Study On Mechanical Properties Of Ash-improved Saline Soil Under Freeze-thaw Cycles

Saline-alkali soil was widely distributed in the deep seasonally frozen ground regions of Northeast China.Under the influence of salinization and freeze-thaw cycles,the engineering property of soil seriously affects the local regional construction and economic development.Therefore,the research on the engineering property improvement of saline soil has become the frontier hot issue of engineering construction in frozen and salinization soil area.Based on Open Fund Project of the State Key Laboratory Frozen Soil Engineering of CAS(SKLFSE201919),this paper carried out the mechanical properties test of saline-alkali soil in Durbert area of Daqing,explored the change regularity of mechanical properties of solidified saline soil under the influence of various factors,and analyzed the mechanism process under the change law of macroscopic mechanics.The ANOVA method was used to quantitatively analyze the influence of five influencing factors,including lime content,fly ash content,freezing and thawing cycles,confining pressure and salt content,on the shear strength of solidified saline soil,and to determine the weights of different influencing factors.The artificial neural network method was used to model the shear strength of solidified saline soil,and the influence of different hidden layer nodes on the accuracy of the model was analyzed.The model error analysis was carried out to determine the optimal number of hidden layer nodes.Coupled thermo-mechanical FEM model of solidified soil subgrade is established to analyze the variation law of temperature field and deformation field of solidified soil subgrade with time,and to explore the applicability of lime-fly ash solidified soil in subgrade engineering.