Abstract:In the process of the roadbed construction of highway engineering in humid and rainy regions in the south of China,the high limit liquid soil is very widely used.The mechanical properties of high liquid limit soil directly affect the long-term stability of the roadbed.Because of the heavy rainfall,it is very difficult to fill the roadbed fill in the actual project, which affects the safety and stability of the roadbed.Therefore,in order to ensure the safety of the roadbed,it is significant to study physical properties of high liquid limit clay and engineering characteristics deeply,especially on the high liquid limit the safety and stability of roadbed.Moreover,there are few studies on the water stability, shear strength index and the change rule of the high liquid limit soil,so it is useful to study the influence factors of the strength of roadbed stability and slope stability In order to study the physical and mechanical properties of the high liquid limit soil of a highway roadbed, the change in mechanical properties of the high liquid limit soil with compaction degree and water content was analyzed by confined compression,rebound,triaxial shear strength tests of soils from two cross sections of the roadbed of a highway,The test results showed that the roadbed soil is moderate compressibility.For the same water content,cohesionc and internal friction angle φ,compression modulusE_s,compression indexC_cincrease with the increase of compaction degree,and rebound index C_sincreases slightly with the increase of compaction degree.For the same compaction degree,the soil samples that their water content are greater than the optimum water content are tested.The compression modulus E_s,compression indexC_cand rebound index C_sncrease with the increase of water content,cohesion c decrease with the increase of water content,the internal friction angle φhardly changes when the water content increases.