Abstract: In order to find out an effective and practical approach to reduce the settlement and increase the strength of an approach embankment filled with loess so as to avoid the bump at bridgehead, the methods were suggested by mixing a proportion of sand into the loess or reinforcing the loess with geogrid, or by using these two skills together. For examining essentially the feasibility of these ideas, the deformation and strength properties of geogrid-reinforced loess, loess mixed with sand (LMS) and geogrid-reinforced LMS were investigated in laboratory. A series of resilient modulus tests and unconfined compression tests were conducted respectively using samples made up of LMS or pure loess either with or without geogrid-inclusions. Each sample varied either in the number of reinforcement layers from 0 to 5, or in the degrees of compaction of 88%, 92% or 96%. Based on a detail analysis of the test results, the following conclusions are drawn: (1) The resilient modulus of the loess increases significantly either by mixed with sand or by reinforced with geogrid. More improvement is demonstrated while the both methods are applied together in a loess sample. (2) The compressive strength of LMS is much greater than that of loess when the LMS and the loess both are either with or without geogrid inclusions, especially under small compressive strain. (3) The compressive stress-strain pattern of a geogrid-reinforced LMS changes gradually from strain-softening to strain-hardening either while the geogrid layers increase at a certain degree of compaction or when the degree of compaction decreases at a given geogrid layers. (4) There is an appropriate strength match between the geogrid and the LMS, according to which a geogrid-reinforced LMS with higher density is suggested to be reinforced with smaller reinforcement spacing so as to obtain a maximum strength derived from a compatible deforming between the geogrid and the soil.

Key words: loess mixed with sand, geogrid-reinforcement, resilient modulus, unconfined compression, laboratory test