Gongcheng Kexue Yu Jishu/Advanced Engineering Science

The experiment focused on the absorption and drainage characteristics of recycled coarse aggregate. The recycled coarse aggregate bonded with strain gauges was embedded in C30 strength grade concrete, and the shrinkage strain of recycled coarse aggregate in concrete during drying shrinkage was measured directly. Based on the relationship between the strain and drainage rate of recycled coarse aggregate under different humidity conditions, the drainage characteristics of recycled coarse aggregate in concrete were calculated, and the relationship between the drainage rate of recycled coarse aggregate and the drainage rate of recycled coarse aggregate was established. The results showed that the trend line of strain and saturation curve of regenerated coarse aggregate was relatively close to that of natural coarse aggregate in the process of draining and drainage, and the strain variation caused by dry and wet of the two kinds of aggregate had a reversible trend. There was a linear relationship between the strain and the drainage rate of recycled coarse aggregate and natural aggregate. The shrinkage strain of coarse aggregate in concrete was smaller than that of specimen, and the shrinkage strains of recycled coarse aggregate and recycled concrete were larger than that of natural aggregate and concrete. The drainage rate of recycled concrete was higher than that of internal recycled coarse aggregate.

Infiltration and groundwater have been widely considered as the main factors that cause shallow landslides; however, the effect of runoff has received less attention. In this study, an in-house physical-process-based shallow landslide model is developed to demonstrate the influence of runoff. The model is controlled by coupling the shallow water equation (dynamic) and Richards’ equation. An infinite slope stability analysis is applied to evaluate the possibility of regional landslides. A real, small catchment topography is adopted as a demonstration example. The simulation illustrates the variations of runoff and the factor of safety (FS) during a storm. The results indicate that, after the surface becomes saturated, the FS may keep varying due to the increasing pressure head, which is caused by increasing surface water depth. This phenomenon most likely occurs downstream where the slopes easily accumulate water. The depth of the surface water may also be a factor of slope failure. Therefore, it is essential to increase the accuracy of calculating the runoff depth when assessing regional shallow landslides.

The erodibility parameters of barrier dam were an important basis for the evaluation of the outburst flood in the emergency treatment of the dammed lake. The erosion rate was typically modeled with excess shear stress model and Wilson model. However, there is no unified understanding of the range of erodibility parameters. In order to study the range of erodibility parameters of various types of soils and the relationship between the erodibility parameters of two models and soil properties, quickly determine the erodibility parameters of the dam, a database of 279 test results were collected from the literature review as well as by contacting researchers and organizations working on erosion around the world. The samples were classified into coarse-grained and fine-grained soils according to the unified soil classification system. Correlation analysis and regression analysis of the data were used to obtain the relationship between the erodibility parameters and soil properties. Four measures were used to evaluate the statistical significance of the relationship between erodibility parameters and soil parameters for coarse-grained and fine-grained soils: R2、MSE、Fvalue/Fstatistic and cross-validation. The erodibility parameters obtained from the experimental data were compared with the erodibility parameters predicted by the regression equation, the range of erodibility parameters of different soil and correlation between erosion parameters and soil parameters were obtained. According to the erodibility parameters database, the regression equation of erodibility parameters were obtained through statistical analysis of limited soil parameters and erodibility parameters to quickly predict the erosion rate of the soil. Finally, taking Baige weir plug as an example, according to the erodibility parameter database and statistical relationship established in this study, the erodibility parameters and erosion rate were analyzed rapidly. The research findings can be used to quickly determine the erosion parameters of the dam plug body, and provide help for rapid assessment of the risk of burst flood under emergency conditions.

The Batang—Mangkang section of the G4218 highway is located in the transition zone from the Jinsha River Valley to the plateau, and facing with strong neotectonic activities, broken rock masses and frequent geological disasters. Therefore, the construction and maintenance of the highway in this region are of huge difficulties. Traditional ground geological survey methods face many difficulties in highway route selection, disaster assessment and stability analysis, etc. Combining the optical remote sensing interpretation of geological hazard points with deformation observation by InSAR technology, it is expected that the geological hazard points in this region can be investigated quickly, accurately and efficiently, and reveal their development and distribution rules of geological disaster points.Under the special geological conditions of the high mountains and valleys of the Qinghai–Tibet Plateau, the common types of geological disasters in the region were summarized, and the method of integrated highway remote sensing identification was put forward based on the study of the characteristics of regional disasters and remote sensing technology. Using this method, we carried out disaster surveys on the Batang—Mangkang section, with full knowledge of optical remote sensing visual interpretation technology and InSAR technology, supplemented by field geological survey, GIS spatial analysis, engineering geological analogy , etc. The conclusions of this article are as follows: 1) A total of 670 geological disasters were interpreted by optical visual remote sensing in the study area,and InSAR technology combined with four kinds of SAR data interpreted 220 active geological disasters; 2) The development rules of different types of geological disasters in the study area varied greatly with the change of topographic features, geological conditions and geological disasters and other influencing factors. There were differences in spatial distribution and formation lithology of geologic hazard using the optical remote sensing or InSAR technology; 3) According to the comparative analysis based on the field work, it was concluded that the interpretation results of optical remote sensing and InSAR had a certain relationship with the interpretation methods, imaging conditions of the images and the activity of landslide. The two methods cannot be used for mutual inspection directly;4) The use of comprehensive remote sensing technology was universal in the highway construction of the high mountain valley of the Qinghai–Tibet Plateau. It made full use of the complementarity of optical remote sensing interpretation technology and InSAR deformation observation technology. On the basis of saving time and cost, this method can have a more comprehensive and accurate understanding of the development of regional geological disasters.

The mountain flood disaster is one of the major natural disasters in the world. The global economic loss caused by flash floods in the 21st century has reached more than 46 billion US dollars per year. The area of mountain flood disaster prevention and control accounts for about 40% of the land in China, whereas the fatality caused by mountain flash floods account for approximately 70% of the death toll from flood disasters. In recent years, the construction of mountain torrent disaster prevention and control projects have been carried out in an all-round way in China. A mountain torrent disaster prevention and control system combining specialists and groups has been basically established, and the technical level of mountain torrent disaster monitoring and early warning has been significantly improved. Examples of torrential rain and flash flood disasters show that the flash flood disasters with heavy casualties and property losses often result from the combined effects of flood and sediment. In the past, scientists mostly paid attention to the flood's role while ignoring that the combined effect of flood and sediment would significantly increase the risk of mountain torrent disasters. To further improve the ability to prevent and control mountain flood disasters, it is urgent to study the critical technologies of flood and sediment disaster forecasting and early warning. The project “Research and Demonstration of Key Technologies for Forecasting and Early Warning of Flash Flood and Sediment Disasters in Mountainous Rainstorms” focuses on the joint action of flood and sediment and condenses four critical scientific and technological issues: 1) mutation mechanism of runoff and sediment yield and disaster-causing coupling mechanism of the flood-sediment process and gully-bed drastic change in mountainous area under heavy rain; 2) early identification of flood and sediment disasters and integrated intelligent monitoring technology for disaster-causing elements in mountainous rainstorms; 3) simulation and rapid prediction technology of flash flood and sediment movement process in a mountainous rainstorm; and 4) disaster risk dynamic assessment and early warning and prevention technology based on the dynamic process of mountain flood and sediment disaster. Focusing on the connotation of critical scientific and technological issues, we proposed five key research contents including 1) study on the process of runoff and sediment production in mountainous areas and the disaster mechanism of flood and sediment coupling; 2) early identification and intelligent monitoring technology for flood and sediment disasters in mountainous areas; 3) simulation and rapid prediction technology of flood and sediment movement process in a mountainous rainstorm; 4) dynamic assessment and early warning technology of flood and sediment disaster risk in mountainous areas; 5) construction and demonstration of a platform for forecasting, early warning, and prevention of flood and sediment disasters in mountainous areas. The research results will improve the real-time accuracy and intellectual level of monitoring, early warning, prevention and control of heavy rain and flash flood disasters in China.