Study On Failure And Treatment Technology Of Embankment On Slope Foundation Of Expansive Soil

In order to avoid making dangers to the new highway,construction of highways in the western area of expansive soils distributed adopted the way to abandon the used soil and filling the new qualified soil.Even so,many qualified embankment on slope foundation of expansive soil still occurred serious collapse sliding failure after the first rainy season or a few heavy rains which causing traffic disruption,schedule delays and need to invest huge sums of money to repair.In order to clarify the reasons for the occurrence of such problems and propose effective engineering treatment measures,the paper mainly adopts the numerical simulation method to carry out the expansive soil embankment on slope foundation instability and treatment technology research which rely on Qinchong?Bailong?Tanbai highway construction and engineering record.Firstly,we had carried out an investigation for many segment collapse sliding embankment of highway in Guangxi expansive soil area and preliminary determined the main cause of damage.Completed series of indoor soil tests and got basic parameters and indicators of the required analysis and calculation.The numerical model was established which based on Geostudio software and carried out numerical simulation to obtain the variation rule of expansive soil ground and filling pore water pressure,moisture content and embankment safety factor and the most dangerous sliding surface under rainfall conditions.According to internal and external reasons which affect the embankment stability of expansive soil slope foundation,we select five factors which are the shear strength of strong weathered shale in foundation,the original ground cross slope,embankment center filling height,basal replacement gravel layer and groundwater.Made a computational analysis of the specific impact of various factors on the embankment instability and provided a theoretical basis for subgrade design and engineering treatment.Based on analysis results of the factors which affecting the instability of embankment on slope foundation of expansive soil and the existing subgrade specification is lack of effectively process specific provisions of expansive soil foundation.Therefore,to learn from other special soil foundation treatment technology and related engineering experience,try to put forward treatment design and technical measures which make the embankment on slope foundation of expansive soil stable.Treatment technologies are used as follows: excavation of stairs,watertight closure,excavation stairs combined with watertight closure,geogrid reinforced treatment,lime piles and so on.The established numerical models are used to demonstrate the effectiveness of these treatment technologies and put forward four kinds design scheme according to the results.In this paper,the conclusion has some engineering reference value.