Study On Consolidation Creep Characteristics And Settlement Of Pingtan Coastal Soft Soil

The soft soil in Pingtan coastal area is widely distributed.The rheological properties of soft soil easily lead to ground settlement cracking and loss of fill height,which in turn affects the structural stability of the upper building and its safety during long-term use,and thus triggers a series of geological disasters.Therefore,it is of great practical significance to carry out research on the consolidation and creep characteristics of soft soil foundation in Pingtan coastal area and post-construction settlement.Firstly,based on the one-dimensional consolidation test,the creep behavior test of soft soil in Pingtan coastal area is carried out.Secondly,according to the consolidation creep model of soft soil in Pingtan coastal area,the characteristics of creep settlement in deep soft soil area are analyzed.Compared with the settlement without considering the soft soil creep,finally,based on the actual project settlement monitoring data,it is concluded that the soft soil consolidation creep model can be applied to the Pingtan coastal area.The work done in the paper is mainly as follows:(1)To carry out routine geotechnical tests of soft soil in Pingtan coastal area.The natural void ratio of soft soil in this area is more than 1,and the natural moisture content is obviously higher than the liquid limit.At the same time,the field cross shear test shows that the sensitivity of soft soil in this area is more than 4,which can be judged as structural soft soil.(2)Based on the indoor one-dimensional consolidation test,the characteristics of soft soil main consolidation and creep(sub-consolidation)are analyzed.The test shows that the soft soil consolidation pressure is 78 kPa,which is normal consolidation soil;soft soil void ratio e It is roughly inverse S-shaped curve with time log lgt.With the increase of loading ratio,the anti-"S" curve changes more significantly;the secondary consolidation coefficient increases first and then decreases with the increase of consolidation pressure.The trend tends to be stable at the end;the maximum value of the secondary consolidation coefficient and the stability value of the loading ratio are also increased;by calculating the consolidation pressure of the soft soil "p ? 100 kPa",the ratio of the secondary consolidation coefficient to the compression index The range is between 0.025 and 0.050.(3)Based on the traditional D-P model,an extended D-P consolidation creep model suitable for deep soft soil in Pingtan coastal area is obtained.The parameters m,n and A can be fitted by one-dimensional consolidation test data.Then,through contrast analysis,the conventional D-P model is used to consider the creep settlement without considering the creep settlement and the extended D-P model.Finally,it is concluded that the creep factor does not occur after the work,and the creep factor will occur after the work.The continuous and slow settlement,in the period of two months and two months,the final settlement value caused by creep accounts for 15.6% of the total settlement value,so the settlement value can be better predicted by considering the influence of creep.(4)Using finite element software calculations,carry out a finite element numerical calculation of the influence of consolidation creep model parameters m,n,A on the settlement calculation of buildings above soft soil.The calculation results show that the creep parameters n,A are positively correlated with the calculated settlement values.A reflects the magnitude of the creep rate of the soil,and also reflects the structural composition of the soil to a certain extent;the parameter n reflects the result of the effect of the partial stress on the creep rate;the parameter m is positively related to the calculated settlement value,and its value controls The rate at which creep decreases over time.The value of parameter n has a greater effect on the settlement of soft soil,while parameter A has the least effect on the creep settlement.(5)Based on the actual project,the finite element method is used to calculate the settlement trend and settlement value of the upper part of the soft soil foundation.Combined with the measured data,it is verified that the creep model used has high reliability.