Abstract: In order to investigate the strength and deformation characteristics of the undisturbed sample of permafrost under vertical and outward loading, uniaxial tests and consolidation tests were performed on undisturbed samples of permafrost with different depths to analyze the compressive strength, Elastic Modulus, failure pattern, and thawing characteristics of frozen soil. The test shows that the stress-strain curve of the shallow soil is an irregular nonlinear curve and the stress-strain curve of the deep soil is a parabolic curve in the uniaxial test. As the ice content increases and the sand content decreases, the bearing body of load is developed from the soil particle skeleton to ice crystals, and the compression strength and elastic modulus decrease first and then increase with the increase of soil depth. Failure of frozen soil is divided into three types: there are no obvious cracks on the outside when ductile failure occurs, and only compression deformation occurs; shear failure on the weak surface leads to the lateral cracks and lateral compression deformation; cracks of brittle failure expand from the middle part to the axis. In the consolidation test, the main consolidation generally occurred in the first 100 minutes; the consolidation strain and thawing coefficient of the deep soil are larger than those of the shallow soil layer and the deep soil layer thawing settlement coefficient is greatly affected by the load.

Key words: compressive strength, failure shape, elastic modulus, melting settlement coefficient, compression coefficient