Soft Soil Subgrade Treatment Technology On Municipal Roads In Zhoushan Region

Municipal roads in soft soil region usually have problems such as slope instability,insufficient carrying capacity,pavement cracks caused by uneven subgrade settlement,bridgehead jump-driving and so on.Especially,with the urban development achieves a certain scale,the construction of urban municipal infrastructure has gradually shifted its focus from making roads to renovating and expanding existing roads.Old roads with nearly more than 10 years of use have been unable to satisfy today’s requirements for roads,no matter in terms of vehicle load design or traffic volume design.Width reconstruction of fast roads,main roads and secondary trunk roads has become a very essential part of municipal construction nowadays.Full section foundation treatment and the width treatment of new and old subgrade have become important research projects on soft soil foundation treatment.This paper chose the urban road in Zhoushan region as the research object.By summing up the geological conditions and the features of road construction of each region in Zhoushan,this paper divided Zhoushan into Donggang reclamation area,Xingang industrial park phase II,Southern region of the main land,Baiquan Town and Yushan Island,and concluded some problems encountered in the process of soft soil foundation treatment of municipal roads construction in each area.Longitudinal cracks in the rban road intersections,pavement cracks and base reflection cracks are the main types of pavement disease for Zhoushan municipal roads.This paper analyzed the reasons of above disease.Donggang is a newly formed urban area through reclaiming land form the sea,and foundation secondary consolidation settlement there has not been over yet.Therefore,phase I pavement could be applied for initial use,then phase II pavement should be re-constructed according to settlement difference after the settlement has been basically over.The geological condition of Xingang industrial park(Phase II)is poor,sand and gravel reclamation area exactly.Thus dynamic compaction replacement method would be feasible in this region.The southern region of the main island mainly uses high-pressure jet grouting pile and nail cement bidirectional mixing pile to reinforce the soft soil foundation.The advantages of such method are having less interference with the formed parcel,having higher bearing capacity of composite foundation,having smaller post-construction settlement and economical cost.Yushan Island would be suitable to apply gravel pile combined with plastic drainage board to consolidate,cuase such method has small post-construction settlement and less groundwater interference.