中国西北地区气象因子对夯土遗址裂隙发育的影响

中国西北地区遗存有大量的土遗址，其种类繁多，形式各异，时刻遭受各类气象因子的影响，裂隙是其普遍发育的病害之一。为了更好地研究气象因子对夯土遗址裂隙发育的影响，本文基于近5a对分布于甘肃和青海境内的多处明代夯土遗址开展的工程实践，分析了降雨、蒸发、温度、日温差和日照等主要气象要素对裂隙发育的影响，较好地揭示了我国西北地区夯土遗址裂隙发育的气象环境效应。分析结果表明：（1）随着降雨量的增大，蒸发量的减小（即干旱指数的减小），温度的降低和日照的减弱，裂隙发育率、平均裂隙长度和最大裂隙长度整体趋于增大，且相对潮湿的自然环境更能促进宽大裂隙的后期发育；（2）随着降雨量的减小，蒸发量的增大（即干旱指数的增大），温度的升高和日照的增强，平均裂隙宽度和最大裂隙宽度整体趋于增大，且干旱状态的自然环境更能促进微小裂隙的前期发育；（3）气象环境对遗址的影响是一个复杂的过程，影响的因素较多，且往往是同时进行、相互影响和相互促进的，其对土遗址所产生的影响结果是相似的。

DEPENDENCE OF THE FISSURES IN THE ANCIENT RAMMED-EARTHEN SITES ON THE METEOROLOGICAL FACTORS OF THE NORTHWESTERN OF CHINA

Earthen structures, one of the most earliest architectural style, are widely distributed all around the world. There are lots of earthen heritage sites that still remain in northwest of China. The variety of earthen structures ranges from simple forms to vast, and the construction techniques varies from culture to culture and region to region. However, the majority of historic buildings and archaeological sites made of earth exhibit serious conservation problems due to various environmental conditions. Among these styles of deteriorations, fissure is one of the most common and widely developed diseases on earthen sites, which has a great influence on structural stability of sites. According to the in-situ engineering data obtained in recent 5 years, from the ancient rammed-earth ruins in Gansu and Qinghai provinces, which can date back to Ming-Dynasties, this paper analyzes the influence of primary meteorological factors, i.e.rainfall, evaporation, temperature, daily temperature difference and sunshine, on the development of fissures in the rammed-earth sites. The results of this study well reveal the meteorological environment effects on the development of fissures. The analytical data shows that the fissures in the ancient rammed-earth ruins suffer different actions of the meteorological factors in the northwestern of China, such as rainfall, evaporation, temperature and sunshine etc. The main conclusions are as follows:(1) the average fissure length and maximum fissure length tend to increase with the increasing of rainfall, decreasing of evaporation, reducing of temperature and decreasing of sunshine; however, the fissures have a tendency to expand in humidity environment.(2) the average fissure width and maximum fissure width tend to increase with the decreasing of rainfall, increasing of evaporation, increasing of temperature and sunshine; meanwhile, the arid environment can have a positive effect on the development of tiny fissures in the early stage.(3) the impact of the meteorological environment on the sites is a complex process. The factors are various and have a mutual influence which promotes each other. As a result, the impacts of these meteorological factors on earthen sites are similar.