To explore shearing mechanical characteristics of the interface between thawing soil and structure interface

a series of direct shear tests was performed by using an improved DRS-1 high-pressure direct shearing system. The results showed that the normal stress and the thawing temperature presented remarkable effects on the shear strength of thawing soil-structure interface under high pressure. Both the peak and the residual shear strengths of the interface increased with the increase of the normal stress. The increasing rate of the peak shear st

rength was less correlated to the thawing temperature（between 0.36 and 0.46

mean value 0.43）

while the rate of the residual shear strength increased obviously(Under testing conditions

mean value is 0.26 at T

thaw

=-10 and -5 ℃

mean value is 0.49 at T

thaw

=-2 and +0

3

℃). At the higher stress level

the increasing rate of the peak shear strength with normal stress was about 2/5 of that at the lower stress level. The demarcation stress range was about 1

3

MPa for high and low stresses. With increasing the thawing temperature

shearing stress-displacement curve gradually transformed from strain-hardening to strain-softening

which showed significant peak shear stress. Furthermore

the normalised peak shear strength decreased slowly when it was subjected to a relatively low temperature. However

with further increasing the thawing temperature

the differences of normalised peak shear strength under various normal stresses was decreased

until converged to a narrow range value.