Numerical Analysis The Subgrade Deformation Of Subgrade Widening Based On FLAC^3D

In recent years, with the rapid development of economy, the traffic volumes of expressway are rapidly increasing. A considerable number of expressways in service no longer satisfy the need for both increasing traffic volumes and social progress, and service level is significantly decreased. Therefore, accelerating the upgrading of the road network and expanding the capacity of major roads become very urgent. It is foreseeable that widening project of the road within a decade will be an important topic that highway construction in our country need to be addressed and solved urgently.This paper focuses on deformation differences and other issues turned up in the process of expanding new and existing subgrade. For example, based on the widening project of Luohe section of National Highway 107, research on the features of interaction between the new and existing subgrade of widening project is being carried up systematically, analyzed the settlement between new and existing embankments, lateral displacement and differential settlement by the means of investigation and evaluation of the project site, numerical simulation of finite differential method and theoretical analysis.On this basis, the construction technology of the widening highway roadbed is discussed. The main work and conclusions can be given as follows.(1) By establishing widening subgrade numerical model by FLAC3D, characteristics of the interaction between new widening and existing subgrade is analyzed, including studying not only the deformation behavior and influencing factors of the interaction between widening and existing subgrade during step loading on new roadbed but also the impact of filling weight, height, width, modulus and other material properties of filling on deformation of widening roadbed. Calculations show that the way of widening subgrade, the material properties of the new roadbed and so on have an important effect on engineering characteristics and the interaction between the new existing roadbed and the old roadbed.(2) By use of geogrid structural units in FLAC3D, the measure of laying geogrid units at the joints is taken to simulate and analyze inhibition of deformation and differential settlement between the new and existing roadbed, and the regular pattern of influencing its roadbed deformation and differential settlement is researched from the laying of different geogrid ways and other factors such as modulus.The results find that it is using the bottom of the single embankment paved with geogrid that make economic efficiency and reinforcement effect optimized; the greater the geogrid modulus, the better optimization effect of differential settlement of widening subgrade. Calculation results of the analysis provide a theoretical basis on the number of geogrid layers and the way how to lay geogrid at the joints between the new and existing roadbed.