土遗址文物多相介质非均匀迁移特性及文物原位环境重建

Site relic is a very important type of cultural heritage. Many of them are suffering deterioration or even damage due to the open, large-space building layout and air-soil coupling preservation environment. The most effective way to upgrade the preservation environment is to re-establish the balance of mass and energy distribution in the coupling environment and reconstruct a primitive environment for the relics. In this application, an isolated air curtain conception is proposed to separate the open and large-space exhibition hall with funerary pit structure into enclosure and small ones. Meanwhile, an inversion temperature layer is created by the air curtain in the funerary pit to implement the steady of environment and suppress the migration of heat and mass from the air into the soil. In order to realize above research objectives, the following contents will be carried out in the application, i.e., (i) the mechanism of short-circuit migration and one-way migration of mass and energy in the system of air-relic-soil will be investigated by building a non-uniform porous medium model and the principle for the supression of the migration will be brought forward based on those mechanism, (ii) The optimal theoretical design of the air curtain system will be determined through stream function method and computational fluid dynamics method. In additional, the mechanism of the inversion temperature layer distribution in the pit will be investigated by the above numerical models, (iii) an experimental pit will be set up to validate the performance of the air curtain system. The research project provides a new idea to improve preservation environment for the existing site museum and a novel model for the design of new constructed museums.

开放式大空间展出模式与多环境介质是导致土遗址文物泛碱污损的主要原因，重建文物保存环境体系内物质与能量平衡，恢复其出土前原位环境是解决这些问题最有效途径。本项目以兵马俑与汉阳陵博物馆为例，对陶质遗址文物表面析盐、风化过程中的热质迁移特性进行基础科学研究，并提出利用隔离式空气幕系统的局部环境调控技术，实现文物保存原位环境重建。具体研究内容包括：建立非均匀多孔介质模型，研究大气-土壤-文物多介质体系内物质与能量的"短路迁移"与"单向迁移"等非均匀性运移机理，根据该机理提出抑制物质和能量通过文物本体向大气迁移的基本思路；建立隔离式空气幕的流函数解析模型与CFD模型，提出空气幕的最佳理论设计参数，阐明坑内逆温层抑制机理；搭建一个实验葬坑系统，验证所提方法正确性，获得隔离式空气幕系统对重建遗址原位环境的实际运行效果。项目研究将为改善现有遗址博物馆内文物保存环境和今后新建遗址博物馆提供一种新的思路。

我国世界遗址的大国，境内的遗址类文物非常丰富。但是很多遗址文物在保存过程中面临严重干裂、泛碱等病害，由于我们对病害产生机理及保护方法认识存在不足，因此，缺乏有效的保护方法。本项目针对我国遗址文物保存中面临的环境问题，对遗址文物的土壤-空气耦合环境内水盐迁移机理、葬坑内遗址文物保存环境的空气幕隔离及原位环境重建、遗址文物保存局部环境调控等进行研究，研究结果表明：1）水分从土遗址-空气耦合环境内从土壤向空气迁移是一个单向自发过程，迁移平衡点要求空气相对湿度达到99.96%以上；2）土遗址水盐迁移速度及干裂病害的发展过程与土遗址-空气耦合保存环境内温度与水分分布梯度成正比，重建遗址文物保存环境的平衡是缓解遗址文物病害的关键；3）利用空气幕对葬坑内文物保存环境进行隔离调控，隔离效率可以达到92%以上，并且可以实现文物保存区环境稳定；4）利用葬坑内温度逆温层分布特点，可以实现游客环境与文物保存环境独立调控，这对我们今后根据遗址文物对保存环境的特殊需求进行调控提供了理论与实验支持。通过本项目的研究，获得了一系列关于遗址文物病害发生机理与保护新技术，本项目研究所提的空气幕隔离调控技术与土遗址干裂病害补水保护技术将在分别在兵马俑博物馆和汉阳陵博物馆进行示范。同时在项目执行期间课题组成员参加学术会议8次，发表SCI论文5篇，申请国家发明专利6项（授权2项）。