Guomao Engineering Design Institute

Abstract. With the acceleration of urbanization, the Chinese government has placed increasing importance on the preservation of historical and cultural sites. Recently, the Beijing municipal government has been working on the World Heritage application for the Beijing Central Axis for several years and has set a clear goal to formally apply for World Heritage status before 2025. Currently, the project has entered the final sprint stage (Zhang Yongjun, 2018(12):105-107).The Beijing Central Axis, as an important carrier of natural and cultural heritage, embodies a unique cultural heritage. As "Beijing's unique and magnificent order," the Central Axis is not just a single line but a corridor. However, during the preparation for the World Heritage application, there have been different understandings of the concept of the Central Axis, and the selection of heritage sites has not been comprehensive and systematic. Therefore, in studying the issues related to the Central Axis, utilizing POI data to conduct kernel density analysis and linear regression analysis on the cultural landmarks within Beijing can help infer the location of the Central Axis in different periods. By employing spatial analysis methods using ArcGIS, a systematic study of the characteristics of the Beijing Central Axis can be conducted, summarizing its distribution and spatial form characteristics across different dynasties. This research can provide valuable reference for future in-depth studies, conservation and utilization efforts, and the World Heritage application of the Central Axis.

N dopants could regulate the electronic structure of carbon matrix, improve the adsorption affinity between carbon surface and PS anions, and thus pose significant effect on the carbon induced PS-AOPs.

Red soil from Guangxi, China was selected as the background soil, and a porous biomorphic genetic composite of α-Fe2O3/Fe3O4/C comprising a bamboo template (PBGC-Fe/C) was used as a passivator to remediate As(Ⅴ) contaminated soils. The performance of PBGC-Fe/C was characterized by Scanning electron microscopy (SEM), X-ray diffraction (XRD), and Fourier-transform infrared spectroscopy (FT-IR). The results showed that PBGC-Fe/C could improve the passivation effect of As(Ⅴ) from the contaminated soils compared with a single passivation material. Under the conditions of a 5% dose addition, 25% water content, and particle size of 100 mesh, the stability rates of PBGC-Fe/C on As(Ⅴ) contaminated soils with different concentrations of 500 mg·kg-1 and 1000 mg·kg-1 could reach 80.95% and 73.49%, respectively. The porous biomorphic genetic composite of bamboo charcoal provided a large number of adsorption sites for As(Ⅴ), and the acidity of the soil was favorable for the remediation of As(Ⅴ) via passivation. Moreover, PBGC-Fe/C could not only adsorb and fix As(Ⅴ), but also promoted the stabilization of As species. Chemical complexation and ion exchange played major roles in this passivation process.

Several weak intercalations of carbonaceous shale, which are commonly developed in the Permian thick limestone strata in Wulong County, Chongqing, southwestern China, form a structure of alternating layers of soft and hard rocks, which control the stability of massive layered rockslides. We focus on the Permian carbonaceous shale and analyse its mineral composition, microstructure and shear creep characteristics during the three evolutionary stages. The analysis results indicate the following: (i) During the evolutionary process of the carbonaceous shale, the microstructure changed from compact to loose, and the clay mineral content gradually increased from less than 5% in the original soft rock to 5–10% in the interlayer shear zone, and finally to greater than 10% in the sliding zone. (ii) Under the identical shear stress, the creep displacement and rate gradually increase nonlinearly. Under the identical normal stress, the long-term shear strength gradually decreases, and the drop in cohesion is greater than the internal friction angle. (iii) We established an improved Burgers nonlinear damage creep model, which fully reflected the creep deformation process of the carbonaceous shale. The fitting curve of the model matched the experimental results well.