Study Of Mechanism And Countermeasure On Asymmetric Settlement Of Soft Soil Subgrade

Road construction on soft soil is a difficult technical problem of geotechnicalengineering. At present, there is no good solution method to this problem domesticand overseas. Experience shows that, even if a vatiety of measures were taken to thesoft soil road foundation. Many problems will appear in use for a period of time.Building roads in soft soil foundation, deformation is the main factor of controlquality and normal use. The continental assessment of Dongjiang harbour district isbasically formed by vacuum preloading, which belongs to the soft soil foundation oflow strength and large compressibility. The serious "wave" uneven settlement afterthree years’ use, which seriously effects vehicle driving and people’s life safety.Settlement deformation with time of super soft soil foundation in the roadsurface load and the traffic load can be divided into instantaneous settlement(extrusion deformation), primary consolidation settlement, and secondaryconsolidation settlement.Instantaneous consolidation and consolidation and secondary consolidation takeplace at the same time after stress, just in a stage one of the settlement deformation isprimarily, and three parts’ relative size and time are changed in different different soil.When the foundation is uneven or the uneven settlement happens in soft soil, whichwill aggravate the pavement structure ‘s damage.It shows that pavement cracks andthe vehicles through the uneven settlement will jump. This paper based on thepractical construction of the Dongjiang port, through the field investigation and themeasured data, this paper analyzes the soft soil subgrade settlement deformationmechanism, Measurement and the field test of road’s structure layer and ground stateby the agent pit test,which analyze the cause of destruction road embankment, at thesame time, using the finite element method to simulate the embankment settlementdeformation process,which is: instantaneous settlement, consolidation settlement andCumulative residual settlement caused by vehicle dynamic loading. This paperanalyses deformation mechanism of the soft soil subgrade through the establishmentof the mechanical model, and puts forward the the initial deformation of the roadgenerating after the completion, and the vehicle load intensifies the uneven settlement.At the same time this paper analyes design concept of building road in soft soil andproposes the design method of reducing uneven settlement of the roadbed. Proper treatment for the super soft soil subgrade can reduce foundationsettlement and uneven settlement. The normal service life can be extended.Reinforcement of geogrid can reduce the uneven settlement of roadbed. Through theanalysis of the finite element method, this paper Indicates the effect and mechanismof the reinforcement effect of laying position. Proposed that the geogrid can reducethe uneven settlement of roadbed obviously. In the middle of subgrade structure andsoft soil, geogrid can reduce the uneven settlement largest. Two or three layers ofGeogrid in different subgrade structure locations can decrease settlement.