The study on engineering characteristics and compression mechanisms of typical historical earthen site soil

Abstract

Abstract Soil, as an important building material, has been widely used for a long time. Earthen sites are representative ancient buildings made of rammed soil. As significant archives of human history, culture, and architecture, earthen sites are seriously deteriorated by age, poor conservation, and exposure to the environment. Therefore, the restoration and protection of earthen sites are necessary and urgent. Northwest China has a long history and the earthen sites in this area are widely distributed, numerous and highly valuable. In order to understand the characteristics of the earthen site, a typical site in this area is taken as a case to test the physical, mechanical, and environmental durability of the site soil. The site soil is silt; it is low in the liquid limit and plastic limit, the particle size distribution is good, the material is uniform and compact, the density and strength are extremely high, and the environmental durability is excellent. In view of the problems existing in the earthen site restoration, such as over-reliance on chemical methods, risk of causing new damage and poor similarity after restoration, this paper proposes that the earthen sites should be restored with the material and technology which are similar to the original site. In order to make the restoration material as close to the original site as possible, the soil near the site is selected and particle size distribution is optimized. By changing the variable factors in compaction test, namely hammer weight, hammer blow number, and the drop distance, the compaction mechanism of the site soil is tested; the influence of different compaction factors on maximum dry density is revealed; and a compaction influence parameter λ is introduced to evaluate the influence of compaction factors on the maximum dry density. Contrast test shows that by selecting similar materials and techniques, the maximum dry density and other engineering properties obtained from the compaction test are close to the original site soil. The comprehensive performance of the compacted sample is much better than lime soil which is usually used to restore earthen sites. This result shows that it is feasible to select nearby materials and original techniques so as to make restoration site more similar to original site. The findings in this paper can provide reference for better restoration of earthen sites.