5. Conclusions This paper summarized the research progress on fine sand performance as raw materials, involving its definition, classification, physical and mechanical properties, as well as dynamic characteristics. Furthermore, various treatment methods for fine sand subgrade are analyzed, including cement treatment, fiber treatment, and other inno-vative materials. Additionally, the application of fine sand in subgrade engineering, specifically focusing on windblown sand subgrade, sand-filled subgrade, and sand blowing subgrade. Ensuring the long-term performance of the subgrade is essential for extending the lifespan of pavement structures. The assurance of subgrade performance spans various stages, including design, construction, and ongoing maintenance. Upon reviewing ex-isting research, several academic and engineering challenges that urgently need reso-lution in the application of fine sand subgrades can be presented. 1. Subgrade evaluation and treatment techniques. The subgrade must possess sufficient bearing capacity, resistance to deformation, and stability to provide a solid foundation for road construction. For fine sand subgrades with specific characteristics, particular attention must be paid to their risk of dynamic instability under seismic or traffic loading. Therefore, scientifically evaluating fine sand subgrades and developing rational treatment techniques are the primary challenges that need to be addressed initially in the construction of fine sand subgrade. 2. Dynamic characteristics of fine sand filler. Due to the unique geographical environment of fine sand, significant differences exist in natural moisture content, capillary rise height, and other aspects. Currently, there is no unified classification method for fine sand fillers, further complicating the wide-spread utilization of fine sand. Therefore, accurately evaluating the suitability of fine sand as a subgrade filler has become one of the key challenges that urgently needs to be addressed. 3. Suitable fine sand subgrade structural system and structural behavior. Fine sand is a loose material with no cohesive force, posing challenges for compaction and vulnerable to erosion by water flow. Therefore, traditional subgrade structural systems are insufficient to ensure the long-term performance of fine sand subgrade. Hence, identifying a subgrade structural system suitable for fine sand fillers and accu-rately analyzing its behavior are critical challenges that must be addressed in the design process of fine sand subgrade. 4. Construction and quality control technology of fine sand subgrade. Analyzing compaction mechanisms in fine sand subgrades and developing con-struction techniques and quality control methods that align with sand core structures are challenging aspects of fine sand construction technology, necessitating thorough research. 5. Diagnosis and treatment technology for fine sand subgrade issues. Traditional diagnostic methods for subgrade issues primarily involve excavation and probing, which are costly, time-consuming, yield excess data, lack precision, and can potentially damage the surveyed route. Traditional diagnostic methods may lead to overall instability of fine sand subgrade due to sand leakage. Therefore, the development of non-destructive detection and identification techniques for defective subgrade is crucial during the operational maintenance phase to ensure the long-term performance of fine sand subgrade. content above is conclusions, I want to split the "Conclusions" chapter to two chapters "Results and discussions" and "Conclusions".

1个月前