Yumin Du

As a critical component of the Ming Great Wall Military Defense System (M-GWMDS) of Yulin Zhen in Shaanxi Province, China, castle-based military settlements have a horizontal distribution composed of three military routes and a vertical distribution consisting of two defense lines. These settlements played a key role in supervising the defense area and deploying troops. Exploring the spatial and temporal distribution of castle-based military settlements is a key link to revealing the in-depth distribution pattern of the M-GWMDS, but most studies have focused on their macroscopic distribution from a qualitative perspective. In this study, castle-based military settlements were selected as the research objects and were combined with architectural, archaeological, geographic, and military information. Their spatial and temporal analysis, including kernel density, slope/aspect conditions, and river systems, was explored based on GIS tools. By illustrating the military distribution nephogram and introducing the reachable spatial-temporal domains and viewshed, the deployment of military troops in this system was interpreted in depth. Taking both geographical and military factors into consideration, the XTENT model was comprehensively established to quantify the sphere of influence of castle-based military settlements, and the ranking and weights of factors influencing their distribution were eventually determined to illustrate the site catchment of these settlements, revealing the layout characteristics of the Ming Great Wall in the spatial and temporal dimensions to further reflect the military wisdom of the ancients. This research presents a new approach to thoroughly reveal the layout characteristics of the Ming Great Wall from a quantitative perspective, which will be beneficial to their subsequent protection and management.

Since 2006, with the implementation of a series of national research projects in the field of earthen site conservation, the Chinese theoretical foundation and technological conservation system for the protection of earthen sites in arid environments has gradually formed. However, there are some global problems such as an unclear relationship between characteristics of diseases on sites and their existing environment, unclear deterioration mechanisms under multi-field coupling, immature stability control technology under dynamic loading, the poor suitability of protection process quality assessment equipment, and a lack of systematic research on comprehensive protection synergy mechanisms. On the basis of summarizing the research achievements in the field of earthen site conservation in China for more than 30 years, and a large number of practical experiences in earthen site reinforcement engineering, this paper expounds the multi-field coupling characteristics of earthen site construction technology, the climatic environment, and dynamic loading and protection measure activities, clarifies the main characteristics of the protection of earthen sites in China at present, puts forward the key scientific and technical problems existing in the conservation of earthen sites, constructs a picture of the research on the conservation of earthen sites under the action of multi-field coupling, and discusses the protection projects of earthen sites under different environments. We hope the technological system can provide support for the transformation of earthen site conservation from the rescuing conservation stage to the stage of both rescuing and preventive conservation, and move the foundation of earthen site conservation towards the stage of preventive protection.

Having extremely high artistic, scientific and social values, earthen sites are widely distributed in China and are important human cultural relic resources. Due to accumulated natural erosions (from rain and wind) and human activities (destructive activities of human beings in history and modern times), however, earthen sites have been greatly damaged, and many sections have even been absent, so that they are seriously threatened by extinction. Under these circumstances, acquiring the conservation status of earthen sites is a vital prerequisite for the subsequent targeted protection. In this paper, as a world-renowned heritage site, the castles of the Ming Great Wall located in Qinghai Province were selected as the research object. A novel indicator, namely the linear absent section ratio (L-ASR), was proposed, and its value was classified into five levels to quantitatively characterize the specific conservation status of such sites, including excellent (E) (0–10%), good (G) (10–25%), fair (F) (25–50%), poor (P) (50–75%), and very poor (VP) (75–100%). Based on the assessment results, the castles with excellent status constituted the minimum proportion, while the castles with very poor status represented the largest percentage, reflecting the grave situation of earthen sites. Furthermore, by applying population distribution models to the linear fitting combined with the population density (PD), a positive correlation between PD and L-ASR was obtained to reveal the anthropogenic influence on the destruction of earthen sites. Principal component analysis (PCA) was utilized to provide a far richer understanding of which factors correlate most strongly with deterioration. This study provides a new thought to quantitatively characterize the preservation conditions of earthen sites and also indicates the effect of human activities on the damage of earthen sites from a population density perspective, which is potentially used for the analysis of more various types of architecture with different construction techniques. Hence, this approach is beneficial to the overall damage assessment of earthen sites, and also meaningful to their further preservation and protective planning.

Having extremely high artistic, scientific and social values, earthen sites are widely distributed in China, which are important cultural relic resources of mankind. Due to accumulated natural erosions and human activities, however, earthen sites have been greatly damaged and have even vanished many sections, so that they are seriously threatened by extinction. In the circumstances, acquiring the conservation status of earthen sites is a vital prerequisite for the subsequent targeted protection. In this paper, as a world-renowned heritage site, the castles of the Ming Great Wall located in Qinghai Province were selected as the research object. A novel indicator namely the linear vanishing section ratio (L-VSR) was proposed and its value was classified as five levels to quantitatively characterize the specific conservation status of such sites. Based on the assessment results, the castles at the excellent status constituted the minimum proportion, while the castles at the very poor status represented the largest percentage, reflecting the grave situation of earthen sites. Furthermore, applying population distribution models into the linear fitting combined with the population density (PD), the positive correlation between PD and L-VSR was obtained to reveal the anthropogenic influence on the destruction of earthen sites. This study provides a new thought to quantitatively characterize the preservation conditions of earthen sites and also indicates the effect of human activities on the damage of earthen sites from the population perspective. Hence, it is beneficial to the overall damage assessment of earthen sites, and also meaningful to their further preservation and protective planning.

Being a world-renowned heritage site, the Ming Great Wall, located in Qinghai Province, China, mainly has existed as the form of earthen sites with high historical, artistic, and scientific values. However, exposed under environmental impacts for about 500 years, these sites have been seriously threatened. The study on their damage assessment using reasonable methods is the key premise for further protection work. As there are few studies focused on the damage assessment of earthen sites, especially by using machine learning methods, this study explored to apply the current effective machine learning approaches, namely Support Vector Machine (SVM) and back-propagation (BP) Neural Network, into solving this problem. The authors used two such algorithms by training and testing the existing data of damage assessment results of 18 earthen sites located in Qinghai Province. By comparing experimental results, the prediction effects of SVM are much better than those of BP Neural Network. To test its practicability, Liutun Great Wall was chosen as an engineering case, showing better prediction and reasonable performance of SVM. This research has proved that SVM can be selected as a suitable model to assess the damage levels of earthen sites located in Qinghai Province for their future conservation works.

Earthen sites are valuable cultural heritage sites in arid regions of NW China, where a series of serious deteriorations have developed. Scaling off is a typical type of deterioration that greatly threatens the long-term preservation of earthen sites. To date, there are insufficient studies on the formation mechanisms and influence factors of scaling off, leading to a lack of a theoretical foundation for further consolidation research. Therefore, establishing a scientific evaluation system to explore the formation mechanisms of scaling off and assess its degree of development has become a very significant topic for earthen site conservation. In this study, we selected 18 earthen sites to survey scaling off in the field, and data from geotechnical tests and meteorology were then collected to fit the characteristic values to determine the influencing factors. Finally, fuzzy analytic hierarchy process (Fuzzy-AHP) was applied to build a system to evaluate scaling off. The mechanisms of scaling off formation were explained by comparing and analyzing the porosity, shrinkage limit, particle size distribution of rammed earth and environmental factors combined with soluble salt contents in rammed earth. This research reveals the formation mechanisms and influencing factors of scaling off from a new perspective, which will lay a beneficial foundation for further consolidation research.