STUDY ON CORRELATIONS BETWEEN ELEVATIONS AND DETERIORATIONS IN BEACON TOWERS OF MING GREAT WALL IN QINGHAI PROVINCE

After centuries of wind and rain erosion and man-made destruction, most of Ming Great Wall in Qinghai province have been extinct, and only a few exist as earthen sites. Some related studies indicate that earthen sites of Ming Great Wall have developed 6 types of typical deteriorations including scaling off, gullies, sapping, collapses, cracks, holes and biological deteriorations. As a special architectural type of Great Wall, the beacon tower was responsible for transferring information and because of that military mission, most of them are distributed in high elevation areas. This paper selected 17 beacon towers located in Huangzhong county and the authors conducted the investigation of those on site to collect the deteriorations data. Based on such work and collection of their elevations, it did fitting between those deteriorations statistics and elevations, aiming to acquire the effects of elevations on the development of such deteriorations. According to the system analysis of this work, it concluded that the elevations have influence on biological deteriorations, scaling off, holes and sapping, and have pretty obvious correlations with latter three deteriorations. This study could provide a new strategy for the developmental mechanism of deteriorations in earthen sites, and also supply helpful reference to the protection work for Ming Great Wall in future.