Experimental Study On The Static And Dynamic Characteristics Of The Improved Subgrade Soil Of Harbin-jiamusi High-speed Railway

China’s railway construction is in the rapid development,the demand for building materials is increasing,the selection of existing materials to improve the treatment according to local conditions,in order to meet the strength and deformation stability of railway subgrade requirements,in the high-speed railway subgrade engineering construction attention.However,for the subgrade engineering in the seasonal frozen soil area,because the repeated freezing-thawing effect will affect the strength and deformation characteristics of the improved subgrade soil and shorten the service life of the subgrade,therefore,the improved effect of the improved material on the subgrade soil in the seasonal frozen soil area seriously affects the development of the improved subgrade in the seasonal frozen soil area.Therefore,it is urgent to study the static and dynamic characteristics of roadbed soil under the action of freezing-thawing and train dynamic load.In this paper,a series of static and dynamic triaxial tests are carried out to investigate the static and dynamic characteristics and long-term stability of the improved roadbed soil of hajia high-speed railway in the seasonal frozen soil area.(1)carry out static triaxial test on the improved subgrade soil with different improved materials,confining pressure,dosage of curing agent and times of freezing-thawing cycle,and analyze which improved material has better reinforcement effect among the three improved materials: lime,cement and curing agent;At the same time,the relationship between stress and strain,peak strength and residual strength were studied,and the strength and deformation characteristics were discussed.(2)study the dynamic parameters of the triaxial test of the improved roadbed soil with different improved materials,confining pressure,curing agent content and freezing-thawing cycle times,analyze the backbone curve and dynamic modulus attenuation law of the improved roadbed soil under different factors,and explore the influence of the four influencing factors on the dynamic characteristics of the improved roadbed soil.(3)with different dosage of modified materials,confining pressure,curing agent,the improved road foundation soil freeze-thaw cycles into the dynamic triaxial test to study the cumulative plastic deformation features,analysis of improvement of subgrade soil under different dynamic stress amplitude level,the cumulative plastic strain with vibration times growth curve,analysis of modified materials,confining pressure,curing agent dosage,freezing and thawing cycles to improve the influence law of subgrade soil cumulative plastic strain,determine the type of the cumulative plastic strain curve,improved the cumulative plastic strain of subgrade soil prediction model is established,to improve the further research of permanent deformation characteristics of subgrade soil accumulation of information.(4)by studying the effects of different improved materials,confining pressure,dosage of curing agent and number of freezing-thawing cycles on the critical dynamic stress of the improved subgrade soil,an empirical formula for estimating the critical dynamic stress of the improved subgrade soil is proposed,which can be used as the basis for evaluating the dynamic response characteristics and dynamic stability of the subgrade soil.