云冈石窟水汽转化特征的初步研究

Preliminary investigation on water-vapor transfer in Yungang Grottoes

水汽的凝结是云冈石窟壁面水分的来源之一。研究水汽转化特征和石窟山体的水汽环境变化特征,对石窟文物的保护具有重要意义。本文阐述了水汽转化的基本原理,并针对石窟环境提出了凝结水的观测方法。通过在5号和9号洞窟布置监测系统,配合凝结水的观测,发现在夏季7、8月份云冈石窟内室存在水汽凝结的条件,单个凝结期可以持续数小时乃至数日。凝结期吸湿速率比非凝结期大0.017～0.054mm/h。窟内水汽环境变化与山体水汽环境的变化存在着相互作用。钻孔监测表明山体包气带基本处于水汽饱和状态,深部气温稳定在9～10℃之间,存在驱动空气对流的气压梯度。

Condensation of vapor is one of the sources of liquid water on the rock face in Yungang Grottoes.It is a significant work for protection of the culture relics in the grottoes to investigate the watervapor transfer processes and the variation characteristics of water-vapor environment in the rock hill.In this presentation the principle of water-vapor transfer is reviewed and a condensation water monitoring method is proposed.This method has been combined with an observation system in the 5th and 9th grottoes.It is indicated that on July and August the air conditions are satisfied for vapor condensation occur.A condensation period can be several hours or days and during the period the moisture adsorption rate can be 0.017 ～ 0.054mm / h higher than that in non-condensation period.Interactions of water-vapor environment between grottoes and the rock hill exist.The boreholes observation show that almost the whole vadose zone in the hill contains vapor-saturated air and in deep the temperature is steady between 9 ～ 10℃ with airpressure gradient which can drive air flow.