Experiment of CBR value of loess subgrade improved with quick lime and its application

The California bearing ratio(CBR value) of subgrade filling material reflects the capacity to resist the local shear in the soil,and was one of the major indexes to evaluate the strength and stability of the subgrade soil.Taking the loess located at Dingxi area in Luoding highway as investigation object,CBR tests were conducted in cases of different compaction times,lime dosages and immersion times.The test result indicated that the strength and water stability of the microscopic structure of the loess would be obviously improved due to the inclusion quick lime.Compaction degree of lime soil would be lower than that of loess with the same compaction times;CBR would reach its maximum value when compacted by 70 times;in laboratory the optimal lime dosages in loess was equal to 3%.A linear regression relation among lime dosage,compaction degree and CBR was put forward and was verified and applied in six test sections of Luoding and Baotian highways.