Experimental Study On Moisture Migration Of Unsaturated Loess Under The Action Of Electric Potential

Water content has a great influence on the strength and stability of unsaturated loess.Reducing the water content of unsaturated loess is the main means to improve the stability of loess foundation and soil reinforcement.Reducing the water content of the unsaturated loess by electroosmosis can form a low water content slope,which greatly improves the stability of the soil.At present,the electroosmotic technology is mostly used for the drainage consolidation of saturated soft soil.The electroosmosis study of unsaturated loess is still in the preliminary exploration stage.In order to explore the moisture migration results of unsaturated loess after electroosmosis under different initial conditions,this paper selects unsaturated Malan loess in Xi'an.The DC electric field was applied to the soil during the test to study the effect of the potential on the moisture migration of unsaturated loess.In order to investigate the influencing factors and moisture migration of unsaturated loess,the electroosmotic test of one-dimensional unsaturated remolded loess was carried out by self-made indoor test device to study the different energization time,potential,saturation,and salt content on loess moisture.The test results show that there is no liquid water discharge from the cathode during electroosmosis of unsaturated loess.The amount of moisture migration increases with the extension of the energization time.The moisture migration rate decreases with the extention of the energization time,and the greater the dry density,the more significant the effect of the energization time on the moisture migration.Under the potential gradient of 0.5 to 1.5V/cm,the moisture migration result of unsaturated loess increases with the increase of potential gradient,and the larger the potential gradient,the more severe the electrochemical reaction,the smaller the change of moisture content near the cathode,and the higher the current reduction rate.When the dry density is small,the smaller the saturation,the more obvious the soil moisture migration result;when the dry density is larger,the saturation is larger,and the moisture migration result is more obvious.The content of soluble salt in the composition of loess is high,and the salt content has a great influence on the engineering properties of unsaturated loess.The greater the salt content,the greater the corrosion of the electrode.The moisture migration increases first and then decreases with the increase of salt content,and the moisture migration result is the most significant when the salt content is between 0.25% and 0.5%.According to the one-dimensional remolded loess test,the relationship between the water content gradient of the anode region and the initial water content and potential gradient after electroosmosis is proposed.Through the one-dimensional electroosmotic test of unsaturated undisturbed loess,it is found that the original loess also undergoes moisture migration under the action of potential,and the water content in the anode region decreases,and the water content in the cathode region increases,which is consistent with the electroosmotic test results of the remolded soil.In the actual engineering application,the electro-osmosis method using the rod electrode belongs to the two-dimensional electroosmosis problem.Two-dimensional unsaturated loess electroosmosis test in different electrode arrangement forms was carried out by self-made test boxes to compare the moisture migration in two-two double row electrode arrangement,three-three double row electrode arrangement,three-row electrode arrangement and hexagonal electrode arrangement.The test results show that the anodic potential drop of the four electrode arrangements increases with time.The moisture migration result of the row electrode arrangement is more significant than that of the hexagonal electrode arrangement.Under the arrangement of the row electrode,the smaller the distance between the isotropic electrode and the opposite electrode,the larger the effective area ratio,the larger the effective potential gradient,and the more obvious the effect of moisture migration.In the hexagonal electrode arrangement,the effective electric field rate is relatively large due to its special arrangement,and the current reduction rate is small,but the moisture migration result is relative small.