Research On Settlement Deformation Characteristics Of Embankment Filled With Foam Concrete On Deep Soft Ground

Foam concrete has the advantages of light texture,minimal apparent density,high flowability and so on,as a new type of filling material.It has been gradually used in the filling of soft foundation embankment and the abutment in recent years.However,it has not been effectively popularized,due to the lack of adequate design basis and rich construction experience.Based on the study of the settlement distribution of soft soil subgrade and the theoretical calculation of settlement,combined with an actual road foam concrete soft soil subgrade treatment project in Fujian,the settlement deformation characteristics of a foam concrete replacement embankment similar to Fujian Xiapu deep soft soil area are studied.The research results can provide a reliable design basis for subgrade treatment project in deep soft soil area,and promote the application of lightweight foam concrete in this field.(1)Using the on-site settlement monitoring results combined with the analysis of the settlement mechanism,the settlement characteristics of the three components consist of the final settlement on the roadbed were studied.The four types of settlement distribution of soft ground under the action of embankment are summarized,and the calculation method of total settlement after overload-unload-reload of lightweight material displacement roadbed is introduced.(2)During the pre-compression stage of embankment,the distribution of uneven settlement on the surface of the foundation,the dissipation of excess pore pressure of the soil and the horizontal displacement at the foot of the embankment calculated through numerical simulation are consistent with the on field monitoring results.The deviation is within the allowable range.(3)Through numerical simulation,the engineering superiority and internal mechanism of foam concrete replacement embankment in controlling the settlement of soft soil roadbed are demonstrated.The comparison results show that the weight loss effect of lightweight materials is the most important reason that foam concrete displacement embankment can effectively control the settlement deformation.In addition,the stiffness correction effect of foam concrete displacement embankment plays an important role in embankment settlement control.The existing settlement calculation theory can reasonably consider the weight reduction effect,but cannot consider the stiffness correction effect.Therefore,it is necessary to establish an embankment settlement estimation method based on embankment settlement calculation method that considers foam concrete replacement embankment stiffness correction.(4)Based on a series of typical working conditions,such as the thickness of soft soil,the height of different embankments and the level of foamed concrete,the quantitative effect of foam concrete stiffness contribution on the embankment settlement distribution was analyzed and calculated.The settlement correction coefficient? was proposed to characterize the effect of embankment stiffness contribution on the reduction of ground settlement.Under the effect of different stiffness foam and embankment,the statistical relationship between embankment fill height and soft soil thickness approximately satisfies the linear relationship,the slope of fitted line(settlement of foam foam embankment with unit stiffness under unit height)and foam embankment stiffness There is a decreasing power function relationship between them.Based on the above results,based on the settlement calculation method for soft flexible ordinary embankment,the formula for estimating the settlement of soft foundation under the function of foam embankment considering the correction of stiffness is concise.