Experimental Study On The Effect Of Infiltration Process On Loess Properties

Loess is highly sensitive to changes in the water environment.The possibility of landslides after irrigation and heavy rains is very high,causing threats and losses to people's lives and property.The effect of infiltration process on properties of loess was studied by testing samples from Yehugou and monitoring wetting front,recording settlement deformation of soil column and seepage water from soil column during penetration test and testing ion concentration,particle size gradation,microstructure and strength after penetration test.The research results can provide theoretical basis for water infiltration process in subsequent loess and provide a theoretical basis for disaster prevention and mitigation in loess area.The main conclusions are as follows:(1)During the initial infiltration phase,the infiltration rate of wetting front changes from fast to slow from top to bottom of soil column.At the beginning of permeation test,a large amount of soluble salts that act as a cement are dissolved and leached.After that,Ca CO₃ in soil column reacts with H₂O and CO₂ to form calcium bicarbonate,and the Ca²⁺produced by reaction replaces Mg²⁺in the counter ion layer,meanwhile,the soluble salt is dissolved continuously and the primary mineral is hydrolyzed continuously.(2)In the experimental process,the soluble salt in soil column is dissolved and leached for the disintegration of clay particles in cement,then the disintegrated clay particles migrate downward through pores between coarse and fine particles under the driving of hydraulic force.Clay particles lost in the upper part of soil column fill pores in the lower part of soil column.With the position of sample in soil column downward,the clay content increases and the porosity decreases.(3)In the process of penetration test,the soluble salt which plays a cementing role in soil column is dissolved and leached,and the clay particles in cement migrate downward under the driving of hydraulic force,so the degree of cement in soil column decreases,and the composition and properties of cemented substance determine the strength of rock and soil,so the strength of sample decreases after penetration test.