Direct Shear Test On Cement-Modified Sandy Silt At Negative Temperature

The most common diseases of pavement in seasonal frost area are frost heaving, which leads to frost boiling are the main reason for the reduction of the shear strength. So relevant measures must be taken for the purpose of improving the shear strength of pavement soil in cold regions. The research of this article is one part of the western development of transportation technology projects "the mechanism and preven-tion of frost heaving and frost boiling in western region under dynamic load". The soil of State Road 109 which heavily damaged by frost heaving and frost boiling in Qinghai Province has been taken as the study object. Previous work like field investigation pro-vide the reason of frost heaving and frost boiling, and also the influence factors, then obtain the cement modified soil method. Based on a series of laboratory tests, and the shear strength of the cement modified soil subjected to relevant influence factors were analyzed to offer the blending details of cement modified soil.This paper summarizes the achievement and present study situation in cement modified soil, which are important for us to study the shear strength of cement modified soil in seasonal frost area in theoretically.In order to study the frost heaving properties of soil, based on the frost heaving test under static load in cooling temperature laboratory, the influence of frost heaving char-acteristics by water content,closed system or open system,cement blending ratio has been studied.The direct shear test of cement modified soil in cooling temperature laboratory in-vestigates water content,cement blending ratio,cooling temperature and curing time, which have great impact on the shear strength of cement modified soil.