Study On Differential Settlement And Reliability Of Soft Foundation Treatment In Road Widening Project

Road widening is one of the common solutions to the traffic volume’s rapid growth ofhighway. The problems of road widending are more complex than new-bulit road’s, such as thesettlement of widened subgrade, the effect of new load on the original road, the differentialsettlement of the widened and original subgrade(especially for the soft soil subgrade), thedeformation of pavement, which should be solved urgently. In this paper, the differentialsettlement of new and original subgrade is analysed, and the main contents are as follows:1. The differential settlement control is studied from the aspects of design, construction anduse, and the control standard of differential settlement in the soft soil section of road widening isobtained. The differential settlement should be limited to0.04m considering the comfortablenessof users, and the differential settlement should be limited to0.07m considering the utilizationrequirement.e.2. Relying on the project examples, the loading of different stage in road widening isnumerically simulated, and the results are proved by the obtained observation data.3. According to the different characteristics of different treatment methods of soft soilsubgrade, the treatment effect of different treatment metheods under different angles isnumerical simulated using total and differential settlement as evaluation standard. The fillingmaterial of EPS is more effective than other light filling materials in reducing the filling load;condering the integrity and strength of subgrade in road widening, the size of slope cutting haslittle influence on the total settlement and effective stress, while greater influence on differentialsettlement of the joint of widened and orignal subgrade, which need the treatment methods suchas step excavation and earthwork synthetic material to increase the contacting area betweenwidened and orignal subgrade; considering improving the foundation bearing capacity,increacing the degree of consolidation and composite foundation method can effectively solveboth subgrade and differential settlement problemes in road widening.4. The reliability of strengthened soft soil subgrade in widening road is analysed accroding tothe numerical simulation depending on the characteristics of road widening. And the results show that the strengthened soft soil subgrade can meet the engineering utilization requirement.