Mechanical properties of soft soil will change under freeze-thaw cycle with a certain confining pressure in artificial freezing engineering in coastal soft soil area. Therefore

it is of a great significance to study the influence of freeze-thaw cycle under different confining pressures on the mechanical properties of soft soil. This paper takes the typical muddy soil in Tianjin coastal area as the research object. Through a self-improved temperature controlled triaxial apparatus

the differences of mechanical properties of soft soil under conventional freeze-thaw without confining pressure and freeze-thaw with confining pressure are compared and analyzed. Furthermore

the effects of freezing temperature

number of freeze-thaw cycles and freezing-thawing confining pressure on excess pore pressure

stress-strain characteristics

strength and deformation index of soft soil are revealed. The influence mechanism of freeze-thaw confining pressure on the mechanical properties is explored by SEM. Then

the relationship of shear strength

reduction coefficient of elastic modulus of muddy soil and above influence factors is established by using an exponential function. The results show that the freezing and thawing confining pressure reduces the size and number of pores in the soil after freezing and thawing

which can weaken the damage of freezing and thawing to the soil structure to a certain extent. However

the freeze-thaw confining pressure has little effect on the stress-strain curve. With the decrease of freezing temperature and the increase of the number of freeze-thaw cycles

the strength and moduli of soil are greatly reduced. With the increase of freezing-thawing confining pressure

the freezing temperature and the decrease of the number of freeze-thaw cycles

the excess pore pressure decreases.