Research On The Deformation Features Of Widening Of Highway On Soft Ground

Widening of highway on soft ground is a new challenge in the construction of highway and is a key problem that must be solved urgently at the beginning of 21th century in China. Widening of highway on soft ground may meet with the issues such as the interaction of the old and new embankments, the juncture of old and new abutment, differential settlement and pavement cracking along the joint between the old and new embankments. Unfortunately the systematic analysis of performance and treatment techniques of widening are scarce. The interaction and differential settlement between the old and new embankments are researched in this paper. (1) Based on the review of widening of highway, a comprehensive introduction is given to the problems of widening on the soft foundation such as the calculating methods, the soft foundation treatment design, linking measures of new and embankments, the controlling criteria about the settlement of new embankment and differential settlement of the new and old embankments.(2) The finite element technique using a Mohr-Coulomb elastic-plastic soil behavior model are applied to the analysis of interaction mechanism between the old and new embankments in the widening of highway embankments on soft foundation soils. Conclusions are gained that the construction of new embankment induce differential settlement between the center and the shoulder of old embankment, then pavement cracking is come forth and the grade of highway is debased. Right treatment techniques should be taken to reduce the influence of the widening on the old embankment.(3) Dry Jet Mixing (DJM) and diaphragm wall should be applied separately to shallow soft soils and deep soft soils in widening of highway. The FEM are applied to the analysis of the deformation features of embankments, and the location, strength and thickness of diaphragm wall are studied. (4) Based on the functionality request and structural request of pavement, tolerant differential settlements are researched in widening of highway. Then post-construction settlement calculating formula of a section of a highway and a connection section with a bridge are put forward separately.