进行基础研究

Basic research on the mechanism of deterioration of archaeological sites due to dry-wet cycles using X-CT and digital image correlation methods

此研究是以石材和土壤所构成的考古遗址为主要研究对象。在确定石材和土壤的渗透性下,通过数字体积相关法(DVC)和数字图像相关法(DIC)对干湿劣化的环境条件进行定量的评估,并提出控制这种劣化发生的环境调整方法。为了收集基本数据,通过DIC及X射线成像技术分析从湿润到干燥的过程中丰浦硅砂的位移量实验,并在实验中,使用DIC计算样品在收缩应力下的变形分布。此外,本次实验以铁粉作为示踪剂添加至样品中,并以铁粉作为参考点计算丰浦硅砂特定范围的移动量,借此评估铁粉作为示踪剂的适用性及精确性。结果表明,通过拍摄干燥前后样品的X射线图像,并用DIC进行分析可以计算出干燥前后的变形分布。在样品中添加示踪剂也被发现有助于分析样品局部区域的移动方向及移动量。因此通过此基本数据的检验,相信将来通过X射线计算机断层扫描(X-CT)及数字体积相关法(DVC)的应用,可以用来阐明反复干湿风化的劣化机制。

This study is focused on an archaeological site composed of stone and soil.Based on the determination of the permeability of stone and soil,the environmental conditions of wet and dry deterioration are quantitatively evaluated by digital volume correlation(DVC)and digital image correlation(DIC),and environmental adjustment methods to control the occurrence of such deterioration are proposed.In order to collect basic data,experiments were conducted to analyze the amount of displacement of TOYOURA silica sand from wetting to drying by DIC and X-ray imaging technology.In the experiment,the deformation distribution of the samples under shrinkage stress was calculated using DIC.In addition,this experiment was conducted to evaluate the applicability of iron powder as a tracer by using iron powder as a reference point to calculate the amount of displacement in a specific range of TOYOURA silica sand.The results show that the deformation distribution before and after drying could be calculated by taking X-ray transmission images of the samples before and after drying and analyzing them with DIC.The addition of the tracer to the samples was also found to be useful in analyzing the direction and amount of movement in localized areas of the samples.Therefore,through the application of this technology,it is believed that it could be used to elucidate the deterioration mechanism of dry-wet cycle weathering in the future.