Abstract: The degree of saline soil in Qian’an area, western Jilin Province increases gradually with the change of climate. Especially in the rainy season in July and August, the local engineering buildings are easily damaged due to the long-term impact of rain erosion and river erosion. In order to prevent from this damage, a new type of hydrophobic material (CN) was used to treat saline soil, and the effect of CN on the mechanical strength of saline soil under different treatment conditions was studied, and the unconfined compressive strength of soaked soil and CN soil was compared. The results show that: 1) Under different water content, the unconfined compressive strength of CN soil has been greatly improved, and the maximum rate of increase is 98.90% at 14.86% moisture content. With the increase of water content, the stress-strain curves of plain soil and CN soil change from hardening type to softening type, and the threshold value is near the optimal water content. 2) With the increase of compactness, the unconfined compressive strength of saline soil improved by CN increased gradually, and the maximum improvement rate of 130.77% was achieved under the condition of 90% compactness. After CN treatment, the original plastic hardening type of plain soil is transformed into brittle softening type. 3) The increase of salt content can inhibit the unconfined compressive strength of CN soil, the maximum unconfined compressive strength of CN soil is 1.33 MPa at 0.3% salt content. Excessive salt crystallization will destroy the nanostructured hydrophobic membrane formed by CN, which makes the compressive strength of CN soil lower than that of plain soil under the condition of high salt content. 4) Scanning electron microscope (SEM) test was used to explore the micro mechanism of CN soil. After CN treatment, the soil particles agglomerate into large particles, the surface of particles is smooth, and the pore development is reduced. The analysis of structural units and pore units proves that the soil is connected more closely after treatment, thereby improving the compressive strength.

Key words: saline soil, super-hydrophobic material, unconfined compressive strength, microanaly-sis, Qian’an area,western Jilin Province