Gao Zhiwei

Subgrade moisture content forecast based on probability of precipitation

The correlation between subgrade water content and precipitation in Tacheng and Altay was analyzed, to determine the range of subgrade water content with different precipitation probabilities. According to the statistical analysis of historical data of precipitation, precipitation intervals with different reliabilities were calculated by interval estimation method. Humidity sensors were buried to observed the subgrade water content and precipitation in the same period, then the subgrade water content with different precipitation probabilities were obtained by establishing the functional relationship between subgrade moisture content and precipitation. The results showed that, there was a good correlation between subgrade moisture content and precipitation. The precipitation interval were [14.8,19.6], [15.2,19.2] and [15.4, 19.0] when reliability were 95%, 90%, 85%. The subgrade water content intervals were [3.97,4.31], [4.01,4.28] and [4.02,4.27] with precipitation probability of 95%, 90%, 85%.

Analysis of effect for subgrade settlemen control by centrifuge model test

In order to analyze the effect of differential settlement control measures at the junction of fill and excavation in highway sub-grade, 6 groups of sub-grade centrifugal model experiments were done by centrifugal tester to study the role of steps excavation and laying geogrid at the junction in reducing differential settlement of sub-grade. Experimental results show that the role of steps excavation is small in reducing differential settlement, but laying geogrid can significantly reduce the amount of differential settlement in sub-grade. In centrifuge test model the best laying spacing of geogrid is 2cm ∼ 4cm, after scaling according to the model, in the actual project, controlling geogrid laying spacing in 1m ∼ 2m can effectively reduce the differential settlement at the junction of fill and excavation for highway sub-grade.