Improvement Expeirment And Subgrade Settlement Control Of The Reservoir Area High Liquid Clay

High liquid limit clay is a kind of bad nature of soil, which is a very common situation in the southern rainy area of China. Filling subgrade of reservoir with high liquid limit clay is one of the common technical problems in the process of highway construction. High liquid limit clay is characterized with high porosity, poor consolidation, poor permeability and high water sensitivity etc,its soil compression strength change great, stable subsidence of subgrade becomes larger and stability of subgrade reduces under the action of water. Study on improvement experiment and subgrade settlement control of the reservoir area high liquid clay is important to stability of subgrade.Based on renovation project of connecting line named Shui Fumiao of highway from Xiangtan to Shaoyang, soil samples have been taken back from scene after the engineering geological investigation in this paper. Improved indoor tests were taken to research the lime and T.O.P modifier modified mechanism which indicated that the results were good; economic and technical comparison with different improvement programs has been done which resulted in a filling scheme about subgrade of reservoir with high liquid limit clay. Wetting-drying effect of the reservoir water causes the strength of high liquid limit clay decays substantially. Mechanical properties indoor tests with independent researched direct shear apparatus have been done to study the attenuation laws of shear strength and compression strength of high liquid limit clay under wetting and drying cycles. Comparing with the compression characteristic of lime improved soil and undisturbed soil so as to study the influence of compression performance of high liquid limit clay caused by lime improved.Larger subgrade settlement produced and subgrade stability reduced under wetting and drying cycles. A cross-section of Private Dam Reservoir has been selected as a case to embed settlement plates for field settlement observations and construction quality control of subgrade in this paper. Based on the data of field settlement observations, the unequal time-interval gray forecast model has been used to forecast the settlement of subgrade. Comparing with predicted values and measured values of settlement and then carry through precise check up, the forecast veracity of unequal time-interval gray forecast model for subgrade settlement of reservoir with high liquid limit clay has been verified. The forecast about settlement of subgrade after completion of filling which help us make sure the stable phase and the construction time of surface course. The construction technology of subgrade with improved high liquid limit clay will be controlled so as to control the quality of subgrade filling.The research results in this paper are directly applicable to the renovation project of connecting line named Shui Fumiao of highway from Xiangtan to Shaoyang. It provide references for the study of construction control of subgrade with similar situations by improvement experiment and subgrade settlement control.