ATTENUATION RULE AND MECHANISM OF COMPRESSIVE STRENGTH OF FROZEN SOILS SUBJECTED TO EXTERNAL DISTURBANCE
The strength of soil is a key technical indicator during construction work in cold areas.The influence of external disturbance on the compressive strength of frozen soil is investigated,in which unconfined compressive strength of undisturbed and remolded frozen soil is measured in laboratory experiments.The results show that the strength of undisturbed frozen soil rapidly decreases within 10 disturbances and then stabilizes down with the residu-al strength ratio about 0.3.The strength of remolded frozen soil decreases in an arc type with the number of distur-bances,and the residual strength ratio is less than 0.1.The reasons for the strength attenuation of frozen soil are ice crystal lattice fracture,soil particle colloid fracture,and temperature rise.For undisturbed soil,the strength attenua-tion caused by structural failure cannot be ignored.Through electron microscopy experiments,the number of soil par-ticles per unit area increases after disturbance and the effective particle size decreases.Except those,the particle shape becomes regular and there is no significant change in the morphology of the reshaped soil particles.Finally,the strength loss mainly results from the loss of ice bonding force.