Experimental Study On Disintegration And Latent Corrosion Of Granite Residual Soil

The hot and rainy regions of southern Jiangxi are seriously affected by acid rain,which can easily cause soil erosion.Collapsing erosion is the main part of soil erosion in the south of Jiangxi Province,causing great damage to the land surface structure.At the same time,a large amount of sediment is flushed to farmland and rivers under the influence of currents,causing huge damage to crops and vegetation,and seriously affecting the social and ecological environment.Therefore,as the main soil type in the region,the nature of granite residual soil is closely related to the collapse of granite.As a kind of soil that is easy to disintegrate and soften under water,it is very important to study its water sensitivity.In this paper,based on the disintegration characteristics and latent corrosion mechanism of granite residual soil,indoor experiments were conducted with reference to the local climate and other conditions.Based on the existing disintegration test equipment,a controlled temperature disintegration tester was used to test the disintegration of granite residual soil.The effects of mesh size,temperature,water content,dry density,and acid rain on the disintegration of reconstituted soils in granite residual soils were studied.A soil column test was conducted on the residual soil of the granite residual soil by a self-made soil column tester to study the influence of the soil column angle and flow rate on the accumulation of fine particles,changes in water content,pore pressure and wet front.The Geo-studio was used to simulate the soil column submerged corrosion test,and compared with the actual soil column submerged corrosion test,the influence of the subsurface eclipse on seepage was analyzed.The main research contents and results are as follows:1.The disintegration test of granite remnant soil samples under different mesh aperture sizes,different temperatures,different water contents,different dry densities,and different acid rain conditions was conducted.The analysis of the experimental data showed that: The aperture size of the mesh has a great influence on the disintegration test,and the disintegration rate is faster when the pore size is larger.The disintegration rate of the sample in the aqueous solution with lower temperature is slower,and it is very fast when the temperature is high,and it is difficult to distinguish between the water saturation stage and the severe disintegration stage.With the increase of water content,the water saturation time of soil samples shortened and the disintegration rate increased.With the increase of dry density,the disintegration of remolded soils in granite residual soil decreased.2.Soil column latent erosion tests were conducted on granite residual soils under different angles and flow conditions.The test results showed that: The increase of the water seepage velocity increases the cumulative amount of fine particles lost in the soil column,and the increase of the angle of the soil column increases the cumulative amount of subsurface fine particles.The formation of preferential flow channels in the soil column and the re-deposition of fine particles will affect the water content in the soil column and the advancing speed of the wet front;When the soil column angle is 90° and the direction of seepage flow is from top to bottom,the re-deposition phenomenon of fine particles is more obvious;the increase of the angle of the soil column and the increase of the water flow speed up the advancement of the wet front in the soil column.3.By comparing the simulation results with the experimental results,it is found that the variation between the two is similar,but the simulation results do not take into account the formation of preferential flow channels and the re-deposition of fine particles,therefore,there was no fluctuating sudden change in the moisture content at the later stage.The simulated wetting front speed was less than that obtained from the test.