Effect Of Electrochemical Reinforcement On Soil Shear Characteristics In Collapsing Wall

Collapsing gully?locally called benggang?is one of the most serious and harmful erosion types in red soil region of southern China.The collapse wall is the key process of erosion development.Although some achievements have been made in the treatment of collapse wall at present,however,there are still some problems in traditional harnessing measures,such as high cost,long period,disturbance to the environment and inapplicability of special terrain.The electrochemical reinforcement method has the advantages of fast reinforcement speed,no need for large-scale excavation and little disturbance to the environment.Therefore,for the purpose of in-situ reinforcement of collapsed hill wall,this study takes soil of a typical collapsed Hill wall?red layer,sand layer,clastic layer?in Longmen Town,Anxi County as the research object,and conducts indoor electric reinforcement test based on chemical electro-osmosis method.By observing the parameters of current,drainage and drainage rate during the test,the shear properties of the reinforced undisturbed soil and the remolded soil are compared,the micro-aggregates and mechanical composition of the reinforced soil are analyzed,and the influence of chemical electro-osmosis method on the mechanical properties of the collapsed soil is explored.The results showed that:?1?In the initial stage of electro-osmosis test,CaCl₂ solution injection can significantly improve soil conductivity and electro-osmosis efficiency.Compared with the conventional electro-osmosis method,the drainage rate per unit time of electrochemical method is faster,shortened the electro-osmosis time,but it also affects the degree of cementation of soil,the uneven distribution of water content and shear strength is obvious.According to the analysis of accumulated drainage,it is concluded that the drainage cannot be used as one of the indicators to measure the reinforcement effect for the collapsed hill soil.?2?Under the electrochemical reinforcement,the shear strength of red soil layer is significantly correlated with the concentration of CaCl₂ solution.When the concentration is 35%,the reinforcement effect is the best.The experimental group injected CaCl₂ concentration of sand and clastic layers,the shear strength has been significantly improved in the anode region,the influence of CaCl₂ concentration on the middle and cathode regions is not obvious.Compared with the reinforced undisturbed soil,the cohesion of the three layers of remolded soil decreases as a whole,and the internal friction angle increases.The shear strength of the three layers is the largest when the concentration of CaCl₂ is 0%.?3?By analyzing the composition characteristics of soil micro-aggregates after reinforcement,it can be seen that,the content of micro-aggregates with grain size of 0.25-2 mm in the three soil layers was higher than that in the undisturbed soil layers.With the increase of CaCl₂ concentration,the red layer shows obvious difference from the original soil.It shows that the chemical electro-osmosis method can improve the stability of soil micro-aggregates in collapsed hills and reinforce the soil.From the analysis of soil texture,with the increase of CaCl₂ concentration,the clay particle content in the three soil layers in the anode area decreased gradually,while the clay particle content in the cathode area increased.This indicates that in the electrochemical process,calcium hydrate ions adsorb clay particles and move from the anode to the cathode under the action of electric field and concentrate in the cathode area.