Cyclic Variability in Chemical Composition and Swelling-Shrinkage Properties of the Xiashu Loess Stratum near Nanjing, China

Xiashu loess strata are widely distributed along the middle-lower reaches of the Yangtze River in East China with the stratum near Nanjing, Jiangsu Province being typical. The cyclic variability of the stratum was investigated through comparison of geological features, chemical composition, and swelling-shrinkage properties between the loess and the paleosol layers. Based on the investigation of such a cyclic variability, soil behavior associated with the unsaturated state of the Xiashu loess stratum and its usefulness for geotechnical design and construction in the Nanjing area was analyzed. The stratum consisted of two types of cyclically alternating soil layers, namely the loess and the paleosol layers, which was the major cause for its cyclic variability. The loess and the paleosol layers were formed in Different sedimentary environments. In order to avoid detrimental results from the Differential engineering properties between them, this study suggested for the practitioners the importance of inspecting the variation of water content and controlling the downward net fluxes during geotechnical construction in the Nanjing area.