Exploring the paleoclimatic influence on the physico-mechanical properties of a loess-paleosol sequence in the sandy loess belt of China

Research on Quaternary climate change has the potential to shed further light on the change patterns of the physico-mechanical properties of loess-paleosol sequences (LPS) in the context of engineering and construction activities. In this study, the physico-mechanical properties of a well-preserved and continuously deposited LPS in the sandy loess belt of China were investigated. Paleoclimate change was inferred using a series of climate proxies including grain size, geochemical elements, and magnetic susceptibility. The results showed that multiple alternating climate change events in the Middle to Late Quaternary were recorded as vertical variations in the physico-mechanical properties. The void ratio, plastic limit, compression coefficient, internal friction angle, and collapsibility coefficient of the loess layers were associated with weak pedogenic weathering under cold/dry paleoclimate conditions in glacial stages. On the contrary, paleosol layers developed with strong pedogenic weathering under warm/humid climates during interglacial stages, leading to higher natural moisture content, saturation, liquid and plastic index, compression modulus, and cohesion. The combined application of physicomechanical properties and climate proxies can help in improving our understanding of the evolution of the physico-mechanical properties of LPS under climate change and promoting geological engineering design.