Experimental Study On Mechanical Properties Of Artificially Frozen Silty Clay

Artificial freezing method,mainly use the artificial refrigeration technology,the formation of water into ice,which not only effectively enhance the soil strength and stability,but also isolated from the groundwater and underground engineering links for the construction of the road to provide frozen Wall protection.Artificial freezing method as a temporary reinforcement of the foundation of the construction method,in the subway tunnel shield origin and receiving end reinforcement,contact channel reinforcement construction,tunnel rescue and other emergency engineering and other urban underground construction has been widely used.This paper mainly studies the thermophysical characteristics,strength characteristics and frost heaving characteristics of artificial frozen soils,and provides the necessary technical support for artificial freezing construction and design.The main research contents are as follows:(1)Triaxial tests were carried out to study the factors that affect the mechanical properties of the soil during the three artificial freezing processes,including temperature,confining pressure and water content.It was found that the soil was prone to occur in low confining pressure Shear stress,the stress-strain curve will appear obvious peak strain softening type;and in the high confining pressure,soil stress-strain curve was strain hardening type.(2)the strength of the soil sample will increase with the increase of the confining pressure,but when the confining pressure increases to a certain value and further increases,the frozen soil strength will occur nonlinear attenuation,that is,silty clay Saturated water content under the conditions of the existence of critical confining pressure,and this critical value is about 1000 kPa.(3)Based on the Duncan-Zhang model,the constitutive model of frozen silty clay with different confining pressure and temperature conditions was established by analyzing the data of the triaxial test.The influence of temperature on the model parameters and the relationship between the parameters and the temperature and confining pressure.(4)The frost heave test was carried out by changing the temperature and soil water content as the starting point.It is found that the amount of frost heave increases rapidly with the increase of freezing depth,and most of the frost heave deformation occurs in the early stage of the one-way freezing process.(5)After the frost heave test,the soil moisture content of the soil samples was lower than the initial water content,and the water content in the frozen soil was higher than the initial water content.It is shown that the phenomenon of water migration occurs during the frost heave test.