Influence of Water-soil Chemical Interaction on Shear Characteristics of Benggang
[Objective]The study aimed to explore the effects of water-soil chemical interaction on the shear characteristics of Benggang,and to provide a theoretical basis to understand the causes and mechanism of Benggang.[Method]The soil samples from 3 soil layers in a soil profile(red soil layer,sandy soil layer and detritus layer)of a typical Benggang located in Changting County,Fujian Province,were collected and then exchanged with two kinds of electrolyte solutions(Na+and K+)at four different concentrations(0.005,0.01 and 0.1 mol L-1)to analyze their shear characteristics(deviatoric stress,cohesion and internal friction angle).[Result]① The red soil layer had the highest in deviatoric stress,cohesion and internal friction angle,followed by the sandy soil layer and the detritus layer.② The cohesion of the three soil layers exchanged with K+significantly increased as the electrolyte concentration increased,while exchanged with Na+showed the opposite trend.The cohesion of the red soil layer exchanged with K+(0.10 mol L-1)was 17.39％higher than that of the pure water treatment,whereas the internal friction angle of the soil did not differ significantly as the electrolyte concentration increased.③ The deviatoric stress and cohesion of the three soil layers exchanged with K+were significantly greater than those exchanged with Na+,and the cohesion rates of the red soil layer,sandy soil layer and detritus layer exchanged with K+were 9.99％,3.37％and 9.65％higher than that exchanged with Na+,respectively.However,the internal friction angle of the soil did not differ significantly.The effect of the water-soil chemical interaction on cohesion was significantly greater than that of the internal friction angle.[Conclusion]The influence of the concentration of Na+and K+on cohesion is significantly greater than that of internal friction angle.K+can increase the soil shear strength by increasing the soil cohesion and then improve the erosion resistance of the collapsed soil,and the soil shear strength increase with the K+electrolyte solutions.
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