The Research On Settlement And Deformation Control Of Shallow Solidified Soft Soil Foundation Under Traffic Load

Soft soil is widely distributed in coastal areas of our country.With the continuous economic development of coastal areas,it is inevitable to use soft soil as foundation when building roads.Soft soil,as a kind of poor soil mass with high compressibility,Soft soil needs to be replaced or reinforced.Based on the Niutianyang Expressway Project in Shantou City,this paper studies the dynamic response and settlement and deformation law of the underlying soft soil foundation using surface solidification measures.First,the physical and mechanical parameters of the undisturbed soil are determined based on the engineering report and other data,combined with the settlement monitoring data,the compressive modulus of the solidified layer is calculated back to provide a basis for the selection of numerical simulation parameters.;then carry out dynamic triaxial tests of soft soil with different confining pressures,dynamic load amplitudes,and single load loading time,and analyze the dynamic parameters and plastic permanent deformation laws.;then carry out numerical calculation to analyze the influence of different elastic modulus and thickness of the solidified layer on the dynamic stress response and settlement deformation of the top surface of the underlying soft soil foundation;Finally,Establishing a mathematical empirical model based on the law of plastic permanent deformation,a settlement prediction model is established by combining the permanent deformation empirical model and the layered sum method,and corresponding settlement deformation control measures are proposed according to the settlement deformation law.The main conclusions of this study are as follows:(1)The plastic permanent deformation of soft soil gradually increases with the increase of loading times,and finally tends to be stable;the plastic permanent deformation of soft soil decreases with the increase of confining pressure,increases with the increase of dynamic load amplitude,and increases with the increase of confining pressure.It increases with the extension of the single load loading time;the development law of the soft soil plastic permanent deformation under the lower horizontal dynamic stress conforms to the hyperbolic model.(2)The dynamic elastic modulus gradually decreases with the increase of loading times,and finally tends to be stable;and the dynamic elastic modulus of the soil increases with the increase of confining pressure,dynamic load amplitude,and single load loading time.;The damping ratio increases with the increase of the loading times,and finally tends to be stable;the damping ratio decreases with the increase of the confining pressure,and increases with the increase of the dynamic load amplitude and the loading time of a single load.(3)As the thickness of the solidified layer increases,the dynamic load on the top of the substratum soft soil gradually decreases.When the thickness of the solidified layer exceeds 2 m,the influence on the dynamic load on the top of the substratum soft soil gradually weakens.Under different moduli,when the thickness of the cured layer increases from 1m to 3m,the dynamic stress decreases by about 70%～75%;with the increase of the modulus of the cured layer,the dynamic load on the top of the soft soil gradually decreases,but the decreasing rate is slow.(4)With the increase of the thickness of the solidified layer,the settlement of the top of the soft soil of the substratum gradually decreased;when the thickness of the solidified layer increased from 1m to 3m,the settlement of the top of the soft soil of the substratum decreased by about 45%～55%.With the increase of the modulus of the solidified layer,the settlement of the top of the substratum soft soil gradually decreased,but the elastic modulus had little effect on the settlement of the top of the substratum soft soil.(5)The dynamic stress diffusivity of the cured layer decreased gradually with the increase of thickness,the dynamic stress diffusivity decreased with the increase of the modulus ratio.