Anhui Provincial Urban Construction Design & Research Institute (China)

Abstract Accurate mapping of complex terrain is very important in the fields of geological disaster monitoring and smart city construction.However, traditional surveying and mapping methods are inefficient, costly and have incomplete data coverage in complex scenes.In this paper, a high-precision mapping method of complex terrain is proposed, which combines Unmanned Aerial Vehicle (UAV) remote sensing and 3D laser scanning.Through the collaborative observation scheme of "wide area coverage in the air+ground detail enhancement", combined with deep learning assisted point cloud registration and noise filtering technology, the measurement of plane accuracy 5cm and elevation accuracy 3cm has been achieved.In addition, the terrain adaptive filtering algorithm developed by the research has improved the completeness rate of extracting surface information from vegetation covered areas to over 90%.The effectiveness and universality of the method have been verified in typical scenarios, providing a new technical solution for high-precision mapping of complex terrains.

In the past few decades, solidification/stabilization (S/S) technology has been put forward for the purpose of improving soil strength and inhibiting contaminant migration in the remediation of heavy metal-contaminated sites. Cement, lime, and fly ash are among the most common and effective binders to treat contaminated soils. During S/S processing, the main interactions that are responsible for improving the soil's behaviors can be summarized as gelification, self-hardening, and aggregation. Currently, precipitation, incorporation, and substitution have been commonly accepted as the predominant immobilization mechanisms for heavy metal ions and have been directly verified by some micro-testing techniques. While replacement of Ca2+/Si4+ in the cementitious products and physical encapsulation remain controversial, which is proposed dependent on the indirect results. Lead and zinc can retard both the initial and final setting times of cement hydration, while chromium can accelerate the initial cement hydration. Though cadmium can shorten the initial setting time, further cement hydration will be inhibited. While for mercury, the interference impact is closely associated with its adapted anion. It should be pointed out that obtaining a better understanding of the remediation mechanism involved in S/S processing will contribute to facilitating technical improvement, further extension, and application.