Young loess deposits are the most well-known collapsible soils because of their small unit masses, high void ratios, and open metastable structures. Properly assessing the collapse of loess sites covered by very thick interbedded loess–paleosol strata is complicated because the loess and paleosol layers possess significantly different permeability and collapsibility. The Tongchuan Loess Tableland is one site of such strata, and for this research, laboratory and field tests were conducted to obtain the physical and mechanical properties of the soil for each of the loess and paleosol layers. An in situ soaking test and corresponding computation were also conducted to explore the soaking process, seepage field, and collapse settlement characteristics of the site. Significant differences in collapse settlements were observed between the in situ soaking test and the computed result. The authors deduced that the strata of the test site, disturbances during extraction, drainage conditions, stress history, loading conditions, sampling interval, and magnitude of the collapse criteria could have been the reasons for the differences.