Research On Differential Settlement Controlled Techniques In Highway Widening Engineering

In recent years, the capacity of four lanes of highway can not meet requirement, there is an urgent need to widen the highway to six or eight lanes. But as the differences between new and old ground of the road, especially the soft ground, there is differential settlement between the new and old subgrade, which will break pavement and affect the use of highway. Therefore, there must be a strict request on controlling of the differential settlement between new and old subgrade. On the basis of the analyzing and summarizing the results of research on differential settlement in highway widening engineering at home and abroad and combining with the relevant existing standard, the features of differential settlement, control criterion and control methods are researched systematically. The main contents are as follows:(1)Based on comprehensive analysis of the situation on the widening of highway at home and abroad , the major problems existing on the widening of highway for soft ground are preliminary analysed.(2)The interaction features between new and old subgrade are analysed. It indicates that the differential settlement of subgrade will lead to uncoordinated deformation on the top of the subgrade, Showing "~". The Location of the largest additional stress is the centroid of widening section. And there are further analysises on the impact of the filling height, modulus of the ground, widening width and other factors on differential settlement. (3) Through the analysis of the control criteria about widening the subgrade at home and abroad, the calculating methods on post-construction allowable settlement and the beginning time for construction the pavement are worked out(4)On the basis of getting an enough cognition on the differential settlement, raising bearing capacity of sound, applying those light materials and other measures are used to control differential settlement. And some measures are compared on technology and economy.(5) Deformation characteristics about DJM pile dealing with soft ground are analysed. And with the example of DJM dealing with Shanghai-Hangzhou highway widening ground, calculating method of DJM pile dealing with soft ground is introduced in detail. All the results of these research referential significance for the other highway widening poject.