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.

Based on the research results and practical engineering experience pertaining to the protection and reinforcement of the cliff of the Mogao Grottoes in Dunhuang, China, this paper presents a method that is mainly based on the analytic hierarchy process (AHP) to evaluate the preservation state and risk of the Mogao cliff, a means that numerical simulation was conducted to quantitatively evaluate the stability and effectiveness of protective measures for the Mogao cliff, a set of reinforcement methods which integrate the key protection techniques based on propping, anchoring, grouting, and anti-weathering and the quality control measures based on assessing their effectiveness for surrounding rocks of the grottoes, and a set of methods for monitoring and warning based on risk theory throughout the entire reinforcement process. The four above-mentioned techniques complement and support with each other, and every stage is based on research. Additionally, the protection and reinforcement concepts implemented at the Mogao cliff are summarized in this paper. Finally, preventive protection and reinforcement techniques for sandy conglomerate grottoes were established based on the research, evaluation, calculation, and monitoring. The techniques presented in this paper can be used as a theoretical foundation and provide technical guidance for the protection and reinforcement of similar cultural heritage sites all over the world.

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.