【作者】 白贵斌；

【导师】 张虎元；

【作者基本信息】 兰州大学 ， 建筑与土木工程， 2012， 硕士

【摘要】 甘肃凉州明长城属于夯土长城。在长期的风化作用下,其外貌形态发生了较大的变化,诸如剥离、冲沟、坑洞、裂隙、掏蚀以及坍塌等各类病害均有不同程度的发育,加上近年来工业化对环境的影响,使长城的保存受到了挑战。土遗址相关工作人员研究了土遗址的病害类型及形成机理、加固方法、有机及无机等加固材料、各种检测方法等,并取得了一定的成就。但是,对土遗址有影响作用的生物研究相对较少。本研究以“甘肃凉州境内长城、烽燧遗址抢险加固工程”为背景,研究了凉州明长城的保存现状、病害类型以及苔藓及地衣对长城土遗址体的作用。在对凉州明长城做现场勘察后发现其大致分东西方向和南北方向两部分。南北方向长城墙体保存现状差,长城断断续续,残缺不全,有墙体存在的地段大部分被风沙掩埋,墙体东西两面各类病害均较发育,尤其以掏蚀、坍塌、冲沟及剥离为严重。东西方向长城墙体保存较南北方向好,长城基本连续,无风沙掩埋,墙体南面病害发育,主要病害为掏蚀、坍塌、冲沟及剥离等；墙体北面有大面积苔藓及地衣覆盖,形成苔藓结皮及地衣结皮,病害发育较轻,主要病害为墙体底部的掏蚀及剥离。经过对比有无苔藓及地衣覆盖墙体的病害发育状况后得出苔藓及地衣对长城墙体有保护作用。对苔藓结皮及地衣结皮展开研究可以揭示苔藓及地衣对长城遗址土体的作用机理,从而揭示苔藓及地衣对长城土遗址体的作用。选取东西向长城墙体北面苔藓结皮及地衣结皮试样、南面非结皮试样。对所取苔藓结皮、地衣结皮及非结皮试样进行扫描电镜,化学分析,颗粒分析,X射线衍射等试验。分析试验结果并得到以下结论：(1)通过对比苔藓结皮、地衣结皮以及非结皮试样表面电镜照片可以得到：苔藓和地衣在长城墙体表面与土体共同形成一个结构面。此结构面土颗粒较小,颗粒间孔隙被苔藓及地衣或其生成物所填充,因而较为密实,能有效的防止风、雨等因素对墙体造成的破坏。(2)化学分析试验表明：苔藓和地衣选择性的吸收了长城遗址土体中的易溶盐离子。苔藓及地衣对土中离子的吸收特别是对钠离子等的吸收,使土体中易溶盐如硫酸钠等的含量大大减小,从而减小了易溶盐的表面富集作用,降低了易溶盐因反复结晶而对长城墙体造成的破坏。(3)颗粒分析试验结果表明苔藓和地衣对长城墙体表面土体有一定的改造作用：使土体颗粒减小,形成一个小颗粒的结构层。这能有效的加强遗址表面土体的粘结性,加强遗址体的抗风化作用。(4)苔藓和地衣在长城墙体表面与土体形成的较为密实的结构面与结构层共同组成遗址体表面的抗风化系统一苔藓结皮和地衣结皮,有效的减小了长城墙体各种病害的发生和发育。更多还原

【Abstract】 The Ming Great Wall in Liangzhou district Gansu province belongs to ramming Great Wall. It’s Appearance shape has changed greatly in the long-term weathering, such as stripping, gullying, hollowing, fissuring, sapping and sloughing disease are in the different developmental condition, and it was thanks to the industrialization of the impact on the environment in recent years that the preservation of the Great Wall has been challenged. Soil sites staff have researched the disease types and forming mechanism, strengthening methods, organic and inorganic and other reinforcing materials, all kinds of test method, and so on. Of course, they got some achievements in their work. But, the research about influence to soil sites from some other biology is very little. Under the background of "rescue reinforcement engineering of Great Wall and beacons in Liangzhou district. Gansu province", The research studied the save situation and the type of disease of the Great Wall, and the influence from bryophytes and lichens to the Great Wall.After the site investigation to the Great Wall of Ming, we found that the Great Walls were constituted by two sections, north-south direction and east-west direction. The north-south direction’s present situation was bad. The Great Wall was discontinuous and incomplete, some existing wall was buried by blown sand. All kinds of diseases, such as sapping, sloughing, stripping and gullying, had developped in both sides of the wall. The east-west direction’s present situation was better than the north-south direction. The Great Wall was continuous and not was buried by blown sand. Diseases, especially sapping, sloughing, stripping and gullying, had developed in the south side of the wall. The north side was covered by bryophytes and lichen, it had formed bryophytes crust and lichen crust. The major diseases were sapping and stripping in the bottom of the wall. Through comparing the diseases’development state of the walls that were covered by bryophytes and lichen or not we knew that the bryophytes and lichen were beneficial to protect the Great Wall.It revealed the mechanism of the bryophytes and lichen’s effect to the Great Wall when we studied bryophytes crust and lichen crust. Selected bryophytes crust and lichen crust specimen from the north side of the east-west direction, and selected no-crust specimen from the south side, and then we did the experiment as follows:particle analysis, chemical analysis, scanning electron microscopy and X-ray diffraction. The results showed the conclusions as follows:(1) Contrasted the surface electron microscopy image of the bryophytes crust, lichen crust and no-crust specimen we knew, bryophytes and lichen formed a structural plane together with soil of the Great Wall. Soil particles of the structural plane were less, pores between soil particles were filled by bryophytes or lichen or their secretions. So the structural plane effectively prevent the destruction from wind and rain because it was relatively dense.(2) Chemical analysis test showed that bryophytes and lichen selectively absorbed soluble salt that hosted in soil. Bryophytes and lichen The process decreased ions in soil, especially sodium ion,it leaded to decreasing the content of the sodium sulfate. So it stopped or retarded the enrichment of the soluble salt and decreased the destruction caused by repeated crystallization.(3) Particle analysis test showed that bryophytes and lichen had transformation effect to the Great Wall’s soil. It made soil particles become small and formed a structure layer. The cohesiveness of the soil and the anti-weathering ability of the soil site had been strengthened.(4) Both of the structural plane and the structure layer formed the system of resistance to weathering. The system effectively decreased the occurrence and development of the various diseases.更多还原