Research On Differential Settlement And Treatment Technology In Express Highway Widening Projects

Since the new century, with the large increase of traffic volumes, the traffic capacity of some highway cannot meet the needs of economic rapid development, and hinder the regional economy developping seriously. So must be carried out on part of the highway widening and reconstructing. Relevant specifications only make a few simple instructions for highway reconstruction and some provisions for widening subgrade in principle, staff can work only with the past project experience. So must be studied the relevant situation of highway widening project thoroughly, and the differential settlement of new and old subgrade is the main research direction.SuiNing west traffic hub widening engineering of Xuzhou to Mingguang highway in jiangsu adopt single horn hub type. It has to do with NingSuXu highway into T cross, and exist local joining together, including: directional ramp, unidirectional lane ramp and two-way two-lane ramp. On the basis of investigating a large number of highway widening projects and analysising the existing problems and related treatment technology preliminary, combine with SuiNing west traffic hub widening engineering, and set up the finite element analysis model,and analysis different factors’ influence on the differential settlement of widening subgrade. The factors include: the widening way and width, the filling height of widening subgrade, the different modulus of new and old subgrade, the different consolidation degree of new and old foundation. In order to reduce the differential settlement of new and old subgrade, cut the old subgrade slope and excavate steps, and lay large room technical measures research.Through the analysis and summary research and get that: double side widening have more advantages than unilateral broadening; The increase of subgrade filling height or width has great influence for differential settlement of new and old subgrade and horizontal displacement of subgrade slope toe; The change of new subgrade’s elasticity modulus has influence for the maximum differential settlement of new and old subgrade; Different consolidation degree of new and old foundation have great influence for differential settlement of new and old subgrade and horizontal displacement of subgrade slope toe; Cutting old subgrade in 1:1.25 slope and digging steps with 80 cm high and 100 cm wide is more reasonable, and then laying two layers of large room at the bottom of the new subgrade can reduce the differential settlement of new and old subgrade better, and improve the stability of the new and old subgrade; In addition,under the condition of differential settlement of new and old subgrade, I analyse the width of steps for the structure stress influence of new and old pavement, and results have showed that the width of 60 cm is more reasonable.