RESUMO
This study, using Jinan as a case study, systematically investigates the characteristics and geological genesis of loess-like silty clay in the middle and lower reaches of the Yellow River. The primary distribution of loess-like silty clay is revealed through field surveys, laboratory experiments, and previous literature reviews. The chemical and physical properties of the loess-like silty clay were examined, in addition to investigations into its mineral composition, microstructural characteristics, and engineering mechanical properties, in order to enhance comprehension of its attributes and formation mechanisms. The research suggests that the distinctive soil environment in the area has been influenced by numerous instances of the Yellow River overflow and channel shifts over its history, as well as the impacts of climate change, geological factors, and human activities. The primary sources of material for the loess-like silty clay consist of loess, Hipparion Red Clay, and paleosol layers. The discussion also addresses the impact of regional climate on the formation of mineral components. The aforementioned findings hold significant implications for advancing the understanding of historical climatic and paleogeographic shifts, as well as for addressing engineering challenges associated with the distribution of loess-like silty clay.
RESUMO
Jinan is a famous spring city in China. Construction of underground metro system may block groundwater seepage, inducing the depletion risk of springs. This paper presents an assessment of the risk due to metro line construction to groundwater in Jinan City using Analytic Hierarchy Process (AHP) and Geographic International System (GIS). Based on the characteristics of hydrogeology and engineering geology, the assessment model is established from the perspectives of surface index and underground index. The assessment results show that the high and very high risk levels of surface index exceed 98% in the north region; and high and very high risk levels of underground index exceed 56% in urban center and southern region. The assessment result also shows that about 14% of the urban area belongs to very high risk level; regions of high risk are 20% in urban area, 9% in Changqing County and 43% in Pingyin County. In the high risk region, metro lines R1 to R3, which are under construction, and metro lines L1 to L5, which are planned, have very high and high risk. Therefore, risk control measures are proposed to protect the groundwater seepage path to spring.
