基于地气活动的酥碱带形成机制

Mechanism of formation of efflorescence belts based on the earth-air activity

毛管理论不能解释干旱区近地面酥碱带的形成。本工作以敦煌莫高窟的地气研究为基础,通过地气活动规律揭示了酥碱带的形成机制。在大气波动影响下,大气与地气存在频繁的空气交换。当大气压升高时,地气体积压缩,有干燥大气进入土壤。当大气压下降时,潮湿地气膨胀上升,在建筑墙体内到达一定高度。在长期干湿空气的频繁交替作用下,墙体内的大量易溶盐分反复结晶-溶解,导致近地面建筑酥松风化。另外,孔隙内较为剧烈的空气和颗粒物流动对酥松建筑有较强的冲蚀作用。地气导致酥碱带普遍发生,其高度与气压日波动幅度和包气带厚度成正比,与当地大气压成反比。酥碱带地气形成机理的揭示,为建筑酥碱的防治、防潮和土遗址维护等提供了坚实的科学依据。

Capillary water theory cannot explain the formation of efflorescence belts near the ground in arid zones.In this paper,the mechanism of formation of efflorescence belt is revealed based on the earth-air research at Dunhuang Mogao Grottoes.During atmospheric fluctuations,there is frequent air exchange between the atmospheric air and earth-air.When atmospheric pressure rises,the volume of earth-air is compressed,and the dry atmospheric air enters the soil.When atmospheric pressure drops,the damp earth-air is inflated and rises,reaching a certain height in building walls.During long-term and frequent alternation of dry and wet air,a large number of soluble salts in walls crystallize and dissolve repeatedly,causing the degeneration of near-ground buildings.In addition,the relatively intense flow of air and particles within pores has strong erosive effects on buildings.Therefore,it is earth-air that causes efflorescence belts,and the height of a belt is proportional to the amplitude of diurnal fluctuation of atmospheric pressure and the thickness of a vadose zone and is inversely proportional to the local atmospheric pressure.The revelation of the mechanism of formation of efflorescence belts based on earth-air provides a solid scientific basis for the prevention,control and moisture-proofing of building efflorescence belts,and also the maintenance of soil sites.