Abstract: The fill soil is characterized as having complex sources of composition, heterogeneous engineering properties, potential collapsibility, high compressibility and low shear strength. The engineering properties of fill soils are rarely investigated and there are no code recommendations available regarding the projects on fill soils. As a result, the unimproved fill soil cannot be directly used as the bearing soils for the engineering structures and facilities. This paper presents the results of geotechnical testing results from a fill soil site in Guilin. The geotechnical properties of the fill soil were investigated throughout the laboratory and insitu tests and the settlement of the fill soil under the surcharge soil load was predicted. The following results are obtained: in general, soil at shallow deposition is less compacted than that of at deeper depth; the tested compression indices are less than 0.2, which means that the fill soil at the site has low compressibility. After 1.5 years of surcharge, the test results on samples taken from depths between 4.2 and 6.45 meters indicate that the samples are close to the normally consolidated state. The observed settlement value at the site consistent with the predicted degree of consolidation. There is no unified and simple engineering way of reusing the fill soils due to their sources of composition and different in methods of backfills.

Key words: fill soils, laboratory tests, degree of consolidation, in-situ soil tests