北京汉白玉石质文物的病害类型及病害机理研究

Damage categories and deterioration mechanism of stone cultural relics of white marble in Beijing

北京地区的石质文物众多,其中大多数石质文物的石材都是产自房山区大石窝镇的汉白玉(属于大理岩)。通过现场调查,基于国际古迹遗址理事会石质学术委员会(ICOMOS-ISCS)等提出的分类标准,对北京地区汉白玉石质文物的病害类型进行分类,并给出了具体类型的描述和照片。通过对大理岩的矿物成分和微观性质测试分析,研究了其中的剥落、崩解、结壳、溶蚀和溶孔等病害的机理,结果表明:温度变化是汉白玉表层剥落的主要原因;汉白玉中白云石矿物晶体内和晶体间的溶蚀是发生崩解的主要原因;结壳是环境污染(包括SO2和灰尘)造成的;由于方解石溶解速度大于白云石,少量方解石的首先溶解造成了溶孔,而溶蚀则是白云石的缓慢溶解造成的。相关研究为北京汉白玉石质文物的修复和保护提供了科学依据。

There are many stone relics in Beijing and most stone of them are white marble,also called Hanbaiyu,mined from Dashiwo town in Fangshan District,Beijing. Based on field investigation,the deterioration patterns of white marble stone relics in Beijing are described in detail according to the disease classification standard issued by ICOMOS-ISCS. In addition,mechanism of deterioration patterns including scaling,granular disintegration,crust,dissolution pore and erosion are analyzed through mineral and microscopic property study. The main reason of surface scaling is temperature change. The reason of granular disintegration is that dolomite mineral crystal dissolved both in and between the mineral crystals.Crust is formed by the environment pollution,especially SO2 and dust. The dissolution of calcite is faster than that of the dolomite; dissolution voids will appear firstly in calcite after the dissolution. Erosion is caused by dolomite dissolve slowly. The above study on the white marble of Beijing will provide a scientific basis for the restoration and protection of the cultural relics.