高密度电阻率法在敦煌莫高窟水汽调查中的初步应用

Elementary Application of the High Density ResistivityMethod in Investigation of Moisture at the Mogao Grottoes

敦煌莫高窟壁画受自身材质和自然环境等的影响,产生起甲、酥碱、空鼓、壁画大面积脱落等多种病害,多项研究已经证明,这些病害主要是由水盐运移导致的,而水汽是激活和导致盐分运移的主要因素。我们使用高密度电阻率法对石窟围岩状况、莫高窟窟前林带区和崖顶降水入渗前后进行了现场测定,结果表明:(1)莫高窟后部崖体从表面到深度100m的地层不存在自由水;(2)莫高窟窟前林带灌溉水通过表层堆积物向崖面渗透,使洞窟岩体内的水汽含量增高,有激活盐分的可能;(3)少量的降水依然能以较慢的速度通过渗透性较好的地层或崖体裂隙渗透到洞窟的顶部,激活岩体和地仗内的盐分,导致壁画病害的发生。

Influenced by the material and natural environment, The wall paintings of Mogao grottoes have many diseases: flaking, disruption, detachment and loss, and many researches have proved that these diseases are caused by moving of salt, however the moisture is the main factor for the activation and moving of the salt. We try to investigate effect of moisture from the rock around the grottoes, the irrigation water of trees before the grottoes and rain by the high density resistivity Method. Then we found: 1) The free water does not exist at the stratum of the cliff behind of the grottoes from the surface to the depth of 100m; 2) The moisture which is transformed by irrigation water maybe moves to direction of the cliff through the loose surface deposit, and makes the content of the moisture of in the grottoes increased, then the salt can be activation; 3) The moisture which come from rain can move to the top of the grottoes through the loose stratum or cracks of cliff in a slow speed, the salt in the rock and plaster can be activation and cause the disease of wall paintings.